ftpd.c

linux下ftpd服务器端的源码实现

/* - Ftp Server
 * Copyright (c) 1985, 1988, 1990, 1992, 1993, 1994, 2002
 *	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.
 */

#if 0
static char sccsid[] = "@(#)ftpd.c	8.5 (Berkeley) 4/28/95";
#endif

/*
 * FTP server.
 */

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

#if !defined (__GNUC__) && defined (_AIX)
#pragma alloca
#endif
#ifndef alloca /* Make alloca work the best possible way.  */
# ifdef __GNUC__
#  define alloca __builtin_alloca
# else /* not __GNUC__ */
#  if HAVE_ALLOCA_H
#   include <alloca.h>
#  else /* not __GNUC__ or HAVE_ALLOCA_H */
#    ifndef _AIX /* Already did AIX, up at the top.  */
       char *alloca ();
#    endif /* not _AIX */
#  endif /* not HAVE_ALLOCA_H */
# endif /* not __GNUC__ */
#endif /* not alloca */

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_WAIT_H
#  include <sys/wait.h>
#endif

#include <netinet/in.h>
#ifdef HAVE_NETINET_IN_SYSTM_H
#  include <netinet/in_systm.h>
#endif
#ifdef HAVE_NETINET_IP_H
#  include <netinet/ip.h>
#endif

#define	FTP_NAMES
#include <arpa/ftp.h>
#include <arpa/inet.h>
#include <arpa/telnet.h>

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <limits.h>
#include <netdb.h>
#include <setjmp.h>
#include <signal.h>
#include <grp.h>
#if defined(HAVE_STDARG_H) && defined(__STDC__) && __STDC__
#  include <stdarg.h>
#else
#  include <varargs.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.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 <unistd.h>
#ifdef HAVE_MMAP
#include <sys/mman.h>
#endif
/* Include glob.h last, because it may define "const" which breaks
   system headers on some platforms. */
#include <glob.h>

#include <libinetutils.h>
#include "extern.h"

#ifndef LINE_MAX
# define LINE_MAX 2048
#endif

#ifndef LOG_FTP
# define LOG_FTP LOG_DAEMON	/* Use generic facility.  */
#endif

#ifndef MAP_FAILED
# define MAP_FAILED (void*)-1
#endif

#if !HAVE_DECL_FCLOSE
/* Some systems don't declare fclose in <stdio.h>, so do it ourselves.  */
extern int fclose (FILE *);
#endif

char *program_name;

/* Exported to ftpcmd.h.  */
struct	sockaddr_in data_dest; /* Data port.  */
struct	sockaddr_in his_addr;  /* Peer address.  */
int	logging;               /* Enable log to syslog.  */
int	type = TYPE_A;         /* Default TYPE_A.  */
int	form = FORM_N;                  /* Default FORM_N.  */
int	debug;                 /* Enable debug mode if 1.  */
int	timeout = 900;         /* Timeout after 15 minutes of inactivity.  */
int	maxtimeout = 7200;     /* Don't allow idle time to be set
				  beyond 2 hours.  */
int	pdata = -1;            /* For passive mode.  */
char	*hostname;             /* Who we are.  */
int	usedefault = 1;	       /* For data transfers.  */
char	tmpline[7];            /* Temp buffer use in OOB.  */

/* Requester credentials.  */
struct credentials cred;

static struct  sockaddr_in ctrl_addr;    /* Control address.  */
static struct  sockaddr_in data_source;  /* Port address.  */
static struct  sockaddr_in pasv_addr;    /* Pasv address.  */

static int      data = -1;       /* Port data connection socket.  */
static jmp_buf  urgcatch;
static int      stru = STRU_F;     /* Avoid C keyword.  */
static int      stru_mode = MODE_S;/* Default STRU mode stru_mode = MODE_S.  */
static int      anon_only;       /* Allow only anonymous login.  */
static int      no_version;      /* Don't print version to client.  */
static int      daemon_mode;     /* Start in daemon mode.  */
static off_t    file_size;
static off_t    byte_count;
static sig_atomic_t transflag;   /* Flag where in a middle of transfer.  */
static const char *pid_file = PATH_FTPDPID;
#if !defined(CMASK) || CMASK == 0
#undef CMASK
#define CMASK 027
#endif
static int  defumask = CMASK;    /* Default umask value.  */
static int login_attempts;       /* Number of failed login attempts.  */
static int askpasswd;		 /* Had user command, ask for passwd.  */
static char curname[10];	 /* Current USER name.  */
static char ttyline[20];         /* Line to log in utmp.  */


#define NUM_SIMUL_OFF_TO_STRS 4

/* Returns a string with the decimal representation of the off_t OFF, taking
   into account that off_t might be longer than a long.  The return value is
   a pointer to a static buffer, but a return value will only be reused every
   NUM_SIMUL_OFF_TO_STRS calls, to allow multiple off_t's to be conveniently
   printed with a single printf statement.  */
static char *
off_to_str (off_t off)
{
  static char bufs[NUM_SIMUL_OFF_TO_STRS][80];
  static char (*next_buf)[80] = bufs;

  if (next_buf >= (bufs+NUM_SIMUL_OFF_TO_STRS))
    next_buf = bufs;

  if (sizeof (off) > sizeof (long))
    sprintf (*next_buf, "%qd", off);
  else if (sizeof (off) == sizeof (long))
    sprintf (*next_buf, "%ld", off);
  else
    sprintf (*next_buf, "%d", off);

  return *next_buf++;
}

/*
 * Timeout intervals for retrying connections
 * to hosts that don't accept PORT cmds.  This
 * is a kludge, but given the problems with TCP...
 */
#define	SWAITMAX	90	/* wait at most 90 seconds */
#define	SWAITINT	5	/* interval between retries */

static int swaitmax = SWAITMAX;
static int swaitint = SWAITINT;

#ifdef HAVE_SETPROCTITLE
char	proctitle[LINE_MAX];	/* initial part of title */
#endif /* SETPROCTITLE */

#define LOGCMD(cmd, file) \
	if (logging > 1) \
	    syslog(LOG_INFO,"%s %s%s", cmd, \
		*(file) == '/' ? "" : curdir(), file);
#define LOGCMD2(cmd, file1, file2) \
	 if (logging > 1) \
	    syslog(LOG_INFO,"%s %s%s %s%s", cmd, \
		*(file1) == '/' ? "" : curdir(), file1, \
		*(file2) == '/' ? "" : curdir(), file2);
#define LOGBYTES(cmd, file, cnt) \
	if (logging > 1) { \
		if (cnt == (off_t)-1) \
		    syslog(LOG_INFO,"%s %s%s", cmd, \
			*(file) == '/' ? "" : curdir(), file); \
		else \
		    syslog(LOG_INFO, "%s %s%s = %s bytes", \
			cmd, (*(file) == '/') ? "" : curdir(), file, \
			   off_to_str (cnt)); \
	}

static void ack (const char *);
static void authentication_setup (const char *);
#ifdef HAVE_LIBWRAP
static int  check_host (struct sockaddr *sa);
#endif
static void complete_login (struct credentials *);
static char *curdir (void);
static FILE *dataconn (const char *, off_t, const char *);
static void dolog (struct sockaddr_in *, struct credentials *);
static void end_login (struct credentials *);
static FILE *getdatasock (const char *);
static char *gunique (const char *);
static void lostconn (int);
static void myoob (int);
static int  receive_data (FILE *, FILE *);
static void send_data (FILE *, FILE *, off_t);
static void sigquit (int);
static void usage (int);

static const char *short_options = "Aa:Ddlp:qt:T:u:";
static struct option long_options[] =
{
  { "anonymous-only", no_argument, 0, 'A' },
  { "auth", required_argument, 0, 'a' },
  { "daemon", no_argument, 0, 'D' },
  { "debug", no_argument, 0, 'd' },
  { "help", no_argument, 0, '&' },
  { "logging", no_argument, 0, 'l' },
  { "pidfile", required_argument, 0, 'p' },
  { "no-version", no_argument, 0, 'q' },
  { "timeout", required_argument, 0, 't' },
  { "max-timeout", required_argument, 0, 'T' },
  { "umask", required_argument, 0, 'u' },
  { "version", no_argument, 0, 'V' },
  { 0, 0, 0, 0 }
};

static void
usage (int err)
{
  if (err != 0)
    {
      fprintf (stderr, "Usage: %s [OPTION] ...\n", program_name);
      fprintf (stderr, "Try `%s --help' for more information.\n", program_name);
    }
  else
    {
      fprintf (stdout, "Usage: %s [OPTION] ...\n", program_name);
      puts ("Internet File Transfer Protocol server.\n\n\
  -A, --anonymous-only      Server configure for anonymous service only\n\
  -D, --daemon              Start the ftpd standalone\n\
  -d, --debug               Debug mode\n\
  -l, --logging             Increase verbosity of syslog messages\n\
  -p, --pidfile=[PIDFILE]   Change default location of pidfile\n\
  -q, --no-version          Do not display version in banner\n\
  -t, --timeout=[TIMEOUT]   Set default idle timeout\n\
  -T, --max-timeout         Reset maximum value of timeout allowed\n\
  -u, --umask               Set default umask(base 8)\n\
      --help                Print this message\n\
  -V, --version             Print version\n\
  -a, --auth=[AUTH]         Use AUTH for authentication, it can be:\n\
                               default     passwd authentication.");
#ifdef WITH_PAM
      puts ("\
                               pam         using pam 'ftp' module.");
#endif
#ifdef WITH_KERBEROS
      puts ("\
                               kerberos");
#endif
#ifdef WITH_KERBEROS5
      puts ("\
                               kderberos5");
#endif
#ifdef WITH_OPIE
      puts ("\
                               opie");
#endif

      fprintf (stdout, "\nSubmit bug reports to %s.\n", PACKAGE_BUGREPORT);
    }
  exit (err);
}

int
main(int argc, char *argv[], char **envp)
{
  int option;

  program_name = argv[0];

#ifdef HAVE_TZSET
  tzset(); /* In case no timezone database in ~ftp.  */
#endif

#ifdef HAVE_INITSETPROCTITLE
  /* Save start and extent of argv for setproctitle.  */
  initsetproctitle (argc, argv, envp);
#endif /* HAVE_INITSETPROCTITLE */

  while ((option = getopt_long (argc, argv, short_options,
				long_options, NULL)) != EOF)
    {
      switch (option)
	{
	case 'A': /* Anonymous ftp only.  */
	  anon_only = 1;
	  break;

	case 'a': /* Authentification method.  */
	  if (strcasecmp (optarg, "default") == 0)
	    cred.auth_type = AUTH_TYPE_PASSWD;
#ifdef WITH_PAM
	  else if (strcasecmp (optarg, "pam") == 0)
	    cred.auth_type = AUTH_TYPE_PAM;
#endif
#ifdef WITH_KERBEROS
	  else if (stracasecmp (optarg, "kerberos") == 0)
	    cred.auth_type = AUTH_TYPE_KERBEROS;
#endif
#ifdef WITH_KERBEROS5
	  else if (stracasecmp (optarg, "kerberos5") == 0)
	    cred.auth_type = AUTH_TYPE_KERBEROS5;
#endif
#ifdef WITH_OPIE
	  else if (stracasecmp (optarg, "opie") == 0)
	    cred.auth_type = AUTH_TYPE_OPIE;
#endif
	  break;

	case 'D': /* Run ftpd as daemon.  */
	  daemon_mode = 1;
	  break;

	case 'd': /* Enable debug mode.  */
	  debug = 1;
	  break;

	case 'l': /* Increase logging level.  */
	  logging++;	/* > 1 == Extra logging.  */
	  break;

	case 'p': /* Override pid file */
	  pid_file = optarg;
	  break;

	case 'q': /* Don't include version number in banner.  */
	  no_version = 1;
	  break;

	case 't': /* Set default timeout value.  */
	  timeout = atoi (optarg);
	  if (maxtimeout < timeout)
	    maxtimeout = timeout;
	  break;

	case 'T': /* Maximum timeout allowed.  */
	  maxtimeout = atoi (optarg);
	  if (timeout > maxtimeout)
	    timeout = maxtimeout;
	  break;

	case 'u': /* Set umask.  */
	  {
	    long val = 0;

	    val = strtol (optarg, &optarg, 8);
	    if (*optarg != '\0' || val < 0)
	      fprintf (stderr, "%s: bad value for -u", argv[0]);
	    else
	      defumask = val;
	    break;
	  }

	case '&': /* Usage.  */
	  usage (0);
	  /* Not reached.  */

	case 'V': /* Version.  */
	  printf ("ftpd (%s) %s\n", PACKAGE_NAME, PACKAGE_VERSION);
	  exit (0);

	case '?':
	default:
	  usage (1);
	  /* Not reached.  */
	}
    }

  /* Bail out, wrong usage */
  argc -= optind;
  if (argc != 0)
    usage (1);

  /* LOG_NDELAY sets up the logging connection immediately,
     necessary for anonymous ftp's that chroot and can't do it later.  */
  openlog ("ftpd", LOG_PID | LOG_NDELAY, LOG_FTP);
  freopen (PATH_DEVNULL, "w", stderr);

  /* If not running via inetd, we detach and dup(fd, 0), dup(fd, 1) the
     fd = accept(). tcpd is check if compile with the support  */
  if (daemon_mode)
    {
      if (server_mode (pid_file, &his_addr) < 0)
	exit (1);
    }
  else
    {
      int addrlen = sizeof (his_addr);
      if (getpeername (STDIN_FILENO, (struct sockaddr *)&his_addr,
		       &addrlen) < 0)
	{
	  syslog (LOG_ERR, "getpeername (%s): %m", program_name);
	  exit (1);
	}
    }

  signal (SIGHUP, sigquit);
  signal (SIGINT, sigquit);
  signal (SIGQUIT, sigquit);
  signal (SIGTERM, sigquit);
  signal (SIGPIPE, lostconn);
  signal (SIGCHLD, SIG_IGN);
  if (signal (SIGURG, myoob) == SIG_ERR)
    syslog (LOG_ERR, "signal: %m");

  /* Get info on the ctrl connection.  */
  {
    int addrlen = sizeof (ctrl_addr);
    if (getsockname (STDIN_FILENO, (struct sockaddr *)&ctrl_addr,
		     &addrlen) < 0)
      {
	syslog (LOG_ERR, "getsockname (%s): %m", program_name);
	exit (1);
      }
  }

#if defined (IP_TOS) && defined (IPTOS_LOWDELAY) && defined (IPPROTO_IP)
  /* To  minimize delays for interactive traffic.  */
  {
    int tos = IPTOS_LOWDELAY;
    if (setsockopt (STDIN_FILENO, IPPROTO_IP, IP_TOS,
		    (char *)&tos, sizeof(int)) < 0)
      syslog (LOG_WARNING, "setsockopt (IP_TOS): %m");
  }
#endif

#ifdef SO_OOBINLINE
  /* Try to handle urgent data inline.  */
  {
    int on = 1;
    if (setsockopt (STDIN_FILENO, SOL_SOCKET, SO_OOBINLINE,
		    (char *)&on, sizeof (on)) < 0)
      syslog (LOG_ERR, "setsockopt: %m");