gnupg/common/simple-pwquery.c

/* simple-pwquery.c - A simple password query client for gpg-agent
 *	Copyright (C) 2002, 2004, 2007 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG 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.
 *
 * GnuPG 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 this program; if not, see <http://www.gnu.org/licenses/>.
 */

/* This module is intended as a standalone client implementation to
   gpg-agent's GET_PASSPHRASE command.  In particular it does not use
   the Assuan library and can only cope with an already running
   gpg-agent.  Some stuff is configurable in the header file. */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#ifdef HAVE_W32_SYSTEM
#include <winsock2.h>
#else
#include <sys/socket.h>
#include <sys/un.h>
#endif
#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif

#define GNUPG_COMMON_NEED_AFLOCAL
#include "../common/mischelp.h"
#ifdef HAVE_W32_SYSTEM
#include "../common/w32-afunix.h"
#endif


#define SIMPLE_PWQUERY_IMPLEMENTATION 1
#include "simple-pwquery.h"

#ifndef _
#define _(a) (a)
#endif

#if !defined (hexdigitp) && !defined (xtoi_2)
#define digitp(p)   (*(p) >= '0' && *(p) <= '9')
#define hexdigitp(a) (digitp (a)                     \
                      || (*(a) >= 'A' && *(a) <= 'F')  \
                      || (*(a) >= 'a' && *(a) <= 'f'))
#define xtoi_1(p)   (*(p) <= '9'? (*(p)- '0'): \
                     *(p) <= 'F'? (*(p)-'A'+10):(*(p)-'a'+10))
#define xtoi_2(p)   ((xtoi_1(p) * 16) + xtoi_1((p)+1))
#endif


/* Name of the socket to be used.  This is a kludge to keep on using
   the existsing code despite that we only support a standard socket.  */
static char *default_gpg_agent_info;





#ifndef HAVE_STPCPY
static char *
my_stpcpy(char *a,const char *b)
{
    while( *b )
	*a++ = *b++;
    *a = 0;

    return (char*)a;
}
#define stpcpy(a,b)  my_stpcpy((a), (b))
#endif



/* Write NBYTES of BUF to file descriptor FD. */
static int
writen (int fd, const void *buf, size_t nbytes)
{
  size_t nleft = nbytes;
  int nwritten;

  while (nleft > 0)
    {
#ifdef HAVE_W32_SYSTEM
      nwritten = send (fd, buf, nleft, 0);
#else
      nwritten = write (fd, buf, nleft);
#endif
      if (nwritten < 0)
        {
          if (errno == EINTR)
            nwritten = 0;
          else {
#ifdef SPWQ_USE_LOGGING
            log_error ("write failed: %s\n", strerror (errno));
#endif
            return SPWQ_IO_ERROR;
          }
        }
      nleft -= nwritten;
      buf = (const char*)buf + nwritten;
    }

  return 0;
}


/* Read an entire line and return number of bytes read. */
static int
readline (int fd, char *buf, size_t buflen)
{
  size_t nleft = buflen;
  char *p;
  int nread = 0;

  while (nleft > 0)
    {
#ifdef HAVE_W32_SYSTEM
      int n = recv (fd, buf, nleft, 0);
#else
      int n = read (fd, buf, nleft);
#endif
      if (n < 0)
        {
          if (errno == EINTR)
            continue;
          return -(SPWQ_IO_ERROR);
        }
      else if (!n)
        {
          return -(SPWQ_PROTOCOL_ERROR); /* incomplete line */
        }
      p = buf;
      nleft -= n;
      buf += n;
      nread += n;

      for (; n && *p != '\n'; n--, p++)
        ;
      if (n)
        {
          break; /* At least one full line available - that's enough.
                    This function is just a simple implementation, so
                    it is okay to forget about pending bytes.  */
        }
    }

  return nread;
}


/* Send an option to the agent */
static int
agent_send_option (int fd, const char *name, const char *value)
{
  char buf[200];
  int nread;
  char *line;
  int i;

  line = spwq_malloc (7 + strlen (name) + 1 + strlen (value) + 2);
  if (!line)
    return SPWQ_OUT_OF_CORE;
  strcpy (stpcpy (stpcpy (stpcpy (
                     stpcpy (line, "OPTION "), name), "="), value), "\n");
  i = writen (fd, line, strlen (line));
  spwq_free (line);
  if (i)
    return i;

  /* get response */
  nread = readline (fd, buf, DIM(buf)-1);
  if (nread < 0)
    return -nread;
  if (nread < 3)
    return SPWQ_PROTOCOL_ERROR;

  if (buf[0] == 'O' && buf[1] == 'K' && (buf[2] == ' ' || buf[2] == '\n'))
    return 0; /* okay */

  return SPWQ_ERR_RESPONSE;
}


/* Send all available options to the agent. */
static int
agent_send_all_options (int fd)
{
  char *dft_display = NULL;
  char *dft_ttyname = NULL;
  char *dft_ttytype = NULL;
  char *dft_xauthority = NULL;
  char *dft_pinentry_user_data = NULL;
  int rc = 0;

  dft_display = getenv ("DISPLAY");
  if (dft_display)
    {
      if ((rc = agent_send_option (fd, "display", dft_display)))
        return rc;
    }

  dft_ttyname = getenv ("GPG_TTY");
#if !defined(HAVE_W32_SYSTEM) && !defined(HAVE_BROKEN_TTYNAME)
  if ((!dft_ttyname || !*dft_ttyname) && ttyname (0))
    dft_ttyname = ttyname (0);
#endif
  if (dft_ttyname && *dft_ttyname)
    {
      if ((rc=agent_send_option (fd, "ttyname", dft_ttyname)))
        return rc;
    }

  dft_ttytype = getenv ("TERM");
  if (dft_ttyname && dft_ttytype)
    {
      if ((rc = agent_send_option (fd, "ttytype", dft_ttytype)))
        return rc;
    }

#if defined(HAVE_SETLOCALE)
  {
    char *old_lc = NULL;
    char *dft_lc = NULL;

#if defined(LC_CTYPE)
    old_lc = setlocale (LC_CTYPE, NULL);
    if (old_lc)
      {
        char *p = spwq_malloc (strlen (old_lc)+1);
        if (!p)
          return SPWQ_OUT_OF_CORE;
        strcpy (p, old_lc);
        old_lc = p;
      }
    dft_lc = setlocale (LC_CTYPE, "");
    if (dft_ttyname && dft_lc)
      rc = agent_send_option (fd, "lc-ctype", dft_lc);
    if (old_lc)
      {
        setlocale (LC_CTYPE, old_lc);
        spwq_free (old_lc);
      }
    if (rc)
      return rc;
#endif

#if defined(LC_MESSAGES)
    old_lc = setlocale (LC_MESSAGES, NULL);
    if (old_lc)
      {
        char *p = spwq_malloc (strlen (old_lc)+1);
        if (!p)
          return SPWQ_OUT_OF_CORE;
        strcpy (p, old_lc);
        old_lc = p;
      }
    dft_lc = setlocale (LC_MESSAGES, "");
    if (dft_ttyname && dft_lc)
      rc = agent_send_option (fd, "lc-messages", dft_lc);
    if (old_lc)
      {
        setlocale (LC_MESSAGES, old_lc);
        spwq_free (old_lc);
      }
    if (rc)
      return rc;
#endif
  }
#endif /*HAVE_SETLOCALE*/

  /* Send the XAUTHORITY variable.  */
  dft_xauthority = getenv ("XAUTHORITY");
  if (dft_xauthority)
    {
      /* We ignore errors here because older gpg-agents don't support
         this option.  */
      agent_send_option (fd, "xauthority", dft_xauthority);
    }

  /* Send the PINENTRY_USER_DATA variable.  */
  dft_pinentry_user_data = getenv ("PINENTRY_USER_DATA");
  if (dft_pinentry_user_data)
    {
      /* We ignore errors here because older gpg-agents don't support
         this option.  */
      agent_send_option (fd, "pinentry-user-data", dft_pinentry_user_data);
    }

  return 0;
}



/* Try to open a connection to the agent, send all options and return
   the file descriptor for the connection.  Return -1 in case of
   error. */
static int
agent_open (int *rfd)
{
  int rc;
  int fd;
  char *infostr, *p;
  struct sockaddr_un client_addr;
  size_t len;
  char line[200];
  int nread;

  *rfd = -1;
  infostr = default_gpg_agent_info;
  if ( !infostr || !*infostr )
    {
#ifdef SPWQ_USE_LOGGING
      log_error (_("no gpg-agent running in this session\n"));
#endif
      return SPWQ_NO_AGENT;
    }
  p = spwq_malloc (strlen (infostr)+1);
  if (!p)
    return SPWQ_OUT_OF_CORE;
  strcpy (p, infostr);
  infostr = p;

  if ( !(p = strchr ( infostr, PATHSEP_C)) || p == infostr
       || (p-infostr)+1 >= sizeof client_addr.sun_path )
    {
      return SPWQ_NO_AGENT;
    }
  *p++ = 0;

  while (*p && *p != PATHSEP_C)
    p++;

#ifdef HAVE_W32_SYSTEM
  fd = _w32_sock_new (AF_UNIX, SOCK_STREAM, 0);
#else
  fd = socket (AF_UNIX, SOCK_STREAM, 0);
#endif
  if (fd == -1)
    {
#ifdef SPWQ_USE_LOGGING
      log_error ("can't create socket: %s\n", strerror(errno) );
#endif
      return SPWQ_SYS_ERROR;
    }

  memset (&client_addr, 0, sizeof client_addr);
  client_addr.sun_family = AF_UNIX;
  strcpy (client_addr.sun_path, infostr);
  len = SUN_LEN (&client_addr);

#ifdef HAVE_W32_SYSTEM
  rc = _w32_sock_connect (fd, (struct sockaddr*)&client_addr, len );
#else
  rc = connect (fd, (struct sockaddr*)&client_addr, len );
#endif
  if (rc == -1)
    {
#ifdef SPWQ_USE_LOGGING
      log_error ( _("can't connect to '%s': %s\n"), infostr, strerror (errno));
#endif
      close (fd );
      return SPWQ_IO_ERROR;
    }

  nread = readline (fd, line, DIM(line));
  if (nread < 3 || !(line[0] == 'O' && line[1] == 'K'
                     && (line[2] == '\n' || line[2] == ' ')) )
    {
#ifdef SPWQ_USE_LOGGING
      log_error ( _("communication problem with gpg-agent\n"));
#endif
      close (fd );
      return SPWQ_PROTOCOL_ERROR;
    }

  rc = agent_send_all_options (fd);
  if (rc)
    {
#ifdef SPWQ_USE_LOGGING
      log_error (_("problem setting the gpg-agent options\n"));
#endif
      close (fd);
      return rc;
    }

  *rfd = fd;
  return 0;
}


/* Copy text to BUFFER and escape as required.  Return a pointer to
   the end of the new buffer.  Note that BUFFER must be large enough
   to keep the entire text; allocataing it 3 times the size of TEXT
   is sufficient. */
static char *
copy_and_escape (char *buffer, const char *text)
{
  int i;
  const unsigned char *s = (unsigned char *)text;
  char *p = buffer;


  for (i=0; s[i]; i++)
    {
      if (s[i] < ' ' || s[i] == '+')
        {
          sprintf (p, "%%%02X", s[i]);
          p += 3;
        }
      else if (s[i] == ' ')
        *p++ = '+';
      else
        *p++ = s[i];
    }
  return p;
}


/* Set the name of the default socket to NAME.  */
int
simple_pw_set_socket (const char *name)
{
  spwq_free (default_gpg_agent_info);
  if (name)
    {
      default_gpg_agent_info = spwq_malloc (strlen (name) + 4 + 1);
      if (!default_gpg_agent_info)
        return SPWQ_OUT_OF_CORE;
      /* We don't know the PID thus we use 0.  */
      strcpy (stpcpy (default_gpg_agent_info, name),
              PATHSEP_S "0" PATHSEP_S "1");
    }
  else
    default_gpg_agent_info = NULL;

  return 0;
}


/* Ask the gpg-agent for a passphrase and present the user with a
   DESCRIPTION, a PROMPT and optionally with a TRYAGAIN extra text.
   If a CACHEID is not NULL it is used to locate the passphrase in in
   the cache and store it under this ID.  If OPT_CHECK is true
   gpg-agent is asked to apply some checks on the passphrase security.
   If ERRORCODE is not NULL it should point a variable receiving an
   errorcode; this error code might be 0 if the user canceled the
   operation.  The function returns NULL to indicate an error.  */
char *
simple_pwquery (const char *cacheid,
                const char *tryagain,
                const char *prompt,
                const char *description,
                int opt_check,
                int *errorcode)
{
  int fd = -1;
  int nread;
  char *result = NULL;
  char *pw = NULL;
  char *p;
  int rc, i;

  rc = agent_open (&fd);
  if (rc)
    goto leave;

  if (!cacheid)
    cacheid = "X";
  if (!tryagain)
    tryagain = "X";
  if (!prompt)
    prompt = "X";
  if (!description)
    description = "X";

  {
    char *line;
    /* We allocate 3 times the needed space so that there is enough
       space for escaping. */
    line = spwq_malloc (15 + 10
                        + 3*strlen (cacheid) + 1
                        + 3*strlen (tryagain) + 1
                        + 3*strlen (prompt) + 1
                        + 3*strlen (description) + 1
                        + 2);
    if (!line)
      {
        rc = SPWQ_OUT_OF_CORE;
        goto leave;
      }
    strcpy (line, "GET_PASSPHRASE ");
    p = line+15;
    if (opt_check)
      p = stpcpy (p, "--check ");
    p = copy_and_escape (p, cacheid);
    *p++ = ' ';
    p = copy_and_escape (p, tryagain);
    *p++ = ' ';
    p = copy_and_escape (p, prompt);
    *p++ = ' ';
    p = copy_and_escape (p, description);
    *p++ = '\n';
    rc = writen (fd, line, p - line);
    spwq_free (line);
    if (rc)
      goto leave;
  }

  /* get response */
  pw = spwq_secure_malloc (500);
  nread = readline (fd, pw, 499);
  if (nread < 0)
    {
      rc = -nread;
      goto leave;
    }
  if (nread < 3)
    {
      rc = SPWQ_PROTOCOL_ERROR;
      goto leave;
    }

  if (pw[0] == 'O' && pw[1] == 'K' && pw[2] == ' ')
    { /* we got a passphrase - convert it back from hex */
      size_t pwlen = 0;

      for (i=3; i < nread && hexdigitp (pw+i); i+=2)
        pw[pwlen++] = xtoi_2 (pw+i);
      pw[pwlen] = 0; /* make a C String */
      result = pw;
      pw = NULL;
    }
  else if ((nread > 7 && !memcmp (pw, "ERR 111", 7)
            && (pw[7] == ' ' || pw[7] == '\n') )
           || ((nread > 4 && !memcmp (pw, "ERR ", 4)
                && (strtoul (pw+4, NULL, 0) & 0xffff) == 99)) )
    {
      /* 111 is the old Assuan code for canceled which might still
         be in use by old installations. 99 is GPG_ERR_CANCELED as
         used by modern gpg-agents; 0xffff is used to mask out the
         error source.  */
#ifdef SPWQ_USE_LOGGING
      log_info (_("canceled by user\n") );
#endif
      *errorcode = 0; /* Special error code to indicate Cancel. */
    }
  else if (nread > 4 && !memcmp (pw, "ERR ", 4))
    {
      switch ( (strtoul (pw+4, NULL, 0) & 0xffff) )
        {
        case 85: rc = SPWQ_NO_PIN_ENTRY;  break;
        default: rc = SPWQ_GENERAL_ERROR; break;
        }
    }
  else
    {
#ifdef SPWQ_USE_LOGGING
      log_error (_("problem with the agent\n"));
#endif
      rc = SPWQ_ERR_RESPONSE;
    }

 leave:
  if (errorcode)
    *errorcode = rc;
  if (fd != -1)
    close (fd);
  if (pw)
    spwq_secure_free (pw);
  return result;
}


/* Ask the gpg-agent to clear the passphrase for the cache ID CACHEID.  */
int
simple_pwclear (const char *cacheid)
{
  char line[500];
  char *p;

  /* We need not more than 50 characters for the command and the
     terminating nul.  */
  if (strlen (cacheid) * 3 > sizeof (line) - 50)
    return SPWQ_PROTOCOL_ERROR;

  strcpy (line, "CLEAR_PASSPHRASE ");
  p = line + 17;
  p = copy_and_escape (p, cacheid);
  *p++ = '\n';
  *p++ = '\0';

  return simple_query (line);
}


/* Perform the simple query QUERY (which must be new-line and 0
   terminated) and return the error code.  */
int
simple_query (const char *query)
{
  int fd = -1;
  int nread;
  char response[500];
  int have = 0;
  int rc;

  rc = agent_open (&fd);
  if (rc)
    goto leave;

  rc = writen (fd, query, strlen (query));
  if (rc)
    goto leave;

  while (1)
    {
      if (! have || ! strchr (response, '\n'))
        /* get response */
        {
          nread = readline (fd, &response[have],
                            sizeof (response) - 1 /* NUL */ - have);
          if (nread < 0)
            {
              rc = -nread;
              goto leave;
            }
          have += nread;
          if (have < 3)
            {
              rc = SPWQ_PROTOCOL_ERROR;
              goto leave;
            }
          response[have] = 0;
        }

      if (response[0] == 'O' && response[1] == 'K')
        /* OK, do nothing.  */;
      else if ((nread > 7 && !memcmp (response, "ERR 111", 7)
                && (response[7] == ' ' || response[7] == '\n') )
               || ((nread > 4 && !memcmp (response, "ERR ", 4)
                    && (strtoul (response+4, NULL, 0) & 0xffff) == 99)) )
        {
          /* 111 is the old Assuan code for canceled which might still
             be in use by old installations. 99 is GPG_ERR_CANCELED as
             used by modern gpg-agents; 0xffff is used to mask out the
             error source.  */
#ifdef SPWQ_USE_LOGGING
          log_info (_("canceled by user\n") );
#endif
        }
      else if (response[0] == 'S' && response[1] == ' ')
        {
          char *nextline;
          int consumed;

          nextline = strchr (response, '\n');
          if (! nextline)
            /* Point to the NUL.  */
            nextline = &response[have];
          else
            /* Move past the \n.  */
            nextline ++;

          consumed = (size_t) nextline - (size_t) response;

          /* Skip any additional newlines.  */
          while (consumed < have && response[consumed] == '\n')
            consumed ++;

          have -= consumed;

          if (have)
            memmove (response, &response[consumed], have + 1);

          continue;
        }
      else
        {
#ifdef SPWQ_USE_LOGGING
          log_error (_("problem with the agent (unexpected response \"%s\"\n"),
                     response);
#endif
          rc = SPWQ_ERR_RESPONSE;
        }

      break;
    }

 leave:
  if (fd != -1)
    close (fd);
  return rc;
}