net: sockets: packet: Make it possible to receive packets when unbound

In order to be able to receive packets on unbound packet sockets (which
should collect packet from all interfaces in such case), it's needed to
register receive callback at the socket layer as soon as the socket is
created.

In additional to that, the default binding for packet sockets need to be
revisited. Packet socket should not be bound to the default interface,
as this way the socket would only be receiving packets from that
particular interface. Instead, leave the interface unspecified in such
case.

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

Author: rlubos

subsys/net/ip/connection.c

@@ -699,13 +699,13 @@ enum net_verdict net_conn_packet_input(struct net_pkt *pkt, uint16_t proto)
 
 		/* Apply protocol-specific matching criteria... */
 
-		if (!(conn->flags & NET_CONN_LOCAL_ADDR_SET)) {
-			continue;
-		}
-
-		local = (struct sockaddr_ll *)&conn->local_addr;
-		if (local->sll_ifindex != net_if_get_by_iface(net_pkt_iface(pkt))) {
-			continue;
+		/* Unbound sockets should collect packets from all interfaces. */
+		if ((conn->flags & NET_CONN_LOCAL_ADDR_SET) != 0U) {
+			local = (struct sockaddr_ll *)&conn->local_addr;
+			if (local->sll_ifindex != 0 &&
+			    local->sll_ifindex != net_if_get_by_iface(net_pkt_iface(pkt))) {
+				continue;
+			}
 		}
 
 		conn_raw_socket_deliver(pkt, conn, false);
@@ -775,7 +775,7 @@ enum net_verdict net_conn_raw_ip_input(struct net_pkt *pkt,
 
 		/* Apply protocol-specific matching criteria... */
 
-		if ((conn->flags & NET_CONN_LOCAL_ADDR_SET) &&
+		if (((conn->flags & NET_CONN_LOCAL_ADDR_SET) != 0U) &&
 		    !conn_addr_cmp(pkt, ip_hdr, &conn->local_addr, false)) {
 			continue; /* wrong local address */
 		}

subsys/net/ip/net_context.c

@@ -770,13 +770,9 @@ static int bind_default(struct net_context *context)
 			return 0;
 		}
 
-		if (iface == NULL) {
-			iface = net_if_get_default();
-		}
-
 		ll_addr.sll_family = AF_PACKET;
 		ll_addr.sll_protocol = htons(ETH_P_ALL);
-		ll_addr.sll_ifindex = net_if_get_by_iface(iface);
+		ll_addr.sll_ifindex = (iface == NULL) ? 0 : net_if_get_by_iface(iface);
 
 		return net_context_bind(context, (struct sockaddr *)&ll_addr,
 					sizeof(ll_addr));
@@ -867,11 +863,13 @@ int net_context_bind(struct net_context *context, const struct sockaddr *addr,
 	/* If we already have connection handler, then it effectively
 	 * means that it's already bound to an interface/port, and we
 	 * don't support rebinding connection to new address/port in
-	 * the code below.
+	 * the code below. Doesn't apply for packet sockets.
 	 * TODO: Support rebinding.
 	 */
-	if (context->conn_handler) {
-		return -EISCONN;
+	if (addr->sa_family != AF_PACKET) {
+		if (context->conn_handler != NULL) {
+			return -EISCONN;
+		}
 	}
 
 	if (IS_ENABLED(CONFIG_NET_IPV6) && addr->sa_family == AF_INET6) {
@@ -1103,13 +1101,8 @@ int net_context_bind(struct net_context *context, const struct sockaddr *addr,
 		}
 
 		iface = net_if_get_by_index(ll_addr->sll_ifindex);
-		if (!iface) {
-			NET_ERR("Cannot bind to interface index %d",
-				ll_addr->sll_ifindex);
-			return -EADDRNOTAVAIL;
-		}
 
-		if (IS_ENABLED(CONFIG_NET_OFFLOAD) &&
+		if (IS_ENABLED(CONFIG_NET_OFFLOAD) && iface != NULL &&
 		    net_if_is_ip_offloaded(iface)) {
 			net_context_set_iface(context, iface);
 
@@ -1121,20 +1114,22 @@ int net_context_bind(struct net_context *context, const struct sockaddr *addr,
 
 		k_mutex_lock(&context->lock, K_FOREVER);
 
-		net_context_set_iface(context, iface);
-
 		net_sll_ptr(&context->local)->sll_family = AF_PACKET;
 		net_sll_ptr(&context->local)->sll_ifindex =
 			ll_addr->sll_ifindex;
 		net_sll_ptr(&context->local)->sll_protocol =
 			ll_addr->sll_protocol;
 
-		net_if_lock(iface);
-		net_sll_ptr(&context->local)->sll_addr =
-			net_if_get_link_addr(iface)->addr;
-		net_sll_ptr(&context->local)->sll_halen =
-			net_if_get_link_addr(iface)->len;
-		net_if_unlock(iface);
+		if (iface != NULL) {
+			net_context_set_iface(context, iface);
+
+			net_if_lock(iface);
+			net_sll_ptr(&context->local)->sll_addr =
+				net_if_get_link_addr(iface)->addr;
+			net_sll_ptr(&context->local)->sll_halen =
+				net_if_get_link_addr(iface)->len;
+			net_if_unlock(iface);
+		}
 
 		NET_DBG("Context %p bind to type 0x%04x iface[%d] %p addr %s",
 			context, htons(net_context_get_proto(context)),
@@ -3147,9 +3142,11 @@ int net_context_recv(struct net_context *context,
 			addr.sll_halen =
 				net_sll_ptr(&context->local)->sll_halen;
 
-			memcpy(addr.sll_addr,
-			       net_sll_ptr(&context->local)->sll_addr,
-			       MIN(addr.sll_halen, sizeof(addr.sll_addr)));
+			if (net_sll_ptr(&context->local)->sll_addr != NULL) {
+				memcpy(addr.sll_addr,
+				       net_sll_ptr(&context->local)->sll_addr,
+				       MIN(addr.sll_halen, sizeof(addr.sll_addr)));
+			}
 
 			ret = recv_raw(context, cb, timeout,
 				       (struct sockaddr *)&addr, user_data);

subsys/net/lib/sockets/sockets_packet.c

@@ -40,6 +40,43 @@ static inline int k_fifo_wait_non_empty(struct k_fifo *fifo,
 	return k_poll(events, ARRAY_SIZE(events), timeout);
 }
 
+static void zpacket_received_cb(struct net_context *ctx,
+				struct net_pkt *pkt,
+				union net_ip_header *ip_hdr,
+				union net_proto_header *proto_hdr,
+				int status,
+				void *user_data)
+{
+	NET_DBG("ctx=%p, pkt=%p, st=%d, user_data=%p", ctx, pkt, status,
+		user_data);
+
+	/* if pkt is NULL, EOF */
+	if (pkt == NULL) {
+		struct net_pkt *last_pkt = k_fifo_peek_tail(&ctx->recv_q);
+
+		if (last_pkt == NULL) {
+			/* If there're no packets in the queue, recv() may
+			 * be blocked waiting on it to become non-empty,
+			 * so cancel that wait.
+			 */
+			sock_set_eof(ctx);
+			k_fifo_cancel_wait(&ctx->recv_q);
+			NET_DBG("Marked socket %p as peer-closed", ctx);
+		} else {
+			net_pkt_set_eof(last_pkt, true);
+			NET_DBG("Set EOF flag on pkt %p", ctx);
+		}
+
+		return;
+	}
+
+	/* Normal packet */
+	net_pkt_set_eof(pkt, false);
+
+	k_fifo_put(&ctx->recv_q, pkt);
+}
+
+
 static int zpacket_socket(int family, int type, int proto)
 {
 	struct net_context *ctx;
@@ -73,46 +110,23 @@ static int zpacket_socket(int family, int type, int proto)
 
 	/* recv_q and accept_q are in union */
 	k_fifo_init(&ctx->recv_q);
-	zvfs_finalize_typed_fd(fd, ctx, (const struct fd_op_vtable *)&packet_sock_fd_op_vtable,
-			    ZVFS_MODE_IFSOCK);
-
-	return fd;
-}
-
-static void zpacket_received_cb(struct net_context *ctx,
-				struct net_pkt *pkt,
-				union net_ip_header *ip_hdr,
-				union net_proto_header *proto_hdr,
-				int status,
-				void *user_data)
-{
-	NET_DBG("ctx=%p, pkt=%p, st=%d, user_data=%p", ctx, pkt, status,
-		user_data);
-
-	/* if pkt is NULL, EOF */
-	if (!pkt) {
-		struct net_pkt *last_pkt = k_fifo_peek_tail(&ctx->recv_q);
 
-		if (!last_pkt) {
-			/* If there're no packets in the queue, recv() may
-			 * be blocked waiting on it to become non-empty,
-			 * so cancel that wait.
-			 */
-			sock_set_eof(ctx);
-			k_fifo_cancel_wait(&ctx->recv_q);
-			NET_DBG("Marked socket %p as peer-closed", ctx);
-		} else {
-			net_pkt_set_eof(last_pkt, true);
-			NET_DBG("Set EOF flag on pkt %p", ctx);
-		}
-
-		return;
+	/* Register the callback so that the socket is able to receive packets
+	 * as soon as it's created.
+	 */
+	ret = net_context_recv(ctx, zpacket_received_cb, K_NO_WAIT,
+			       ctx->user_data);
+	if (ret < 0) {
+		net_context_put(ctx);
+		zvfs_free_fd(fd);
+		errno = -ret;
+		return -1;
 	}
 
-	/* Normal packet */
-	net_pkt_set_eof(pkt, false);
+	zvfs_finalize_typed_fd(fd, ctx, (const struct fd_op_vtable *)&packet_sock_fd_op_vtable,
+			       ZVFS_MODE_IFSOCK);
 
-	k_fifo_put(&ctx->recv_q, pkt);
+	return fd;
 }
 
 static int zpacket_bind_ctx(struct net_context *ctx,
@@ -234,7 +248,6 @@ ssize_t zpacket_sendto_ctx(struct net_context *ctx, const void *buf, size_t len,
 			   int flags, const struct sockaddr *dest_addr,
 			   socklen_t addrlen)
 {
-	const struct sockaddr_ll *ll_addr = (const struct sockaddr_ll *)dest_addr;
 	k_timeout_t timeout = K_FOREVER;
 	int status;
 
@@ -249,32 +262,6 @@ ssize_t zpacket_sendto_ctx(struct net_context *ctx, const void *buf, size_t len,
 		net_context_get_option(ctx, NET_OPT_SNDTIMEO, &timeout, NULL);
 	}
 
-	/* If no interface was set on the context yet, use the one provided in
-	 * the destination address for default binding, unless 0 (any interface)
-	 * was set, in that case let the stack choose the default.
-	 */
-	if (net_context_get_iface(ctx) == NULL && ll_addr->sll_ifindex != 0) {
-		struct net_if *iface = net_if_get_by_index(ll_addr->sll_ifindex);
-
-		if (iface == NULL) {
-			errno = EDESTADDRREQ;
-			return -1;
-		}
-
-		net_context_set_iface(ctx, iface);
-	}
-
-	/* Register the callback before sending in order to receive the response
-	 * from the peer.
-	 */
-
-	status = net_context_recv(ctx, zpacket_received_cb, K_NO_WAIT,
-				  ctx->user_data);
-	if (status < 0) {
-		errno = -status;
-		return -1;
-	}
-
 	status = net_context_sendto(ctx, buf, len, dest_addr, addrlen,
 				    NULL, timeout, ctx->user_data);
 	if (status < 0) {