libwebsockets domo

以下是使用 libwebsockets 实现一个简单的 WebSocket 服务器和客户端的示例：

服务器端代码：

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

static int callback_echo(struct lws *wsi, enum lws_callback_reasons reason,
                    void *user, void *in, size_t len)
{
    switch (reason) {
        case LWS_CALLBACK_ESTABLISHED: {
            printf("connection established\n");
            break;
        }
        case LWS_CALLBACK_RECEIVE: {
            char buf[1024];
            strncpy(buf, (char *)in, len);
            buf[len] = '\0';
            printf("received message: %s\n", buf);
            lws_write(wsi, (unsigned char *)in, len, LWS_WRITE_TEXT);
            break;
        }
        default:
            break;
    }
    return 0;
}

static struct lws_protocols protocols[] = {
    {
        "echo-protocol",
        callback_echo,
        0,
        1024,
    },
    { NULL, NULL, 0, 0 }
};

int main(void)
{
    struct lws_context_creation_info info;
    memset(&info, 0, sizeof(info));
    info.port = 8000;
    info.protocols = protocols;

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

    while (1) {
        lws_service(context, 50);
    }

    lws_context_destroy(context);

    return 0;
}

客户端代码：

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

static int callback_echo(struct lws *wsi, enum lws_callback_reasons reason,
                    void *user, void *in, size_t len)
{
    switch (reason) {
        case LWS_CALLBACK_CLIENT_ESTABLISHED: {
            printf("connection established\n");
            lws_write(wsi, (unsigned char *)"Hello, server!", 14, LWS_WRITE_TEXT);
            break;
        }
        case LWS_CALLBACK_CLIENT_RECEIVE: {
            char buf[1024];
            strncpy(buf, (char *)in, len);
            buf[len] = '\0';
            printf("received message: %s\n", buf);
            break;
        }
        default:
            break;
    }
    return 0;
}

static struct lws_protocols protocols[] = {
    {
        "echo-protocol",
        callback_echo,
        0,
        1024,
    },
    { NULL, NULL, 0, 0 }
};

int main(void)
{
    struct lws_context_creation_info info;
    memset(&info, 0, sizeof(info));
    info.port = CONTEXT_PORT_NO_LISTEN;
    info.protocols = protocols;

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

    struct lws_client_connect_info connect_info;
    memset(&connect_info, 0, sizeof(connect_info));
    connect_info.context = context;
    connect_info.address = "localhost";
    connect_info.port = 8000;
    connect_info.path = "/";
    connect_info.host = "localhost";
    connect_info.origin = "http://localhost";

    struct lws *wsi;
    wsi = lws_client_connect_via_info(&connect_info);
    if (!wsi) {
        printf("Failed to connect to server\n");
        lws_context_destroy(context);
        return -1;
    }

    while (1) {
        lws_service(context, 50);
    }

    lws_context_destroy(context);

    return 0;
}

以上代码实现了一个简单的 WebSocket 服务器和客户端，服务器收到客户端发送的消息后，会将消息原样返回给客户端。