ftp-basic.c

Wget很好的处理了http和ftp的下载,很值得学习的经典代码

/* Basic FTP routines.
   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
   2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.

This file is part of GNU Wget.

GNU Wget is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
 (at your option) any later version.

GNU Wget is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Wget.  If not, see <http://www.gnu.org/licenses/>.

Additional permission under GNU GPL version 3 section 7

If you modify this program, or any covered work, by linking or
combining it with the OpenSSL project's OpenSSL library (or a
modified version of that library), containing parts covered by the
terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
grants you additional permission to convey the resulting work.
Corresponding Source for a non-source form of such a combination
shall include the source code for the parts of OpenSSL used as well
as that of the covered work.  */

#include <config.h>

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

#include <string.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif

#include "wget.h"
#include "utils.h"
#include "connect.h"
#include "host.h"
#include "ftp.h"
#include "retr.h"

char ftp_last_respline[128];


/* Get the response of FTP server and allocate enough room to handle
   it.  <CR> and <LF> characters are stripped from the line, and the
   line is 0-terminated.  All the response lines but the last one are
   skipped.  The last line is determined as described in RFC959.

   If the line is successfully read, FTPOK is returned, and *ret_line
   is assigned a freshly allocated line.  Otherwise, FTPRERR is
   returned, and the value of *ret_line should be ignored.  */

uerr_t
ftp_response (int fd, char **ret_line)
{
  while (1)
    {
      char *p;
      char *line = fd_read_line (fd);
      if (!line)
        return FTPRERR;

      /* Strip trailing CRLF before printing the line, so that
         escnonprint doesn't include bogus \012 and \015. */
      p = strchr (line, '\0');
      if (p > line && p[-1] == '\n')
        *--p = '\0';
      if (p > line && p[-1] == '\r')
        *--p = '\0';

      if (opt.server_response)
        logprintf (LOG_NOTQUIET, "%s\n", escnonprint (line));
      else
        DEBUGP (("%s\n", escnonprint (line)));

      /* The last line of output is the one that begins with "ddd ". */
      if (ISDIGIT (line[0]) && ISDIGIT (line[1]) && ISDIGIT (line[2])
          && line[3] == ' ')
        {
          strncpy (ftp_last_respline, line, sizeof (ftp_last_respline));
          ftp_last_respline[sizeof (ftp_last_respline) - 1] = '\0';
          *ret_line = line;
          return FTPOK;
        }
      xfree (line);
    }
}

/* Returns the malloc-ed FTP request, ending with <CR><LF>, printing
   it if printing is required.  If VALUE is NULL, just use
   command<CR><LF>.  */
static char *
ftp_request (const char *command, const char *value)
{
  char *res;
  if (value)
    {
      /* Check for newlines in VALUE (possibly injected by the %0A URL
         escape) making the callers inadvertently send multiple FTP
         commands at once.  Without this check an attacker could
         intentionally redirect to ftp://server/fakedir%0Acommand.../
         and execute arbitrary FTP command on a remote FTP server.  */
      if (strpbrk (value, "\r\n"))
        {
          /* Copy VALUE to the stack and modify CR/LF to space. */
          char *defanged, *p;
          STRDUP_ALLOCA (defanged, value);
          for (p = defanged; *p; p++)
            if (*p == '\r' || *p == '\n')
              *p = ' ';
          DEBUGP (("\nDetected newlines in %s \"%s\"; changing to %s \"%s\"\n",
                   command, escnonprint (value), command, escnonprint (defanged)));
          /* Make VALUE point to the defanged copy of the string. */
          value = defanged;
        }
      res = concat_strings (command, " ", value, "\r\n", (char *) 0);
    }
  else
    res = concat_strings (command, "\r\n", (char *) 0);
  if (opt.server_response)
    {
      /* Hack: don't print out password.  */
      if (strncmp (res, "PASS", 4) != 0)
        logprintf (LOG_ALWAYS, "--> %s\n", res);
      else
        logputs (LOG_ALWAYS, "--> PASS Turtle Power!\n\n");
    }
  else
    DEBUGP (("\n--> %s\n", res));
  return res;
}

/* Sends the USER and PASS commands to the server, to control
   connection socket csock.  */
uerr_t
ftp_login (int csock, const char *acc, const char *pass)
{
  uerr_t err;
  char *request, *respline;
  int nwritten;

  /* Get greeting.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '2')
    {
      xfree (respline);
      return FTPSRVERR;
    }
  xfree (respline);
  /* Send USER username.  */
  request = ftp_request ("USER", acc);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  /* An unprobable possibility of logging without a password.  */
  if (*respline == '2')
    {
      xfree (respline);
      return FTPOK;
    }
  /* Else, only response 3 is appropriate.  */
  if (*respline != '3')
    {
      xfree (respline);
      return FTPLOGREFUSED;
    }
#ifdef ENABLE_OPIE
  {
    static const char *skey_head[] = {
      "331 s/key ",
      "331 opiekey "
    };
    int i;
    const char *seed = NULL;

    for (i = 0; i < countof (skey_head); i++)
      {
        int l = strlen (skey_head[i]);
        if (0 == strncasecmp (skey_head[i], respline, l))
          {
            seed = respline + l;
            break;
          }
      }
    if (seed)
      {
        int skey_sequence = 0;

        /* Extract the sequence from SEED.  */
        for (; ISDIGIT (*seed); seed++)
          skey_sequence = 10 * skey_sequence + *seed - '0';
        if (*seed == ' ')
          ++seed;
        else
          {
            xfree (respline);
            return FTPLOGREFUSED;
          }
        /* Replace the password with the SKEY response to the
           challenge.  */
        pass = skey_response (skey_sequence, seed, pass);
      }
  }
#endif /* ENABLE_OPIE */
  xfree (respline);
  /* Send PASS password.  */
  request = ftp_request ("PASS", pass);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '2')
    {
      xfree (respline);
      return FTPLOGINC;
    }
  xfree (respline);
  /* All OK.  */
  return FTPOK;
}

static void
ip_address_to_port_repr (const ip_address *addr, int port, char *buf, 
                         size_t buflen)
{
  unsigned char *ptr;

  assert (addr->family == AF_INET);
  /* buf must contain the argument of PORT (of the form a,b,c,d,e,f). */
  assert (buflen >= 6 * 4);

  ptr = IP_INADDR_DATA (addr);
  snprintf (buf, buflen, "%d,%d,%d,%d,%d,%d", ptr[0], ptr[1],
            ptr[2], ptr[3], (port & 0xff00) >> 8, port & 0xff);
  buf[buflen - 1] = '\0';
}

/* Bind a port and send the appropriate PORT command to the FTP
   server.  Use acceptport after RETR, to get the socket of data
   connection.  */
uerr_t
ftp_port (int csock, int *local_sock)
{
  uerr_t err;
  char *request, *respline;
  ip_address addr;
  int nwritten;
  int port;
  /* Must contain the argument of PORT (of the form a,b,c,d,e,f). */
  char bytes[6 * 4 + 1];

  /* Get the address of this side of the connection. */
  if (!socket_ip_address (csock, &addr, ENDPOINT_LOCAL))
    return FTPSYSERR;

  assert (addr.family == AF_INET);

  /* Setting port to 0 lets the system choose a free port.  */
  port = 0;

  /* Bind the port.  */
  *local_sock = bind_local (&addr, &port);
  if (*local_sock < 0)
    return FTPSYSERR;

  /* Construct the argument of PORT (of the form a,b,c,d,e,f). */
  ip_address_to_port_repr (&addr, port, bytes, sizeof (bytes));

  /* Send PORT request.  */
  request = ftp_request ("PORT", bytes);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      fd_close (*local_sock);
      return WRITEFAILED;
    }
  xfree (request);

  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    {
      fd_close (*local_sock);
      return err;
    }
  if (*respline != '2')
    {
      xfree (respline);
      fd_close (*local_sock);
      return FTPPORTERR;
    }
  xfree (respline);
  return FTPOK;
}

#ifdef ENABLE_IPV6
static void
ip_address_to_lprt_repr (const ip_address *addr, int port, char *buf, 
                         size_t buflen)
{
  unsigned char *ptr = IP_INADDR_DATA (addr);

  /* buf must contain the argument of LPRT (of the form af,n,h1,h2,...,hn,p1,p2). */
  assert (buflen >= 21 * 4);

  /* Construct the argument of LPRT (of the form af,n,h1,h2,...,hn,p1,p2). */
  switch (addr->family) 
    {
    case AF_INET: 
      snprintf (buf, buflen, "%d,%d,%d,%d,%d,%d,%d,%d,%d", 4, 4, 
                ptr[0], ptr[1], ptr[2], ptr[3], 2,
                (port & 0xff00) >> 8, port & 0xff);
      break;
    case AF_INET6: 
      snprintf (buf, buflen,
                "%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",
                6, 16,
                ptr[0], ptr[1], ptr[2], ptr[3], ptr[4], ptr[5], ptr[6], ptr[7], 
                ptr[8], ptr[9], ptr[10], ptr[11], ptr[12], ptr[13], ptr[14], ptr[15],
                2, (port & 0xff00) >> 8, port & 0xff);
      break;
    default:
      abort ();
    }
}

/* Bind a port and send the appropriate PORT command to the FTP
   server.  Use acceptport after RETR, to get the socket of data
   connection.  */
uerr_t
ftp_lprt (int csock, int *local_sock)
{
  uerr_t err;
  char *request, *respline;
  ip_address addr;
  int nwritten;
  int port;
  /* Must contain the argument of LPRT (of the form af,n,h1,h2,...,hn,p1,p2). */
  char bytes[21 * 4 + 1];

  /* Get the address of this side of the connection. */
  if (!socket_ip_address (csock, &addr, ENDPOINT_LOCAL))
    return FTPSYSERR;

  assert (addr.family == AF_INET || addr.family == AF_INET6);

  /* Setting port to 0 lets the system choose a free port.  */
  port = 0;

  /* Bind the port.  */
  *local_sock = bind_local (&addr, &port);
  if (*local_sock < 0)
    return FTPSYSERR;

  /* Construct the argument of LPRT (of the form af,n,h1,h2,...,hn,p1,p2). */
  ip_address_to_lprt_repr (&addr, port, bytes, sizeof (bytes));

  /* Send PORT request.  */
  request = ftp_request ("LPRT", bytes);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      fd_close (*local_sock);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    {
      fd_close (*local_sock);
      return err;
    }
  if (*respline != '2')
    {
      xfree (respline);
      fd_close (*local_sock);
      return FTPPORTERR;
    }
  xfree (respline);
  return FTPOK;
}

static void
ip_address_to_eprt_repr (const ip_address *addr, int port, char *buf, 
                         size_t buflen)
{
  int afnum;

  /* buf must contain the argument of EPRT (of the form |af|addr|port|). 
   * 4 chars for the | separators, INET6_ADDRSTRLEN chars for addr  
   * 1 char for af (1-2) and 5 chars for port (0-65535) */
  assert (buflen >= 4 + INET6_ADDRSTRLEN + 1 + 5); 

  /* Construct the argument of EPRT (of the form |af|addr|port|). */
  afnum = (addr->family == AF_INET ? 1 : 2);
  snprintf (buf, buflen, "|%d|%s|%d|", afnum, print_address (addr), port);
  buf[buflen - 1] = '\0';
}

/* Bind a port and send the appropriate PORT command to the FTP
   server.  Use acceptport after RETR, to get the socket of data
   connection.  */
uerr_t
ftp_eprt (int csock, int *local_sock)
{
  uerr_t err;
  char *request, *respline;
  ip_address addr;
  int nwritten;
  int port;
  /* Must contain the argument of EPRT (of the form |af|addr|port|). 
   * 4 chars for the | separators, INET6_ADDRSTRLEN chars for addr  
   * 1 char for af (1-2) and 5 chars for port (0-65535) */
  char bytes[4 + INET6_ADDRSTRLEN + 1 + 5 + 1];

  /* Get the address of this side of the connection. */
  if (!socket_ip_address (csock, &addr, ENDPOINT_LOCAL))
    return FTPSYSERR;

  /* Setting port to 0 lets the system choose a free port.  */
  port = 0;

  /* Bind the port.  */
  *local_sock = bind_local (&addr, &port);
  if (*local_sock < 0)
    return FTPSYSERR;

  /* Construct the argument of EPRT (of the form |af|addr|port|). */
  ip_address_to_eprt_repr (&addr, port, bytes, sizeof (bytes));

  /* Send PORT request.  */
  request = ftp_request ("EPRT", bytes);
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      fd_close (*local_sock);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get appropriate response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    {
      fd_close (*local_sock);
      return err;
    }
  if (*respline != '2')
    {
      xfree (respline);
      fd_close (*local_sock);
      return FTPPORTERR;
    }
  xfree (respline);
  return FTPOK;
}
#endif

/* Similar to ftp_port, but uses `PASV' to initiate the passive FTP
   transfer.  Reads the response from server and parses it.  Reads the
   host and port addresses and returns them.  */
uerr_t
ftp_pasv (int csock, ip_address *addr, int *port)
{
  char *request, *respline, *s;
  int nwritten, i;
  uerr_t err;
  unsigned char tmp[6];

  assert (addr != NULL);
  assert (port != NULL);

  xzero (*addr);

  /* Form the request.  */
  request = ftp_request ("PASV", NULL);
  /* And send it.  */
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);
  /* Get the server response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '2')
    {
      xfree (respline);
      return FTPNOPASV;
    }
  /* Parse the request.  */
  s = respline;
  for (s += 4; *s && !ISDIGIT (*s); s++)
    ;
  if (!*s)
    return FTPINVPASV;
  for (i = 0; i < 6; i++)
    {
      tmp[i] = 0;
      for (; ISDIGIT (*s); s++)
        tmp[i] = (*s - '0') + 10 * tmp[i];
      if (*s == ',')
        s++;
      else if (i < 5)
        {
          /* When on the last number, anything can be a terminator.  */
          xfree (respline);
          return FTPINVPASV;
        }
    }
  xfree (respline);

  addr->family = AF_INET;
  memcpy (IP_INADDR_DATA (addr), tmp, 4);
  *port = ((tmp[4] << 8) & 0xff00) + tmp[5];

  return FTPOK;
}

#ifdef ENABLE_IPV6
/* Similar to ftp_lprt, but uses `LPSV' to initiate the passive FTP
   transfer.  Reads the response from server and parses it.  Reads the
   host and port addresses and returns them.  */
uerr_t
ftp_lpsv (int csock, ip_address *addr, int *port)
{
  char *request, *respline, *s;
  int nwritten, i, af, addrlen, portlen;
  uerr_t err;
  unsigned char tmp[16];
  unsigned char tmpprt[2];

  assert (addr != NULL);
  assert (port != NULL);

  xzero (*addr);

  /* Form the request.  */
  request = ftp_request ("LPSV", NULL);

  /* And send it.  */
  nwritten = fd_write (csock, request, strlen (request), -1);
  if (nwritten < 0)
    {
      xfree (request);
      return WRITEFAILED;
    }
  xfree (request);

  /* Get the server response.  */
  err = ftp_response (csock, &respline);
  if (err != FTPOK)
    return err;
  if (*respline != '2')
    {
      xfree (respline);
      return FTPNOPASV;
    }