altcp: fix altcp_tcp_close for LISTEN pcb

See bug #55219

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

src/core/altcp_tcp.c

@@ -162,21 +162,25 @@ static void
 altcp_tcp_remove_callbacks(struct tcp_pcb *tpcb)
 {
   tcp_arg(tpcb, NULL);
-  tcp_recv(tpcb, NULL);
-  tcp_sent(tpcb, NULL);
-  tcp_err(tpcb, NULL);
-  tcp_poll(tpcb, NULL, tpcb->pollinterval);
+  if (tpcb->state != LISTEN) {
+    tcp_recv(tpcb, NULL);
+    tcp_sent(tpcb, NULL);
+    tcp_err(tpcb, NULL);
+    tcp_poll(tpcb, NULL, tpcb->pollinterval);
+  }
 }
 
 static void
 altcp_tcp_setup_callbacks(struct altcp_pcb *conn, struct tcp_pcb *tpcb)
 {
   tcp_arg(tpcb, conn);
-  tcp_recv(tpcb, altcp_tcp_recv);
-  tcp_sent(tpcb, altcp_tcp_sent);
-  tcp_err(tpcb, altcp_tcp_err);
-  /* tcp_poll is set when interval is set by application */
-  /* listen is set totally different :-) */
+  /* this might be called for LISTN when close fails... */
+  if (tpcb->state != LISTEN) {
+    tcp_recv(tpcb, altcp_tcp_recv);
+    tcp_sent(tpcb, altcp_tcp_sent);
+    tcp_err(tpcb, altcp_tcp_err);
+    /* tcp_poll is set when interval is set by application */
+  }
 }
 
 static void