talker.c

#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#define PORT "4950"

#include "network.h"

int main(int argc, char const *argv[]) {
  int sockfd;
  struct addrinfo hints, *servinfo, *p;
  int rv;
  int numbytes;

  if (argc != 3) {
    fprintf(stdout, "usage: talker hostname message\n");
    exit(1);
  }

  memset(&hints, 0, sizeof(hints));
  hints.ai_family = AF_INET6;
  hints.ai_socktype = SOCK_DGRAM;

  if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
    return 1;
  }

  for (p = servinfo; p != NULL; p = p->ai_next) {
    if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) {
      perror("talker: socket");
      continue;
    }

    break;
  }

  if (p == NULL) {
    fprintf(stderr, "talker: failed to create socket\n");
    return 2;
  }

  if ((numbytes = sendto(sockfd, argv[2], strlen(argv[2]), 0, p->ai_addr,
                         p->ai_addrlen)) == -1) {
    perror("talker: sendto");
    exit(1);
  }

  freeaddrinfo(servinfo);

  printf("talker: sent %d bytes to %s\n", numbytes, argv[1]);
  close(sockfd);

  return 0;
}