/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */

/* GIO - GLib Input, Output and Streaming Library
 *
 * Copyright (C) 2008 Red Hat, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General
 * Public License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "config.h"
#include <glib.h>
#include "glibintl.h"

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

#include "gthreadedresolver.h"
#include "gnetworkingprivate.h"

#include "gcancellable.h"
#include "ginetaddress.h"
#include "ginetsocketaddress.h"
#include "gtask.h"
#include "gsocketaddress.h"
#include "gsrvtarget.h"


G_DEFINE_TYPE (GThreadedResolver, g_threaded_resolver, G_TYPE_RESOLVER)

static void
g_threaded_resolver_init (GThreadedResolver *gtr)
{
}

static GResolverError
g_resolver_error_from_addrinfo_error (gint err)
{
  switch (err)
    {
    case EAI_FAIL:
#if defined(EAI_NODATA) && (EAI_NODATA != EAI_NONAME)
    case EAI_NODATA:
#endif
    case EAI_NONAME:
      return G_RESOLVER_ERROR_NOT_FOUND;

    case EAI_AGAIN:
      return G_RESOLVER_ERROR_TEMPORARY_FAILURE;

    default:
      return G_RESOLVER_ERROR_INTERNAL;
    }
}

static struct addrinfo addrinfo_hints;

static void
do_lookup_by_name (GTask         *task,
                   gpointer       source_object,
                   gpointer       task_data,
                   GCancellable  *cancellable)
{
  const char *hostname = task_data;
  struct addrinfo *res = NULL;
  GList *addresses;
  gint retval;

  retval = getaddrinfo (hostname, NULL, &addrinfo_hints, &res);

  if (retval == 0)
    {
      struct addrinfo *ai;
      GSocketAddress *sockaddr;
      GInetAddress *addr;

      addresses = NULL;
      for (ai = res; ai; ai = ai->ai_next)
        {
          sockaddr = g_socket_address_new_from_native (ai->ai_addr, ai->ai_addrlen);
          if (!sockaddr || !G_IS_INET_SOCKET_ADDRESS (sockaddr))
            continue;

          addr = g_object_ref (g_inet_socket_address_get_address ((GInetSocketAddress *)sockaddr));
          addresses = g_list_prepend (addresses, addr);
          g_object_unref (sockaddr);
        }

      addresses = g_list_reverse (addresses);
      g_task_return_pointer (task, addresses,
                             (GDestroyNotify)g_resolver_free_addresses);
    }
  else
    {
      g_task_return_new_error (task,
                               G_RESOLVER_ERROR,
                               g_resolver_error_from_addrinfo_error (retval),
                               _("Error resolving '%s': %s"),
                               hostname, gai_strerror (retval));
    }

  if (res)
    freeaddrinfo (res);
}

static GList *
lookup_by_name (GResolver     *resolver,
                const gchar   *hostname,
                GCancellable  *cancellable,
                GError       **error)
{
  GTask *task;
  GList *addresses;

  task = g_task_new (resolver, cancellable, NULL, NULL);
  g_task_set_task_data (task, g_strdup (hostname), g_free);
  g_task_set_return_on_cancel (task, TRUE);
  g_task_run_in_thread_sync (task, do_lookup_by_name);
  addresses = g_task_propagate_pointer (task, error);
  g_object_unref (task);

  return addresses;
}

static void
lookup_by_name_async (GResolver           *resolver,
                      const gchar         *hostname,
                      GCancellable        *cancellable,
                      GAsyncReadyCallback  callback,
                      gpointer             user_data)
{
  GTask *task;

  task = g_task_new (resolver, cancellable, callback, user_data);
  g_task_set_task_data (task, g_strdup (hostname), g_free);
  g_task_set_return_on_cancel (task, TRUE);
  g_task_run_in_thread (task, do_lookup_by_name);
  g_object_unref (task);
}

static GList *
lookup_by_name_finish (GResolver     *resolver,
                       GAsyncResult  *result,
                       GError       **error)
{
  g_return_val_if_fail (g_task_is_valid (result, resolver), NULL);

  return g_task_propagate_pointer (G_TASK (result), error);
}


static void
do_lookup_by_address (GTask         *task,
                      gpointer       source_object,
                      gpointer       task_data,
                      GCancellable  *cancellable)
{
  GInetAddress *address = task_data;
  struct sockaddr_storage sockaddr;
  gsize sockaddr_size;
  GSocketAddress *gsockaddr;
  gchar name[NI_MAXHOST];
  gint retval;

  gsockaddr = g_inet_socket_address_new (address, 0);
  g_socket_address_to_native (gsockaddr, (struct sockaddr *)&sockaddr,
                              sizeof (sockaddr), NULL);
  sockaddr_size = g_socket_address_get_native_size (gsockaddr);
  g_object_unref (gsockaddr);

  retval = getnameinfo ((struct sockaddr *)&sockaddr, sockaddr_size,
                        name, sizeof (name), NULL, 0, NI_NAMEREQD);
  if (retval == 0)
    g_task_return_pointer (task, g_strdup (name), g_free);
  else
    {
      gchar *phys;

      phys = g_inet_address_to_string (address);
      g_task_return_new_error (task,
                               G_RESOLVER_ERROR,
                               g_resolver_error_from_addrinfo_error (retval),
                               _("Error reverse-resolving '%s': %s"),
                               phys ? phys : "(unknown)",
                               gai_strerror (retval));
      g_free (phys);
    }
}

static gchar *
lookup_by_address (GResolver        *resolver,
                   GInetAddress     *address,
                   GCancellable     *cancellable,
                   GError          **error)
{
  GTask *task;
  gchar *name;

  task = g_task_new (resolver, cancellable, NULL, NULL);
  g_task_set_task_data (task, g_object_ref (address), g_object_unref);
  g_task_set_return_on_cancel (task, TRUE);
  g_task_run_in_thread_sync (task, do_lookup_by_address);
  name = g_task_propagate_pointer (task, error);
  g_object_unref (task);

  return name;
}

static void
lookup_by_address_async (GResolver           *resolver,
                         GInetAddress        *address,
                         GCancellable        *cancellable,
                         GAsyncReadyCallback  callback,
                         gpointer             user_data)
{
  GTask *task;

  task = g_task_new (resolver, cancellable, callback, user_data);
  g_task_set_task_data (task, g_object_ref (address), g_object_unref);
  g_task_set_return_on_cancel (task, TRUE);
  g_task_run_in_thread (task, do_lookup_by_address);
  g_object_unref (task);
}

static gchar *
lookup_by_address_finish (GResolver     *resolver,
                          GAsyncResult  *result,
                          GError       **error)
{
  g_return_val_if_fail (g_task_is_valid (result, resolver), NULL);

  return g_task_propagate_pointer (G_TASK (result), error);
}


#if defined(G_OS_UNIX)
static GVariant *
parse_res_srv (guchar  *answer,
               guchar  *end,
               guchar **p)
{
  gchar namebuf[1024];
  guint16 priority, weight, port;

  GETSHORT (priority, *p);
  GETSHORT (weight, *p);
  GETSHORT (port, *p);
  *p += dn_expand (answer, end, *p, namebuf, sizeof (namebuf));

  return g_variant_new ("(qqqs)",
                        priority,
                        weight,
                        port,
                        namebuf);
}

static GVariant *
parse_res_soa (guchar  *answer,
               guchar  *end,
               guchar **p)
{
  gchar mnamebuf[1024];
  gchar rnamebuf[1024];
  guint32 serial, refresh, retry, expire, ttl;

  *p += dn_expand (answer, end, *p, mnamebuf, sizeof (mnamebuf));
  *p += dn_expand (answer, end, *p, rnamebuf, sizeof (rnamebuf));

  GETLONG (serial, *p);
  GETLONG (refresh, *p);
  GETLONG (retry, *p);
  GETLONG (expire, *p);
  GETLONG (ttl, *p);

  return g_variant_new ("(ssuuuuu)",
                        mnamebuf,
                        rnamebuf,
                        serial,
                        refresh,
                        retry,
                        expire,
                        ttl);
}

static GVariant *
parse_res_ns (guchar  *answer,
              guchar  *end,
              guchar **p)
{
  gchar namebuf[1024];

  *p += dn_expand (answer, end, *p, namebuf, sizeof (namebuf));

  return g_variant_new ("(s)", namebuf);
}

static GVariant *
parse_res_mx (guchar  *answer,
              guchar  *end,
              guchar **p)
{
  gchar namebuf[1024];
  guint16 preference;

  GETSHORT (preference, *p);

  *p += dn_expand (answer, end, *p, namebuf, sizeof (namebuf));

  return g_variant_new ("(qs)",
                        preference,
                        namebuf);
}

static GVariant *
parse_res_txt (guchar  *answer,
               guchar  *end,
               guchar **p)
{
  GVariant *record;
  GPtrArray *array;
  guchar *at = *p;
  gsize len;

  array = g_ptr_array_new_with_free_func (g_free);
  while (at < end)
    {
      len = *(at++);
      if (len > at - end)
        break;
      g_ptr_array_add (array, g_strndup ((gchar *)at, len));
      at += len;
    }

  *p = at;
  record = g_variant_new ("(@as)",
                          g_variant_new_strv ((const gchar **)array->pdata, array->len));
  g_ptr_array_free (array, TRUE);
  return record;
}

static gint
g_resolver_record_type_to_rrtype (GResolverRecordType type)
{
  switch (type)
  {
    case G_RESOLVER_RECORD_SRV:
      return T_SRV;
    case G_RESOLVER_RECORD_TXT:
      return T_TXT;
    case G_RESOLVER_RECORD_SOA:
      return T_SOA;
    case G_RESOLVER_RECORD_NS:
      return T_NS;
    case G_RESOLVER_RECORD_MX:
      return T_MX;
  }
  g_return_val_if_reached (-1);
}

static GList *
g_resolver_records_from_res_query (const gchar      *rrname,
                                   gint              rrtype,
                                   guchar           *answer,
                                   gint              len,
                                   gint              herr,
                                   GError          **error)
{
  gint count;
  gchar namebuf[1024];
  guchar *end, *p;
  guint16 type, qclass, rdlength;
  guint32 ttl;
  HEADER *header;
  GList *records;
  GVariant *record;

  if (len <= 0)
    {
      GResolverError errnum;
      const gchar *format;

      if (len == 0 || herr == HOST_NOT_FOUND || herr == NO_DATA)
        {
          errnum = G_RESOLVER_ERROR_NOT_FOUND;
          format = _("No DNS record of the requested type for '%s'");
        }
      else if (herr == TRY_AGAIN)
        {
          errnum = G_RESOLVER_ERROR_TEMPORARY_FAILURE;
          format = _("Temporarily unable to resolve '%s'");
        }
      else
        {
          errnum = G_RESOLVER_ERROR_INTERNAL;
          format = _("Error resolving '%s'");
        }

      g_set_error (error, G_RESOLVER_ERROR, errnum, format, rrname);
      return NULL;
    }

  records = NULL;

  header = (HEADER *)answer;
  p = answer + sizeof (HEADER);
  end = answer + len;

  /* Skip query */
  count = ntohs (header->qdcount);
  while (count-- && p < end)
    {
      p += dn_expand (answer, end, p, namebuf, sizeof (namebuf));
      p += 4;

      /* To silence gcc warnings */
      namebuf[0] = namebuf[1];
    }

  /* Read answers */
  count = ntohs (header->ancount);
  while (count-- && p < end)
    {
      p += dn_expand (answer, end, p, namebuf, sizeof (namebuf));
      GETSHORT (type, p);
      GETSHORT (qclass, p);
      GETLONG  (ttl, p);
      ttl = ttl; /* To avoid -Wunused-but-set-variable */
      GETSHORT (rdlength, p);

      if (type != rrtype || qclass != C_IN)
        {
          p += rdlength;
          continue;
        }

      switch (rrtype)
        {
        case T_SRV:
          record = parse_res_srv (answer, end, &p);
          break;
        case T_MX:
          record = parse_res_mx (answer, end, &p);
          break;
        case T_SOA:
          record = parse_res_soa (answer, end, &p);
          break;
        case T_NS:
          record = parse_res_ns (answer, end, &p);
          break;
        case T_TXT:
          record = parse_res_txt (answer, p + rdlength, &p);
          break;
        default:
          g_warn_if_reached ();
          record = NULL;
          break;
        }

      if (record != NULL)
        records = g_list_prepend (records, record);
    }

    return records;
}

#elif defined(G_OS_WIN32)

static GVariant *
parse_dns_srv (DNS_RECORD *rec)
{
  return g_variant_new ("(qqqs)",
                        (guint16)rec->Data.SRV.wPriority,
                        (guint16)rec->Data.SRV.wWeight,
                        (guint16)rec->Data.SRV.wPort,
                        rec->Data.SRV.pNameTarget);
}

static GVariant *
parse_dns_soa (DNS_RECORD *rec)
{
  return g_variant_new ("(ssuuuuu)",
                        rec->Data.SOA.pNamePrimaryServer,
                        rec->Data.SOA.pNameAdministrator,
                        (guint32)rec->Data.SOA.dwSerialNo,
                        (guint32)rec->Data.SOA.dwRefresh,
                        (guint32)rec->Data.SOA.dwRetry,
                        (guint32)rec->Data.SOA.dwExpire,
                        (guint32)rec->Data.SOA.dwDefaultTtl);
}

static GVariant *
parse_dns_ns (DNS_RECORD *rec)
{
  return g_variant_new ("(s)", rec->Data.NS.pNameHost);
}

static GVariant *
parse_dns_mx (DNS_RECORD *rec)
{
  return g_variant_new ("(qs)",
                        (guint16)rec->Data.MX.wPreference,
                        rec->Data.MX.pNameExchange);
}

static GVariant *
parse_dns_txt (DNS_RECORD *rec)
{
  GVariant *record;
  GPtrArray *array;
  DWORD i;

  array = g_ptr_array_new ();
  for (i = 0; i < rec->Data.TXT.dwStringCount; i++)
    g_ptr_array_add (array, rec->Data.TXT.pStringArray[i]);
  record = g_variant_new ("(@as)",
                          g_variant_new_strv ((const gchar **)array->pdata, array->len));
  g_ptr_array_free (array, TRUE);
  return record;
}

static WORD
g_resolver_record_type_to_dnstype (GResolverRecordType type)
{
  switch (type)
  {
    case G_RESOLVER_RECORD_SRV:
      return DNS_TYPE_SRV;
    case G_RESOLVER_RECORD_TXT:
      return DNS_TYPE_TEXT;
    case G_RESOLVER_RECORD_SOA:
      return DNS_TYPE_SOA;
    case G_RESOLVER_RECORD_NS:
      return DNS_TYPE_NS;
    case G_RESOLVER_RECORD_MX:
      return DNS_TYPE_MX;
  }
  g_return_val_if_reached (-1);
}

static GList *
g_resolver_records_from_DnsQuery (const gchar  *rrname,
                                  WORD          dnstype,
                                  DNS_STATUS    status,
                                  DNS_RECORD   *results,
                                  GError      **error)
{
  DNS_RECORD *rec;
  gpointer record;
  GList *records;

  if (status != ERROR_SUCCESS)
    {
      GResolverError errnum;
      const gchar *format;

      if (status == DNS_ERROR_RCODE_NAME_ERROR)
        {
          errnum = G_RESOLVER_ERROR_NOT_FOUND;
          format = _("No DNS record of the requested type for '%s'");
        }
      else if (status == DNS_ERROR_RCODE_SERVER_FAILURE)
        {
          errnum = G_RESOLVER_ERROR_TEMPORARY_FAILURE;
          format = _("Temporarily unable to resolve '%s'");
        }
      else
        {
          errnum = G_RESOLVER_ERROR_INTERNAL;
          format = _("Error resolving '%s'");
        }

      g_set_error (error, G_RESOLVER_ERROR, errnum, format, rrname);
      return NULL;
    }

  records = NULL;
  for (rec = results; rec; rec = rec->pNext)
    {
      if (rec->wType != dnstype)
        continue;
      switch (dnstype)
        {
        case DNS_TYPE_SRV:
          record = parse_dns_srv (rec);
          break;
        case DNS_TYPE_SOA:
          record = parse_dns_soa (rec);
          break;
        case DNS_TYPE_NS:
          record = parse_dns_ns (rec);
          break;
        case DNS_TYPE_MX:
          record = parse_dns_mx (rec);
          break;
        case DNS_TYPE_TEXT:
          record = parse_dns_txt (rec);
          break;
        default:
          g_warn_if_reached ();
          record = NULL;
          break;
        }
      if (record != NULL)
        records = g_list_prepend (records, g_variant_ref_sink (record));
    }

  return records;
}

#endif

typedef struct {
  char *rrname;
  GResolverRecordType record_type;
} LookupRecordsData;

static void
free_lookup_records_data (LookupRecordsData *lrd)
{
  g_free (lrd->rrname);
  g_slice_free (LookupRecordsData, lrd);
}

static void
free_records (GList *records)
{
  g_list_free_full (records, (GDestroyNotify) g_variant_unref);
}

static void
do_lookup_records (GTask         *task,
                   gpointer       source_object,
                   gpointer       task_data,
                   GCancellable  *cancellable)
{
  LookupRecordsData *lrd = task_data;
  GList *records;
  GError *error = NULL;

#if defined(G_OS_UNIX)
  gint len = 512;
  gint herr;
  GByteArray *answer;
  gint rrtype;

  rrtype = g_resolver_record_type_to_rrtype (lrd->record_type);
  answer = g_byte_array_new ();
  for (;;)
    {
      g_byte_array_set_size (answer, len * 2);
      len = res_query (lrd->rrname, C_IN, rrtype, answer->data, answer->len);

      /* If answer fit in the buffer then we're done */
      if (len < 0 || len < (gint)answer->len)
        break;

      /*
       * On overflow some res_query's return the length needed, others
       * return the full length entered. This code works in either case.
       */
    }

  herr = h_errno;
  records = g_resolver_records_from_res_query (lrd->rrname, rrtype, answer->data, len, herr, &error);
  g_byte_array_free (answer, TRUE);

#else

  DNS_STATUS status;
  DNS_RECORD *results = NULL;
  WORD dnstype;

  dnstype = g_resolver_record_type_to_dnstype (lrd->record_type);
  status = DnsQuery_A (lrd->rrname, dnstype, DNS_QUERY_STANDARD, NULL, &results, NULL);
  records = g_resolver_records_from_DnsQuery (lrd->rrname, dnstype, status, results, &error);
  if (results != NULL)
    DnsRecordListFree (results, DnsFreeRecordList);

#endif

  if (records)
    g_task_return_pointer (task, records, (GDestroyNotify) free_records);
  else
    g_task_return_error (task, error);
}

static GList *
lookup_records (GResolver              *resolver,
                const gchar            *rrname,
                GResolverRecordType     record_type,
                GCancellable           *cancellable,
                GError                **error)
{
  GTask *task;
  GList *records;
  LookupRecordsData *lrd;

  task = g_task_new (resolver, cancellable, NULL, NULL);

  lrd = g_slice_new (LookupRecordsData);
  lrd->rrname = g_strdup (rrname);
  lrd->record_type = record_type;
  g_task_set_task_data (task, lrd, (GDestroyNotify) free_lookup_records_data);

  g_task_set_return_on_cancel (task, TRUE);
  g_task_run_in_thread_sync (task, do_lookup_records);
  records = g_task_propagate_pointer (task, error);
  g_object_unref (task);

  return records;
}

static void
lookup_records_async (GResolver           *resolver,
                      const char          *rrname,
                      GResolverRecordType  record_type,
                      GCancellable        *cancellable,
                      GAsyncReadyCallback  callback,
                      gpointer             user_data)
{
  GTask *task;
  LookupRecordsData *lrd;

  task = g_task_new (resolver, cancellable, callback, user_data);

  lrd = g_slice_new (LookupRecordsData);
  lrd->rrname = g_strdup (rrname);
  lrd->record_type = record_type;
  g_task_set_task_data (task, lrd, (GDestroyNotify) free_lookup_records_data);

  g_task_set_return_on_cancel (task, TRUE);
  g_task_run_in_thread (task, do_lookup_records);
  g_object_unref (task);
}

static GList *
lookup_records_finish (GResolver     *resolver,
                       GAsyncResult  *result,
                       GError       **error)
{
  g_return_val_if_fail (g_task_is_valid (result, resolver), NULL);

  return g_task_propagate_pointer (G_TASK (result), error);
}


static void
g_threaded_resolver_class_init (GThreadedResolverClass *threaded_class)
{
  GResolverClass *resolver_class = G_RESOLVER_CLASS (threaded_class);

  resolver_class->lookup_by_name           = lookup_by_name;
  resolver_class->lookup_by_name_async     = lookup_by_name_async;
  resolver_class->lookup_by_name_finish    = lookup_by_name_finish;
  resolver_class->lookup_by_address        = lookup_by_address;
  resolver_class->lookup_by_address_async  = lookup_by_address_async;
  resolver_class->lookup_by_address_finish = lookup_by_address_finish;
  resolver_class->lookup_records           = lookup_records;
  resolver_class->lookup_records_async     = lookup_records_async;
  resolver_class->lookup_records_finish    = lookup_records_finish;

  /* Initialize _g_resolver_addrinfo_hints */
#ifdef AI_ADDRCONFIG
  addrinfo_hints.ai_flags |= AI_ADDRCONFIG;
#endif
  /* These two don't actually matter, they just get copied into the
   * returned addrinfo structures (and then we ignore them). But if
   * we leave them unset, we'll get back duplicate answers.
   */
  addrinfo_hints.ai_socktype = SOCK_STREAM;
  addrinfo_hints.ai_protocol = IPPROTO_TCP;
}