B. TCP Socket Programming in Unix Using C Programming

Socket Programming Server Example Program

/*ECHO SERVER USING TCP IN C*/
#include<netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include<stdio.h>
#include <arpa/inet.h>
#include <string.h>
#include<fcntl.h>

main() {
   int sd, cd;
   char buf[100] = "";
   struct sockaddr_in ser;
   sd = socket(AF_INET, SOCK_STREAM, 0);
   if (sd < 0)
      printf("SOCKET NOT CREATED\n");
   bzero(&ser, sizeof (struct sockaddr_in));
   ser.sin_family = AF_INET;
   ser.sin_port = htons(1012);
   inet_aton("172.16.29.78", &ser.sin_addr);
   int b = bind(sd, (struct sockaddr *) &ser, sizeof (ser));
   printf("BIND VALUE:%d\n", b);
   listen(sd, 5);
   for (;;) {
      cd = accept(sd, NULL, NULL);
      int pid = fork();
      if (pid == 0) {
         printf("accept value %d\n", cd);
         read(cd, buf, 100);
         printf("MESSAGE FROM CLIENT:%s\n", buf);
         write(cd, buf, strlen(buf));
         close(cd);
      }
   }
   close(sd);
}

Socket Programming Client Example Program

/*ECHO CLIENT USING TCP IN C*/

#include<netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include<stdio.h>
#include <arpa/inet.h>
#include <string.h>
#include<fcntl.h>

main() {
   int sd, cd;
   char buf[100] = "", buf1[100] = "";
   struct sockaddr_in ser;
   sd = socket(AF_INET, SOCK_STREAM, 0);
   if (sd < 0)
      printf("SOCKET NOT CREATED\n");
   bzero(&ser, sizeof (struct sockaddr_in));
   ser.sin_family = AF_INET;
   ser.sin_port = htons(1012);
   inet_aton("172.16.29.78", &ser.sin_addr);
   int c = connect(sd, (struct sockaddr *) &ser, sizeof (ser));
   printf("CONNET %d\n", c);
   if (c < 0)
      printf("CONNECTION FAILED\n");
   for (;;) {
      printf("ENTER THE MESSAGE");
      scanf("%s", buf);
      write(sd, buf, strlen(buf));
      read(sd, buf1, 100);
      printf("RECEIVED FROM SERVER%s\n", buf1);
   }
   close(sd);
   close(cd);
}

Sample Output for Server:

cc tserver.c -o tser
./tser
BIND VALUE:0
accept value 4
MESSAGE FROM CLIENT:Hello

Sample Output for Client:

cc tclient.c -o tcli
./tcli
CONNET 0
ENTER THE MESSAGE
Hello