net: connection: Make it possible to update local address

Allow to update the local address on a registered connection when
rebinding.

This is needed for packet sockets, as by default packet socket
will be bound to "any" interface (interface index 0), and interface
index is part of the local address registered for packet socket.
In order to be able to explicitly bind to a specific interface later, it
needs to be possible to update the local address registered for the
connection, as we need to update the interface index, which is used
by net_conn_packet_input() for packet filtering.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

subsys/net/ip/connection.c

@@ -322,56 +322,30 @@ static int net_conn_change_remote(struct net_conn *conn,
 	return 0;
 }
 
-int net_conn_register(uint16_t proto, enum net_sock_type type, uint8_t family,
-		      const struct sockaddr *remote_addr,
-		      const struct sockaddr *local_addr,
-		      uint16_t remote_port,
-		      uint16_t local_port,
-		      struct net_context *context,
-		      net_conn_cb_t cb,
-		      void *user_data,
-		      struct net_conn_handle **handle)
+static int net_conn_change_local(struct net_conn *conn,
+				 const struct sockaddr *local_addr,
+				 uint16_t local_port)
 {
-	struct net_conn *conn;
-	uint8_t flags = 0U;
-	int ret;
-
-	conn = conn_find_handler(context != NULL ? net_context_get_iface(context) : NULL,
-				 proto, family, remote_addr, local_addr,
-				 remote_port, local_port,
-				 context != NULL ?
-					net_context_is_reuseport_set(context) :
-					false);
-	if (conn) {
-		NET_ERR("Identical connection handler %p already found.", conn);
-		return -EADDRINUSE;
-	}
-
-	conn = conn_get_unused();
-	if (!conn) {
-		NET_ERR("Not enough connection contexts. "
-			"Consider increasing CONFIG_NET_MAX_CONN.");
-		return -ENOENT;
-	}
+	NET_DBG("[%zu] connection handler %p changed local",
+		conn - conns, conn);
 
-	if (local_addr) {
+	if (local_addr != NULL) {
 		if (IS_ENABLED(CONFIG_NET_IPV6) &&
 		    local_addr->sa_family == AF_INET6) {
 			memcpy(&conn->local_addr, local_addr,
 			       sizeof(struct sockaddr_in6));
 
 			if (!net_ipv6_is_addr_unspecified(
-				    &net_sin6(local_addr)->
-				    sin6_addr)) {
-				flags |= NET_CONN_LOCAL_ADDR_SPEC;
+					&net_sin6(local_addr)->sin6_addr)) {
+				conn->flags |= NET_CONN_LOCAL_ADDR_SPEC;
 			}
 		} else if (IS_ENABLED(CONFIG_NET_IPV4) &&
 			   local_addr->sa_family == AF_INET) {
 			memcpy(&conn->local_addr, local_addr,
 			       sizeof(struct sockaddr_in));
 
 			if (net_sin(local_addr)->sin_addr.s_addr) {
-				flags |= NET_CONN_LOCAL_ADDR_SPEC;
+				conn->flags |= NET_CONN_LOCAL_ADDR_SPEC;
 			}
 		} else if (IS_ENABLED(CONFIG_NET_SOCKETS_CAN) &&
 			   local_addr->sa_family == AF_CAN) {
@@ -383,10 +357,54 @@ int net_conn_register(uint16_t proto, enum net_sock_type type, uint8_t family,
 			       sizeof(struct sockaddr_ll));
 		} else {
 			NET_ERR("Local address family not set");
-			goto error;
+			return -EINVAL;
 		}
 
-		flags |= NET_CONN_LOCAL_ADDR_SET;
+		conn->flags |= NET_CONN_LOCAL_ADDR_SET;
+	} else {
+		conn->flags &= ~NET_CONN_LOCAL_ADDR_SPEC;
+		conn->flags &= ~NET_CONN_LOCAL_ADDR_SET;
+	}
+
+	if (local_port > 0U) {
+		conn->flags |= NET_CONN_LOCAL_PORT_SPEC;
+		net_sin(&conn->local_addr)->sin_port = htons(local_port);
+	} else {
+		conn->flags &= ~NET_CONN_LOCAL_PORT_SPEC;
+	}
+
+	return 0;
+}
+
+int net_conn_register(uint16_t proto, enum net_sock_type type, uint8_t family,
+		      const struct sockaddr *remote_addr,
+		      const struct sockaddr *local_addr,
+		      uint16_t remote_port,
+		      uint16_t local_port,
+		      struct net_context *context,
+		      net_conn_cb_t cb,
+		      void *user_data,
+		      struct net_conn_handle **handle)
+{
+	struct net_conn *conn;
+	int ret;
+
+	conn = conn_find_handler(context != NULL ? net_context_get_iface(context) : NULL,
+				 proto, family, remote_addr, local_addr,
+				 remote_port, local_port,
+				 context != NULL ?
+					net_context_is_reuseport_set(context) :
+					false);
+	if (conn != NULL) {
+		NET_ERR("Identical connection handler %p already found.", conn);
+		return -EADDRINUSE;
+	}
+
+	conn = conn_get_unused();
+	if (conn == NULL) {
+		NET_ERR("Not enough connection contexts. "
+			"Consider increasing CONFIG_NET_MAX_CONN.");
+		return -ENOENT;
 	}
 
 	if (remote_addr && local_addr) {
@@ -396,25 +414,20 @@ int net_conn_register(uint16_t proto, enum net_sock_type type, uint8_t family,
 		}
 	}
 
-	if (local_port) {
-		flags |= NET_CONN_LOCAL_PORT_SPEC;
-		net_sin(&conn->local_addr)->sin_port = htons(local_port);
-	}
-
 	net_conn_change_callback(conn, cb, user_data);
 
-	conn->flags = flags;
 	conn->proto = proto;
 	conn->type = type;
 	conn->family = family;
 	conn->context = context;
 
-	/*
-	 * Since the net_conn_change_remote() updates the flags in connection,
-	 * must to be called after set the flags to connection.
-	 */
+	ret = net_conn_change_local(conn, local_addr, local_port);
+	if (ret < 0) {
+		goto error;
+	}
+
 	ret = net_conn_change_remote(conn, remote_addr, remote_port);
-	if (ret) {
+	if (ret < 0) {
 		goto error;
 	}
 
@@ -461,7 +474,9 @@ int net_conn_update(struct net_conn_handle *handle,
 		    net_conn_cb_t cb,
 		    void *user_data,
 		    const struct sockaddr *remote_addr,
-		    uint16_t remote_port)
+		    uint16_t remote_port,
+		    const struct sockaddr *local_addr,
+		    uint16_t local_port)
 {
 	struct net_conn *conn = (struct net_conn *)handle;
 	int ret;
@@ -476,6 +491,11 @@ int net_conn_update(struct net_conn_handle *handle,
 
 	net_conn_change_callback(conn, cb, user_data);
 
+	ret = net_conn_change_local(conn, local_addr, local_port);
+	if (ret < 0) {
+		return ret;
+	}
+
 	ret = net_conn_change_remote(conn, remote_addr, remote_port);
 
 	return ret;

subsys/net/ip/connection.h

@@ -170,14 +170,18 @@ static inline int net_conn_unregister(struct net_conn_handle *handle)
  * @param user_data User data supplied by caller.
  * @param remote_addr Remote address
  * @param remote_port Remote port
+ * @param local_addr Local address
+ * @param local_port Local port
  *
  * @return Return 0 if the change succeed, <0 otherwise.
  */
 int net_conn_update(struct net_conn_handle *handle,
 		    net_conn_cb_t cb,
 		    void *user_data,
 		    const struct sockaddr *remote_addr,
-		    uint16_t remote_port);
+		    uint16_t remote_port,
+		    const struct sockaddr *local_addr,
+		    uint16_t local_port);
 
 /**
  * @brief Called by net_core.c when a network packet is received

subsys/net/ip/net_context.c

@@ -2948,26 +2948,6 @@ static int recv_dgram(struct net_context *context,
 
 	ARG_UNUSED(timeout);
 
-	/* If the context already has a connection handler, it means it's
-	 * already registered. In that case, all we have to do is 1) update
-	 * the callback registered in the net_context and 2) update the
-	 * user_data and remote address and port using net_conn_update().
-	 *
-	 * The callback function passed to net_conn_update() must be the same
-	 * function as the one passed to net_conn_register(), not the callback
-	 * set for the net context passed by recv_udp().
-	 */
-	if (context->conn_handler) {
-		context->recv_cb = cb;
-		ret = net_conn_update(context->conn_handler,
-				      net_context_packet_received,
-				      user_data,
-				      context->flags & NET_CONTEXT_REMOTE_ADDR_SET ?
-						&context->remote : NULL,
-				      ntohs(net_sin(&context->remote)->sin_port));
-		return ret;
-	}
-
 	ret = bind_default(context);
 	if (ret) {
 		return ret;
@@ -2999,6 +2979,26 @@ static int recv_dgram(struct net_context *context,
 
 	context->recv_cb = cb;
 
+	/* If the context already has a connection handler, it means it's
+	 * already registered. In that case, all we have to do is 1) update
+	 * the callback registered in the net_context and 2) update the
+	 * user_data and local/remote address and port using net_conn_update().
+	 *
+	 * The callback function passed to net_conn_update() must be the same
+	 * function as the one passed to net_conn_register(), not the callback
+	 * set for the net context passed by recv_udp().
+	 */
+	if (context->conn_handler != NULL) {
+		ret = net_conn_update(context->conn_handler,
+				      net_context_packet_received,
+				      user_data,
+				      context->flags & NET_CONTEXT_REMOTE_ADDR_SET ?
+						&context->remote : NULL,
+				      ntohs(net_sin(&context->remote)->sin_port),
+				      laddr, ntohs(lport));
+		return ret;
+	}
+
 	ret = net_conn_register(net_context_get_proto(context),
 				net_context_get_type(context),
 				net_context_get_family(context),
@@ -3060,10 +3060,17 @@ static int recv_raw(struct net_context *context,
 
 	ARG_UNUSED(timeout);
 
+	ret = bind_default(context);
+	if (ret) {
+		return ret;
+	}
+
+	context->recv_cb = cb;
+
 	/* If the context already has a connection handler, it means it's
 	 * already registered. In that case, all we have to do is 1) update
 	 * the callback registered in the net_context and 2) update the
-	 * user_data using net_conn_update().
+	 * user_data and local address using net_conn_update().
 	 *
 	 * The callback function passed to net_conn_update() must be the same
 	 * function as the one passed to net_conn_register(), not the callback
@@ -3074,17 +3081,10 @@ static int recv_raw(struct net_context *context,
 		ret = net_conn_update(context->conn_handler,
 				      net_context_raw_packet_received,
 				      user_data,
-				      NULL, 0);
-		return ret;
-	}
-
-	ret = bind_default(context);
-	if (ret) {
+				      NULL, 0, local_addr, 0);
 		return ret;
 	}
 
-	context->recv_cb = cb;
-
 	ret = net_conn_register(net_context_get_proto(context),
 				net_context_get_type(context),
 				net_context_get_family(context),
@@ -3137,7 +3137,7 @@ int net_context_recv(struct net_context *context,
 	} else {
 		if (IS_ENABLED(CONFIG_NET_SOCKETS_PACKET) &&
 		    family == AF_PACKET) {
-			struct sockaddr_ll addr;
+			struct sockaddr_ll addr = { 0 };
 
 			addr.sll_family = AF_PACKET;
 			addr.sll_ifindex =