Socket vježba (UDP)

talker.c

/*
** talker.c -- a datagram "client" 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>
#include <netdb.h>
#define MYPORT 4950 // the port users will be connecting to
int main(int argc, char *argv[]){
	int sockfd;
	struct sockaddr_in their_addr; // connector's address information
	struct hostent *he;
	int numbytes;
	if (argc != 3) {
		fprintf(stderr,"usage: talker hostname message\n");
		exit(1);
	}
	if ((he=gethostbyname(argv[1])) == NULL) { // get the host info
		perror("gethostbyname");
		exit(1);
	}
	if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
		perror("socket");
		exit(1);
	}
	their_addr.sin_family = AF_INET; // host byte order
	their_addr.sin_port = htons(MYPORT); // short, network byte order
	their_addr.sin_addr = *((struct in_addr *)he->h_addr);
	memset(&(their_addr.sin_zero), '\0', 8); // zero the rest of the struct
	if ((numbytes=sendto(sockfd, argv[2], strlen(argv[2]), 0,
		(struct sockaddr *)&their_addr, sizeof(struct sockaddr))) == -1) {
		perror("sendto");
		exit(1);
	}
	printf("sent %d bytes to %s\n", numbytes,
	inet_ntoa(their_addr.sin_addr));
	close(sockfd);
	return 0;
}