UDP

//Server
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>

int main(void){
int sockfd;
struct sockaddr_in server_addr, client_addr;
char server_message[2000], client_message[2000];
int clientlen = sizeof(client_addr);

memset(server_message, '\0', sizeof(server_message));
memset(client_message, '\0', sizeof(client_message));
sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

if(sockfd < 0)
{
printf("Error while creating socket\n");
return -1;
}
else
{
printf("Socket created successfully\n");
}
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(7000);
server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
if(bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0)
{
printf("Couldn't bind to the port\n");
return -1;
}
else
{
printf("Done with binding\n");
printf("Listening for incoming messages...\n\n");
}
if (recvfrom(sockfd, client_message, sizeof(client_message), 0,
(struct sockaddr*)&client_addr, &clientlen) < 0)
{
printf("Couldn't receive\n");
return -1;
}
else
{
printf("Received message from IP: %s and port: %i\n",
inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
printf("Msg from client: %s\n", client_message);
printf("Enter Response\n");
gets(server_message);
}
if (sendto(sockfd, server_message, strlen(server_message), 0,
(struct sockaddr*)&client_addr, clientlen) < 0)
{
printf("Can't send\n");
return -1;
}
close(sockfd);

return 0;
}

//Client
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>

int main(void){
int sockfd;
struct sockaddr_in server_addr;
char server_message[2000], client_message[2000];
int serverlen = sizeof(server_addr);

memset(server_message, '\0', sizeof(server_message));
memset(client_message, '\0', sizeof(client_message));
sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

if(sockfd < 0)
{
printf("Error while creating socket\n");
return -1;
}
else
{
printf("Socket created successfully\n");
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(7000);
server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
printf("Enter message: ");
gets(client_message);
}

if(sendto(sockfd, client_message, strlen(client_message), 0,
(struct sockaddr*)&server_addr, serverlen) < 0){
printf("Unable to send message\n");
return -1;
}

if(recvfrom(sockfd, server_message, sizeof(server_message), 0,
(struct sockaddr*)&server_addr, &serverlen) < 0)
{
printf("Error while receiving server's msg\n");
return -1;
}
else
{
printf("Server's response: %s\n", server_message);
close(sockfd);
}
return 0;
}