UDP Echo Client Server Program in UNIX

SERVER.C

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

int main()
{
        int sock;
        int addr_len, bytes_read;
        char recv_data[1024];
        struct sockaddr_in server_addr , client_addr;
         if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
         perror("Socket");
         exit(1);
  }

        server_addr.sin_family = AF_INET;
        server_addr.sin_port = htons(4200);
        server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
        bzero(&(server_addr.sin_zero),8);
        if (bind(sock,(struct sockaddr *)&server_addr,
        sizeof(struct sockaddr)) == -1)
        {
            perror("Bind");
            exit(1);
        }
        addr_len = sizeof(struct sockaddr);
        printf("\nUDPServer Waiting for client on port 5500");
        fflush(stdout);
        while (1)
        {

          bytes_read = recvfrom(sock,recv_data,1024,0,
                            (struct sockaddr *)&client_addr, &addr_len);
recv_data[bytes_read] = '\0';
printf("\n(%s , %d) said : ",inet_ntoa(client_addr.sin_addr),
                                       ntohs(client_addr.sin_port));
          printf("%s", recv_data);
          fflush(stdout);
        }
        return 0;
}

 CLIENT.C

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

int main()
{
int sock,addr_len,bytes_read;
struct sockaddr_in server_addr,client_addr;
struct hostent *host;
char send_data[1024],recv_data[1024];
host= (struct hostent *) gethostbyname((char *)"127.0.0.1");
if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
{
perror("socket");
exit(1);
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(5100);
server_addr.sin_addr = *((struct in_addr *)host->h_addr);
bzero(&(server_addr.sin_zero),8);
addr_len=sizeof(struct sockaddr);
   while (1)
   {
    printf("Type Something (q or Q to quit):");
    fgets(send_data,sizeof(send_data),stdin);
    if ((strcmp(send_data , "q") == 0) || strcmp(send_data , "Q") == 0)
       break;
    else
      {
       sendto(sock, send_data, strlen(send_data), 0,
              (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
      }
       bytes_read = recvfrom(sock,recv_data,1024,0,
                  (struct sockaddr *)&server_addr, &addr_len);
      recv_data[bytes_read] = '\0';
      printf("\n(%s , %d) said : ",inet_ntoa(server_addr.sin_addr),
                             ntohs(server_addr.sin_port));
      printf("%s", recv_data);
      fflush(stdout);
   }
return 0;
}