rexecd.c

linux下常用的网络工具的代码

/*
 * Copyright (c) 1983, 1993
 *	The 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.
 * 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.
 */

#ifndef lint
static char copyright[] = "@(#) Copyright (c) 1983, 1993\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
static char sccsid[] = "@(#)rexecd.c	8.1 (Berkeley) 6/4/93";
#endif /* not lint */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/types.h>
#include <sys/param.h>
#include <sys/ioctl.h>
#ifdef HAVE_SYS_FILIO_H
#include <sys/filio.h>
#endif
#include <sys/socket.h>
#ifdef TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# ifdef HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif

#include <netinet/in.h>

#include <errno.h>
#include <netdb.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_CRYPT_H
# include <crypt.h>
#endif
#include <getopt.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_STDARG_H
#include <stdarg.h>
#else
#include <varargs.h>
#endif
#ifdef HAVE_SHADOW_H
# include <shadow.h>
#endif

void error (const char *fmt, ...);
void usage (void);

static const char *short_options = "hV";
static struct option long_options[] = {
  {"help", no_argument, 0, 'h'},
  {"version", no_argument, 0, 'V'},
  {0}
};

/*
 * remote execute server:
 *	username\0
 *	password\0
 *	command\0
 *	data
 */
/*ARGSUSED*/
int
main (int argc, char **argv)
{
  struct sockaddr_in from;
  int fromlen, sockfd = STDIN_FILENO;
  int c;

  while ((c = getopt_long (argc, argv, short_options, long_options, NULL))
	 != EOF)
    {
      switch (c)
	{
	case 'V':
	  printf ("rexecd (%s %s)\n", PACKAGE_NAME, PACKAGE_VERSION);
	  exit (0);

	case 'h':
	default:
	  usage ();
	  exit (0);
	}
    }

  fromlen = sizeof (from);
  if (getpeername (sockfd, (struct sockaddr *) &from, &fromlen) < 0)
    {
      fprintf (stderr, "rexecd: getpeername: %s\n", strerror (errno));
      exit (1);
    }
  doit (sockfd, &from);
  exit (0);
}

char username[20] = "USER=";
char logname[23] = "LOGNAME=";
char homedir[64] = "HOME=";
char shell[64] = "SHELL=";
char path[sizeof (PATH_DEFPATH) + sizeof ("PATH=")] = "PATH=";
char *envinit[] = { homedir, shell, path, username, logname, 0 };
extern char **environ;

#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
struct sockaddr_in asin = { sizeof (asin), AF_INET };
#else
struct sockaddr_in asin = { AF_INET };
#endif

char *getstr (const char *);

static char *
get_user_password (struct passwd *pwd)
{
  char *pw_text = pwd->pw_passwd;
#ifdef HAVE_SHADOW_H
  struct spwd *spwd = getspnam (pwd->pw_name);
  if (spwd)
    pw_text = spwd->sp_pwdp;
#endif
  return pw_text;
}

int
doit (int f, struct sockaddr_in *fromp)
{
  char *cmdbuf, *cp, *namep;
  char *user, *pass, *pw_password;
  struct passwd *pwd;
  int s;
  u_short port;
  int pv[2], pid, cc;
  fd_set readfrom, ready;
  char buf[BUFSIZ], sig;
  int one = 1;

  signal (SIGINT, SIG_DFL);
  signal (SIGQUIT, SIG_DFL);
  signal (SIGTERM, SIG_DFL);
#ifdef DEBUG
  {
    int t = open (_PATH_TTY, O_RDWR);
    if (t >= 0)
      {
	ioctl (t, TIOCNOTTY, (char *) 0);
	close (t);
      }
  }
#endif
  if (f != STDIN_FILENO)
    {
      dup2 (f, STDIN_FILENO);
      dup2 (f, STDOUT_FILENO);
      dup2 (f, STDERR_FILENO);
    }

  alarm (60);
  port = 0;
  for (;;)
    {
      char c;
      if (read (f, &c, 1) != 1)
	exit (1);
      if (c == 0)
	break;
      port = port * 10 + c - '0';
    }
  alarm (0);
  if (port != 0)
    {
      s = socket (AF_INET, SOCK_STREAM, 0);
      if (s < 0)
	exit (1);
      if (bind (s, (struct sockaddr *) &asin, sizeof (asin)) < 0)
	exit (1);
      alarm (60);
      fromp->sin_port = htons (port);
      if (connect (s, (struct sockaddr *) fromp, sizeof (*fromp)) < 0)
	exit (1);
      alarm (0);
    }

  user = getstr ("username");
  pass = getstr ("password");
  cmdbuf = getstr ("command");

  setpwent ();
  pwd = getpwnam (user);
  if (pwd == NULL)
    {
      error ("Login incorrect.\n");
      exit (1);
    }
  endpwent ();
  pw_password = get_user_password (pwd);
  if (*pw_password != '\0')
    {
      namep = crypt (pass, pw_password);
      if (strcmp (namep, pw_password))
	{
	  error ("Password incorrect.\n");
	  exit (1);
	}
    }
  write (STDERR_FILENO, "\0", 1);
  if (port)
    {
      pipe (pv);
      pid = fork ();
      if (pid == -1)
	{
	  error ("Try again.\n");
	  exit (1);
	}
      if (pid)
	{
	  close (STDIN_FILENO);
	  close (STDOUT_FILENO);
	  close (STDERR_FILENO);
	  close (f);
	  close (pv[1]);
	  FD_ZERO (&readfrom);
	  FD_SET (s, &readfrom);
	  FD_SET (pv[0], &readfrom);
	  ioctl (pv[1], FIONBIO, (char *) &one);
	  /* should set s nbio! */
	  do
	    {
	      int maxfd = s;
	      ready = readfrom;
	      if (pv[0] > maxfd)
		maxfd = pv[0];
	      select (maxfd + 1, (fd_set *) & ready,
		      (fd_set *) NULL, (fd_set *) NULL,
		      (struct timeval *) NULL);
	      if (FD_ISSET (s, &ready))
		{
		  if (read (s, &sig, 1) <= 0)
		    FD_CLR (s, &readfrom);
		  else
		    killpg (pid, sig);
		}
	      if (FD_ISSET (pv[0], &ready))
		{
		  cc = read (pv[0], buf, sizeof (buf));
		  if (cc <= 0)
		    {
		      shutdown (s, 1 + 1);
		      FD_CLR (pv[0], &readfrom);
		    }
		  else
		    write (s, buf, cc);
		}
	    }
	  while (FD_ISSET (pv[0], &readfrom) || FD_ISSET (s, &readfrom));
	  exit (0);
	}
      setpgid (0, getpid ());
      close (s);
      close (pv[0]);
      dup2 (pv[1], STDERR_FILENO);
    }
  if (*pwd->pw_shell == '\0')
    pwd->pw_shell = PATH_BSHELL;
  if (f > 2)
    close (f);
  setegid ((gid_t) pwd->pw_gid);
  setgid ((gid_t) pwd->pw_gid);
#ifdef HAVE_INITGROUPS
  initgroups (pwd->pw_name, pwd->pw_gid);
#endif
  setuid ((uid_t) pwd->pw_uid);
  if (chdir (pwd->pw_dir) < 0)
    {
      error ("No remote directory.\n");
      exit (1);
    }
  strcat (path, PATH_DEFPATH);
  environ = envinit;
  strncat (homedir, pwd->pw_dir, sizeof (homedir) - 6);
  strncat (shell, pwd->pw_shell, sizeof (shell) - 7);
  strncat (username, pwd->pw_name, sizeof (username) - 6);
  cp = strrchr (pwd->pw_shell, '/');
  if (cp)
    cp++;
  else
    cp = pwd->pw_shell;
  execl (pwd->pw_shell, cp, "-c", cmdbuf, 0);
  perror (pwd->pw_shell);
  exit (1);
}

/*VARARGS1*/
void
error (const char *fmt, ...)
{
  va_list ap;
  int len;
  char buf[BUFSIZ];
#if defined(HAVE_STDARG_H) && defined(__STDC__) && __STDC__
  va_start (ap, fmt);
#else
  va_start (ap);
#endif
  buf[0] = 1;
  snprintf (buf + 1, sizeof buf - 1, fmt, ap);
  write (STDERR_FILENO, buf, strlen (buf));
}

char *
getstr (const char *err)
{
  size_t buf_len = 100;
  char *buf = malloc (buf_len), *end = buf;

  if (!buf)
    {
      error ("Out of space reading %s\n", err);
      exit (1);
    }

  do
    {
      /* Oh this is efficient, oh yes.  [But what can be done?] */
      int rd = read (STDIN_FILENO, end, 1);
      if (rd <= 0)
	{
	  if (rd == 0)
	    error ("EOF reading %s\n", err);
	  else
	    perror (err);
	  exit (1);
	}

      end += rd;
      if ((buf + buf_len - end) < (buf_len >> 3))
	{
	  /* Not very much room left in our buffer, grow it. */
	  size_t end_offs = end - buf;
	  buf_len += buf_len;
	  buf = realloc (buf, buf_len);
	  if (!buf)
	    {
	      error ("Out of space reading %s\n", err);
	      exit (1);
	    }
	  end = buf + end_offs;
	}
    }
  while (*(end - 1));

  return buf;
}


static const char usage_str[] =
  "Usage: rexecd [OPTIONS...]\n"
  "\n"
  "Options are:\n"
  "       --help              Display usage instructions\n"
  "       --version           Display program version\n";

void
usage (void)
{
  printf ("%s\n" "Send bug reports to <%s>\n", usage_str, PACKAGE_BUGREPORT);
}