From 7721b20179dad3ae9c51bbcabc4dbb3ad82b6ff5 Mon Sep 17 00:00:00 2001
From: sg <goldsimon@gmx.de>
Date: Wed, 23 Mar 2016 21:57:38 +0100
Subject: [PATCH] call accept-callback with ERR_MEM when allocating a pcb fails
 on passive open to inform the application about this error; ATTENTION:
 applications have to handle NULL pcb in accept callback!

---
 CHANGELOG                        |  5 +++++
 src/api/api_msg.c                |  8 ++++++++
 src/apps/httpd/httpd.c           |  4 ++++
 src/core/tcp_in.c                |  4 +++-
 src/include/lwip/priv/tcp_priv.h | 12 ++++++------
 5 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 24fd8f00..962850af 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -6,6 +6,11 @@ HISTORY
 
   ++ New features:
 
+  2016-03-23: Simon Goldschmidt
+  * tcp: call accept-callback with ERR_MEM when allocating a pcb fails on
+    passive open to inform the application about this error
+	ATTENTION: applications have to handle NULL pcb in accept callback!
+
   2016-02-22: Ivan Delamer
   * Initial 6LoWPAN support
 
diff --git a/src/api/api_msg.c b/src/api/api_msg.c
index 6a1060b3..96a4023c 100644
--- a/src/api/api_msg.c
+++ b/src/api/api_msg.c
@@ -468,6 +468,14 @@ accept_function(void *arg, struct tcp_pcb *newpcb, err_t err)
 
   LWIP_DEBUGF(API_MSG_DEBUG, ("accept_function: newpcb->tate: %s\n", tcp_debug_state_str(newpcb->state)));
 
+  if ((err != ERR_OK) || (arg == NULL)) {
+    return ERR_VAL;
+  }
+  if (newpcb == NULL) {
+    /* @todo: out-of-pcbs during connect: pass on this error to the application */
+    return ERR_VAL;
+  }
+
   if (!sys_mbox_valid(&conn->acceptmbox)) {
     LWIP_DEBUGF(API_MSG_DEBUG, ("accept_function: acceptmbox already deleted\n"));
     return ERR_VAL;
diff --git a/src/apps/httpd/httpd.c b/src/apps/httpd/httpd.c
index 97c393e2..832dd18f 100644
--- a/src/apps/httpd/httpd.c
+++ b/src/apps/httpd/httpd.c
@@ -2290,6 +2290,10 @@ http_accept(void *arg, struct tcp_pcb *pcb, err_t err)
   LWIP_UNUSED_ARG(err);
   LWIP_DEBUGF(HTTPD_DEBUG, ("http_accept %p / %p\n", (void*)pcb, arg));
 
+  if ((err != ERR_OK) || (pcb == NULL)) {
+    return ERR_VAL;
+  }
+
   /* Set priority */
   tcp_setprio(pcb, HTTPD_TCP_PRIO);
 
diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index 3d5cfa0f..be935ccc 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -562,8 +562,10 @@ tcp_listen_input(struct tcp_pcb_listen *pcb)
        we don't do anything, but rely on the sender will retransmit the
        SYN at a time when we have more memory available. */
     if (npcb == NULL) {
+      err_t err;
       LWIP_DEBUGF(TCP_DEBUG, ("tcp_listen_input: could not allocate PCB\n"));
       TCP_STATS_INC(tcp.memerr);
+      TCP_EVENT_ACCEPT(pcb, NULL, pcb->callback_arg, ERR_MEM, err);
       return ERR_MEM;
     }
 #if TCP_LISTEN_BACKLOG
@@ -794,7 +796,7 @@ tcp_process(struct tcp_pcb *pcb)
         {
           tcp_backlog_accepted(pcb);
           /* Call the accept function. */
-          TCP_EVENT_ACCEPT(pcb, ERR_OK, err);
+          TCP_EVENT_ACCEPT(pcb->listener, pcb, pcb->callback_arg, ERR_OK, err);
         }
         if (err != ERR_OK) {
           /* If the accept function returns with an error, we abort
diff --git a/src/include/lwip/priv/tcp_priv.h b/src/include/lwip/priv/tcp_priv.h
index 183cee2b..b14e944e 100644
--- a/src/include/lwip/priv/tcp_priv.h
+++ b/src/include/lwip/priv/tcp_priv.h
@@ -199,7 +199,7 @@ PACK_STRUCT_END
 
 #if LWIP_EVENT_API
 
-#define TCP_EVENT_ACCEPT(pcb,err,ret)    ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
+#define TCP_EVENT_ACCEPT(lpcb,pcb,arg,err,ret) ret = lwip_tcp_event(arg, (pcb),\
                 LWIP_EVENT_ACCEPT, NULL, 0, err)
 #define TCP_EVENT_SENT(pcb,space,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
                    LWIP_EVENT_SENT, NULL, space, ERR_OK)
@@ -216,11 +216,11 @@ PACK_STRUCT_END
 
 #else /* LWIP_EVENT_API */
 
-#define TCP_EVENT_ACCEPT(pcb,err,ret)                                   \
-  do {                                                                  \
-    if(((pcb)->listener != NULL) && ((pcb)->listener->accept != NULL))  \
-      (ret) = (pcb)->listener->accept((pcb)->callback_arg,(pcb),(err)); \
-    else (ret) = ERR_ARG;                                               \
+#define TCP_EVENT_ACCEPT(lpcb,pcb,arg,err,ret)                 \
+  do {                                                         \
+    if((lpcb != NULL) && ((lpcb)->accept != NULL))             \
+      (ret) = (lpcb)->accept((arg),(pcb),(err));               \
+    else (ret) = ERR_ARG;                                      \
   } while (0)
 
 #define TCP_EVENT_SENT(pcb,space,ret)                          \