net: context: Do not check our own ports

There is no need to check our own context when going through
the used ports in the system. This prevents error when binding
in some corner cases.

Fixes #72035

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>

subsys/net/ip/net_context.c

@@ -156,7 +156,8 @@ static inline bool is_in_tcp_time_wait_state(struct net_context *context)
 #endif
 }
 
-static int check_used_port(struct net_if *iface,
+static int check_used_port(struct net_context *context,
+			   struct net_if *iface,
 			   enum net_ip_protocol proto,
 			   uint16_t local_port,
 			   const struct sockaddr *local_addr,
@@ -170,6 +171,10 @@ static int check_used_port(struct net_if *iface,
 			continue;
 		}
 
+		if (context != NULL && context == &contexts[i]) {
+			continue;
+		}
+
 		if (!(net_context_get_proto(&contexts[i]) == proto &&
 		      net_sin((struct sockaddr *)&
 			      contexts[i].local)->sin_port == local_port)) {
@@ -313,7 +318,7 @@ static uint16_t find_available_port(struct net_context *context,
 
 	do {
 		local_port = sys_rand16_get() | 0x8000;
-	} while (check_used_port(NULL, net_context_get_proto(context),
+	} while (check_used_port(context, NULL, net_context_get_proto(context),
 				 htons(local_port), addr, false, false) == -EEXIST);
 
 	return htons(local_port);
@@ -327,7 +332,8 @@ bool net_context_port_in_use(enum net_ip_protocol proto,
 			   uint16_t local_port,
 			   const struct sockaddr *local_addr)
 {
-	return check_used_port(NULL, proto, htons(local_port), local_addr, false, false) != 0;
+	return check_used_port(NULL, NULL, proto, htons(local_port),
+			       local_addr, false, false) != 0;
 }
 
 #if defined(CONFIG_NET_CONTEXT_CHECK)
@@ -794,7 +800,7 @@ int net_context_bind(struct net_context *context, const struct sockaddr *addr,
 
 		ret = 0;
 		if (addr6->sin6_port) {
-			ret = check_used_port(iface,
+			ret = check_used_port(context, iface,
 					      context->proto,
 					      addr6->sin6_port,
 					      addr,
@@ -894,7 +900,7 @@ int net_context_bind(struct net_context *context, const struct sockaddr *addr,
 
 		ret = 0;
 		if (addr4->sin_port) {
-			ret = check_used_port(iface,
+			ret = check_used_port(context, iface,
 					      context->proto,
 					      addr4->sin_port,
 					      addr,