Linux下C编程：socket实例

客户端：

#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;
}

服务器端：

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

#define  SERVER_PORT 20000  //  define the defualt connect port id
#define  LENGTH_OF_LISTEN_QUEUE 10  // length of listen queue in server
#define  BUFFER_SIZE 255
#define  WELCOME_MESSAGE "welcome to connect the server. "      

int main(int argc, char** argv)
{
       int  servfd,clifd;
       struct  sockaddr_in servaddr,cliaddr;     

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

       bzero( & servaddr, sizeof (servaddr));     

       servaddr.sin_family  =  AF_INET;
       servaddr.sin_port  =  htons(SERVER_PORT);
       servaddr.sin_addr.s_addr  =  htons(INADDR_ANY);     

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

        if  (listen(servfd,LENGTH_OF_LISTEN_QUEUE)  <   0 )
         {
              printf( " call listen failure!\n " );
              exit( 1 );
       }

        while  ( 1 )
         { // server loop will nerver exit unless any body kill the process      

              char  buf[BUFFER_SIZE];
              long  timestamp;
              socklen_t length  =   sizeof (cliaddr);
              clifd  =  accept(servfd,( struct  sockaddr * ) & cliaddr, & length);     

               if  (clifd  <   0 )
                {
                     printf( " error comes when call accept!\n " );
                     break ;
              }

              strcpy(buf,WELCOME_MESSAGE);

               // inet_ntop(INET_ADDRSTRLEN,cliaddr.sin_addr,buf,BUFFER_SIZE);

              printf( " from client,IP:%s,Port:%d\n " ,inet_ntoa(cliaddr.sin_addr),ntohs(cliaddr.sin_port));

              timestamp  =  time(NULL);

              strcat(buf, " timestamp in server: " );
              strcat(buf,ctime( & timestamp));

              send(clifd,buf,BUFFER_SIZE, 0 ); 

              close(clifd);                

       } // exit      

       close(servfd);     

        return   0 ;
}

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