Websocket++ TLS客户端报错：必需的tls_init_handler未设置

我用Websocket++开发客户端程序，参考zaphoyd官网教程实现，但教程未覆盖TLS客户端内容，自行修改代码实现了TLS客户端（代码见下方）。尝试连接wss://echo.websocket.events这类服务器时，始终收到日志错误「[fatal] Required tls_init handler not present.」，连接失败。曾尝试将处理器移入connection_metadata类，但遇到函数签名错误。已安装OpenSSL 1.1.1f，使用CMake构建并配置了find_package(OpenSSL REQUIRED)，请问问题出在哪？

#include <cstdlib>
#include <iostream>
#include <map>
#include <string>
#include <sstream>

#include <websocketpp/config/asio_client.hpp> 
#include <boost/asio.hpp>
#include <boost/asio/ssl.hpp>
#include <boost/asio/ssl/context.hpp> 
#include <websocketpp/client.hpp> 

#include <websocketpp/common/thread.hpp>
#include <websocketpp/common/memory.hpp>

typedef websocketpp::client<websocketpp::config::asio_tls_client> client;

class connection_metadata {
    private:
        int m_id;
        websocketpp::connection_hdl m_hdl;
        std::string m_status;
        std::string m_uri;
        std::string m_server;
        std::string m_error_reason;

    public:
        typedef websocketpp::lib::shared_ptr<connection_metadata> ptr;

        connection_metadata(int id, websocketpp::connection_hdl hdl, std::string uri):
        m_id(id),
        m_hdl(hdl),
        m_status("Connecting"),
        m_uri(uri),
        m_server("N/A")
        {}

        int get_id(){return m_id;}
        websocketpp::connection_hdl get_hdl(){ return m_hdl;}
        std::string get_status(){return m_status;}
        
        void on_open(client * c, websocketpp::connection_hdl hdl){
            m_status = "Open";

            client::connection_ptr con = c->get_con_from_hdl(hdl);
            m_server = con->get_response_header("Server");
        }

        void on_fail(client * c, websocketpp::connection_hdl hdl){
            m_status = "Failed";

            client::connection_ptr con = c->get_con_from_hdl(hdl);
            m_server = con->get_response_header("Server");
            m_error_reason = con->get_ec().message();
        }

        void on_close(client * c, websocketpp::connection_hdl hdl){
            m_status = "Closed";

            client::connection_ptr con = c->get_con_from_hdl(hdl);
            std::stringstream s;
            s << "Close code: " << con->get_remote_close_code() << "("
              << websocketpp::close::status::get_string(con->get_remote_close_code())
              << "), Close reason: " << con->get_remote_close_reason();
            
            m_error_reason = s.str();
        }

        friend std::ostream &operator<< (std::ostream &out, connection_metadata const &data);
};

std::ostream &operator<< (std::ostream &out, connection_metadata const &data){
    out << "> URI: " << data.m_uri << "\n"
        << "> Status: " << data.m_status << "\n"
        << "> Remote Server: " << (data.m_server.empty() ? "None Specified" : data.m_server) << "\n"
        << "> Error/close reason: " << (data.m_error_reason.empty() ? "N/A" : data.m_error_reason);
 
    return out;
}

class websocket_endpoint {
    private:
        typedef std::map<int,connection_metadata::ptr> con_list;

        client m_endpoint;
        websocketpp::lib::shared_ptr<websocketpp::lib::thread> m_thread;

        con_list m_connection_list;
        int m_next_id;

    public:
        websocket_endpoint(): m_next_id(0) {
            m_endpoint.set_access_channels(websocketpp::log::alevel::all);
            m_endpoint.set_error_channels(websocketpp::log::elevel::all);

            m_endpoint.init_asio();
            m_endpoint.start_perpetual();

            m_thread.reset(new websocketpp::lib::thread(&client::run, &m_endpoint));
        }

        ~websocket_endpoint() {
            m_endpoint.stop_perpetual();
    
            for (con_list::const_iterator it = m_connection_list.begin(); it != m_connection_list.end(); ++it) {
                if (it->second->get_status() != "Open") {
                    continue;
                }
                
                std::cout << "> Closing connection " << it->second->get_id() << std::endl;
                
                websocketpp::lib::error_code ec;
                m_endpoint.close(it->second->get_hdl(), websocketpp::close::status::going_away, "", ec);
                if (ec) {
                    std::cout << "> Error closing connection " << it->second->get_id() << ": "  
                            << ec.message() << std::endl;
                }
            }
            
            m_thread->join();
        }

        int connect (std::string const &uri) {
            websocketpp::lib::error_code ec;
            
            client::connection_ptr con = m_endpoint.get_connection(uri, ec);

            if(ec){
                std::cout << "Connection initialization error: " << ec.message() << std::endl;
                return -1;
            }

            int new_id = m_next_id++;
            connection_metadata::ptr metadata_ptr(new connection_metadata(new_id, con->get_handle(), uri));
            m_connection_list[new_id] = metadata_ptr;

            con->set_open_handler(websocketpp::lib::bind(
                                  &connection_metadata::on_open,
                                  metadata_ptr,
                                  &m_endpoint,
                                  websocketpp::lib::placeholders::_1
                                  ));

            con->set_fail_handler(websocketpp::lib::bind(
                                  &connection_metadata::on_fail,
                                  metadata_ptr,
                                  &m_endpoint,
                                  websocketpp::lib::placeholders::_1
                                  ));
            con->set_close_handler(websocketpp::lib::bind(
                                   &connection_metadata::on_close,
                                   metadata_ptr,
                                   &m_endpoint,
                                   websocketpp::lib::placeholders::_1
                                  ));
            con->set_tls_init_handler([](websocketpp::connection_hdl){
                                        boost::asio::ssl::context context(boost::asio::ssl::context::tlsv1);
                                        return websocketpp::lib::make_shared<boost::asio::ssl::context>(std::move(context));
                                        });
            m_endpoint.connect(con);
    
            return new_id;
        }

        connection_metadata::ptr get_metadata(int id) const {
            con_list::const_iterator metadata_it = m_connection_list.find(id);
            if (metadata_it == m_connection_list.end()) {
                return connection_metadata::ptr();
            } else {
                return metadata_it->second;
            }
        }

        void close(int id, websocketpp::close::status::value code, std::string reason) {
            websocketpp::lib::error_code ec;

            con_list::iterator metadata_it = m_connection_list.find(id);
            if (metadata_it == m_connection_list.end()) {
                std::cout << "> No connection found with id " << id << std::endl;
                return;
            }

            m_endpoint.close(metadata_it->second->get_hdl(), code, "", ec);
            std::cout << "Connection closed with reason: " << reason << std::endl;
        }
};

int main(){
    bool done = false;
    std::string input;
    websocket_endpoint endpoint;

    while(!done) {
        std::cout << "Enter Command: ";
        std::getline(std::cin, input);

        if(input == "quit"){
            done = true;
        } 
        else if(input == "help"){
            std::cout << "\nCommand List:\n"
            << "help: Displays this help text\n"
            << "quit: exits the program\n"
            << "connect <URI>: creates a connection with the given URI\n"
            << "close <id> <code (optional)> <reason (optional)>: closes the connection with the given id with optionally specifiable exit_code and/or reason\n"
            << "show <id>: Gets the metadata of the connection with the given id\n"
            << std::endl;
        }
        else if (input.substr(0,7) == "connect") {
            int id = endpoint.connect(input.substr(8));
            if (id != -1) {
                std::cout << "> Created connection with id " << id << std::endl;
            }
        } 
        else if (input.substr(0,4) == "show") {
            int id = atoi(input.substr(5).c_str());
 
            connection_metadata::ptr metadata = endpoint.get_metadata(id);
            if (metadata) {
                std::cout << *metadata << std::endl;
            } else {
                std::cout << "> Unknown connection id " << id << std::endl;
            }
        }
        else if(input.substr(0, 5) == "close"){
            std::stringstream ss(input);

            std::string cmd;
            int id;
            int close_code = websocketpp::close::status::normal;
            std::string reason;

            ss >> cmd >> id >> close_code;
            std::getline(ss, reason);

            endpoint.close(id, close_code, reason);
        }
        else{
            std::cout << "Unrecognized command" << std::endl;
        }
    }
    return 0;
}

核心问题 #

1. TLS处理器设置时机错误：你在调用m_endpoint.get_connection(uri, ec)后才设置tls_init_handler，但Websocket++在创建连接对象时就会检查TLS处理器是否存在，此时处理器尚未配置，直接触发致命错误。
2. TLS协议版本过时：代码中指定了tlsv1版本，这是已被淘汰的协议，现代WSS服务器大多不再支持，会导致握手失败。

修复步骤 #

1. 调整TLS处理器设置时机（全局设置推荐） #

在websocket_endpoint构造函数中设置全局TLS初始化处理器，确保创建连接对象前TLS配置已就绪：

websocket_endpoint(): m_next_id(0) {
    m_endpoint.set_access_channels(websocketpp::log::alevel::all);
    m_endpoint.set_error_channels(websocketpp::log::elevel::all);

    // 设置全局TLS初始化处理器
    m_endpoint.set_tls_init_handler([](websocketpp::connection_hdl) {
        // 使用TLSv1.2版本，兼容绝大多数现代服务器
        boost::asio::ssl::context ctx(boost::asio::ssl::context::tlsv12);
        try {
            // 启用证书验证，避免安全风险
            ctx.set_options(boost::asio::ssl::context::default_workarounds |
                            boost::asio::ssl::context::no_sslv2 |
                            boost::asio::ssl::context::no_sslv3 |
                            boost::asio::ssl::context::single_dh_use);
        } catch (std::exception& e) {
            std::cout << "TLS context setup error: " << e.what() << std::endl;
        }
        return websocketpp::lib::make_shared<boost::asio::ssl::context>(std::move(ctx));
    });

    m_endpoint.init_asio();
    m_endpoint.start_perpetual();

    m_thread.reset(new websocketpp::lib::thread(&client::run, &m_endpoint));
}

2. 删除局部TLS处理器设置 #

移除connect函数中这段代码：

con->set_tls_init_handler([](websocketpp::connection_hdl){
    boost::asio::ssl::context context(boost::asio::ssl::context::tlsv1);
    return websocketpp::lib::make_shared<boost::asio::ssl::context>(std::move(context));
});

3. （可选）单个连接定制TLS配置 #

如果需要为不同连接设置不同TLS参数，需在get_connection后立刻设置处理器，且必须在调用m_endpoint.connect(con)前完成。也可以用bind绑定connection_metadata类成员函数，正确签名示例：
在connection_metadata中添加成员函数：

websocketpp::lib::shared_ptr<boost::asio::ssl::context> on_tls_init(websocketpp::connection_hdl) {
    boost::asio::ssl::context ctx(boost::asio::ssl::context::tlsv12);
    // 自定义配置...
    return websocketpp::lib::make_shared<boost::asio::ssl::context>(std::move(ctx));
}

在connect函数中绑定：

con->set_tls_init_handler(websocketpp::lib::bind(
    &connection_metadata::on_tls_init,
    metadata_ptr,
    websocketpp::lib::placeholders::_1
));

内容的提问来源于stack exchange，提问作者insipidintegrator