client.c

先用makefile编译,连接后,client发字符到server端并返回该字符串,遇到a,e,i,o,u则加*号,如*a,收到fin字符串则结束客户端及服务器端程序.实现echo功能

/*
** client.c--a atream socket client demo
*/

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

#define PORT 3490 //the port client will be connecting to

#define MAXDATASIZE 100 //max number of bytes we can get at once

int main(int argc, char *argv[])
{
  int sockfd, numbytes;
  char buf[MAXDATASIZE];
  char sendbuf[MAXDATASIZE];
  struct hostent *he;
  struct sockaddr_in their_addr; //connector's address information
  
  if(argc!=3){
     fprintf(stderr, "usage: client hostname\n");
     exit(1);
   }

  if((he=gethostbyname(argv[1]))==NULL){ //get the host info
     perror("gethostbyname");
     exit(1);
   }

   if((sockfd=socket(AF_INET, SOCK_STREAM, 0))==-1){
      perror("socket");
      exit(1);
    }

   their_addr.sin_family=AF_INET; //host byte order
   their_addr.sin_port=htons(PORT); //short, network byte order
   their_addr.sin_addr=*((struct in_addr*)he->h_addr);
   memset(&(their_addr.sin_zero),'\0',8);  //zero the rest of the struct
   
   if (connect(sockfd, (struct sockaddr*)&their_addr, sizeof(struct sockaddr))==-1){
      perror("connect");
      exit(1);
    }

   printf("connection has been established with server. Type any message for server\n");
   
   for(;;){
      fgets(sendbuf, MAXDATASIZE, stdin);
      //scanf("%s",sendbuf);
      numbytes=sizeof(sendbuf);
      sendbuf[numbytes]='\0';
      if(numbytes == 0||strncmp(sendbuf,"fin",3) == 0){
         printf("fi*n\n");
         break;
      }
      else{
           if((numbytes=send(sockfd, sendbuf, sizeof(sendbuf),0))==-1){
              perror("send");
              close(sockfd);
              exit(1);
           }

           sendbuf[numbytes]='\0';
           printf("Sent: %s\n", sendbuf);
           
           if((numbytes=recv(sockfd, buf, 127, 0))==-1){
                perror("recv");
                exit(1);
           }
 
           buf[numbytes]='\0';
           
           printf("Received: %s\n",buf);
      }
     }
     close(sockfd);
     return 0;
}