tcpclient.c

socket编程TCP server端与client端连通程序

/*
客户每次用一个随机的端口连接服务器,并接收来自服务器的欢迎信息
,然后打印出来(tcpclient).运行的时候接受一个参数,也就是服务器的ip地址
*/

/* Tcp client program, It is a simple example only.

 * zhengsh 200520602061 2

 * connect to server, and echo a message from server.

 */

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

#define SERVER_PORT 20000 // define the defualt connect port id
#define CLIENT_PORT ((20001+rand())%65536) // define the defualt client port as a random port
#define BUFFER_SIZE 255
#define REUQEST_MESSAGE "welcome to connect the server.\n"

void usage(char *name)
{
       printf("usage: %s IpAddr\n",name);
}

int main(int argc, char **argv)
{     
       int servfd,clifd,length = 0;
       struct sockaddr_in servaddr,cliaddr;
       socklen_t socklen = sizeof(servaddr);
       char buf[BUFFER_SIZE];

       if (argc < 2)
       {
              usage(argv[0]);
              exit(1);
       }

       if ((clifd = socket(AF_INET,SOCK_STREAM,0)) < 0)
       {
              printf("create socket error!\n");
              exit(1);
       }

       srand(time(NULL));//initialize random generator
       bzero(&cliaddr,sizeof(cliaddr));
       cliaddr.sin_family = AF_INET;
       cliaddr.sin_port = htons(CLIENT_PORT);
       cliaddr.sin_addr.s_addr = htons(INADDR_ANY);

       bzero(&servaddr,sizeof(servaddr));
       servaddr.sin_family = AF_INET;
       inet_aton(argv[1],&servaddr.sin_addr);
       servaddr.sin_port = htons(SERVER_PORT);
       //servaddr.sin_addr.s_addr = htons(INADDR_ANY);

       if (bind(clifd,(struct sockaddr*)&cliaddr,sizeof(cliaddr))<0)
       {
              printf("bind to port %d failure!\n",CLIENT_PORT);
              exit(1);
       }

       if (connect(clifd,(struct sockaddr*)&servaddr, socklen) < 0)
       {
              printf("can't connect to %s!\n",argv[1]);
              exit(1);
       }

       length = recv(clifd,buf,BUFFER_SIZE,0);
       if (length < 0)
       {
              printf("error comes when recieve data from server %s!",argv[1]);
              exit(1);
       }
       printf("from server %s :\n\t%s ",argv[1],buf);

       close(clifd);
       return 0;
}