UDP Client-Server Chat Session

SERVER:

#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#define BUFLEN 512
#define PORT 9930

void err(char *str)
{
    perror(str);
    exit(1);
}

int main(void)
{
    struct sockaddr_in my_addr, cli_addr;
    int sockfd, i;
    socklen_t slen=sizeof(cli_addr);
    char buf[BUFLEN];

    if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1)
      err("socket");
    else
      printf("Server : Socket() successful\n");

    bzero(&my_addr, sizeof(my_addr));
    my_addr.sin_family = AF_INET;
    my_addr.sin_port = htons(PORT);
    my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
   
    if (bind(sockfd, (struct sockaddr* ) &my_addr, sizeof(my_addr))==-1)
      err("bind");
    else
      printf("Server : bind() successful\n");

    while(1)
    {
        if (recvfrom(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&cli_addr, &slen)==-1)
            err("recvfrom()");
        printf("Received packet from %s:%d\nData: %s\n\n",
               inet_ntoa(cli_addr.sin_addr), ntohs(cli_addr.sin_port), buf);
    }

    close(sockfd);
    return 0;
}


CLIENT:

#include <arpa/inet.h>
#include <netinet/in.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#define BUFLEN 512
#define PORT 9930

void err(char *s)
{
    perror(s);
    exit(1);
}

int main(int argc, char** argv)
{
    struct sockaddr_in serv_addr;
    int sockfd, i, slen=sizeof(serv_addr);
    char buf[BUFLEN];

    if(argc != 2)
    {
      printf("Usage : %s <Server-IP>\n",argv[0]);
      exit(0);
    }

    if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP))==-1)
        err("socket");

    bzero(&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    if (inet_aton(argv[1], &serv_addr.sin_addr)==0)
    {
        fprintf(stderr, "inet_aton() failed\n");
        exit(1);
    }

    while(1)
    {
        printf("\nEnter data to send(Type exit and press enter to exit) : ");
        scanf("%[^\n]",buf);
        getchar();
        if(strcmp(buf,"exit") == 0)
          exit(0);

        if (sendto(sockfd, buf, BUFLEN, 0, (struct sockaddr*)&serv_addr, slen)==-1)
            err("sendto()");
    }

    close(sockfd);
    return 0;
}


HOW TO RUN:
1: open terminal
2: gcc  server.c
3: ./a.out

4: open another terminal
5: gcc client.c
6: ./a.out <server-ip> (check the ip of the machine and put here)

OUTPUT:
SERVER SIDE
$ ./a.out
Server : Socket() successful
Server : bind() successful
Received packet from 192.168.0.3:37555
Data: hi

Received packet from 192.168.0.3:37555
Data: hello

Received packet from 192.168.0.3:37555
Data: i m client

CLIENT SIDE
$ ./a.out 192.168.0.3
Enter data to send(Type exit and press enter to exit) : hi

Enter data to send(Type exit and press enter to exit) : hello

Enter data to send(Type exit and press enter to exit) : i m client