altcp: simplify creating different types by adding an allocator concept

This is done with an example in the http_client

Signed-off-by: goldsimon <goldsimon@gmx.de>

src/core/altcp.c

@@ -49,6 +49,7 @@
 
 #include "lwip/altcp.h"
 #include "lwip/priv/altcp_priv.h"
+#include "lwip/altcp_tcp.h"
 #include "lwip/tcp.h"
 #include "lwip/mem.h"
 
@@ -56,6 +57,9 @@
 
 extern const struct altcp_functions altcp_tcp_functions;
 
+/** For altcp layer implementations only: allocate a new struct altcp_pcb from the pool
+ * and zero the memory
+ */
 struct altcp_pcb *
 altcp_alloc(void)
 {
@@ -66,6 +70,8 @@ altcp_alloc(void)
   return ret;
 }
 
+/** For altcp layer implementations only: return a struct altcp_pcb to the pool
+ */
 void
 altcp_free(struct altcp_pcb *conn)
 {
@@ -77,6 +83,47 @@ altcp_free(struct altcp_pcb *conn)
   }
 }
 
+/** altcp_new_ip6: @ref altcp_new for IPv6 */
+struct altcp_pcb *
+altcp_new_ip6(altcp_allocator_t *allocator)
+{
+  return altcp_new_ip_type(allocator, IPADDR_TYPE_V6);
+}
+
+/** altcp_new: @ref altcp_new for IPv4 */
+struct altcp_pcb *
+altcp_new(altcp_allocator_t *allocator)
+{
+  return altcp_new_ip_type(allocator, IPADDR_TYPE_V4);
+}
+
+/** altcp_new_ip_type: called by applications to allocate a new pcb with the help of an
+ * allocator function.
+ *
+ * @param allocator allocator function and argument
+ * @param ip_type IP version of the pcb (IPADDR_TYPE_V4/IPADDR_TYPE_V6)
+ * @return a new altcp_pcb or NULL on error
+ */
+struct altcp_pcb *
+altcp_new_ip_type(altcp_allocator_t *allocator, u8_t ip_type)
+{
+  struct altcp_pcb *conn;
+  if (allocator == NULL) {
+    /* no allocator given, create a simple TCP connection */
+    return altcp_tcp_new_ip_type(ip_type);
+  }
+  if (allocator->alloc == NULL) {
+    /* illegal allocator */
+    return NULL;
+  }
+  conn = allocator->alloc(allocator->arg, ip_type);
+  if (conn == NULL) {
+    /* allocation failed */
+    return NULL;
+  }
+  return conn;
+}
+
 /**
  * @ingroup altcp
  * @see tcp_arg()

src/core/altcp_alloc.c

@@ -0,0 +1,81 @@
+/**
+ * @file
+ * Application layered TCP connection API (to be used from TCPIP thread)\n
+ * This interface mimics the tcp callback API to the application while preventing
+ * direct linking (much like virtual functions).
+ * This way, an application can make use of other application layer protocols
+ * on top of TCP without knowing the details (e.g. TLS, proxy connection).
+ *
+ * This file contains allocation implementation that combine several layers.
+ */
+
+/*
+ * Copyright (c) 2017 Simon Goldschmidt
+ * 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: Simon Goldschmidt <goldsimon@gmx.de>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#if LWIP_ALTCP /* don't build if not configured for use in lwipopts.h */
+
+#include "lwip/altcp.h"
+#include "lwip/altcp_tcp.h"
+#include "lwip/altcp_tls.h"
+#include "lwip/priv/altcp_priv.h"
+#include "lwip/mem.h"
+
+#include <string.h>
+
+#if LWIP_ALTCP_TLS
+
+/** This standard allocator function creates an altcp pcb for
+ * TLS over TCP */
+struct altcp_pcb *
+altcp_tls_alloc(void *arg, u8_t ip_type)
+{
+  struct altcp_pcb *inner_conn, *ret;
+  struct altcp_tls_config *config = (struct altcp_tls_config *)arg;
+  LWIP_UNUSED_ARG(ip_type);
+
+  inner_conn = altcp_tcp_new_ip_type(ip_type);
+  if (inner_conn == NULL) {
+    return NULL;
+  }
+  ret = altcp_tls_new(config, inner_conn);
+  if (ret == NULL) {
+    altcp_free(inner_conn);
+  }
+  return ret;
+}
+
+
+#endif /* LWIP_ALTCP_TLS */
+
+#endif /* LWIP_ALTCP */

src/core/altcp_tcp.c

@@ -201,6 +201,17 @@ altcp_tcp_new_ip_type(u8_t ip_type)
   return NULL;
 }
 
+/** altcp_tcp allocator function fitting to @ref altcp_allocator_t / @ref altcp_new.
+*
+* arg pointer is not used for TCP.
+*/
+struct altcp_pcb *
+altcp_tcp_alloc(void *arg, u8_t ip_type)
+{
+  LWIP_UNUSED_ARG(arg);
+  return altcp_tcp_new_ip_type(ip_type);
+}
+
 struct altcp_pcb *
 altcp_tcp_wrap(struct tcp_pcb *tpcb)
 {