client.c

linux下学习socket的编程,使用tcp协议

# include <stdio.h>
# include <sys/types.h>
# include <sys/socket.h>
# include <netinet/in.h>
# include <netdb.h>
# define SERVER_PORT 5432
# define MAX_LINE 256
//struct socksddr_in
  // {
    //    short sin_family;      /*  AF_INET   */
      //  u_short  sin_port;
                  /*   16特端口号  网络字节顺序*/
       // struct in_addr, sin_addr;
              /* 32比特IP地址，网络字节顺序*/
       // char sin_zero[8];             /* 未用  */
 // }

int main(int argc,char * argv[])
{
  FILE *fp;
  struct hostent *hp;
  struct sockaddr_in sin;
  char *host;
  char buf[MAX_LINE];
  int s;
  int len;
 if(argc==2){
 host=argv[1];
}
  else {
    fprintf(stderr,"usage:simplex-talk host\n");
    exit(1);
  }
/* 将主机名翻译成对等实体的IP地址 */
hp=gethostbyname(host);
if(!hp) {
 fprintf(stderr,"simplex-talk:unknown host:%s\n",host);
 exit(1);   }
/*建立地址数据结构 */
bzero((char *)&sin,sizeof(sin));
sin.sin_family=AF_INET;
bcopy(hp->h_addr,(char *)&sin.sin_addr,hp->h_length);
sin.sin_port=htons(SERVER_PORT);
/*主动打开 */
if((s=socket(PF_INET,SOCK_STREAM,0))<0) {
    perror("simplex-talk:socket");
exit(1); }
if(connect(s, (struct sockaddr *)&sin,sizeof(sin)) <0  ) {
perror("simplex-talk:connect");
close(s);
exit(1); }
/* 主循:获得并发送文本行 */
while(fgets(buf,sizeof(buf),stdin)){
buf[MAX_LINE-1]='\0';
len=strlen(buf)+1;
send(s,buf,len,0); }
}