TCP/IP客户机与服务器

TCP客户端
#include <stdio.h>
#include <winsock2.h>
#include <time.h>
#pragma comment(lib, "ws2_32.lib")
int main()
{
    HOSTENT *host_entry;
    char    host_name[256];
    int        n;
    struct WSAData wsadata;
    int     sock, length;
    struct  sockaddr_in  srvaddr;
    struct  sockaddr     tcpaddr;
    int     msgsock;
    char    buf[1024];
    int     rval, len;
    char    c;
    char    data[1024];
    int        i;
if ( WSAStartup(0x0101, &wsadata) == 0)
    {   
sock = socket(AF_INET, SOCK_STREAM, 0);
        if (sock < 0 )
        { 
printf("open socket error\n");
            exit(1);   
        }
        memset(&srvaddr, 0, sizeof(struct sockaddr) );
        srvaddr.sin_family = AF_INET;

        srvaddr.sin_port = htons(5500);
srvaddr.sin_addr.s_addr=inet_addr("172.23.8.21");
        if (connect(sock, (struct sockaddr*)&srvaddr, sizeof(srvaddr)) < 0)
        {
            printf("socket connect error.\n");
            exit(1);
        }
        do 
{
printf("LILI: \n");
            memset(data, 0, 1024);
            i = 0;
            c = getchar();
            while ( c != 10 )
            {
                data[i++] = c;
                c = getchar();
            }
            data[i] = '\0';
            send(sock, data, sizeof(data), 0);
            if ( strcmp(buf, "bye") == 0 )
            {
                closesocket(msgsock);
                WSACleanup();
                exit(1);
            }
memset(buf, 0, sizeof(buf));
            if (( rval = recv(sock, buf, 1024, 0)) < 0 )
            {
                printf("recv sock msg error.\n");