crypt-gpgme.c

mutt-1.5.12 源代码。linux 下邮件接受的工具。

/* crypt-gpgme.c - GPGME based crypto operations
 * Copyright (C) 1996,1997 Michael R. Elkins <[e-mail]>
 * Copyright (C) 1998,1999,2000 Thomas Roessler <[e-mail]>
 * Copyright (C) 2001  Thomas Roessler <[e-mail]>
 *                     Oliver Ehli <[e-mail]>
 * Copyright (C) 2002, 2003, 2004 g10 Code GmbH
 *
 *     This program 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 2 of the License, or
 *     (at your option) any later version.
 * 
 *     This program 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, write to the Free Software
 *     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef CRYPT_BACKEND_GPGME

#include "mutt.h"
#include "mutt_crypt.h"
#include "mutt_menu.h"
#include "mutt_curses.h"
#include "mime.h"
#include "copy.h"
#include "pager.h"
#include "sort.h"

#include <sys/wait.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <errno.h>
#include <ctype.h>

#include <gpgme.h>

#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif
#ifdef HAVE_LANGINFO_D_T_FMT
#include <langinfo.h>
#endif

#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif

#ifdef HAVE_SYS_RESOURCE_H
# include <sys/resource.h>
#endif

/*
 * Helper macros.
 */
#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))

/* Values used for comparing addresses. */
#define CRYPT_KV_VALID    1
#define CRYPT_KV_ADDR     2
#define CRYPT_KV_STRING   4
#define CRYPT_KV_STRONGID 8
#define CRYPT_KV_MATCH (CRYPT_KV_ADDR|CRYPT_KV_STRING)

/*
 * Type definitions.
 */

struct crypt_cache
{
  char *what;
  char *dflt;
  struct crypt_cache *next;
};

struct dn_array_s
{
  char *key;
  char *value;
};

/* We work based on user IDs, getting from a user ID to the key is
   check and does not need any memory (gpgme uses reference counting). */
typedef struct crypt_keyinfo
{
  struct crypt_keyinfo *next;
  gpgme_key_t kobj;
  int idx;             /* and the user ID at this index */
  const char *uid;     /* and for convenience point to this user ID */
  unsigned int flags;  /* global and per uid flags (for convenience)*/
} crypt_key_t;

typedef struct crypt_entry
{
  size_t num;
  crypt_key_t *key;
} crypt_entry_t;


static struct crypt_cache *id_defaults = NULL;
static gpgme_key_t signature_key = NULL;

/*
 * General helper functions.
 */

/* return true when S pints to a didgit or letter. */
static int
digit_or_letter (const unsigned char *s)
{
  return ( (*s >= '0' && *s < '9')
           || (*s >= 'A' && *s <= 'Z')
           || (*s >= 'a' && *s <= 'z'));
}


/* Print the utf-8 encoded string BUF of length LEN bytes to stream
   FP. Convert the character set. */
static void
print_utf8 (FILE *fp, const char *buf, size_t len)
{
  char *tstr;

  tstr = safe_malloc (len+1);
  memcpy (tstr, buf, len);
  tstr[len] = 0;
  mutt_convert_string (&tstr, "utf-8", Charset, M_ICONV_HOOK_FROM);
  fputs (tstr, fp);
  FREE (&tstr);
}


/*
 * Key management.
 */

/* Return the keyID for the key K.  Note that this string is valid as
   long as K is valid */
static const char *crypt_keyid (crypt_key_t *k)
{
  const char *s = "????????";

  if (k->kobj && k->kobj->subkeys)
    {
      s = k->kobj->subkeys->keyid;
      if ((! option (OPTPGPLONGIDS)) && (strlen (s) == 16))
	/* Return only the short keyID.  */
	s += 8;
    }

  return s;
}

/* Return the hexstring fingerprint from the key K. */
static const char *crypt_fpr (crypt_key_t *k)
{
  const char *s = "";

  if (k->kobj && k->kobj->subkeys)
    s = k->kobj->subkeys->fpr;

  return s;
}

/* Parse FLAGS and return a statically allocated(!) string with them. */
static char *crypt_key_abilities (int flags)
{
  static char buff[3];

  if (!(flags & KEYFLAG_CANENCRYPT))
    buff[0] = '-';
  else if (flags & KEYFLAG_PREFER_SIGNING)
    buff[0] = '.';
  else
    buff[0] = 'e';

  if (!(flags & KEYFLAG_CANSIGN))
    buff[1] = '-';
  else if (flags & KEYFLAG_PREFER_ENCRYPTION)
    buff[1] = '.';
  else
    buff[1] = 's';

  buff[2] = '\0';

  return buff;
}

/* Parse FLAGS and return a character describing the most important flag. */
static char crypt_flags (int flags)
{
  if (flags & KEYFLAG_REVOKED)
    return 'R';
  else if (flags & KEYFLAG_EXPIRED)
    return 'X';
  else if (flags & KEYFLAG_DISABLED)
    return 'd';
  else if (flags & KEYFLAG_CRITICAL)
    return 'c';
  else 
    return ' ';
}

/* Return a copy of KEY. */
static crypt_key_t *crypt_copy_key (crypt_key_t *key)
{
  crypt_key_t *k;

  k = safe_calloc (1, sizeof *k);
  k->kobj = key->kobj;
  gpgme_key_ref (key->kobj);
  k->idx = key->idx;
  k->uid = key->uid;
  k->flags = key->flags;

  return k;
}

/* Release all the keys at the address of KEYLIST and set the address
   to NULL. */
static void crypt_free_key (crypt_key_t **keylist)
{
  while (*keylist)
    {
      crypt_key_t *k = (*keylist)->next;
      FREE (&k);
      *keylist = k;
    }
}

/* Return trute when key K is valid. */
static int crypt_key_is_valid (crypt_key_t *k)
{
  if (k->flags & KEYFLAG_CANTUSE)
    return 0;
  return 1;
}

/* Return true whe validity of KEY is sufficient. */
static int crypt_id_is_strong (crypt_key_t *key)
{
  gpgme_validity_t val = GPGME_VALIDITY_UNKNOWN;
  gpgme_user_id_t uid = NULL;
  unsigned int is_strong = 0;
  unsigned int i = 0;

  if ((key->flags & KEYFLAG_ISX509))
    return 1;

  for (i = 0, uid = key->kobj->uids; (i < key->idx) && uid;
       i++, uid = uid->next)
    ;
  if (uid)
    val = uid->validity;

  switch (val)
    {
    case GPGME_VALIDITY_UNKNOWN:
    case GPGME_VALIDITY_UNDEFINED:
    case GPGME_VALIDITY_NEVER:
    case GPGME_VALIDITY_MARGINAL:
      is_strong = 0;
      break;

    case GPGME_VALIDITY_FULL:
    case GPGME_VALIDITY_ULTIMATE:
      is_strong = 1;
      break;
    }

  return is_strong;
}

/* Return true when the KEY is valid, i.e. not marked as unusable. */
static int crypt_id_is_valid (crypt_key_t *key)
{
  return ! (key->flags & KEYFLAG_CANTUSE);
}

/* Return a bit vector describing how well the addresses ADDR and
   U_ADDR match and whether KEY is valid. */
static int crypt_id_matches_addr (ADDRESS *addr, ADDRESS *u_addr,
                                  crypt_key_t *key)
{
  int rv = 0;
  
  if (crypt_id_is_valid (key))
    rv |= CRYPT_KV_VALID;

  if (crypt_id_is_strong (key))
    rv |= CRYPT_KV_STRONGID;
  
  if (addr->mailbox && u_addr->mailbox
      && mutt_strcasecmp (addr->mailbox, u_addr->mailbox) == 0)
    rv |= CRYPT_KV_ADDR;
    
  if (addr->personal && u_addr->personal
      && mutt_strcasecmp (addr->personal, u_addr->personal) == 0)
    rv |= CRYPT_KV_STRING;
  
  return rv;
}


/*
 * GPGME convenient functions.
 */

/* Create a new gpgme context and return it.  With FOR_SMIME set to
   true, the protocol of the context is set to CMS. */
static gpgme_ctx_t create_gpgme_context (int for_smime)
{
  gpgme_error_t err;
  gpgme_ctx_t ctx;

  err = gpgme_new (&ctx);
  if (err)
    {
      mutt_error (_("error creating gpgme context: %s\n"), gpgme_strerror (err));
      sleep (2);
      mutt_exit (1);
    }

  if (for_smime)
    {
      err = gpgme_set_protocol (ctx, GPGME_PROTOCOL_CMS);
      if (err)
        {
          mutt_error (_("error enabling CMS protocol: %s\n"),
                      gpgme_strerror (err));
          sleep (2);
          mutt_exit (1);
        }
    }

  return ctx;
}

/* Create a new gpgme data object.  This is a wrapper to die on
   error. */
static gpgme_data_t create_gpgme_data (void)
{
  gpgme_error_t err;
  gpgme_data_t data;

  err = gpgme_data_new (&data);
  if (err) 
    {
      mutt_error (_("error creating gpgme data object: %s\n"),
                  gpgme_strerror (err));
      sleep (2);
      mutt_exit (1);
    }
  return data;
}

/* Create a new GPGME Data object from the mail body A.  With CONVERT
   passed as true, the lines are converted to CR,LF if required.
   Return NULL on error or the gpgme_data_t object on success. */
static gpgme_data_t body_to_data_object (BODY *a, int convert)
{
  char tempfile[_POSIX_PATH_MAX];
  FILE *fptmp;
  int err = 0;
  gpgme_data_t data;
  
  mutt_mktemp (tempfile);
  fptmp = safe_fopen (tempfile, "w+");
  if (!fptmp)
    {
      mutt_perror (tempfile);
      return NULL;
    }

  mutt_write_mime_header (a, fptmp);
  fputc ('\n', fptmp);
  mutt_write_mime_body (a, fptmp);

  if (convert)
    {
      int c, hadcr = 0;
      unsigned char buf[1];

      data = create_gpgme_data ();
      rewind (fptmp);
      while ((c = fgetc (fptmp)) != EOF)
        {
          if  (c == '\r')
            hadcr = 1;
          else 
            {
              if (c == '\n' && !hadcr)
                {
                  buf[0] = '\r';
                  gpgme_data_write (data, buf, 1);
                }
                  
              hadcr = 0;
            }
          /* FIXME: This is quite suboptimal */
          buf[0] = c;
          gpgme_data_write (data, buf, 1);
        }
      fclose(fptmp);
      gpgme_data_seek (data, 0, SEEK_SET);
    }
  else
    {
      fclose(fptmp);
      err = gpgme_data_new_from_file (&data, tempfile, 1);
    }
  unlink (tempfile);
  if (err) 
    {
      mutt_error (_("error allocating data object: %s\n"), gpgme_strerror (err));
      return NULL;
    }

  return data;
}

/* Create a GPGME data object from the stream FP but limit the object
   to LENGTH bytes starting at OFFSET bytes from the beginning of the
   file. */
static gpgme_data_t file_to_data_object (FILE *fp, long offset, long length)
{
  int err = 0;
  gpgme_data_t data;
  
  err = gpgme_data_new_from_filepart (&data, NULL, fp, offset, length);
  if (err) 
    {
      mutt_error (_("error allocating data object: %s\n"), gpgme_strerror (err));
      return NULL;
    }

  return data;
}

/* Write a GPGME data object to the stream FP. */
static int data_object_to_stream (gpgme_data_t data, FILE *fp)
{
  int err;
  char buf[4096], *p;
  ssize_t nread;

  err = ((gpgme_data_seek (data, 0, SEEK_SET) == -1)
         ? gpgme_error_from_errno (errno) : 0);
  if (err)
    {
      mutt_error (_("error rewinding data object: %s\n"), gpgme_strerror (err));
      return -1;
    }

  while ((nread = gpgme_data_read (data, buf, sizeof (buf))))
    {
      /* fixme: we are not really converting CRLF to LF but just
         skipping CR. Doing it correctly needs a more complex logic */
      for (p=buf; nread; p++, nread--)
        {
          if (*p != '\r')
            putc (*p, fp);
        }

     if (ferror (fp))
       {
         mutt_perror ("[tempfile]");
         return -1;
       }
    }
  if (nread == -1)
    {
      mutt_error (_("error reading data object: %s\n"), strerror (errno));
      return -1;
    }
  return 0;
}

/* Copy a data object to a newly created temporay file and return that
   filename. Caller must free.  With RET_FP not NULL, don't close the
   stream but return it there. */
static char *data_object_to_tempfile (gpgme_data_t data, FILE **ret_fp)
{
  int err;
  char tempfile[_POSIX_PATH_MAX];
  FILE *fp;
  size_t nread = 0;