client.c

网络通信编程

/*
 ============================================================================
 Name        : client.c
 Author      : maduohe
 Version     :
 Copyright   : Your copyright notice
 Description : Hello World in C, Ansi-style
 ============================================================================
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
#define MAXSIZE 80
#define MYPORT 3490 

void str_cli(FILE *, int);

int main(int argc, char **argv)
  {
    int sockfd, ret, len;
    struct sockaddr_in ser_addr;
    char *myname;
    struct hostent *sh;
    struct in_addr **addrs;

    if (argc !=2)
      {
        printf("parameters not match.");
        exit(0);
      }

    //获取服务器名称
    if ((sh = gethostbyname(argv[1]))== NULL)
      {
        printf("parameters not match");
        exit(0);
      }

    //根据服务器名称获取详细信息
    addrs = (struct in_addr **)sh->h_addr_list;

    //尝试与服务器的各个地址连接，知道连接上其中一个为止
    for (; *addrs!=NULL; addrs++)
      {
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd<0)
          {
            printf("error in socket");
            exit(1);
          }
        //创建套接口
        ser_addr.sin_family = AF_INET;
        ser_addr.sin_port = htons(MYPORT);
        memcpy(&(ser_addr.sin_addr), *addrs, sizeof(struct in_addr));
        bzero(&(ser_addr.sin_zero), 8);
        ret = connect(sockfd,(struct sockaddr *)&ser_addr, sizeof(struct sockaddr));
        if (ret == 0)
          {
            break;
          }
        else//连接成功则跳出循环
          {
            printf("error connecting.");
            close(sockfd);
          }
      }

    //连接不成功则报错并退出
    if (*addrs == NULL)
      {
        printf("can't get connected with server");
        exit(0);
      }

    //数据传输操作
    str_cli(stdin, sockfd);

    //操作结束，关闭socket
    close(sockfd);
    exit(0);

  }

void str_cli(FILE *fp, int sockfd)
  {
    char sends[MAXSIZE], recvs[MAXSIZE];
    int n = 0;
    while (fgets(sends, MAXSIZE, fp)!= NULL)
      {
        send(sockfd, sends, strlen(sends), 0);
        if ((n = recv(sockfd, recvs, MAXSIZE, 0)) == 0)
          {
               printf("error receiving data.");
               exit(1);
          }
        recvs[n]= 0;
        fputs(recvs,stdout);
      }
  }