11-12 IPv4射影アドレスを利用したサーバプログラム

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

int
main()
{
  struct addrinfo hints;
  struct addrinfo *res = NULL;
  int sock0, sock;
  struct sockaddr_storage ss;
  socklen_t sslen;
  char buf[1024];
  int n;

  memset(&hints, 0, sizeof(hints));
  hints.ai_family = AF_INET6;
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_flags = AI_PASSIVE;

  n = getaddrinfo(NULL, "12345", &hints, &res);
  if (n != 0) {
    printf("getaddrinfo : %s\n", gai_strerror(n));
    return 1;
  }

  sock0 = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
  if (sock0 < 0) {
    perror("socket");
    return 1;
  }

  if (bind(sock0, res->ai_addr, res->ai_addrlen) != 0) {
    perror("bind");
    return 1;
  }

  if (listen(sock0, 5) != 0) {
    perror("listen");
    return 1;
  }

  for (;;) {
    sslen = sizeof(ss);
    sock = accept(sock0, (struct sockaddr *)&ss, &sslen);
    if (sock < 0) {
      perror("accept");
      return 1;
    }

    n = getnameinfo((struct sockaddr *)&ss, sslen,
                  buf, sizeof(buf), NULL, 0, NI_NUMERICHOST);
    if (n != 0) {
      printf("getnameinfo : %s\n", gai_strerror(n));
      return 1;
    }

    printf("connection from [%s]\n", buf);

    n = read(sock, buf, sizeof(buf));

    n = write(sock, buf, n);

    close(sock);
  }

  close(sock0);

  return 0;
}

拙著「Linuxネットワークプログラミング」の紹介