获取正在监听的主机列表_监听主机-优快云博客

本文链接：https://blog.youkuaiyun.com/wangzhicheng1983/article/details/102991140

本文介绍了一种使用C++进行网络编程的方法，通过net_utility类实现对指定域名和端口的监听主机列表获取。代码中包含了信号处理、套接字创建、地址解析、连接尝试及地址转换等关键步骤，适用于需要在网络环境中获取监听主机信息的场景。

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#include <unistd.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <signal.h>
#include <iostream>
#include <string>
#include <vector>
class net_utility {
public:
    static void listened_host_list(const char *domain, const char *port, std::vector<std::string>&host_list) {
        signal(SIGPIPE, SIG_IGN);
        addrinfo *result = nullptr;
        addrinfo hints = { 0 };
        hints.ai_family = AF_UNSPEC;            // either IPv4 or IPv6
        hints.ai_socktype = SOCK_STREAM; 
        if (0 != getaddrinfo(domain, port, &hints, &result)) {
            std::cerr << "getaddrinfo for domain:" << domain << " port:" << port << "failed." << std::endl;
            return;
        }
        char address[INET6_ADDRSTRLEN] = "";
        const char *retval = nullptr;
        struct timeval timeo = {10, 0};         // 10s
        socklen_t len = sizeof(timeo);
        for (auto addr = result;addr != nullptr;addr = addr->ai_next) {      
            int client_fd = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);  
            if (client_fd < 0) {
                continue;
            }
            setsockopt(client_fd, SOL_SOCKET, SO_SNDTIMEO, &timeo, len);
            if (connect(client_fd, addr->ai_addr, addr->ai_addrlen) < 0) {
                std::cerr << "connect failed." << std::endl;
                close(client_fd);
                continue;
            }
            switch(addr->ai_family) {
                case AF_INET:
                    retval = inet_ntop(addr->ai_family, &(reinterpret_cast<sockaddr_in *>(addr->ai_addr)->sin_addr), address, INET6_ADDRSTRLEN);
                    break;
                case AF_INET6:
                    retval = inet_ntop(addr->ai_family, &(reinterpret_cast<sockaddr_in6 *>(addr->ai_addr)->sin6_addr), address, INET6_ADDRSTRLEN);
                    break;
                default:
                    retval = nullptr;
                    break;
            }
            host_list.emplace_back(address);
            close(client_fd);
        }
        freeaddrinfo(result);
    }
};
int main(){
    const char *ip = "192.168.2.109";
    const char *port = "26311";
    std::vector<std::string>host_list;
    net_utility::listened_host_list(ip, port, host_list);
    for (auto &host : host_list) {
        std::cout << host << " is listening" << std::endl;
    }

    return 0;
}