C++ WebSocket库如何支持WebSocket的CORS跨域请求

CORS（跨源资源共享）是一种安全机制，用于在Web浏览器中控制跨域请求

以下是一个使用websocketpp库的简单示例，展示了如何设置CORS头：

#include<iostream>
#include <websocketpp/config/asio_no_tls.hpp>
#include <websocketpp/server.hpp>

typedef websocketpp::server<websocketpp::config::asio> server;

void on_open(server* s, websocketpp::connection_hdl hdl) {
    std::cout << "Connection opened"<< std::endl;
}

void on_message(server* s, websocketpp::connection_hdl hdl, server::message_ptr msg) {
    std::cout << "Received message: "<< msg->get_payload()<< std::endl;
    s->send(hdl, msg->get_payload(), msg->get_opcode());
}

int main() {
    server echo_server;

    try {
        // Set CORS headers
        echo_server.set_access_control_allow_origin("*");
        echo_server.set_access_control_allow_methods("GET, POST, PUT, DELETE, OPTIONS");
        echo_server.set_access_control_allow_headers("Content-Type, Authorization, X-Requested-With, Content-Length, Accept, Origin");

        // Register event handlers
        echo_server.set_open_handler(bind(&on_open, &echo_server, ::_1));
        echo_server.set_message_handler(bind(&on_message, &echo_server, ::_1, ::_2));

        // Listen on port 9002
        echo_server.listen(9002);

        // Start the server accept loop
        echo_server.start_accept();

        // Start the ASIO io_service run loop
        echo_server.run();
    } catch (websocketpp::exception const& e) {
        std::cerr << e.what()<< std::endl;
    } catch (...) {
        std::cerr << "An unknown exception occurred"<< std::endl;
    }

    return 0;
}

这个示例创建了一个简单的WebSocket服务器，允许来自任何源的跨域请求。在实际应用中，你可能需要根据需求调整CORS头，例如限制允许的源、方法和头部。