/* ks-engine-hkp.c - HKP keyserver engine
 * Copyright (C) 2011 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

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

#include "dirmngr.h"
#include "misc.h"
#include "userids.h"
#include "ks-engine.h"

/* To match the behaviour of our old gpgkeys helper code we escape
   more characters than actually needed. */
#define EXTRA_ESCAPE_CHARS "@!\"#$%&'()*+,-./:;<=>?[\\]^_{|}~"

/* How many redirections do we allow.  */
#define MAX_REDIRECTS 2


/* Send an HTTP request.  On success returns an estream object at
   R_FP.  HOSTPORTSTR is only used for diagnostics. */
static gpg_error_t
send_request (ctrl_t ctrl, const char *request, const char *hostportstr,
              estream_t *r_fp)
{
  gpg_error_t err;
  http_t http = NULL;
  int redirects_left = MAX_REDIRECTS;
  estream_t fp = NULL;
  char *request_buffer = NULL;

  *r_fp = NULL;
 once_more:
  err = http_open (&http, HTTP_REQ_GET, request,
                   /* fixme: AUTH */ NULL,
                   0,
                   /* fixme: proxy*/ NULL,
                   NULL, NULL,
                   /*FIXME curl->srvtag*/NULL);
  if (!err)
    {
      fp = http_get_write_ptr (http);
      /* Avoid caches to get the most recent copy of the key.  We set
         both the Pragma and Cache-Control versions of the header, so
         we're good with both HTTP 1.0 and 1.1.  */
      es_fputs ("Pragma: no-cache\r\n"
                "Cache-Control: no-cache\r\n", fp);
      http_start_data (http);
      if (es_ferror (fp))
        err = gpg_error_from_syserror ();
    }
  if (err)
    {
      /* Fixme: After a redirection we show the old host name.  */
      log_error (_("error connecting to `%s': %s\n"),
                 hostportstr, gpg_strerror (err));
      goto leave;
    }

  /* Wait for the response.  */
  dirmngr_tick (ctrl);
  err = http_wait_response (http);
  if (err)
    {
      log_error (_("error reading HTTP response for `%s': %s\n"),
                 hostportstr, gpg_strerror (err));
      goto leave;
    }

  switch (http_get_status_code (http))
    {
    case 200:
      err = 0;
      break; /* Success.  */

    case 301:
    case 302:
      {
        const char *s = http_get_header (http, "Location");
        
        log_info (_("URL `%s' redirected to `%s' (%u)\n"),
                  request, s?s:"[none]", http_get_status_code (http));
        if (s && *s && redirects_left-- )
          {
            xfree (request_buffer);
            request_buffer = xtrystrdup (s);
            if (request_buffer)
              {
                request = request_buffer;
                http_close (http, 0);
                http = NULL;
                goto once_more;
              }
            err = gpg_error_from_syserror ();
          }
        else
          err = gpg_error (GPG_ERR_NO_DATA);
        log_error (_("too many redirections\n"));
      }
      goto leave;

    default:
      log_error (_("error accessing `%s': http status %u\n"),
                 request, http_get_status_code (http));
      err = gpg_error (GPG_ERR_NO_DATA);
      goto leave;
    }

  fp = http_get_read_ptr (http);
  if (!fp)
    {
      err = gpg_error (GPG_ERR_BUG);
      goto leave;
    }

  /* Return the read stream and close the HTTP context.  */
  *r_fp = fp;
  fp = NULL;
  http_close (http, 1);
  http = NULL;

 leave:
  es_fclose (fp);
  http_close (http, 0);
  xfree (request_buffer);
  return err;
}



/* Search the keyserver identified by URI for keys matching PATTERN.
   On success R_FP has an open stream to read the data.  */
gpg_error_t
ks_hkp_search (ctrl_t ctrl, parsed_uri_t uri, const char *pattern,
               estream_t *r_fp)
{
  gpg_error_t err;
  KEYDB_SEARCH_DESC desc;
  char fprbuf[2+40+1];
  const char *scheme;
  char portstr[10];
  char *hostport = NULL;
  char *request = NULL;
  estream_t fp = NULL;

  *r_fp = NULL;

  /* Remove search type indicator and adjust PATTERN accordingly.
     Note that HKP keyservers like the 0x to be present when searching
     by keyid.  We need to re-format the fingerprint and keyids so to
     remove the gpg specific force-use-of-this-key flag ("!").  */
  err = classify_user_id (pattern, &desc);
  if (err)
    return err;
  switch (desc.mode)
    {
    case KEYDB_SEARCH_MODE_EXACT:
    case KEYDB_SEARCH_MODE_SUBSTR:
    case KEYDB_SEARCH_MODE_MAIL:
    case KEYDB_SEARCH_MODE_MAILSUB:
      pattern = desc.u.name;
      break;
    case KEYDB_SEARCH_MODE_SHORT_KID:
      snprintf (fprbuf, sizeof fprbuf, "0x%08lX", (ulong)desc.u.kid[1]);
      pattern = fprbuf;
      break;
    case KEYDB_SEARCH_MODE_LONG_KID:
      snprintf (fprbuf, sizeof fprbuf, "0x%08lX%08lX", 
                (ulong)desc.u.kid[0], (ulong)desc.u.kid[1]);
      pattern = fprbuf;
      break;
    case KEYDB_SEARCH_MODE_FPR16:
      bin2hex (desc.u.fpr, 16, fprbuf);
      pattern = fprbuf;
      break;
    case KEYDB_SEARCH_MODE_FPR20:
    case KEYDB_SEARCH_MODE_FPR:
      bin2hex (desc.u.fpr, 20, fprbuf);
      pattern = fprbuf;
      break;
    default:
      return gpg_error (GPG_ERR_INV_USER_ID);
    }
  
  /* Map scheme and port.  */
  if (!strcmp (uri->scheme,"hkps") || !strcmp (uri->scheme,"https"))
    {
      scheme = "https";
      strcpy (portstr, "443");
    }
  else /* HKP or HTTP.  */
    {
      scheme = "http";
      strcpy (portstr, "11371");
    }
  if (uri->port)
    snprintf (portstr, sizeof portstr, "%hu", uri->port);
  else
    {} /*fixme_do_srv_lookup ()*/

  /* Build the request string.  */
  {
    char *searchkey;

    hostport = strconcat (scheme, "://", 
                          *uri->host? uri->host: "localhost",
                          ":", portstr, NULL);
    if (!hostport)
      {
        err = gpg_error_from_syserror ();
        goto leave;
      }

    searchkey = http_escape_string (pattern, EXTRA_ESCAPE_CHARS);
    if (!searchkey)
      {
        err = gpg_error_from_syserror ();
        goto leave;
      }

    request = strconcat (hostport,
                         "/pks/lookup?op=index&options=mr&search=",
                         searchkey,
                         NULL);
    xfree (searchkey);
    if (!request)
      {
        err = gpg_error_from_syserror ();
        goto leave;
      }
  }
  
  /* Send the request.  */
  err = send_request (ctrl, request, hostport, &fp);
  if (err)
    goto leave;

  /* Start reading the response.  */
  {
    int c = es_getc (fp);
    if (c == -1)
      {
        err = es_ferror (fp)?gpg_error_from_syserror ():gpg_error (GPG_ERR_EOF);
        log_error ("error reading response: %s\n", gpg_strerror (err));
        goto leave;
      }
    if (c == '<')
      {
        /* The document begins with a '<', assume it's a HTML
           response, which we don't support.  */
        err = gpg_error (GPG_ERR_UNSUPPORTED_ENCODING);
        goto leave;
      }
    es_ungetc (c, fp);
  }

  /* Return the read stream.  */
  *r_fp = fp;
  fp = NULL;

 leave:
  es_fclose (fp);
  xfree (request);
  xfree (hostport);
  return err;
}


/* Get the key described key the KEYSPEC string from the keyserver
   identified by URI.  On success R_FP has an open stream to read the
   data.  */
gpg_error_t
ks_hkp_get (ctrl_t ctrl, parsed_uri_t uri, const char *keyspec, estream_t *r_fp)
{
  gpg_error_t err;
  KEYDB_SEARCH_DESC desc;
  char kidbuf[8+1];
  const char *scheme;
  char portstr[10];
  char *hostport = NULL;
  char *request = NULL;
  estream_t fp = NULL;

  *r_fp = NULL;

  /* Remove search type indicator and adjust PATTERN accordingly.
     Note that HKP keyservers like the 0x to be present when searching
     by keyid.  We need to re-format the fingerprint and keyids so to
     remove the gpg specific force-use-of-this-key flag ("!").  */
  err = classify_user_id (keyspec, &desc);
  if (err)
    return err;
  switch (desc.mode)
    {
    case KEYDB_SEARCH_MODE_SHORT_KID:
    case KEYDB_SEARCH_MODE_LONG_KID:
      snprintf (kidbuf, sizeof kidbuf, "%08lX", (ulong)desc.u.kid[1]);
      break;
    case KEYDB_SEARCH_MODE_FPR20:
    case KEYDB_SEARCH_MODE_FPR:
      /* This is a v4 fingerprint.  Take the last 8 hex digits from
         the fingerprint which is the expected short keyid.  */
      bin2hex (desc.u.fpr+16, 4, kidbuf);
      break;

    case KEYDB_SEARCH_MODE_FPR16:
      log_error ("HKP keyserver do not support v3 fingerprints\n");
    default:
      return gpg_error (GPG_ERR_INV_USER_ID);
    }
  
  /* Map scheme and port.  */
  if (!strcmp (uri->scheme,"hkps") || !strcmp (uri->scheme,"https"))
    {
      scheme = "https";
      strcpy (portstr, "443");
    }
  else /* HKP or HTTP.  */
    {
      scheme = "http";
      strcpy (portstr, "11371");
    }
  if (uri->port)
    snprintf (portstr, sizeof portstr, "%hu", uri->port);
  else
    {} /*fixme_do_srv_lookup ()*/

  /* Build the request string.  */
  {
    hostport = strconcat (scheme, "://", 
                          *uri->host? uri->host: "localhost",
                          ":", portstr, NULL);
    if (!hostport)
      {
        err = gpg_error_from_syserror ();
        goto leave;
      }

    request = strconcat (hostport,
                         "/pks/lookup?op=get&options=mr&search=0x",
                         kidbuf,
                         NULL);
    if (!request)
      {
        err = gpg_error_from_syserror ();
        goto leave;
      }
  }
  
  /* Send the request.  */
  err = send_request (ctrl, request, hostport, &fp);
  if (err)
    goto leave;

  /* Return the read stream and close the HTTP context.  */
  *r_fp = fp;
  fp = NULL;

 leave:
  es_fclose (fp);
  xfree (request);
  xfree (hostport);
  return err;
}