C++ IPv4与IPv6 socket 编程

Server：

#include <string.h>
#include <iostream>
#include <string>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <stdio.h>
 
using namespace std;
 
int tcp_listen(const char *host, const char *service, const int listen_num = 5)
{
        int listenfd, ret;
        const int on = 1;
        struct addrinfo hints, *res, *ressave;
        //bzero(&hints, sizeof(hints));
        hints.ai_flags = AI_PASSIVE;
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_protocol = IPPROTO_IP;
 
        if (0 != (ret = getaddrinfo(host, service, &hints, &res)))
        {
                cout << "getaddrinfo error: " << gai_strerror(ret) << endl;
                return -1;
        }
 
        ressave = res;
        while(NULL != res)
        {
                if (-1 == (listenfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol)))
                {
                        cout << "create socket error: " << strerror(errno) << endl;
                        res = res->ai_next;
                        continue;
                }
 
                if (-1 == setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)))
                {
                        cout << "setsockopt error: " << strerror(errno) << endl;
                        close(listenfd);
                        res = res->ai_next;
                        continue;
                }
 
                if (-1 == bind(listenfd, res->ai_addr, res->ai_addrlen))
                {
                        cout << "bind error: " << strerror(errno) << endl;
                        close(listenfd);
                        res = res->ai_next;
                        continue;
                }
 
                if (-1 == listen(listenfd, listen_num))
                {
                        cout << "listen error: " << strerror(errno) << endl;
                        close(listenfd);
                        res = res->ai_next;
                        continue;
                }
 
                break;
        }
 
        freeaddrinfo(ressave);
 
        if (NULL == res)
                return -1;
 
        return listenfd;
}
 
int get_addrinfo(const struct sockaddr *addr, string &ip, in_port_t &port)
{
        void *numeric_addr = NULL;
        char addr_buff[INET6_ADDRSTRLEN];
 
        if (AF_INET == addr->sa_family)
        {
                numeric_addr = &((struct sockaddr_in*)addr)->sin_addr;
                port = ntohs(((struct sockaddr_in*)addr)->sin_port);
        }
        else if (AF_INET6 == addr->sa_family)
        {
                numeric_addr = &((struct sockaddr_in6*)addr)->sin6_addr;
                port = ntohs(((struct sockaddr_in6*)addr)->sin6_port);
        }
        else
        {
                return -1;
        }
 
        if (NULL != inet_ntop(addr->sa_family, numeric_addr, addr_buff, sizeof(addr_buff)))
                ip = addr_buff;
        else
                return -1;
 
        return 0;
}
 
int main(int argc, char *argv[])
{
        int listenfd, connfd;
        struct sockaddr_storage cliaddr;
        socklen_t len = sizeof(cliaddr);
        time_t now;
        char buff[128];
 
        if (2 == argc) //指定端口
                listenfd = tcp_listen(NULL, argv[1]);
        else if (3 == argc) //指定本地IP和端口
                listenfd = tcp_listen(argv[1], argv[2]);
        else
        {
                cout << "usage: " << argv[0] << " [<hostname/ipaddress>] <service/port>" << endl;
                return -1;
        }
 
        if (listenfd < 0)
        {
                cout << "call tcp_listen error" << endl;
                return -1;
        }
 
        while (true)
        {
                connfd = accept(listenfd, (struct sockaddr*)&cliaddr, &len);
 
                string ip = "";
                in_port_t port = 0;
                get_addrinfo((struct sockaddr*)&cliaddr, ip, port);
                cout << "client " << ip << "|" << port << " login" << endl;
 
                now = time(NULL);
                snprintf(buff, sizeof(buff) - 1, "%.24s", ctime(&now));
                write(connfd, buff, strlen(buff));
                close(connfd);
        }
 
        close(listenfd);
        return 0;
}

g++ server.cpp -o server

Client:

#include <iostream>
#include <string>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
 
using namespace std;
 
int tcp_connect(const char *host, const char *service)
{
        int sockfd, ret;
        struct addrinfo hints, *res, *ressave;
        //bzero(&hints, sizeof(hints));
        hints.ai_family = AF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_protocol = IPPROTO_IP;
 
        if (0 != (ret = getaddrinfo(host, service, &hints, &res)))
        {
                cout << "getaddrinfo error: " << gai_strerror(ret) << endl;
                return -1;
        }
 
        ressave = res;
        while (NULL != res)
        {
                if (-1 == (sockfd = socket(res->ai_family, res->ai_socktype, res->ai_protocol)))
                {
                        cout << "create socket error: " << strerror(errno) << endl;
                        res = res->ai_next;
                        continue;
                }
 
                if (-1 == connect(sockfd, res->ai_addr, res->ai_addrlen))
                {
                        cout << "connect error: " << strerror(errno) << endl;
                        close(sockfd);
                        res = res->ai_next;
                        continue;
                }
 
                break;
        }

        freeaddrinfo(ressave);
 
        if (NULL == res)
                return -1;
 
        return sockfd;
}
 
int main(int argc, char *argv[])
{
        int sockfd, n;
        char buff[128];
        struct sockaddr_storage cliaddr;

        if (3 != argc)
        {
                cout << "usage: " << argv[0] << " <hostname/ipaddress> <service/port>" << endl;
                return -1;
        }
 
        sockfd = tcp_connect(argv[1], argv[2]);
        if (sockfd < 0)
        {
                cout << "call tcp_connect error" << endl;
                return -1;
        }
 
        //bzero(buff, sizeof(buff));
        while ((n = read(sockfd, buff, sizeof(buff) - 1) > 0))
        {
                cout << buff << endl;
                //bzero(buff, sizeof(buff));
        }
        close(sockfd);
 
        return 0;
}

g++ client.cpp -o client

./server ::1 5000 &
./client ::1 5000

https://blog.csdn.net/ligt0610/article/details/18667595