Socket vježba (UDP)

listener.c

/*
** listener.c -- a datagram sockets "server" demo
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define MYPORT 4950 // the port users will be connecting to
#define MAXBUFLEN 100
int main(void) {
	int sockfd;
	struct sockaddr_in my_addr; // my address information
	struct sockaddr_in their_addr; // connector's address information
	int addr_len, numbytes;
	char buf[MAXBUFLEN];
	if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
		perror("socket");
		exit(1);
	}
	my_addr.sin_family = AF_INET; // host byte order
	my_addr.sin_port = htons(MYPORT); // short, network byte order
	my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
	memset(&(my_addr.sin_zero), '\0', 8); // zero the rest of the struct
	if (bind(sockfd, (struct sockaddr *)&my_addr,
		sizeof(struct sockaddr)) == -1) {
		perror("bind");
		exit(1);
	}
	addr_len = sizeof(struct sockaddr);
	if ((numbytes=recvfrom(sockfd,buf, MAXBUFLEN-1, 0,
		(struct sockaddr *)&their_addr, &addr_len)) == -1) {
		perror("recvfrom");
		exit(1);
	}
	printf("got packet from %s\n",inet_ntoa(their_addr.sin_addr));
	printf("packet is %d bytes long\n",numbytes);
	buf[numbytes] = '\0';
	printf("packet contains \"%s\"\n",buf);
	close(sockfd);
	return 0;
}