Imported Upstream version 2.1.8

[platform/upstream/gpg2.git] / g10 / getkey.c

/* getkey.c -  Get a key from the database
 * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
 *               2007, 2008, 2010  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/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>

#include "gpg.h"
#include "util.h"
#include "packet.h"
#include "iobuf.h"
#include "keydb.h"
#include "options.h"
#include "main.h"
#include "trustdb.h"
#include "i18n.h"
#include "keyserver-internal.h"
#include "call-agent.h"
#include "host2net.h"
#include "mbox-util.h"

#define MAX_PK_CACHE_ENTRIES   PK_UID_CACHE_SIZE
#define MAX_UID_CACHE_ENTRIES  PK_UID_CACHE_SIZE

#if MAX_PK_CACHE_ENTRIES < 2
#error We need the cache for key creation
#endif

struct getkey_ctx_s
{
  int exact;
  int want_secret;       /* The caller requested only secret keys.  */
  KBNODE keyblock;
  KBPOS kbpos;
  KBNODE found_key;      /* Pointer into some keyblock. */
  strlist_t extra_list;  /* Will be freed when releasing the context.  */
  int req_usage;
  KEYDB_HANDLE kr_handle;
  int not_allocated;
  int nitems;
  KEYDB_SEARCH_DESC items[1];
};

#if 0
static struct
{
  int any;
  int okay_count;
  int nokey_count;
  int error_count;
} lkup_stats[21];
#endif

typedef struct keyid_list
{
  struct keyid_list *next;
  char fpr[MAX_FINGERPRINT_LEN];
  u32 keyid[2];
} *keyid_list_t;


#if MAX_PK_CACHE_ENTRIES
typedef struct pk_cache_entry
{
  struct pk_cache_entry *next;
  u32 keyid[2];
  PKT_public_key *pk;
} *pk_cache_entry_t;
static pk_cache_entry_t pk_cache;
static int pk_cache_entries;    /* Number of entries in pk cache.  */
static int pk_cache_disabled;
#endif

#if MAX_UID_CACHE_ENTRIES < 5
#error we really need the userid cache
#endif
typedef struct user_id_db
{
  struct user_id_db *next;
  keyid_list_t keyids;
  int len;
  char name[1];
} *user_id_db_t;
static user_id_db_t user_id_db;
static int uid_cache_entries;   /* Number of entries in uid cache. */

static void merge_selfsigs (kbnode_t keyblock);
static int lookup (getkey_ctx_t ctx, kbnode_t *ret_keyblock, int want_secret);

#if 0
static void
print_stats ()
{
  int i;
  for (i = 0; i < DIM (lkup_stats); i++)
    {
      if (lkup_stats[i].any)
        es_fprintf (es_stderr,
                 "lookup stats: mode=%-2d  ok=%-6d  nokey=%-6d  err=%-6d\n",
                 i,
                 lkup_stats[i].okay_count,
                 lkup_stats[i].nokey_count, lkup_stats[i].error_count);
    }
}
#endif


void
cache_public_key (PKT_public_key * pk)
{
#if MAX_PK_CACHE_ENTRIES
  pk_cache_entry_t ce, ce2;
  u32 keyid[2];

  if (pk_cache_disabled)
    return;

  if (pk->flags.dont_cache)
    return;

  if (is_ELGAMAL (pk->pubkey_algo)
      || pk->pubkey_algo == PUBKEY_ALGO_DSA
      || pk->pubkey_algo == PUBKEY_ALGO_ECDSA
      || pk->pubkey_algo == PUBKEY_ALGO_EDDSA
      || pk->pubkey_algo == PUBKEY_ALGO_ECDH
      || is_RSA (pk->pubkey_algo))
    {
      keyid_from_pk (pk, keyid);
    }
  else
    return; /* Don't know how to get the keyid.  */

  for (ce = pk_cache; ce; ce = ce->next)
    if (ce->keyid[0] == keyid[0] && ce->keyid[1] == keyid[1])
      {
        if (DBG_CACHE)
          log_debug ("cache_public_key: already in cache\n");
        return;
      }

  if (pk_cache_entries >= MAX_PK_CACHE_ENTRIES)
    {
      int n;

      /* Remove the last 50% of the entries.  */
      for (ce = pk_cache, n = 0; ce && n < pk_cache_entries/2; n++)
        ce = ce->next;
      if (ce != pk_cache && ce->next)
        {
          ce2 = ce->next;
          ce->next = NULL;
          ce = ce2;
          for (; ce; ce = ce2)
            {
              ce2 = ce->next;
              free_public_key (ce->pk);
              xfree (ce);
              pk_cache_entries--;
            }
        }
      assert (pk_cache_entries < MAX_PK_CACHE_ENTRIES);
    }
  pk_cache_entries++;
  ce = xmalloc (sizeof *ce);
  ce->next = pk_cache;
  pk_cache = ce;
  ce->pk = copy_public_key (NULL, pk);
  ce->keyid[0] = keyid[0];
  ce->keyid[1] = keyid[1];
#endif
}


/* Return a const utf-8 string with the text "[User ID not found]".
   This function is required so that we don't need to switch gettext's
   encoding temporary.  */
static const char *
user_id_not_found_utf8 (void)
{
  static char *text;

  if (!text)
    text = native_to_utf8 (_("[User ID not found]"));
  return text;
}



/* Return the user ID from the given keyblock.
 * We use the primary uid flag which has been set by the merge_selfsigs
 * function.  The returned value is only valid as long as then given
 * keyblock is not changed.  */
static const char *
get_primary_uid (KBNODE keyblock, size_t * uidlen)
{
  KBNODE k;
  const char *s;

  for (k = keyblock; k; k = k->next)
    {
      if (k->pkt->pkttype == PKT_USER_ID
          && !k->pkt->pkt.user_id->attrib_data
          && k->pkt->pkt.user_id->is_primary)
        {
          *uidlen = k->pkt->pkt.user_id->len;
          return k->pkt->pkt.user_id->name;
        }
    }
  s = user_id_not_found_utf8 ();
  *uidlen = strlen (s);
  return s;
}


static void
release_keyid_list (keyid_list_t k)
{
  while (k)
    {
      keyid_list_t k2 = k->next;
      xfree (k);
      k = k2;
    }
}

/****************
 * Store the association of keyid and userid
 * Feed only public keys to this function.
 */
static void
cache_user_id (KBNODE keyblock)
{
  user_id_db_t r;
  const char *uid;
  size_t uidlen;
  keyid_list_t keyids = NULL;
  KBNODE k;

  for (k = keyblock; k; k = k->next)
    {
      if (k->pkt->pkttype == PKT_PUBLIC_KEY
          || k->pkt->pkttype == PKT_PUBLIC_SUBKEY)
        {
          keyid_list_t a = xmalloc_clear (sizeof *a);
          /* Hmmm: For a long list of keyids it might be an advantage
           * to append the keys.  */
          fingerprint_from_pk (k->pkt->pkt.public_key, a->fpr, NULL);
          keyid_from_pk (k->pkt->pkt.public_key, a->keyid);
          /* First check for duplicates.  */
          for (r = user_id_db; r; r = r->next)
            {
              keyid_list_t b = r->keyids;
              for (b = r->keyids; b; b = b->next)
                {
                  if (!memcmp (b->fpr, a->fpr, MAX_FINGERPRINT_LEN))
                    {
                      if (DBG_CACHE)
                        log_debug ("cache_user_id: already in cache\n");
                      release_keyid_list (keyids);
                      xfree (a);
                      return;
                    }
                }
            }
          /* Now put it into the cache.  */
          a->next = keyids;
          keyids = a;
        }
    }
  if (!keyids)
    BUG (); /* No key no fun.  */


  uid = get_primary_uid (keyblock, &uidlen);

  if (uid_cache_entries >= MAX_UID_CACHE_ENTRIES)
    {
      /* fixme: use another algorithm to free some cache slots */
      r = user_id_db;
      user_id_db = r->next;
      release_keyid_list (r->keyids);
      xfree (r);
      uid_cache_entries--;
    }
  r = xmalloc (sizeof *r + uidlen - 1);
  r->keyids = keyids;
  r->len = uidlen;
  memcpy (r->name, uid, r->len);
  r->next = user_id_db;
  user_id_db = r;
  uid_cache_entries++;
}


void
getkey_disable_caches ()
{
#if MAX_PK_CACHE_ENTRIES
  {
    pk_cache_entry_t ce, ce2;

    for (ce = pk_cache; ce; ce = ce2)
      {
        ce2 = ce->next;
        free_public_key (ce->pk);
        xfree (ce);
      }
    pk_cache_disabled = 1;
    pk_cache_entries = 0;
    pk_cache = NULL;
  }
#endif
  /* fixme: disable user id cache ? */
}


static void
pk_from_block (GETKEY_CTX ctx, PKT_public_key * pk, KBNODE keyblock)
{
  KBNODE a = ctx->found_key ? ctx->found_key : keyblock;

  assert (a->pkt->pkttype == PKT_PUBLIC_KEY
          || a->pkt->pkttype == PKT_PUBLIC_SUBKEY);

  copy_public_key (pk, a->pkt->pkt.public_key);
}

/* Get a public key and store it into the allocated pk can be called
 * with PK set to NULL to just read it into some internal
 * structures.  */
int
get_pubkey (PKT_public_key * pk, u32 * keyid)
{
  int internal = 0;
  int rc = 0;

#if MAX_PK_CACHE_ENTRIES
  if (pk)
    {
      /* Try to get it from the cache.  We don't do this when pk is
         NULL as it does not guarantee that the user IDs are
         cached. */
      pk_cache_entry_t ce;
      for (ce = pk_cache; ce; ce = ce->next)
        {
          if (ce->keyid[0] == keyid[0] && ce->keyid[1] == keyid[1])
            {
              copy_public_key (pk, ce->pk);
              return 0;
            }
        }
    }
#endif
  /* More init stuff.  */
  if (!pk)
    {
      pk = xmalloc_clear (sizeof *pk);
      internal++;
    }


  /* Do a lookup.  */
  {
    struct getkey_ctx_s ctx;
    KBNODE kb = NULL;
    memset (&ctx, 0, sizeof ctx);
    ctx.exact = 1; /* Use the key ID exactly as given.  */
    ctx.not_allocated = 1;
    ctx.kr_handle = keydb_new ();
    ctx.nitems = 1;
    ctx.items[0].mode = KEYDB_SEARCH_MODE_LONG_KID;
    ctx.items[0].u.kid[0] = keyid[0];
    ctx.items[0].u.kid[1] = keyid[1];
    ctx.req_usage = pk->req_usage;
    rc = lookup (&ctx, &kb, 0);
    if (!rc)
      {
        pk_from_block (&ctx, pk, kb);
      }
    get_pubkey_end (&ctx);
    release_kbnode (kb);
  }
  if (!rc)
    goto leave;

  rc = GPG_ERR_NO_PUBKEY;

leave:
  if (!rc)
    cache_public_key (pk);
  if (internal)
    free_public_key (pk);
  return rc;
}


/* Get a public key and store it into the allocated pk.  This function
   differs from get_pubkey() in that it does not do a check of the key
   to avoid recursion.  It should be used only in very certain cases.
   It will only retrieve primary keys.  */
int
get_pubkey_fast (PKT_public_key * pk, u32 * keyid)
{
  int rc = 0;
  KEYDB_HANDLE hd;
  KBNODE keyblock;
  u32 pkid[2];

  assert (pk);
#if MAX_PK_CACHE_ENTRIES
  {
    /* Try to get it from the cache */
    pk_cache_entry_t ce;

    for (ce = pk_cache; ce; ce = ce->next)
      {
        if (ce->keyid[0] == keyid[0] && ce->keyid[1] == keyid[1])
          {
            if (pk)
              copy_public_key (pk, ce->pk);
            return 0;
          }
      }
  }
#endif

  hd = keydb_new ();
  rc = keydb_search_kid (hd, keyid);
  if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
    {
      keydb_release (hd);
      return GPG_ERR_NO_PUBKEY;
    }
  rc = keydb_get_keyblock (hd, &keyblock);
  keydb_release (hd);
  if (rc)
    {
      log_error ("keydb_get_keyblock failed: %s\n", gpg_strerror (rc));
      return GPG_ERR_NO_PUBKEY;
    }

  assert (keyblock && keyblock->pkt
          && (keyblock->pkt->pkttype == PKT_PUBLIC_KEY
              || keyblock->pkt->pkttype == PKT_PUBLIC_SUBKEY));

  keyid_from_pk (keyblock->pkt->pkt.public_key, pkid);
  if (keyid[0] == pkid[0] && keyid[1] == pkid[1])
    copy_public_key (pk, keyblock->pkt->pkt.public_key);
  else
    rc = GPG_ERR_NO_PUBKEY;

  release_kbnode (keyblock);

  /* Not caching key here since it won't have all of the fields
     properly set. */

  return rc;
}


KBNODE
get_pubkeyblock (u32 * keyid)
{
  struct getkey_ctx_s ctx;
  int rc = 0;
  KBNODE keyblock = NULL;

  memset (&ctx, 0, sizeof ctx);
  /* No need to set exact here because we want the entire block.  */
  ctx.not_allocated = 1;
  ctx.kr_handle = keydb_new ();
  ctx.nitems = 1;
  ctx.items[0].mode = KEYDB_SEARCH_MODE_LONG_KID;
  ctx.items[0].u.kid[0] = keyid[0];
  ctx.items[0].u.kid[1] = keyid[1];
  rc = lookup (&ctx, &keyblock, 0);
  get_pubkey_end (&ctx);

  return rc ? NULL : keyblock;
}




/*
 * Get a public key and store it into PK.  This functions check that a
 * corresponding secret key is available.  With no secret key it does
 * not succeeed.
 */
gpg_error_t
get_seckey (PKT_public_key *pk, u32 *keyid)
{
  gpg_error_t err;
  struct getkey_ctx_s ctx;
  kbnode_t keyblock = NULL;

  memset (&ctx, 0, sizeof ctx);
  ctx.exact = 1; /* Use the key ID exactly as given.  */
  ctx.not_allocated = 1;
  ctx.kr_handle = keydb_new ();
  ctx.nitems = 1;
  ctx.items[0].mode = KEYDB_SEARCH_MODE_LONG_KID;
  ctx.items[0].u.kid[0] = keyid[0];
  ctx.items[0].u.kid[1] = keyid[1];
  ctx.req_usage = pk->req_usage;
  err = lookup (&ctx, &keyblock, 1);
  if (!err)
    {
      pk_from_block (&ctx, pk, keyblock);
    }
  get_pubkey_end (&ctx);
  release_kbnode (keyblock);

  if (!err)
    err = agent_probe_secret_key (/*ctrl*/NULL, pk);

  return err;
}


static int
skip_unusable (void *dummy, u32 * keyid, PKT_user_id * uid)
{
  int unusable = 0;
  KBNODE keyblock;

  (void) dummy;

  keyblock = get_pubkeyblock (keyid);
  if (!keyblock)
    {
      log_error ("error checking usability status of %s\n", keystr (keyid));
      goto leave;
    }

  /* Is the user ID in question revoked/expired? */
  if (uid)
    {
      KBNODE node;

      for (node = keyblock; node; node = node->next)
        {
          if (node->pkt->pkttype == PKT_USER_ID)
            {
              if (cmp_user_ids (uid, node->pkt->pkt.user_id) == 0
                  && (node->pkt->pkt.user_id->is_revoked
                      || node->pkt->pkt.user_id->is_expired))
                {
                  unusable = 1;
                  break;
                }
            }
        }
    }

  if (!unusable)
    unusable = pk_is_disabled (keyblock->pkt->pkt.public_key);

leave:
  release_kbnode (keyblock);
  return unusable;
}


/* Try to get the pubkey by the userid.  This function looks for the
 * first pubkey certificate which has the given name in a user_id.  If
 * PK has the pubkey algo set, the function will only return a pubkey
 * with that algo.  If NAMELIST is NULL, the first key is returned.
 * The caller should provide storage for the PK or pass NULL if it is
 * not needed.  If RET_KB is not NULL the function stores the entire
 * keyblock at that address.  */
static int
key_byname (GETKEY_CTX *retctx, strlist_t namelist,
            PKT_public_key *pk,
            int want_secret, int include_unusable,
            KBNODE * ret_kb, KEYDB_HANDLE * ret_kdbhd)
{
  int rc = 0;
  int n;
  strlist_t r;
  GETKEY_CTX ctx;
  KBNODE help_kb = NULL;

  if (retctx)
    {
      /* Reset the returned context in case of error.  */
      assert (!ret_kdbhd); /* Not allowed because the handle is stored
                              in the context.  */
      *retctx = NULL;
    }
  if (ret_kdbhd)
    *ret_kdbhd = NULL;

  if (!namelist)
    {
      ctx = xmalloc_clear (sizeof *ctx);
      ctx->nitems = 1;
      ctx->items[0].mode = KEYDB_SEARCH_MODE_FIRST;
      if (!include_unusable)
        ctx->items[0].skipfnc = skip_unusable;
    }
  else
    {
      /* Build the search context.  */
      for (n = 0, r = namelist; r; r = r->next)
        n++;

      ctx = xmalloc_clear (sizeof *ctx + (n - 1) * sizeof ctx->items);
      ctx->nitems = n;

      for (n = 0, r = namelist; r; r = r->next, n++)
        {
          gpg_error_t err;

          err = classify_user_id (r->d, &ctx->items[n], 1);

          if (ctx->items[n].exact)
            ctx->exact = 1;
          if (err)
            {
              xfree (ctx);
              return gpg_err_code (err); /* FIXME: remove gpg_err_code.  */
            }
          if (!include_unusable
              && ctx->items[n].mode != KEYDB_SEARCH_MODE_SHORT_KID
              && ctx->items[n].mode != KEYDB_SEARCH_MODE_LONG_KID
              && ctx->items[n].mode != KEYDB_SEARCH_MODE_FPR16
              && ctx->items[n].mode != KEYDB_SEARCH_MODE_FPR20
              && ctx->items[n].mode != KEYDB_SEARCH_MODE_FPR)
            ctx->items[n].skipfnc = skip_unusable;
        }
    }

  ctx->want_secret = want_secret;
  ctx->kr_handle = keydb_new ();
  if (!ret_kb)
    ret_kb = &help_kb;

  if (pk)
    {
      ctx->req_usage = pk->req_usage;
    }

  rc = lookup (ctx, ret_kb, want_secret);
  if (!rc && pk)
    {
      pk_from_block (ctx, pk, *ret_kb);
    }

  release_kbnode (help_kb);

  if (retctx) /* Caller wants the context.  */
    *retctx = ctx;
  else
    {
      if (ret_kdbhd)
        {
          *ret_kdbhd = ctx->kr_handle;
          ctx->kr_handle = NULL;
        }
      get_pubkey_end (ctx);
    }

  return rc;
}



/* Find a public key from NAME and return the keyblock or the key.  If
   ret_kdb is not NULL, the KEYDB handle used to locate this keyblock
   is returned and the caller is responsible for closing it.  If a key
   was not found (or if local search has been disabled) and NAME is a
   valid RFC822 mailbox and --auto-key-locate has been enabled, we try
   to import the key via the online mechanisms defined by
   --auto-key-locate.  */
int
get_pubkey_byname (ctrl_t ctrl, GETKEY_CTX * retctx, PKT_public_key * pk,
                   const char *name, KBNODE * ret_keyblock,
                   KEYDB_HANDLE * ret_kdbhd, int include_unusable, int no_akl)
{
  int rc;
  strlist_t namelist = NULL;
  struct akl *akl;
  int is_mbox;
  int nodefault = 0;
  int anylocalfirst = 0;

  if (retctx)
    *retctx = NULL;

  is_mbox = is_valid_mailbox (name);

  /* Check whether the default local search has been disabled.
     This is the case if either the "nodefault" or the "local" keyword
     are in the list of auto key locate mechanisms.

     ANYLOCALFIRST is set if the search order has the local method
     before any other or if "local" is used first by default.  This
     makes sure that if a RETCTX is used it is only set if a local
     search has precedence over the other search methods and only then
     a followup call to get_pubkey_next shall succeed.  */
  if (!no_akl)
    {
      for (akl = opt.auto_key_locate; akl; akl = akl->next)
        if (akl->type == AKL_NODEFAULT || akl->type == AKL_LOCAL)
          {
            nodefault = 1;
            break;
          }
      for (akl = opt.auto_key_locate; akl; akl = akl->next)
        if (akl->type != AKL_NODEFAULT)
          {
            if (akl->type == AKL_LOCAL)
              anylocalfirst = 1;
            break;
          }
    }

  if (!nodefault)
    anylocalfirst = 1;

  if (nodefault && is_mbox)
    {
      /* Nodefault but a mailbox - let the AKL locate the key.  */
      rc = GPG_ERR_NO_PUBKEY;
    }
  else
    {
      add_to_strlist (&namelist, name);
      rc = key_byname (retctx, namelist, pk, 0,
                       include_unusable, ret_keyblock, ret_kdbhd);
    }

  /* If the requested name resembles a valid mailbox and automatic
     retrieval has been enabled, we try to import the key. */
  if (gpg_err_code (rc) == GPG_ERR_NO_PUBKEY && !no_akl && is_mbox)
    {
      for (akl = opt.auto_key_locate; akl; akl = akl->next)
        {
          unsigned char *fpr = NULL;
          size_t fpr_len;
          int did_key_byname = 0;
          int no_fingerprint = 0;
          const char *mechanism = "?";

          switch (akl->type)
            {
            case AKL_NODEFAULT:
              /* This is a dummy mechanism.  */
              mechanism = "None";
              rc = GPG_ERR_NO_PUBKEY;
              break;

            case AKL_LOCAL:
              mechanism = "Local";
              did_key_byname = 1;
              if (retctx)
                {
                  get_pubkey_end (*retctx);
                  *retctx = NULL;
                }
              add_to_strlist (&namelist, name);
              rc = key_byname (anylocalfirst ? retctx : NULL,
                               namelist, pk, 0,
                               include_unusable, ret_keyblock, ret_kdbhd);
              break;

            case AKL_CERT:
              mechanism = "DNS CERT";
              glo_ctrl.in_auto_key_retrieve++;
              rc = keyserver_import_cert (ctrl, name, &fpr, &fpr_len);
              glo_ctrl.in_auto_key_retrieve--;
              break;

            case AKL_PKA:
              mechanism = "PKA";
              glo_ctrl.in_auto_key_retrieve++;
              rc = keyserver_import_pka (ctrl, name, &fpr, &fpr_len);
              glo_ctrl.in_auto_key_retrieve--;
              break;

            case AKL_LDAP:
              mechanism = "LDAP";
              glo_ctrl.in_auto_key_retrieve++;
              rc = keyserver_import_ldap (ctrl, name, &fpr, &fpr_len);
              glo_ctrl.in_auto_key_retrieve--;
              break;

            case AKL_KEYSERVER:
              /* Strictly speaking, we don't need to only use a valid
                 mailbox for the getname search, but it helps cut down
                 on the problem of searching for something like "john"
                 and getting a whole lot of keys back. */
              if (opt.keyserver)
                {
                  mechanism = opt.keyserver->uri;
                  glo_ctrl.in_auto_key_retrieve++;
                  rc = keyserver_import_name (ctrl, name, &fpr, &fpr_len,
                                              opt.keyserver);
                  glo_ctrl.in_auto_key_retrieve--;
                }
              else
                {
                  mechanism = "Unconfigured keyserver";
                  rc = GPG_ERR_NO_PUBKEY;
                }
              break;

            case AKL_SPEC:
              {
                struct keyserver_spec *keyserver;

                mechanism = akl->spec->uri;
                keyserver = keyserver_match (akl->spec);
                glo_ctrl.in_auto_key_retrieve++;
                rc = keyserver_import_name (ctrl,
                                            name, &fpr, &fpr_len, keyserver);
                glo_ctrl.in_auto_key_retrieve--;
              }
              break;
            }

          /* Use the fingerprint of the key that we actually fetched.
             This helps prevent problems where the key that we fetched
             doesn't have the same name that we used to fetch it.  In
             the case of CERT and PKA, this is an actual security
             requirement as the URL might point to a key put in by an
             attacker.  By forcing the use of the fingerprint, we
             won't use the attacker's key here. */
          if (!rc && fpr)
            {
              char fpr_string[MAX_FINGERPRINT_LEN * 2 + 1];

              assert (fpr_len <= MAX_FINGERPRINT_LEN);

              free_strlist (namelist);
              namelist = NULL;

              bin2hex (fpr, fpr_len, fpr_string);

              if (opt.verbose)
                log_info ("auto-key-locate found fingerprint %s\n",
                          fpr_string);

              add_to_strlist (&namelist, fpr_string);
            }
          else if (!rc && !fpr && !did_key_byname)
            {
              no_fingerprint = 1;
              rc = GPG_ERR_NO_PUBKEY;
            }
          xfree (fpr);
          fpr = NULL;

          if (!rc && !did_key_byname)
            {
              if (retctx)
                {
                  get_pubkey_end (*retctx);
                  *retctx = NULL;
                }
              rc = key_byname (anylocalfirst ? retctx : NULL,
                               namelist, pk, 0,
                               include_unusable, ret_keyblock, ret_kdbhd);
            }
          if (!rc)
            {
              /* Key found.  */
              log_info (_("automatically retrieved '%s' via %s\n"),
                        name, mechanism);
              break;
            }
          if (gpg_err_code (rc) != GPG_ERR_NO_PUBKEY
              || opt.verbose || no_fingerprint)
            log_info (_("error retrieving '%s' via %s: %s\n"),
                      name, mechanism,
                      no_fingerprint ? _("No fingerprint") : gpg_strerror (rc));
        }
    }


  if (rc && retctx)
    {
      get_pubkey_end (*retctx);
      *retctx = NULL;
    }

  if (retctx && *retctx)
    {
      assert (!(*retctx)->extra_list);
      (*retctx)->extra_list = namelist;
    }
  else
    free_strlist (namelist);
  return rc;
}


int
get_pubkey_bynames (GETKEY_CTX * retctx, PKT_public_key * pk,
                    strlist_t names, KBNODE * ret_keyblock)
{
  return key_byname (retctx, names, pk, 0, 1, ret_keyblock, NULL);
}

int
get_pubkey_next (GETKEY_CTX ctx, PKT_public_key * pk, KBNODE * ret_keyblock)
{
  return gpg_err_code (getkey_next (ctx, pk, ret_keyblock));
}

void
get_pubkey_end (GETKEY_CTX ctx)
{
  getkey_end (ctx);
}


/* Search for a key with the given standard fingerprint.  In contrast
 * to get_pubkey_byfprint we assume a right padded fingerprint of the
 * standard length.  PK may be NULL to only put the result into the
 * internal caches.  */
gpg_error_t
get_pubkey_byfpr (PKT_public_key *pk, const byte *fpr)
{
  gpg_error_t err;
  struct getkey_ctx_s ctx;
  kbnode_t kb = NULL;

  memset (&ctx, 0, sizeof ctx);
  ctx.exact = 1;
  ctx.not_allocated = 1;
  ctx.kr_handle = keydb_new ();
  ctx.nitems = 1;
  ctx.items[0].mode = KEYDB_SEARCH_MODE_FPR;
  memcpy (ctx.items[0].u.fpr, fpr, MAX_FINGERPRINT_LEN);
  err = lookup (&ctx, &kb, 0);
  if (!err && pk)
    pk_from_block (&ctx, pk, kb);
  release_kbnode (kb);
  get_pubkey_end (&ctx);

  return err;
}


/* Search for a key with the given fingerprint.  The caller need to
 * prove an allocated public key object at PK.  If R_KEYBLOCK is not
 * NULL the entire keyblock is stored there and the caller needs to
 * call release_kbnode() on it.  Note that this function does an exact
 * search and thus the public key stored at PK may be a copy of a
 * subkey.
 *
 * FIXME:
 * We should replace this with the _byname function.  This can be done
 * by creating a userID conforming to the unified fingerprint style.
 */
int
get_pubkey_byfprint (PKT_public_key *pk, kbnode_t *r_keyblock,
                     const byte * fprint, size_t fprint_len)
{
  int rc;

  if (r_keyblock)
    *r_keyblock = NULL;

  if (fprint_len == 20 || fprint_len == 16)
    {
      struct getkey_ctx_s ctx;
      KBNODE kb = NULL;

      memset (&ctx, 0, sizeof ctx);
      ctx.exact = 1;
      ctx.not_allocated = 1;
      ctx.kr_handle = keydb_new ();
      ctx.nitems = 1;
      ctx.items[0].mode = fprint_len == 16 ? KEYDB_SEARCH_MODE_FPR16
        : KEYDB_SEARCH_MODE_FPR20;
      memcpy (ctx.items[0].u.fpr, fprint, fprint_len);
      rc = lookup (&ctx, &kb, 0);
      if (!rc && pk)
        {
          pk_from_block (&ctx, pk, kb);
          if (r_keyblock)
            {
              *r_keyblock = kb;
              kb = NULL;
            }
        }
      release_kbnode (kb);
      get_pubkey_end (&ctx);
    }
  else
    rc = GPG_ERR_GENERAL; /* Oops */
  return rc;
}


/* Get a public key and store it into the allocated pk.  This function
   differs from get_pubkey_byfprint() in that it does not do a check
   of the key to avoid recursion.  It should be used only in very
   certain cases.  PK may be NULL to check just for the existance of
   the key.  */
int
get_pubkey_byfprint_fast (PKT_public_key * pk,
                          const byte * fprint, size_t fprint_len)
{
  int rc = 0;
  KEYDB_HANDLE hd;
  KBNODE keyblock;
  byte fprbuf[MAX_FINGERPRINT_LEN];
  int i;

  for (i = 0; i < MAX_FINGERPRINT_LEN && i < fprint_len; i++)
    fprbuf[i] = fprint[i];
  while (i < MAX_FINGERPRINT_LEN)
    fprbuf[i++] = 0;

  hd = keydb_new ();
  rc = keydb_search_fpr (hd, fprbuf);
  if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
    {
      keydb_release (hd);
      return GPG_ERR_NO_PUBKEY;
    }
  rc = keydb_get_keyblock (hd, &keyblock);
  keydb_release (hd);
  if (rc)
    {
      log_error ("keydb_get_keyblock failed: %s\n", gpg_strerror (rc));
      return GPG_ERR_NO_PUBKEY;
    }

  assert (keyblock->pkt->pkttype == PKT_PUBLIC_KEY
          || keyblock->pkt->pkttype == PKT_PUBLIC_SUBKEY);
  if (pk)
    copy_public_key (pk, keyblock->pkt->pkt.public_key);
  release_kbnode (keyblock);

  /* Not caching key here since it won't have all of the fields
     properly set. */

  return 0;
}


/* Search for a key with the given fingerprint and return the
 * complete keyblock which may have more than only this key.   */
int
get_keyblock_byfprint (KBNODE * ret_keyblock, const byte * fprint,
                       size_t fprint_len)
{
  int rc;

  if (fprint_len == 20 || fprint_len == 16)
    {
      struct getkey_ctx_s ctx;

      memset (&ctx, 0, sizeof ctx);
      ctx.not_allocated = 1;
      ctx.kr_handle = keydb_new ();
      ctx.nitems = 1;
      ctx.items[0].mode = (fprint_len == 16
                           ? KEYDB_SEARCH_MODE_FPR16
                           : KEYDB_SEARCH_MODE_FPR20);
      memcpy (ctx.items[0].u.fpr, fprint, fprint_len);
      rc = lookup (&ctx, ret_keyblock, 0);
      get_pubkey_end (&ctx);
    }
  else
    rc = GPG_ERR_GENERAL; /* Oops */

  return rc;
}


/* Get a secret key by NAME and store it into PK.  If NAME is NULL use
 * the default key.  This functions checks that a corresponding secret
 * key is available.  With no secret key it does not succeeed. */
gpg_error_t
get_seckey_byname (PKT_public_key *pk, const char *name)
{
  gpg_error_t err;
  strlist_t namelist = NULL;
  int include_unusable = 1;

  /* If we have no name, try to use the default secret key.  If we
     have no default, we'll use the first usable one. */

  if (!name && opt.def_secret_key && *opt.def_secret_key)
    add_to_strlist (&namelist, opt.def_secret_key);
  else if (name)
    add_to_strlist (&namelist, name);
  else
    include_unusable = 0;

  err = key_byname (NULL, namelist, pk, 1, include_unusable, NULL, NULL);

  free_strlist (namelist);

  return err;
}



/* Search for a key with the given fingerprint.
 * FIXME:
 * We should replace this with the _byname function.  This can be done
 * by creating a userID conforming to the unified fingerprint style.   */
gpg_error_t
get_seckey_byfprint (PKT_public_key *pk, const byte * fprint, size_t fprint_len)
{
  gpg_error_t err;

  if (fprint_len == 20 || fprint_len == 16)
    {
      struct getkey_ctx_s ctx;
      kbnode_t kb = NULL;

      memset (&ctx, 0, sizeof ctx);
      ctx.exact = 1;
      ctx.not_allocated = 1;
      ctx.kr_handle = keydb_new ();
      ctx.nitems = 1;
      ctx.items[0].mode = fprint_len == 16 ? KEYDB_SEARCH_MODE_FPR16
        : KEYDB_SEARCH_MODE_FPR20;
      memcpy (ctx.items[0].u.fpr, fprint, fprint_len);
      err = lookup (&ctx, &kb, 1);
      if (!err && pk)
        pk_from_block (&ctx, pk, kb);
      release_kbnode (kb);
      get_pubkey_end (&ctx);
    }
  else
    err = gpg_error (GPG_ERR_BUG);
  return err;
}


/* Search for a secret key with the given fingerprint and return the
   complete keyblock which may have more than only this key.  Return
   an error if no corresponding secret key is available.  */
gpg_error_t
get_seckeyblock_byfprint (kbnode_t *ret_keyblock,
                          const byte *fprint, size_t fprint_len)
{
  gpg_error_t err;
  struct getkey_ctx_s ctx;

  if (fprint_len != 20 && fprint_len == 16)
    return gpg_error (GPG_ERR_BUG);

  memset (&ctx, 0, sizeof ctx);
  ctx.not_allocated = 1;
  ctx.kr_handle = keydb_new ();
  ctx.nitems = 1;
  ctx.items[0].mode = (fprint_len == 16
                       ? KEYDB_SEARCH_MODE_FPR16 : KEYDB_SEARCH_MODE_FPR20);
  memcpy (ctx.items[0].u.fpr, fprint, fprint_len);
  err = lookup (&ctx, ret_keyblock, 1);
  get_pubkey_end (&ctx);

  return err;
}


\f
/* The new function to return a key.
   FIXME: Document it.  */
gpg_error_t
getkey_bynames (getkey_ctx_t *retctx, PKT_public_key *pk,
                strlist_t names, int want_secret, kbnode_t *ret_keyblock)
{
  return key_byname (retctx, names, pk, want_secret, 1,
                     ret_keyblock, NULL);
}


/* Get a key by name and store it into PK if that is not NULL.  If
 * RETCTX is not NULL return the search context which needs to be
 * released by the caller using getkey_end.  If NAME is NULL use the
 * default key (see below).  On success and if RET_KEYBLOCK is not
 * NULL the found keyblock is stored at this address.  WANT_SECRET
 * passed as true requires that a secret key is available for the
 * selected key.
 *
 * If WANT_SECRET is true and NAME is NULL and a default key has been
 * defined that defined key is used.  In all other cases the first
 * available key is used.
 *
 * FIXME: Explain what is up with unusable keys.
 *
 * FIXME: We also have the get_pubkey_byname function which has a
 * different semantic.  Should be merged with this one.
 */
gpg_error_t
getkey_byname (getkey_ctx_t *retctx, PKT_public_key *pk,
               const char *name, int want_secret, kbnode_t *ret_keyblock)
{
  gpg_error_t err;
  strlist_t namelist = NULL;
  int with_unusable = 1;

  if (want_secret && !name && opt.def_secret_key && *opt.def_secret_key)
    add_to_strlist (&namelist, opt.def_secret_key);
  else if (name)
    add_to_strlist (&namelist, name);
  else
    with_unusable = 0;

  err = key_byname (retctx, namelist, pk, want_secret, with_unusable,
                    ret_keyblock, NULL);

  /* FIXME: Check that we really return GPG_ERR_NO_SECKEY if
     WANT_SECRET has been used.  */

  free_strlist (namelist);

  return err;
}


/* The new function to return the next key.  */
gpg_error_t
getkey_next (getkey_ctx_t ctx, PKT_public_key *pk, kbnode_t *ret_keyblock)
{
  int rc; /* Fixme:  Make sure this is proper gpg_error */

  /* We need to disable the caching so that for an exact key search we
     won't get the result back from the cache and thus end up in an
     endless loop.  Disabling this here is sufficient because although
     the result has been cached, if won't be used then.  */
  keydb_disable_caching (ctx->kr_handle);

  rc = lookup (ctx, ret_keyblock, ctx->want_secret);
  if (!rc && pk && ret_keyblock)
    pk_from_block (ctx, pk, *ret_keyblock);

  return rc;
}


/* The new function to finish a key listing.  */
void
getkey_end (getkey_ctx_t ctx)
{
  if (ctx)
    {
      memset (&ctx->kbpos, 0, sizeof ctx->kbpos);
      keydb_release (ctx->kr_handle);
      free_strlist (ctx->extra_list);
      if (!ctx->not_allocated)
        xfree (ctx);
    }
}


\f
/************************************************
 ************* Merging stuff ********************
 ************************************************/

/* Set the mainkey_id fields for all keys in KEYBLOCK.  This is
   usually done by merge_selfsigs but at some places we only need the
   main_kid but the the full merging.  The function also guarantees
   that all pk->keyids are computed. */
void
setup_main_keyids (kbnode_t keyblock)
{
  u32 kid[2], mainkid[2];
  kbnode_t kbctx, node;
  PKT_public_key *pk;

  if (keyblock->pkt->pkttype != PKT_PUBLIC_KEY)
    BUG ();
  pk = keyblock->pkt->pkt.public_key;

  keyid_from_pk (pk, mainkid);
  for (kbctx=NULL; (node = walk_kbnode (keyblock, &kbctx, 0)); )
    {
      if (!(node->pkt->pkttype == PKT_PUBLIC_KEY
            || node->pkt->pkttype == PKT_PUBLIC_SUBKEY))
        continue;
      pk = node->pkt->pkt.public_key;
      keyid_from_pk (pk, kid); /* Make sure pk->keyid is set.  */
      if (!pk->main_keyid[0] && !pk->main_keyid[1])
        {
          pk->main_keyid[0] = mainkid[0];
          pk->main_keyid[1] = mainkid[1];
        }
    }
}


/* Merge all self-signatures with the keys.  */
void
merge_keys_and_selfsig (KBNODE keyblock)
{
  if (!keyblock)
    ;
  else if (keyblock->pkt->pkttype == PKT_PUBLIC_KEY)
    merge_selfsigs (keyblock);
  else
    log_debug ("FIXME: merging secret key blocks is not anymore available\n");
}


static int
parse_key_usage (PKT_signature * sig)
{
  int key_usage = 0;
  const byte *p;
  size_t n;
  byte flags;

  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_KEY_FLAGS, &n);
  if (p && n)
    {
      /* First octet of the keyflags.  */
      flags = *p;

      if (flags & 1)
        {
          key_usage |= PUBKEY_USAGE_CERT;
          flags &= ~1;
        }

      if (flags & 2)
        {
          key_usage |= PUBKEY_USAGE_SIG;
          flags &= ~2;
        }

      /* We do not distinguish between encrypting communications and
         encrypting storage. */
      if (flags & (0x04 | 0x08))
        {
          key_usage |= PUBKEY_USAGE_ENC;
          flags &= ~(0x04 | 0x08);
        }

      if (flags & 0x20)
        {
          key_usage |= PUBKEY_USAGE_AUTH;
          flags &= ~0x20;
        }

      if (flags)
        key_usage |= PUBKEY_USAGE_UNKNOWN;

      if (!key_usage)
        key_usage |= PUBKEY_USAGE_NONE;
    }
  else if (p) /* Key flags of length zero.  */
    key_usage |= PUBKEY_USAGE_NONE;

  /* We set PUBKEY_USAGE_UNKNOWN to indicate that this key has a
     capability that we do not handle.  This serves to distinguish
     between a zero key usage which we handle as the default
     capabilities for that algorithm, and a usage that we do not
     handle.  Likewise we use PUBKEY_USAGE_NONE to indicate that
     key_flags have been given but they do not specify any usage.  */

  return key_usage;
}


/* Apply information from SIGNODE (which is the valid self-signature
 * associated with that UID) to the UIDNODE:
 * - wether the UID has been revoked
 * - assumed creation date of the UID
 * - temporary store the keyflags here
 * - temporary store the key expiration time here
 * - mark whether the primary user ID flag hat been set.
 * - store the preferences
 */
static void
fixup_uidnode (KBNODE uidnode, KBNODE signode, u32 keycreated)
{
  PKT_user_id *uid = uidnode->pkt->pkt.user_id;
  PKT_signature *sig = signode->pkt->pkt.signature;
  const byte *p, *sym, *hash, *zip;
  size_t n, nsym, nhash, nzip;

  sig->flags.chosen_selfsig = 1;/* We chose this one. */
  uid->created = 0;             /* Not created == invalid. */
  if (IS_UID_REV (sig))
    {
      uid->is_revoked = 1;
      return; /* Has been revoked.  */
    }
  else
    uid->is_revoked = 0;

  uid->expiredate = sig->expiredate;

  if (sig->flags.expired)
    {
      uid->is_expired = 1;
      return; /* Has expired.  */
    }
  else
    uid->is_expired = 0;

  uid->created = sig->timestamp; /* This one is okay. */
  uid->selfsigversion = sig->version;
  /* If we got this far, it's not expired :) */
  uid->is_expired = 0;

  /* Store the key flags in the helper variable for later processing.  */
  uid->help_key_usage = parse_key_usage (sig);

  /* Ditto for the key expiration.  */
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_KEY_EXPIRE, NULL);
  if (p && buf32_to_u32 (p))
    uid->help_key_expire = keycreated + buf32_to_u32 (p);
  else
    uid->help_key_expire = 0;

  /* Set the primary user ID flag - we will later wipe out some
   * of them to only have one in our keyblock.  */
  uid->is_primary = 0;
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_PRIMARY_UID, NULL);
  if (p && *p)
    uid->is_primary = 2;

  /* We could also query this from the unhashed area if it is not in
   * the hased area and then later try to decide which is the better
   * there should be no security problem with this.
   * For now we only look at the hashed one.  */

  /* Now build the preferences list.  These must come from the
     hashed section so nobody can modify the ciphers a key is
     willing to accept.  */
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_PREF_SYM, &n);
  sym = p;
  nsym = p ? n : 0;
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_PREF_HASH, &n);
  hash = p;
  nhash = p ? n : 0;
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_PREF_COMPR, &n);
  zip = p;
  nzip = p ? n : 0;
  if (uid->prefs)
    xfree (uid->prefs);
  n = nsym + nhash + nzip;
  if (!n)
    uid->prefs = NULL;
  else
    {
      uid->prefs = xmalloc (sizeof (*uid->prefs) * (n + 1));
      n = 0;
      for (; nsym; nsym--, n++)
        {
          uid->prefs[n].type = PREFTYPE_SYM;
          uid->prefs[n].value = *sym++;
        }
      for (; nhash; nhash--, n++)
        {
          uid->prefs[n].type = PREFTYPE_HASH;
          uid->prefs[n].value = *hash++;
        }
      for (; nzip; nzip--, n++)
        {
          uid->prefs[n].type = PREFTYPE_ZIP;
          uid->prefs[n].value = *zip++;
        }
      uid->prefs[n].type = PREFTYPE_NONE; /* End of list marker  */
      uid->prefs[n].value = 0;
    }

  /* See whether we have the MDC feature.  */
  uid->flags.mdc = 0;
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_FEATURES, &n);
  if (p && n && (p[0] & 0x01))
    uid->flags.mdc = 1;

  /* And the keyserver modify flag.  */
  uid->flags.ks_modify = 1;
  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_KS_FLAGS, &n);
  if (p && n && (p[0] & 0x80))
    uid->flags.ks_modify = 0;
}

static void
sig_to_revoke_info (PKT_signature * sig, struct revoke_info *rinfo)
{
  rinfo->date = sig->timestamp;
  rinfo->algo = sig->pubkey_algo;
  rinfo->keyid[0] = sig->keyid[0];
  rinfo->keyid[1] = sig->keyid[1];
}


/* Note that R_REVOKED may be set to 0, 1 or 2.  */
static void
merge_selfsigs_main (KBNODE keyblock, int *r_revoked,
                     struct revoke_info *rinfo)
{
  PKT_public_key *pk = NULL;
  KBNODE k;
  u32 kid[2];
  u32 sigdate, uiddate, uiddate2;
  KBNODE signode, uidnode, uidnode2;
  u32 curtime = make_timestamp ();
  unsigned int key_usage = 0;
  u32 keytimestamp = 0;
  u32 key_expire = 0;
  int key_expire_seen = 0;
  byte sigversion = 0;

  *r_revoked = 0;
  memset (rinfo, 0, sizeof (*rinfo));

  if (keyblock->pkt->pkttype != PKT_PUBLIC_KEY)
    BUG ();
  pk = keyblock->pkt->pkt.public_key;
  keytimestamp = pk->timestamp;

  keyid_from_pk (pk, kid);
  pk->main_keyid[0] = kid[0];
  pk->main_keyid[1] = kid[1];

  if (pk->version < 4)
    {
      /* Before v4 the key packet itself contains the expiration date
       * and there was no way to change it, so we start with the one
       * from the key packet.  */
      key_expire = pk->max_expiredate;
      key_expire_seen = 1;
    }

  /* First pass: Find the latest direct key self-signature.  We assume
   * that the newest one overrides all others.  */

  /* In case this key was already merged. */
  xfree (pk->revkey);
  pk->revkey = NULL;
  pk->numrevkeys = 0;

  signode = NULL;
  sigdate = 0; /* Helper variable to find the latest signature.  */
  for (k = keyblock; k && k->pkt->pkttype != PKT_USER_ID; k = k->next)
    {
      if (k->pkt->pkttype == PKT_SIGNATURE)
        {
          PKT_signature *sig = k->pkt->pkt.signature;
          if (sig->keyid[0] == kid[0] && sig->keyid[1] == kid[1])
            {
              if (check_key_signature (keyblock, k, NULL))
                ; /* Signature did not verify.  */
              else if (IS_KEY_REV (sig))
                {
                  /* Key has been revoked - there is no way to
                   * override such a revocation, so we theoretically
                   * can stop now.  We should not cope with expiration
                   * times for revocations here because we have to
                   * assume that an attacker can generate all kinds of
                   * signatures.  However due to the fact that the key
                   * has been revoked it does not harm either and by
                   * continuing we gather some more info on that
                   * key.  */
                  *r_revoked = 1;
                  sig_to_revoke_info (sig, rinfo);
                }
              else if (IS_KEY_SIG (sig))
                {
                  /* Add any revocation keys onto the pk.  This is
                     particularly interesting since we normally only
                     get data from the most recent 1F signature, but
                     you need multiple 1F sigs to properly handle
                     revocation keys (PGP does it this way, and a
                     revocation key could be sensitive and hence in a
                     different signature). */
                  if (sig->revkey)
                    {
                      int i;

                      pk->revkey =
                        xrealloc (pk->revkey, sizeof (struct revocation_key) *
                                  (pk->numrevkeys + sig->numrevkeys));

                      for (i = 0; i < sig->numrevkeys; i++)
                        memcpy (&pk->revkey[pk->numrevkeys++],
                                &sig->revkey[i],
                                sizeof (struct revocation_key));
                    }

                  if (sig->timestamp >= sigdate)
                    {
                      if (sig->flags.expired)
                        ; /* Signature has expired - ignore it.  */
                      else
                        {
                          sigdate = sig->timestamp;
                          signode = k;
                          if (sig->version > sigversion)
                            sigversion = sig->version;

                        }
                    }
                }
            }
        }
    }

  /* Remove dupes from the revocation keys.  */

  if (pk->revkey)
    {
      int i, j, x, changed = 0;

      for (i = 0; i < pk->numrevkeys; i++)
        {
          for (j = i + 1; j < pk->numrevkeys; j++)
            {
              if (memcmp (&pk->revkey[i], &pk->revkey[j],
                          sizeof (struct revocation_key)) == 0)
                {
                  /* remove j */

                  for (x = j; x < pk->numrevkeys - 1; x++)
                    pk->revkey[x] = pk->revkey[x + 1];

                  pk->numrevkeys--;
                  j--;
                  changed = 1;
                }
            }
        }

      if (changed)
        pk->revkey = xrealloc (pk->revkey,
                               pk->numrevkeys *
                               sizeof (struct revocation_key));
    }

  if (signode)
    {
      /* Some information from a direct key signature take precedence
       * over the same information given in UID sigs.  */
      PKT_signature *sig = signode->pkt->pkt.signature;
      const byte *p;

      key_usage = parse_key_usage (sig);

      p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_KEY_EXPIRE, NULL);
      if (p && buf32_to_u32 (p))
        {
          key_expire = keytimestamp + buf32_to_u32 (p);
          key_expire_seen = 1;
        }

      /* Mark that key as valid: One direct key signature should
       * render a key as valid.  */
      pk->flags.valid = 1;
    }

  /* Pass 1.5: Look for key revocation signatures that were not made
     by the key (i.e. did a revocation key issue a revocation for
     us?).  Only bother to do this if there is a revocation key in the
     first place and we're not revoked already.  */

  if (!*r_revoked && pk->revkey)
    for (k = keyblock; k && k->pkt->pkttype != PKT_USER_ID; k = k->next)
      {
        if (k->pkt->pkttype == PKT_SIGNATURE)
          {
            PKT_signature *sig = k->pkt->pkt.signature;

            if (IS_KEY_REV (sig) &&
                (sig->keyid[0] != kid[0] || sig->keyid[1] != kid[1]))
              {
                int rc = check_revocation_keys (pk, sig);
                if (rc == 0)
                  {
                    *r_revoked = 2;
                    sig_to_revoke_info (sig, rinfo);
                    /* Don't continue checking since we can't be any
                       more revoked than this.  */
                    break;
                  }
                else if (gpg_err_code (rc) == GPG_ERR_NO_PUBKEY)
                  pk->flags.maybe_revoked = 1;

                /* A failure here means the sig did not verify, was
                   not issued by a revocation key, or a revocation
                   key loop was broken.  If a revocation key isn't
                   findable, however, the key might be revoked and
                   we don't know it.  */

                /* TODO: In the future handle subkey and cert
                   revocations?  PGP doesn't, but it's in 2440. */
              }
          }
      }

  /* Second pass: Look at the self-signature of all user IDs.  */
  signode = uidnode = NULL;
  sigdate = 0; /* Helper variable to find the latest signature in one UID. */
  for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY; k = k->next)
    {
      if (k->pkt->pkttype == PKT_USER_ID)
        {
          if (uidnode && signode)
            {
              fixup_uidnode (uidnode, signode, keytimestamp);
              pk->flags.valid = 1;
            }
          uidnode = k;
          signode = NULL;
          sigdate = 0;
        }
      else if (k->pkt->pkttype == PKT_SIGNATURE && uidnode)
        {
          PKT_signature *sig = k->pkt->pkt.signature;
          if (sig->keyid[0] == kid[0] && sig->keyid[1] == kid[1])
            {
              if (check_key_signature (keyblock, k, NULL))
                ;               /* signature did not verify */
              else if ((IS_UID_SIG (sig) || IS_UID_REV (sig))
                       && sig->timestamp >= sigdate)
                {
                  /* Note: we allow to invalidate cert revocations
                   * by a newer signature.  An attacker can't use this
                   * because a key should be revoced with a key revocation.
                   * The reason why we have to allow for that is that at
                   * one time an email address may become invalid but later
                   * the same email address may become valid again (hired,
                   * fired, hired again).  */

                  sigdate = sig->timestamp;
                  signode = k;
                  signode->pkt->pkt.signature->flags.chosen_selfsig = 0;
                  if (sig->version > sigversion)
                    sigversion = sig->version;
                }
            }
        }
    }
  if (uidnode && signode)
    {
      fixup_uidnode (uidnode, signode, keytimestamp);
      pk->flags.valid = 1;
    }

  /* If the key isn't valid yet, and we have
     --allow-non-selfsigned-uid set, then force it valid. */
  if (!pk->flags.valid && opt.allow_non_selfsigned_uid)
    {
      if (opt.verbose)
        log_info (_("Invalid key %s made valid by"
                    " --allow-non-selfsigned-uid\n"), keystr_from_pk (pk));
      pk->flags.valid = 1;
    }

  /* The key STILL isn't valid, so try and find an ultimately
     trusted signature. */
  if (!pk->flags.valid)
    {
      uidnode = NULL;

      for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY;
           k = k->next)
        {
          if (k->pkt->pkttype == PKT_USER_ID)
            uidnode = k;
          else if (k->pkt->pkttype == PKT_SIGNATURE && uidnode)
            {
              PKT_signature *sig = k->pkt->pkt.signature;

              if (sig->keyid[0] != kid[0] || sig->keyid[1] != kid[1])
                {
                  PKT_public_key *ultimate_pk;

                  ultimate_pk = xmalloc_clear (sizeof (*ultimate_pk));

                  /* We don't want to use the full get_pubkey to
                     avoid infinite recursion in certain cases.
                     There is no reason to check that an ultimately
                     trusted key is still valid - if it has been
                     revoked or the user should also renmove the
                     ultimate trust flag.  */
                  if (get_pubkey_fast (ultimate_pk, sig->keyid) == 0
                      && check_key_signature2 (keyblock, k, ultimate_pk,
                                               NULL, NULL, NULL, NULL) == 0
                      && get_ownertrust (ultimate_pk) == TRUST_ULTIMATE)
                    {
                      free_public_key (ultimate_pk);
                      pk->flags.valid = 1;
                      break;
                    }

                  free_public_key (ultimate_pk);
                }
            }
        }
    }

  /* Record the highest selfsig version so we know if this is a v3
     key through and through, or a v3 key with a v4 selfsig
     somewhere.  This is useful in a few places to know if the key
     must be treated as PGP2-style or OpenPGP-style.  Note that a
     selfsig revocation with a higher version number will also raise
     this value.  This is okay since such a revocation must be
     issued by the user (i.e. it cannot be issued by someone else to
     modify the key behavior.) */

  pk->selfsigversion = sigversion;

  /* Now that we had a look at all user IDs we can now get some information
   * from those user IDs.
   */

  if (!key_usage)
    {
      /* Find the latest user ID with key flags set. */
      uiddate = 0; /* Helper to find the latest user ID.  */
      for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY;
           k = k->next)
        {
          if (k->pkt->pkttype == PKT_USER_ID)
            {
              PKT_user_id *uid = k->pkt->pkt.user_id;
              if (uid->help_key_usage && uid->created > uiddate)
                {
                  key_usage = uid->help_key_usage;
                  uiddate = uid->created;
                }
            }
        }
    }
  if (!key_usage)
    {
      /* No key flags at all: get it from the algo.  */
      key_usage = openpgp_pk_algo_usage (pk->pubkey_algo);
    }
  else
    {
      /* Check that the usage matches the usage as given by the algo.  */
      int x = openpgp_pk_algo_usage (pk->pubkey_algo);
      if (x) /* Mask it down to the actual allowed usage.  */
        key_usage &= x;
    }

  /* Whatever happens, it's a primary key, so it can certify. */
  pk->pubkey_usage = key_usage | PUBKEY_USAGE_CERT;

  if (!key_expire_seen)
    {
      /* Find the latest valid user ID with a key expiration set
       * Note, that this may be a different one from the above because
       * some user IDs may have no expiration date set.  */
      uiddate = 0;
      for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY;
           k = k->next)
        {
          if (k->pkt->pkttype == PKT_USER_ID)
            {
              PKT_user_id *uid = k->pkt->pkt.user_id;
              if (uid->help_key_expire && uid->created > uiddate)
                {
                  key_expire = uid->help_key_expire;
                  uiddate = uid->created;
                }
            }
        }
    }

  /* Currently only v3 keys have a maximum expiration date, but I'll
     bet v5 keys get this feature again. */
  if (key_expire == 0
      || (pk->max_expiredate && key_expire > pk->max_expiredate))
    key_expire = pk->max_expiredate;

  pk->has_expired = key_expire >= curtime ? 0 : key_expire;
  pk->expiredate = key_expire;

  /* Fixme: we should see how to get rid of the expiretime fields  but
   * this needs changes at other places too. */

  /* And now find the real primary user ID and delete all others.  */
  uiddate = uiddate2 = 0;
  uidnode = uidnode2 = NULL;
  for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY; k = k->next)
    {
      if (k->pkt->pkttype == PKT_USER_ID && !k->pkt->pkt.user_id->attrib_data)
        {
          PKT_user_id *uid = k->pkt->pkt.user_id;
          if (uid->is_primary)
            {
              if (uid->created > uiddate)
                {
                  uiddate = uid->created;
                  uidnode = k;
                }
              else if (uid->created == uiddate && uidnode)
                {
                  /* The dates are equal, so we need to do a
                     different (and arbitrary) comparison.  This
                     should rarely, if ever, happen.  It's good to
                     try and guarantee that two different GnuPG
                     users with two different keyrings at least pick
                     the same primary. */
                  if (cmp_user_ids (uid, uidnode->pkt->pkt.user_id) > 0)
                    uidnode = k;
                }
            }
          else
            {
              if (uid->created > uiddate2)
                {
                  uiddate2 = uid->created;
                  uidnode2 = k;
                }
              else if (uid->created == uiddate2 && uidnode2)
                {
                  if (cmp_user_ids (uid, uidnode2->pkt->pkt.user_id) > 0)
                    uidnode2 = k;
                }
            }
        }
    }
  if (uidnode)
    {
      for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY;
           k = k->next)
        {
          if (k->pkt->pkttype == PKT_USER_ID &&
              !k->pkt->pkt.user_id->attrib_data)
            {
              PKT_user_id *uid = k->pkt->pkt.user_id;
              if (k != uidnode)
                uid->is_primary = 0;
            }
        }
    }
  else if (uidnode2)
    {
      /* None is flagged primary - use the latest user ID we have,
         and disambiguate with the arbitrary packet comparison. */
      uidnode2->pkt->pkt.user_id->is_primary = 1;
    }
  else
    {
      /* None of our uids were self-signed, so pick the one that
         sorts first to be the primary.  This is the best we can do
         here since there are no self sigs to date the uids. */

      uidnode = NULL;

      for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY;
           k = k->next)
        {
          if (k->pkt->pkttype == PKT_USER_ID
              && !k->pkt->pkt.user_id->attrib_data)
            {
              if (!uidnode)
                {
                  uidnode = k;
                  uidnode->pkt->pkt.user_id->is_primary = 1;
                  continue;
                }
              else
                {
                  if (cmp_user_ids (k->pkt->pkt.user_id,
                                    uidnode->pkt->pkt.user_id) > 0)
                    {
                      uidnode->pkt->pkt.user_id->is_primary = 0;
                      uidnode = k;
                      uidnode->pkt->pkt.user_id->is_primary = 1;
                    }
                  else
                    k->pkt->pkt.user_id->is_primary = 0;        /* just to be
                                                                   safe */
                }
            }
        }
    }
}

/* Convert a buffer to a signature.  Useful for 0x19 embedded sigs.
   Caller must free the signature when they are done. */
static PKT_signature *
buf_to_sig (const byte * buf, size_t len)
{
  PKT_signature *sig = xmalloc_clear (sizeof (PKT_signature));
  IOBUF iobuf = iobuf_temp_with_content (buf, len);
  int save_mode = set_packet_list_mode (0);

  if (parse_signature (iobuf, PKT_SIGNATURE, len, sig) != 0)
    {
      xfree (sig);
      sig = NULL;
    }

  set_packet_list_mode (save_mode);
  iobuf_close (iobuf);

  return sig;
}

static void
merge_selfsigs_subkey (KBNODE keyblock, KBNODE subnode)
{
  PKT_public_key *mainpk = NULL, *subpk = NULL;
  PKT_signature *sig;
  KBNODE k;
  u32 mainkid[2];
  u32 sigdate = 0;
  KBNODE signode;
  u32 curtime = make_timestamp ();
  unsigned int key_usage = 0;
  u32 keytimestamp = 0;
  u32 key_expire = 0;
  const byte *p;

  if (subnode->pkt->pkttype != PKT_PUBLIC_SUBKEY)
    BUG ();
  mainpk = keyblock->pkt->pkt.public_key;
  if (mainpk->version < 4)
    return;/* (actually this should never happen) */
  keyid_from_pk (mainpk, mainkid);
  subpk = subnode->pkt->pkt.public_key;
  keytimestamp = subpk->timestamp;

  subpk->flags.valid = 0;
  subpk->main_keyid[0] = mainpk->main_keyid[0];
  subpk->main_keyid[1] = mainpk->main_keyid[1];

  /* Find the latest key binding self-signature.  */
  signode = NULL;
  sigdate = 0; /* Helper to find the latest signature.  */
  for (k = subnode->next; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY;
       k = k->next)
    {
      if (k->pkt->pkttype == PKT_SIGNATURE)
        {
          sig = k->pkt->pkt.signature;
          if (sig->keyid[0] == mainkid[0] && sig->keyid[1] == mainkid[1])
            {
              if (check_key_signature (keyblock, k, NULL))
                ; /* Signature did not verify.  */
              else if (IS_SUBKEY_REV (sig))
                {
                  /* Note that this means that the date on a
                     revocation sig does not matter - even if the
                     binding sig is dated after the revocation sig,
                     the subkey is still marked as revoked.  This
                     seems ok, as it is just as easy to make new
                     subkeys rather than re-sign old ones as the
                     problem is in the distribution.  Plus, PGP (7)
                     does this the same way.  */
                  subpk->flags.revoked = 1;
                  sig_to_revoke_info (sig, &subpk->revoked);
                  /* Although we could stop now, we continue to
                   * figure out other information like the old expiration
                   * time.  */
                }
              else if (IS_SUBKEY_SIG (sig) && sig->timestamp >= sigdate)
                {
                  if (sig->flags.expired)
                    ; /* Signature has expired - ignore it.  */
                  else
                    {
                      sigdate = sig->timestamp;
                      signode = k;
                      signode->pkt->pkt.signature->flags.chosen_selfsig = 0;
                    }
                }
            }
        }
    }

  /* No valid key binding.  */
  if (!signode)
    return;

  sig = signode->pkt->pkt.signature;
  sig->flags.chosen_selfsig = 1; /* So we know which selfsig we chose later.  */

  key_usage = parse_key_usage (sig);
  if (!key_usage)
    {
      /* No key flags at all: get it from the algo.  */
      key_usage = openpgp_pk_algo_usage (subpk->pubkey_algo);
    }
  else
    {
      /* Check that the usage matches the usage as given by the algo.  */
      int x = openpgp_pk_algo_usage (subpk->pubkey_algo);
      if (x) /* Mask it down to the actual allowed usage.  */
        key_usage &= x;
    }

  subpk->pubkey_usage = key_usage;

  p = parse_sig_subpkt (sig->hashed, SIGSUBPKT_KEY_EXPIRE, NULL);
  if (p && buf32_to_u32 (p))
    key_expire = keytimestamp + buf32_to_u32 (p);
  else
    key_expire = 0;
  subpk->has_expired = key_expire >= curtime ? 0 : key_expire;
  subpk->expiredate = key_expire;

  /* Algo doesn't exist.  */
  if (openpgp_pk_test_algo (subpk->pubkey_algo))
    return;

  subpk->flags.valid = 1;

  /* Find the most recent 0x19 embedded signature on our self-sig. */
  if (!subpk->flags.backsig)
    {
      int seq = 0;
      size_t n;
      PKT_signature *backsig = NULL;

      sigdate = 0;

      /* We do this while() since there may be other embedded
         signatures in the future.  We only want 0x19 here. */

      while ((p = enum_sig_subpkt (sig->hashed,
                                   SIGSUBPKT_SIGNATURE, &n, &seq, NULL)))
        if (n > 3
            && ((p[0] == 3 && p[2] == 0x19) || (p[0] == 4 && p[1] == 0x19)))
          {
            PKT_signature *tempsig = buf_to_sig (p, n);
            if (tempsig)
              {
                if (tempsig->timestamp > sigdate)
                  {
                    if (backsig)
                      free_seckey_enc (backsig);

                    backsig = tempsig;
                    sigdate = backsig->timestamp;
                  }
                else
                  free_seckey_enc (tempsig);
              }
          }

      seq = 0;

      /* It is safe to have this in the unhashed area since the 0x19
         is located on the selfsig for convenience, not security. */

      while ((p = enum_sig_subpkt (sig->unhashed, SIGSUBPKT_SIGNATURE,
                                   &n, &seq, NULL)))
        if (n > 3
            && ((p[0] == 3 && p[2] == 0x19) || (p[0] == 4 && p[1] == 0x19)))
          {
            PKT_signature *tempsig = buf_to_sig (p, n);
            if (tempsig)
              {
                if (tempsig->timestamp > sigdate)
                  {
                    if (backsig)
                      free_seckey_enc (backsig);

                    backsig = tempsig;
                    sigdate = backsig->timestamp;
                  }
                else
                  free_seckey_enc (tempsig);
              }
          }

      if (backsig)
        {
          /* At ths point, backsig contains the most recent 0x19 sig.
             Let's see if it is good. */

          /* 2==valid, 1==invalid, 0==didn't check */
          if (check_backsig (mainpk, subpk, backsig) == 0)
            subpk->flags.backsig = 2;
          else
            subpk->flags.backsig = 1;

          free_seckey_enc (backsig);
        }
    }
}


/*
 * Merge information from the self-signatures with the key, so that
 * we can later use them more easy.
 * The function works by first applying the self signatures to the
 * primary key and the to each subkey.
 * Here are the rules we use to decide which inormation from which
 * self-signature is used:
 * We check all self signatures or validity and ignore all invalid signatures.
 * All signatures are then ordered by their creation date ....
 * For the primary key:
 *   FIXME the docs
 */
static void
merge_selfsigs (KBNODE keyblock)
{
  KBNODE k;
  int revoked;
  struct revoke_info rinfo;
  PKT_public_key *main_pk;
  prefitem_t *prefs;
  unsigned int mdc_feature;

  if (keyblock->pkt->pkttype != PKT_PUBLIC_KEY)
    {
      if (keyblock->pkt->pkttype == PKT_SECRET_KEY)
        {
          log_error ("expected public key but found secret key "
                     "- must stop\n");
          /* We better exit here because a public key is expected at
             other places too.  FIXME: Figure this out earlier and
             don't get to here at all */
          g10_exit (1);
        }
      BUG ();
    }

  merge_selfsigs_main (keyblock, &revoked, &rinfo);

  /* Now merge in the data from each of the subkeys.  */
  for (k = keyblock; k; k = k->next)
    {
      if (k->pkt->pkttype == PKT_PUBLIC_SUBKEY)
        {
          merge_selfsigs_subkey (keyblock, k);
        }
    }

  main_pk = keyblock->pkt->pkt.public_key;
  if (revoked || main_pk->has_expired || !main_pk->flags.valid)
    {
      /* If the primary key is revoked, expired, or invalid we
       * better set the appropriate flags on that key and all
       * subkeys.  */
      for (k = keyblock; k; k = k->next)
        {
          if (k->pkt->pkttype == PKT_PUBLIC_KEY
              || k->pkt->pkttype == PKT_PUBLIC_SUBKEY)
            {
              PKT_public_key *pk = k->pkt->pkt.public_key;
              if (!main_pk->flags.valid)
                pk->flags.valid = 0;
              if (revoked && !pk->flags.revoked)
                {
                  pk->flags.revoked = revoked;
                  memcpy (&pk->revoked, &rinfo, sizeof (rinfo));
                }
              if (main_pk->has_expired)
                pk->has_expired = main_pk->has_expired;
            }
        }
      return;
    }

  /* Set the preference list of all keys to those of the primary real
   * user ID.  Note: we use these preferences when we don't know by
   * which user ID the key has been selected.
   * fixme: we should keep atoms of commonly used preferences or
   * use reference counting to optimize the preference lists storage.
   * FIXME: it might be better to use the intersection of
   * all preferences.
   * Do a similar thing for the MDC feature flag.  */
  prefs = NULL;
  mdc_feature = 0;
  for (k = keyblock; k && k->pkt->pkttype != PKT_PUBLIC_SUBKEY; k = k->next)
    {
      if (k->pkt->pkttype == PKT_USER_ID
          && !k->pkt->pkt.user_id->attrib_data
          && k->pkt->pkt.user_id->is_primary)
        {
          prefs = k->pkt->pkt.user_id->prefs;
          mdc_feature = k->pkt->pkt.user_id->flags.mdc;
          break;
        }
    }
  for (k = keyblock; k; k = k->next)
    {
      if (k->pkt->pkttype == PKT_PUBLIC_KEY
          || k->pkt->pkttype == PKT_PUBLIC_SUBKEY)
        {
          PKT_public_key *pk = k->pkt->pkt.public_key;
          if (pk->prefs)
            xfree (pk->prefs);
          pk->prefs = copy_prefs (prefs);
          pk->flags.mdc = mdc_feature;
        }
    }
}


\f
/* See whether the key fits our requirements and in case we do not
 * request the primary key, select a suitable subkey.
 *
 * Returns: True when a suitable key has been found.
 *
 * We have to distinguish four cases:  FIXME!
 *  1. No usage and no primary key requested
 *     Examples for this case are that we have a keyID to be used
 *     for decrytion or verification.
 *  2. No usage but primary key requested
 *     This is the case for all functions which work on an
 *     entire keyblock, e.g. for editing or listing
 *  3. Usage and primary key requested
 *     FXME
 *  4. Usage but no primary key requested
 *     FIXME
 * FIXME: Tell what is going to happen here and something about the rationale
 * Note: We don't use this function if no specific usage is requested;
 *       This way the getkey functions can be used for plain key listings.
 *
 * CTX ist the keyblock we are investigating, if FOUNDK is not NULL this
 * is the key we actually found by looking at the keyid or a fingerprint and
 * may either point to the primary or one of the subkeys.  */
static int
finish_lookup (GETKEY_CTX ctx)
{
  KBNODE keyblock = ctx->keyblock;
  KBNODE k;
  KBNODE foundk = NULL;
  PKT_user_id *foundu = NULL;
#define USAGE_MASK  (PUBKEY_USAGE_SIG|PUBKEY_USAGE_ENC|PUBKEY_USAGE_CERT)
  unsigned int req_usage = (ctx->req_usage & USAGE_MASK);
  /* Request the primary if we're certifying another key, and also
     if signing data while --pgp6 or --pgp7 is on since pgp 6 and 7
     do not understand signatures made by a signing subkey.  PGP 8
     does. */
  int req_prim = (ctx->req_usage & PUBKEY_USAGE_CERT) ||
    ((PGP6 || PGP7) && (ctx->req_usage & PUBKEY_USAGE_SIG));
  u32 latest_date;
  KBNODE latest_key;
  u32 curtime = make_timestamp ();

  assert (keyblock->pkt->pkttype == PKT_PUBLIC_KEY);

  ctx->found_key = NULL;

  if (ctx->exact)
    {
      for (k = keyblock; k; k = k->next)
        {
          if ((k->flag & 1))
            {
              assert (k->pkt->pkttype == PKT_PUBLIC_KEY
                      || k->pkt->pkttype == PKT_PUBLIC_SUBKEY);
              foundk = k;
              break;
            }
        }
    }

  for (k = keyblock; k; k = k->next)
    {
      if ((k->flag & 2))
        {
          assert (k->pkt->pkttype == PKT_USER_ID);
          foundu = k->pkt->pkt.user_id;
          break;
        }
    }

  if (DBG_LOOKUP)
    log_debug ("finish_lookup: checking key %08lX (%s)(req_usage=%x)\n",
               (ulong) keyid_from_pk (keyblock->pkt->pkt.public_key, NULL),
               foundk ? "one" : "all", req_usage);

  if (!req_usage)
    {
      latest_key = foundk ? foundk : keyblock;
      goto found;
    }

  latest_date = 0;
  latest_key = NULL;
  /* Do not look at subkeys if a certification key is requested.  */
  if ((!foundk || foundk->pkt->pkttype == PKT_PUBLIC_SUBKEY) && !req_prim)
    {
      KBNODE nextk;
      /* Either start a loop or check just this one subkey.  */
      for (k = foundk ? foundk : keyblock; k; k = nextk)
        {
          PKT_public_key *pk;
          nextk = k->next;
          if (k->pkt->pkttype != PKT_PUBLIC_SUBKEY)
            continue;
          if (foundk)
            nextk = NULL; /* what a hack */
          pk = k->pkt->pkt.public_key;
          if (DBG_LOOKUP)
            log_debug ("\tchecking subkey %08lX\n",
                       (ulong) keyid_from_pk (pk, NULL));
          if (!pk->flags.valid)
            {
              if (DBG_LOOKUP)
                log_debug ("\tsubkey not valid\n");
              continue;
            }
          if (pk->flags.revoked)
            {
              if (DBG_LOOKUP)
                log_debug ("\tsubkey has been revoked\n");
              continue;
            }
          if (pk->has_expired)
            {
              if (DBG_LOOKUP)
                log_debug ("\tsubkey has expired\n");
              continue;
            }
          if (pk->timestamp > curtime && !opt.ignore_valid_from)
            {
              if (DBG_LOOKUP)
                log_debug ("\tsubkey not yet valid\n");
              continue;
            }

          if (!((pk->pubkey_usage & USAGE_MASK) & req_usage))
            {
              if (DBG_LOOKUP)
                log_debug ("\tusage does not match: want=%x have=%x\n",
                           req_usage, pk->pubkey_usage);
              continue;
            }

          if (DBG_LOOKUP)
            log_debug ("\tsubkey might be fine\n");
          /* In case a key has a timestamp of 0 set, we make sure
             that it is used.  A better change would be to compare
             ">=" but that might also change the selected keys and
             is as such a more intrusive change.  */
          if (pk->timestamp > latest_date || (!pk->timestamp && !latest_date))
            {
              latest_date = pk->timestamp;
              latest_key = k;
            }
        }
    }

  /* Okay now try the primary key unless we want an exact
   * key ID match on a subkey */
  if ((!latest_key && !(ctx->exact && foundk != keyblock)) || req_prim)
    {
      PKT_public_key *pk;
      if (DBG_LOOKUP && !foundk && !req_prim)
        log_debug ("\tno suitable subkeys found - trying primary\n");
      pk = keyblock->pkt->pkt.public_key;
      if (!pk->flags.valid)
        {
          if (DBG_LOOKUP)
            log_debug ("\tprimary key not valid\n");
        }
      else if (pk->flags.revoked)
        {
          if (DBG_LOOKUP)
            log_debug ("\tprimary key has been revoked\n");
        }
      else if (pk->has_expired)
        {
          if (DBG_LOOKUP)
            log_debug ("\tprimary key has expired\n");
        }
      else if (!((pk->pubkey_usage & USAGE_MASK) & req_usage))
        {
          if (DBG_LOOKUP)
            log_debug ("\tprimary key usage does not match: "
                       "want=%x have=%x\n", req_usage, pk->pubkey_usage);
        }
      else /* Okay.  */
        {
          if (DBG_LOOKUP)
            log_debug ("\tprimary key may be used\n");
          latest_key = keyblock;
          latest_date = pk->timestamp;
        }
    }

  if (!latest_key)
    {
      if (DBG_LOOKUP)
        log_debug ("\tno suitable key found -  giving up\n");
      return 0; /* Not found.  */
    }

found:
  if (DBG_LOOKUP)
    log_debug ("\tusing key %08lX\n",
               (ulong) keyid_from_pk (latest_key->pkt->pkt.public_key, NULL));

  if (latest_key)
    {
      PKT_public_key *pk = latest_key->pkt->pkt.public_key;
      if (pk->user_id)
        free_user_id (pk->user_id);
      pk->user_id = scopy_user_id (foundu);
    }

  ctx->found_key = latest_key;

  if (latest_key != keyblock && opt.verbose)
    {
      char *tempkeystr =
        xstrdup (keystr_from_pk (latest_key->pkt->pkt.public_key));
      log_info (_("using subkey %s instead of primary key %s\n"),
                tempkeystr, keystr_from_pk (keyblock->pkt->pkt.public_key));
      xfree (tempkeystr);
    }

  cache_user_id (keyblock);

  return 1; /* Found.  */
}


/* Return true if all the search modes are fingerprints.  */
static int
search_modes_are_fingerprint (getkey_ctx_t ctx)
{
  size_t n, found;

  for (n=found=0; n < ctx->nitems; n++)
    {
      switch (ctx->items[n].mode)
        {
        case KEYDB_SEARCH_MODE_FPR16:
        case KEYDB_SEARCH_MODE_FPR20:
        case KEYDB_SEARCH_MODE_FPR:
          found++;
          break;
        default:
          break;
        }
    }
  return found && found == ctx->nitems;
}


/* The main function to lookup a key.  On success the found keyblock
   is stored at RET_KEYBLOCK and also in CTX.  If WANT_SECRET is true
   a corresponding secret key is required.  */
static int
lookup (getkey_ctx_t ctx, kbnode_t *ret_keyblock, int want_secret)
{
  int rc;
  int no_suitable_key = 0;

  for (;;)
    {
      rc = keydb_search (ctx->kr_handle, ctx->items, ctx->nitems, NULL);
      /* Skip over all legacy keys but only if they are not requested
         by fingerprints.
         Fixme: The lower level keydb code should actually do that but
         then it would be harder to report the number of skipped
         legacy keys during import. */
      if (gpg_err_code (rc) == GPG_ERR_LEGACY_KEY
          && !(ctx->nitems && ctx->items->mode == KEYDB_SEARCH_MODE_FIRST)
          && !search_modes_are_fingerprint (ctx))
        continue;
      if (rc)
        break;

      /* If we are searching for the first key we have to make sure
         that the next iteration does not do an implicit reset.
         This can be triggered by an empty key ring. */
      if (ctx->nitems && ctx->items->mode == KEYDB_SEARCH_MODE_FIRST)
        ctx->items->mode = KEYDB_SEARCH_MODE_NEXT;

      rc = keydb_get_keyblock (ctx->kr_handle, &ctx->keyblock);
      if (rc)
        {
          log_error ("keydb_get_keyblock failed: %s\n", gpg_strerror (rc));
          rc = 0;
          goto skip;
        }

      if (want_secret && agent_probe_any_secret_key (NULL, ctx->keyblock))
        goto skip; /* No secret key available.  */

      /* Warning: node flag bits 0 and 1 should be preserved by
       * merge_selfsigs.  For secret keys, premerge transferred the
       * keys to the keyblock.  */
      merge_selfsigs (ctx->keyblock);
      if (finish_lookup (ctx))
        {
          no_suitable_key = 0;
          goto found;
        }
      else
        no_suitable_key = 1;

    skip:
      /* Release resources and continue search. */
      release_kbnode (ctx->keyblock);
      ctx->keyblock = NULL;
      /* We need to disable the caching so that for an exact key
         search we won't get the result back from the cache and thus
         end up in an endless loop.  Disabling the cache here at this
         point is sufficient because even a cached result won't be
         used after a call to keydb_disable_caching.  */
      keydb_disable_caching (ctx->kr_handle);
    }

found:
  if (rc && gpg_err_code (rc) != GPG_ERR_NOT_FOUND
      && gpg_err_code (rc) != GPG_ERR_LEGACY_KEY)
    log_error ("keydb_search failed: %s\n", gpg_strerror (rc));

  if (!rc)
    {
      *ret_keyblock = ctx->keyblock; /* Return the keyblock.  */
      ctx->keyblock = NULL;
    }
  else if ((gpg_err_code (rc) == GPG_ERR_NOT_FOUND
            || gpg_err_code (rc) == GPG_ERR_LEGACY_KEY) && no_suitable_key)
    rc = want_secret? GPG_ERR_UNUSABLE_SECKEY : GPG_ERR_UNUSABLE_PUBKEY;
  else if (gpg_err_code (rc) == GPG_ERR_NOT_FOUND)
    rc = want_secret? GPG_ERR_NO_SECKEY : GPG_ERR_NO_PUBKEY;

  release_kbnode (ctx->keyblock);
  ctx->keyblock = NULL;

  return rc;
}




/*
 * Enumerate certain secret keys.  Caller must use these procedure:
 *  1) create a void pointer and initialize it to NULL
 *  2) pass this void pointer by reference to this function
 *     and provide space for the secret key (pass a buffer for sk)
 *  3) call this function as long as it does not return an error.
 *     The error code GPG_ERR_EOF indicates the end of the listing.
 *  4) Always call this function a last time with SK set to NULL,
 *     so that can free it's context.
 */
gpg_error_t
enum_secret_keys (void **context, PKT_public_key *sk)
{
  gpg_error_t err = 0;
  const char *name;
  struct
  {
    int eof;
    int state;
    strlist_t sl;
    kbnode_t keyblock;
    kbnode_t node;
  } *c = *context;

  if (!c)
    {
      /* Make a new context.  */
      c = xtrycalloc (1, sizeof *c);
      if (!c)
        return gpg_error_from_syserror ();
      *context = c;
    }

  if (!sk)
    {
      /* Free the context.  */
      release_kbnode (c->keyblock);
      xfree (c);
      *context = NULL;
      return 0;
    }

  if (c->eof)
    return gpg_error (GPG_ERR_EOF);

  for (;;)
    {
      /* Loop until we have a keyblock.  */
      while (!c->keyblock)
        {
          /* Loop over the list of secret keys.  */
          do
            {
              name = NULL;
              switch (c->state)
                {
                case 0: /* First try to use the --default-key.  */
                  if (opt.def_secret_key && *opt.def_secret_key)
                    name = opt.def_secret_key;
                  c->state = 1;
                  break;

                case 1: /* Init list of keys to try.  */
                  c->sl = opt.secret_keys_to_try;
                  c->state++;
                  break;

                case 2: /* Get next item from list.  */
                  if (c->sl)
                    {
                      name = c->sl->d;
                      c->sl = c->sl->next;
                    }
                  else
                    c->state++;
                  break;

                default: /* No more names to check - stop.  */
                  c->eof = 1;
                  return gpg_error (GPG_ERR_EOF);
                }
            }
          while (!name || !*name);

          err = getkey_byname (NULL, NULL, name, 1, &c->keyblock);
          if (err)
            {
              /* getkey_byname might return a keyblock even in the
                 error case - I have not checked.  Thus better release
                 it.  */
              release_kbnode (c->keyblock);
              c->keyblock = NULL;
            }
          else
            c->node = c->keyblock;
        }

      /* Get the next key from the current keyblock.  */
      for (; c->node; c->node = c->node->next)
        {
          if (c->node->pkt->pkttype == PKT_PUBLIC_KEY
              || c->node->pkt->pkttype == PKT_PUBLIC_SUBKEY)
            {
              copy_public_key (sk, c->node->pkt->pkt.public_key);
              c->node = c->node->next;
              return 0; /* Found.  */
            }
        }

      /* Dispose the keyblock and continue.  */
      release_kbnode (c->keyblock);
      c->keyblock = NULL;
    }
}

\f
/*********************************************
 ***********  User ID printing helpers *******
 *********************************************/

/* Return a string with a printable representation of the user_id.
 * this string must be freed by xfree.   */
static char *
get_user_id_string (u32 * keyid, int mode, size_t *r_len)
{
  user_id_db_t r;
  keyid_list_t a;
  int pass = 0;
  char *p;

  /* Try it two times; second pass reads from key resources.  */
  do
    {
      for (r = user_id_db; r; r = r->next)
        {
          for (a = r->keyids; a; a = a->next)
            {
              if (a->keyid[0] == keyid[0] && a->keyid[1] == keyid[1])
                {
                  if (mode == 2)
                    {
                      /* An empty string as user id is possible.  Make
                         sure that the malloc allocates one byte and
                         does not bail out.  */
                      p = xmalloc (r->len? r->len : 1);
                      memcpy (p, r->name, r->len);
                      if (r_len)
                        *r_len = r->len;
                    }
                  else
                    {
                      if (mode)
                        p = xasprintf ("%08lX%08lX %.*s",
                                       (ulong) keyid[0], (ulong) keyid[1],
                                       r->len, r->name);
                      else
                        p = xasprintf ("%s %.*s", keystr (keyid),
                                       r->len, r->name);
                      if (r_len)
                        *r_len = strlen (p);
                    }

                  return p;
                }
            }
        }
    }
  while (++pass < 2 && !get_pubkey (NULL, keyid));

  if (mode == 2)
    p = xstrdup (user_id_not_found_utf8 ());
  else if (mode)
    p = xasprintf ("%08lX%08lX [?]", (ulong) keyid[0], (ulong) keyid[1]);
  else
    p = xasprintf ("%s [?]", keystr (keyid));

  if (r_len)
    *r_len = strlen (p);
  return p;
}


char *
get_user_id_string_native (u32 * keyid)
{
  char *p = get_user_id_string (keyid, 0, NULL);
  char *p2 = utf8_to_native (p, strlen (p), 0);
  xfree (p);
  return p2;
}


char *
get_long_user_id_string (u32 * keyid)
{
  return get_user_id_string (keyid, 1, NULL);
}


/* Please try to use get_user_byfpr instead of this one.  */
char *
get_user_id (u32 * keyid, size_t * rn)
{
  return get_user_id_string (keyid, 2, rn);
}


/* Please try to use get_user_id_byfpr_native instead of this one.  */
char *
get_user_id_native (u32 * keyid)
{
  size_t rn;
  char *p = get_user_id (keyid, &rn);
  char *p2 = utf8_to_native (p, rn, 0);
  xfree (p);
  return p2;
}


/* Return a user id from the caching by looking it up using the FPR
   which must be of size MAX_FINGERPRINT_LEN.  */
char *
get_user_id_byfpr (const byte *fpr, size_t *rn)
{
  user_id_db_t r;
  char *p;
  int pass = 0;

  /* Try it two times; second pass reads from key resources.  */
  do
    {
      for (r = user_id_db; r; r = r->next)
        {
          keyid_list_t a;
          for (a = r->keyids; a; a = a->next)
            {
              if (!memcmp (a->fpr, fpr, MAX_FINGERPRINT_LEN))
                {
                  /* An empty string as user id is possible.  Make
                     sure that the malloc allocates one byte and does
                     not bail out.  */
                  p = xmalloc (r->len? r->len : 1);
                  memcpy (p, r->name, r->len);
                  *rn = r->len;
                  return p;
                }
            }
        }
    }
  while (++pass < 2 && !get_pubkey_byfpr (NULL, fpr));
  p = xstrdup (user_id_not_found_utf8 ());
  *rn = strlen (p);
  return p;
}

char *
get_user_id_byfpr_native (const byte *fpr)
{
  size_t rn;
  char *p = get_user_id_byfpr (fpr, &rn);
  char *p2 = utf8_to_native (p, rn, 0);
  xfree (p);
  return p2;
}



KEYDB_HANDLE
get_ctx_handle (GETKEY_CTX ctx)
{
  return ctx->kr_handle;
}

static void
free_akl (struct akl *akl)
{
  if (! akl)
    return;

  if (akl->spec)
    free_keyserver_spec (akl->spec);

  xfree (akl);
}

void
release_akl (void)
{
  while (opt.auto_key_locate)
    {
      struct akl *akl2 = opt.auto_key_locate;
      opt.auto_key_locate = opt.auto_key_locate->next;
      free_akl (akl2);
    }
}

/* Returns false on error. */
int
parse_auto_key_locate (char *options)
{
  char *tok;

  while ((tok = optsep (&options)))
    {
      struct akl *akl, *check, *last = NULL;
      int dupe = 0;

      if (tok[0] == '\0')
        continue;

      akl = xmalloc_clear (sizeof (*akl));

      if (ascii_strcasecmp (tok, "clear") == 0)
        {
          xfree (akl);
          free_akl (opt.auto_key_locate);
          opt.auto_key_locate = NULL;
          continue;
        }
      else if (ascii_strcasecmp (tok, "nodefault") == 0)
        akl->type = AKL_NODEFAULT;
      else if (ascii_strcasecmp (tok, "local") == 0)
        akl->type = AKL_LOCAL;
      else if (ascii_strcasecmp (tok, "ldap") == 0)
        akl->type = AKL_LDAP;
      else if (ascii_strcasecmp (tok, "keyserver") == 0)
        akl->type = AKL_KEYSERVER;
#ifdef USE_DNS_CERT
      else if (ascii_strcasecmp (tok, "cert") == 0)
        akl->type = AKL_CERT;
#endif
      else if (ascii_strcasecmp (tok, "pka") == 0)
        akl->type = AKL_PKA;
      else if ((akl->spec = parse_keyserver_uri (tok, 1)))
        akl->type = AKL_SPEC;
      else
        {
          free_akl (akl);
          return 0;
        }

      /* We must maintain the order the user gave us */
      for (check = opt.auto_key_locate; check;
           last = check, check = check->next)
        {
          /* Check for duplicates */
          if (check->type == akl->type
              && (akl->type != AKL_SPEC
                  || (akl->type == AKL_SPEC
                      && strcmp (check->spec->uri, akl->spec->uri) == 0)))
            {
              dupe = 1;
              free_akl (akl);
              break;
            }
        }

      if (!dupe)
        {
          if (last)
            last->next = akl;
          else
            opt.auto_key_locate = akl;
        }
    }

  return 1;
}


/* Return true if a secret key or secret subkey is available for one
   of the public keys in KEYBLOCK.  */
int
have_any_secret_key (ctrl_t ctrl, kbnode_t keyblock)
{
  kbnode_t node;

  for (node = keyblock; node; node = node->next)
    if ((node->pkt->pkttype == PKT_PUBLIC_KEY
         || node->pkt->pkttype == PKT_PUBLIC_SUBKEY)
        && !agent_probe_secret_key (ctrl, node->pkt->pkt.public_key))
      return 1;
  return 0;
}


/* Return true if a secret key is available for the public key with
 * the given KEYID.  This is just a fast check and does not tell us
 * whether the secret key is valid.  It merely tells os whether there
 * is some secret key.  */
int
have_secret_key_with_kid (u32 *keyid)
{
  gpg_error_t err;
  KEYDB_HANDLE kdbhd;
  KEYDB_SEARCH_DESC desc;
  kbnode_t keyblock;
  kbnode_t node;
  int result = 0;

  kdbhd = keydb_new ();
  memset (&desc, 0, sizeof desc);
  desc.mode = KEYDB_SEARCH_MODE_LONG_KID;
  desc.u.kid[0] = keyid[0];
  desc.u.kid[1] = keyid[1];
  while (!result)
    {
      err = keydb_search (kdbhd, &desc, 1, NULL);
      if (gpg_err_code (err) == GPG_ERR_LEGACY_KEY)
        continue;
      if (err)
        break;

      err = keydb_get_keyblock (kdbhd, &keyblock);
      if (err)
        {
          log_error (_("error reading keyblock: %s\n"), gpg_strerror (err));
          break;
        }

      for (node = keyblock; node; node = node->next)
        {
          /* Bit 0 of the flags is set if the search found the key
             using that key or subkey.  */
          if ((node->flag & 1))
            {
              assert (node->pkt->pkttype == PKT_PUBLIC_KEY
                      || node->pkt->pkttype == PKT_PUBLIC_SUBKEY);

              if (!agent_probe_secret_key (NULL, node->pkt->pkt.public_key))
                {
                  result = 1;
                  break;
                }
            }
        }
      release_kbnode (keyblock);
    }

  keydb_release (kdbhd);
  return result;
}