net: sockets: Implement sendto() and recvfrom()

include/net/net_pkt.h

@@ -1359,6 +1359,19 @@ void net_pkt_get_info(struct k_mem_slab **rx,
 		      struct net_buf_pool **rx_data,
 		      struct net_buf_pool **tx_data);
 
+/**
+ * @brief Get source socket address.
+ *
+ * @param pkt Nework packet
+ * @param addr Source socket address
+ * @param addrlen The length of source socket address
+ * @return 0 on success, <0 otherwise.
+ */
+
+int net_pkt_get_src_addr(struct net_pkt *pkt,
+			 struct sockaddr *addr,
+			 socklen_t addrlen);
+
 #if defined(CONFIG_NET_DEBUG_NET_PKT)
 /**
  * @brief Debug helper to print out the buffer allocations

include/net/socket.h

@@ -61,6 +61,10 @@ int zsock_listen(int sock, int backlog);
 int zsock_accept(int sock, struct sockaddr *addr, socklen_t *addrlen);
 ssize_t zsock_send(int sock, const void *buf, size_t len, int flags);
 ssize_t zsock_recv(int sock, void *buf, size_t max_len, int flags);
+ssize_t zsock_sendto(int sock, const void *buf, size_t len, int flags,
+		     const struct sockaddr *dest_addr, socklen_t addrlen);
+ssize_t zsock_recvfrom(int sock, void *buf, size_t max_len, int flags,
+		       struct sockaddr *src_addr, socklen_t *addrlen);
 int zsock_fcntl(int sock, int cmd, int flags);
 int zsock_poll(struct zsock_pollfd *fds, int nfds, int timeout);
 int zsock_inet_pton(sa_family_t family, const char *src, void *dst);
@@ -78,6 +82,8 @@ int zsock_getaddrinfo(const char *host, const char *service,
 #define send zsock_send
 #define recv zsock_recv
 #define fcntl zsock_fcntl
+#define sendto zsock_sendto
+#define recvfrom zsock_recvfrom
 
 #define poll zsock_poll
 #define pollfd zsock_pollfd

subsys/net/ip/net_context.c

@@ -2073,6 +2073,16 @@ static int sendto(struct net_pkt *pkt,
 	}
 #endif /* CONFIG_NET_TCP */
 
+#if defined(CONFIG_NET_UDP)
+	/* Bind default address and port only if UDP */
+	if (net_context_get_ip_proto(context) == IPPROTO_UDP) {
+		ret = bind_default(context);
+		if (ret) {
+			return ret;
+		}
+	}
+#endif /* CONFIG_NET_UDP */
+
 	if (!dst_addr) {
 		return -EDESTADDRREQ;
 	}
@@ -2312,6 +2322,11 @@ static int recv_udp(struct net_context *context,
 		context->conn_handler = NULL;
 	}
 
+	ret = bind_default(context);
+	if (ret) {
+		return ret;
+	}
+
 #if defined(CONFIG_NET_IPV6)
 	if (net_context_get_family(context) == AF_INET6) {
 		if (net_sin6_ptr(&context->local)->sin6_addr) {

subsys/net/ip/net_pkt.c

@@ -1654,6 +1654,61 @@ void net_pkt_get_info(struct k_mem_slab **rx,
 	}
 }
 
+int net_pkt_get_src_addr(struct net_pkt *pkt, struct sockaddr *addr,
+			 socklen_t addrlen)
+{
+	enum net_ip_protocol proto;
+	sa_family_t family;
+
+	if (!addr || !pkt) {
+		return -EINVAL;
+	}
+
+	family = net_pkt_family(pkt);
+
+	if (IS_ENABLED(CONFIG_NET_IPV6) && family == AF_INET6) {
+		struct sockaddr_in6 *addr6 = net_sin6(addr);
+
+		if (addrlen < sizeof(struct sockaddr_in6)) {
+			return -EINVAL;
+		}
+
+		net_ipaddr_copy(&addr6->sin6_addr, &NET_IPV6_HDR(pkt)->src);
+		proto = NET_IPV6_HDR(pkt)->nexthdr;
+
+		if (IS_ENABLED(CONFIG_NET_TCP) && proto == IPPROTO_TCP) {
+			addr6->sin6_port = net_pkt_tcp_data(pkt)->src_port;
+		} else if (IS_ENABLED(CONFIG_NET_UDP) && proto == IPPROTO_UDP) {
+			addr6->sin6_port = net_pkt_udp_data(pkt)->src_port;
+		} else {
+			return -ENOTSUP;
+		}
+
+	} else if (IS_ENABLED(CONFIG_NET_IPV4) && family == AF_INET) {
+		struct sockaddr_in *addr4 = net_sin(addr);
+
+		if (addrlen < sizeof(struct sockaddr_in)) {
+			return -EINVAL;
+		}
+
+		net_ipaddr_copy(&addr4->sin_addr, &NET_IPV4_HDR(pkt)->src);
+		proto = NET_IPV4_HDR(pkt)->proto;
+
+		if (IS_ENABLED(CONFIG_NET_TCP) && proto == IPPROTO_TCP) {
+			addr4->sin_port = net_pkt_tcp_data(pkt)->src_port;
+		} else if (IS_ENABLED(CONFIG_NET_UDP) && proto == IPPROTO_UDP) {
+			addr4->sin_port = net_pkt_udp_data(pkt)->src_port;
+		} else {
+			return -ENOTSUP;
+		}
+
+	} else {
+		return -ENOTSUP;
+	}
+
+	return 0;
+}
+
 #if defined(CONFIG_NET_DEBUG_NET_PKT)
 void net_pkt_print(void)
 {

subsys/net/lib/sockets/sockets.c

@@ -145,11 +145,12 @@ static void zsock_received_cb(struct net_context *ctx, struct net_pkt *pkt,
 	/* Normal packet */
 	net_pkt_set_eof(pkt, false);
 
-	/* We don't care about packet header, so get rid of it asap */
-	header_len = net_pkt_appdata(pkt) - pkt->frags->data;
-	net_buf_pull(pkt->frags, header_len);
-
 	if (net_context_get_type(ctx) == SOCK_STREAM) {
+		/* TCP: we don't care about packet header, get rid of it asap.
+		 * UDP: keep packet header to support recvfrom().
+		 */
+		header_len = net_pkt_appdata(pkt) - pkt->frags->data;
+		net_buf_pull(pkt->frags, header_len);
 		net_context_update_recv_wnd(ctx, -net_pkt_appdatalen(pkt));
 	}
 
@@ -213,12 +214,20 @@ int zsock_accept(int sock, struct sockaddr *addr, socklen_t *addrlen)
 
 ssize_t zsock_send(int sock, const void *buf, size_t len, int flags)
 {
-	ARG_UNUSED(flags);
+	return zsock_sendto(sock, buf, len, flags, NULL, 0);
+}
+
+ssize_t zsock_sendto(int sock, const void *buf, size_t len, int flags,
+		     const struct sockaddr *dest_addr, socklen_t addrlen)
+{
 	int err;
 	struct net_pkt *send_pkt;
 	s32_t timeout = K_FOREVER;
 	struct net_context *ctx = INT_TO_POINTER(sock);
 	size_t max_len = net_if_get_mtu(net_context_get_iface(ctx));
+	enum net_sock_type sock_type = net_context_get_type(ctx);
+
+	ARG_UNUSED(flags);
 
 	if (sock_is_nonblock(ctx)) {
 		timeout = K_NO_WAIT;
@@ -249,7 +258,20 @@ ssize_t zsock_send(int sock, const void *buf, size_t len, int flags)
 		return -1;
 	}
 
-	err = net_context_send(send_pkt, /*cb*/NULL, timeout, NULL, NULL);
+	/* Register the callback before sending in order to receive the response
+	 * from the peer.
+	 */
+	SET_ERRNO(net_context_recv(ctx, zsock_received_cb, K_NO_WAIT, NULL));
+
+	if (sock_type == SOCK_DGRAM) {
+		err = net_context_sendto(send_pkt, dest_addr, addrlen, NULL,
+					 timeout, NULL, NULL);
+	} else if (sock_type == SOCK_STREAM) {
+		err = net_context_send(send_pkt, NULL, timeout, NULL, NULL);
+	} else {
+		__ASSERT(0, "Unknown socket type");
+	}
+
 	if (err < 0) {
 		net_pkt_unref(send_pkt);
 		errno = -err;
@@ -259,7 +281,9 @@ ssize_t zsock_send(int sock, const void *buf, size_t len, int flags)
 	return len;
 }
 
-static inline ssize_t zsock_recv_stream(struct net_context *ctx, void *buf, size_t max_len)
+static inline ssize_t zsock_recv_stream(struct net_context *ctx,
+					void *buf,
+					size_t max_len)
 {
 	size_t recv_len = 0;
 	s32_t timeout = K_FOREVER;
@@ -333,11 +357,18 @@ static inline ssize_t zsock_recv_stream(struct net_context *ctx, void *buf, size
 }
 
 ssize_t zsock_recv(int sock, void *buf, size_t max_len, int flags)
+{
+	return zsock_recvfrom(sock, buf, max_len, flags, NULL, NULL);
+}
+
+ssize_t zsock_recvfrom(int sock, void *buf, size_t max_len, int flags,
+		       struct sockaddr *src_addr, socklen_t *addrlen)
 {
 	ARG_UNUSED(flags);
 	struct net_context *ctx = INT_TO_POINTER(sock);
 	enum net_sock_type sock_type = net_context_get_type(ctx);
 	size_t recv_len = 0;
+	unsigned int header_len;
 
 	if (sock_type == SOCK_DGRAM) {
 
@@ -354,6 +385,19 @@ ssize_t zsock_recv(int sock, void *buf, size_t max_len, int flags)
 			return -1;
 		}
 
+		if (src_addr && addrlen) {
+			int rv;
+
+			rv = net_pkt_get_src_addr(pkt, src_addr, *addrlen);
+			if (rv < 0) {
+				errno = rv;
+				return -1;
+			}
+		}
+		/* Remove packet header since we've handled src addr and port */
+		header_len = net_pkt_appdata(pkt) - pkt->frags->data;
+		net_buf_pull(pkt->frags, header_len);
+
 		recv_len = net_pkt_appdatalen(pkt);
 		if (recv_len > max_len) {
 			recv_len = max_len;

tests/net/socket/udp/prj.conf

@@ -4,7 +4,7 @@ CONFIG_NEWLIB_LIBC=y
 # Networking config
 CONFIG_NETWORKING=y
 CONFIG_NET_IPV4=y
-CONFIG_NET_IPV6=n
+CONFIG_NET_IPV6=y
 CONFIG_NET_UDP=y
 CONFIG_NET_SOCKETS=y
 CONFIG_NET_SOCKETS_POSIX_NAMES=y
@@ -13,13 +13,14 @@ CONFIG_NET_SOCKETS_POSIX_NAMES=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 
 # Network address config
-#CONFIG_NET_APP_SETTINGS=y
-#CONFIG_NET_APP_MY_IPV4_ADDR="192.0.2.1"
-#CONFIG_NET_APP_PEER_IPV4_ADDR="192.0.2.2"
+CONFIG_NET_APP_SETTINGS=y
+CONFIG_NET_APP_MY_IPV4_ADDR="192.0.2.1"
+CONFIG_NET_APP_MY_IPV6_ADDR="2001:db8::1"
 
 # Network debug config
 #CONFIG_NET_LOG=y
 #CONFIG_NET_DEBUG_SOCKETS=y
 #CONFIG_SYS_LOG_NET_LEVEL=4
+CONFIG_MAIN_STACK_SIZE=2048
 
 CONFIG_ZTEST=y