BUG25622: handle return code of tcp_enqueue in tcp_listen_input()

CHANGELOG

@@ -76,7 +76,11 @@ HISTORY
   ++ Bugfixes:
 
   2009-03-26 Kieran Mansley
-  * tcp_out.c: set TCP_ACK flag on keepalive and zero window probes
+  * tcp.c, tcp_in.c, tcp.h: add tcp_abandon() to cope with dropping
+    connections where no reset required (bug #25622)
+
+  * tcp_out.c: set TCP_ACK flag on keepalive and zero window probes 
+    (bug #20779)
 
   2009-02-18 Simon Goldschmidt (Jonathan Larmour and Bill Auerbach)
   * ip_frag.c: patch #6528: the buffer used for IP_FRAG_USES_STATIC_BUF could be

src/core/tcp.c

@@ -186,14 +186,15 @@ tcp_close(struct tcp_pcb *pcb)
 }
 
 /**
- * Aborts a connection by sending a RST to the remote host and deletes
- * the local protocol control block. This is done when a connection is
- * killed because of shortage of memory.
+ * Abandons a connection and optionally sends a RST to the remote
+ * host.  Deletes the local protocol control block. This is done when
+ * a connection is killed because of shortage of memory.
  *
  * @param pcb the tcp_pcb to abort
+ * @param reset boolean to indicate whether a reset should be sent
  */
 void
-tcp_abort(struct tcp_pcb *pcb)
+tcp_abandon(struct tcp_pcb *pcb, int reset)
 {
   u32_t seqno, ackno;
   u16_t remote_port, local_port;
@@ -235,8 +236,10 @@ tcp_abort(struct tcp_pcb *pcb)
 #endif /* TCP_QUEUE_OOSEQ */
     memp_free(MEMP_TCP_PCB, pcb);
     TCP_EVENT_ERR(errf, errf_arg, ERR_ABRT);
-    LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_abort: sending RST\n"));
-    tcp_rst(seqno, ackno, &local_ip, &remote_ip, local_port, remote_port);
+    if (reset) {
+      LWIP_DEBUGF(TCP_RST_DEBUG, ("tcp_abandon: sending RST\n"));
+      tcp_rst(seqno, ackno, &local_ip, &remote_ip, local_port, remote_port);
+    }
   }
 }
 

src/core/tcp_in.c

@@ -394,6 +394,7 @@ tcp_listen_input(struct tcp_pcb_listen *pcb)
 {
   struct tcp_pcb *npcb;
   u32_t optdata;
+  err_t rc;
 
   /* In the LISTEN state, we check for incoming SYN segments,
      creates a new PCB, and responds with a SYN|ACK. */
@@ -454,7 +455,11 @@ tcp_listen_input(struct tcp_pcb_listen *pcb)
     /* Build an MSS option. */
     optdata = TCP_BUILD_MSS_OPTION();
     /* Send a SYN|ACK together with the MSS option. */
-    tcp_enqueue(npcb, NULL, 0, TCP_SYN | TCP_ACK, 0, (u8_t *)&optdata, 4);
+    rc = tcp_enqueue(npcb, NULL, 0, TCP_SYN | TCP_ACK, 0, (u8_t *)&optdata, 4);
+    if (rc != ERR_OK) {
+      tcp_abandon(npcb, 0);
+      return rc;
+    }
     return tcp_output(npcb);
   }
   return ERR_OK;

src/include/lwip/tcp.h

@@ -96,7 +96,8 @@ err_t            tcp_connect (struct tcp_pcb *pcb, struct ip_addr *ipaddr,
 struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
 #define          tcp_listen(pcb) tcp_listen_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
 
-void             tcp_abort   (struct tcp_pcb *pcb);
+void             tcp_abandon (struct tcp_pcb *pcb, int reset);
+#define          tcp_abort(pcb) tcp_abandon((pcb), 1)
 err_t            tcp_close   (struct tcp_pcb *pcb);
 
 /* Flags for "apiflags" parameter in tcp_write and tcp_enqueue */