C语言WebSocket 代码例子

在 C 语言中连接 WebSocket 需要使用第三方库，例如 libwebsockets。

以下是一个简单的示例代码，演示如何使用 libwebsockets 库连接 WebSocket：

#include <libwebsockets.h>
#include <string.h>
#include <stdio.h>

static int websocket_callback(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len) {
    switch (reason) {
        case LWS_CALLBACK_CLIENT_ESTABLISHED:
            printf("WebSocket client connected\n");
            break;
        case LWS_CALLBACK_CLIENT_RECEIVE:
            printf("Received data: %s\n", (char *)in);
            break;
        case LWS_CALLBACK_CLIENT_WRITEABLE: {
            char *message = "Hello, WebSocket server!";
            unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + strlen(message) + LWS_SEND_BUFFER_POST_PADDING];
            int len = sprintf((char *)&buf[LWS_SEND_BUFFER_PRE_PADDING], "%s", message);
            lws_write(wsi, &buf[LWS_SEND_BUFFER_PRE_PADDING], len, LWS_WRITE_TEXT);
            break;
        }
        case LWS_CALLBACK_CLOSED:
            printf("WebSocket client closed\n");
            break;
        default:
            break;
    }
    return 0;
}

int main() {
    struct lws_context_creation_info info;
    struct lws_client_connect_info connect_info;
    struct lws_context *context;
    struct lws *wsi;
    const char *protocol = "ws";
    const char *address = "localhost:8080";
    int port = 80;
    int use_ssl = 0;
    int ret;

    memset(&info, 0, sizeof(info));
    info.port = CONTEXT_PORT_NO_LISTEN;
    info.protocols = lws_protocols;
    info.gid = -1;
    info.uid = -1;

    context = lws_create_context(&info);
    if (!context) {
        printf("Failed to create WebSockets context\n");
        return -1;
    }

    memset(&connect_info, 0, sizeof(connect_info));
    connect_info.context = context;
    connect_info.address = address;
    connect_info.port = port;
    connect_info.path = "/";
    connect_info.host = lws_canonical_hostname(context);
    connect_info.origin = lws_canonical_hostname(context);
    connect_info.protocol = protocol;
    connect_info.ssl_connection = use_ssl;

    wsi = lws_client_connect_via_info(&connect_info);
    if (!wsi) {
        printf("Failed to connect to WebSocket server\n");
        return -1;
    }

    while (1) {
        ret = lws_service(context, 10);
        if (ret < 0) {
            printf("WebSockets service failed\n");
            break;
        }
    }

    lws_context_destroy(context);
    return 0;
}

这个示例代码使用了 libwebsockets 库的一些基本函数来实现 WebSocket 连接和数据收发。其中，websocket_callback 函数是 WebSocket 连接的回调函数，用于处理不同的事件。

请注意，这个示例代码仅作为演示用途，实际使用中可能需要根据具体情况进行修改。