2-23 ファイル送信側

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <fcntl.h>

int
main(int argc, char *argv[])
{
  char *service = "12345";
  struct addrinfo hints, *res0, *res;
  int err;
  int sock;
  int fd;
  char buf[65536];
  int n, ret;

  if (argc != 3) {
    fprintf(stderr, "Usage : %s hostname filename\n", argv[0]);
    return 1;
  }

  fd = open(argv[2], O_RDONLY);
  if (fd < 0) {
    perror("open");
    return 1;
  }

  memset(&hints, 0, sizeof(hints));
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_family = PF_UNSPEC;
  if ((err = getaddrinfo(argv[1], service, &hints, &res0)) != 0) {
    printf("error %d : %s\n", err, gai_strerror(err));
    return 1;
  }

  for (res=res0; res!=NULL; res=res->ai_next) {
    sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
    if (sock < 0) {
      continue;
    }

    if (connect(sock, res->ai_addr, res->ai_addrlen) != 0) {
      close(sock);
      continue;
    }

    break;
  }

  freeaddrinfo(res0);
  if (res == NULL) {
    /* 有効な接続ができなかった */
    printf("failed\n");
    return 1;
   }

  while ((n = read(fd, buf, sizeof(buf))) > 0) {
    ret = write(sock, buf, n);
    if (ret < 1) {
      perror("write");
      break;
    }
  }

  close(sock);

  return 0;
}

拙著「Linuxネットワークプログラミング」の紹介