Skip to content

Instantly share code, notes, and snippets.

@Batname
Created April 26, 2018 06:24
Show Gist options
  • Save Batname/f28ee1e935de847a135e9b0ff5d21c40 to your computer and use it in GitHub Desktop.
Save Batname/f28ee1e935de847a135e9b0ff5d21c40 to your computer and use it in GitHub Desktop.
/*
Simple UDP Server
*/
#include<stdio.h>
#include<winsock2.h>
#pragma warning(disable:4996)
#pragma comment(lib,"ws2_32.lib") //Winsock Library
#define BUFLEN 512 //Max length of buffer
#define PORT 9999 //The port on which to listen for incoming data
int main()
{
SOCKET s;
struct sockaddr_in server, si_other;
int slen, recv_len;
char buf[BUFLEN];
WSADATA wsa;
slen = sizeof(si_other);
//Initialise winsock
printf("\nInitialising Winsock...");
if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0)
{
printf("Failed. Error Code : %d", WSAGetLastError());
exit(EXIT_FAILURE);
}
printf("Initialised.\n");
//Create a socket
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == INVALID_SOCKET)
{
printf("Could not create socket : %d", WSAGetLastError());
}
printf("Socket created.\n");
//Prepare the sockaddr_in structure
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons(PORT);
//Bind
if (bind(s, (struct sockaddr *)&server, sizeof(server)) == SOCKET_ERROR)
{
printf("Bind failed with error code : %d", WSAGetLastError());
exit(EXIT_FAILURE);
}
puts("Bind done");
//keep listening for data
while (1)
{
printf("Waiting for data...");
fflush(stdout);
//clear the buffer by filling null, it might have previously received data
memset(buf, '\0', BUFLEN);
//try to receive some data, this is a blocking call
if ((recv_len = recvfrom(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, &slen)) == SOCKET_ERROR)
{
printf("recvfrom() failed with error code : %d", WSAGetLastError());
exit(EXIT_FAILURE);
}
//print details of the client/peer and the data received
printf("Received packet from %s:%d\n", inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port));
printf("Data: %s\n", buf);
//now reply the client with the same data
if (sendto(s, buf, recv_len, 0, (struct sockaddr*) &si_other, slen) == SOCKET_ERROR)
{
printf("sendto() failed with error code : %d", WSAGetLastError());
exit(EXIT_FAILURE);
}
}
closesocket(s);
WSACleanup();
return 0;
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment