Checked in slightly modified version of patch # 6370: Moved loopif code to netif.c so that loopback traffic is supported on all netifs (all local IPs).

src/include/lwip/netif.h

@@ -34,6 +34,8 @@
 
 #include "lwip/opt.h"
 
+#define ENABLE_LOOPBACK (LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF)
+
 #include "lwip/err.h"
 
 #include "lwip/ip_addr.h"
@@ -165,6 +167,11 @@ struct netif {
 #if LWIP_NETIF_HWADDRHINT
   u8_t *addr_hint;
 #endif /* LWIP_NETIF_HWADDRHINT */
+#if ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING
+  /* List of packets to be queued for ourselves. */
+  struct pbuf *loop_first;
+  struct pbuf *loop_last;
+#endif /* ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING */
 };
 
 #if LWIP_SNMP
@@ -242,4 +249,12 @@ void netif_set_link_callback(struct netif *netif, void (* link_callback)(struct
 }
 #endif
 
+#if ENABLE_LOOPBACK
+err_t netif_loop_output(struct netif *netif, struct pbuf *p, struct ip_addr *dest_ip);
+#if !LWIP_NETIF_LOOPBACK_MULTITHREADING
+void netif_poll_all(void);
+void netif_poll(struct netif *netif);
+#endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
+#endif /* ENABLE_LOOPBACK */
+
 #endif /* __LWIP_NETIF_H__ */

src/include/lwip/opt.h

@@ -832,6 +832,31 @@
 #define LWIP_NETIF_HWADDRHINT           0
 #endif
 
+/**
+ * LWIP_NETIF_LOOPBACK==1: Support sending packets with a destination IP
+ * address equal to the netif IP address, looping them back up the stack.
+ */
+#ifndef LWIP_NETIF_LOOPBACK
+#define LWIP_NETIF_LOOPBACK             0
+#endif
+
+/**
+ * LWIP_NETIF_LOOPBACK_MULTITHREADING: Indicates whether threading is enabled in
+ * the system, as netifs must change how they behave depending on this setting
+ * for the LWIP_NETIF_LOOPBACK option to work.
+ * Setting this is needed to avoid reentering non-reentrant functions like
+ * tcp_input().
+ *    LWIP_NETIF_LOOPBACK_MULTITHREADING==1: Indicates that the user is using a
+ *       multithreaded environment like tcpip.c. In this case, netif->input()
+ *       is called directly.
+ *    LWIP_NETIF_LOOPBACK_MULTITHREADING==0: Indicates a polling (or NO_SYS) setup.
+ *       The packets are put on a list and netif_poll() must be called in
+ *       the main application loop.
+ */
+#ifndef LWIP_NETIF_LOOPBACK_MULTITHREADING
+#define LWIP_NETIF_LOOPBACK_MULTITHREADING    (!NO_SYS)
+#endif
+
 /*
    ------------------------------------
    ---------- LOOPIF options ----------
@@ -844,22 +869,6 @@
 #define LWIP_HAVE_LOOPIF                0
 #endif
 
-/**
- * LWIP_LOOPIF_MULTITHREADING: Indicates whether threading is enabled in
- * the system, as LOOPIF must change how it behaves depending on this setting.
- * Setting this is needed to avoid reentering non-reentrant functions like
- * tcp_input().
- *    LWIP_LOOPIF_MULTITHREADING==1: Indicates that the user is using a
- *       multithreaded environment like tcpip.c. In this case, netif->input()
- *       is called directly.
- *    LWIP_LOOPIF_MULTITHREADING==0: Indicates a polling (or NO_SYS) setup.
- *       The packets are put on a list and loopif_poll() must be called in
- *       the main application loop.
- */
-#ifndef LWIP_LOOPIF_MULTITHREADING
-#define LWIP_LOOPIF_MULTITHREADING      1
-#endif
-
 /*
    ------------------------------------
    ---------- Thread options ----------

src/include/netif/loopif.h

@@ -39,8 +39,8 @@
 extern "C" {
 #endif
 
-#if !LWIP_LOOPIF_MULTITHREADING
-void loopif_poll(struct netif *netif);
+#if !LWIP_NETIF_LOOPBACK_MULTITHREADING
+#define loopif_poll(netif) netif_poll()
 #endif
 
 err_t loopif_init(struct netif *netif);