diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index e04daa73..8bd5d3ba 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -1,1543 +1,1543 @@
-/**
- * @file
- * Transmission Control Protocol, outgoing traffic
- *
- * The output functions of TCP.
- *
- */
-
-/*
- * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- *
- * Author: Adam Dunkels <adam@sics.se>
- *
- */
-
-#include "lwip/opt.h"
-
-#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
-
-#include "lwip/tcp_impl.h"
-#include "lwip/def.h"
-#include "lwip/mem.h"
-#include "lwip/memp.h"
-#include "lwip/ip_addr.h"
-#include "lwip/netif.h"
-#include "lwip/inet_chksum.h"
-#include "lwip/stats.h"
-#include "lwip/snmp.h"
-#include "lwip/ip6.h"
-#include "lwip/ip6_addr.h"
-#include "lwip/inet_chksum.h"
-#if LWIP_TCP_TIMESTAMPS
-#include "lwip/sys.h"
-#endif
-
-#include <string.h>
-
-/* Define some copy-macros for checksum-on-copy so that the code looks
-   nicer by preventing too many ifdef's. */
-#if TCP_CHECKSUM_ON_COPY
-#define TCP_DATA_COPY(dst, src, len, seg) do { \
-  tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
-                     len, &seg->chksum, &seg->chksum_swapped); \
-  seg->flags |= TF_SEG_DATA_CHECKSUMMED; } while(0)
-#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped)  \
-  tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
-#else /* TCP_CHECKSUM_ON_COPY*/
-#define TCP_DATA_COPY(dst, src, len, seg)                     MEMCPY(dst, src, len)
-#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
-#endif /* TCP_CHECKSUM_ON_COPY*/
-
-/** Define this to 1 for an extra check that the output checksum is valid
- * (usefule when the checksum is generated by the application, not the stack) */
-#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
-#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK   0
-#endif
-
-/* Forward declarations.*/
-static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb);
-
-/** Allocate a pbuf and create a tcphdr at p->payload, used for output
- * functions other than the default tcp_output -> tcp_output_segment
- * (e.g. tcp_send_empty_ack, etc.)
- *
- * @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
- * @param optlen length of header-options
- * @param datalen length of tcp data to reserve in pbuf
- * @param seqno_be seqno in network byte order (big-endian)
- * @return pbuf with p->payload being the tcp_hdr
- */
-static struct pbuf *
-tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
-                      u32_t seqno_be /* already in network byte order */)
-{
-  struct tcp_hdr *tcphdr;
-  struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
-  if (p != NULL) {
-    LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
-                 (p->len >= TCP_HLEN + optlen));
-    tcphdr = (struct tcp_hdr *)p->payload;
-    tcphdr->src = htons(pcb->local_port);
-    tcphdr->dest = htons(pcb->remote_port);
-    tcphdr->seqno = seqno_be;
-    tcphdr->ackno = htonl(pcb->rcv_nxt);
-    TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
-    tcphdr->wnd = htons(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd));
-    tcphdr->chksum = 0;
-    tcphdr->urgp = 0;
-
-    /* If we're sending a packet, update the announced right window edge */
-    pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
-  }
-  return p;
-}
-
-/**
- * Called by tcp_close() to send a segment including FIN flag but not data.
- *
- * @param pcb the tcp_pcb over which to send a segment
- * @return ERR_OK if sent, another err_t otherwise
- */
-err_t
-tcp_send_fin(struct tcp_pcb *pcb)
-{
-  /* first, try to add the fin to the last unsent segment */
-  if (pcb->unsent != NULL) {
-    struct tcp_seg *last_unsent;
-    for (last_unsent = pcb->unsent; last_unsent->next != NULL;
-         last_unsent = last_unsent->next);
-
-    if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
-      /* no SYN/FIN/RST flag in the header, we can add the FIN flag */
-      TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
-      pcb->flags |= TF_FIN;
-      return ERR_OK;
-    }
-  }
-  /* no data, no length, flags, copy=1, no optdata */
-  return tcp_enqueue_flags(pcb, TCP_FIN);
-}
-
-/**
- * Create a TCP segment with prefilled header.
- *
- * Called by tcp_write and tcp_enqueue_flags.
- *
- * @param pcb Protocol control block for the TCP connection.
- * @param p pbuf that is used to hold the TCP header.
- * @param flags TCP flags for header.
- * @param seqno TCP sequence number of this packet
- * @param optflags options to include in TCP header
- * @return a new tcp_seg pointing to p, or NULL.
- * The TCP header is filled in except ackno and wnd.
- * p is freed on failure.
- */
-static struct tcp_seg *
-tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno, u8_t optflags)
-{
-  struct tcp_seg *seg;
-  u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
-
-  if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n"));
-    pbuf_free(p);
-    return NULL;
-  }
-  seg->flags = optflags;
-  seg->next = NULL;
-  seg->p = p;
-  seg->len = p->tot_len - optlen;
-#if TCP_OVERSIZE_DBGCHECK
-  seg->oversize_left = 0;
-#endif /* TCP_OVERSIZE_DBGCHECK */
-#if TCP_CHECKSUM_ON_COPY
-  seg->chksum = 0;
-  seg->chksum_swapped = 0;
-  /* check optflags */
-  LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
-              (optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
-#endif /* TCP_CHECKSUM_ON_COPY */
-
-  /* build TCP header */
-  if (pbuf_header(p, TCP_HLEN)) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
-    TCP_STATS_INC(tcp.err);
-    tcp_seg_free(seg);
-    return NULL;
-  }
-  seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
-  seg->tcphdr->src = htons(pcb->local_port);
-  seg->tcphdr->dest = htons(pcb->remote_port);
-  seg->tcphdr->seqno = htonl(seqno);
-  /* ackno is set in tcp_output */
-  TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
-  /* wnd and chksum are set in tcp_output */
-  seg->tcphdr->urgp = 0;
-  return seg;
-} 
-
-/**
- * Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
- *
- * This function is like pbuf_alloc(layer, length, PBUF_RAM) except
- * there may be extra bytes available at the end.
- *
- * @param layer flag to define header size.
- * @param length size of the pbuf's payload.
- * @param max_length maximum usable size of payload+oversize.
- * @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
- * @param pcb The TCP connection that willo enqueue the pbuf.
- * @param apiflags API flags given to tcp_write.
- * @param first_seg true when this pbuf will be used in the first enqueued segment.
- * @param 
- */
-#if TCP_OVERSIZE
-static struct pbuf *
-tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
-                  u16_t *oversize, struct tcp_pcb *pcb, u8_t apiflags,
-                  u8_t first_seg)
-{
-  struct pbuf *p;
-  u16_t alloc = length;
-
-#if LWIP_NETIF_TX_SINGLE_PBUF
-  LWIP_UNUSED_ARG(max_length);
-  LWIP_UNUSED_ARG(pcb);
-  LWIP_UNUSED_ARG(apiflags);
-  LWIP_UNUSED_ARG(first_seg);
-  /* always create MSS-sized pbufs */
-  alloc = max_length;
-#else /* LWIP_NETIF_TX_SINGLE_PBUF */
-  if (length < max_length) {
-    /* Should we allocate an oversized pbuf, or just the minimum
-     * length required? If tcp_write is going to be called again
-     * before this segment is transmitted, we want the oversized
-     * buffer. If the segment will be transmitted immediately, we can
-     * save memory by allocating only length. We use a simple
-     * heuristic based on the following information:
-     *
-     * Did the user set TCP_WRITE_FLAG_MORE?
-     *
-     * Will the Nagle algorithm defer transmission of this segment?
-     */
-    if ((apiflags & TCP_WRITE_FLAG_MORE) ||
-        (!(pcb->flags & TF_NODELAY) &&
-         (!first_seg ||
-          pcb->unsent != NULL ||
-          pcb->unacked != NULL))) {
-      alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
-    }
-  }
-#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
-  p = pbuf_alloc(layer, alloc, PBUF_RAM);
-  if (p == NULL) {
-    return NULL;
-  }
-  LWIP_ASSERT("need unchained pbuf", p->next == NULL);
-  *oversize = p->len - length;
-  /* trim p->len to the currently used size */
-  p->len = p->tot_len = length;
-  return p;
-}
-#else /* TCP_OVERSIZE */
-#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
-#endif /* TCP_OVERSIZE */
-
-#if TCP_CHECKSUM_ON_COPY
-/** Add a checksum of newly added data to the segment */
-static void
-tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
-                   u8_t *seg_chksum_swapped)
-{
-  u32_t helper;
-  /* add chksum to old chksum and fold to u16_t */
-  helper = chksum + *seg_chksum;
-  chksum = FOLD_U32T(helper);
-  if ((len & 1) != 0) {
-    *seg_chksum_swapped = 1 - *seg_chksum_swapped;
-    chksum = SWAP_BYTES_IN_WORD(chksum);
-  }
-  *seg_chksum = chksum;
-}
-#endif /* TCP_CHECKSUM_ON_COPY */
-
-/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
- *
- * @param pcb the tcp pcb to check for
- * @param len length of data to send (checked agains snd_buf)
- * @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
- */
-static err_t
-tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
-{
-  /* connection is in invalid state for data transmission? */
-  if ((pcb->state != ESTABLISHED) &&
-      (pcb->state != CLOSE_WAIT) &&
-      (pcb->state != SYN_SENT) &&
-      (pcb->state != SYN_RCVD)) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
-    return ERR_CONN;
-  } else if (len == 0) {
-    return ERR_OK;
-  }
-
-  /* fail on too much data */
-  if (len > pcb->snd_buf) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
-      len, pcb->snd_buf));
-    pcb->flags |= TF_NAGLEMEMERR;
-    return ERR_MEM;
-  }
-
-  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"TCPWNDSIZE_F"\n", (tcpwnd_size_t)pcb->snd_queuelen));
-
-  /* If total number of pbufs on the unsent/unacked queues exceeds the
-   * configured maximum, return an error */
-  /* check for configured max queuelen and possible overflow */
-  if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too long queue %"TCPWNDSIZE_F" (max %"TCPWNDSIZE_F")\n",
-      pcb->snd_queuelen, TCP_SND_QUEUELEN));
-    TCP_STATS_INC(tcp.memerr);
-    pcb->flags |= TF_NAGLEMEMERR;
-    return ERR_MEM;
-  }
-  if (pcb->snd_queuelen != 0) {
-    LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
-      pcb->unacked != NULL || pcb->unsent != NULL);
-  } else {
-    LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
-      pcb->unacked == NULL && pcb->unsent == NULL);
-  }
-  return ERR_OK;
-}
-
-/**
- * Write data for sending (but does not send it immediately).
- *
- * It waits in the expectation of more data being sent soon (as
- * it can send them more efficiently by combining them together).
- * To prompt the system to send data now, call tcp_output() after
- * calling tcp_write().
- *
- * @param pcb Protocol control block for the TCP connection to enqueue data for.
- * @param arg Pointer to the data to be enqueued for sending.
- * @param len Data length in bytes
- * @param apiflags combination of following flags :
- * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
- * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
- * @return ERR_OK if enqueued, another err_t on error
- */
-err_t
-tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
-{
-  struct pbuf *concat_p = NULL;
-  struct tcp_seg *last_unsent = NULL, *seg = NULL, *prev_seg = NULL, *queue = NULL;
-  u16_t pos = 0; /* position in 'arg' data */
-  u16_t queuelen;
-  u8_t optlen = 0;
-  u8_t optflags = 0;
-#if TCP_OVERSIZE
-  u16_t oversize = 0;
-  u16_t oversize_used = 0;
-#endif /* TCP_OVERSIZE */
-#if TCP_CHECKSUM_ON_COPY
-  u16_t concat_chksum = 0;
-  u8_t concat_chksum_swapped = 0;
-  u16_t concat_chksummed = 0;
-#endif /* TCP_CHECKSUM_ON_COPY */
-  err_t err;
-  /* don't allocate segments bigger than half the maximum window we ever received */
-  u16_t mss_local = LWIP_MIN(pcb->mss, pcb->snd_wnd_max/2);
-
-#if LWIP_NETIF_TX_SINGLE_PBUF
-  /* Always copy to try to create single pbufs for TX */
-  apiflags |= TCP_WRITE_FLAG_COPY;
-#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
-
-  LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
-    (void *)pcb, arg, len, (u16_t)apiflags));
-  LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)", 
-             arg != NULL, return ERR_ARG;);
-
-  err = tcp_write_checks(pcb, len);
-  if (err != ERR_OK) {
-    return err;
-  }
-  queuelen = pcb->snd_queuelen;
-
-#if LWIP_TCP_TIMESTAMPS
-  if ((pcb->flags & TF_TIMESTAMP)) {
-    optflags = TF_SEG_OPTS_TS;
-    optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
-  }
-#endif /* LWIP_TCP_TIMESTAMPS */
-
-
-  /*
-   * TCP segmentation is done in three phases with increasing complexity:
-   *
-   * 1. Copy data directly into an oversized pbuf.
-   * 2. Chain a new pbuf to the end of pcb->unsent.
-   * 3. Create new segments.
-   *
-   * We may run out of memory at any point. In that case we must
-   * return ERR_MEM and not change anything in pcb. Therefore, all
-   * changes are recorded in local variables and committed at the end
-   * of the function. Some pcb fields are maintained in local copies:
-   *
-   * queuelen = pcb->snd_queuelen
-   * oversize = pcb->unsent_oversize
-   *
-   * These variables are set consistently by the phases:
-   *
-   * seg points to the last segment tampered with.
-   *
-   * pos records progress as data is segmented.
-   */
-
-  /* Find the tail of the unsent queue. */
-  if (pcb->unsent != NULL) {
-    u16_t space;
-    u16_t unsent_optlen;
-
-    /* @todo: this could be sped up by keeping last_unsent in the pcb */
-    for (last_unsent = pcb->unsent; last_unsent->next != NULL;
-         last_unsent = last_unsent->next);
-
-    /* Usable space at the end of the last unsent segment */
-    unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
-    space = mss_local - (last_unsent->len + unsent_optlen);
-
-    /*
-     * Phase 1: Copy data directly into an oversized pbuf.
-     *
-     * The number of bytes copied is recorded in the oversize_used
-     * variable. The actual copying is done at the bottom of the
-     * function.
-     */
-#if TCP_OVERSIZE
-#if TCP_OVERSIZE_DBGCHECK
-    /* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
-    LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
-                pcb->unsent_oversize == last_unsent->oversize_left);
-#endif /* TCP_OVERSIZE_DBGCHECK */
-    oversize = pcb->unsent_oversize;
-    if (oversize > 0) {
-      LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
-      seg = last_unsent;
-      oversize_used = oversize < len ? oversize : len;
-      pos += oversize_used;
-      oversize -= oversize_used;
-      space -= oversize_used;
-    }
-    /* now we are either finished or oversize is zero */
-    LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) || (pos == len));
-#endif /* TCP_OVERSIZE */
-
-    /*
-     * Phase 2: Chain a new pbuf to the end of pcb->unsent.
-     *
-     * We don't extend segments containing SYN/FIN flags or options
-     * (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
-     * the end.
-     */
-    if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
-      u16_t seglen = space < len - pos ? space : len - pos;
-      seg = last_unsent;
-
-      /* Create a pbuf with a copy or reference to seglen bytes. We
-       * can use PBUF_RAW here since the data appears in the middle of
-       * a segment. A header will never be prepended. */
-      if (apiflags & TCP_WRITE_FLAG_COPY) {
-        /* Data is copied */
-        if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
-          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
-                      ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
-                       seglen));
-          goto memerr;
-        }
-#if TCP_OVERSIZE_DBGCHECK
-        last_unsent->oversize_left += oversize;
-#endif /* TCP_OVERSIZE_DBGCHECK */
-        TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
-#if TCP_CHECKSUM_ON_COPY
-        concat_chksummed += seglen;
-#endif /* TCP_CHECKSUM_ON_COPY */
-      } else {
-        /* Data is not copied */
-        if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
-          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
-                      ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
-          goto memerr;
-        }
-#if TCP_CHECKSUM_ON_COPY
-        /* calculate the checksum of nocopy-data */
-        tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
-          &concat_chksum, &concat_chksum_swapped);
-        concat_chksummed += seglen;
-#endif /* TCP_CHECKSUM_ON_COPY */
-        /* reference the non-volatile payload data */
-        concat_p->payload = (u8_t*)arg + pos;
-      }
-
-      pos += seglen;
-      queuelen += pbuf_clen(concat_p);
-    }
-  } else {
-#if TCP_OVERSIZE
-    LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
-                pcb->unsent_oversize == 0);
-#endif /* TCP_OVERSIZE */
-  }
-
-  /*
-   * Phase 3: Create new segments.
-   *
-   * The new segments are chained together in the local 'queue'
-   * variable, ready to be appended to pcb->unsent.
-   */
-  while (pos < len) {
-    struct pbuf *p;
-    u16_t left = len - pos;
-    u16_t max_len = mss_local - optlen;
-    u16_t seglen = left > max_len ? max_len : left;
-#if TCP_CHECKSUM_ON_COPY
-    u16_t chksum = 0;
-    u8_t chksum_swapped = 0;
-#endif /* TCP_CHECKSUM_ON_COPY */
-
-    if (apiflags & TCP_WRITE_FLAG_COPY) {
-      /* If copy is set, memory should be allocated and data copied
-       * into pbuf */
-      if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
-        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
-        goto memerr;
-      }
-      LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
-                  (p->len >= seglen));
-      TCP_DATA_COPY2((char *)p->payload + optlen, (u8_t*)arg + pos, seglen, &chksum, &chksum_swapped);
-    } else {
-      /* Copy is not set: First allocate a pbuf for holding the data.
-       * Since the referenced data is available at least until it is
-       * sent out on the link (as it has to be ACKed by the remote
-       * party) we can safely use PBUF_ROM instead of PBUF_REF here.
-       */
-      struct pbuf *p2;
-#if TCP_OVERSIZE
-      LWIP_ASSERT("oversize == 0", oversize == 0);
-#endif /* TCP_OVERSIZE */
-      if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
-        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
-        goto memerr;
-      }
-#if TCP_CHECKSUM_ON_COPY
-      /* calculate the checksum of nocopy-data */
-      chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
-#endif /* TCP_CHECKSUM_ON_COPY */
-      /* reference the non-volatile payload data */
-      p2->payload = (u8_t*)arg + pos;
-
-      /* Second, allocate a pbuf for the headers. */
-      if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
-        /* If allocation fails, we have to deallocate the data pbuf as
-         * well. */
-        pbuf_free(p2);
-        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for header pbuf\n"));
-        goto memerr;
-      }
-      /* Concatenate the headers and data pbufs together. */
-      pbuf_cat(p/*header*/, p2/*data*/);
-    }
-
-    queuelen += pbuf_clen(p);
-
-    /* Now that there are more segments queued, we check again if the
-     * length of the queue exceeds the configured maximum or
-     * overflows. */
-    if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
-      LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: queue too long %"TCPWNDSIZE_F" (%"TCPWNDSIZE_F")\n", queuelen, TCP_SND_QUEUELEN));
-      pbuf_free(p);
-      goto memerr;
-    }
-
-    if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
-      goto memerr;
-    }
-#if TCP_OVERSIZE_DBGCHECK
-    seg->oversize_left = oversize;
-#endif /* TCP_OVERSIZE_DBGCHECK */
-#if TCP_CHECKSUM_ON_COPY
-    seg->chksum = chksum;
-    seg->chksum_swapped = chksum_swapped;
-    seg->flags |= TF_SEG_DATA_CHECKSUMMED;
-#endif /* TCP_CHECKSUM_ON_COPY */
-
-    /* first segment of to-be-queued data? */
-    if (queue == NULL) {
-      queue = seg;
-    } else {
-      /* Attach the segment to the end of the queued segments */
-      LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
-      prev_seg->next = seg;
-    }
-    /* remember last segment of to-be-queued data for next iteration */
-    prev_seg = seg;
-
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
-      ntohl(seg->tcphdr->seqno),
-      ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
-
-    pos += seglen;
-  }
-
-  /*
-   * All three segmentation phases were successful. We can commit the
-   * transaction.
-   */
-
-  /*
-   * Phase 1: If data has been added to the preallocated tail of
-   * last_unsent, we update the length fields of the pbuf chain.
-   */
-#if TCP_OVERSIZE
-  if (oversize_used > 0) {
-    struct pbuf *p;
-    /* Bump tot_len of whole chain, len of tail */
-    for (p = last_unsent->p; p; p = p->next) {
-      p->tot_len += oversize_used;
-      if (p->next == NULL) {
-        TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
-        p->len += oversize_used;
-      }
-    }
-    last_unsent->len += oversize_used;
-#if TCP_OVERSIZE_DBGCHECK
-    LWIP_ASSERT("last_unsent->oversize_left >= oversize_used",
-                last_unsent->oversize_left >= oversize_used);
-    last_unsent->oversize_left -= oversize_used;
-#endif /* TCP_OVERSIZE_DBGCHECK */
-  }
-  pcb->unsent_oversize = oversize;
-#endif /* TCP_OVERSIZE */
-
-  /*
-   * Phase 2: concat_p can be concatenated onto last_unsent->p
-   */
-  if (concat_p != NULL) {
-    LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
-      (last_unsent != NULL));
-    pbuf_cat(last_unsent->p, concat_p);
-    last_unsent->len += concat_p->tot_len;
-#if TCP_CHECKSUM_ON_COPY
-    if (concat_chksummed) {
-      tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
-        &last_unsent->chksum_swapped);
-      last_unsent->flags |= TF_SEG_DATA_CHECKSUMMED;
-    }
-#endif /* TCP_CHECKSUM_ON_COPY */
-  }
-
-  /*
-   * Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
-   * is harmless
-   */
-  if (last_unsent == NULL) {
-    pcb->unsent = queue;
-  } else {
-    last_unsent->next = queue;
-  }
-
-  /*
-   * Finally update the pcb state.
-   */
-  pcb->snd_lbb += len;
-  pcb->snd_buf -= len;
-  pcb->snd_queuelen = queuelen;
-
-  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
-    pcb->snd_queuelen));
-  if (pcb->snd_queuelen != 0) {
-    LWIP_ASSERT("tcp_write: valid queue length",
-                pcb->unacked != NULL || pcb->unsent != NULL);
-  }
-
-  /* Set the PSH flag in the last segment that we enqueued. */
-  if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
-    TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
-  }
-
-  return ERR_OK;
-memerr:
-  pcb->flags |= TF_NAGLEMEMERR;
-  TCP_STATS_INC(tcp.memerr);
-
-  if (concat_p != NULL) {
-    pbuf_free(concat_p);
-  }
-  if (queue != NULL) {
-    tcp_segs_free(queue);
-  }
-  if (pcb->snd_queuelen != 0) {
-    LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL ||
-      pcb->unsent != NULL);
-  }
-  LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
-  return ERR_MEM;
-}
-
-/**
- * Enqueue TCP options for transmission.
- *
- * Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
- *
- * @param pcb Protocol control block for the TCP connection.
- * @param flags TCP header flags to set in the outgoing segment.
- * @param optdata pointer to TCP options, or NULL.
- * @param optlen length of TCP options in bytes.
- */
-err_t
-tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
-{
-  struct pbuf *p;
-  struct tcp_seg *seg;
-  u8_t optflags = 0;
-  u8_t optlen = 0;
-
-  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
-
-  LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
-              (flags & (TCP_SYN | TCP_FIN)) != 0);
-
-  /* check for configured max queuelen and possible overflow */
-  if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
-                                       pcb->snd_queuelen, TCP_SND_QUEUELEN));
-    TCP_STATS_INC(tcp.memerr);
-    pcb->flags |= TF_NAGLEMEMERR;
-    return ERR_MEM;
-  }
-
-  if (flags & TCP_SYN) {
-    optflags = TF_SEG_OPTS_MSS;
-#if LWIP_WND_SCALE
-    if ((pcb->state != SYN_RCVD) || (pcb->flags & TF_WND_SCALE)) {
-      /* In a <SYN,ACK> (sent in state SYN_RCVD), the window scale option may only
-         be sent if we received a window scale option from the remote host. */
-      optflags |= TF_SEG_OPTS_WND_SCALE;
-    }
-#endif /* LWIP_WND_SCALE */
-  }
-#if LWIP_TCP_TIMESTAMPS
-  if ((pcb->flags & TF_TIMESTAMP)) {
-    optflags |= TF_SEG_OPTS_TS;
-  }
-#endif /* LWIP_TCP_TIMESTAMPS */
-  optlen = LWIP_TCP_OPT_LENGTH(optflags);
-
-  /* tcp_enqueue_flags is always called with either SYN or FIN in flags.
-   * We need one available snd_buf byte to do that.
-   * This means we can't send FIN while snd_buf==0. A better fix would be to
-   * not include SYN and FIN sequence numbers in the snd_buf count. */
-  if (pcb->snd_buf == 0) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: no send buffer available\n"));
-    TCP_STATS_INC(tcp.memerr);
-    return ERR_MEM;
-  }
-
-  /* Allocate pbuf with room for TCP header + options */
-  if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
-    pcb->flags |= TF_NAGLEMEMERR;
-    TCP_STATS_INC(tcp.memerr);
-    return ERR_MEM;
-  }
-  LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
-              (p->len >= optlen));
-
-  /* Allocate memory for tcp_seg, and fill in fields. */
-  if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
-    pcb->flags |= TF_NAGLEMEMERR;
-    TCP_STATS_INC(tcp.memerr);
-    return ERR_MEM;
-  }
-  LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)seg->tcphdr % MEM_ALIGNMENT) == 0);
-  LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
-
-  LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE,
-              ("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
-               ntohl(seg->tcphdr->seqno),
-               ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
-               (u16_t)flags));
-
-  /* Now append seg to pcb->unsent queue */
-  if (pcb->unsent == NULL) {
-    pcb->unsent = seg;
-  } else {
-    struct tcp_seg *useg;
-    for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
-    useg->next = seg;
-  }
-#if TCP_OVERSIZE
-  /* The new unsent tail has no space */
-  pcb->unsent_oversize = 0;
-#endif /* TCP_OVERSIZE */
-
-  /* SYN and FIN bump the sequence number */
-  if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
-    pcb->snd_lbb++;
-    /* optlen does not influence snd_buf */
-    pcb->snd_buf--;
-  }
-  if (flags & TCP_FIN) {
-    pcb->flags |= TF_FIN;
-  }
-
-  /* update number of segments on the queues */
-  pcb->snd_queuelen += pbuf_clen(seg->p);
-  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
-  if (pcb->snd_queuelen != 0) {
-    LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
-      pcb->unacked != NULL || pcb->unsent != NULL);
-  }
-
-  return ERR_OK;
-}
-
-#if LWIP_TCP_TIMESTAMPS
-/* Build a timestamp option (12 bytes long) at the specified options pointer)
- *
- * @param pcb tcp_pcb
- * @param opts option pointer where to store the timestamp option
- */
-static void
-tcp_build_timestamp_option(struct tcp_pcb *pcb, u32_t *opts)
-{
-  /* Pad with two NOP options to make everything nicely aligned */
-  opts[0] = PP_HTONL(0x0101080A);
-  opts[1] = htonl(sys_now());
-  opts[2] = htonl(pcb->ts_recent);
-}
-#endif
-
-#if LWIP_WND_SCALE
-/** Build a window scale option (3 bytes long) at the specified options pointer)
- *
- * @param opts option pointer where to store the window scale option
- */
-static void
-tcp_build_wnd_scale_option(u32_t *opts)
-{
-  /* Pad with one NOP option to make everything nicely aligned */
-  opts[0] = PP_HTONL(0x01030300 | TCP_RCV_SCALE);
-}
-#endif
-
-/** Send an ACK without data.
- *
- * @param pcb Protocol control block for the TCP connection to send the ACK
- */
-err_t
-tcp_send_empty_ack(struct tcp_pcb *pcb)
-{
-  struct pbuf *p;
-  u8_t optlen = 0;
-#if LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP
-  struct tcp_hdr *tcphdr;
-#endif /* LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP */
-
-#if LWIP_TCP_TIMESTAMPS
-  if (pcb->flags & TF_TIMESTAMP) {
-    optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
-  }
-#endif
-
-  p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
-  if (p == NULL) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
-    return ERR_BUF;
-  }
-#if LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP
-  tcphdr = (struct tcp_hdr *)p->payload;
-#endif /* LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP */
-  LWIP_DEBUGF(TCP_OUTPUT_DEBUG, 
-              ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
-  /* remove ACK flags from the PCB, as we send an empty ACK now */
-  pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
-
-  /* NB. MSS and window scale options are only sent on SYNs, so ignore them here */
-#if LWIP_TCP_TIMESTAMPS
-  pcb->ts_lastacksent = pcb->rcv_nxt;
-
-  if (pcb->flags & TF_TIMESTAMP) {
-    tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
-  }
-#endif 
-
-#if CHECKSUM_GEN_TCP
-  tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len,
-    &pcb->local_ip, &pcb->remote_ip);
-#endif
-#if LWIP_NETIF_HWADDRHINT
-  ipX_output_hinted(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, pcb->tos,
-      IP_PROTO_TCP, &pcb->addr_hint);
-#else /* LWIP_NETIF_HWADDRHINT*/
-  ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, pcb->tos,
-      IP_PROTO_TCP);
-#endif /* LWIP_NETIF_HWADDRHINT*/
-  pbuf_free(p);
-
-  return ERR_OK;
-}
-
-/**
- * Find out what we can send and send it
- *
- * @param pcb Protocol control block for the TCP connection to send data
- * @return ERR_OK if data has been sent or nothing to send
- *         another err_t on error
- */
-err_t
-tcp_output(struct tcp_pcb *pcb)
-{
-  struct tcp_seg *seg, *useg;
-  u32_t wnd, snd_nxt;
-#if TCP_CWND_DEBUG
-  s16_t i = 0;
-#endif /* TCP_CWND_DEBUG */
-
-  /* pcb->state LISTEN not allowed here */
-  LWIP_ASSERT("don't call tcp_output for listen-pcbs",
-    pcb->state != LISTEN);
-
-  /* First, check if we are invoked by the TCP input processing
-     code. If so, we do not output anything. Instead, we rely on the
-     input processing code to call us when input processing is done
-     with. */
-  if (tcp_input_pcb == pcb) {
-    return ERR_OK;
-  }
-
-  wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
-
-  seg = pcb->unsent;
-
-  /* If the TF_ACK_NOW flag is set and no data will be sent (either
-   * because the ->unsent queue is empty or because the window does
-   * not allow it), construct an empty ACK segment and send it.
-   *
-   * If data is to be sent, we will just piggyback the ACK (see below).
-   */
-  if (pcb->flags & TF_ACK_NOW &&
-     (seg == NULL ||
-      ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
-     return tcp_send_empty_ack(pcb);
-  }
-
-  /* useg should point to last segment on unacked queue */
-  useg = pcb->unacked;
-  if (useg != NULL) {
-    for (; useg->next != NULL; useg = useg->next);
-  }
-
-#if TCP_OUTPUT_DEBUG
-  if (seg == NULL) {
-    LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
-                                   (void*)pcb->unsent));
-  }
-#endif /* TCP_OUTPUT_DEBUG */
-#if TCP_CWND_DEBUG
-  if (seg == NULL) {
-    LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"TCPWNDSIZE_F
-                                 ", cwnd %"TCPWNDSIZE_F", wnd %"U32_F
-                                 ", seg == NULL, ack %"U32_F"\n",
-                                 pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
-  } else {
-    LWIP_DEBUGF(TCP_CWND_DEBUG, 
-                ("tcp_output: snd_wnd %"TCPWNDSIZE_F", cwnd %"TCPWNDSIZE_F", wnd %"U32_F
-                 ", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
-                 pcb->snd_wnd, pcb->cwnd, wnd,
-                 ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
-                 ntohl(seg->tcphdr->seqno), pcb->lastack));
-  }
-#endif /* TCP_CWND_DEBUG */
-  /* data available and window allows it to be sent? */
-  while (seg != NULL &&
-         ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
-    LWIP_ASSERT("RST not expected here!", 
-                (TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
-    /* Stop sending if the nagle algorithm would prevent it
-     * Don't stop:
-     * - if tcp_write had a memory error before (prevent delayed ACK timeout) or
-     * - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
-     *   either seg->next != NULL or pcb->unacked == NULL;
-     *   RST is no sent using tcp_write/tcp_output.
-     */
-    if((tcp_do_output_nagle(pcb) == 0) &&
-      ((pcb->flags & (TF_NAGLEMEMERR | TF_FIN)) == 0)){
-      break;
-    }
-#if TCP_CWND_DEBUG
-    LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"TCPWNDSIZE_F", cwnd %"TCPWNDSIZE_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n",
-                            pcb->snd_wnd, pcb->cwnd, wnd,
-                            ntohl(seg->tcphdr->seqno) + seg->len -
-                            pcb->lastack,
-                            ntohl(seg->tcphdr->seqno), pcb->lastack, i));
-    ++i;
-#endif /* TCP_CWND_DEBUG */
-
-    pcb->unsent = seg->next;
-
-    if (pcb->state != SYN_SENT) {
-      TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
-      pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
-    }
-
-#if TCP_OVERSIZE_DBGCHECK
-    seg->oversize_left = 0;
-#endif /* TCP_OVERSIZE_DBGCHECK */
-    tcp_output_segment(seg, pcb);
-    snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
-    if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
-      pcb->snd_nxt = snd_nxt;
-    }
-    /* put segment on unacknowledged list if length > 0 */
-    if (TCP_TCPLEN(seg) > 0) {
-      seg->next = NULL;
-      /* unacked list is empty? */
-      if (pcb->unacked == NULL) {
-        pcb->unacked = seg;
-        useg = seg;
-      /* unacked list is not empty? */
-      } else {
-        /* In the case of fast retransmit, the packet should not go to the tail
-         * of the unacked queue, but rather somewhere before it. We need to check for
-         * this case. -STJ Jul 27, 2004 */
-        if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
-          /* add segment to before tail of unacked list, keeping the list sorted */
-          struct tcp_seg **cur_seg = &(pcb->unacked);
-          while (*cur_seg &&
-            TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
-              cur_seg = &((*cur_seg)->next );
-          }
-          seg->next = (*cur_seg);
-          (*cur_seg) = seg;
-        } else {
-          /* add segment to tail of unacked list */
-          useg->next = seg;
-          useg = useg->next;
-        }
-      }
-    /* do not queue empty segments on the unacked list */
-    } else {
-      tcp_seg_free(seg);
-    }
-    seg = pcb->unsent;
-  }
-#if TCP_OVERSIZE
-  if (pcb->unsent == NULL) {
-    /* last unsent has been removed, reset unsent_oversize */
-    pcb->unsent_oversize = 0;
-  }
-#endif /* TCP_OVERSIZE */
-
-  pcb->flags &= ~TF_NAGLEMEMERR;
-  return ERR_OK;
-}
-
-/**
- * Called by tcp_output() to actually send a TCP segment over IP.
- *
- * @param seg the tcp_seg to send
- * @param pcb the tcp_pcb for the TCP connection used to send the segment
- */
-static void
-tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
-{
-  u16_t len;
-  u32_t *opts;
-
-  /** @bug Exclude retransmitted segments from this count. */
-  snmp_inc_tcpoutsegs();
-
-  /* The TCP header has already been constructed, but the ackno and
-   wnd fields remain. */
-  seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
-
-  /* advertise our receive window size in this TCP segment */
-#if LWIP_WND_SCALE
-  if (seg->flags & TF_SEG_OPTS_WND_SCALE) {
-    /* The Window field in a SYN segment itself (the only type where we send
-       the window scale option) is never scaled. */
-    seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
-  } else
-#endif /* LWIP_WND_SCALE */
-  {
-    seg->tcphdr->wnd = htons(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd));
-  }
-
-  pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
-
-  /* Add any requested options.  NB MSS option is only set on SYN
-     packets, so ignore it here */
-  opts = (u32_t *)(void *)(seg->tcphdr + 1);
-  if (seg->flags & TF_SEG_OPTS_MSS) {
-    u16_t mss;
-#if TCP_CALCULATE_EFF_SEND_MSS
-    mss = tcp_eff_send_mss(TCP_MSS, &pcb->local_ip, &pcb->remote_ip, PCB_ISIPV6(pcb));
-#else /* TCP_CALCULATE_EFF_SEND_MSS */
-    mss = TCP_MSS;
-#endif /* TCP_CALCULATE_EFF_SEND_MSS */
-    *opts = TCP_BUILD_MSS_OPTION(mss);
-    opts += 1;
-  }
-#if LWIP_TCP_TIMESTAMPS
-  pcb->ts_lastacksent = pcb->rcv_nxt;
-
-  if (seg->flags & TF_SEG_OPTS_TS) {
-    tcp_build_timestamp_option(pcb, opts);
-    opts += 3;
-  }
-#endif
-#if LWIP_WND_SCALE
-  if (seg->flags & TF_SEG_OPTS_WND_SCALE) {
-    tcp_build_wnd_scale_option(opts);
-    opts += 1;
-  }
-#endif
-  
-  /* Set retransmission timer running if it is not currently enabled 
-     This must be set before checking the route. */
-  if (pcb->rtime == -1) {
-    pcb->rtime = 0;
-  }
-
-  /* If we don't have a local IP address, we get one by
-     calling ip_route(). */
-  if (ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) {
-    struct netif *netif;
-    ipX_addr_t *local_ip;
-    ipX_route_get_local_ipX(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip, netif, local_ip);
-    if ((netif == NULL) || (local_ip == NULL)) {
-      return;
-    }
-    ipX_addr_copy(PCB_ISIPV6(pcb), pcb->local_ip, *local_ip);
-  }
-
-  if (pcb->rttest == 0) {
-    pcb->rttest = tcp_ticks;
-    pcb->rtseq = ntohl(seg->tcphdr->seqno);
-
-    LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
-  }
-  LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
-          htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
-          seg->len));
-
-  len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload);
-
-  seg->p->len -= len;
-  seg->p->tot_len -= len;
-
-  seg->p->payload = seg->tcphdr;
-
-  seg->tcphdr->chksum = 0;
-#if TCP_CHECKSUM_ON_COPY
-  {
-    u32_t acc;
-#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
-    u16_t chksum_slow = ipX_chksum_pseudo(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP,
-      seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip);
-#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
-    if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
-      LWIP_ASSERT("data included but not checksummed",
-        seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
-    }
-
-    /* rebuild TCP header checksum (TCP header changes for retransmissions!) */
-    acc = ipX_chksum_pseudo_partial(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP,
-      seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4, &pcb->local_ip, &pcb->remote_ip);
-    /* add payload checksum */
-    if (seg->chksum_swapped) {
-      seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
-      seg->chksum_swapped = 0;
-    }
-    acc += (u16_t)~(seg->chksum);
-    seg->tcphdr->chksum = FOLD_U32T(acc);
-#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
-    if (chksum_slow != seg->tcphdr->chksum) {
-      LWIP_DEBUGF(TCP_DEBUG | LWIP_DBG_LEVEL_WARNING,
-                  ("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
-                  seg->tcphdr->chksum, chksum_slow));
-      seg->tcphdr->chksum = chksum_slow;
-    }
-#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
-  }
-#else /* TCP_CHECKSUM_ON_COPY */
-#if CHECKSUM_GEN_TCP
-  seg->tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP,
-    seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip);
-#endif /* CHECKSUM_GEN_TCP */
-#endif /* TCP_CHECKSUM_ON_COPY */
-  TCP_STATS_INC(tcp.xmit);
-
-#if LWIP_NETIF_HWADDRHINT
-  ipX_output_hinted(PCB_ISIPV6(pcb), seg->p, &pcb->local_ip, &pcb->remote_ip,
-    pcb->ttl, pcb->tos, IP_PROTO_TCP, &pcb->addr_hint);
-#else /* LWIP_NETIF_HWADDRHINT*/
-  ipX_output(PCB_ISIPV6(pcb), seg->p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
-    pcb->tos, IP_PROTO_TCP);
-#endif /* LWIP_NETIF_HWADDRHINT*/
-}
-
-/**
- * Send a TCP RESET packet (empty segment with RST flag set) either to
- * abort a connection or to show that there is no matching local connection
- * for a received segment.
- *
- * Called by tcp_abort() (to abort a local connection), tcp_input() (if no
- * matching local pcb was found), tcp_listen_input() (if incoming segment
- * has ACK flag set) and tcp_process() (received segment in the wrong state)
- *
- * Since a RST segment is in most cases not sent for an active connection,
- * tcp_rst() has a number of arguments that are taken from a tcp_pcb for
- * most other segment output functions.
- *
- * @param seqno the sequence number to use for the outgoing segment
- * @param ackno the acknowledge number to use for the outgoing segment
- * @param local_ip the local IP address to send the segment from
- * @param remote_ip the remote IP address to send the segment to
- * @param local_port the local TCP port to send the segment from
- * @param remote_port the remote TCP port to send the segment to
- */
-void
-tcp_rst_impl(u32_t seqno, u32_t ackno,
-  ipX_addr_t *local_ip, ipX_addr_t *remote_ip,
-  u16_t local_port, u16_t remote_port
-#if LWIP_IPV6
-  , u8_t isipv6
-#endif /* LWIP_IPV6 */
-  )
-{
-  struct pbuf *p;
-  struct tcp_hdr *tcphdr;
-  p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
-  if (p == NULL) {
-      LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
-      return;
-  }
-  LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
-              (p->len >= sizeof(struct tcp_hdr)));
-
-  tcphdr = (struct tcp_hdr *)p->payload;
-  tcphdr->src = htons(local_port);
-  tcphdr->dest = htons(remote_port);
-  tcphdr->seqno = htonl(seqno);
-  tcphdr->ackno = htonl(ackno);
-  TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST | TCP_ACK);
-#if LWIP_WND_SCALE
-  tcphdr->wnd = PP_HTONS(((TCP_WND >> TCP_RCV_SCALE) & 0xFFFF));
-#else
-  tcphdr->wnd = PP_HTONS(TCP_WND);
-#endif
-  tcphdr->chksum = 0;
-  tcphdr->urgp = 0;
-
-  TCP_STATS_INC(tcp.xmit);
-  snmp_inc_tcpoutrsts();
-
-#if CHECKSUM_GEN_TCP
-  tcphdr->chksum = ipX_chksum_pseudo(isipv6, p, IP_PROTO_TCP, p->tot_len,
-                                     local_ip, remote_ip);
-#endif
-  /* Send output with hardcoded TTL/HL since we have no access to the pcb */
-  ipX_output(isipv6, p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
-  pbuf_free(p);
-  LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
-}
-
-/**
- * Requeue all unacked segments for retransmission
- *
- * Called by tcp_slowtmr() for slow retransmission.
- *
- * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
- */
-void
-tcp_rexmit_rto(struct tcp_pcb *pcb)
-{
-  struct tcp_seg *seg;
-
-  if (pcb->unacked == NULL) {
-    return;
-  }
-
-  /* Move all unacked segments to the head of the unsent queue */
-  for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
-  /* concatenate unsent queue after unacked queue */
-  seg->next = pcb->unsent;
-#if TCP_OVERSIZE && TCP_OVERSIZE_DBGCHECK
-  /* if last unsent changed, we need to update unsent_oversize */
-  if (pcb->unsent == NULL) {
-    pcb->unsent_oversize = seg->oversize_left;
-  }
-#endif /* TCP_OVERSIZE && TCP_OVERSIZE_DBGCHECK*/
-  /* unsent queue is the concatenated queue (of unacked, unsent) */
-  pcb->unsent = pcb->unacked;
-  /* unacked queue is now empty */
-  pcb->unacked = NULL;
-
-  /* increment number of retransmissions */
-  ++pcb->nrtx;
-
-  /* Don't take any RTT measurements after retransmitting. */
-  pcb->rttest = 0;
-
-  /* Do the actual retransmission */
-  tcp_output(pcb);
-}
-
-/**
- * Requeue the first unacked segment for retransmission
- *
- * Called by tcp_receive() for fast retramsmit.
- *
- * @param pcb the tcp_pcb for which to retransmit the first unacked segment
- */
-void
-tcp_rexmit(struct tcp_pcb *pcb)
-{
-  struct tcp_seg *seg;
-  struct tcp_seg **cur_seg;
-
-  if (pcb->unacked == NULL) {
-    return;
-  }
-
-  /* Move the first unacked segment to the unsent queue */
-  /* Keep the unsent queue sorted. */
-  seg = pcb->unacked;
-  pcb->unacked = seg->next;
-
-  cur_seg = &(pcb->unsent);
-  while (*cur_seg &&
-    TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
-      cur_seg = &((*cur_seg)->next );
-  }
-  seg->next = *cur_seg;
-  *cur_seg = seg;
-#if TCP_OVERSIZE
-  if (seg->next == NULL) {
-    /* the retransmitted segment is last in unsent, so reset unsent_oversize */
-    pcb->unsent_oversize = 0;
-  }
-#endif /* TCP_OVERSIZE */
-
-  ++pcb->nrtx;
-
-  /* Don't take any rtt measurements after retransmitting. */
-  pcb->rttest = 0;
-
-  /* Do the actual retransmission. */
-  snmp_inc_tcpretranssegs();
-  /* No need to call tcp_output: we are always called from tcp_input()
-     and thus tcp_output directly returns. */
-}
-
-
-/**
- * Handle retransmission after three dupacks received
- *
- * @param pcb the tcp_pcb for which to retransmit the first unacked segment
- */
-void 
-tcp_rexmit_fast(struct tcp_pcb *pcb)
-{
-  if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
-    /* This is fast retransmit. Retransmit the first unacked segment. */
-    LWIP_DEBUGF(TCP_FR_DEBUG, 
-                ("tcp_receive: dupacks %"U16_F" (%"U32_F
-                 "), fast retransmit %"U32_F"\n",
-                 (u16_t)pcb->dupacks, pcb->lastack,
-                 ntohl(pcb->unacked->tcphdr->seqno)));
-    tcp_rexmit(pcb);
-
-    /* Set ssthresh to half of the minimum of the current
-     * cwnd and the advertised window */
-    if (pcb->cwnd > pcb->snd_wnd) {
-      pcb->ssthresh = pcb->snd_wnd / 2;
-    } else {
-      pcb->ssthresh = pcb->cwnd / 2;
-    }
-    
-    /* The minimum value for ssthresh should be 2 MSS */
-    if (pcb->ssthresh < (2U * pcb->mss)) {
-      LWIP_DEBUGF(TCP_FR_DEBUG, 
-                  ("tcp_receive: The minimum value for ssthresh %"U16_F
-                   " should be min 2 mss %"U16_F"...\n",
-                   pcb->ssthresh, 2*pcb->mss));
-      pcb->ssthresh = 2*pcb->mss;
-    }
-    
-    pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
-    pcb->flags |= TF_INFR;
-  } 
-}
-
-
-/**
- * Send keepalive packets to keep a connection active although
- * no data is sent over it.
- *
- * Called by tcp_slowtmr()
- *
- * @param pcb the tcp_pcb for which to send a keepalive packet
- */
-void
-tcp_keepalive(struct tcp_pcb *pcb)
-{
-  struct pbuf *p;
-#if CHECKSUM_GEN_TCP
-  struct tcp_hdr *tcphdr;
-#endif /* CHECKSUM_GEN_TCP */
-
-  LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to "));
-  ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip);
-  LWIP_DEBUGF(TCP_DEBUG, ("\n"));
-
-  LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F"   pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n", 
-                          tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
-   
-  p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
-  if(p == NULL) {
-    LWIP_DEBUGF(TCP_DEBUG, 
-                ("tcp_keepalive: could not allocate memory for pbuf\n"));
-    return;
-  }
-#if CHECKSUM_GEN_TCP
-  tcphdr = (struct tcp_hdr *)p->payload;
-
-  tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len,
-      &pcb->local_ip, &pcb->remote_ip);
-#endif /* CHECKSUM_GEN_TCP */
-  TCP_STATS_INC(tcp.xmit);
-
-  /* Send output to IP */
-#if LWIP_NETIF_HWADDRHINT
-  ipX_output_hinted(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip,
-    pcb->ttl, 0, IP_PROTO_TCP, &pcb->addr_hint);
-#else /* LWIP_NETIF_HWADDRHINT*/
-  ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
-    0, IP_PROTO_TCP);
-#endif /* LWIP_NETIF_HWADDRHINT*/
-
-  pbuf_free(p);
-
-  LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
-                          pcb->snd_nxt - 1, pcb->rcv_nxt));
-}
-
-
-/**
- * Send persist timer zero-window probes to keep a connection active
- * when a window update is lost.
- *
- * Called by tcp_slowtmr()
- *
- * @param pcb the tcp_pcb for which to send a zero-window probe packet
- */
-void
-tcp_zero_window_probe(struct tcp_pcb *pcb)
-{
-  struct pbuf *p;
-  struct tcp_hdr *tcphdr;
-  struct tcp_seg *seg;
-  u16_t len;
-  u8_t is_fin;
-
-  LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: sending ZERO WINDOW probe to "));
-  ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip);
-  LWIP_DEBUGF(TCP_DEBUG, ("\n"));
-
-  LWIP_DEBUGF(TCP_DEBUG, 
-              ("tcp_zero_window_probe: tcp_ticks %"U32_F
-               "   pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n", 
-               tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
-
-  seg = pcb->unacked;
-
-  if(seg == NULL) {
-    seg = pcb->unsent;
-  }
-  if(seg == NULL) {
-    return;
-  }
-
-  is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
-  /* we want to send one seqno: either FIN or data (no options) */
-  len = is_fin ? 0 : 1;
-
-  p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
-  if(p == NULL) {
-    LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
-    return;
-  }
-  tcphdr = (struct tcp_hdr *)p->payload;
-
-  if (is_fin) {
-    /* FIN segment, no data */
-    TCPH_FLAGS_SET(tcphdr, TCP_ACK | TCP_FIN);
-  } else {
-    /* Data segment, copy in one byte from the head of the unacked queue */
-    char *d = ((char *)p->payload + TCP_HLEN);
-    /* Depending on whether the segment has already been sent (unacked) or not
-       (unsent), seg->p->payload points to the IP header or TCP header.
-       Ensure we copy the first TCP data byte: */
-    pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len);
-  }
-
-#if CHECKSUM_GEN_TCP
-  tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len,
-      &pcb->local_ip, &pcb->remote_ip);
-#endif
-  TCP_STATS_INC(tcp.xmit);
-
-  /* Send output to IP */
-#if LWIP_NETIF_HWADDRHINT
-  ipX_output_hinted(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
-    0, IP_PROTO_TCP, &pcb->addr_hint);
-#else /* LWIP_NETIF_HWADDRHINT*/
-  ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
-#endif /* LWIP_NETIF_HWADDRHINT*/
-
-  pbuf_free(p);
-
-  LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
-                          " ackno %"U32_F".\n",
-                          pcb->snd_nxt - 1, pcb->rcv_nxt));
-}
-#endif /* LWIP_TCP */
+/**
+ * @file
+ * Transmission Control Protocol, outgoing traffic
+ *
+ * The output functions of TCP.
+ *
+ */
+
+/*
+ * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ *
+ * Author: Adam Dunkels <adam@sics.se>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
+
+#include "lwip/tcp_impl.h"
+#include "lwip/def.h"
+#include "lwip/mem.h"
+#include "lwip/memp.h"
+#include "lwip/ip_addr.h"
+#include "lwip/netif.h"
+#include "lwip/inet_chksum.h"
+#include "lwip/stats.h"
+#include "lwip/snmp.h"
+#include "lwip/ip6.h"
+#include "lwip/ip6_addr.h"
+#include "lwip/inet_chksum.h"
+#if LWIP_TCP_TIMESTAMPS
+#include "lwip/sys.h"
+#endif
+
+#include <string.h>
+
+/* Define some copy-macros for checksum-on-copy so that the code looks
+   nicer by preventing too many ifdef's. */
+#if TCP_CHECKSUM_ON_COPY
+#define TCP_DATA_COPY(dst, src, len, seg) do { \
+  tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), \
+                     len, &seg->chksum, &seg->chksum_swapped); \
+  seg->flags |= TF_SEG_DATA_CHECKSUMMED; } while(0)
+#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped)  \
+  tcp_seg_add_chksum(LWIP_CHKSUM_COPY(dst, src, len), len, chksum, chksum_swapped);
+#else /* TCP_CHECKSUM_ON_COPY*/
+#define TCP_DATA_COPY(dst, src, len, seg)                     MEMCPY(dst, src, len)
+#define TCP_DATA_COPY2(dst, src, len, chksum, chksum_swapped) MEMCPY(dst, src, len)
+#endif /* TCP_CHECKSUM_ON_COPY*/
+
+/** Define this to 1 for an extra check that the output checksum is valid
+ * (usefule when the checksum is generated by the application, not the stack) */
+#ifndef TCP_CHECKSUM_ON_COPY_SANITY_CHECK
+#define TCP_CHECKSUM_ON_COPY_SANITY_CHECK   0
+#endif
+
+/* Forward declarations.*/
+static void tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb);
+
+/** Allocate a pbuf and create a tcphdr at p->payload, used for output
+ * functions other than the default tcp_output -> tcp_output_segment
+ * (e.g. tcp_send_empty_ack, etc.)
+ *
+ * @param pcb tcp pcb for which to send a packet (used to initialize tcp_hdr)
+ * @param optlen length of header-options
+ * @param datalen length of tcp data to reserve in pbuf
+ * @param seqno_be seqno in network byte order (big-endian)
+ * @return pbuf with p->payload being the tcp_hdr
+ */
+static struct pbuf *
+tcp_output_alloc_header(struct tcp_pcb *pcb, u16_t optlen, u16_t datalen,
+                      u32_t seqno_be /* already in network byte order */)
+{
+  struct tcp_hdr *tcphdr;
+  struct pbuf *p = pbuf_alloc(PBUF_IP, TCP_HLEN + optlen + datalen, PBUF_RAM);
+  if (p != NULL) {
+    LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
+                 (p->len >= TCP_HLEN + optlen));
+    tcphdr = (struct tcp_hdr *)p->payload;
+    tcphdr->src = htons(pcb->local_port);
+    tcphdr->dest = htons(pcb->remote_port);
+    tcphdr->seqno = seqno_be;
+    tcphdr->ackno = htonl(pcb->rcv_nxt);
+    TCPH_HDRLEN_FLAGS_SET(tcphdr, (5 + optlen / 4), TCP_ACK);
+    tcphdr->wnd = htons(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd));
+    tcphdr->chksum = 0;
+    tcphdr->urgp = 0;
+
+    /* If we're sending a packet, update the announced right window edge */
+    pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
+  }
+  return p;
+}
+
+/**
+ * Called by tcp_close() to send a segment including FIN flag but not data.
+ *
+ * @param pcb the tcp_pcb over which to send a segment
+ * @return ERR_OK if sent, another err_t otherwise
+ */
+err_t
+tcp_send_fin(struct tcp_pcb *pcb)
+{
+  /* first, try to add the fin to the last unsent segment */
+  if (pcb->unsent != NULL) {
+    struct tcp_seg *last_unsent;
+    for (last_unsent = pcb->unsent; last_unsent->next != NULL;
+         last_unsent = last_unsent->next);
+
+    if ((TCPH_FLAGS(last_unsent->tcphdr) & (TCP_SYN | TCP_FIN | TCP_RST)) == 0) {
+      /* no SYN/FIN/RST flag in the header, we can add the FIN flag */
+      TCPH_SET_FLAG(last_unsent->tcphdr, TCP_FIN);
+      pcb->flags |= TF_FIN;
+      return ERR_OK;
+    }
+  }
+  /* no data, no length, flags, copy=1, no optdata */
+  return tcp_enqueue_flags(pcb, TCP_FIN);
+}
+
+/**
+ * Create a TCP segment with prefilled header.
+ *
+ * Called by tcp_write and tcp_enqueue_flags.
+ *
+ * @param pcb Protocol control block for the TCP connection.
+ * @param p pbuf that is used to hold the TCP header.
+ * @param flags TCP flags for header.
+ * @param seqno TCP sequence number of this packet
+ * @param optflags options to include in TCP header
+ * @return a new tcp_seg pointing to p, or NULL.
+ * The TCP header is filled in except ackno and wnd.
+ * p is freed on failure.
+ */
+static struct tcp_seg *
+tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno, u8_t optflags)
+{
+  struct tcp_seg *seg;
+  u8_t optlen = LWIP_TCP_OPT_LENGTH(optflags);
+
+  if ((seg = (struct tcp_seg *)memp_malloc(MEMP_TCP_SEG)) == NULL) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no memory.\n"));
+    pbuf_free(p);
+    return NULL;
+  }
+  seg->flags = optflags;
+  seg->next = NULL;
+  seg->p = p;
+  seg->len = p->tot_len - optlen;
+#if TCP_OVERSIZE_DBGCHECK
+  seg->oversize_left = 0;
+#endif /* TCP_OVERSIZE_DBGCHECK */
+#if TCP_CHECKSUM_ON_COPY
+  seg->chksum = 0;
+  seg->chksum_swapped = 0;
+  /* check optflags */
+  LWIP_ASSERT("invalid optflags passed: TF_SEG_DATA_CHECKSUMMED",
+              (optflags & TF_SEG_DATA_CHECKSUMMED) == 0);
+#endif /* TCP_CHECKSUM_ON_COPY */
+
+  /* build TCP header */
+  if (pbuf_header(p, TCP_HLEN)) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_create_segment: no room for TCP header in pbuf.\n"));
+    TCP_STATS_INC(tcp.err);
+    tcp_seg_free(seg);
+    return NULL;
+  }
+  seg->tcphdr = (struct tcp_hdr *)seg->p->payload;
+  seg->tcphdr->src = htons(pcb->local_port);
+  seg->tcphdr->dest = htons(pcb->remote_port);
+  seg->tcphdr->seqno = htonl(seqno);
+  /* ackno is set in tcp_output */
+  TCPH_HDRLEN_FLAGS_SET(seg->tcphdr, (5 + optlen / 4), flags);
+  /* wnd and chksum are set in tcp_output */
+  seg->tcphdr->urgp = 0;
+  return seg;
+} 
+
+/**
+ * Allocate a PBUF_RAM pbuf, perhaps with extra space at the end.
+ *
+ * This function is like pbuf_alloc(layer, length, PBUF_RAM) except
+ * there may be extra bytes available at the end.
+ *
+ * @param layer flag to define header size.
+ * @param length size of the pbuf's payload.
+ * @param max_length maximum usable size of payload+oversize.
+ * @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
+ * @param pcb The TCP connection that willo enqueue the pbuf.
+ * @param apiflags API flags given to tcp_write.
+ * @param first_seg true when this pbuf will be used in the first enqueued segment.
+ * @param 
+ */
+#if TCP_OVERSIZE
+static struct pbuf *
+tcp_pbuf_prealloc(pbuf_layer layer, u16_t length, u16_t max_length,
+                  u16_t *oversize, struct tcp_pcb *pcb, u8_t apiflags,
+                  u8_t first_seg)
+{
+  struct pbuf *p;
+  u16_t alloc = length;
+
+#if LWIP_NETIF_TX_SINGLE_PBUF
+  LWIP_UNUSED_ARG(max_length);
+  LWIP_UNUSED_ARG(pcb);
+  LWIP_UNUSED_ARG(apiflags);
+  LWIP_UNUSED_ARG(first_seg);
+  /* always create MSS-sized pbufs */
+  alloc = max_length;
+#else /* LWIP_NETIF_TX_SINGLE_PBUF */
+  if (length < max_length) {
+    /* Should we allocate an oversized pbuf, or just the minimum
+     * length required? If tcp_write is going to be called again
+     * before this segment is transmitted, we want the oversized
+     * buffer. If the segment will be transmitted immediately, we can
+     * save memory by allocating only length. We use a simple
+     * heuristic based on the following information:
+     *
+     * Did the user set TCP_WRITE_FLAG_MORE?
+     *
+     * Will the Nagle algorithm defer transmission of this segment?
+     */
+    if ((apiflags & TCP_WRITE_FLAG_MORE) ||
+        (!(pcb->flags & TF_NODELAY) &&
+         (!first_seg ||
+          pcb->unsent != NULL ||
+          pcb->unacked != NULL))) {
+      alloc = LWIP_MIN(max_length, LWIP_MEM_ALIGN_SIZE(length + TCP_OVERSIZE));
+    }
+  }
+#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
+  p = pbuf_alloc(layer, alloc, PBUF_RAM);
+  if (p == NULL) {
+    return NULL;
+  }
+  LWIP_ASSERT("need unchained pbuf", p->next == NULL);
+  *oversize = p->len - length;
+  /* trim p->len to the currently used size */
+  p->len = p->tot_len = length;
+  return p;
+}
+#else /* TCP_OVERSIZE */
+#define tcp_pbuf_prealloc(layer, length, mx, os, pcb, api, fst) pbuf_alloc((layer), (length), PBUF_RAM)
+#endif /* TCP_OVERSIZE */
+
+#if TCP_CHECKSUM_ON_COPY
+/** Add a checksum of newly added data to the segment */
+static void
+tcp_seg_add_chksum(u16_t chksum, u16_t len, u16_t *seg_chksum,
+                   u8_t *seg_chksum_swapped)
+{
+  u32_t helper;
+  /* add chksum to old chksum and fold to u16_t */
+  helper = chksum + *seg_chksum;
+  chksum = FOLD_U32T(helper);
+  if ((len & 1) != 0) {
+    *seg_chksum_swapped = 1 - *seg_chksum_swapped;
+    chksum = SWAP_BYTES_IN_WORD(chksum);
+  }
+  *seg_chksum = chksum;
+}
+#endif /* TCP_CHECKSUM_ON_COPY */
+
+/** Checks if tcp_write is allowed or not (checks state, snd_buf and snd_queuelen).
+ *
+ * @param pcb the tcp pcb to check for
+ * @param len length of data to send (checked agains snd_buf)
+ * @return ERR_OK if tcp_write is allowed to proceed, another err_t otherwise
+ */
+static err_t
+tcp_write_checks(struct tcp_pcb *pcb, u16_t len)
+{
+  /* connection is in invalid state for data transmission? */
+  if ((pcb->state != ESTABLISHED) &&
+      (pcb->state != CLOSE_WAIT) &&
+      (pcb->state != SYN_SENT) &&
+      (pcb->state != SYN_RCVD)) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_STATE | LWIP_DBG_LEVEL_SEVERE, ("tcp_write() called in invalid state\n"));
+    return ERR_CONN;
+  } else if (len == 0) {
+    return ERR_OK;
+  }
+
+  /* fail on too much data */
+  if (len > pcb->snd_buf) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too much data (len=%"U16_F" > snd_buf=%"U16_F")\n",
+      len, pcb->snd_buf));
+    pcb->flags |= TF_NAGLEMEMERR;
+    return ERR_MEM;
+  }
+
+  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: queuelen: %"TCPWNDSIZE_F"\n", (tcpwnd_size_t)pcb->snd_queuelen));
+
+  /* If total number of pbufs on the unsent/unacked queues exceeds the
+   * configured maximum, return an error */
+  /* check for configured max queuelen and possible overflow */
+  if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_write: too long queue %"TCPWNDSIZE_F" (max %"TCPWNDSIZE_F")\n",
+      pcb->snd_queuelen, TCP_SND_QUEUELEN));
+    TCP_STATS_INC(tcp.memerr);
+    pcb->flags |= TF_NAGLEMEMERR;
+    return ERR_MEM;
+  }
+  if (pcb->snd_queuelen != 0) {
+    LWIP_ASSERT("tcp_write: pbufs on queue => at least one queue non-empty",
+      pcb->unacked != NULL || pcb->unsent != NULL);
+  } else {
+    LWIP_ASSERT("tcp_write: no pbufs on queue => both queues empty",
+      pcb->unacked == NULL && pcb->unsent == NULL);
+  }
+  return ERR_OK;
+}
+
+/**
+ * Write data for sending (but does not send it immediately).
+ *
+ * It waits in the expectation of more data being sent soon (as
+ * it can send them more efficiently by combining them together).
+ * To prompt the system to send data now, call tcp_output() after
+ * calling tcp_write().
+ *
+ * @param pcb Protocol control block for the TCP connection to enqueue data for.
+ * @param arg Pointer to the data to be enqueued for sending.
+ * @param len Data length in bytes
+ * @param apiflags combination of following flags :
+ * - TCP_WRITE_FLAG_COPY (0x01) data will be copied into memory belonging to the stack
+ * - TCP_WRITE_FLAG_MORE (0x02) for TCP connection, PSH flag will be set on last segment sent,
+ * @return ERR_OK if enqueued, another err_t on error
+ */
+err_t
+tcp_write(struct tcp_pcb *pcb, const void *arg, u16_t len, u8_t apiflags)
+{
+  struct pbuf *concat_p = NULL;
+  struct tcp_seg *last_unsent = NULL, *seg = NULL, *prev_seg = NULL, *queue = NULL;
+  u16_t pos = 0; /* position in 'arg' data */
+  u16_t queuelen;
+  u8_t optlen = 0;
+  u8_t optflags = 0;
+#if TCP_OVERSIZE
+  u16_t oversize = 0;
+  u16_t oversize_used = 0;
+#endif /* TCP_OVERSIZE */
+#if TCP_CHECKSUM_ON_COPY
+  u16_t concat_chksum = 0;
+  u8_t concat_chksum_swapped = 0;
+  u16_t concat_chksummed = 0;
+#endif /* TCP_CHECKSUM_ON_COPY */
+  err_t err;
+  /* don't allocate segments bigger than half the maximum window we ever received */
+  u16_t mss_local = LWIP_MIN(pcb->mss, pcb->snd_wnd_max/2);
+
+#if LWIP_NETIF_TX_SINGLE_PBUF
+  /* Always copy to try to create single pbufs for TX */
+  apiflags |= TCP_WRITE_FLAG_COPY;
+#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
+
+  LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_write(pcb=%p, data=%p, len=%"U16_F", apiflags=%"U16_F")\n",
+    (void *)pcb, arg, len, (u16_t)apiflags));
+  LWIP_ERROR("tcp_write: arg == NULL (programmer violates API)", 
+             arg != NULL, return ERR_ARG;);
+
+  err = tcp_write_checks(pcb, len);
+  if (err != ERR_OK) {
+    return err;
+  }
+  queuelen = pcb->snd_queuelen;
+
+#if LWIP_TCP_TIMESTAMPS
+  if ((pcb->flags & TF_TIMESTAMP)) {
+    optflags = TF_SEG_OPTS_TS;
+    optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
+  }
+#endif /* LWIP_TCP_TIMESTAMPS */
+
+
+  /*
+   * TCP segmentation is done in three phases with increasing complexity:
+   *
+   * 1. Copy data directly into an oversized pbuf.
+   * 2. Chain a new pbuf to the end of pcb->unsent.
+   * 3. Create new segments.
+   *
+   * We may run out of memory at any point. In that case we must
+   * return ERR_MEM and not change anything in pcb. Therefore, all
+   * changes are recorded in local variables and committed at the end
+   * of the function. Some pcb fields are maintained in local copies:
+   *
+   * queuelen = pcb->snd_queuelen
+   * oversize = pcb->unsent_oversize
+   *
+   * These variables are set consistently by the phases:
+   *
+   * seg points to the last segment tampered with.
+   *
+   * pos records progress as data is segmented.
+   */
+
+  /* Find the tail of the unsent queue. */
+  if (pcb->unsent != NULL) {
+    u16_t space;
+    u16_t unsent_optlen;
+
+    /* @todo: this could be sped up by keeping last_unsent in the pcb */
+    for (last_unsent = pcb->unsent; last_unsent->next != NULL;
+         last_unsent = last_unsent->next);
+
+    /* Usable space at the end of the last unsent segment */
+    unsent_optlen = LWIP_TCP_OPT_LENGTH(last_unsent->flags);
+    space = mss_local - (last_unsent->len + unsent_optlen);
+
+    /*
+     * Phase 1: Copy data directly into an oversized pbuf.
+     *
+     * The number of bytes copied is recorded in the oversize_used
+     * variable. The actual copying is done at the bottom of the
+     * function.
+     */
+#if TCP_OVERSIZE
+#if TCP_OVERSIZE_DBGCHECK
+    /* check that pcb->unsent_oversize matches last_unsent->unsent_oversize */
+    LWIP_ASSERT("unsent_oversize mismatch (pcb vs. last_unsent)",
+                pcb->unsent_oversize == last_unsent->oversize_left);
+#endif /* TCP_OVERSIZE_DBGCHECK */
+    oversize = pcb->unsent_oversize;
+    if (oversize > 0) {
+      LWIP_ASSERT("inconsistent oversize vs. space", oversize_used <= space);
+      seg = last_unsent;
+      oversize_used = oversize < len ? oversize : len;
+      pos += oversize_used;
+      oversize -= oversize_used;
+      space -= oversize_used;
+    }
+    /* now we are either finished or oversize is zero */
+    LWIP_ASSERT("inconsistend oversize vs. len", (oversize == 0) || (pos == len));
+#endif /* TCP_OVERSIZE */
+
+    /*
+     * Phase 2: Chain a new pbuf to the end of pcb->unsent.
+     *
+     * We don't extend segments containing SYN/FIN flags or options
+     * (len==0). The new pbuf is kept in concat_p and pbuf_cat'ed at
+     * the end.
+     */
+    if ((pos < len) && (space > 0) && (last_unsent->len > 0)) {
+      u16_t seglen = space < len - pos ? space : len - pos;
+      seg = last_unsent;
+
+      /* Create a pbuf with a copy or reference to seglen bytes. We
+       * can use PBUF_RAW here since the data appears in the middle of
+       * a segment. A header will never be prepended. */
+      if (apiflags & TCP_WRITE_FLAG_COPY) {
+        /* Data is copied */
+        if ((concat_p = tcp_pbuf_prealloc(PBUF_RAW, seglen, space, &oversize, pcb, apiflags, 1)) == NULL) {
+          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
+                      ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n",
+                       seglen));
+          goto memerr;
+        }
+#if TCP_OVERSIZE_DBGCHECK
+        last_unsent->oversize_left += oversize;
+#endif /* TCP_OVERSIZE_DBGCHECK */
+        TCP_DATA_COPY2(concat_p->payload, (u8_t*)arg + pos, seglen, &concat_chksum, &concat_chksum_swapped);
+#if TCP_CHECKSUM_ON_COPY
+        concat_chksummed += seglen;
+#endif /* TCP_CHECKSUM_ON_COPY */
+      } else {
+        /* Data is not copied */
+        if ((concat_p = pbuf_alloc(PBUF_RAW, seglen, PBUF_ROM)) == NULL) {
+          LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2,
+                      ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
+          goto memerr;
+        }
+#if TCP_CHECKSUM_ON_COPY
+        /* calculate the checksum of nocopy-data */
+        tcp_seg_add_chksum(~inet_chksum((u8_t*)arg + pos, seglen), seglen,
+          &concat_chksum, &concat_chksum_swapped);
+        concat_chksummed += seglen;
+#endif /* TCP_CHECKSUM_ON_COPY */
+        /* reference the non-volatile payload data */
+        concat_p->payload = (u8_t*)arg + pos;
+      }
+
+      pos += seglen;
+      queuelen += pbuf_clen(concat_p);
+    }
+  } else {
+#if TCP_OVERSIZE
+    LWIP_ASSERT("unsent_oversize mismatch (pcb->unsent is NULL)",
+                pcb->unsent_oversize == 0);
+#endif /* TCP_OVERSIZE */
+  }
+
+  /*
+   * Phase 3: Create new segments.
+   *
+   * The new segments are chained together in the local 'queue'
+   * variable, ready to be appended to pcb->unsent.
+   */
+  while (pos < len) {
+    struct pbuf *p;
+    u16_t left = len - pos;
+    u16_t max_len = mss_local - optlen;
+    u16_t seglen = left > max_len ? max_len : left;
+#if TCP_CHECKSUM_ON_COPY
+    u16_t chksum = 0;
+    u8_t chksum_swapped = 0;
+#endif /* TCP_CHECKSUM_ON_COPY */
+
+    if (apiflags & TCP_WRITE_FLAG_COPY) {
+      /* If copy is set, memory should be allocated and data copied
+       * into pbuf */
+      if ((p = tcp_pbuf_prealloc(PBUF_TRANSPORT, seglen + optlen, mss_local, &oversize, pcb, apiflags, queue == NULL)) == NULL) {
+        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write : could not allocate memory for pbuf copy size %"U16_F"\n", seglen));
+        goto memerr;
+      }
+      LWIP_ASSERT("tcp_write: check that first pbuf can hold the complete seglen",
+                  (p->len >= seglen));
+      TCP_DATA_COPY2((char *)p->payload + optlen, (u8_t*)arg + pos, seglen, &chksum, &chksum_swapped);
+    } else {
+      /* Copy is not set: First allocate a pbuf for holding the data.
+       * Since the referenced data is available at least until it is
+       * sent out on the link (as it has to be ACKed by the remote
+       * party) we can safely use PBUF_ROM instead of PBUF_REF here.
+       */
+      struct pbuf *p2;
+#if TCP_OVERSIZE
+      LWIP_ASSERT("oversize == 0", oversize == 0);
+#endif /* TCP_OVERSIZE */
+      if ((p2 = pbuf_alloc(PBUF_TRANSPORT, seglen, PBUF_ROM)) == NULL) {
+        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for zero-copy pbuf\n"));
+        goto memerr;
+      }
+#if TCP_CHECKSUM_ON_COPY
+      /* calculate the checksum of nocopy-data */
+      chksum = ~inet_chksum((u8_t*)arg + pos, seglen);
+#endif /* TCP_CHECKSUM_ON_COPY */
+      /* reference the non-volatile payload data */
+      p2->payload = (u8_t*)arg + pos;
+
+      /* Second, allocate a pbuf for the headers. */
+      if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
+        /* If allocation fails, we have to deallocate the data pbuf as
+         * well. */
+        pbuf_free(p2);
+        LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: could not allocate memory for header pbuf\n"));
+        goto memerr;
+      }
+      /* Concatenate the headers and data pbufs together. */
+      pbuf_cat(p/*header*/, p2/*data*/);
+    }
+
+    queuelen += pbuf_clen(p);
+
+    /* Now that there are more segments queued, we check again if the
+     * length of the queue exceeds the configured maximum or
+     * overflows. */
+    if ((queuelen > TCP_SND_QUEUELEN) || (queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
+      LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 2, ("tcp_write: queue too long %"TCPWNDSIZE_F" (%"TCPWNDSIZE_F")\n", queuelen, TCP_SND_QUEUELEN));
+      pbuf_free(p);
+      goto memerr;
+    }
+
+    if ((seg = tcp_create_segment(pcb, p, 0, pcb->snd_lbb + pos, optflags)) == NULL) {
+      goto memerr;
+    }
+#if TCP_OVERSIZE_DBGCHECK
+    seg->oversize_left = oversize;
+#endif /* TCP_OVERSIZE_DBGCHECK */
+#if TCP_CHECKSUM_ON_COPY
+    seg->chksum = chksum;
+    seg->chksum_swapped = chksum_swapped;
+    seg->flags |= TF_SEG_DATA_CHECKSUMMED;
+#endif /* TCP_CHECKSUM_ON_COPY */
+
+    /* first segment of to-be-queued data? */
+    if (queue == NULL) {
+      queue = seg;
+    } else {
+      /* Attach the segment to the end of the queued segments */
+      LWIP_ASSERT("prev_seg != NULL", prev_seg != NULL);
+      prev_seg->next = seg;
+    }
+    /* remember last segment of to-be-queued data for next iteration */
+    prev_seg = seg;
+
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE, ("tcp_write: queueing %"U32_F":%"U32_F"\n",
+      ntohl(seg->tcphdr->seqno),
+      ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg)));
+
+    pos += seglen;
+  }
+
+  /*
+   * All three segmentation phases were successful. We can commit the
+   * transaction.
+   */
+
+  /*
+   * Phase 1: If data has been added to the preallocated tail of
+   * last_unsent, we update the length fields of the pbuf chain.
+   */
+#if TCP_OVERSIZE
+  if (oversize_used > 0) {
+    struct pbuf *p;
+    /* Bump tot_len of whole chain, len of tail */
+    for (p = last_unsent->p; p; p = p->next) {
+      p->tot_len += oversize_used;
+      if (p->next == NULL) {
+        TCP_DATA_COPY((char *)p->payload + p->len, arg, oversize_used, last_unsent);
+        p->len += oversize_used;
+      }
+    }
+    last_unsent->len += oversize_used;
+#if TCP_OVERSIZE_DBGCHECK
+    LWIP_ASSERT("last_unsent->oversize_left >= oversize_used",
+                last_unsent->oversize_left >= oversize_used);
+    last_unsent->oversize_left -= oversize_used;
+#endif /* TCP_OVERSIZE_DBGCHECK */
+  }
+  pcb->unsent_oversize = oversize;
+#endif /* TCP_OVERSIZE */
+
+  /*
+   * Phase 2: concat_p can be concatenated onto last_unsent->p
+   */
+  if (concat_p != NULL) {
+    LWIP_ASSERT("tcp_write: cannot concatenate when pcb->unsent is empty",
+      (last_unsent != NULL));
+    pbuf_cat(last_unsent->p, concat_p);
+    last_unsent->len += concat_p->tot_len;
+#if TCP_CHECKSUM_ON_COPY
+    if (concat_chksummed) {
+      tcp_seg_add_chksum(concat_chksum, concat_chksummed, &last_unsent->chksum,
+        &last_unsent->chksum_swapped);
+      last_unsent->flags |= TF_SEG_DATA_CHECKSUMMED;
+    }
+#endif /* TCP_CHECKSUM_ON_COPY */
+  }
+
+  /*
+   * Phase 3: Append queue to pcb->unsent. Queue may be NULL, but that
+   * is harmless
+   */
+  if (last_unsent == NULL) {
+    pcb->unsent = queue;
+  } else {
+    last_unsent->next = queue;
+  }
+
+  /*
+   * Finally update the pcb state.
+   */
+  pcb->snd_lbb += len;
+  pcb->snd_buf -= len;
+  pcb->snd_queuelen = queuelen;
+
+  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_write: %"S16_F" (after enqueued)\n",
+    pcb->snd_queuelen));
+  if (pcb->snd_queuelen != 0) {
+    LWIP_ASSERT("tcp_write: valid queue length",
+                pcb->unacked != NULL || pcb->unsent != NULL);
+  }
+
+  /* Set the PSH flag in the last segment that we enqueued. */
+  if (seg != NULL && seg->tcphdr != NULL && ((apiflags & TCP_WRITE_FLAG_MORE)==0)) {
+    TCPH_SET_FLAG(seg->tcphdr, TCP_PSH);
+  }
+
+  return ERR_OK;
+memerr:
+  pcb->flags |= TF_NAGLEMEMERR;
+  TCP_STATS_INC(tcp.memerr);
+
+  if (concat_p != NULL) {
+    pbuf_free(concat_p);
+  }
+  if (queue != NULL) {
+    tcp_segs_free(queue);
+  }
+  if (pcb->snd_queuelen != 0) {
+    LWIP_ASSERT("tcp_write: valid queue length", pcb->unacked != NULL ||
+      pcb->unsent != NULL);
+  }
+  LWIP_DEBUGF(TCP_QLEN_DEBUG | LWIP_DBG_STATE, ("tcp_write: %"S16_F" (with mem err)\n", pcb->snd_queuelen));
+  return ERR_MEM;
+}
+
+/**
+ * Enqueue TCP options for transmission.
+ *
+ * Called by tcp_connect(), tcp_listen_input(), and tcp_send_ctrl().
+ *
+ * @param pcb Protocol control block for the TCP connection.
+ * @param flags TCP header flags to set in the outgoing segment.
+ * @param optdata pointer to TCP options, or NULL.
+ * @param optlen length of TCP options in bytes.
+ */
+err_t
+tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags)
+{
+  struct pbuf *p;
+  struct tcp_seg *seg;
+  u8_t optflags = 0;
+  u8_t optlen = 0;
+
+  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: queuelen: %"U16_F"\n", (u16_t)pcb->snd_queuelen));
+
+  LWIP_ASSERT("tcp_enqueue_flags: need either TCP_SYN or TCP_FIN in flags (programmer violates API)",
+              (flags & (TCP_SYN | TCP_FIN)) != 0);
+
+  /* check for configured max queuelen and possible overflow */
+  if ((pcb->snd_queuelen >= TCP_SND_QUEUELEN) || (pcb->snd_queuelen > TCP_SNDQUEUELEN_OVERFLOW)) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: too long queue %"U16_F" (max %"U16_F")\n",
+                                       pcb->snd_queuelen, TCP_SND_QUEUELEN));
+    TCP_STATS_INC(tcp.memerr);
+    pcb->flags |= TF_NAGLEMEMERR;
+    return ERR_MEM;
+  }
+
+  if (flags & TCP_SYN) {
+    optflags = TF_SEG_OPTS_MSS;
+#if LWIP_WND_SCALE
+    if ((pcb->state != SYN_RCVD) || (pcb->flags & TF_WND_SCALE)) {
+      /* In a <SYN,ACK> (sent in state SYN_RCVD), the window scale option may only
+         be sent if we received a window scale option from the remote host. */
+      optflags |= TF_SEG_OPTS_WND_SCALE;
+    }
+#endif /* LWIP_WND_SCALE */
+  }
+#if LWIP_TCP_TIMESTAMPS
+  if ((pcb->flags & TF_TIMESTAMP)) {
+    optflags |= TF_SEG_OPTS_TS;
+  }
+#endif /* LWIP_TCP_TIMESTAMPS */
+  optlen = LWIP_TCP_OPT_LENGTH(optflags);
+
+  /* tcp_enqueue_flags is always called with either SYN or FIN in flags.
+   * We need one available snd_buf byte to do that.
+   * This means we can't send FIN while snd_buf==0. A better fix would be to
+   * not include SYN and FIN sequence numbers in the snd_buf count. */
+  if (pcb->snd_buf == 0) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG | 3, ("tcp_enqueue_flags: no send buffer available\n"));
+    TCP_STATS_INC(tcp.memerr);
+    return ERR_MEM;
+  }
+
+  /* Allocate pbuf with room for TCP header + options */
+  if ((p = pbuf_alloc(PBUF_TRANSPORT, optlen, PBUF_RAM)) == NULL) {
+    pcb->flags |= TF_NAGLEMEMERR;
+    TCP_STATS_INC(tcp.memerr);
+    return ERR_MEM;
+  }
+  LWIP_ASSERT("tcp_enqueue_flags: check that first pbuf can hold optlen",
+              (p->len >= optlen));
+
+  /* Allocate memory for tcp_seg, and fill in fields. */
+  if ((seg = tcp_create_segment(pcb, p, flags, pcb->snd_lbb, optflags)) == NULL) {
+    pcb->flags |= TF_NAGLEMEMERR;
+    TCP_STATS_INC(tcp.memerr);
+    return ERR_MEM;
+  }
+  LWIP_ASSERT("seg->tcphdr not aligned", ((mem_ptr_t)seg->tcphdr % MEM_ALIGNMENT) == 0);
+  LWIP_ASSERT("tcp_enqueue_flags: invalid segment length", seg->len == 0);
+
+  LWIP_DEBUGF(TCP_OUTPUT_DEBUG | LWIP_DBG_TRACE,
+              ("tcp_enqueue_flags: queueing %"U32_F":%"U32_F" (0x%"X16_F")\n",
+               ntohl(seg->tcphdr->seqno),
+               ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg),
+               (u16_t)flags));
+
+  /* Now append seg to pcb->unsent queue */
+  if (pcb->unsent == NULL) {
+    pcb->unsent = seg;
+  } else {
+    struct tcp_seg *useg;
+    for (useg = pcb->unsent; useg->next != NULL; useg = useg->next);
+    useg->next = seg;
+  }
+#if TCP_OVERSIZE
+  /* The new unsent tail has no space */
+  pcb->unsent_oversize = 0;
+#endif /* TCP_OVERSIZE */
+
+  /* SYN and FIN bump the sequence number */
+  if ((flags & TCP_SYN) || (flags & TCP_FIN)) {
+    pcb->snd_lbb++;
+    /* optlen does not influence snd_buf */
+    pcb->snd_buf--;
+  }
+  if (flags & TCP_FIN) {
+    pcb->flags |= TF_FIN;
+  }
+
+  /* update number of segments on the queues */
+  pcb->snd_queuelen += pbuf_clen(seg->p);
+  LWIP_DEBUGF(TCP_QLEN_DEBUG, ("tcp_enqueue_flags: %"S16_F" (after enqueued)\n", pcb->snd_queuelen));
+  if (pcb->snd_queuelen != 0) {
+    LWIP_ASSERT("tcp_enqueue_flags: invalid queue length",
+      pcb->unacked != NULL || pcb->unsent != NULL);
+  }
+
+  return ERR_OK;
+}
+
+#if LWIP_TCP_TIMESTAMPS
+/* Build a timestamp option (12 bytes long) at the specified options pointer)
+ *
+ * @param pcb tcp_pcb
+ * @param opts option pointer where to store the timestamp option
+ */
+static void
+tcp_build_timestamp_option(struct tcp_pcb *pcb, u32_t *opts)
+{
+  /* Pad with two NOP options to make everything nicely aligned */
+  opts[0] = PP_HTONL(0x0101080A);
+  opts[1] = htonl(sys_now());
+  opts[2] = htonl(pcb->ts_recent);
+}
+#endif
+
+#if LWIP_WND_SCALE
+/** Build a window scale option (3 bytes long) at the specified options pointer)
+ *
+ * @param opts option pointer where to store the window scale option
+ */
+static void
+tcp_build_wnd_scale_option(u32_t *opts)
+{
+  /* Pad with one NOP option to make everything nicely aligned */
+  opts[0] = PP_HTONL(0x01030300 | TCP_RCV_SCALE);
+}
+#endif
+
+/** Send an ACK without data.
+ *
+ * @param pcb Protocol control block for the TCP connection to send the ACK
+ */
+err_t
+tcp_send_empty_ack(struct tcp_pcb *pcb)
+{
+  struct pbuf *p;
+  u8_t optlen = 0;
+#if LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP
+  struct tcp_hdr *tcphdr;
+#endif /* LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP */
+
+#if LWIP_TCP_TIMESTAMPS
+  if (pcb->flags & TF_TIMESTAMP) {
+    optlen = LWIP_TCP_OPT_LENGTH(TF_SEG_OPTS_TS);
+  }
+#endif
+
+  p = tcp_output_alloc_header(pcb, optlen, 0, htonl(pcb->snd_nxt));
+  if (p == NULL) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: (ACK) could not allocate pbuf\n"));
+    return ERR_BUF;
+  }
+#if LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP
+  tcphdr = (struct tcp_hdr *)p->payload;
+#endif /* LWIP_TCP_TIMESTAMPS || CHECKSUM_GEN_TCP */
+  LWIP_DEBUGF(TCP_OUTPUT_DEBUG, 
+              ("tcp_output: sending ACK for %"U32_F"\n", pcb->rcv_nxt));
+  /* remove ACK flags from the PCB, as we send an empty ACK now */
+  pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
+
+  /* NB. MSS and window scale options are only sent on SYNs, so ignore them here */
+#if LWIP_TCP_TIMESTAMPS
+  pcb->ts_lastacksent = pcb->rcv_nxt;
+
+  if (pcb->flags & TF_TIMESTAMP) {
+    tcp_build_timestamp_option(pcb, (u32_t *)(tcphdr + 1));
+  }
+#endif 
+
+#if CHECKSUM_GEN_TCP
+  tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len,
+    &pcb->local_ip, &pcb->remote_ip);
+#endif
+#if LWIP_NETIF_HWADDRHINT
+  ipX_output_hinted(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, pcb->tos,
+      IP_PROTO_TCP, &pcb->addr_hint);
+#else /* LWIP_NETIF_HWADDRHINT*/
+  ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, pcb->tos,
+      IP_PROTO_TCP);
+#endif /* LWIP_NETIF_HWADDRHINT*/
+  pbuf_free(p);
+
+  return ERR_OK;
+}
+
+/**
+ * Find out what we can send and send it
+ *
+ * @param pcb Protocol control block for the TCP connection to send data
+ * @return ERR_OK if data has been sent or nothing to send
+ *         another err_t on error
+ */
+err_t
+tcp_output(struct tcp_pcb *pcb)
+{
+  struct tcp_seg *seg, *useg;
+  u32_t wnd, snd_nxt;
+#if TCP_CWND_DEBUG
+  s16_t i = 0;
+#endif /* TCP_CWND_DEBUG */
+
+  /* pcb->state LISTEN not allowed here */
+  LWIP_ASSERT("don't call tcp_output for listen-pcbs",
+    pcb->state != LISTEN);
+
+  /* First, check if we are invoked by the TCP input processing
+     code. If so, we do not output anything. Instead, we rely on the
+     input processing code to call us when input processing is done
+     with. */
+  if (tcp_input_pcb == pcb) {
+    return ERR_OK;
+  }
+
+  wnd = LWIP_MIN(pcb->snd_wnd, pcb->cwnd);
+
+  seg = pcb->unsent;
+
+  /* If the TF_ACK_NOW flag is set and no data will be sent (either
+   * because the ->unsent queue is empty or because the window does
+   * not allow it), construct an empty ACK segment and send it.
+   *
+   * If data is to be sent, we will just piggyback the ACK (see below).
+   */
+  if (pcb->flags & TF_ACK_NOW &&
+     (seg == NULL ||
+      ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len > wnd)) {
+     return tcp_send_empty_ack(pcb);
+  }
+
+  /* useg should point to last segment on unacked queue */
+  useg = pcb->unacked;
+  if (useg != NULL) {
+    for (; useg->next != NULL; useg = useg->next);
+  }
+
+#if TCP_OUTPUT_DEBUG
+  if (seg == NULL) {
+    LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output: nothing to send (%p)\n",
+                                   (void*)pcb->unsent));
+  }
+#endif /* TCP_OUTPUT_DEBUG */
+#if TCP_CWND_DEBUG
+  if (seg == NULL) {
+    LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"TCPWNDSIZE_F
+                                 ", cwnd %"TCPWNDSIZE_F", wnd %"U32_F
+                                 ", seg == NULL, ack %"U32_F"\n",
+                                 pcb->snd_wnd, pcb->cwnd, wnd, pcb->lastack));
+  } else {
+    LWIP_DEBUGF(TCP_CWND_DEBUG, 
+                ("tcp_output: snd_wnd %"TCPWNDSIZE_F", cwnd %"TCPWNDSIZE_F", wnd %"U32_F
+                 ", effwnd %"U32_F", seq %"U32_F", ack %"U32_F"\n",
+                 pcb->snd_wnd, pcb->cwnd, wnd,
+                 ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len,
+                 ntohl(seg->tcphdr->seqno), pcb->lastack));
+  }
+#endif /* TCP_CWND_DEBUG */
+  /* data available and window allows it to be sent? */
+  while (seg != NULL &&
+         ntohl(seg->tcphdr->seqno) - pcb->lastack + seg->len <= wnd) {
+    LWIP_ASSERT("RST not expected here!", 
+                (TCPH_FLAGS(seg->tcphdr) & TCP_RST) == 0);
+    /* Stop sending if the nagle algorithm would prevent it
+     * Don't stop:
+     * - if tcp_write had a memory error before (prevent delayed ACK timeout) or
+     * - if FIN was already enqueued for this PCB (SYN is always alone in a segment -
+     *   either seg->next != NULL or pcb->unacked == NULL;
+     *   RST is no sent using tcp_write/tcp_output.
+     */
+    if((tcp_do_output_nagle(pcb) == 0) &&
+      ((pcb->flags & (TF_NAGLEMEMERR | TF_FIN)) == 0)){
+      break;
+    }
+#if TCP_CWND_DEBUG
+    LWIP_DEBUGF(TCP_CWND_DEBUG, ("tcp_output: snd_wnd %"TCPWNDSIZE_F", cwnd %"TCPWNDSIZE_F", wnd %"U32_F", effwnd %"U32_F", seq %"U32_F", ack %"U32_F", i %"S16_F"\n",
+                            pcb->snd_wnd, pcb->cwnd, wnd,
+                            ntohl(seg->tcphdr->seqno) + seg->len -
+                            pcb->lastack,
+                            ntohl(seg->tcphdr->seqno), pcb->lastack, i));
+    ++i;
+#endif /* TCP_CWND_DEBUG */
+
+    pcb->unsent = seg->next;
+
+    if (pcb->state != SYN_SENT) {
+      TCPH_SET_FLAG(seg->tcphdr, TCP_ACK);
+      pcb->flags &= ~(TF_ACK_DELAY | TF_ACK_NOW);
+    }
+
+#if TCP_OVERSIZE_DBGCHECK
+    seg->oversize_left = 0;
+#endif /* TCP_OVERSIZE_DBGCHECK */
+    tcp_output_segment(seg, pcb);
+    snd_nxt = ntohl(seg->tcphdr->seqno) + TCP_TCPLEN(seg);
+    if (TCP_SEQ_LT(pcb->snd_nxt, snd_nxt)) {
+      pcb->snd_nxt = snd_nxt;
+    }
+    /* put segment on unacknowledged list if length > 0 */
+    if (TCP_TCPLEN(seg) > 0) {
+      seg->next = NULL;
+      /* unacked list is empty? */
+      if (pcb->unacked == NULL) {
+        pcb->unacked = seg;
+        useg = seg;
+      /* unacked list is not empty? */
+      } else {
+        /* In the case of fast retransmit, the packet should not go to the tail
+         * of the unacked queue, but rather somewhere before it. We need to check for
+         * this case. -STJ Jul 27, 2004 */
+        if (TCP_SEQ_LT(ntohl(seg->tcphdr->seqno), ntohl(useg->tcphdr->seqno))) {
+          /* add segment to before tail of unacked list, keeping the list sorted */
+          struct tcp_seg **cur_seg = &(pcb->unacked);
+          while (*cur_seg &&
+            TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
+              cur_seg = &((*cur_seg)->next );
+          }
+          seg->next = (*cur_seg);
+          (*cur_seg) = seg;
+        } else {
+          /* add segment to tail of unacked list */
+          useg->next = seg;
+          useg = useg->next;
+        }
+      }
+    /* do not queue empty segments on the unacked list */
+    } else {
+      tcp_seg_free(seg);
+    }
+    seg = pcb->unsent;
+  }
+#if TCP_OVERSIZE
+  if (pcb->unsent == NULL) {
+    /* last unsent has been removed, reset unsent_oversize */
+    pcb->unsent_oversize = 0;
+  }
+#endif /* TCP_OVERSIZE */
+
+  pcb->flags &= ~TF_NAGLEMEMERR;
+  return ERR_OK;
+}
+
+/**
+ * Called by tcp_output() to actually send a TCP segment over IP.
+ *
+ * @param seg the tcp_seg to send
+ * @param pcb the tcp_pcb for the TCP connection used to send the segment
+ */
+static void
+tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
+{
+  u16_t len;
+  u32_t *opts;
+
+  /** @bug Exclude retransmitted segments from this count. */
+  snmp_inc_tcpoutsegs();
+
+  /* The TCP header has already been constructed, but the ackno and
+   wnd fields remain. */
+  seg->tcphdr->ackno = htonl(pcb->rcv_nxt);
+
+  /* advertise our receive window size in this TCP segment */
+#if LWIP_WND_SCALE
+  if (seg->flags & TF_SEG_OPTS_WND_SCALE) {
+    /* The Window field in a SYN segment itself (the only type where we send
+       the window scale option) is never scaled. */
+    seg->tcphdr->wnd = htons(pcb->rcv_ann_wnd);
+  } else
+#endif /* LWIP_WND_SCALE */
+  {
+    seg->tcphdr->wnd = htons(RCV_WND_SCALE(pcb, pcb->rcv_ann_wnd));
+  }
+
+  pcb->rcv_ann_right_edge = pcb->rcv_nxt + pcb->rcv_ann_wnd;
+
+  /* Add any requested options.  NB MSS option is only set on SYN
+     packets, so ignore it here */
+  opts = (u32_t *)(void *)(seg->tcphdr + 1);
+  if (seg->flags & TF_SEG_OPTS_MSS) {
+    u16_t mss;
+#if TCP_CALCULATE_EFF_SEND_MSS
+    mss = tcp_eff_send_mss(TCP_MSS, &pcb->local_ip, &pcb->remote_ip, PCB_ISIPV6(pcb));
+#else /* TCP_CALCULATE_EFF_SEND_MSS */
+    mss = TCP_MSS;
+#endif /* TCP_CALCULATE_EFF_SEND_MSS */
+    *opts = TCP_BUILD_MSS_OPTION(mss);
+    opts += 1;
+  }
+#if LWIP_TCP_TIMESTAMPS
+  pcb->ts_lastacksent = pcb->rcv_nxt;
+
+  if (seg->flags & TF_SEG_OPTS_TS) {
+    tcp_build_timestamp_option(pcb, opts);
+    opts += 3;
+  }
+#endif
+#if LWIP_WND_SCALE
+  if (seg->flags & TF_SEG_OPTS_WND_SCALE) {
+    tcp_build_wnd_scale_option(opts);
+    opts += 1;
+  }
+#endif
+  
+  /* Set retransmission timer running if it is not currently enabled 
+     This must be set before checking the route. */
+  if (pcb->rtime == -1) {
+    pcb->rtime = 0;
+  }
+
+  /* If we don't have a local IP address, we get one by
+     calling ip_route(). */
+  if (ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) {
+    struct netif *netif;
+    ipX_addr_t *local_ip;
+    ipX_route_get_local_ipX(PCB_ISIPV6(pcb), &pcb->local_ip, &pcb->remote_ip, netif, local_ip);
+    if ((netif == NULL) || (local_ip == NULL)) {
+      return;
+    }
+    ipX_addr_copy(PCB_ISIPV6(pcb), pcb->local_ip, *local_ip);
+  }
+
+  if (pcb->rttest == 0) {
+    pcb->rttest = tcp_ticks;
+    pcb->rtseq = ntohl(seg->tcphdr->seqno);
+
+    LWIP_DEBUGF(TCP_RTO_DEBUG, ("tcp_output_segment: rtseq %"U32_F"\n", pcb->rtseq));
+  }
+  LWIP_DEBUGF(TCP_OUTPUT_DEBUG, ("tcp_output_segment: %"U32_F":%"U32_F"\n",
+          htonl(seg->tcphdr->seqno), htonl(seg->tcphdr->seqno) +
+          seg->len));
+
+  len = (u16_t)((u8_t *)seg->tcphdr - (u8_t *)seg->p->payload);
+
+  seg->p->len -= len;
+  seg->p->tot_len -= len;
+
+  seg->p->payload = seg->tcphdr;
+
+  seg->tcphdr->chksum = 0;
+#if TCP_CHECKSUM_ON_COPY
+  {
+    u32_t acc;
+#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
+    u16_t chksum_slow = ipX_chksum_pseudo(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP,
+      seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip);
+#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
+    if ((seg->flags & TF_SEG_DATA_CHECKSUMMED) == 0) {
+      LWIP_ASSERT("data included but not checksummed",
+        seg->p->tot_len == (TCPH_HDRLEN(seg->tcphdr) * 4));
+    }
+
+    /* rebuild TCP header checksum (TCP header changes for retransmissions!) */
+    acc = ipX_chksum_pseudo_partial(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP,
+      seg->p->tot_len, TCPH_HDRLEN(seg->tcphdr) * 4, &pcb->local_ip, &pcb->remote_ip);
+    /* add payload checksum */
+    if (seg->chksum_swapped) {
+      seg->chksum = SWAP_BYTES_IN_WORD(seg->chksum);
+      seg->chksum_swapped = 0;
+    }
+    acc += (u16_t)~(seg->chksum);
+    seg->tcphdr->chksum = FOLD_U32T(acc);
+#if TCP_CHECKSUM_ON_COPY_SANITY_CHECK
+    if (chksum_slow != seg->tcphdr->chksum) {
+      LWIP_DEBUGF(TCP_DEBUG | LWIP_DBG_LEVEL_WARNING,
+                  ("tcp_output_segment: calculated checksum is %"X16_F" instead of %"X16_F"\n",
+                  seg->tcphdr->chksum, chksum_slow));
+      seg->tcphdr->chksum = chksum_slow;
+    }
+#endif /* TCP_CHECKSUM_ON_COPY_SANITY_CHECK */
+  }
+#else /* TCP_CHECKSUM_ON_COPY */
+#if CHECKSUM_GEN_TCP
+  seg->tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), seg->p, IP_PROTO_TCP,
+    seg->p->tot_len, &pcb->local_ip, &pcb->remote_ip);
+#endif /* CHECKSUM_GEN_TCP */
+#endif /* TCP_CHECKSUM_ON_COPY */
+  TCP_STATS_INC(tcp.xmit);
+
+#if LWIP_NETIF_HWADDRHINT
+  ipX_output_hinted(PCB_ISIPV6(pcb), seg->p, &pcb->local_ip, &pcb->remote_ip,
+    pcb->ttl, pcb->tos, IP_PROTO_TCP, &pcb->addr_hint);
+#else /* LWIP_NETIF_HWADDRHINT*/
+  ipX_output(PCB_ISIPV6(pcb), seg->p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
+    pcb->tos, IP_PROTO_TCP);
+#endif /* LWIP_NETIF_HWADDRHINT*/
+}
+
+/**
+ * Send a TCP RESET packet (empty segment with RST flag set) either to
+ * abort a connection or to show that there is no matching local connection
+ * for a received segment.
+ *
+ * Called by tcp_abort() (to abort a local connection), tcp_input() (if no
+ * matching local pcb was found), tcp_listen_input() (if incoming segment
+ * has ACK flag set) and tcp_process() (received segment in the wrong state)
+ *
+ * Since a RST segment is in most cases not sent for an active connection,
+ * tcp_rst() has a number of arguments that are taken from a tcp_pcb for
+ * most other segment output functions.
+ *
+ * @param seqno the sequence number to use for the outgoing segment
+ * @param ackno the acknowledge number to use for the outgoing segment
+ * @param local_ip the local IP address to send the segment from
+ * @param remote_ip the remote IP address to send the segment to
+ * @param local_port the local TCP port to send the segment from
+ * @param remote_port the remote TCP port to send the segment to
+ */
+void
+tcp_rst_impl(u32_t seqno, u32_t ackno,
+  ipX_addr_t *local_ip, ipX_addr_t *remote_ip,
+  u16_t local_port, u16_t remote_port
+#if LWIP_IPV6
+  , u8_t isipv6
+#endif /* LWIP_IPV6 */
+  )
+{
+  struct pbuf *p;
+  struct tcp_hdr *tcphdr;
+  p = pbuf_alloc(PBUF_IP, TCP_HLEN, PBUF_RAM);
+  if (p == NULL) {
+      LWIP_DEBUGF(TCP_DEBUG, ("tcp_rst: could not allocate memory for pbuf\n"));
+      return;
+  }
+  LWIP_ASSERT("check that first pbuf can hold struct tcp_hdr",
+              (p->len >= sizeof(struct tcp_hdr)));
+
+  tcphdr = (struct tcp_hdr *)p->payload;
+  tcphdr->src = htons(local_port);
+  tcphdr->dest = htons(remote_port);
+  tcphdr->seqno = htonl(seqno);
+  tcphdr->ackno = htonl(ackno);
+  TCPH_HDRLEN_FLAGS_SET(tcphdr, TCP_HLEN/4, TCP_RST | TCP_ACK);
+#if LWIP_WND_SCALE
+  tcphdr->wnd = PP_HTONS(((TCP_WND >> TCP_RCV_SCALE) & 0xFFFF));
+#else
+  tcphdr->wnd = PP_HTONS(TCP_WND);
+#endif
+  tcphdr->chksum = 0;
+  tcphdr->urgp = 0;
+
+  TCP_STATS_INC(tcp.xmit);
+  snmp_inc_tcpoutrsts();
+
+#if CHECKSUM_GEN_TCP
+  tcphdr->chksum = ipX_chksum_pseudo(isipv6, p, IP_PROTO_TCP, p->tot_len,
+                                     local_ip, remote_ip);
+#endif
+  /* Send output with hardcoded TTL/HL since we have no access to the pcb */
+  ipX_output(isipv6, p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
+  pbuf_free(p);
+  LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_rst: seqno %"U32_F" ackno %"U32_F".\n", seqno, ackno));
+}
+
+/**
+ * Requeue all unacked segments for retransmission
+ *
+ * Called by tcp_slowtmr() for slow retransmission.
+ *
+ * @param pcb the tcp_pcb for which to re-enqueue all unacked segments
+ */
+void
+tcp_rexmit_rto(struct tcp_pcb *pcb)
+{
+  struct tcp_seg *seg;
+
+  if (pcb->unacked == NULL) {
+    return;
+  }
+
+  /* Move all unacked segments to the head of the unsent queue */
+  for (seg = pcb->unacked; seg->next != NULL; seg = seg->next);
+  /* concatenate unsent queue after unacked queue */
+  seg->next = pcb->unsent;
+#if TCP_OVERSIZE && TCP_OVERSIZE_DBGCHECK
+  /* if last unsent changed, we need to update unsent_oversize */
+  if (pcb->unsent == NULL) {
+    pcb->unsent_oversize = seg->oversize_left;
+  }
+#endif /* TCP_OVERSIZE && TCP_OVERSIZE_DBGCHECK*/
+  /* unsent queue is the concatenated queue (of unacked, unsent) */
+  pcb->unsent = pcb->unacked;
+  /* unacked queue is now empty */
+  pcb->unacked = NULL;
+
+  /* increment number of retransmissions */
+  ++pcb->nrtx;
+
+  /* Don't take any RTT measurements after retransmitting. */
+  pcb->rttest = 0;
+
+  /* Do the actual retransmission */
+  tcp_output(pcb);
+}
+
+/**
+ * Requeue the first unacked segment for retransmission
+ *
+ * Called by tcp_receive() for fast retramsmit.
+ *
+ * @param pcb the tcp_pcb for which to retransmit the first unacked segment
+ */
+void
+tcp_rexmit(struct tcp_pcb *pcb)
+{
+  struct tcp_seg *seg;
+  struct tcp_seg **cur_seg;
+
+  if (pcb->unacked == NULL) {
+    return;
+  }
+
+  /* Move the first unacked segment to the unsent queue */
+  /* Keep the unsent queue sorted. */
+  seg = pcb->unacked;
+  pcb->unacked = seg->next;
+
+  cur_seg = &(pcb->unsent);
+  while (*cur_seg &&
+    TCP_SEQ_LT(ntohl((*cur_seg)->tcphdr->seqno), ntohl(seg->tcphdr->seqno))) {
+      cur_seg = &((*cur_seg)->next );
+  }
+  seg->next = *cur_seg;
+  *cur_seg = seg;
+#if TCP_OVERSIZE
+  if (seg->next == NULL) {
+    /* the retransmitted segment is last in unsent, so reset unsent_oversize */
+    pcb->unsent_oversize = 0;
+  }
+#endif /* TCP_OVERSIZE */
+
+  ++pcb->nrtx;
+
+  /* Don't take any rtt measurements after retransmitting. */
+  pcb->rttest = 0;
+
+  /* Do the actual retransmission. */
+  snmp_inc_tcpretranssegs();
+  /* No need to call tcp_output: we are always called from tcp_input()
+     and thus tcp_output directly returns. */
+}
+
+
+/**
+ * Handle retransmission after three dupacks received
+ *
+ * @param pcb the tcp_pcb for which to retransmit the first unacked segment
+ */
+void 
+tcp_rexmit_fast(struct tcp_pcb *pcb)
+{
+  if (pcb->unacked != NULL && !(pcb->flags & TF_INFR)) {
+    /* This is fast retransmit. Retransmit the first unacked segment. */
+    LWIP_DEBUGF(TCP_FR_DEBUG, 
+                ("tcp_receive: dupacks %"U16_F" (%"U32_F
+                 "), fast retransmit %"U32_F"\n",
+                 (u16_t)pcb->dupacks, pcb->lastack,
+                 ntohl(pcb->unacked->tcphdr->seqno)));
+    tcp_rexmit(pcb);
+
+    /* Set ssthresh to half of the minimum of the current
+     * cwnd and the advertised window */
+    if (pcb->cwnd > pcb->snd_wnd) {
+      pcb->ssthresh = pcb->snd_wnd / 2;
+    } else {
+      pcb->ssthresh = pcb->cwnd / 2;
+    }
+    
+    /* The minimum value for ssthresh should be 2 MSS */
+    if (pcb->ssthresh < (2U * pcb->mss)) {
+      LWIP_DEBUGF(TCP_FR_DEBUG, 
+                  ("tcp_receive: The minimum value for ssthresh %"U16_F
+                   " should be min 2 mss %"U16_F"...\n",
+                   pcb->ssthresh, 2*pcb->mss));
+      pcb->ssthresh = 2*pcb->mss;
+    }
+    
+    pcb->cwnd = pcb->ssthresh + 3 * pcb->mss;
+    pcb->flags |= TF_INFR;
+  } 
+}
+
+
+/**
+ * Send keepalive packets to keep a connection active although
+ * no data is sent over it.
+ *
+ * Called by tcp_slowtmr()
+ *
+ * @param pcb the tcp_pcb for which to send a keepalive packet
+ */
+void
+tcp_keepalive(struct tcp_pcb *pcb)
+{
+  struct pbuf *p;
+#if CHECKSUM_GEN_TCP
+  struct tcp_hdr *tcphdr;
+#endif /* CHECKSUM_GEN_TCP */
+
+  LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: sending KEEPALIVE probe to "));
+  ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip);
+  LWIP_DEBUGF(TCP_DEBUG, ("\n"));
+
+  LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: tcp_ticks %"U32_F"   pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n", 
+                          tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
+   
+  p = tcp_output_alloc_header(pcb, 0, 0, htonl(pcb->snd_nxt - 1));
+  if(p == NULL) {
+    LWIP_DEBUGF(TCP_DEBUG, 
+                ("tcp_keepalive: could not allocate memory for pbuf\n"));
+    return;
+  }
+#if CHECKSUM_GEN_TCP
+  tcphdr = (struct tcp_hdr *)p->payload;
+
+  tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len,
+      &pcb->local_ip, &pcb->remote_ip);
+#endif /* CHECKSUM_GEN_TCP */
+  TCP_STATS_INC(tcp.xmit);
+
+  /* Send output to IP */
+#if LWIP_NETIF_HWADDRHINT
+  ipX_output_hinted(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip,
+    pcb->ttl, 0, IP_PROTO_TCP, &pcb->addr_hint);
+#else /* LWIP_NETIF_HWADDRHINT*/
+  ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
+    0, IP_PROTO_TCP);
+#endif /* LWIP_NETIF_HWADDRHINT*/
+
+  pbuf_free(p);
+
+  LWIP_DEBUGF(TCP_DEBUG, ("tcp_keepalive: seqno %"U32_F" ackno %"U32_F".\n",
+                          pcb->snd_nxt - 1, pcb->rcv_nxt));
+}
+
+
+/**
+ * Send persist timer zero-window probes to keep a connection active
+ * when a window update is lost.
+ *
+ * Called by tcp_slowtmr()
+ *
+ * @param pcb the tcp_pcb for which to send a zero-window probe packet
+ */
+void
+tcp_zero_window_probe(struct tcp_pcb *pcb)
+{
+  struct pbuf *p;
+  struct tcp_hdr *tcphdr;
+  struct tcp_seg *seg;
+  u16_t len;
+  u8_t is_fin;
+
+  LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: sending ZERO WINDOW probe to "));
+  ipX_addr_debug_print(PCB_ISIPV6(pcb), TCP_DEBUG, &pcb->remote_ip);
+  LWIP_DEBUGF(TCP_DEBUG, ("\n"));
+
+  LWIP_DEBUGF(TCP_DEBUG, 
+              ("tcp_zero_window_probe: tcp_ticks %"U32_F
+               "   pcb->tmr %"U32_F" pcb->keep_cnt_sent %"U16_F"\n", 
+               tcp_ticks, pcb->tmr, pcb->keep_cnt_sent));
+
+  seg = pcb->unacked;
+
+  if(seg == NULL) {
+    seg = pcb->unsent;
+  }
+  if(seg == NULL) {
+    return;
+  }
+
+  is_fin = ((TCPH_FLAGS(seg->tcphdr) & TCP_FIN) != 0) && (seg->len == 0);
+  /* we want to send one seqno: either FIN or data (no options) */
+  len = is_fin ? 0 : 1;
+
+  p = tcp_output_alloc_header(pcb, 0, len, seg->tcphdr->seqno);
+  if(p == NULL) {
+    LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: no memory for pbuf\n"));
+    return;
+  }
+  tcphdr = (struct tcp_hdr *)p->payload;
+
+  if (is_fin) {
+    /* FIN segment, no data */
+    TCPH_FLAGS_SET(tcphdr, TCP_ACK | TCP_FIN);
+  } else {
+    /* Data segment, copy in one byte from the head of the unacked queue */
+    char *d = ((char *)p->payload + TCP_HLEN);
+    /* Depending on whether the segment has already been sent (unacked) or not
+       (unsent), seg->p->payload points to the IP header or TCP header.
+       Ensure we copy the first TCP data byte: */
+    pbuf_copy_partial(seg->p, d, 1, seg->p->tot_len - seg->len);
+  }
+
+#if CHECKSUM_GEN_TCP
+  tcphdr->chksum = ipX_chksum_pseudo(PCB_ISIPV6(pcb), p, IP_PROTO_TCP, p->tot_len,
+      &pcb->local_ip, &pcb->remote_ip);
+#endif
+  TCP_STATS_INC(tcp.xmit);
+
+  /* Send output to IP */
+#if LWIP_NETIF_HWADDRHINT
+  ipX_output_hinted(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl,
+    0, IP_PROTO_TCP, &pcb->addr_hint);
+#else /* LWIP_NETIF_HWADDRHINT*/
+  ipX_output(PCB_ISIPV6(pcb), p, &pcb->local_ip, &pcb->remote_ip, pcb->ttl, 0, IP_PROTO_TCP);
+#endif /* LWIP_NETIF_HWADDRHINT*/
+
+  pbuf_free(p);
+
+  LWIP_DEBUGF(TCP_DEBUG, ("tcp_zero_window_probe: seqno %"U32_F
+                          " ackno %"U32_F".\n",
+                          pcb->snd_nxt - 1, pcb->rcv_nxt));
+}
+#endif /* LWIP_TCP */
diff --git a/src/include/ipv4/lwip/inet.h b/src/include/ipv4/lwip/inet.h
index b19cad96..a6d2eda4 100644
--- a/src/include/ipv4/lwip/inet.h
+++ b/src/include/ipv4/lwip/inet.h
@@ -94,12 +94,12 @@ struct in_addr {
 
 #define IN_LOOPBACKNET      IP_LOOPBACKNET
 
-#ifndef INET_ADDRSTRLEN
-#define INET_ADDRSTRLEN     IP4ADDR_STRLEN_MAX
+#ifndef INET_ADDRSTRLEN
+#define INET_ADDRSTRLEN     IP4ADDR_STRLEN_MAX
 #endif
 #if LWIP_IPV6
-#ifndef INET6_ADDRSTRLEN
-#define INET6_ADDRSTRLEN    IP6ADDR_STRLEN_MAX
+#ifndef INET6_ADDRSTRLEN
+#define INET6_ADDRSTRLEN    IP6ADDR_STRLEN_MAX
 #endif
 #endif
 
diff --git a/src/include/ipv4/lwip/ip4_addr.h b/src/include/ipv4/lwip/ip4_addr.h
index e3833a6f..af76856c 100644
--- a/src/include/ipv4/lwip/ip4_addr.h
+++ b/src/include/ipv4/lwip/ip4_addr.h
@@ -1,247 +1,247 @@
-/*
- * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- *
- * Author: Adam Dunkels <adam@sics.se>
- *
- */
-#ifndef __LWIP_IP4_ADDR_H__
-#define __LWIP_IP4_ADDR_H__
-
-#include "lwip/opt.h"
-#include "lwip/def.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/* This is the aligned version of ip_addr_t,
-   used as local variable, on the stack, etc. */
-struct ip_addr {
-  u32_t addr;
-};
-
-/* This is the packed version of ip_addr_t,
-   used in network headers that are itself packed */
-#ifdef PACK_STRUCT_USE_INCLUDES
-#  include "arch/bpstruct.h"
-#endif
-PACK_STRUCT_BEGIN
-struct ip_addr_packed {
-  PACK_STRUCT_FIELD(u32_t addr);
-} PACK_STRUCT_STRUCT;
-PACK_STRUCT_END
-#ifdef PACK_STRUCT_USE_INCLUDES
-#  include "arch/epstruct.h"
-#endif
-
-/** ip_addr_t uses a struct for convenience only, so that the same defines can
- * operate both on ip_addr_t as well as on ip_addr_p_t. */
-typedef struct ip_addr ip_addr_t;
-typedef struct ip_addr_packed ip_addr_p_t;
-
-/*
- * struct ipaddr2 is used in the definition of the ARP packet format in
- * order to support compilers that don't have structure packing.
- */
-#ifdef PACK_STRUCT_USE_INCLUDES
-#  include "arch/bpstruct.h"
-#endif
-PACK_STRUCT_BEGIN
-struct ip_addr2 {
-  PACK_STRUCT_FIELD(u16_t addrw[2]);
-} PACK_STRUCT_STRUCT;
-PACK_STRUCT_END
-#ifdef PACK_STRUCT_USE_INCLUDES
-#  include "arch/epstruct.h"
-#endif
-
-/* Forward declaration to not include netif.h */
-struct netif;
-
-extern const ip_addr_t ip_addr_any;
-extern const ip_addr_t ip_addr_broadcast;
-
-/** IP_ADDR_ can be used as a fixed IP address
- *  for the wildcard and the broadcast address
- */
-#define IP_ADDR_ANY         ((ip_addr_t *)&ip_addr_any)
-#define IP_ADDR_BROADCAST   ((ip_addr_t *)&ip_addr_broadcast)
-
-/** 255.255.255.255 */
-#define IPADDR_NONE         ((u32_t)0xffffffffUL)
-/** 127.0.0.1 */
-#define IPADDR_LOOPBACK     ((u32_t)0x7f000001UL)
-/** 0.0.0.0 */
-#define IPADDR_ANY          ((u32_t)0x00000000UL)
-/** 255.255.255.255 */
-#define IPADDR_BROADCAST    ((u32_t)0xffffffffUL)
-
-/* Definitions of the bits in an Internet address integer.
-
-   On subnets, host and network parts are found according to
-   the subnet mask, not these masks.  */
-#define IP_CLASSA(a)        ((((u32_t)(a)) & 0x80000000UL) == 0)
-#define IP_CLASSA_NET       0xff000000
-#define IP_CLASSA_NSHIFT    24
-#define IP_CLASSA_HOST      (0xffffffff & ~IP_CLASSA_NET)
-#define IP_CLASSA_MAX       128
-
-#define IP_CLASSB(a)        ((((u32_t)(a)) & 0xc0000000UL) == 0x80000000UL)
-#define IP_CLASSB_NET       0xffff0000
-#define IP_CLASSB_NSHIFT    16
-#define IP_CLASSB_HOST      (0xffffffff & ~IP_CLASSB_NET)
-#define IP_CLASSB_MAX       65536
-
-#define IP_CLASSC(a)        ((((u32_t)(a)) & 0xe0000000UL) == 0xc0000000UL)
-#define IP_CLASSC_NET       0xffffff00
-#define IP_CLASSC_NSHIFT    8
-#define IP_CLASSC_HOST      (0xffffffff & ~IP_CLASSC_NET)
-
-#define IP_CLASSD(a)        (((u32_t)(a) & 0xf0000000UL) == 0xe0000000UL)
-#define IP_CLASSD_NET       0xf0000000          /* These ones aren't really */
-#define IP_CLASSD_NSHIFT    28                  /*   net and host fields, but */
-#define IP_CLASSD_HOST      0x0fffffff          /*   routing needn't know. */
-#define IP_MULTICAST(a)     IP_CLASSD(a)
-
-#define IP_EXPERIMENTAL(a)  (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
-#define IP_BADCLASS(a)      (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
-
-#define IP_LOOPBACKNET      127                 /* official! */
-
-
-#if BYTE_ORDER == BIG_ENDIAN
-/** Set an IP address given by the four byte-parts */
-#define IP4_ADDR(ipaddr, a,b,c,d) \
-        (ipaddr)->addr = ((u32_t)((a) & 0xff) << 24) | \
-                         ((u32_t)((b) & 0xff) << 16) | \
-                         ((u32_t)((c) & 0xff) << 8)  | \
-                          (u32_t)((d) & 0xff)
-#else
-/** Set an IP address given by the four byte-parts.
-    Little-endian version that prevents the use of htonl. */
-#define IP4_ADDR(ipaddr, a,b,c,d) \
-        (ipaddr)->addr = ((u32_t)((d) & 0xff) << 24) | \
-                         ((u32_t)((c) & 0xff) << 16) | \
-                         ((u32_t)((b) & 0xff) << 8)  | \
-                          (u32_t)((a) & 0xff)
-#endif
-
-/** MEMCPY-like copying of IP addresses where addresses are known to be
- * 16-bit-aligned if the port is correctly configured (so a port could define
- * this to copying 2 u16_t's) - no NULL-pointer-checking needed. */
-#ifndef IPADDR2_COPY
-#define IPADDR2_COPY(dest, src) SMEMCPY(dest, src, sizeof(ip_addr_t))
-#endif
-
-/** Copy IP address - faster than ip_addr_set: no NULL check */
-#define ip_addr_copy(dest, src) ((dest).addr = (src).addr)
-/** Safely copy one IP address to another (src may be NULL) */
-#define ip_addr_set(dest, src) ((dest)->addr = \
-                                    ((src) == NULL ? 0 : \
-                                    (src)->addr))
-/** Set complete address to zero */
-#define ip_addr_set_zero(ipaddr)      ((ipaddr)->addr = 0)
-/** Set address to IPADDR_ANY (no need for htonl()) */
-#define ip_addr_set_any(ipaddr)       ((ipaddr)->addr = IPADDR_ANY)
-/** Set address to loopback address */
-#define ip_addr_set_loopback(ipaddr)  ((ipaddr)->addr = PP_HTONL(IPADDR_LOOPBACK))
-/** Safely copy one IP address to another and change byte order
- * from host- to network-order. */
-#define ip_addr_set_hton(dest, src) ((dest)->addr = \
-                               ((src) == NULL ? 0:\
-                               htonl((src)->addr)))
-/** IPv4 only: set the IP address given as an u32_t */
-#define ip4_addr_set_u32(dest_ipaddr, src_u32) ((dest_ipaddr)->addr = (src_u32))
-/** IPv4 only: get the IP address as an u32_t */
-#define ip4_addr_get_u32(src_ipaddr) ((src_ipaddr)->addr)
-
-/** Get the network address by combining host address with netmask */
-#define ip_addr_get_network(target, host, netmask) ((target)->addr = ((host)->addr) & ((netmask)->addr))
-
-/**
- * Determine if two address are on the same network.
- *
- * @arg addr1 IP address 1
- * @arg addr2 IP address 2
- * @arg mask network identifier mask
- * @return !0 if the network identifiers of both address match
- */
-#define ip_addr_netcmp(addr1, addr2, mask) (((addr1)->addr & \
-                                              (mask)->addr) == \
-                                             ((addr2)->addr & \
-                                              (mask)->addr))
-#define ip_addr_cmp(addr1, addr2) ((addr1)->addr == (addr2)->addr)
-
-#define ip_addr_isany(addr1) ((addr1) == NULL || (addr1)->addr == IPADDR_ANY)
-
-#define ip_addr_isbroadcast(ipaddr, netif) ip4_addr_isbroadcast((ipaddr)->addr, (netif))
-u8_t ip4_addr_isbroadcast(u32_t addr, const struct netif *netif);
-
-#define ip_addr_netmask_valid(netmask) ip4_addr_netmask_valid((netmask)->addr)
-u8_t ip4_addr_netmask_valid(u32_t netmask);
-
-#define ip_addr_ismulticast(addr1) (((addr1)->addr & PP_HTONL(0xf0000000UL)) == PP_HTONL(0xe0000000UL))
-
-#define ip_addr_islinklocal(addr1) (((addr1)->addr & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xa9fe0000UL))
-
-#define ip_addr_debug_print(debug, ipaddr) \
-  LWIP_DEBUGF(debug, ("%" U16_F ".%" U16_F ".%" U16_F ".%" U16_F,      \
-                      ipaddr != NULL ? ip4_addr1_16(ipaddr) : 0,       \
-                      ipaddr != NULL ? ip4_addr2_16(ipaddr) : 0,       \
-                      ipaddr != NULL ? ip4_addr3_16(ipaddr) : 0,       \
-                      ipaddr != NULL ? ip4_addr4_16(ipaddr) : 0))
-
-/* Get one byte from the 4-byte address */
-#define ip4_addr1(ipaddr) (((u8_t*)(ipaddr))[0])
-#define ip4_addr2(ipaddr) (((u8_t*)(ipaddr))[1])
-#define ip4_addr3(ipaddr) (((u8_t*)(ipaddr))[2])
-#define ip4_addr4(ipaddr) (((u8_t*)(ipaddr))[3])
-/* These are cast to u16_t, with the intent that they are often arguments
- * to printf using the U16_F format from cc.h. */
-#define ip4_addr1_16(ipaddr) ((u16_t)ip4_addr1(ipaddr))
-#define ip4_addr2_16(ipaddr) ((u16_t)ip4_addr2(ipaddr))
-#define ip4_addr3_16(ipaddr) ((u16_t)ip4_addr3(ipaddr))
-#define ip4_addr4_16(ipaddr) ((u16_t)ip4_addr4(ipaddr))
-
-#define IP4ADDR_STRLEN_MAX  16
-#define IPADDR_STRLEN_MAX   IP4ADDR_STRLEN_MAX
-
-/** For backwards compatibility */
-#define ip_ntoa(ipaddr)  ipaddr_ntoa(ipaddr)
-
-u32_t ipaddr_addr(const char *cp);
-int ipaddr_aton(const char *cp, ip_addr_t *addr);
-/** returns ptr to static buffer; not reentrant! */
-char *ipaddr_ntoa(const ip_addr_t *addr);
-char *ipaddr_ntoa_r(const ip_addr_t *addr, char *buf, int buflen);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* __LWIP_IP_ADDR_H__ */
+/*
+ * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ *
+ * Author: Adam Dunkels <adam@sics.se>
+ *
+ */
+#ifndef __LWIP_IP4_ADDR_H__
+#define __LWIP_IP4_ADDR_H__
+
+#include "lwip/opt.h"
+#include "lwip/def.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* This is the aligned version of ip_addr_t,
+   used as local variable, on the stack, etc. */
+struct ip_addr {
+  u32_t addr;
+};
+
+/* This is the packed version of ip_addr_t,
+   used in network headers that are itself packed */
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
+struct ip_addr_packed {
+  PACK_STRUCT_FIELD(u32_t addr);
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
+
+/** ip_addr_t uses a struct for convenience only, so that the same defines can
+ * operate both on ip_addr_t as well as on ip_addr_p_t. */
+typedef struct ip_addr ip_addr_t;
+typedef struct ip_addr_packed ip_addr_p_t;
+
+/*
+ * struct ipaddr2 is used in the definition of the ARP packet format in
+ * order to support compilers that don't have structure packing.
+ */
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
+struct ip_addr2 {
+  PACK_STRUCT_FIELD(u16_t addrw[2]);
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
+
+/* Forward declaration to not include netif.h */
+struct netif;
+
+extern const ip_addr_t ip_addr_any;
+extern const ip_addr_t ip_addr_broadcast;
+
+/** IP_ADDR_ can be used as a fixed IP address
+ *  for the wildcard and the broadcast address
+ */
+#define IP_ADDR_ANY         ((ip_addr_t *)&ip_addr_any)
+#define IP_ADDR_BROADCAST   ((ip_addr_t *)&ip_addr_broadcast)
+
+/** 255.255.255.255 */
+#define IPADDR_NONE         ((u32_t)0xffffffffUL)
+/** 127.0.0.1 */
+#define IPADDR_LOOPBACK     ((u32_t)0x7f000001UL)
+/** 0.0.0.0 */
+#define IPADDR_ANY          ((u32_t)0x00000000UL)
+/** 255.255.255.255 */
+#define IPADDR_BROADCAST    ((u32_t)0xffffffffUL)
+
+/* Definitions of the bits in an Internet address integer.
+
+   On subnets, host and network parts are found according to
+   the subnet mask, not these masks.  */
+#define IP_CLASSA(a)        ((((u32_t)(a)) & 0x80000000UL) == 0)
+#define IP_CLASSA_NET       0xff000000
+#define IP_CLASSA_NSHIFT    24
+#define IP_CLASSA_HOST      (0xffffffff & ~IP_CLASSA_NET)
+#define IP_CLASSA_MAX       128
+
+#define IP_CLASSB(a)        ((((u32_t)(a)) & 0xc0000000UL) == 0x80000000UL)
+#define IP_CLASSB_NET       0xffff0000
+#define IP_CLASSB_NSHIFT    16
+#define IP_CLASSB_HOST      (0xffffffff & ~IP_CLASSB_NET)
+#define IP_CLASSB_MAX       65536
+
+#define IP_CLASSC(a)        ((((u32_t)(a)) & 0xe0000000UL) == 0xc0000000UL)
+#define IP_CLASSC_NET       0xffffff00
+#define IP_CLASSC_NSHIFT    8
+#define IP_CLASSC_HOST      (0xffffffff & ~IP_CLASSC_NET)
+
+#define IP_CLASSD(a)        (((u32_t)(a) & 0xf0000000UL) == 0xe0000000UL)
+#define IP_CLASSD_NET       0xf0000000          /* These ones aren't really */
+#define IP_CLASSD_NSHIFT    28                  /*   net and host fields, but */
+#define IP_CLASSD_HOST      0x0fffffff          /*   routing needn't know. */
+#define IP_MULTICAST(a)     IP_CLASSD(a)
+
+#define IP_EXPERIMENTAL(a)  (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
+#define IP_BADCLASS(a)      (((u32_t)(a) & 0xf0000000UL) == 0xf0000000UL)
+
+#define IP_LOOPBACKNET      127                 /* official! */
+
+
+#if BYTE_ORDER == BIG_ENDIAN
+/** Set an IP address given by the four byte-parts */
+#define IP4_ADDR(ipaddr, a,b,c,d) \
+        (ipaddr)->addr = ((u32_t)((a) & 0xff) << 24) | \
+                         ((u32_t)((b) & 0xff) << 16) | \
+                         ((u32_t)((c) & 0xff) << 8)  | \
+                          (u32_t)((d) & 0xff)
+#else
+/** Set an IP address given by the four byte-parts.
+    Little-endian version that prevents the use of htonl. */
+#define IP4_ADDR(ipaddr, a,b,c,d) \
+        (ipaddr)->addr = ((u32_t)((d) & 0xff) << 24) | \
+                         ((u32_t)((c) & 0xff) << 16) | \
+                         ((u32_t)((b) & 0xff) << 8)  | \
+                          (u32_t)((a) & 0xff)
+#endif
+
+/** MEMCPY-like copying of IP addresses where addresses are known to be
+ * 16-bit-aligned if the port is correctly configured (so a port could define
+ * this to copying 2 u16_t's) - no NULL-pointer-checking needed. */
+#ifndef IPADDR2_COPY
+#define IPADDR2_COPY(dest, src) SMEMCPY(dest, src, sizeof(ip_addr_t))
+#endif
+
+/** Copy IP address - faster than ip_addr_set: no NULL check */
+#define ip_addr_copy(dest, src) ((dest).addr = (src).addr)
+/** Safely copy one IP address to another (src may be NULL) */
+#define ip_addr_set(dest, src) ((dest)->addr = \
+                                    ((src) == NULL ? 0 : \
+                                    (src)->addr))
+/** Set complete address to zero */
+#define ip_addr_set_zero(ipaddr)      ((ipaddr)->addr = 0)
+/** Set address to IPADDR_ANY (no need for htonl()) */
+#define ip_addr_set_any(ipaddr)       ((ipaddr)->addr = IPADDR_ANY)
+/** Set address to loopback address */
+#define ip_addr_set_loopback(ipaddr)  ((ipaddr)->addr = PP_HTONL(IPADDR_LOOPBACK))
+/** Safely copy one IP address to another and change byte order
+ * from host- to network-order. */
+#define ip_addr_set_hton(dest, src) ((dest)->addr = \
+                               ((src) == NULL ? 0:\
+                               htonl((src)->addr)))
+/** IPv4 only: set the IP address given as an u32_t */
+#define ip4_addr_set_u32(dest_ipaddr, src_u32) ((dest_ipaddr)->addr = (src_u32))
+/** IPv4 only: get the IP address as an u32_t */
+#define ip4_addr_get_u32(src_ipaddr) ((src_ipaddr)->addr)
+
+/** Get the network address by combining host address with netmask */
+#define ip_addr_get_network(target, host, netmask) ((target)->addr = ((host)->addr) & ((netmask)->addr))
+
+/**
+ * Determine if two address are on the same network.
+ *
+ * @arg addr1 IP address 1
+ * @arg addr2 IP address 2
+ * @arg mask network identifier mask
+ * @return !0 if the network identifiers of both address match
+ */
+#define ip_addr_netcmp(addr1, addr2, mask) (((addr1)->addr & \
+                                              (mask)->addr) == \
+                                             ((addr2)->addr & \
+                                              (mask)->addr))
+#define ip_addr_cmp(addr1, addr2) ((addr1)->addr == (addr2)->addr)
+
+#define ip_addr_isany(addr1) ((addr1) == NULL || (addr1)->addr == IPADDR_ANY)
+
+#define ip_addr_isbroadcast(ipaddr, netif) ip4_addr_isbroadcast((ipaddr)->addr, (netif))
+u8_t ip4_addr_isbroadcast(u32_t addr, const struct netif *netif);
+
+#define ip_addr_netmask_valid(netmask) ip4_addr_netmask_valid((netmask)->addr)
+u8_t ip4_addr_netmask_valid(u32_t netmask);
+
+#define ip_addr_ismulticast(addr1) (((addr1)->addr & PP_HTONL(0xf0000000UL)) == PP_HTONL(0xe0000000UL))
+
+#define ip_addr_islinklocal(addr1) (((addr1)->addr & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xa9fe0000UL))
+
+#define ip_addr_debug_print(debug, ipaddr) \
+  LWIP_DEBUGF(debug, ("%" U16_F ".%" U16_F ".%" U16_F ".%" U16_F,      \
+                      ipaddr != NULL ? ip4_addr1_16(ipaddr) : 0,       \
+                      ipaddr != NULL ? ip4_addr2_16(ipaddr) : 0,       \
+                      ipaddr != NULL ? ip4_addr3_16(ipaddr) : 0,       \
+                      ipaddr != NULL ? ip4_addr4_16(ipaddr) : 0))
+
+/* Get one byte from the 4-byte address */
+#define ip4_addr1(ipaddr) (((u8_t*)(ipaddr))[0])
+#define ip4_addr2(ipaddr) (((u8_t*)(ipaddr))[1])
+#define ip4_addr3(ipaddr) (((u8_t*)(ipaddr))[2])
+#define ip4_addr4(ipaddr) (((u8_t*)(ipaddr))[3])
+/* These are cast to u16_t, with the intent that they are often arguments
+ * to printf using the U16_F format from cc.h. */
+#define ip4_addr1_16(ipaddr) ((u16_t)ip4_addr1(ipaddr))
+#define ip4_addr2_16(ipaddr) ((u16_t)ip4_addr2(ipaddr))
+#define ip4_addr3_16(ipaddr) ((u16_t)ip4_addr3(ipaddr))
+#define ip4_addr4_16(ipaddr) ((u16_t)ip4_addr4(ipaddr))
+
+#define IP4ADDR_STRLEN_MAX  16
+#define IPADDR_STRLEN_MAX   IP4ADDR_STRLEN_MAX
+
+/** For backwards compatibility */
+#define ip_ntoa(ipaddr)  ipaddr_ntoa(ipaddr)
+
+u32_t ipaddr_addr(const char *cp);
+int ipaddr_aton(const char *cp, ip_addr_t *addr);
+/** returns ptr to static buffer; not reentrant! */
+char *ipaddr_ntoa(const ip_addr_t *addr);
+char *ipaddr_ntoa_r(const ip_addr_t *addr, char *buf, int buflen);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __LWIP_IP_ADDR_H__ */
diff --git a/src/include/ipv6/lwip/ip6_addr.h b/src/include/ipv6/lwip/ip6_addr.h
index 21f6c535..4e5f4a25 100644
--- a/src/include/ipv6/lwip/ip6_addr.h
+++ b/src/include/ipv6/lwip/ip6_addr.h
@@ -1,289 +1,289 @@
-/**
- * @file
- *
- * IPv6 addresses.
- */
-
-/*
- * Copyright (c) 2010 Inico Technologies Ltd.
- * All rights reserved. 
- * 
- * Redistribution and use in source and binary forms, with or without modification, 
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission. 
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
- * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
- * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
- * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
- * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
- * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
- * OF SUCH DAMAGE.
- *
- * This file is part of the lwIP TCP/IP stack.
- * 
- * Author: Ivan Delamer <delamer@inicotech.com>
- *
- * Structs and macros for handling IPv6 addresses.
- *
- * Please coordinate changes and requests with Ivan Delamer
- * <delamer@inicotech.com>
- */
-#ifndef __LWIP_IP6_ADDR_H__
-#define __LWIP_IP6_ADDR_H__
-
-#include "lwip/opt.h"
-
-#if LWIP_IPV6  /* don't build if not configured for use in lwipopts.h */
-
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-
-/* This is the aligned version of ip6_addr_t,
-   used as local variable, on the stack, etc. */
-struct ip6_addr {
-  u32_t addr[4];
-};
-
-/* This is the packed version of ip6_addr_t,
-   used in network headers that are itself packed */
-#ifdef PACK_STRUCT_USE_INCLUDES
-#  include "arch/bpstruct.h"
-#endif
-PACK_STRUCT_BEGIN
-struct ip6_addr_packed {
-  PACK_STRUCT_FIELD(u32_t addr[4]);
-} PACK_STRUCT_STRUCT;
-PACK_STRUCT_END
-#ifdef PACK_STRUCT_USE_INCLUDES
-#  include "arch/epstruct.h"
-#endif
-
-/** ip6_addr_t uses a struct for convenience only, so that the same defines can
- * operate both on ip6_addr_t as well as on ip6_addr_p_t. */
-typedef struct ip6_addr ip6_addr_t;
-typedef struct ip6_addr_packed ip6_addr_p_t;
-
-
-/** IP6_ADDR_ANY can be used as a fixed IPv6 address
- *  for the wildcard
- */
-extern const ip6_addr_t ip6_addr_any;
-#define IP6_ADDR_ANY         ((ip6_addr_t *)&ip6_addr_any)
-
-
-#if BYTE_ORDER == BIG_ENDIAN
-/** Set an IPv6 partial address given by byte-parts. */
-#define IP6_ADDR(ip6addr, index, a,b,c,d) \
-  (ip6addr)->addr[index] = ((u32_t)((a) & 0xff) << 24) | \
-                           ((u32_t)((b) & 0xff) << 16) | \
-                           ((u32_t)((c) & 0xff) << 8)  | \
-                            (u32_t)((d) & 0xff)
-#else
-/** Set an IPv6 partial address given by byte-parts.
-Little-endian version, stored in network order (no htonl). */
-#define IP6_ADDR(ip6addr, index, a,b,c,d) \
-  (ip6addr)->addr[index] = ((u32_t)((d) & 0xff) << 24) | \
-                           ((u32_t)((c) & 0xff) << 16) | \
-                           ((u32_t)((b) & 0xff) << 8)  | \
-                            (u32_t)((a) & 0xff)
-#endif
-
-/** Access address in 16-bit block */
-#define IP6_ADDR_BLOCK1(ip6addr) ((u16_t)(htonl((ip6addr)->addr[0]) >> 16) & 0xffff)
-#define IP6_ADDR_BLOCK2(ip6addr) ((u16_t)(htonl((ip6addr)->addr[0])) & 0xffff)
-#define IP6_ADDR_BLOCK3(ip6addr) ((u16_t)(htonl((ip6addr)->addr[1]) >> 16) & 0xffff)
-#define IP6_ADDR_BLOCK4(ip6addr) ((u16_t)(htonl((ip6addr)->addr[1])) & 0xffff)
-#define IP6_ADDR_BLOCK5(ip6addr) ((u16_t)(htonl((ip6addr)->addr[2]) >> 16) & 0xffff)
-#define IP6_ADDR_BLOCK6(ip6addr) ((u16_t)(htonl((ip6addr)->addr[2])) & 0xffff)
-#define IP6_ADDR_BLOCK7(ip6addr) ((u16_t)(htonl((ip6addr)->addr[3]) >> 16) & 0xffff)
-#define IP6_ADDR_BLOCK8(ip6addr) ((u16_t)(htonl((ip6addr)->addr[3])) & 0xffff)
-
-/** Copy IPv6 address - faster than ip6_addr_set: no NULL check */
-#define ip6_addr_copy(dest, src) do{(dest).addr[0] = (src).addr[0]; \
-                                    (dest).addr[1] = (src).addr[1]; \
-                                    (dest).addr[2] = (src).addr[2]; \
-                                    (dest).addr[3] = (src).addr[3];}while(0)
-/** Safely copy one IPv6 address to another (src may be NULL) */
-#define ip6_addr_set(dest, src) do{(dest)->addr[0] = (src) == NULL ? 0 : (src)->addr[0]; \
-                                   (dest)->addr[1] = (src) == NULL ? 0 : (src)->addr[1]; \
-                                   (dest)->addr[2] = (src) == NULL ? 0 : (src)->addr[2]; \
-                                   (dest)->addr[3] = (src) == NULL ? 0 : (src)->addr[3];}while(0)
-
-/** Set complete address to zero */
-#define ip6_addr_set_zero(ip6addr)    do{(ip6addr)->addr[0] = 0; \
-                                         (ip6addr)->addr[1] = 0; \
-                                         (ip6addr)->addr[2] = 0; \
-                                         (ip6addr)->addr[3] = 0;}while(0)
-
-/** Set address to ipv6 'any' (no need for htonl()) */
-#define ip6_addr_set_any(ip6addr)       ip6_addr_set_zero(ip6addr)
-/** Set address to ipv6 loopback address */
-#define ip6_addr_set_loopback(ip6addr) do{(ip6addr)->addr[0] = 0; \
-                                          (ip6addr)->addr[1] = 0; \
-                                          (ip6addr)->addr[2] = 0; \
-                                          (ip6addr)->addr[3] = PP_HTONL(0x00000001UL);}while(0)
-/** Safely copy one IPv6 address to another and change byte order
- * from host- to network-order. */
-#define ip6_addr_set_hton(dest, src) do{(dest)->addr[0] = (src) == NULL ? 0 : htonl((src)->addr[0]); \
-                                        (dest)->addr[1] = (src) == NULL ? 0 : htonl((src)->addr[1]); \
-                                        (dest)->addr[2] = (src) == NULL ? 0 : htonl((src)->addr[2]); \
-                                        (dest)->addr[3] = (src) == NULL ? 0 : htonl((src)->addr[3]);}while(0)
-
-
-/**
- * Determine if two IPv6 address are on the same network.
- *
- * @arg addr1 IPv6 address 1
- * @arg addr2 IPv6 address 2
- * @return !0 if the network identifiers of both address match
- */
-#define ip6_addr_netcmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
-                                       ((addr1)->addr[1] == (addr2)->addr[1]))
-
-#define ip6_addr_cmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
-                                    ((addr1)->addr[1] == (addr2)->addr[1]) && \
-                                    ((addr1)->addr[2] == (addr2)->addr[2]) && \
-                                    ((addr1)->addr[3] == (addr2)->addr[3]))
-
-#define ip6_get_subnet_id(ip6addr)   (htonl((ip6addr)->addr[2]) & 0x0000ffffUL)
-
-#define ip6_addr_isany(ip6addr) (((ip6addr) == NULL) || \
-                             (((ip6addr)->addr[0] == 0) && \
-                             ((ip6addr)->addr[1] == 0) && \
-                             ((ip6addr)->addr[2] == 0) && \
-                             ((ip6addr)->addr[3] == 0)))
-
-#define ip6_addr_isloopback(ip6addr) (((ip6addr)->addr[0] == 0UL) && \
-                                      ((ip6addr)->addr[1] == 0UL) && \
-                                      ((ip6addr)->addr[2] == 0UL) && \
-                                      ((ip6addr)->addr[3] == PP_HTONL(0x00000001UL)))
-
-#define ip6_addr_isglobal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xe0000000UL)) == PP_HTONL(0x20000000UL))
-
-#define ip6_addr_islinklocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffc00000UL)) == PP_HTONL(0xfe800000UL))
-
-#define ip6_addr_issitelocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffc00000UL)) == PP_HTONL(0xfec00000UL))
-
-#define ip6_addr_isuniquelocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xfe000000UL)) == PP_HTONL(0xfc000000UL))
-
-#define ip6_addr_ismulticast(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xff000000UL)) == PP_HTONL(0xff000000UL))
-#define ip6_addr_multicast_transient_flag(ip6addr)  ((ip6addr)->addr[0] & PP_HTONL(0x00100000UL))
-#define ip6_addr_multicast_prefix_flag(ip6addr)     ((ip6addr)->addr[0] & PP_HTONL(0x00200000UL))
-#define ip6_addr_multicast_rendezvous_flag(ip6addr) ((ip6addr)->addr[0] & PP_HTONL(0x00400000UL))
-#define ip6_addr_multicast_scope(ip6addr) ((htonl((ip6addr)->addr[0]) >> 16) & 0xf)
-#define IP6_MULTICAST_SCOPE_RESERVED            0x0
-#define IP6_MULTICAST_SCOPE_RESERVED0           0x0
-#define IP6_MULTICAST_SCOPE_INTERFACE_LOCAL     0x1
-#define IP6_MULTICAST_SCOPE_LINK_LOCAL          0x2
-#define IP6_MULTICAST_SCOPE_RESERVED3           0x3
-#define IP6_MULTICAST_SCOPE_ADMIN_LOCAL         0x4
-#define IP6_MULTICAST_SCOPE_SITE_LOCAL          0x5
-#define IP6_MULTICAST_SCOPE_ORGANIZATION_LOCAL  0x8
-#define IP6_MULTICAST_SCOPE_GLOBAL              0xe
-#define IP6_MULTICAST_SCOPE_RESERVEDF           0xf
-#define ip6_addr_ismulticast_iflocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff010000UL))
-#define ip6_addr_ismulticast_linklocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff020000UL))
-#define ip6_addr_ismulticast_adminlocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff040000UL))
-#define ip6_addr_ismulticast_sitelocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff050000UL))
-#define ip6_addr_ismulticast_orglocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff080000UL))
-#define ip6_addr_ismulticast_global(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff0e0000UL))
-
-/* TODO define get/set for well-know multicast addresses, e.g. ff02::1 */
-#define ip6_addr_isallnodes_iflocal(ip6addr) (((ip6addr)->addr[0] == PP_HTONL(0xff010000UL)) && \
-    ((ip6addr)->addr[1] == 0UL) && \
-    ((ip6addr)->addr[2] == 0UL) && \
-    ((ip6addr)->addr[3] == PP_HTONL(0x00000001UL)))
-
-#define ip6_addr_isallnodes_linklocal(ip6addr) (((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
-    ((ip6addr)->addr[1] == 0UL) && \
-    ((ip6addr)->addr[2] == 0UL) && \
-    ((ip6addr)->addr[3] == PP_HTONL(0x00000001UL)))
-#define ip6_addr_set_allnodes_linklocal(ip6addr) do{(ip6addr)->addr[0] = PP_HTONL(0xff020000UL); \
-                (ip6addr)->addr[1] = 0; \
-                (ip6addr)->addr[2] = 0; \
-                (ip6addr)->addr[3] = PP_HTONL(0x00000001UL);}while(0)
-
-#define ip6_addr_isallrouters_linklocal(ip6addr) (((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
-    ((ip6addr)->addr[1] == 0UL) && \
-    ((ip6addr)->addr[2] == 0UL) && \
-    ((ip6addr)->addr[3] == PP_HTONL(0x00000002UL)))
-#define ip6_addr_set_allrouters_linklocal(ip6addr) do{(ip6addr)->addr[0] = PP_HTONL(0xff020000UL); \
-                (ip6addr)->addr[1] = 0; \
-                (ip6addr)->addr[2] = 0; \
-                (ip6addr)->addr[3] = PP_HTONL(0x00000002UL);}while(0)
-
-#define ip6_addr_issolicitednode(ip6addr) ( ((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
-        ((ip6addr)->addr[2] == PP_HTONL(0x00000001UL)) && \
-        (((ip6addr)->addr[3] & PP_HTONL(0xff000000UL)) == PP_HTONL(0xff000000UL)) )
-
-#define ip6_addr_set_solicitednode(ip6addr, if_id) do{(ip6addr)->addr[0] = PP_HTONL(0xff020000UL); \
-                (ip6addr)->addr[1] = 0; \
-                (ip6addr)->addr[2] = PP_HTONL(0x00000001UL); \
-                (ip6addr)->addr[3] = (PP_HTONL(0xff000000UL) | (if_id));}while(0)
-
-#define ip6_addr_cmp_solicitednode(ip6addr, sn_addr) (((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
-                                    ((ip6addr)->addr[1] == 0) && \
-                                    ((ip6addr)->addr[2] == PP_HTONL(0x00000001UL)) && \
-                                    ((ip6addr)->addr[3] == (PP_HTONL(0xff000000UL) | (sn_addr)->addr[3])))
-
-/* IPv6 address states. */
-#define IP6_ADDR_INVALID      0x00
-#define IP6_ADDR_TENTATIVE    0x08
-#define IP6_ADDR_TENTATIVE_1  0x09 /* 1 probe sent */
-#define IP6_ADDR_TENTATIVE_2  0x0a /* 2 probes sent */
-#define IP6_ADDR_TENTATIVE_3  0x0b /* 3 probes sent */
-#define IP6_ADDR_TENTATIVE_4  0x0c /* 4 probes sent */
-#define IP6_ADDR_TENTATIVE_5  0x0d /* 5 probes sent */
-#define IP6_ADDR_TENTATIVE_6  0x0e /* 6 probes sent */
-#define IP6_ADDR_TENTATIVE_7  0x0f /* 7 probes sent */
-#define IP6_ADDR_VALID        0x10
-#define IP6_ADDR_PREFERRED    0x30
-#define IP6_ADDR_DEPRECATED   0x50
-
-#define ip6_addr_isinvalid(addr_state) (addr_state == IP6_ADDR_INVALID)
-#define ip6_addr_istentative(addr_state) (addr_state & IP6_ADDR_TENTATIVE)
-#define ip6_addr_isvalid(addr_state) (addr_state & IP6_ADDR_VALID) /* Include valid, preferred, and deprecated. */
-#define ip6_addr_ispreferred(addr_state) (addr_state == IP6_ADDR_PREFERRED)
-#define ip6_addr_isdeprecated(addr_state) (addr_state == IP6_ADDR_DEPRECATED)
-
-#define ip6_addr_debug_print(debug, ipaddr) \
-  LWIP_DEBUGF(debug, ("%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F, \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK1(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK2(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK3(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK4(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK5(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK6(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK7(ipaddr) : 0,    \
-                      ipaddr != NULL ? IP6_ADDR_BLOCK8(ipaddr) : 0))
-
-#define IP6ADDR_STRLEN_MAX    46
-
-int ip6addr_aton(const char *cp, ip6_addr_t *addr);
-/** returns ptr to static buffer; not reentrant! */
-char *ip6addr_ntoa(const ip6_addr_t *addr);
-char *ip6addr_ntoa_r(const ip6_addr_t *addr, char *buf, int buflen);
-
-
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* LWIP_IPV6 */
-
-#endif /* __LWIP_IP6_ADDR_H__ */
+/**
+ * @file
+ *
+ * IPv6 addresses.
+ */
+
+/*
+ * Copyright (c) 2010 Inico Technologies Ltd.
+ * All rights reserved. 
+ * 
+ * Redistribution and use in source and binary forms, with or without modification, 
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ * 
+ * Author: Ivan Delamer <delamer@inicotech.com>
+ *
+ * Structs and macros for handling IPv6 addresses.
+ *
+ * Please coordinate changes and requests with Ivan Delamer
+ * <delamer@inicotech.com>
+ */
+#ifndef __LWIP_IP6_ADDR_H__
+#define __LWIP_IP6_ADDR_H__
+
+#include "lwip/opt.h"
+
+#if LWIP_IPV6  /* don't build if not configured for use in lwipopts.h */
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* This is the aligned version of ip6_addr_t,
+   used as local variable, on the stack, etc. */
+struct ip6_addr {
+  u32_t addr[4];
+};
+
+/* This is the packed version of ip6_addr_t,
+   used in network headers that are itself packed */
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/bpstruct.h"
+#endif
+PACK_STRUCT_BEGIN
+struct ip6_addr_packed {
+  PACK_STRUCT_FIELD(u32_t addr[4]);
+} PACK_STRUCT_STRUCT;
+PACK_STRUCT_END
+#ifdef PACK_STRUCT_USE_INCLUDES
+#  include "arch/epstruct.h"
+#endif
+
+/** ip6_addr_t uses a struct for convenience only, so that the same defines can
+ * operate both on ip6_addr_t as well as on ip6_addr_p_t. */
+typedef struct ip6_addr ip6_addr_t;
+typedef struct ip6_addr_packed ip6_addr_p_t;
+
+
+/** IP6_ADDR_ANY can be used as a fixed IPv6 address
+ *  for the wildcard
+ */
+extern const ip6_addr_t ip6_addr_any;
+#define IP6_ADDR_ANY         ((ip6_addr_t *)&ip6_addr_any)
+
+
+#if BYTE_ORDER == BIG_ENDIAN
+/** Set an IPv6 partial address given by byte-parts. */
+#define IP6_ADDR(ip6addr, index, a,b,c,d) \
+  (ip6addr)->addr[index] = ((u32_t)((a) & 0xff) << 24) | \
+                           ((u32_t)((b) & 0xff) << 16) | \
+                           ((u32_t)((c) & 0xff) << 8)  | \
+                            (u32_t)((d) & 0xff)
+#else
+/** Set an IPv6 partial address given by byte-parts.
+Little-endian version, stored in network order (no htonl). */
+#define IP6_ADDR(ip6addr, index, a,b,c,d) \
+  (ip6addr)->addr[index] = ((u32_t)((d) & 0xff) << 24) | \
+                           ((u32_t)((c) & 0xff) << 16) | \
+                           ((u32_t)((b) & 0xff) << 8)  | \
+                            (u32_t)((a) & 0xff)
+#endif
+
+/** Access address in 16-bit block */
+#define IP6_ADDR_BLOCK1(ip6addr) ((u16_t)(htonl((ip6addr)->addr[0]) >> 16) & 0xffff)
+#define IP6_ADDR_BLOCK2(ip6addr) ((u16_t)(htonl((ip6addr)->addr[0])) & 0xffff)
+#define IP6_ADDR_BLOCK3(ip6addr) ((u16_t)(htonl((ip6addr)->addr[1]) >> 16) & 0xffff)
+#define IP6_ADDR_BLOCK4(ip6addr) ((u16_t)(htonl((ip6addr)->addr[1])) & 0xffff)
+#define IP6_ADDR_BLOCK5(ip6addr) ((u16_t)(htonl((ip6addr)->addr[2]) >> 16) & 0xffff)
+#define IP6_ADDR_BLOCK6(ip6addr) ((u16_t)(htonl((ip6addr)->addr[2])) & 0xffff)
+#define IP6_ADDR_BLOCK7(ip6addr) ((u16_t)(htonl((ip6addr)->addr[3]) >> 16) & 0xffff)
+#define IP6_ADDR_BLOCK8(ip6addr) ((u16_t)(htonl((ip6addr)->addr[3])) & 0xffff)
+
+/** Copy IPv6 address - faster than ip6_addr_set: no NULL check */
+#define ip6_addr_copy(dest, src) do{(dest).addr[0] = (src).addr[0]; \
+                                    (dest).addr[1] = (src).addr[1]; \
+                                    (dest).addr[2] = (src).addr[2]; \
+                                    (dest).addr[3] = (src).addr[3];}while(0)
+/** Safely copy one IPv6 address to another (src may be NULL) */
+#define ip6_addr_set(dest, src) do{(dest)->addr[0] = (src) == NULL ? 0 : (src)->addr[0]; \
+                                   (dest)->addr[1] = (src) == NULL ? 0 : (src)->addr[1]; \
+                                   (dest)->addr[2] = (src) == NULL ? 0 : (src)->addr[2]; \
+                                   (dest)->addr[3] = (src) == NULL ? 0 : (src)->addr[3];}while(0)
+
+/** Set complete address to zero */
+#define ip6_addr_set_zero(ip6addr)    do{(ip6addr)->addr[0] = 0; \
+                                         (ip6addr)->addr[1] = 0; \
+                                         (ip6addr)->addr[2] = 0; \
+                                         (ip6addr)->addr[3] = 0;}while(0)
+
+/** Set address to ipv6 'any' (no need for htonl()) */
+#define ip6_addr_set_any(ip6addr)       ip6_addr_set_zero(ip6addr)
+/** Set address to ipv6 loopback address */
+#define ip6_addr_set_loopback(ip6addr) do{(ip6addr)->addr[0] = 0; \
+                                          (ip6addr)->addr[1] = 0; \
+                                          (ip6addr)->addr[2] = 0; \
+                                          (ip6addr)->addr[3] = PP_HTONL(0x00000001UL);}while(0)
+/** Safely copy one IPv6 address to another and change byte order
+ * from host- to network-order. */
+#define ip6_addr_set_hton(dest, src) do{(dest)->addr[0] = (src) == NULL ? 0 : htonl((src)->addr[0]); \
+                                        (dest)->addr[1] = (src) == NULL ? 0 : htonl((src)->addr[1]); \
+                                        (dest)->addr[2] = (src) == NULL ? 0 : htonl((src)->addr[2]); \
+                                        (dest)->addr[3] = (src) == NULL ? 0 : htonl((src)->addr[3]);}while(0)
+
+
+/**
+ * Determine if two IPv6 address are on the same network.
+ *
+ * @arg addr1 IPv6 address 1
+ * @arg addr2 IPv6 address 2
+ * @return !0 if the network identifiers of both address match
+ */
+#define ip6_addr_netcmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
+                                       ((addr1)->addr[1] == (addr2)->addr[1]))
+
+#define ip6_addr_cmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
+                                    ((addr1)->addr[1] == (addr2)->addr[1]) && \
+                                    ((addr1)->addr[2] == (addr2)->addr[2]) && \
+                                    ((addr1)->addr[3] == (addr2)->addr[3]))
+
+#define ip6_get_subnet_id(ip6addr)   (htonl((ip6addr)->addr[2]) & 0x0000ffffUL)
+
+#define ip6_addr_isany(ip6addr) (((ip6addr) == NULL) || \
+                             (((ip6addr)->addr[0] == 0) && \
+                             ((ip6addr)->addr[1] == 0) && \
+                             ((ip6addr)->addr[2] == 0) && \
+                             ((ip6addr)->addr[3] == 0)))
+
+#define ip6_addr_isloopback(ip6addr) (((ip6addr)->addr[0] == 0UL) && \
+                                      ((ip6addr)->addr[1] == 0UL) && \
+                                      ((ip6addr)->addr[2] == 0UL) && \
+                                      ((ip6addr)->addr[3] == PP_HTONL(0x00000001UL)))
+
+#define ip6_addr_isglobal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xe0000000UL)) == PP_HTONL(0x20000000UL))
+
+#define ip6_addr_islinklocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffc00000UL)) == PP_HTONL(0xfe800000UL))
+
+#define ip6_addr_issitelocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffc00000UL)) == PP_HTONL(0xfec00000UL))
+
+#define ip6_addr_isuniquelocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xfe000000UL)) == PP_HTONL(0xfc000000UL))
+
+#define ip6_addr_ismulticast(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xff000000UL)) == PP_HTONL(0xff000000UL))
+#define ip6_addr_multicast_transient_flag(ip6addr)  ((ip6addr)->addr[0] & PP_HTONL(0x00100000UL))
+#define ip6_addr_multicast_prefix_flag(ip6addr)     ((ip6addr)->addr[0] & PP_HTONL(0x00200000UL))
+#define ip6_addr_multicast_rendezvous_flag(ip6addr) ((ip6addr)->addr[0] & PP_HTONL(0x00400000UL))
+#define ip6_addr_multicast_scope(ip6addr) ((htonl((ip6addr)->addr[0]) >> 16) & 0xf)
+#define IP6_MULTICAST_SCOPE_RESERVED            0x0
+#define IP6_MULTICAST_SCOPE_RESERVED0           0x0
+#define IP6_MULTICAST_SCOPE_INTERFACE_LOCAL     0x1
+#define IP6_MULTICAST_SCOPE_LINK_LOCAL          0x2
+#define IP6_MULTICAST_SCOPE_RESERVED3           0x3
+#define IP6_MULTICAST_SCOPE_ADMIN_LOCAL         0x4
+#define IP6_MULTICAST_SCOPE_SITE_LOCAL          0x5
+#define IP6_MULTICAST_SCOPE_ORGANIZATION_LOCAL  0x8
+#define IP6_MULTICAST_SCOPE_GLOBAL              0xe
+#define IP6_MULTICAST_SCOPE_RESERVEDF           0xf
+#define ip6_addr_ismulticast_iflocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff010000UL))
+#define ip6_addr_ismulticast_linklocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff020000UL))
+#define ip6_addr_ismulticast_adminlocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff040000UL))
+#define ip6_addr_ismulticast_sitelocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff050000UL))
+#define ip6_addr_ismulticast_orglocal(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff080000UL))
+#define ip6_addr_ismulticast_global(ip6addr) (((ip6addr)->addr[0] & PP_HTONL(0xffff0000UL)) == PP_HTONL(0xff0e0000UL))
+
+/* TODO define get/set for well-know multicast addresses, e.g. ff02::1 */
+#define ip6_addr_isallnodes_iflocal(ip6addr) (((ip6addr)->addr[0] == PP_HTONL(0xff010000UL)) && \
+    ((ip6addr)->addr[1] == 0UL) && \
+    ((ip6addr)->addr[2] == 0UL) && \
+    ((ip6addr)->addr[3] == PP_HTONL(0x00000001UL)))
+
+#define ip6_addr_isallnodes_linklocal(ip6addr) (((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
+    ((ip6addr)->addr[1] == 0UL) && \
+    ((ip6addr)->addr[2] == 0UL) && \
+    ((ip6addr)->addr[3] == PP_HTONL(0x00000001UL)))
+#define ip6_addr_set_allnodes_linklocal(ip6addr) do{(ip6addr)->addr[0] = PP_HTONL(0xff020000UL); \
+                (ip6addr)->addr[1] = 0; \
+                (ip6addr)->addr[2] = 0; \
+                (ip6addr)->addr[3] = PP_HTONL(0x00000001UL);}while(0)
+
+#define ip6_addr_isallrouters_linklocal(ip6addr) (((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
+    ((ip6addr)->addr[1] == 0UL) && \
+    ((ip6addr)->addr[2] == 0UL) && \
+    ((ip6addr)->addr[3] == PP_HTONL(0x00000002UL)))
+#define ip6_addr_set_allrouters_linklocal(ip6addr) do{(ip6addr)->addr[0] = PP_HTONL(0xff020000UL); \
+                (ip6addr)->addr[1] = 0; \
+                (ip6addr)->addr[2] = 0; \
+                (ip6addr)->addr[3] = PP_HTONL(0x00000002UL);}while(0)
+
+#define ip6_addr_issolicitednode(ip6addr) ( ((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
+        ((ip6addr)->addr[2] == PP_HTONL(0x00000001UL)) && \
+        (((ip6addr)->addr[3] & PP_HTONL(0xff000000UL)) == PP_HTONL(0xff000000UL)) )
+
+#define ip6_addr_set_solicitednode(ip6addr, if_id) do{(ip6addr)->addr[0] = PP_HTONL(0xff020000UL); \
+                (ip6addr)->addr[1] = 0; \
+                (ip6addr)->addr[2] = PP_HTONL(0x00000001UL); \
+                (ip6addr)->addr[3] = (PP_HTONL(0xff000000UL) | (if_id));}while(0)
+
+#define ip6_addr_cmp_solicitednode(ip6addr, sn_addr) (((ip6addr)->addr[0] == PP_HTONL(0xff020000UL)) && \
+                                    ((ip6addr)->addr[1] == 0) && \
+                                    ((ip6addr)->addr[2] == PP_HTONL(0x00000001UL)) && \
+                                    ((ip6addr)->addr[3] == (PP_HTONL(0xff000000UL) | (sn_addr)->addr[3])))
+
+/* IPv6 address states. */
+#define IP6_ADDR_INVALID      0x00
+#define IP6_ADDR_TENTATIVE    0x08
+#define IP6_ADDR_TENTATIVE_1  0x09 /* 1 probe sent */
+#define IP6_ADDR_TENTATIVE_2  0x0a /* 2 probes sent */
+#define IP6_ADDR_TENTATIVE_3  0x0b /* 3 probes sent */
+#define IP6_ADDR_TENTATIVE_4  0x0c /* 4 probes sent */
+#define IP6_ADDR_TENTATIVE_5  0x0d /* 5 probes sent */
+#define IP6_ADDR_TENTATIVE_6  0x0e /* 6 probes sent */
+#define IP6_ADDR_TENTATIVE_7  0x0f /* 7 probes sent */
+#define IP6_ADDR_VALID        0x10
+#define IP6_ADDR_PREFERRED    0x30
+#define IP6_ADDR_DEPRECATED   0x50
+
+#define ip6_addr_isinvalid(addr_state) (addr_state == IP6_ADDR_INVALID)
+#define ip6_addr_istentative(addr_state) (addr_state & IP6_ADDR_TENTATIVE)
+#define ip6_addr_isvalid(addr_state) (addr_state & IP6_ADDR_VALID) /* Include valid, preferred, and deprecated. */
+#define ip6_addr_ispreferred(addr_state) (addr_state == IP6_ADDR_PREFERRED)
+#define ip6_addr_isdeprecated(addr_state) (addr_state == IP6_ADDR_DEPRECATED)
+
+#define ip6_addr_debug_print(debug, ipaddr) \
+  LWIP_DEBUGF(debug, ("%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F ":%" X16_F, \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK1(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK2(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK3(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK4(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK5(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK6(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK7(ipaddr) : 0,    \
+                      ipaddr != NULL ? IP6_ADDR_BLOCK8(ipaddr) : 0))
+
+#define IP6ADDR_STRLEN_MAX    46
+
+int ip6addr_aton(const char *cp, ip6_addr_t *addr);
+/** returns ptr to static buffer; not reentrant! */
+char *ip6addr_ntoa(const ip6_addr_t *addr);
+char *ip6addr_ntoa_r(const ip6_addr_t *addr, char *buf, int buflen);
+
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* LWIP_IPV6 */
+
+#endif /* __LWIP_IP6_ADDR_H__ */