Programming

/** server code **/

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

#define portno  6789

void error(char*);

void error(char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
     int serversocket;
     int newsockfd;
     int clilen;
     char buffer[4096];
     struct sockaddr_in serv_addr, cli_addr;
     int n;

     if( (serversocket = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
        error("ERROR opening socket");
     }

     bzero((char *) &serv_addr, sizeof(serv_addr));
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);

     if ( bind(serversocket, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0 )
     {
       error("ERROR on binding");
     }

     if( (listen(serversocket,5)) == - 1 ) {
       perror("Unable to connect\n");
       close(serversocket);
       exit(1);
     }

    while (1) {
       clilen = sizeof(cli_addr);
       if( (newsockfd = accept(serversocket,(struct sockaddr *) &cli_addr, &clilen)) < 0 )
       {
         error("ERROR on accept");
       }

       strcpy(buffer, "something");
       n = write(newsockfd, buffer, strlen(buffer));
       if (n < 0)
       {
         error("ERROR writing to socket");
       }
       close(newsockfd);
     }
     return 0;
}

/** client code **/

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

#define portno 6789 /* default port and host */
#define MAXDATASIZE 100 /* max number of bytes */

void error(char *msg)
{
perror(msg);
exit(0);
}

int main(int argc, char *argv[])
{
int serversocket, numbytes;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[MAXDATASIZE];
int rc;

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

if( ( server = gethostbyname("hostname")) == NULL ) {
perror("gethostbyname");
exit(1);
}

bzero((char*) &serv_addr, sizeof(serv_addr));
serv_addr.sin_family = AF_INET;

bcopy((char*)server->h_addr, (char*)&serv_addr.sin_addr.s_addr, server->h_length);
serv_addr.sin_port = htons(portno);

if( (rc = connect(serversocket, (struct sockaddr*)&serv_addr, sizeof(serv_addr))) == -1 ) {
perror("connect");
exit(1);
}

if ((numbytes=recv(serversocket, buffer, MAXDATASIZE-1, 0)) == -1) {
perror("recv");
exit(1);
}

buffer[numbytes + 1] = '\0';
printf("Received: %s\n",buffer);

close(serversocket);
return 0;
}