drivers: net: nsos: implement sendmsg()

Implement sendmsg() socket API to have increased compatibility with
components like MQTT client.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

drivers/net/nsos.h

@@ -89,6 +89,21 @@ struct nsos_mid_addrinfo {
 	struct nsos_mid_addrinfo *ai_next;
 };
 
+struct nsos_mid_iovec {
+	void  *iov_base;
+	size_t iov_len;
+};
+
+struct nsos_mid_msghdr {
+	void                  *msg_name;       /* optional socket address, big endian */
+	size_t                 msg_namelen;    /* size of socket address */
+	struct nsos_mid_iovec *msg_iov;        /* scatter/gather array */
+	size_t                 msg_iovlen;     /* number of elements in msg_iov */
+	void                  *msg_control;    /* ancillary data */
+	size_t                 msg_controllen; /* ancillary data buffer len */
+	int                    msg_flags;      /* flags on received message */
+};
+
 static inline void nsos_socket_flag_convert(int *flags_a, int flag_a,
 					    int *flags_b, int flag_b)
 {
@@ -108,6 +123,7 @@ int nsos_adapt_listen(int fd, int backlog);
 int nsos_adapt_accept(int fd, struct nsos_mid_sockaddr *addr, size_t *addrlen);
 int nsos_adapt_sendto(int fd, const void *buf, size_t len, int flags,
 		      const struct nsos_mid_sockaddr *addr, size_t addrlen);
+int nsos_adapt_sendmsg(int fd, const struct nsos_mid_msghdr *msg_mid, int flags);
 int nsos_adapt_recvfrom(int fd, void *buf, size_t len, int flags,
 			struct nsos_mid_sockaddr *addr, size_t *addrlen);
 

drivers/net/nsos_adapt.c

@@ -445,6 +445,49 @@ int nsos_adapt_sendto(int fd, const void *buf, size_t len, int flags,
 	return ret;
 }
 
+int nsos_adapt_sendmsg(int fd, const struct nsos_mid_msghdr *msg_mid, int flags)
+{
+	struct sockaddr_storage addr_storage;
+	struct sockaddr *addr = (struct sockaddr *)&addr_storage;
+	struct msghdr msg;
+	struct iovec *msg_iov;
+	socklen_t addrlen;
+	int ret;
+
+	ret = sockaddr_from_nsos_mid(&addr, &addrlen, msg_mid->msg_name, msg_mid->msg_namelen);
+	if (ret < 0) {
+		return ret;
+	}
+
+	msg_iov = calloc(msg_mid->msg_iovlen, sizeof(*msg_iov));
+	if (!msg_iov) {
+		ret = -ENOMEM;
+		return ret;
+	}
+
+	for (size_t i = 0; i < msg_mid->msg_iovlen; i++) {
+		msg_iov[i].iov_base = msg_mid->msg_iov[i].iov_base;
+		msg_iov[i].iov_len = msg_mid->msg_iov[i].iov_len;
+	}
+
+	msg.msg_name = addr;
+	msg.msg_namelen = addrlen;
+	msg.msg_iov = msg_iov;
+	msg.msg_iovlen = msg_mid->msg_iovlen;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags = 0;
+
+	ret = sendmsg(fd, &msg, socket_flags_from_nsos_mid(flags) | MSG_NOSIGNAL);
+	if (ret < 0) {
+		ret = -errno_to_nsos_mid(errno);
+	}
+
+	free(msg_iov);
+
+	return ret;
+}
+
 int nsos_adapt_recvfrom(int fd, void *buf, size_t len, int flags,
 			struct nsos_mid_sockaddr *addr_mid, size_t *addrlen_mid)
 {

drivers/net/nsos_sockets.c

@@ -672,8 +672,57 @@ return_ret:
 
 static ssize_t nsos_sendmsg(void *obj, const struct msghdr *msg, int flags)
 {
-	errno = ENOTSUP;
+	struct nsos_socket *sock = obj;
-	return -1;
+	struct nsos_mid_sockaddr_storage addr_storage_mid;
+	struct nsos_mid_sockaddr *addr_mid = (struct nsos_mid_sockaddr *)&addr_storage_mid;
+	size_t addrlen_mid = sizeof(addr_storage_mid);
+	struct nsos_mid_msghdr msg_mid;
+	struct nsos_mid_iovec *msg_iov;
+	int flags_mid;
+	int ret;
+
+	ret = socket_flags_to_nsos_mid(flags);
+	if (ret < 0) {
+		goto return_ret;
+	}
+
+	flags_mid = ret;
+
+	ret = sockaddr_to_nsos_mid(msg->msg_name, msg->msg_namelen, &addr_mid, &addrlen_mid);
+	if (ret < 0) {
+		goto return_ret;
+	}
+
+	msg_iov = k_calloc(msg->msg_iovlen, sizeof(*msg_iov));
+	if (!msg_iov) {
+		ret = -ENOMEM;
+		goto return_ret;
+	}
+
+	for (size_t i = 0; i < msg->msg_iovlen; i++) {
+		msg_iov[i].iov_base = msg->msg_iov[i].iov_base;
+		msg_iov[i].iov_len = msg->msg_iov[i].iov_len;
+	}
+
+	msg_mid.msg_name = addr_mid;
+	msg_mid.msg_namelen = addrlen_mid;
+	msg_mid.msg_iov = msg_iov;
+	msg_mid.msg_iovlen = msg->msg_iovlen;
+	msg_mid.msg_control = NULL;
+	msg_mid.msg_controllen = 0;
+	msg_mid.msg_flags = 0;
+
+	ret = nsos_adapt_sendmsg(sock->pollfd.fd, &msg_mid, flags_mid);
+
+	k_free(msg_iov);
+
+return_ret:
+	if (ret < 0) {
+		errno = errno_from_nsos_mid(-ret);
+		return -1;
+	}
+
+	return ret;
 }
 
 static int nsos_recvfrom_with_poll(struct nsos_socket *sock, void *buf, size_t len, int flags,