5-5-testaccept.c

//g++ 5-5-testaccept.c -o testaccept

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

int main(int argc, const char *argv[])
{
    
    if (argc <= 2) 
    {
        printf("Usage: %s ip_address port_number\n", basename(argv[0]));
        return 1;
    }
    const char *ip = argv[1];
    int port       = atoi(argv[2]);

    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);

    int sock = socket(PF_INET, SOCK_STREAM, 0);
    assert(sock >= 0);

    int ret = bind(sock, (struct sockaddr *)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(sock, 5);
    assert(ret != -1);
    /*暂停20秒以等待客户端连接和相关操作（掉线或者退出）完成*/
    sleep(20);
    struct sockaddr_in client;
    socklen_t client_addrlength = sizeof(client);
    int connfd = accept(sock, (struct sockaddr *)&client, &client_addrlength);
    if (connfd < 0) 
    {
        printf("errno is: %d \n", errno);
    }
    else
    {
        /*accept successfully, then print client's ip and port*/
        char remote[INET_ADDRSTRLEN];
        printf("connected with ip: %s and port: %d\n", inet_ntop(AF_INET, 
                    &client.sin_addr, remote, INET_ADDRSTRLEN), ntohs(client.sin_port));
        close(connfd);
    }

    close(sock);

    return 0;
}