// Thanks IBM
// http://www.ibm.com/developerworks/linux/tutorials/l-sock2/section5.html
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define BUFFSIZE 255
void Die(const char *mess)
{
perror(mess);
exit(1);
}
int main(int argc, char *argv[])
{
int sock;
struct sockaddr_in echoserver;
struct sockaddr_in echoclient;
char buffer[BUFFSIZE];
unsigned int clientlen, serverlen;
int received = 0;
if (argc != 2) {
fprintf(stderr, "USAGE: %s <port>\n", argv[0]);
exit(1);
}
/* Create the UDP socket */
if ((sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
Die("Failed to create socket");
}
/* Construct the server sockaddr_in structure */
memset(&echoserver, 0, sizeof(echoserver)); /* Clear struct */
echoserver.sin_family = AF_INET; /* Internet/IP */
echoserver.sin_addr.s_addr = htonl(INADDR_ANY); /* Any IP address */
echoserver.sin_port = htons(atoi(argv[1])); /* server port */
/* Bind the socket */
serverlen = sizeof(echoserver);
if (bind(sock, (struct sockaddr *) &echoserver, serverlen) < 0) {
Die("Failed to bind server socket");
}
/* Run until cancelled */
while (1) {
/* Receive a message from the client */
clientlen = sizeof(echoclient);
if ((received = recvfrom(sock,
buffer,
BUFFSIZE,
0,
(struct sockaddr *) &echoclient,
&clientlen)
) < 0) {
Die("Failed to receive message");
}
fprintf(stderr,
"Client connected: %s\n",
inet_ntoa(echoclient.sin_addr));
/* Send the message back to client */
if (sendto(sock,
buffer,
received,
0,
(struct sockaddr *) &echoclient,
sizeof(echoclient)
) != received) {
Die("Mismatch in number of echo'd bytes");
}
}
}
