Socket Programming in C++

I write a simple client/server example in C/C++ without any extra functionalites. You may built your own use case referring to this example. The origin code is attached here and also open sources in github!.

Client

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char **argv) {
    struct sockaddr_in server_addr;     // set server addr and port
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr(argv[1]);
    server_addr.sin_port = htons(8000);  // server default port

    int sock_client;
    char send_buf[65536];
    memset(send_buf, '\0', sizeof(send_buf));
    char *send_content = "I am client";
    strcpy(send_buf, send_content);

    if ((sock_client = socket(AF_INET,SOCK_STREAM, 0)) < 0) {
        return 0;
    }

    //connect server, return 0 with success, return -1 with error
    if (connect(sock_client, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0)
    {
        perror("connect");
        return 0;
    }

    char server_ip[INET_ADDRSTRLEN]="";
    inet_ntop(AF_INET, &server_addr.sin_addr, server_ip, INET_ADDRSTRLEN);
    printf("connected server(%s:%d). \n", server_ip, ntohs(server_addr.sin_port));

    //send a message to server
    send(sock_client, send_buf, strlen(send_buf), 0);
    close(sock_client);

    return 0;
}

Server

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h> // for close
#include <string.h>


int main(int argc, char *argv[]) {

    int server_sockfd;      // server socket fd 
    struct sockaddr_in server_addr;     // server info struct
    server_addr.sin_family=AF_INET;     // TCP/IP
    server_addr.sin_addr.s_addr=INADDR_ANY;     // server addr--permit all connection
    server_addr.sin_port=htons(8000);       // server port

    /*创建服务器端套接字--IPv4协议，面向连接通信，TCP协议*/
    /* create socket fd with IPv4 and TCP protocal*/
    if((server_sockfd=socket(PF_INET,SOCK_STREAM,0))<0) {  
                    perror("socket error");
                    return 1;
    }

    /*将套接字绑定到服务器的网络地址上*/
    /* bind socket with server addr */
    if(bind(server_sockfd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))<0) {
                    perror("bind error");
                    return 1;
    }


    /*监听连接请求--监听队列长度为20*/
    /* listen connection request with a queue length of 20 */
    if(listen(server_sockfd,20)<0) {
                    perror("listen error");
                    return 1;
    }
    printf("listen success.\n");

    char recv_buf[65536];
    memset(recv_buf, '\0', sizeof(recv_buf));

    while (1) {
        struct sockaddr_in client_addr;
        socklen_t length = sizeof(client_addr);
        //进程阻塞在accept上，成功返回非负描述字，出错返回-1
        // block on accept until positive fd or error
        int conn = accept(server_sockfd, (struct sockaddr*)&client_addr,&length);
        if(conn<0) {
            perror("connect");
            return -1;
        }

        printf("new client accepted.\n");

        char client_ip[INET_ADDRSTRLEN] = "";
        inet_ntop(AF_INET, &client_addr.sin_addr, client_ip, INET_ADDRSTRLEN);

        while(recv(conn, recv_buf, sizeof(recv_buf), 0) > 0 ){
            printf("recv %s from client(%s:%d). \n", recv_buf, client_ip, ntohs(client_addr.sin_port));
            memset(recv_buf, '\0', strlen(recv_buf));
            break;
        }
    }

    printf("closed. \n");
    close(server_sockfd);
    return 0;
}

There is no socket API in the C++ Standard. The POSIX C API is fairly portable (the GNU libC documentation provides examples of UDP and TCP clients and servers that I usually turn to when I'm scratching together another server), or you could use the Boost.ASIO library for a more C++ experience....

You can find a working client-server program here: Beej's Guide to Network Programming

A good C++ networking library is ACE. The only problem is that there aren't any good tutorials online that I have found. This book is pretty good though.