gnupg/g10/tofu.c

/* tofu.c - TOFU trust model.
 * Copyright (C) 2015, 2016 g10 Code GmbH
 *
 * 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/>.
 */

/* TODO:

   - Format the fingerprints nicely when printing (similar to gpg
     --list-keys)
 */

#include <config.h>
#include <stdio.h>
#include <sys/stat.h>
#include <stdarg.h>
#include <sqlite3.h>

#include "gpg.h"
#include "types.h"
#include "logging.h"
#include "stringhelp.h"
#include "options.h"
#include "mbox-util.h"
#include "i18n.h"
#include "ttyio.h"
#include "trustdb.h"
#include "mkdir_p.h"
#include "gpgsql.h"
#include "status.h"
#include "sqrtu32.h"

#include "tofu.h"


#define CONTROL_L ('L' - 'A' + 1)

/* Number of signed messages required to indicate that enough history
 * is available for basic trust.  */
#define BASIC_TRUST_THRESHOLD  10
/* Number of signed messages required to indicate that a lot of
 * history is available.  */
#define FULL_TRUST_THRESHOLD  100


/* An struct with data pertaining to the tofu DB.

   To initialize this data structure, call opendbs().  Cleanup is done
   when the CTRL object is released.  To get a handle to a database,
   use the getdb() function.  This will either return an existing
   handle or open a new DB connection, as appropriate.  */
struct tofu_dbs_s
{
  sqlite3 *db;

  struct
  {
    sqlite3_stmt *savepoint_batch;
    sqlite3_stmt *savepoint_batch_commit;

    sqlite3_stmt *record_binding_get_old_policy;
    sqlite3_stmt *record_binding_update;
    sqlite3_stmt *record_binding_update2;
    sqlite3_stmt *get_policy_select_policy_and_conflict;
    sqlite3_stmt *get_trust_bindings_with_this_email;
    sqlite3_stmt *get_trust_gather_other_user_ids;
    sqlite3_stmt *get_trust_gather_signature_stats;
    sqlite3_stmt *get_trust_gather_encryption_stats;
    sqlite3_stmt *register_already_seen;
    sqlite3_stmt *register_insert;
  } s;

  int in_batch_transaction;
  int in_transaction;
  time_t batch_update_started;
};


#define STRINGIFY(s) STRINGIFY2(s)
#define STRINGIFY2(s) #s

/* The grouping parameters when collecting signature statistics.  */

/* If a message is signed a couple of hours in the future, just assume
   some clock skew.  */
#define TIME_AGO_FUTURE_IGNORE (2 * 60 * 60)
/* Days.  */
#define TIME_AGO_UNIT_SMALL (24 * 60 * 60)
#define TIME_AGO_SMALL_THRESHOLD (7 * TIME_AGO_UNIT_SMALL)
/* Months.  */
#define TIME_AGO_UNIT_MEDIUM (30 * 24 * 60 * 60)
#define TIME_AGO_MEDIUM_THRESHOLD (2 * TIME_AGO_UNIT_MEDIUM)
/* Years.  */
#define TIME_AGO_UNIT_LARGE (365 * 24 * 60 * 60)
#define TIME_AGO_LARGE_THRESHOLD (2 * TIME_AGO_UNIT_LARGE)

/* Local prototypes.  */
static gpg_error_t end_transaction (ctrl_t ctrl, int only_batch);
static char *email_from_user_id (const char *user_id);



const char *
tofu_policy_str (enum tofu_policy policy)
{
  switch (policy)
    {
    case TOFU_POLICY_NONE: return "none";
    case TOFU_POLICY_AUTO: return "auto";
    case TOFU_POLICY_GOOD: return "good";
    case TOFU_POLICY_UNKNOWN: return "unknown";
    case TOFU_POLICY_BAD: return "bad";
    case TOFU_POLICY_ASK: return "ask";
    default: return "???";
    }
}

/* Convert a binding policy (e.g., TOFU_POLICY_BAD) to a trust level
   (e.g., TRUST_BAD) in light of the current configuration.  */
int
tofu_policy_to_trust_level (enum tofu_policy policy)
{
  if (policy == TOFU_POLICY_AUTO)
    /* If POLICY is AUTO, fallback to OPT.TOFU_DEFAULT_POLICY.  */
    policy = opt.tofu_default_policy;

  switch (policy)
    {
    case TOFU_POLICY_AUTO:
      /* If POLICY and OPT.TOFU_DEFAULT_POLICY are both AUTO, default
	 to marginal trust.  */
      return TRUST_MARGINAL;
    case TOFU_POLICY_GOOD:
      return TRUST_FULLY;
    case TOFU_POLICY_UNKNOWN:
      return TRUST_UNKNOWN;
    case TOFU_POLICY_BAD:
      return TRUST_NEVER;
    case TOFU_POLICY_ASK:
      return TRUST_UNKNOWN;
    default:
      log_bug ("Bad value for trust policy: %d\n",
	       opt.tofu_default_policy);
      return 0;
    }
}



/* Start a transaction on DB.  If ONLY_BATCH is set, then this will
   start a batch transaction if we haven't started a batch transaction
   and one has been requested.  */
static gpg_error_t
begin_transaction (ctrl_t ctrl, int only_batch)
{
  tofu_dbs_t dbs = ctrl->tofu.dbs;
  int rc;
  char *err = NULL;

  log_assert (dbs);

  /* If we've been in batch update mode for a while (on average, more
   * than 500 ms), to prevent starving other gpg processes, we drop
   * and retake the batch lock.
   *
   * Note: if we wanted higher resolution, we could use
   * npth_clock_gettime.  */
  if (/* No real transactions.  */
      dbs->in_transaction == 0
      /* There is an open batch transaction.  */
      && dbs->in_batch_transaction
      /* And some time has gone by since it was started.  */
      && dbs->batch_update_started != gnupg_get_time ())
    {
      /* If we are in a batch update, then batch updates better have
         been enabled.  */
      log_assert (ctrl->tofu.batch_updated_wanted);

      end_transaction (ctrl, 2);

      /* Yield to allow another process a chance to run.  */
      gpgrt_yield ();
    }

  if (/* Batch mode is enabled.  */
      ctrl->tofu.batch_updated_wanted
      /* But we don't have an open batch transaction.  */
      && !dbs->in_batch_transaction)
    {
      /* We are in batch mode, but we don't have an open batch
       * transaction.  Since the batch save point must be the outer
       * save point, it must be taken before the inner save point.  */
      log_assert (dbs->in_transaction == 0);

      rc = gpgsql_stepx (dbs->db, &dbs->s.savepoint_batch,
                          NULL, NULL, &err,
                          "savepoint batch;", GPGSQL_ARG_END);
      if (rc)
        {
          log_error (_("error beginning transaction on TOFU database: %s\n"),
                     err);
          sqlite3_free (err);
          return gpg_error (GPG_ERR_GENERAL);
        }

      dbs->in_batch_transaction = 1;
      dbs->batch_update_started = gnupg_get_time ();
    }

  if (only_batch)
    return 0;

  log_assert(dbs->in_transaction >= 0);
  dbs->in_transaction ++;

  rc = gpgsql_exec_printf (dbs->db, NULL, NULL, &err,
                           "savepoint inner%d;",
                           dbs->in_transaction);
  if (rc)
    {
      log_error (_("error beginning transaction on TOFU database: %s\n"),
                 err);
      sqlite3_free (err);
      return gpg_error (GPG_ERR_GENERAL);
    }

  return 0;
}


/* Commit a transaction.  If ONLY_BATCH is 1, then this only ends the
 * batch transaction if we have left batch mode.  If ONLY_BATCH is 2,
 * this ends any open batch transaction even if we are still in batch
 * mode.  */
static gpg_error_t
end_transaction (ctrl_t ctrl, int only_batch)
{
  tofu_dbs_t dbs = ctrl->tofu.dbs;
  int rc;
  char *err = NULL;

  if (only_batch)
    {
      if (!dbs)
        return 0;  /* Shortcut to allow for easier cleanup code.  */

      /* If we are releasing the batch transaction, then we better not
         be in a normal transaction.  */
      log_assert (dbs->in_transaction == 0);

      if (/* Batch mode disabled?  */
          (!ctrl->tofu.batch_updated_wanted || only_batch == 2)
          /* But, we still have an open batch transaction?  */
          && dbs->in_batch_transaction)
        {
          /* The batch transaction is still in open, but we've left
           * batch mode.  */
          dbs->in_batch_transaction = 0;

          rc = gpgsql_stepx (dbs->db, &dbs->s.savepoint_batch_commit,
                             NULL, NULL, &err,
                             "release batch;", GPGSQL_ARG_END);
          if (rc)
            {
              log_error (_("error committing transaction on TOFU database: %s\n"),
                         err);
              sqlite3_free (err);
              return gpg_error (GPG_ERR_GENERAL);
            }

          return 0;
        }

      return 0;
    }

  log_assert (dbs);
  log_assert (dbs->in_transaction > 0);

  rc = gpgsql_exec_printf (dbs->db, NULL, NULL, &err,
                           "release inner%d;", dbs->in_transaction);

  dbs->in_transaction --;

  if (rc)
    {
      log_error (_("error committing transaction on TOFU database: %s\n"),
                 err);
      sqlite3_free (err);
      return gpg_error (GPG_ERR_GENERAL);
    }

  return 0;
}


static gpg_error_t
rollback_transaction (ctrl_t ctrl)
{
  tofu_dbs_t dbs = ctrl->tofu.dbs;
  int rc;
  char *err = NULL;

  log_assert (dbs);
  log_assert (dbs->in_transaction > 0);

  /* Be careful to not any progress made by closed transactions in
     batch mode.  */
  rc = gpgsql_exec_printf (dbs->db, NULL, NULL, &err,
                           "rollback to inner%d;",
                           dbs->in_transaction);

  dbs->in_transaction --;

  if (rc)
    {
      log_error (_("error rolling back transaction on TOFU database: %s\n"),
                 err);
      sqlite3_free (err);
      return gpg_error (GPG_ERR_GENERAL);
    }

  return 0;
}

void
tofu_begin_batch_update (ctrl_t ctrl)
{
  ctrl->tofu.batch_updated_wanted ++;
}

void
tofu_end_batch_update (ctrl_t ctrl)
{
  log_assert (ctrl->tofu.batch_updated_wanted > 0);
  ctrl->tofu.batch_updated_wanted --;
  end_transaction (ctrl, 1);
}

/* Suspend any extant batch transaction (it is safe to call this even
   no batch transaction has been started).  Note: you cannot suspend a
   batch transaction if you are in a normal transaction.  The batch
   transaction can be resumed explicitly by calling
   tofu_resume_batch_transaction or implicitly by starting a normal
   transaction.  */
static void
tofu_suspend_batch_transaction (ctrl_t ctrl)
{
  end_transaction (ctrl, 2);
}

/* Resume a batch transaction if there is no extant batch transaction
   and one has been requested using tofu_begin_batch_transaction.  */
static void
tofu_resume_batch_transaction (ctrl_t ctrl)
{
  begin_transaction (ctrl, 1);
}



/* Wrapper around strtol which prints a warning in case of a
 * conversion error.  On success the converted value is stored at
 * R_VALUE and 0 is returned; on error FALLBACK is stored at R_VALUE
 * and an error code is returned.  */
static gpg_error_t
string_to_long (long *r_value, const char *string, long fallback, int line)
{
  gpg_error_t err;
  char *tail = NULL;

  gpg_err_set_errno (0);
  *r_value = strtol (string, &tail, 0);
  if (errno || !(!strcmp (tail, ".0") || !*tail))
    {
      err = errno? gpg_error_from_errno (errno) : gpg_error (GPG_ERR_BAD_DATA);
      log_debug ("%s:%d: "
                 "strtol failed for DB returned string (tail=%.10s): %s\n",
                 __FILE__, line, tail, gpg_strerror (err));
      *r_value = fallback;
    }
  else
    err = 0;

  return err;
}


/* Wrapper around strtoul which prints a warning in case of a
 * conversion error.  On success the converted value is stored at
 * R_VALUE and 0 is returned; on error FALLBACK is stored at R_VALUE
 * and an error code is returned.  */
static gpg_error_t
string_to_ulong (unsigned long *r_value, const char *string,
                 unsigned long fallback, int line)
{
  gpg_error_t err;
  char *tail = NULL;

  gpg_err_set_errno (0);
  *r_value = strtoul (string, &tail, 0);
  if (errno || !(!strcmp (tail, ".0") || !*tail))
    {
      err = errno? gpg_error_from_errno (errno) : gpg_error (GPG_ERR_BAD_DATA);
      log_debug ("%s:%d: "
                 "strtoul failed for DB returned string (tail=%.10s): %s\n",
                 __FILE__, line, tail, gpg_strerror (err));
      *r_value = fallback;
    }
  else
    err = 0;

  return err;
}



/* Collect results of a select count (*) ...; style query.  Aborts if
   the argument is not a valid integer (or real of the form X.0).  */
static int
get_single_unsigned_long_cb (void *cookie, int argc, char **argv,
			     char **azColName)
{
  unsigned long int *count = cookie;

  (void) azColName;

  log_assert (argc == 1);

  if (string_to_ulong (count, argv[0], 0, __LINE__))
    return 1; /* Abort.  */
  return 0;
}

static int
get_single_unsigned_long_cb2 (void *cookie, int argc, char **argv,
			     char **azColName, sqlite3_stmt *stmt)
{
  (void) stmt;
  return get_single_unsigned_long_cb (cookie, argc, argv, azColName);
}

/* We expect a single integer column whose name is "version".  COOKIE
   must point to an int.  This function always aborts.  On error or a
   if the version is bad, sets *VERSION to -1.  */
static int
version_check_cb (void *cookie, int argc, char **argv, char **azColName)
{
  int *version = cookie;

  if (argc != 1 || strcmp (azColName[0], "version") != 0)
    {
      *version = -1;
      return 1;
    }

  if (strcmp (argv[0], "1") == 0)
    *version = 1;
  else
    {
      log_error (_("unsupported TOFU database version: %s\n"), argv[0]);
      *version = -1;
    }

  /* Don't run again.  */
  return 1;
}


/* If the DB is new, initialize it.  Otherwise, check the DB's
   version.

   Return 0 if the database is okay and 1 otherwise.  */
static int
initdb (sqlite3 *db)
{
  char *err = NULL;
  int rc;
  unsigned long int count;
  int version = -1;

  rc = sqlite3_exec (db, "begin transaction;", NULL, NULL, &err);
  if (rc)
    {
      log_error (_("error beginning transaction on TOFU database: %s\n"),
		 err);
      sqlite3_free (err);
      return 1;
    }

  /* If the DB has no tables, then assume this is a new DB that needs
     to be initialized.  */
  rc = sqlite3_exec (db,
		     "select count(*) from sqlite_master where type='table';",
		     get_single_unsigned_long_cb, &count, &err);
  if (rc)
    {
      log_error (_("error reading TOFU database: %s\n"), err);
      print_further_info ("query available tables");
      sqlite3_free (err);
      goto out;
    }
  else if (count != 0)
    /* Assume that the DB is already initialized.  Make sure the
       version is okay.  */
    {
      rc = sqlite3_exec (db, "select version from version;", version_check_cb,
			 &version, &err);
      if (rc == SQLITE_ABORT && version == 1)
	/* Happy, happy, joy, joy.  */
	{
	  sqlite3_free (err);
          rc = 0;
          goto out;
	}
      else if (rc == SQLITE_ABORT && version == -1)
	/* Unsupported version.  */
	{
	  /* An error message was already displayed.  */
	  sqlite3_free (err);
          goto out;
	}
      else if (rc)
	/* Some error.  */
	{
	  log_error (_("error determining TOFU database's version: %s\n"), err);
	  sqlite3_free (err);
          goto out;
	}
      else
        {
          /* Unexpected success.  This can only happen if there are no
             rows.  (select returned 0, but expected ABORT.)  */
	  log_error (_("error determining TOFU database's version: %s\n"),
                     gpg_strerror (GPG_ERR_NO_DATA));
          rc = 1;
          goto out;
	}
    }

  /* Create the version table.  */
  rc = sqlite3_exec (db,
		     "create table version (version INTEGER);",
		     NULL, NULL, &err);
  if (rc)
    {
      log_error (_("error initializing TOFU database: %s\n"), err);
      print_further_info ("create version");
      sqlite3_free (err);
      goto out;
    }

  /* Initialize the version table, which contains a single integer
     value.  */
  rc = sqlite3_exec (db,
		     "insert into version values (1);",
		     NULL, NULL, &err);
  if (rc)
    {
      log_error (_("error initializing TOFU database: %s\n"), err);
      print_further_info ("insert version");
      sqlite3_free (err);
      goto out;
    }

  /* The list of <fingerprint, email> bindings and auxiliary data.
   *
   *  OID is a unique ID identifying this binding (and used by the
   *    signatures table, see below).  Note: OIDs will never be
   *    reused.
   *
   *  FINGERPRINT: The key's fingerprint.
   *
   *  EMAIL: The normalized email address.
   *
   *  USER_ID: The unmodified user id from which EMAIL was extracted.
   *
   *  TIME: The time this binding was first observed.
   *
   *  POLICY: The trust policy (TOFU_POLICY_BAD, etc. as an integer).
   *
   *  CONFLICT is either NULL or a fingerprint.  Assume that we have
   *    a binding <0xdeadbeef, foo@example.com> and then we observe
   *    <0xbaddecaf, foo@example.com>.  There two bindings conflict
   *    (they have the same email address).  When we observe the
   *    latter binding, we warn the user about the conflict and ask
   *    for a policy decision about the new binding.  We also change
   *    the old binding's policy to ask if it was auto.  So that we
   *     know why this occurred, we also set conflict to 0xbaddecaf.
   */
  rc = gpgsql_exec_printf
      (db, NULL, NULL, &err,
       "create table bindings\n"
       " (oid INTEGER PRIMARY KEY AUTOINCREMENT,\n"
       "  fingerprint TEXT, email TEXT, user_id TEXT, time INTEGER,\n"
       "  policy BOOLEAN CHECK (policy in (%d, %d, %d, %d, %d)),\n"
       "  conflict STRING,\n"
       "  unique (fingerprint, email));\n"
       "create index bindings_fingerprint_email\n"
       " on bindings (fingerprint, email);\n"
       "create index bindings_email on bindings (email);\n",
       TOFU_POLICY_AUTO, TOFU_POLICY_GOOD, TOFU_POLICY_UNKNOWN,
       TOFU_POLICY_BAD, TOFU_POLICY_ASK);
  if (rc)
    {
      log_error (_("error initializing TOFU database: %s\n"), err);
      print_further_info ("create bindings");
      sqlite3_free (err);
      goto out;
    }

  /* The signatures that we have observed.
   *
   * BINDING refers to a record in the bindings table, which
   * describes the binding (i.e., this is a foreign key that
   * references bindings.oid).
   *
   * SIG_DIGEST is the digest stored in the signature.
   *
   * SIG_TIME is the timestamp stored in the signature.
   *
   * ORIGIN is a free-form string that describes who fed this
   * signature to GnuPG (e.g., email:claws).
   *
   * TIME is the time this signature was registered.  */
  rc = sqlite3_exec (db,
			 "create table signatures "
			 " (binding INTEGER NOT NULL, sig_digest TEXT,"
			 "  origin TEXT, sig_time INTEGER, time INTEGER,"
			 "  primary key (binding, sig_digest, origin));",
			 NULL, NULL, &err);
  if (rc)
    {
      log_error (_("error initializing TOFU database: %s\n"), err);
      print_further_info ("create signatures");
      sqlite3_free (err);
      goto out;
    }

 out:
  if (! rc)
    {
      /* Early version of the v1 format did not include the encryption
         table.  Add it.  */
      sqlite3_exec (db,
                    "create table if not exists encryptions"
                    " (binding INTEGER NOT NULL,"
                    "  time INTEGER);"
                    "create index if not exists encryptions_binding"
                    " on encryptions (binding);\n",
                    NULL, NULL, &err);
    }

  if (rc)
    {
      rc = sqlite3_exec (db, "rollback;", NULL, NULL, &err);
      if (rc)
	{
	  log_error (_("error rolling back transaction on TOFU database: %s\n"),
		     err);
	  sqlite3_free (err);
	}
      return 1;
    }
  else
    {
      rc = sqlite3_exec (db, "end transaction;", NULL, NULL, &err);
      if (rc)
	{
	  log_error (_("error committing transaction on TOFU database: %s\n"),
		     err);
	  sqlite3_free (err);
	  return 1;
	}
      return 0;
    }
}


/* Create a new DB handle.  Returns NULL on error.  */
/* FIXME: Change to return an error code for better reporting by the
   caller.  */
static tofu_dbs_t
opendbs (ctrl_t ctrl)
{
  char *filename;
  sqlite3 *db;
  int rc;

  if (!ctrl->tofu.dbs)
    {
      filename = make_filename (gnupg_homedir (), "tofu.db", NULL);

      rc = sqlite3_open (filename, &db);
      if (rc)
        {
          log_error (_("error opening TOFU database '%s': %s\n"),
                     filename, sqlite3_errmsg (db));
          /* Even if an error occurs, DB is guaranteed to be valid.  */
          sqlite3_close (db);
          db = NULL;
        }
      xfree (filename);

      /* If a DB is locked wait up to 5 seconds for the lock to be cleared
         before failing.  */
      if (db)
        sqlite3_busy_timeout (db, 5 * 1000);

      if (db && initdb (db))
        {
          sqlite3_close (db);
          db = NULL;
        }

      if (db)
        {
          ctrl->tofu.dbs = xmalloc_clear (sizeof *ctrl->tofu.dbs);
          ctrl->tofu.dbs->db = db;
        }
    }
  else
    log_assert (ctrl->tofu.dbs->db);

  return ctrl->tofu.dbs;
}


/* Release all of the resources associated with the DB handle.  */
void
tofu_closedbs (ctrl_t ctrl)
{
  tofu_dbs_t dbs;
  sqlite3_stmt **statements;

  dbs = ctrl->tofu.dbs;
  if (!dbs)
    return;  /* Not initialized.  */

  log_assert (dbs->in_transaction == 0);

  end_transaction (ctrl, 2);

  /* Arghh, that is a surprising use of the struct.  */
  for (statements = (void *) &dbs->s;
       (void *) statements < (void *) &(&dbs->s)[1];
       statements ++)
    sqlite3_finalize (*statements);

  sqlite3_close (dbs->db);
  xfree (dbs);
  ctrl->tofu.dbs = NULL;
}


/* Collect results of a select min (foo) ...; style query.  Aborts if
   the argument is not a valid integer (or real of the form X.0).  */
static int
get_single_long_cb (void *cookie, int argc, char **argv, char **azColName)
{
  long *count = cookie;

  (void) azColName;

  log_assert (argc == 1);

  if (string_to_long (count, argv[0], 0, __LINE__))
    return 1; /* Abort.  */

  return 0;
}

static int
get_single_long_cb2 (void *cookie, int argc, char **argv, char **azColName,
                     sqlite3_stmt *stmt)
{
  (void) stmt;
  return get_single_long_cb (cookie, argc, argv, azColName);
}

/* Record (or update) a trust policy about a (possibly new)
   binding.

   If SHOW_OLD is set, the binding's old policy is displayed.  */
static gpg_error_t
record_binding (tofu_dbs_t dbs, const char *fingerprint, const char *email,
		const char *user_id, enum tofu_policy policy, int show_old,
                time_t now)
{
  char *fingerprint_pp = format_hexfingerprint (fingerprint, NULL, 0);
  gpg_error_t rc;
  char *err = NULL;

  if (! (policy == TOFU_POLICY_AUTO
	 || policy == TOFU_POLICY_GOOD
	 || policy == TOFU_POLICY_UNKNOWN
	 || policy == TOFU_POLICY_BAD
	 || policy == TOFU_POLICY_ASK))
    log_bug ("%s: Bad value for policy (%d)!\n", __func__, policy);


  if (DBG_TRUST || show_old)
    {
      /* Get the old policy.  Since this is just for informational
       * purposes, there is no need to start a transaction or to die
       * if there is a failure.  */

      /* policy_old needs to be a long and not an enum tofu_policy,
         because we pass it by reference to get_single_long_cb2, which
         expects a long.  */
      long policy_old = TOFU_POLICY_NONE;

      rc = gpgsql_stepx
	(dbs->db, &dbs->s.record_binding_get_old_policy,
         get_single_long_cb2, &policy_old, &err,
	 "select policy from bindings where fingerprint = ? and email = ?",
	 GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_STRING, email,
         GPGSQL_ARG_END);
      if (rc)
	{
	  log_debug ("TOFU: Error reading from binding database"
		     " (reading policy for <key: %s, user id: %s>): %s\n",
		     fingerprint, email, err);
	  sqlite3_free (err);
	}

      if (policy_old != TOFU_POLICY_NONE)
        (show_old ? log_info : log_debug)
          ("Changing TOFU trust policy for binding"
           " <key: %s, user id: %s> from %s to %s.\n",
           fingerprint, show_old ? user_id : email,
           tofu_policy_str (policy_old),
           tofu_policy_str (policy));
      else
        (show_old ? log_info : log_debug)
          ("Setting TOFU trust policy for new binding"
           " <key: %s, user id: %s> to %s.\n",
           fingerprint, show_old ? user_id : email,
           tofu_policy_str (policy));

      if (policy_old == policy)
        {
          rc = 0;
          goto leave; /* Nothing to do.  */
        }
    }

  if (opt.dry_run)
    {
      log_info ("TOFU database update skipped due to --dry-run\n");
      rc = 0;
      goto leave;
    }

  rc = gpgsql_stepx
    (dbs->db, &dbs->s.record_binding_update, NULL, NULL, &err,
     "insert or replace into bindings\n"
     " (oid, fingerprint, email, user_id, time, policy)\n"
     " values (\n"
     /* If we don't explicitly reuse the OID, then SQLite will
	reallocate a new one.  We just need to search for the OID
	based on the fingerprint and email since they are unique.  */
     "  (select oid from bindings where fingerprint = ? and email = ?),\n"
     "  ?, ?, ?, ?, ?);",
     GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_STRING, email,
     GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_STRING, email,
     GPGSQL_ARG_STRING, user_id,
     GPGSQL_ARG_LONG_LONG, (long long) now,
     GPGSQL_ARG_INT, (int) policy,
     GPGSQL_ARG_END);
  if (rc)
    {
      log_error (_("error updating TOFU database: %s\n"), err);
      print_further_info (" insert bindings <key: %s, user id: %s> = %s",
                          fingerprint, email, tofu_policy_str (policy));
      sqlite3_free (err);
      goto leave;
    }

 leave:
  xfree (fingerprint_pp);
  return rc;
}


/* Collect the strings returned by a query in a simply string list.
   Any NULL values are converted to the empty string.

   If a result has 3 rows and each row contains two columns, then the
   results are added to the list as follows (the value is parentheses
   is the 1-based index in the final list):

     row 1, col 2 (6)
     row 1, col 1 (5)
     row 2, col 2 (4)
     row 2, col 1 (3)
     row 3, col 2 (2)
     row 3, col 1 (1)

   This is because add_to_strlist pushes the results onto the front of
   the list.  The end result is that the rows are backwards, but the
   columns are in the expected order.  */
static int
strings_collect_cb (void *cookie, int argc, char **argv, char **azColName)
{
  int i;
  strlist_t *strlist = cookie;

  (void) azColName;

  for (i = argc - 1; i >= 0; i --)
    add_to_strlist (strlist, argv[i] ? argv[i] : "");

  return 0;
}

static int
strings_collect_cb2 (void *cookie, int argc, char **argv, char **azColName,
                     sqlite3_stmt *stmt)
{
  (void) stmt;
  return strings_collect_cb (cookie, argc, argv, azColName);

}

/* Auxiliary data structure to collect statistics about
   signatures.  */
struct signature_stats
{
  struct signature_stats *next;

  /* The user-assigned policy for this binding.  */
  enum tofu_policy policy;

  /* How long ago the signature was created (rounded to a multiple of
     TIME_AGO_UNIT_SMALL, etc.).  */
  long time_ago;
  /* Number of signatures during this time.  */
  unsigned long count;

  /* If the corresponding key/user id has been expired / revoked.  */
  int is_expired;
  int is_revoked;

  /* The key that generated this signature.  */
  char fingerprint[1];
};

static void
signature_stats_free (struct signature_stats *stats)
{
  while (stats)
    {
      struct signature_stats *next = stats->next;
      xfree (stats);
      stats = next;
    }
}

static void
signature_stats_prepend (struct signature_stats **statsp,
			 const char *fingerprint,
			 enum tofu_policy policy,
			 long time_ago,
			 unsigned long count)
{
  struct signature_stats *stats =
    xmalloc_clear (sizeof (*stats) + strlen (fingerprint));

  stats->next = *statsp;
  *statsp = stats;

  strcpy (stats->fingerprint, fingerprint);
  stats->policy = policy;
  stats->time_ago = time_ago;
  stats->count = count;
}


/* Process rows that contain the four columns:

     <fingerprint, policy, time ago, count>.  */
static int
signature_stats_collect_cb (void *cookie, int argc, char **argv,
			    char **azColName, sqlite3_stmt *stmt)
{
  struct signature_stats **statsp = cookie;
  int i = 0;
  enum tofu_policy policy;
  long time_ago;
  unsigned long count;
  long along;

  (void) azColName;
  (void) stmt;

  i ++;

  if (string_to_long (&along, argv[i], 0, __LINE__))
    return 1;  /* Abort */
  policy = along;
  i ++;

  if (! argv[i])
    time_ago = 0;
  else
    {
      if (string_to_long (&time_ago, argv[i], 0, __LINE__))
        return 1; /* Abort.  */
    }
  i ++;

  /* If time_ago is NULL, then we had no messages, but we still have a
     single row, which count(*) turns into 1.  */
  if (! argv[i - 1])
    count = 0;
  else
    {
      if (string_to_ulong (&count, argv[i], 0, __LINE__))
        return 1; /* Abort */
    }
  i ++;

  log_assert (argc == i);

  signature_stats_prepend (statsp, argv[0], policy, time_ago, count);

  return 0;
}

/* Convert from seconds to time units.

   Note: T should already be a multiple of TIME_AGO_UNIT_SMALL or
   TIME_AGO_UNIT_MEDIUM or TIME_AGO_UNIT_LARGE.  */
signed long
time_ago_scale (signed long t)
{
  if (t < TIME_AGO_UNIT_MEDIUM)
    return t / TIME_AGO_UNIT_SMALL;
  if (t < TIME_AGO_UNIT_LARGE)
    return t / TIME_AGO_UNIT_MEDIUM;
  return t / TIME_AGO_UNIT_LARGE;
}


/* Return the policy for the binding <FINGERPRINT, EMAIL> (email has
   already been normalized) and any conflict information in *CONFLICT
   if CONFLICT is not NULL.  Returns _tofu_GET_POLICY_ERROR if an error
   occurs.  */
static enum tofu_policy
get_policy (tofu_dbs_t dbs, const char *fingerprint, const char *email,
	    char **conflict)
{
  int rc;
  char *err = NULL;
  strlist_t strlist = NULL;
  enum tofu_policy policy = _tofu_GET_POLICY_ERROR;
  long along;

  /* Check if the <FINGERPRINT, EMAIL> binding is known
     (TOFU_POLICY_NONE cannot appear in the DB.  Thus, if POLICY is
     still TOFU_POLICY_NONE after executing the query, then the
     result set was empty.)  */
  rc = gpgsql_stepx (dbs->db, &dbs->s.get_policy_select_policy_and_conflict,
                      strings_collect_cb2, &strlist, &err,
                      "select policy, conflict from bindings\n"
                      " where fingerprint = ? and email = ?",
                      GPGSQL_ARG_STRING, fingerprint,
                      GPGSQL_ARG_STRING, email,
                      GPGSQL_ARG_END);
  if (rc)
    {
      log_error (_("error reading TOFU database: %s\n"), err);
      print_further_info ("checking for existing bad bindings");
      sqlite3_free (err);
      goto out;
    }

  if (strlist_length (strlist) == 0)
    /* No results.  */
    {
      policy = TOFU_POLICY_NONE;
      goto out;
    }
  else if (strlist_length (strlist) != 2)
    /* The result has the wrong form.  */
    {
      log_error (_("error reading TOFU database: %s\n"),
                 gpg_strerror (GPG_ERR_BAD_DATA));
      print_further_info ("checking for existing bad bindings:"
                          " expected 2 results, got %d\n",
                          strlist_length (strlist));
      goto out;
    }

  /* The result has the right form.  */

  if (string_to_long (&along, strlist->d, 0, __LINE__))
    {
      log_error (_("error reading TOFU database: %s\n"),
                 gpg_strerror (GPG_ERR_BAD_DATA));
      print_further_info ("bad value for policy: %s", strlist->d);
      goto out;
    }
  policy = along;

  if (! (policy == TOFU_POLICY_AUTO
	 || policy == TOFU_POLICY_GOOD
	 || policy == TOFU_POLICY_UNKNOWN
	 || policy == TOFU_POLICY_BAD
	 || policy == TOFU_POLICY_ASK))
    {
      log_error (_("error reading TOFU database: %s\n"),
                 gpg_strerror (GPG_ERR_DB_CORRUPTED));
      print_further_info ("invalid value for policy (%d)", policy);
      policy = _tofu_GET_POLICY_ERROR;
      goto out;
    }


  /* If CONFLICT is set, then policy should be TOFU_POLICY_ASK.  But,
     just in case, we do the check again here and ignore the conflict
     if POLICY is not TOFU_POLICY_ASK.  */
  if (conflict)
    {
      if (policy == TOFU_POLICY_ASK && *strlist->next->d)
	*conflict = xstrdup (strlist->next->d);
      else
	*conflict = NULL;
    }

 out:
  log_assert (policy == _tofu_GET_POLICY_ERROR
              || policy == TOFU_POLICY_NONE
              || policy == TOFU_POLICY_AUTO
              || policy == TOFU_POLICY_GOOD
              || policy == TOFU_POLICY_UNKNOWN
              || policy == TOFU_POLICY_BAD
              || policy == TOFU_POLICY_ASK);

  free_strlist (strlist);

  return policy;
}


/* Format the first part of a conflict message and return that as a
 * malloced string.  */
static char *
format_conflict_msg_part1 (int policy, strlist_t conflict_set,
                           const char *email)
{
  estream_t fp;
  char *fingerprint;
  char *tmpstr, *text;

  log_assert (conflict_set);
  fingerprint = conflict_set->d;

  fp = es_fopenmem (0, "rw,samethread");
  if (!fp)
    log_fatal ("error creating memory stream: %s\n",
               gpg_strerror (gpg_error_from_syserror()));

  if (policy == TOFU_POLICY_NONE)
    {
      es_fprintf (fp,
                  _("This is the first time the email address \"%s\" is "
                    "being used with key %s."),
                  email, fingerprint);
      es_fputs ("  ", fp);
    }
  else if (policy == TOFU_POLICY_ASK && conflict_set->next)
    {
      int conflicts = strlist_length (conflict_set);
      es_fprintf (fp, _("The email address \"%s\" is associated with %d keys!"),
                  email, conflicts);
      if (opt.verbose)
        es_fprintf (fp,
                    _("  Since this binding's policy was 'auto', it has been "
                      "changed to 'ask'."));
      es_fputs ("  ", fp);
    }

  es_fprintf (fp,
              _("Please indicate whether this email address should"
                " be associated with key %s or whether you think someone"
                " is impersonating \"%s\"."),
              fingerprint, email);
  es_fputc ('\n', fp);

  es_fputc (0, fp);
  if (es_fclose_snatch (fp, (void **)&tmpstr, NULL))
    log_fatal ("error snatching memory stream\n");
  text = format_text (tmpstr, 0, 72, 80);
  es_free (tmpstr);

  return text;
}


/* Return 1 if A signed B and B signed A.  */
static int
cross_sigs (kbnode_t a, kbnode_t b)
{
  int i;

  PKT_public_key *a_pk = a->pkt->pkt.public_key;
  PKT_public_key *b_pk = b->pkt->pkt.public_key;

  char a_keyid[33];
  char b_keyid[33];

  if (DBG_TRUST)
    {
      format_keyid (pk_main_keyid (a_pk),
                    KF_LONG, a_keyid, sizeof (a_keyid));
      format_keyid (pk_main_keyid (b_pk),
                    KF_LONG, b_keyid, sizeof (b_keyid));
    }

  for (i = 0; i < 2; i ++)
    {
      /* See if SIGNER signed SIGNEE.  */

      kbnode_t signer = i == 0 ? a : b;
      kbnode_t signee = i == 0 ? b : a;

      PKT_public_key *signer_pk = signer->pkt->pkt.public_key;
      u32 *signer_kid = pk_main_keyid (signer_pk);
      kbnode_t n;

      /* Iterate over SIGNEE's keyblock and see if there is a valid
         signature from SIGNER.  */
      for (n = signee; n; n = n->next)
        {
          PKT_signature *sig;

          if (n->pkt->pkttype != PKT_SIGNATURE)
            continue;

          sig = n->pkt->pkt.signature;

          if (! (sig->sig_class == 0x10
                 || sig->sig_class == 0x11
                 || sig->sig_class == 0x12
                 || sig->sig_class == 0x13))
            /* Not a signature over a user id.  */
            continue;

          /* SIG is on SIGNEE's keyblock.  If SIG was generated by the
             signer, then it's a match.  */
          if (keyid_cmp (sig->keyid, signer_kid) == 0)
            /* Match!  */
            break;
        }
      if (! n)
        /* We didn't find a signature from signer over signee.  */
        {
          if (DBG_TRUST)
            log_debug ("No cross sig between %s and %s\n",
                       a_keyid, b_keyid);
          return 0;
        }
    }

  /* A signed B and B signed A.  */
  if (DBG_TRUST)
    log_debug ("Cross sig between %s and %s\n",
               a_keyid, b_keyid);

  return 1;
}

/* Return whether the key was signed by an ultimately trusted key.  */
static int
signed_by_utk (kbnode_t a)
{
  kbnode_t n;

  for (n = a; n; n = n->next)
    {
      PKT_signature *sig;

      if (n->pkt->pkttype != PKT_SIGNATURE)
        continue;

      sig = n->pkt->pkt.signature;

      if (! (sig->sig_class == 0x10
             || sig->sig_class == 0x11
             || sig->sig_class == 0x12
             || sig->sig_class == 0x13))
        /* Not a signature over a user id.  */
        continue;

      /* SIG is on SIGNEE's keyblock.  If SIG was generated by the
         signer, then it's a match.  */
      if (tdb_keyid_is_utk (sig->keyid))
        {
          /* Match!  */
          if (DBG_TRUST)
            log_debug ("TOFU: %s is signed by an ultimately trusted key.\n",
                       pk_keyid_str (a->pkt->pkt.public_key));

          return 1;
        }
    }

  if (DBG_TRUST)
    log_debug ("TOFU: %s is NOT signed by an ultimately trusted key.\n",
               pk_keyid_str (a->pkt->pkt.public_key));

  return 0;
}


enum
  {
    BINDING_NEW = 1 << 0,
    BINDING_CONFLICT = 1 << 1,
    BINDING_EXPIRED = 1 << 2,
    BINDING_REVOKED = 1 << 3
  };


/* Ask the user about the binding.  There are three ways we could end
 * up here:
 *
 *   - This is a new binding and there is a conflict
 *     (policy == TOFU_POLICY_NONE && conflict_set_count > 1),
 *
 *   - This is a new binding and opt.tofu_default_policy is set to
 *     ask.  (policy == TOFU_POLICY_NONE && opt.tofu_default_policy ==
 *     TOFU_POLICY_ASK), or,
 *
 *   - The policy is ask (the user deferred last time) (policy ==
 *     TOFU_POLICY_ASK).
 *
 * Note: this function must not be called while in a transaction!
 *
 * CONFLICT_SET includes all of the conflicting bindings
 * with FINGERPRINT first.  FLAGS is a bit-wise or of
 * BINDING_NEW, etc.
 */
static void
ask_about_binding (ctrl_t ctrl,
                   enum tofu_policy *policy,
                   int *trust_level,
                   strlist_t conflict_set,
                   const char *fingerprint,
                   const char *email,
                   const char *user_id,
                   time_t now)
{
  tofu_dbs_t dbs;
  strlist_t iter;
  int conflict_set_count = strlist_length (conflict_set);
  char *sqerr = NULL;
  int rc;
  estream_t fp;
  strlist_t other_user_ids = NULL;
  struct signature_stats *stats = NULL;
  struct signature_stats *stats_iter = NULL;
  char *prompt = NULL;
  char *choices;

  dbs = ctrl->tofu.dbs;
  log_assert (dbs);
  log_assert (dbs->in_transaction == 0);

  fp = es_fopenmem (0, "rw,samethread");
  if (!fp)
    log_fatal ("error creating memory stream: %s\n",
               gpg_strerror (gpg_error_from_syserror()));

  {
    char *text = format_conflict_msg_part1 (*policy, conflict_set, email);
    es_fputs (text, fp);
    es_fputc ('\n', fp);
    xfree (text);
  }

  begin_transaction (ctrl, 0);

  /* Find other user ids associated with this key and whether the
   * bindings are marked as good or bad.  */
  rc = gpgsql_stepx
    (dbs->db, &dbs->s.get_trust_gather_other_user_ids,
     strings_collect_cb2, &other_user_ids, &sqerr,
     "select user_id, policy from bindings where fingerprint = ?;",
     GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_END);
  if (rc)
    {
      log_error (_("error gathering other user IDs: %s\n"), sqerr);
      sqlite3_free (sqerr);
      sqerr = NULL;
    }

  if (other_user_ids)
    {
      strlist_t strlist_iter;

      es_fprintf (fp, _("This key's user IDs:\n"));
      for (strlist_iter = other_user_ids;
           strlist_iter;
           strlist_iter = strlist_iter->next)
        {
          char *other_user_id = strlist_iter->d;
          char *other_thing;
          enum tofu_policy other_policy;

          log_assert (strlist_iter->next);
          strlist_iter = strlist_iter->next;
          other_thing = strlist_iter->d;

          other_policy = atoi (other_thing);

          es_fprintf (fp, "  %s (", other_user_id);
          es_fprintf (fp, _("policy: %s"), tofu_policy_str (other_policy));
          es_fprintf (fp, ")\n");
        }
      es_fprintf (fp, "\n");

      free_strlist (other_user_ids);
    }

  /* Get the stats for all the keys in CONFLICT_SET.  */
  strlist_rev (&conflict_set);
  for (iter = conflict_set; iter && ! rc; iter = iter->next)
    {
#define STATS_SQL(table, time, sign)                         \
         "select fingerprint, policy, time_ago, count(*)\n" \
         " from\n" \
         "  (select bindings.*,\n" \
         "     "sign" case\n" \
         "       when delta ISNULL then 1\n" \
         /* From the future (but if its just a couple of hours in the \
          * future don't turn it into a warning)?  Or should we use \
          * small, medium or large units?  (Note: whatever we do, we \
          * keep the value in seconds.  Then when we group, everything \
          * that rounds to the same number of seconds is grouped.)  */ \
         "      when delta < -("STRINGIFY (TIME_AGO_FUTURE_IGNORE)") then 2\n" \
         "      when delta < ("STRINGIFY (TIME_AGO_SMALL_THRESHOLD)")\n" \
         "       then 3\n" \
         "      when delta < ("STRINGIFY (TIME_AGO_MEDIUM_THRESHOLD)")\n" \
         "       then 4\n" \
         "      when delta < ("STRINGIFY (TIME_AGO_LARGE_THRESHOLD)")\n" \
         "       then 5\n" \
         "      else 6\n" \
         "     end time_ago,\n" \
         "    delta time_ago_raw\n" \
         "   from bindings\n" \
         "   left join\n" \
         "     (select *,\n" \
         "        cast(? - " time " as real) delta\n" \
         "       from " table ") ss\n" \
         "    on ss.binding = bindings.oid)\n" \
         " where email = ? and fingerprint = ?\n" \
         " group by time_ago\n" \
         /* Make sure the current key is first.  */ \
         " order by time_ago desc;\n"

      /* Use the time when we saw the signature, not when the
         signature was created as that can be forged.  */
      rc = gpgsql_stepx
        (dbs->db, &dbs->s.get_trust_gather_signature_stats,
         signature_stats_collect_cb, &stats, &sqerr,
         STATS_SQL ("signatures", "time", ""),
         GPGSQL_ARG_LONG_LONG, (long long) now,
         GPGSQL_ARG_STRING, email,
         GPGSQL_ARG_STRING, iter->d,
         GPGSQL_ARG_END);
      if (rc)
        break;

      if (!stats || strcmp (iter->d, stats->fingerprint) != 0)
        /* No stats for this binding.  Add a dummy entry.  */
        signature_stats_prepend (&stats, iter->d, TOFU_POLICY_AUTO, 1, 1);

      rc = gpgsql_stepx
        (dbs->db, &dbs->s.get_trust_gather_encryption_stats,
         signature_stats_collect_cb, &stats, &sqerr,
         STATS_SQL ("encryptions", "time", "-"),
         GPGSQL_ARG_LONG_LONG, (long long) now,
         GPGSQL_ARG_STRING, email,
         GPGSQL_ARG_STRING, iter->d,
         GPGSQL_ARG_END);
      if (rc)
        break;

#undef STATS_SQL

      if (!stats || strcmp (iter->d, stats->fingerprint) != 0
          || stats->time_ago > 0)
        /* No stats for this binding.  Add a dummy entry.  */
        signature_stats_prepend (&stats, iter->d, TOFU_POLICY_AUTO, -1, 1);
    }
  end_transaction (ctrl, 0);
  strlist_rev (&conflict_set);
  if (rc)
    {
      strlist_t strlist_iter;

      log_error (_("error gathering signature stats: %s\n"), sqerr);
      sqlite3_free (sqerr);
      sqerr = NULL;

      es_fprintf (fp, ngettext("The email address \"%s\" is"
                               " associated with %d key:\n",
                               "The email address \"%s\" is"
                               " associated with %d keys:\n",
                               conflict_set_count),
                  email, conflict_set_count);
      for (strlist_iter = conflict_set;
           strlist_iter;
           strlist_iter = strlist_iter->next)
        es_fprintf (fp, "  %s\n", strlist_iter->d);
    }
  else
    {
      char *key = NULL;
      strlist_t binding;
      int seen_in_past = 0;

      es_fprintf (fp, _("Statistics for keys"
                        " with the email address \"%s\":\n"),
                  email);
      for (stats_iter = stats; stats_iter; stats_iter = stats_iter->next)
        {
#if 0
          log_debug ("%s: time_ago: %ld; count: %ld\n",
                     stats_iter->fingerprint,
                     stats_iter->time_ago,
                     stats_iter->count);
#endif

          if (! key || strcmp (key, stats_iter->fingerprint))
            {
              int this_key;
              char *key_pp;

              key = stats_iter->fingerprint;
              this_key = strcmp (key, fingerprint) == 0;
              key_pp = format_hexfingerprint (key, NULL, 0);
              es_fprintf (fp, "  %s (", key_pp);

              /* Find the associated binding.  */
              for (binding = conflict_set;
                   binding;
                   binding = binding->next)
                if (strcmp (key, binding->d) == 0)
                  break;
              log_assert (binding);

              if ((binding->flags & BINDING_REVOKED))
                {
                  es_fprintf (fp, _("revoked"));
                  es_fprintf (fp, _(", "));
                }
              else if ((binding->flags & BINDING_EXPIRED))
                {
                  es_fprintf (fp, _("expired"));
                  es_fprintf (fp, _(", "));
                }

              if (this_key)
                es_fprintf (fp, _("this key"));
              else
                es_fprintf (fp, _("policy: %s"),
                            tofu_policy_str (stats_iter->policy));
              es_fputs ("):\n", fp);
              xfree (key_pp);

              seen_in_past = 0;
            }

          if (labs(stats_iter->time_ago) == 1)
            {
              /* The 1 in this case is the NULL entry.  */
              log_assert (stats_iter->count == 1);
              stats_iter->count = 0;
            }
          seen_in_past += stats_iter->count;

          es_fputs ("    ", fp);
          /* TANSLATORS: This string is concatenated with one of
           * the day/week/month strings to form one sentence.  */
          if (stats_iter->time_ago > 0)
            es_fprintf (fp, ngettext("Verified %d message",
                                     "Verified %d messages",
                                     seen_in_past), seen_in_past);
          else
            es_fprintf (fp, ngettext("Encrypted %d message",
                                     "Encrypted %d messages",
                                     seen_in_past), seen_in_past);

          if (!stats_iter->count)
            es_fputs (".", fp);
          else if (labs(stats_iter->time_ago) == 2)
            {
              es_fprintf (fp, "in the future.");
              /* Reset it.  */
              seen_in_past = 0;
            }
          else
            {
              if (labs(stats_iter->time_ago) == 3)
                es_fprintf (fp, ngettext(" over the past day.",
                                         " over the past %d days.",
                                         seen_in_past),
                            TIME_AGO_SMALL_THRESHOLD
                            / TIME_AGO_UNIT_SMALL);
              else if (labs(stats_iter->time_ago) == 4)
                es_fprintf (fp, ngettext(" over the past month.",
                                         " over the past %d months.",
                                         seen_in_past),
                            TIME_AGO_MEDIUM_THRESHOLD
                            / TIME_AGO_UNIT_MEDIUM);
              else if (labs(stats_iter->time_ago) == 5)
                es_fprintf (fp, ngettext(" over the past year.",
                                         " over the past %d years.",
                                         seen_in_past),
                            TIME_AGO_LARGE_THRESHOLD
                            / TIME_AGO_UNIT_LARGE);
              else if (labs(stats_iter->time_ago) == 6)
                es_fprintf (fp, _(" in the past."));
              else
                log_assert (! "Broken SQL.\n");
            }
          es_fputs ("\n", fp);
        }
    }

  if (conflict_set_count > 1 || (conflict_set->flags & BINDING_CONFLICT))
    {
      /* This is a conflict.  */

      /* TRANSLATORS: Please translate the text found in the source
       * file below.  We don't directly internationalize that text so
       * that we can tweak it without breaking translations.  */
      char *text = _("TOFU detected a binding conflict");
      char *textbuf;
      if (!strcmp (text, "TOFU detected a binding conflict"))
        {
          /* No translation.  Use the English text.  */
          text =
            "Normally, an email address is associated with a single key.  "
            "However, people sometimes generate a new key if "
            "their key is too old or they think it might be compromised.  "
            "Alternatively, a new key may indicate a man-in-the-middle "
            "attack!  Before accepting this association, you should talk to or "
            "call the person to make sure this new key is legitimate.";
        }
      textbuf = format_text (text, 0, 72, 80);
      es_fprintf (fp, "\n%s\n", textbuf);
      xfree (textbuf);
    }

  es_fputc ('\n', fp);

  /* Add a NUL terminator.  */
  es_fputc (0, fp);
  if (es_fclose_snatch (fp, (void **) &prompt, NULL))
    log_fatal ("error snatching memory stream\n");

  /* I think showing the large message once is sufficient.  If we
   * would move it right before the cpr_get many lines will scroll
   * away and the user might not realize that he merely entered a
   * wrong choise (because he does not see that either).  As a small
   * benefit we allow C-L to redisplay everything.  */
  tty_printf ("%s", prompt);

  /* Suspend any transaction: it could take a while until the user
     responds.  */
  tofu_suspend_batch_transaction (ctrl);
  while (1)
    {
      char *response;

      /* TRANSLATORS: Two letters (normally the lower and upper case
       * version of the hotkey) for each of the five choices.  If
       * there is only one choice in your language, repeat it.  */
      choices = _("gG" "aA" "uU" "rR" "bB");
      if (strlen (choices) != 10)
        log_bug ("Bad TOFU conflict translation!  Please report.");

      response = cpr_get
        ("tofu.conflict",
         _("(G)ood, (A)ccept once, (U)nknown, (R)eject once, (B)ad? "));
      trim_spaces (response);
      cpr_kill_prompt ();
      if (*response == CONTROL_L)
        tty_printf ("%s", prompt);
      else if (!response[0])
        /* Default to unknown.  Don't save it.  */
        {
          tty_printf (_("Defaulting to unknown."));
          *policy = TOFU_POLICY_UNKNOWN;
          break;
        }
      else if (!response[1])
        {
          char *choice = strchr (choices, *response);

          if (choice)
            {
              int c = ((size_t) choice - (size_t) choices) / 2;

              switch (c)
                {
                case 0: /* Good.  */
                  *policy = TOFU_POLICY_GOOD;
                  *trust_level = tofu_policy_to_trust_level (*policy);
                  break;
                case 1: /* Accept once.  */
                  *policy = TOFU_POLICY_ASK;
                  *trust_level = tofu_policy_to_trust_level (TOFU_POLICY_GOOD);
                  break;
                case 2: /* Unknown.  */
                  *policy = TOFU_POLICY_UNKNOWN;
                  *trust_level = tofu_policy_to_trust_level (*policy);
                  break;
                case 3: /* Reject once.  */
                  *policy = TOFU_POLICY_ASK;
                  *trust_level = tofu_policy_to_trust_level (TOFU_POLICY_BAD);
                  break;
                case 4: /* Bad.  */
                  *policy = TOFU_POLICY_BAD;
                  *trust_level = tofu_policy_to_trust_level (*policy);
                  break;
                default:
                  log_bug ("c should be between 0 and 4 but it is %d!", c);
                }

              if (record_binding (dbs, fingerprint, email, user_id,
                                  *policy, 0, now))
                {
                  /* If there's an error registering the
                   * binding, don't save the signature.  */
                  *trust_level = _tofu_GET_TRUST_ERROR;
                }
              break;
            }
        }
      xfree (response);
    }

  tofu_resume_batch_transaction (ctrl);

  xfree (prompt);

  signature_stats_free (stats);
}

/* Return the set of keys that conflict with the binding <fingerprint,
   email> (including the binding itself, which will be first in the
   list).  For each returned key also sets BINDING_NEW, etc.  */
static strlist_t
build_conflict_set (tofu_dbs_t dbs, const char *fingerprint, const char *email)
{
  gpg_error_t rc;
  char *sqerr;
  strlist_t conflict_set = NULL;
  int conflict_set_count;
  strlist_t iter;
  kbnode_t *kb_all;
  KEYDB_HANDLE hd;
  int i;

  /* Get the fingerprints of any bindings that share the email address
   * and whether the bindings have a known conflict.
   *
   * Note: if the binding in question is in the DB, it will also be
   * returned.  Thus, if the result set is empty, then <email,
   * fingerprint> is a new binding.  */
  rc = gpgsql_stepx
    (dbs->db, &dbs->s.get_trust_bindings_with_this_email,
     strings_collect_cb2, &conflict_set, &sqerr,
     "select"
     /* A binding should only appear once, but try not to break in the
      * case of corruption.  */
     "  fingerprint || case sum(conflict ISNULL) when 0 then '' else '!' end"
     " from bindings where email = ?"
     "  group by fingerprint"
     /* Make sure the current key comes first in the result list (if
        it is present).  */
     "  order by fingerprint = ? asc, fingerprint desc;",
     GPGSQL_ARG_STRING, email,
     GPGSQL_ARG_STRING, fingerprint,
     GPGSQL_ARG_END);
  if (rc)
    {
      log_error (_("error reading TOFU database: %s\n"), sqerr);
      print_further_info ("listing fingerprints");
      sqlite3_free (sqerr);
      return NULL;
    }

  /* Set BINDING_CONFLICT if the binding has a known conflict.  This
   * allows us to distinguish between bindings where the user
   * explicitly set the policy to ask and bindings where we set the
   * policy to ask due to a conflict.  */
  for (iter = conflict_set; iter; iter = iter->next)
    {
      int l = strlen (iter->d);
      if (!(l == 2 * MAX_FINGERPRINT_LEN
            || l == 2 * MAX_FINGERPRINT_LEN + 1))
        {
          log_error (_("TOFU db corruption detected.\n"));
          print_further_info ("fingerprint '%s' is not %d characters long",
                              iter->d, 2 * MAX_FINGERPRINT_LEN);
        }

      if (l >= 1 && iter->d[l - 1] == '!')
        {
          iter->flags |= BINDING_CONFLICT;
          /* Remove the !.  */
          iter->d[l - 1] = 0;
        }
    }

  /* If the current binding has not yet been recorded, add it to the
   * list.  (The order by above ensures that if it is present, it will
   * be first.)  */
  if (! (conflict_set && strcmp (conflict_set->d, fingerprint) == 0))
    {
      add_to_strlist (&conflict_set, fingerprint);
      conflict_set->flags |= BINDING_NEW;
    }

  conflict_set_count = strlist_length (conflict_set);

  /* Eliminate false conflicts.  */

  /* If two keys have cross signatures, then they are controlled by
   * the same person and thus are not in conflict.  */
  kb_all = xcalloc (sizeof (kb_all[0]), conflict_set_count);
  hd = keydb_new ();
  for (i = 0, iter = conflict_set;
       i < conflict_set_count;
       i ++, iter = iter->next)
    {
      char *fp = iter->d;
      KEYDB_SEARCH_DESC desc;
      kbnode_t kb;
      PKT_public_key *binding_pk;
      kbnode_t n;
      int found_user_id;

      rc = keydb_search_reset (hd);
      if (rc)
        {
          log_error (_("resetting keydb: %s\n"),
                     gpg_strerror (rc));
          continue;
        }

      rc = classify_user_id (fp, &desc, 0);
      if (rc)
        {
          log_error (_("error parsing key specification '%s': %s\n"),
                     fp, gpg_strerror (rc));
          continue;
        }

      rc = keydb_search (hd, &desc, 1, NULL);
      if (rc)
        {
          /* Note: it is entirely possible that we don't have the key
             corresponding to an entry in the TOFU DB.  This can
             happen if we merge two TOFU DBs, but not the key
             rings.  */
          log_info (_("key \"%s\" not found: %s\n"),
                    fp, gpg_strerror (rc));
          continue;
        }

      rc = keydb_get_keyblock (hd, &kb);
      if (rc)
        {
          log_error (_("error reading keyblock: %s\n"),
                     gpg_strerror (rc));
          print_further_info ("fingerprint: %s", fp);
          continue;
        }

      merge_keys_and_selfsig (kb);

      log_assert (kb->pkt->pkttype == PKT_PUBLIC_KEY);

      kb_all[i] = kb;

      /* Since we have the key block, use this opportunity to figure
       * out if the binding is expired or revoked.  */
      binding_pk = kb->pkt->pkt.public_key;

      /* The binding is always expired/revoked if the key is
       * expired/revoked.  */
      if (binding_pk->has_expired)
        iter->flags &= BINDING_EXPIRED;
      if (binding_pk->flags.revoked)
        iter->flags &= BINDING_REVOKED;

      /* The binding is also expired/revoked if the user id is
       * expired/revoked.  */
      n = kb;
      found_user_id = 0;
      while ((n = find_next_kbnode (n, PKT_USER_ID)) && ! found_user_id)
        {
          PKT_user_id *user_id2 = n->pkt->pkt.user_id;
          char *email2;

          if (user_id2->attrib_data)
            continue;

          email2 = email_from_user_id (user_id2->name);

          if (strcmp (email, email2) == 0)
            {
              found_user_id = 1;

              if (user_id2->is_revoked)
                iter->flags &= BINDING_REVOKED;
              if (user_id2->is_expired)
                iter->flags &= BINDING_EXPIRED;
            }

          xfree (email2);
        }

      if (! found_user_id)
        {
          log_info (_("TOFU db corruption detected.\n"));
          print_further_info ("user id '%s' not on key block '%s'",
                              email, fingerprint);
        }
    }
  keydb_release (hd);

  /* Now that we have the key blocks, check for cross sigs.  */
  {
    int j;
    strlist_t *prevp;
    strlist_t iter_next;
    int die[conflict_set_count];

    memset (die, 0, sizeof (die));

    for (i = 0; i < conflict_set_count; i ++)
      {
        /* Look for cross sigs between this key (i == 0) or a key
         * that has cross sigs with i == 0 (i.e., transitively) */
        if (! (i == 0 || die[i]))
          continue;

        for (j = i + 1; j < conflict_set_count; j ++)
          /* Be careful: we might not have a key block for a key.  */
          if (kb_all[i] && kb_all[j] && cross_sigs (kb_all[i], kb_all[j]))
            die[j] = 1;
      }

    /* Free unconflicting bindings (and all of the key blocks).  */
    for (iter = conflict_set, prevp = &conflict_set, i = 0;
         iter;
         iter = iter_next, i ++)
      {
        iter_next = iter->next;

        release_kbnode (kb_all[i]);

        if (die[i])
          {
            *prevp = iter_next;
            iter->next = NULL;
            free_strlist (iter);
            conflict_set_count --;
          }
        else
          {
            prevp = &iter->next;
          }
      }

    /* We shouldn't have removed the head.  */
    log_assert (conflict_set);
    log_assert (conflict_set_count >= 1);
  }
  xfree (kb_all);

  if (DBG_TRUST)
    {
      log_debug ("binding <key: %s, email: %s> conflicts:\n",
                 fingerprint, email);
      for (iter = conflict_set; iter; iter = iter->next)
        {
          log_debug ("  %s:%s%s%s%s\n",
                     iter->d,
                     (iter->flags & BINDING_NEW) ? " new" : "",
                     (iter->flags & BINDING_CONFLICT) ? " known_conflict" : "",
                     (iter->flags & BINDING_EXPIRED) ? " expired" : "",
                     (iter->flags & BINDING_REVOKED) ? " revoked" : "");
        }
    }

  return conflict_set;
}


/* Return the trust level (TRUST_NEVER, etc.) for the binding
 * <FINGERPRINT, EMAIL> (email is already normalized).  If no policy
 * is registered, returns TOFU_POLICY_NONE.  If an error occurs,
 * returns _tofu_GET_TRUST_ERROR.
 *
 * PK is the public key object for FINGERPRINT.
 *
 * USER_ID is the unadulterated user id.
 *
 * If MAY_ASK is set, then we may interact with the user.  This is
 * necessary if there is a conflict or the binding's policy is
 * TOFU_POLICY_ASK.  In the case of a conflict, we set the new
 * conflicting binding's policy to TOFU_POLICY_ASK.  In either case,
 * we return TRUST_UNDEFINED.  Note: if MAY_ASK is set, then this
 * function must not be called while in a transaction!  */
static enum tofu_policy
get_trust (ctrl_t ctrl, PKT_public_key *pk,
           const char *fingerprint, const char *email,
	   const char *user_id, int may_ask, time_t now)
{
  tofu_dbs_t dbs = ctrl->tofu.dbs;
  int in_transaction = 0;
  enum tofu_policy policy;
  int rc;
  char *sqerr = NULL;
  int change_conflicting_to_ask = 0;
  strlist_t conflict_set = NULL;
  int conflict_set_count;
  int trust_level = TRUST_UNKNOWN;
  strlist_t iter;

  log_assert (dbs);

  if (may_ask)
    log_assert (dbs->in_transaction == 0);

  if (opt.batch)
    may_ask = 0;

  log_assert (keyid_cmp (pk_keyid (pk), pk_main_keyid (pk)) == 0);

  /* Make sure _tofu_GET_TRUST_ERROR isn't equal to any of the trust
     levels.  */
  log_assert (_tofu_GET_TRUST_ERROR != TRUST_UNKNOWN
              && _tofu_GET_TRUST_ERROR != TRUST_EXPIRED
              && _tofu_GET_TRUST_ERROR != TRUST_UNDEFINED
              && _tofu_GET_TRUST_ERROR != TRUST_NEVER
              && _tofu_GET_TRUST_ERROR != TRUST_MARGINAL
              && _tofu_GET_TRUST_ERROR != TRUST_FULLY
              && _tofu_GET_TRUST_ERROR != TRUST_ULTIMATE);

  begin_transaction (ctrl, 0);
  in_transaction = 1;

  policy = get_policy (dbs, fingerprint, email, NULL);
  {
    /* See if the key is ultimately trusted.  If so, we're done.  */
    u32 kid[2];

    keyid_from_pk (pk, kid);

    if (tdb_keyid_is_utk (kid))
      {
        if (policy == TOFU_POLICY_NONE)
          /* New binding.  */
          {
            if (record_binding (dbs, fingerprint, email, user_id,
                                TOFU_POLICY_GOOD, 0, now) != 0)
              {
                log_error (_("error setting TOFU binding's trust level"
                             " to %s\n"), "good");
                trust_level = _tofu_GET_TRUST_ERROR;
                goto out;
              }
          }

        trust_level = TRUST_ULTIMATE;
        goto out;
      }
  }

  if (policy == TOFU_POLICY_AUTO)
    {
      policy = opt.tofu_default_policy;
      if (DBG_TRUST)
	log_debug ("TOFU: binding <key: %s, user id: %s>'s policy is"
                   " auto (default: %s).\n",
		   fingerprint, email,
		   tofu_policy_str (opt.tofu_default_policy));
    }
  switch (policy)
    {
    case TOFU_POLICY_AUTO:
    case TOFU_POLICY_GOOD:
    case TOFU_POLICY_UNKNOWN:
    case TOFU_POLICY_BAD:
      /* The saved judgement is auto -> auto, good, unknown or bad.
       * We don't need to ask the user anything.  */
      if (DBG_TRUST)
	log_debug ("TOFU: Known binding <key: %s, user id: %s>'s policy: %s\n",
		   fingerprint, email, tofu_policy_str (policy));
      trust_level = tofu_policy_to_trust_level (policy);
      goto out;

    case TOFU_POLICY_ASK:
      /* We need to ask the user what to do.  Case #1 or #2 below.  */
      if (! may_ask)
	{
	  trust_level = TRUST_UNDEFINED;
	  goto out;
	}

      break;

    case TOFU_POLICY_NONE:
      /* The binding is new, we need to check for conflicts.  Case #3
       * below.  */
      break;

    case _tofu_GET_POLICY_ERROR:
      trust_level = _tofu_GET_TRUST_ERROR;
      goto out;

    default:
      log_bug ("%s: Impossible value for policy (%d)\n", __func__, policy);
    }


  /* We get here if:
   *
   *   1. The saved policy is auto and the default policy is ask
   *      (get_policy() == TOFU_POLICY_AUTO
   *       && opt.tofu_default_policy == TOFU_POLICY_ASK)
   *
   *   2. The saved policy is ask (either last time the user selected
   *      accept once or reject once or there was a conflict and this
   *      binding's policy was changed from auto to ask)
   *      (policy == TOFU_POLICY_ASK), or,
   *
   *   3. We don't have a saved policy (policy == TOFU_POLICY_NONE)
   *      (need to check for a conflict).
   *
   * In summary: POLICY is ask or none.
   */

  /* Before continuing, see if the key is signed by an ultimately
   * trusted key.  */
  {
    int fingerprint_raw_len = strlen (fingerprint) / 2;
    char fingerprint_raw[fingerprint_raw_len];
    int len = 0;
    int is_signed_by_utk = 0;

    if (fingerprint_raw_len != 20
        || ((len = hex2bin (fingerprint,
                            fingerprint_raw, fingerprint_raw_len))
            != strlen (fingerprint)))
      {
        if (DBG_TRUST)
          log_debug ("TOFU: Bad fingerprint: %s (len: %zd, parsed: %d)\n",
                     fingerprint, strlen (fingerprint), len);
      }
    else
      {
        int lookup_err;
        kbnode_t kb;

        lookup_err = get_pubkey_byfprint (NULL, &kb,
                                          fingerprint_raw,
                                          fingerprint_raw_len);
        if (lookup_err)
          {
            if (DBG_TRUST)
              log_debug ("TOFU: Looking up %s: %s\n",
                         fingerprint, gpg_strerror (lookup_err));
          }
        else
          {
            is_signed_by_utk = signed_by_utk (kb);
            release_kbnode (kb);
          }
      }

    if (is_signed_by_utk)
      {
        if (record_binding (dbs, fingerprint, email, user_id,
                            TOFU_POLICY_GOOD, 0, now) != 0)
          {
            log_error (_("error setting TOFU binding's trust level"
                         " to %s\n"), "good");
            trust_level = _tofu_GET_TRUST_ERROR;
          }
        else
          trust_level = TRUST_FULLY;

        goto out;
      }
  }


  /* Look for conflicts.  This is needed in all 3 cases.  */
  conflict_set = build_conflict_set (dbs, fingerprint, email);
  conflict_set_count = strlist_length (conflict_set);
  if (conflict_set_count == 0)
    {
      /* We should always at least have the current binding.  */
      trust_level = _tofu_GET_TRUST_ERROR;
      goto out;
    }

  if (conflict_set_count == 1
      && (conflict_set->flags & BINDING_NEW)
      && opt.tofu_default_policy != TOFU_POLICY_ASK)
    {
      /* We've never observed a binding with this email address and we
       * have a default policy, which is not to ask the user.  */

      /* If we've seen this binding, then we've seen this email and
       * policy couldn't possibly be TOFU_POLICY_NONE.  */
      log_assert (policy == TOFU_POLICY_NONE);

      if (DBG_TRUST)
	log_debug ("TOFU: New binding <key: %s, user id: %s>, no conflict.\n",
		   fingerprint, email);

      if (record_binding (dbs, fingerprint, email, user_id,
			  TOFU_POLICY_AUTO, 0, now) != 0)
	{
	  log_error (_("error setting TOFU binding's trust level to %s\n"),
		       "auto");
	  trust_level = _tofu_GET_TRUST_ERROR;
	  goto out;
	}

      trust_level = tofu_policy_to_trust_level (TOFU_POLICY_AUTO);
      goto out;
    }

  if (conflict_set_count == 1
      && (conflict_set->flags & BINDING_CONFLICT))
    {
      /* No known conflicts now, but there was a conflict.  This means
       * at somepoint, there was a conflict and we changed this
       * binding's policy to ask and set the conflicting key.  The
       * conflict can go away if there is not a cross sig between the
       * two keys.  In this case, just silently clear the conflict and
       * reset the policy to auto.  */

      log_assert (policy == TOFU_POLICY_ASK);

      if (DBG_TRUST)
        log_debug ("TOFU: binding <key: %s, user id: %s> had a conflict, but it's been resolved (probably via  cross sig).\n",
                   fingerprint, email);

      if (record_binding (dbs, fingerprint, email, user_id,
			  TOFU_POLICY_AUTO, 0, now) != 0)
	log_error (_("error setting TOFU binding's trust level to %s\n"),
		   "auto");

      trust_level = tofu_policy_to_trust_level (TOFU_POLICY_AUTO);
      goto out;
    }

  /* We have a conflict.  Mark any conflicting bindings that have an
   * automatic policy as now requiring confirmation.  Note: we delay
   * this until after we ask for confirmation so that when the current
   * policy is printed, it is correct.  */
  change_conflicting_to_ask = 1;

  if (! may_ask)
    {
      /* We can only get here in the third case (no saved policy) and
       * if there is a conflict.  (If the policy was ask (cases #1 and
       * #2) and we weren't allowed to ask, we'd have already exited).  */
      log_assert (policy == TOFU_POLICY_NONE);

      if (record_binding (dbs, fingerprint, email, user_id,
			  TOFU_POLICY_ASK, 0, now) != 0)
	log_error (_("error setting TOFU binding's trust level to %s\n"),
		   "ask");

      trust_level = TRUST_UNDEFINED;
      goto out;
    }

  /* We can't be in a normal transaction in ask_about_binding.  */
  end_transaction (ctrl, 0);
  in_transaction = 0;

  /* If we get here, we need to ask the user about the binding.  */
  ask_about_binding (ctrl,
                     &policy,
                     &trust_level,
                     conflict_set,
                     fingerprint,
                     email,
                     user_id,
                     now);

 out:

  if (change_conflicting_to_ask)
    {
      /* Mark any conflicting bindings that have an automatic policy as
       * now requiring confirmation.  */

      if (! in_transaction)
        {
          begin_transaction (ctrl, 0);
          in_transaction = 1;
        }

      /* If we weren't allowed to ask, also update this key as
       * conflicting with itself.  */
      for (iter = may_ask ? conflict_set->next : conflict_set;
           iter; iter = iter->next)
        {
          rc = gpgsql_exec_printf
            (dbs->db, NULL, NULL, &sqerr,
             "update bindings set policy = %d, conflict = %Q"
             " where email = %Q and fingerprint = %Q and policy = %d;",
             TOFU_POLICY_ASK, fingerprint,
             email, iter->d, TOFU_POLICY_AUTO);
          if (rc)
            {
              log_error (_("error changing TOFU policy: %s\n"), sqerr);
              print_further_info ("binding: <key: %s, user id: %s>",
                                  fingerprint, user_id);
              sqlite3_free (sqerr);
              sqerr = NULL;
            }
          else if (DBG_TRUST)
            log_debug ("Set %s to conflict with %s\n",
                       iter->d, fingerprint);
        }
    }

  if (in_transaction)
    end_transaction (ctrl, 0);

  free_strlist (conflict_set);

  return trust_level;
}


/* Return a malloced string of the form
 *    "7 months, 1 day, 5 minutes, 0 seconds"
 * The caller should replace all '~' in the returned string by a space
 * and also free the returned string.
 *
 * This is actually a bad hack which may not work correctly with all
 * languages.
 */
static char *
time_ago_str (long long int t)
{
  estream_t fp;
  int years = 0;
  int months = 0;
  int days = 0;
  int hours = 0;
  int minutes = 0;
  int seconds = 0;

  /* The number of units that we've printed so far.  */
  int count = 0;
  /* The first unit that we printed (year = 0, month = 1,
     etc.).  */
  int first = -1;
  /* The current unit.  */
  int i = 0;

  char *str;

  /* It would be nice to use a macro to do this, but gettext
     works on the unpreprocessed code.  */
#define MIN_SECS (60)
#define HOUR_SECS (60 * MIN_SECS)
#define DAY_SECS (24 * HOUR_SECS)
#define MONTH_SECS (30 * DAY_SECS)
#define YEAR_SECS (365 * DAY_SECS)

  if (t > YEAR_SECS)
    {
      years = t / YEAR_SECS;
      t -= years * YEAR_SECS;
    }
  if (t > MONTH_SECS)
    {
      months = t / MONTH_SECS;
      t -= months * MONTH_SECS;
    }
  if (t > DAY_SECS)
    {
      days = t / DAY_SECS;
      t -= days * DAY_SECS;
    }
  if (t > HOUR_SECS)
    {
      hours = t / HOUR_SECS;
      t -= hours * HOUR_SECS;
    }
  if (t > MIN_SECS)
    {
      minutes = t / MIN_SECS;
      t -= minutes * MIN_SECS;
    }
  seconds = t;

#undef MIN_SECS
#undef HOUR_SECS
#undef DAY_SECS
#undef MONTH_SECS
#undef YEAR_SECS

  fp = es_fopenmem (0, "rw,samethread");
  if (! fp)
    log_fatal ("error creating memory stream: %s\n",
               gpg_strerror (gpg_error_from_syserror()));

  if (years)
    {
      /* TRANSLATORS: The tilde ('~') is used here to indicate a
       * non-breakable space  */
      es_fprintf (fp, ngettext("%d~year", "%d~years", years), years);
      count ++;
      first = i;
    }
  i ++;
  if ((first == -1 || i - first <= 3) && count <= 0 && months)
    {
      if (count)
        es_fprintf (fp, ", ");
      es_fprintf (fp, ngettext("%d~month", "%d~months", months), months);
      count ++;
      first = i;
    }
  i ++;
  if ((first == -1 || i - first <= 3) && count <= 0 && days)
    {
      if (count)
        es_fprintf (fp, ", ");
      es_fprintf (fp, ngettext("%d~day", "%d~days", days), days);
      count ++;
      first = i;
    }
  i ++;
  if ((first == -1 || i - first <= 3) && count <= 0 && hours)
    {
      if (count)
        es_fprintf (fp, ", ");
      es_fprintf (fp, ngettext("%d~hour", "%d~hours", hours), hours);
      count ++;
      first = i;
    }
  i ++;
  if ((first == -1 || i - first <= 3) && count <= 0 && minutes)
    {
      if (count)
        es_fprintf (fp, ", ");
      es_fprintf (fp, ngettext("%d~minute", "%d~minutes", minutes), minutes);
      count ++;
      first = i;
    }
  i ++;
  if ((first == -1 || i - first <= 3) && count <= 0)
    {
      if (count)
        es_fprintf (fp, ", ");
      es_fprintf (fp, ngettext("%d~second", "%d~seconds", seconds), seconds);
    }

  es_fputc (0, fp);
  if (es_fclose_snatch (fp, (void **) &str, NULL))
    log_fatal ("error snatching memory stream\n");

  return str;
}


/* If FP is NULL, write TOFU_STATS status line.  If FP is not NULL
 * write a "tfs" record to that stream. */
static void
write_stats_status (estream_t fp,
                    enum tofu_policy policy,
                    unsigned long signature_count,
                    unsigned long signature_first_seen,
                    unsigned long signature_most_recent,
                    unsigned long encryption_count,
                    unsigned long encryption_first_done,
                    unsigned long encryption_most_recent)
{
  const char *validity;
  unsigned long messages;

  /* Use the euclidean distance (m = sqrt(a^2 + b^2)) rather then the
     sum of the magnitudes (m = a + b) to ensure a balance between
     verified signatures and encrypted messages.  */
  messages = sqrtu32 (signature_count * signature_count
                      + encryption_count * encryption_count);

  if (messages < 1)
    validity = "1"; /* Key without history.  */
  else if (messages < 2 * BASIC_TRUST_THRESHOLD)
    validity = "2"; /* Key with too little history.  */
  else if (messages < 2 * FULL_TRUST_THRESHOLD)
    validity = "3"; /* Key with enough history for basic trust.  */
  else
    validity = "4"; /* Key with a lot of history.  */

  if (fp)
    {
      es_fprintf (fp, "tfs:1:%s:%lu:%lu:%s:%lu:%lu:%lu:%lu:\n",
                  validity, signature_count, encryption_count,
                  tofu_policy_str (policy),
                  signature_first_seen, signature_most_recent,
                  encryption_first_done, encryption_most_recent);
    }
  else
    {
      write_status_printf (STATUS_TOFU_STATS,
                           "%s %lu %lu %s %lu %lu %lu %lu",
                           validity,
                           signature_count,
                           encryption_count,
                           tofu_policy_str (policy),
                           signature_first_seen,
                           signature_most_recent,
                           encryption_first_done,
                           encryption_most_recent);
    }
}

/* Note: If OUTFP is not NULL, this function merely prints a "tfs" record
 * to OUTFP.  In this case USER_ID is not required.
 *
 * Returns whether the caller should call show_warning after iterating
 * over all user ids.
 */
static int
show_statistics (tofu_dbs_t dbs, const char *fingerprint,
		 const char *email, const char *user_id,
		 estream_t outfp, time_t now)
{
  enum tofu_policy policy = get_policy (dbs, fingerprint, email, NULL);

  char *fingerprint_pp;
  int rc;
  strlist_t strlist = NULL;
  char *err = NULL;

  unsigned long signature_first_seen = 0;
  unsigned long signature_most_recent = 0;
  unsigned long signature_count = 0;
  unsigned long encryption_first_done = 0;
  unsigned long encryption_most_recent = 0;
  unsigned long encryption_count = 0;

  int show_warning = 0;

  (void) user_id;

  fingerprint_pp = format_hexfingerprint (fingerprint, NULL, 0);

  /* Get the signature stats.  */
  rc = gpgsql_exec_printf
    (dbs->db, strings_collect_cb, &strlist, &err,
     "select count (*), min (signatures.time), max (signatures.time)\n"
     " from signatures\n"
     " left join bindings on signatures.binding = bindings.oid\n"
     " where fingerprint = %Q and email = %Q;",
     fingerprint, email);
  if (rc)
    {
      log_error (_("error reading TOFU database: %s\n"), err);
      print_further_info ("getting signature statistics");
      sqlite3_free (err);
      goto out;
    }

  if (strlist)
    {
      /* We expect exactly 3 elements.  */
      log_assert (strlist->next);
      log_assert (strlist->next->next);
      log_assert (! strlist->next->next->next);

      string_to_ulong (&signature_count, strlist->d, -1, __LINE__);
      string_to_ulong (&signature_first_seen, strlist->next->d, -1, __LINE__);
      string_to_ulong (&signature_most_recent,
                       strlist->next->next->d, -1, __LINE__);

      free_strlist (strlist);
      strlist = NULL;
    }

  /* Get the encryption stats.  */
  rc = gpgsql_exec_printf
    (dbs->db, strings_collect_cb, &strlist, &err,
     "select count (*), min (encryptions.time), max (encryptions.time)\n"
     " from encryptions\n"
     " left join bindings on encryptions.binding = bindings.oid\n"
     " where fingerprint = %Q and email = %Q;",
     fingerprint, email);
  if (rc)
    {
      log_error (_("error reading TOFU database: %s\n"), err);
      print_further_info ("getting encryption statistics");
      sqlite3_free (err);
      goto out;
    }

  if (strlist)
    {
      /* We expect exactly 3 elements.  */
      log_assert (strlist->next);
      log_assert (strlist->next->next);
      log_assert (! strlist->next->next->next);

      string_to_ulong (&encryption_count, strlist->d, -1, __LINE__);
      string_to_ulong (&encryption_first_done, strlist->next->d, -1, __LINE__);
      string_to_ulong (&encryption_most_recent,
                       strlist->next->next->d, -1, __LINE__);

      free_strlist (strlist);
      strlist = NULL;
    }

  if (!outfp)
    write_status_text_and_buffer (STATUS_TOFU_USER, fingerprint,
                                  email, strlen (email), 0);

  write_stats_status (outfp, policy,
                      signature_count,
                      signature_first_seen,
                      signature_most_recent,
                      encryption_count,
                      encryption_first_done,
                      encryption_most_recent);

  if (!outfp)
    {
      estream_t fp;
      char *msg;

      fp = es_fopenmem (0, "rw,samethread");
      if (! fp)
        log_fatal ("error creating memory stream: %s\n",
                   gpg_strerror (gpg_error_from_syserror()));

      es_fprintf (fp, _("%s: "), email);

      if (signature_count == 0)
        {
          es_fprintf (fp, _("Verified %ld signatures"), 0L);
          es_fputc ('\n', fp);
        }
      else
        {
          char *first_seen_ago_str = time_ago_str (now - signature_first_seen);

          /* TRANSLATORS: The final %s is replaced by a string like
             "7 months, 1 day, 5 minutes, 0 seconds". */
          es_fprintf (fp,
                      ngettext("Verified %ld signature in the past %s",
                               "Verified %ld signatures in the past %s",
                               signature_count),
                      signature_count, first_seen_ago_str);

          xfree (first_seen_ago_str);
        }

      if (encryption_count == 0)
        {
          es_fprintf (fp, _(", and encrypted %ld messages"), 0L);
        }
      else
        {
          char *first_done_ago_str = time_ago_str (now - encryption_first_done);

          /* TRANSLATORS: The final %s is replaced by a string like
             "7 months, 1 day, 5 minutes, 0 seconds". */
          es_fprintf (fp,
                      ngettext(", and encrypted %ld message in the past %s",
                               ", and encrypted %ld messages in the past %s",
                               encryption_count),
                      encryption_count, first_done_ago_str);

          xfree (first_done_ago_str);
        }

      if (opt.verbose)
        {
          es_fputs ("  ", fp);
          es_fputc ('(', fp);
          es_fprintf (fp, _("policy: %s"), tofu_policy_str (policy));
          es_fputs (").\n", fp);
        }
      else
        es_fputs (".\n", fp);


      {
        char *tmpmsg, *p;
        es_fputc (0, fp);
        if (es_fclose_snatch (fp, (void **) &tmpmsg, NULL))
          log_fatal ("error snatching memory stream\n");
        msg = format_text (tmpmsg, 0, 72, 80);
        es_free (tmpmsg);

        /* Print a status line but suppress the trailing LF.
         * Spaces are not percent escaped. */
        if (*msg)
          write_status_buffer (STATUS_TOFU_STATS_LONG,
                               msg, strlen (msg)-1, -1);

        /* Remove the non-breaking space markers.  */
        for (p=msg; *p; p++)
          if (*p == '~')
            *p = ' ';
      }

      log_string (GPGRT_LOG_INFO, msg);
      xfree (msg);

      if (policy == TOFU_POLICY_AUTO)
        {
          if (signature_count == 0)
            log_info (_("Warning: we have yet to see"
                        " a message signed using this key and user id!\n"));
          else if (signature_count == 1)
            log_info (_("Warning: we've only seen one message"
                        " signed using this key and user id!\n"));

          if (encryption_count == 0)
            log_info (_("Warning: you have yet to encrypt"
                        " a message to this key!\n"));
          else if (encryption_count == 1)
            log_info (_("Warning: you have only encrypted"
                        " one message to this key!\n"));

          /* Cf. write_stats_status  */
          if (sqrtu32 (encryption_count * encryption_count
                       + signature_count * signature_count)
              < 2 * BASIC_TRUST_THRESHOLD)
            show_warning = 1;
        }
    }

 out:
  xfree (fingerprint_pp);

  return show_warning;
}

static void
show_warning (const char *fingerprint, strlist_t user_id_list)
{
  char *set_policy_command;
  char *text;
  char *tmpmsg;

  set_policy_command =
    xasprintf ("gpg --tofu-policy bad %s", fingerprint);

  tmpmsg = xasprintf
    (ngettext
     ("Warning: if you think you've seen more signatures "
      "by this key and user id, then this key might be a "
      "forgery!  Carefully examine the email address for small "
      "variations.  If the key is suspect, then use\n"
      "  %s\n"
      "to mark it as being bad.\n",
      "Warning: if you think you've seen more signatures "
      "by this key and these user ids, then this key might be a "
      "forgery!  Carefully examine the email addresses for small "
      "variations.  If the key is suspect, then use\n"
      "  %s\n"
      "to mark it as being bad.\n",
      strlist_length (user_id_list)),
     set_policy_command);

  text = format_text (tmpmsg, 0, 72, 80);
  xfree (tmpmsg);
  log_string (GPGRT_LOG_INFO, text);
  xfree (text);

  es_free (set_policy_command);
}


/* Extract the email address from a user id and normalize it.  If the
   user id doesn't contain an email address, then we use the whole
   user_id and normalize that.  The returned string must be freed.  */
static char *
email_from_user_id (const char *user_id)
{
  char *email = mailbox_from_userid (user_id);
  if (! email)
    {
      /* Hmm, no email address was provided or we are out of core.  Just
         take the lower-case version of the whole user id.  It could be
         a hostname, for instance.  */
      email = ascii_strlwr (xstrdup (user_id));
    }

  return email;
}

/* Register the signature with the bindings <fingerprint, USER_ID>,
   for each USER_ID in USER_ID_LIST.  The fingerprint is taken from
   the primary key packet PK.

   SIG_DIGEST_BIN is the binary representation of the message's
   digest.  SIG_DIGEST_BIN_LEN is its length.

   SIG_TIME is the time that the signature was generated.

   ORIGIN is a free-formed string describing the origin of the
   signature.  If this was from an email and the Claws MUA was used,
   then this should be something like: "email:claws".  If this is
   NULL, the default is simply "unknown".

   If MAY_ASK is 1, then this function may interact with the user.
   This is necessary if there is a conflict or the binding's policy is
   TOFU_POLICY_ASK.

   This function returns 0 on success and an error code if an error
   occurred.  */
gpg_error_t
tofu_register_signature (ctrl_t ctrl,
                         PKT_public_key *pk, strlist_t user_id_list,
                         const byte *sig_digest_bin, int sig_digest_bin_len,
                         time_t sig_time, const char *origin)
{
  time_t now = gnupg_get_time ();
  gpg_error_t rc;
  tofu_dbs_t dbs;
  char *fingerprint = NULL;
  strlist_t user_id;
  char *email = NULL;
  char *err = NULL;
  char *sig_digest;
  unsigned long c;

  dbs = opendbs (ctrl);
  if (! dbs)
    {
      rc = gpg_error (GPG_ERR_GENERAL);
      log_error (_("error opening TOFU database: %s\n"),
                 gpg_strerror (rc));
      return rc;
    }

  /* We do a query and then an insert.  Make sure they are atomic
     by wrapping them in a transaction.  */
  rc = begin_transaction (ctrl, 0);
  if (rc)
    return rc;

  log_assert (keyid_cmp (pk_keyid (pk), pk_main_keyid (pk)) == 0);

  sig_digest = make_radix64_string (sig_digest_bin, sig_digest_bin_len);
  fingerprint = hexfingerprint (pk, NULL, 0);

  if (! origin)
    /* The default origin is simply "unknown".  */
    origin = "unknown";

  for (user_id = user_id_list; user_id; user_id = user_id->next)
    {
      email = email_from_user_id (user_id->d);

      if (DBG_TRUST)
	log_debug ("TOFU: Registering signature %s with binding"
                   " <key: %s, user id: %s>\n",
		   sig_digest, fingerprint, email);

      /* Make sure the binding exists and record any TOFU
         conflicts.  */
      if (get_trust (ctrl, pk, fingerprint, email, user_id->d, 0, now)
          == _tofu_GET_TRUST_ERROR)
        {
          rc = gpg_error (GPG_ERR_GENERAL);
          xfree (email);
          break;
        }

      /* If we've already seen this signature before, then don't add
         it again.  */
      rc = gpgsql_stepx
        (dbs->db, &dbs->s.register_already_seen,
         get_single_unsigned_long_cb2, &c, &err,
         "select count (*)\n"
         " from signatures left join bindings\n"
         "  on signatures.binding = bindings.oid\n"
         " where fingerprint = ? and email = ? and sig_time = ?\n"
         "  and sig_digest = ?",
         GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_STRING, email,
         GPGSQL_ARG_LONG_LONG, (long long) sig_time,
         GPGSQL_ARG_STRING, sig_digest,
         GPGSQL_ARG_END);
      if (rc)
        {
          log_error (_("error reading TOFU database: %s\n"), err);
          print_further_info ("checking existence");
          sqlite3_free (err);
        }
      else if (c > 1)
        /* Duplicates!  This should not happen.  In particular,
           because <fingerprint, email, sig_time, sig_digest> is the
           primary key!  */
        log_debug ("SIGNATURES DB contains duplicate records"
                   " <key: %s, email: %s, time: 0x%lx, sig: %s,"
                   " origin: %s>."
                   "  Please report.\n",
                   fingerprint, email, (unsigned long) sig_time,
                   sig_digest, origin);
      else if (c == 1)
        {
          if (DBG_TRUST)
            log_debug ("Already observed the signature and binding"
                       " <key: %s, email: %s, time: 0x%lx, sig: %s,"
                       " origin: %s>\n",
                       fingerprint, email, (unsigned long) sig_time,
                       sig_digest, origin);
        }
      else if (opt.dry_run)
        {
          log_info ("TOFU database update skipped due to --dry-run\n");
        }
      else
        /* This is the first time that we've seen this signature and
           binding.  Record it.  */
        {
          if (DBG_TRUST)
            log_debug ("TOFU: Saving signature"
                       " <key: %s, user id: %s, sig: %s>\n",
                       fingerprint, email, sig_digest);

          log_assert (c == 0);

          rc = gpgsql_stepx
            (dbs->db, &dbs->s.register_insert, NULL, NULL, &err,
             "insert into signatures\n"
             " (binding, sig_digest, origin, sig_time, time)\n"
             " values\n"
             " ((select oid from bindings\n"
             "    where fingerprint = ? and email = ?),\n"
             "  ?, ?, ?, ?);",
             GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_STRING, email,
             GPGSQL_ARG_STRING, sig_digest, GPGSQL_ARG_STRING, origin,
             GPGSQL_ARG_LONG_LONG, (long long) sig_time,
             GPGSQL_ARG_LONG_LONG, (long long) now,
             GPGSQL_ARG_END);
          if (rc)
            {
              log_error (_("error updating TOFU database: %s\n"), err);
              print_further_info ("insert signatures");
              sqlite3_free (err);
            }
        }

      xfree (email);

      if (rc)
        break;
    }

  if (rc)
    rollback_transaction (ctrl);
  else
    rc = end_transaction (ctrl, 0);

  xfree (fingerprint);
  xfree (sig_digest);

  return rc;
}

gpg_error_t
tofu_register_encryption (ctrl_t ctrl,
                          PKT_public_key *pk, strlist_t user_id_list,
                          int may_ask)
{
  time_t now = gnupg_get_time ();
  gpg_error_t rc = 0;
  tofu_dbs_t dbs;
  kbnode_t kb = NULL;
  int free_user_id_list = 0;
  char *fingerprint = NULL;
  strlist_t user_id;
  char *err = NULL;

  dbs = opendbs (ctrl);
  if (! dbs)
    {
      rc = gpg_error (GPG_ERR_GENERAL);
      log_error (_("error opening TOFU database: %s\n"),
                 gpg_strerror (rc));
      return rc;
    }

  if (/* We need the key block to find the primary key.  */
      keyid_cmp (pk_keyid (pk), pk_main_keyid (pk)) != 0
      /* We need the key block to find all user ids.  */
      || ! user_id_list)
    kb = get_pubkeyblock (pk->keyid);

  /* Make sure PK is a primary key.  */
  if (keyid_cmp (pk_keyid (pk), pk_main_keyid (pk)) != 0)
    pk = kb->pkt->pkt.public_key;

  if (! user_id_list)
    {
      /* Use all non-revoked user ids.  Do use expired user ids.  */
      kbnode_t n = kb;

      while ((n = find_next_kbnode (n, PKT_USER_ID)))
        {
	  PKT_user_id *uid = n->pkt->pkt.user_id;

          if (uid->is_revoked)
            continue;

          add_to_strlist (&user_id_list, uid->name);
        }

      free_user_id_list = 1;

      if (! user_id_list)
        log_info (_("WARNING: Encrypting to %s, which has no"
                    "non-revoked user ids.\n"),
                  keystr (pk->keyid));
    }

  fingerprint = hexfingerprint (pk, NULL, 0);

  tofu_begin_batch_update (ctrl);
  tofu_resume_batch_transaction (ctrl);

  for (user_id = user_id_list; user_id; user_id = user_id->next)
    {
      char *email = email_from_user_id (user_id->d);

      /* Make sure the binding exists and that we recognize any
         conflicts.  */
      int tl = get_trust (ctrl, pk, fingerprint, email, user_id->d,
                          may_ask, now);
      if (tl == _tofu_GET_TRUST_ERROR)
        {
          /* An error.  */
          rc = gpg_error (GPG_ERR_GENERAL);
          xfree (email);
          goto die;
        }

      rc = gpgsql_stepx
        (dbs->db, &dbs->s.register_insert, NULL, NULL, &err,
         "insert into encryptions\n"
         " (binding, time)\n"
         " values\n"
         " ((select oid from bindings\n"
         "    where fingerprint = ? and email = ?),\n"
         "  ?);",
         GPGSQL_ARG_STRING, fingerprint, GPGSQL_ARG_STRING, email,
         GPGSQL_ARG_LONG_LONG, (long long) now,
         GPGSQL_ARG_END);
      if (rc)
        {
          log_error (_("error updating TOFU database: %s\n"), err);
          print_further_info ("insert encryption");
          sqlite3_free (err);
        }

      xfree (email);
    }

 die:
  tofu_end_batch_update (ctrl);

  if (kb)
    release_kbnode (kb);

  if (free_user_id_list)
    free_strlist (user_id_list);

  xfree (fingerprint);

  return rc;
}


/* Combine a trust level returned from the TOFU trust model with a
   trust level returned by the PGP trust model.  This is primarily of
   interest when the trust model is tofu+pgp (TM_TOFU_PGP).

   This function ors together the upper bits (the values not covered
   by TRUST_MASK, i.e., TRUST_FLAG_REVOKED, etc.).  */
int
tofu_wot_trust_combine (int tofu_base, int wot_base)
{
  int tofu = tofu_base & TRUST_MASK;
  int wot = wot_base & TRUST_MASK;
  int upper = (tofu_base & ~TRUST_MASK) | (wot_base & ~TRUST_MASK);

  log_assert (tofu == TRUST_UNKNOWN
              || tofu == TRUST_EXPIRED
              || tofu == TRUST_UNDEFINED
              || tofu == TRUST_NEVER
              || tofu == TRUST_MARGINAL
              || tofu == TRUST_FULLY
              || tofu == TRUST_ULTIMATE);
  log_assert (wot == TRUST_UNKNOWN
              || wot == TRUST_EXPIRED
              || wot == TRUST_UNDEFINED
              || wot == TRUST_NEVER
              || wot == TRUST_MARGINAL
              || wot == TRUST_FULLY
              || wot == TRUST_ULTIMATE);

  /* We first consider negative trust policys.  These trump positive
     trust policies.  */
  if (tofu == TRUST_NEVER || wot == TRUST_NEVER)
    /* TRUST_NEVER trumps everything else.  */
    return upper | TRUST_NEVER;
  if (tofu == TRUST_EXPIRED || wot == TRUST_EXPIRED)
    /* TRUST_EXPIRED trumps everything but TRUST_NEVER.  */
    return upper | TRUST_EXPIRED;

  /* Now we only have positive or neutral trust policies.  We take
     the max.  */
  if (tofu == TRUST_ULTIMATE)
    return upper | TRUST_ULTIMATE | TRUST_FLAG_TOFU_BASED;
  if (wot == TRUST_ULTIMATE)
    return upper | TRUST_ULTIMATE;

  if (tofu == TRUST_FULLY)
    return upper | TRUST_FULLY | TRUST_FLAG_TOFU_BASED;
  if (wot == TRUST_FULLY)
    return upper | TRUST_FULLY;

  if (tofu == TRUST_MARGINAL)
    return upper | TRUST_MARGINAL | TRUST_FLAG_TOFU_BASED;
  if (wot == TRUST_MARGINAL)
    return upper | TRUST_MARGINAL;

  if (tofu == TRUST_UNDEFINED)
    return upper | TRUST_UNDEFINED | TRUST_FLAG_TOFU_BASED;
  if (wot == TRUST_UNDEFINED)
    return upper | TRUST_UNDEFINED;

  return upper | TRUST_UNKNOWN;
}


/* Write a "tfs" record for a --with-colons listing.  */
gpg_error_t
tofu_write_tfs_record (ctrl_t ctrl, estream_t fp,
                       PKT_public_key *pk, const char *user_id)
{
  time_t now = gnupg_get_time ();
  gpg_error_t err;
  tofu_dbs_t dbs;
  char *fingerprint;
  char *email;

  if (!*user_id)
    return 0;  /* No TOFU stats possible for an empty ID.  */

  dbs = opendbs (ctrl);
  if (!dbs)
    {
      err = gpg_error (GPG_ERR_GENERAL);
      log_error (_("error opening TOFU database: %s\n"), gpg_strerror (err));
      return err;
    }

  fingerprint = hexfingerprint (pk, NULL, 0);
  email = email_from_user_id (user_id);

  show_statistics (dbs, fingerprint, email, user_id, fp, now);

  xfree (email);
  xfree (fingerprint);
  return 0;
}


/* Return the validity (TRUST_NEVER, etc.) of the bindings
   <FINGERPRINT, USER_ID>, for each USER_ID in USER_ID_LIST.  If
   USER_ID_LIST->FLAG is set, then the id is considered to be expired.

   PK is the primary key packet.

   If MAY_ASK is 1 and the policy is TOFU_POLICY_ASK, then the user
   will be prompted to choose a policy.  If MAY_ASK is 0 and the
   policy is TOFU_POLICY_ASK, then TRUST_UNKNOWN is returned.

   Returns TRUST_UNDEFINED if an error occurs.  */
int
tofu_get_validity (ctrl_t ctrl, PKT_public_key *pk, strlist_t user_id_list,
		   int may_ask)
{
  time_t now = gnupg_get_time ();
  tofu_dbs_t dbs;
  char *fingerprint = NULL;
  strlist_t user_id;
  int trust_level = TRUST_UNKNOWN;
  int bindings = 0;
  int bindings_valid = 0;
  int need_warning = 0;

  dbs = opendbs (ctrl);
  if (! dbs)
    {
      log_error (_("error opening TOFU database: %s\n"),
                 gpg_strerror (GPG_ERR_GENERAL));
      return TRUST_UNDEFINED;
    }

  fingerprint = hexfingerprint (pk, NULL, 0);

  tofu_begin_batch_update (ctrl);
  /* Start the batch transaction now.  */
  tofu_resume_batch_transaction (ctrl);

  for (user_id = user_id_list; user_id; user_id = user_id->next, bindings ++)
    {
      char *email = email_from_user_id (user_id->d);

      /* Always call get_trust to make sure the binding is
         registered.  */
      int tl = get_trust (ctrl, pk, fingerprint, email, user_id->d,
                          may_ask, now);
      if (tl == _tofu_GET_TRUST_ERROR)
        {
          /* An error.  */
          trust_level = TRUST_UNDEFINED;
          xfree (email);
          goto die;
        }

      if (DBG_TRUST)
	log_debug ("TOFU: validity for <key: %s, user id: %s>: %s%s.\n",
		   fingerprint, email,
                   trust_value_to_string (tl),
                   user_id->flags ? " (but expired)" : "");

      if (user_id->flags)
        tl = TRUST_EXPIRED;

      if (tl != TRUST_EXPIRED)
        bindings_valid ++;

      if (may_ask && tl != TRUST_ULTIMATE && tl != TRUST_EXPIRED)
        need_warning |=
          show_statistics (dbs, fingerprint, email, user_id->d, NULL, now);

      if (tl == TRUST_NEVER)
        trust_level = TRUST_NEVER;
      else if (tl == TRUST_EXPIRED)
        /* Ignore expired bindings in the trust calculation.  */
        ;
      else if (tl > trust_level)
        {
          /* The expected values: */
          log_assert (tl == TRUST_UNKNOWN || tl == TRUST_UNDEFINED
                      || tl == TRUST_MARGINAL || tl == TRUST_FULLY
                      || tl == TRUST_ULTIMATE);

          /* We assume the following ordering:  */
          log_assert (TRUST_UNKNOWN < TRUST_UNDEFINED);
          log_assert (TRUST_UNDEFINED < TRUST_MARGINAL);
          log_assert (TRUST_MARGINAL < TRUST_FULLY);
          log_assert (TRUST_FULLY < TRUST_ULTIMATE);

          trust_level = tl;
        }

      xfree (email);
    }

  if (need_warning)
    show_warning (fingerprint, user_id_list);

 die:
  tofu_end_batch_update (ctrl);

  xfree (fingerprint);

  if (bindings_valid == 0)
    {
      if (DBG_TRUST)
        log_debug ("no (of %d) valid bindings."
                   "  Can't get TOFU validity for this set of user ids.\n",
                   bindings);
      return TRUST_NEVER;
    }

  return trust_level;
}

/* Set the policy for all non-revoked user ids in the keyblock KB to
   POLICY.

   If no key is available with the specified key id, then this
   function returns GPG_ERR_NO_PUBKEY.

   Returns 0 on success and an error code otherwise.  */
gpg_error_t
tofu_set_policy (ctrl_t ctrl, kbnode_t kb, enum tofu_policy policy)
{
  gpg_error_t err;
  time_t now = gnupg_get_time ();
  tofu_dbs_t dbs;
  PKT_public_key *pk;
  char *fingerprint = NULL;

  log_assert (kb->pkt->pkttype == PKT_PUBLIC_KEY);
  pk = kb->pkt->pkt.public_key;

  dbs = opendbs (ctrl);
  if (! dbs)
    {
      log_error (_("error opening TOFU database: %s\n"),
                 gpg_strerror (GPG_ERR_GENERAL));
      return gpg_error (GPG_ERR_GENERAL);
    }

  if (DBG_TRUST)
    log_debug ("Setting TOFU policy for %s to %s\n",
	       keystr (pk->keyid), tofu_policy_str (policy));
  if (keyid_cmp (pk_main_keyid (pk), pk_keyid (pk)) != 0)
    log_bug ("%s: Passed a subkey, but expecting a primary key.\n", __func__);

  fingerprint = hexfingerprint (pk, NULL, 0);

  begin_transaction (ctrl, 0);

  for (; kb; kb = kb->next)
    {
      PKT_user_id *user_id;
      char *email;

      if (kb->pkt->pkttype != PKT_USER_ID)
	continue;

      user_id = kb->pkt->pkt.user_id;
      if (user_id->is_revoked)
	/* Skip revoked user ids.  (Don't skip expired user ids, the
	   expiry can be changed.)  */
	continue;

      email = email_from_user_id (user_id->name);

      err = record_binding (dbs, fingerprint, email, user_id->name,
                            policy, 1, now);
      if (err)
        {
          log_error (_("error setting policy for key %s, user id \"%s\": %s"),
                     fingerprint, email, gpg_strerror (err));
          xfree (email);
          break;
        }

      xfree (email);
    }

  if (err)
    rollback_transaction (ctrl);
  else
    end_transaction (ctrl, 0);

  xfree (fingerprint);
  return err;
}

/* Set the TOFU policy for all non-revoked user ids in the KEY with
   the key id KEYID to POLICY.

   If no key is available with the specified key id, then this
   function returns GPG_ERR_NO_PUBKEY.

   Returns 0 on success and an error code otherwise.  */
gpg_error_t
tofu_set_policy_by_keyid (ctrl_t ctrl, u32 *keyid, enum tofu_policy policy)
{
  kbnode_t keyblock = get_pubkeyblock (keyid);
  if (! keyblock)
    return gpg_error (GPG_ERR_NO_PUBKEY);

  return tofu_set_policy (ctrl, keyblock, policy);
}

/* Return the TOFU policy for the specified binding in *POLICY.  If no
   policy has been set for the binding, sets *POLICY to
   TOFU_POLICY_NONE.

   PK is a primary public key and USER_ID is a user id.

   Returns 0 on success and an error code otherwise.  */
gpg_error_t
tofu_get_policy (ctrl_t ctrl, PKT_public_key *pk, PKT_user_id *user_id,
		 enum tofu_policy *policy)
{
  tofu_dbs_t dbs;
  char *fingerprint;
  char *email;

  /* Make sure PK is a primary key.  */
  log_assert (pk->main_keyid[0] == pk->keyid[0]
              && pk->main_keyid[1] == pk->keyid[1]);

  dbs = opendbs (ctrl);
  if (! dbs)
    {
      log_error (_("error opening TOFU database: %s\n"),
                 gpg_strerror (GPG_ERR_GENERAL));
      return gpg_error (GPG_ERR_GENERAL);
    }

  fingerprint = hexfingerprint (pk, NULL, 0);

  email = email_from_user_id (user_id->name);

  *policy = get_policy (dbs, fingerprint, email, NULL);

  xfree (email);
  xfree (fingerprint);
  if (*policy == _tofu_GET_POLICY_ERROR)
    return gpg_error (GPG_ERR_GENERAL);
  return 0;
}