/*
 *    portmsg - generate a message on a port, then close connection
 *
 *      Usage:  portmsg file port
 *
 *              When a telnet client connects to the specified port, the
 *              text from the file will be echoed to the user.  After a
 *              short delay the connection will close.
 *
 * Derived from ftpd by Klaas @ {RUD, LPSwat}, original ftpd copyright
 * message follows:
 *
 * Copyright (c) 1985, 1988, 1990 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This version extensively modified by Javelin (Alan Schwartz)
 * to conform to PennMUSH autoconfiguration standards.
 */

/* If you have multiple IP addresses and want to bind to only one,
 * uncomment this:
 */
/*#define SINGLE_IP_ADDR "your.address.goes.here" */

#include "config.h"
#include <stdio.h>
#ifdef I_UNISTD
#include <unistd.h>
#endif
#include <limits.h>
#ifdef I_SYS_TYPES
#include <sys/types.h>
#endif
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <errno.h>
#ifdef I_SYS_ERRNO
#include <sys/errno.h>
#endif
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/param.h>
#include <signal.h>
#ifdef I_SYS_WAIT
#include <sys/wait.h>
#endif
#include <fcntl.h>

#include "conf.h"
#include "externs.h"
#include "mymalloc.h"
#include "confmagic.h"

/* What htons expects */
typedef unsigned short Port_t;

#ifdef HAS_WAITPID
#define WAIT_TYPE int
#else
#ifdef UNION_WAIT
#define WAIT_TYPE union wait
#else
#define WAIT_TYPE int
#endif
#endif

static Signal_t wait_on_child(int sig);
static Signal_t lostconn(int sig);
static int how_many_fds(void);

static Signal_t
wait_on_child(int sig __attribute__ ((__unused__)))
{
  WAIT_TYPE status;

#ifdef HAS_WAITPID
  while (waitpid(-1, &status, WNOHANG) > 0) ;
#else
  while (wait3(&status, WNOHANG, 0) > 0) ;
#endif

#ifndef SIGNALS_KEPT
  signal(SIGCLD, (Sigfunc) wait_on_child);
#endif
#ifndef VOIDSIG
  return 0;
#endif
}

Signal_t
lostconn(int sig __attribute__ ((__unused__)))
{
  exit(1);
}

int
main(int argc, char **argv)
{
  int msgfd, fd, n;
  struct stat statBuf;
  Port_t port;
  char *msg;
  int sockfd, newsockfd;
  int addrlen;
  int opt;
  struct sockaddr_in tcp_srv_addr;
  struct sockaddr_in their_addr;
  int num_fds;

  if (argc != 3) {
    fprintf(stderr, "Usage: portmsg file port\n");
    exit(1);
  }
  port = atoi(argv[2]);
  if (port == 0) {
    fprintf(stderr, "error: bad port number [%s]\n", argv[2]);
    exit(1);
  }
  if ((msgfd = open(argv[1], O_RDONLY)) < 0) {
    fprintf(stderr, "error: cannot open message file [%s]\n", argv[1]);
    exit(1);
  }
  /* read the message */
  fstat(msgfd, &statBuf);
  if (statBuf.st_size <= 0) {
    fprintf(stderr, "error: message file [%s] is empty\n", argv[1]);
    exit(1);
  }
  msg = (char *) malloc(statBuf.st_size);
  if (read(msgfd, msg, statBuf.st_size) != statBuf.st_size) {
    fprintf(stderr, "error: cannot read message file [%s]\n", argv[1]);
    exit(1);
  }
  num_fds = how_many_fds();

  /* become a daemon */
  switch (fork()) {
  case -1:
    fprintf(stderr, "error: can't fork\n");
    exit(1);
  case 0:
    break;
  default:
    exit(0);
  }
#ifdef HAS_SETPGRP
#ifdef USE_BSD_SETPGRP
  if (setpgrp(0, getpid()) == -1) {
#else
  if (setpgrp() == -1) {
#endif
    fprintf(stderr, "error: can't change process group\n");
    exit(1);
  }
#endif

#ifdef USE_TIOCNOTTY
  if ((fd = open("/dev/tty", O_RDWR)) >= 0) {
    ioctl(fd, TIOCNOTTY, NULL);
    close(fd);
  }
#endif

  signal(SIGCLD, (void *) wait_on_child);
  memset((char *) &tcp_srv_addr, 0, sizeof(tcp_srv_addr));
  tcp_srv_addr.sin_family = AF_INET;
#ifdef SINGLE_IP_ADDR
  tcp_srv_addr.sin_addr.s_addr = inet_addr(MUSH_IP_ADDR);
#else
  tcp_srv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
#endif
  tcp_srv_addr.sin_port = htons(port);

  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    fprintf(stderr, "can't create stream socket\n");
    exit(-1);
  }
  opt = 1;
  if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
		 (char *) &opt, sizeof(opt)) < 0) {
    perror("setsockopt");
    exit(1);
  }
  if (bind(sockfd, (struct sockaddr *) &tcp_srv_addr, sizeof(tcp_srv_addr)) < 0) {
    fprintf(stderr, "can't bind local address\n");
    exit(-1);
  }
  listen(sockfd, 5);

main_again:
  addrlen = sizeof(their_addr);
  newsockfd = accept(sockfd, (struct sockaddr *) &their_addr, &addrlen);
  if (newsockfd < 0) {
    if (errno == EINTR)
      goto main_again;
    fprintf(stderr, "accept error\n");
    exit(-1);
  }
  switch (fork()) {
  case -1:
    fprintf(stderr, "server can't fork\n");
    exit(-1);
  case 0:
    dup2(newsockfd, 0);
    dup2(newsockfd, 1);
    for (n = 3; n < num_fds; n++)
      close(n);
    break;
  default:
    close(newsockfd);
    goto main_again;
  }

  /* daemon child arrives here */
  signal(SIGPIPE, lostconn);
  signal(SIGCLD, SIG_IGN);

  fprintf(stdout, msg);
  fflush(stdout);
  sleep(5);
  exit(0);
}

static int
how_many_fds(void)
{
  /* Determine how many open file descriptors we're allowed
   * In order, we'll try:
   * 0. OPEN_MAX constant - POSIX.1 limits.h
   * 1. sysconf(_SC_OPEN_MAX) - POSIX.1
   * 2. getdtablesize - BSD
   * 3. NOFILE - in some sys/param.h
   * 4. _NFILE - in some stdio.h
   */
#ifdef OPEN_MAX
  static int open_max = OPEN_MAX;
#else
  static int open_max = 0;
#endif

  if (open_max)
    return open_max;

#ifdef HAS_SYSCONF
  errno = 0;
  if ((open_max = sysconf(_SC_OPEN_MAX)) < 0) {
    if (errno == 0)		/* Value was indeterminate */
      open_max = 0;
  }
  if (open_max)
    return open_max;
#endif
  /* Caching getdtablesize is dangerous, since it's affected by
   * getrlimit, so we don't.
   */
  open_max = 0;
  return getdtablesize();
}