TCPClientUtility.c

//
// Created by tw on 2018/2/27.
//
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include "Practical.h"

int SetupTCPClientSocket(const char *host, const char *service) {
    struct addrinfo addrCriteria;
    memset(&addrCriteria, 0, sizeof(addrCriteria));
    addrCriteria.ai_family = AF_UNSPEC;
    addrCriteria.ai_socktype = SOCK_STREAM;
    addrCriteria.ai_protocol = IPPROTO_TCP;

    //Get address(es)
    struct addrinfo *servAddr;
    int rtnVal = getaddrinfo(host, service, &addrCriteria, &servAddr);
    if (rtnVal != 0)
        DieWithUserMessage("getaddrinfo() failed", gai_strerror(rtnVal));

    int sock = -1;
    struct addrinfo *addr = servAddr;
    while (addr != NULL)
    {
        sock = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
        if (sock < 0)
        {
            addr = addr->ai_next;
            continue;
        }
        //Establish the connection to the echo server
        if (connect(sock, addr->ai_addr, addr->ai_addrlen) == 0)
            break;
        close(sock);
        sock = -1;
        addr = addr->ai_next;
    }
    freeaddrinfo(servAddr);
    return sock;
}