Enable socket-api recvmsg() and sendmsg() (#1042)

Implement socket-api `recvmsg()` and `sendmsg()` for wasm app,
add sample and update document.

samples/socket-api/wasm-src/CMakeLists.txt

@@ -78,3 +78,4 @@ endfunction()
 
 compile_with_clang(tcp_server.c)
 compile_with_clang(tcp_client.c)
+compile_with_clang(send_recv.c)

samples/socket-api/wasm-src/send_recv.c

@@ -0,0 +1,209 @@
+/*
+ * Copyright (C) 2019 Intel Corporation.  All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#ifdef __wasi__
+#include <wasi_socket_ext.h>
+#endif
+
+static pthread_mutex_t lock = { 0 };
+static pthread_cond_t cond = { 0 };
+static bool server_is_ready = false;
+
+void *
+run_as_server(void *arg)
+{
+    int sock = -1, on = 1;
+    struct sockaddr_in addr = { 0 };
+    int addrlen = 0;
+    int new_sock = -1;
+    char *buf[] = {
+        "The stars shine down", "It brings us light", "Light comes down",
+        "To make us paths",     "It watches us",      "And mourns for us",
+    };
+    struct iovec iov[] = {
+        { .iov_base = buf[0], .iov_len = strlen(buf[0]) + 1 },
+        { .iov_base = buf[1], .iov_len = strlen(buf[1]) + 1 },
+        { .iov_base = buf[2], .iov_len = strlen(buf[2]) + 1 },
+        { .iov_base = buf[3], .iov_len = strlen(buf[3]) + 1 },
+        { .iov_base = buf[4], .iov_len = strlen(buf[4]) + 1 },
+        { .iov_base = buf[5], .iov_len = strlen(buf[5]) + 1 },
+    };
+    struct msghdr msg = { .msg_iov = iov, .msg_iovlen = 6 };
+    ssize_t send_len = 0;
+
+    pthread_mutex_lock(&lock);
+    sock = socket(AF_INET, SOCK_STREAM, 0);
+    if (sock < 0) {
+        perror("Create a socket failed");
+        goto RETURN;
+    }
+
+#ifndef __wasi__
+    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on))) {
+        perror("Setsockopt failed");
+        goto RETURN;
+    }
+#endif
+
+    /* 0.0.0.0:1234 */
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(1234);
+    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+
+    addrlen = sizeof(addr);
+    if (bind(sock, (struct sockaddr *)&addr, addrlen) < 0) {
+        perror("Bind failed");
+        goto UNLOCK_SHUTDOWN;
+    }
+
+    if (listen(sock, 0) < 0) {
+        perror("Listen failed");
+        goto UNLOCK_SHUTDOWN;
+    }
+
+    server_is_ready = true;
+    pthread_cond_signal(&cond);
+    pthread_mutex_unlock(&lock);
+
+    printf("Server is online ... \n");
+
+    new_sock = accept(sock, (struct sockaddr *)&addr, (socklen_t *)&addrlen);
+    if (new_sock < 0) {
+        perror("Accept failed");
+        goto SHUTDOWN;
+    }
+
+    printf("Start sending. \n");
+    send_len = sendmsg(new_sock, &msg, 0);
+    if (send_len < 0) {
+        perror("Sendmsg failed");
+        goto SHUTDOWN;
+    }
+    printf("Send %ld bytes successfully!\n", send_len);
+
+SHUTDOWN:
+    shutdown(sock, SHUT_RD);
+    return NULL;
+
+UNLOCK_SHUTDOWN:
+    shutdown(sock, SHUT_RD);
+RETURN:
+    pthread_mutex_unlock(&lock);
+    return NULL;
+}
+
+void *
+run_as_client(void *arg)
+{
+    int sock = -1;
+    struct sockaddr_in addr = { 0 };
+    char buf[256] = { 0 };
+    struct iovec iov = { .iov_base = buf, .iov_len = sizeof(buf) };
+    struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
+    ssize_t recv_len = 0;
+
+    pthread_mutex_lock(&lock);
+    while (false == server_is_ready) {
+        pthread_cond_wait(&cond, &lock);
+    }
+    pthread_mutex_unlock(&lock);
+
+    printf("Client is running...\n");
+    sock = socket(AF_INET, SOCK_STREAM, 0);
+    if (sock < 0) {
+        perror("Create a socket failed");
+        goto RETURN;
+    }
+
+    /* 127.0.0.1:1234 */
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(1234);
+    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+
+    if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+        perror("Connect failed");
+        goto UNLOCK_SHUTDOWN;
+    }
+
+    printf("Start receiving. \n");
+    recv_len = recvmsg(sock, &msg, 0);
+    if (recv_len < 0) {
+        perror("Recvmsg failed");
+        goto SHUTDOWN;
+    }
+
+    printf("Receive %ld bytes successlly!\n", recv_len);
+    printf("Data:\n");
+
+    uint8_t i = 0;
+    char *s = msg.msg_iov->iov_base;
+    for (i = 0; i < 6; i++) {
+        printf("  %s\n", s);
+        s += strlen(s) + 1;
+    }
+
+SHUTDOWN:
+    shutdown(sock, SHUT_RD);
+    return NULL;
+
+UNLOCK_SHUTDOWN:
+    shutdown(sock, SHUT_RD);
+RETURN:
+    pthread_mutex_unlock(&lock);
+    return NULL;
+}
+
+int
+main(int argc, char *argv[])
+{
+    pthread_t cs[2] = { 0 };
+    uint8_t i = 0;
+    int ret = EXIT_SUCCESS;
+
+    if (pthread_mutex_init(&lock, NULL)) {
+        perror("Initialize mutex failed");
+        ret = EXIT_FAILURE;
+        goto RETURN;
+    }
+
+    if (pthread_cond_init(&cond, NULL)) {
+        perror("Initialize condition failed");
+        ret = EXIT_FAILURE;
+        goto DESTROY_MUTEX;
+    }
+
+    if (pthread_create(&cs[0], NULL, run_as_server, NULL)) {
+        perror("Create a server thread failed");
+        ret = EXIT_FAILURE;
+        goto DESTROY_COND;
+    }
+
+    if (pthread_create(&cs[1], NULL, run_as_client, NULL)) {
+        perror("Create a client thread failed");
+        ret = EXIT_FAILURE;
+        goto DESTROY_COND;
+    }
+
+    for (i = 0; i < 2; i++) {
+        pthread_join(cs[i], NULL);
+    }
+
+DESTROY_COND:
+    pthread_cond_destroy(&cond);
+DESTROY_MUTEX:
+    pthread_mutex_destroy(&lock);
+RETURN:
+    return ret;
+}