使用libwebsockets-4.3.2写一个C++的websockets server端

以下是一个使用libwebsockets-4.3.2写的C++ Websockets服务端的示例代码：

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

using namespace std;

struct WebsocketServerData {
    int counter;
};

static int callback_websockets(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len)
{
    WebsocketServerData *server_data = (WebsocketServerData*)lws_context_user(lws_get_context(wsi));

    switch (reason) {
        case LWS_CALLBACK_ESTABLISHED:
            cout << "Websocket client connection established" << endl;
            break;

        case LWS_CALLBACK_SERVER_WRITEABLE:
            {
                string message = "Hello, World! " + to_string(server_data->counter);
                unsigned char *buffer = new unsigned char[LWS_SEND_BUFFER_PRE_PADDING + message.length() + LWS_SEND_BUFFER_POST_PADDING];
                memcpy(buffer + LWS_SEND_BUFFER_PRE_PADDING, message.c_str(), message.length());
                lws_write(wsi, buffer + LWS_SEND_BUFFER_PRE_PADDING, message.length(), LWS_WRITE_TEXT);
                delete[] buffer;
                server_data->counter++;
            }
            break;

        case LWS_CALLBACK_RECEIVE:
            cout << "Received message from client: " << string((char*)in, len) << endl;
            lws_callback_on_writable_all_protocol(lws_get_context(wsi), lws_get_protocol(wsi));
            break;

        case LWS_CALLBACK_CLOSED:
            cout << "Websocket connection closed" << endl;
            break;

        default:
            break;
    }

    return 0;
}

int main(int argc, char **argv)
{
    struct lws_context_creation_info context_info;
    struct lws_protocols protocols[] = {
        { "websockets", callback_websockets, sizeof(WebsocketServerData), 0 },
        { NULL, NULL, 0, 0 }
    };
    WebsocketServerData server_data = { 0 };
    int port = 8080;
    int exit_code = 0;

    memset(&context_info, 0, sizeof(context_info));
    context_info.port = port;
    context_info.protocols = protocols;
    context_info.user = &server_data;

    struct lws_context *context = lws_create_context(&context_info);
    if (!context) {
        cerr << "Failed to create libwebsocket context" << endl;
        exit_code = 1;
        goto cleanup;
    }

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

cleanup:
    if (context) {
        lws_context_destroy(context);
    }

    return exit_code;
}

这个示例代码创建了一个Websocket服务端，监听指定的端口，并且每收到一条客户端消息就回复一条消息。你可以根据你的需求调整服务端回复消息的内容和频率。