Adding upstream version 2.2.40.upstream/2.2.40

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2478 insertions, 0 deletions

diff --git a/dirmngr/dns-stuff.c b/dirmngr/dns-stuff.c
new file mode 100644
index 0000000..4a50d75
--- /dev/null
+++ b/dirmngr/dns-stuff.c
@@ -0,0 +1,2478 @@
+/* dns-stuff.c - DNS related code including CERT RR (rfc-4398)
+ * Copyright (C) 2003, 2005, 2006, 2009 Free Software Foundation, Inc.
+ * Copyright (C) 2005, 2006, 2009, 2015. 2016 Werner Koch
+ *
+ * This file is part of GnuPG.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either
+ *
+ *   - the GNU Lesser General Public License as published by the Free
+ *     Software Foundation; either version 3 of the License, or (at
+ *     your option) any later version.
+ *
+ * or
+ *
+ *   - the GNU General Public License as published by the Free
+ *     Software Foundation; either version 2 of the License, or (at
+ *     your option) any later version.
+ *
+ * or both in parallel, as here.
+ *
+ * This file 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 <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <sys/types.h>
+#ifdef HAVE_W32_SYSTEM
+# define WIN32_LEAN_AND_MEAN
+# ifdef HAVE_WINSOCK2_H
+#  include <winsock2.h>
+# endif
+# include <windows.h>
+# include <iphlpapi.h>
+#else
+# if HAVE_SYSTEM_RESOLVER
+#  include <netinet/in.h>
+#  include <arpa/nameser.h>
+#  include <resolv.h>
+# endif
+# include <netdb.h>
+#endif
+#ifdef HAVE_STAT
+# include <sys/stat.h>
+#endif
+#include <string.h>
+#include <unistd.h>
+
+
+/* William Ahern's DNS library, included as a source copy.  */
+#ifdef USE_LIBDNS
+# include "dns.h"
+#endif
+
+/* dns.c has a dns_p_free but it is not exported.  We use our own
+ * wrapper here so that we do not accidentally use xfree which would
+ * be wrong for dns.c allocated data.  */
+#define dns_free(a)  free ((a))
+
+
+#ifdef WITHOUT_NPTH /* Give the Makefile a chance to build without Pth.  */
+# undef USE_NPTH
+#endif
+#ifdef USE_NPTH
+# include <npth.h>
+#endif
+
+#include "./dirmngr-err.h"
+#include "../common/util.h"
+#include "../common/host2net.h"
+#include "dns-stuff.h"
+
+#ifdef USE_NPTH
+# define my_unprotect()        npth_unprotect ()
+# define my_protect()          npth_protect ()
+#else
+# define my_unprotect()        do { } while(0)
+# define my_protect()          do { } while(0)
+#endif
+
+/* We allow the use of 0 instead of AF_UNSPEC - check this assumption.  */
+#if AF_UNSPEC != 0
+# error AF_UNSPEC does not have the value 0
+#endif
+
+/* Windows does not support the AI_ADDRCONFIG flag - use zero instead.  */
+#ifndef AI_ADDRCONFIG
+# define AI_ADDRCONFIG 0
+#endif
+
+/* Not every installation has gotten around to supporting SRVs or
+   CERTs yet... */
+#ifndef T_SRV
+#define T_SRV 33
+#endif
+#undef T_CERT
+#define T_CERT 37
+
+/* The standard SOCKS and TOR ports.  */
+#define SOCKS_PORT 1080
+#define TOR_PORT   9050
+#define TOR_PORT2  9150   /* (Used by the Tor browser) */
+
+
+/* The default nameserver used in Tor mode.  */
+#define DEFAULT_NAMESERVER "8.8.8.8"
+
+/* The default timeout in seconds for libdns requests.  */
+#define DEFAULT_TIMEOUT 30
+
+
+#define RESOLV_CONF_NAME "/etc/resolv.conf"
+
+/* Two flags to enable verbose and debug mode.  */
+static int opt_verbose;
+static int opt_debug;
+
+/* The timeout in seconds for libdns requests.  */
+static int opt_timeout;
+
+/* The flag to disable IPv4 access - right now this only skips
+ * returned A records.  */
+static int opt_disable_ipv4;
+
+/* The flag to disable IPv6 access - right now this only skips
+ * returned AAAA records.  */
+static int opt_disable_ipv6;
+
+/* If set force the use of the standard resolver.  */
+static int standard_resolver;
+
+/* If set use recursive resolver when available. */
+static int recursive_resolver;
+
+/* If set Tor mode shall be used.  */
+static int tor_mode;
+
+/* A string with the nameserver IP address used with Tor.
+  (40 should be sufficient for v6 but we add some extra for a scope.) */
+static char tor_nameserver[40+20];
+
+/* Two strings to hold the credentials presented to Tor.  */
+static char tor_socks_user[30];
+static char tor_socks_password[20];
+
+/* To avoid checking the interface too often we cache the result.  */
+static struct
+{
+  unsigned int valid:1;
+  unsigned int v4:1;
+  unsigned int v6:1;
+} cached_inet_support;
+
+
+
+#ifdef USE_LIBDNS
+/* Libdns gobal data.  */
+struct libdns_s
+{
+  struct dns_resolv_conf *resolv_conf;
+  struct dns_hosts *hosts;
+  struct dns_hints *hints;
+
+  struct sockaddr_storage socks_host;
+} libdns;
+
+/* If this flag is set, libdns shall be reinited for the next use.  */
+static int libdns_reinit_pending;
+
+/* The Tor port to be used.  */
+static int libdns_tor_port;
+
+#endif /*USE_LIBDNS*/
+
+
+/* Calling this function with YES set to True forces the use of the
+ * standard resolver even if dirmngr has been built with support for
+ * an alternative resolver.  */
+void
+enable_standard_resolver (int yes)
+{
+  standard_resolver = yes;
+}
+
+
+/* Return true if the standard resolver is used.  */
+int
+standard_resolver_p (void)
+{
+  return standard_resolver;
+}
+
+
+/* Calling this function with YES switches libdns into recursive mode.
+ * It has no effect on the standard resolver.  */
+void
+enable_recursive_resolver (int yes)
+{
+  recursive_resolver = yes;
+#ifdef USE_LIBDNS
+  libdns_reinit_pending = 1;
+#endif
+}
+
+
+/* Return true iff the recursive resolver is used.  */
+int
+recursive_resolver_p (void)
+{
+#if USE_LIBDNS
+  return !standard_resolver && recursive_resolver;
+#else
+  return 0;
+#endif
+}
+
+
+/* Puts this module eternally into Tor mode.  When called agained with
+ * NEW_CIRCUIT request a new TOR circuit for the next DNS query.  */
+void
+enable_dns_tormode (int new_circuit)
+{
+  if (!*tor_socks_user || new_circuit)
+    {
+      static unsigned int counter;
+
+      gpgrt_snprintf (tor_socks_user, sizeof tor_socks_user,
+                      "dirmngr-%lu", (unsigned long)getpid ());
+      gpgrt_snprintf (tor_socks_password, sizeof tor_socks_password,
+                      "p%u", counter);
+      counter++;
+    }
+  tor_mode = 1;
+}
+
+
+/* Disable tor mode.  */
+void
+disable_dns_tormode (void)
+{
+  tor_mode = 0;
+}
+
+
+/* Set verbosity and debug mode for this module. */
+void
+set_dns_verbose (int verbose, int debug)
+{
+  opt_verbose = verbose;
+  opt_debug = debug;
+}
+
+
+/* Set the Disable-IPv4 flag so that the name resolver does not return
+ * A addresses.  */
+void
+set_dns_disable_ipv4 (int yes)
+{
+  opt_disable_ipv4 = !!yes;
+}
+
+
+/* Set the Disable-IPv6 flag so that the name resolver does not return
+ * AAAA addresses.  */
+void
+set_dns_disable_ipv6 (int yes)
+{
+  opt_disable_ipv6 = !!yes;
+}
+
+
+/* Set the timeout for libdns requests to SECONDS.  A value of 0 sets
+ * the default timeout and values are capped at 10 minutes.  */
+void
+set_dns_timeout (int seconds)
+{
+  if (!seconds)
+    seconds = DEFAULT_TIMEOUT;
+  else if (seconds < 1)
+    seconds = 1;
+  else if (seconds > 600)
+    seconds = 600;
+
+  opt_timeout = seconds;
+}
+
+
+/* Change the default IP address of the nameserver to IPADDR.  The
+   address needs to be a numerical IP address and will be used for the
+   next DNS query.  Note that this is only used in Tor mode.  */
+void
+set_dns_nameserver (const char *ipaddr)
+{
+  strncpy (tor_nameserver, ipaddr? ipaddr : DEFAULT_NAMESERVER,
+           sizeof tor_nameserver -1);
+  tor_nameserver[sizeof tor_nameserver -1] = 0;
+#ifdef USE_LIBDNS
+  libdns_reinit_pending = 1;
+  libdns_tor_port = 0;  /* Start again with the default port.  */
+#endif
+}
+
+
+/* Free an addressinfo linked list as returned by resolve_dns_name.  */
+void
+free_dns_addrinfo (dns_addrinfo_t ai)
+{
+  while (ai)
+    {
+      dns_addrinfo_t next = ai->next;
+      xfree (ai);
+      ai = next;
+    }
+}
+
+
+#ifndef HAVE_W32_SYSTEM
+/* Return H_ERRNO mapped to a gpg-error code.  Will never return 0. */
+static gpg_error_t
+get_h_errno_as_gpg_error (void)
+{
+  gpg_err_code_t ec;
+
+  switch (h_errno)
+    {
+    case HOST_NOT_FOUND: ec = GPG_ERR_NO_NAME; break;
+    case TRY_AGAIN:      ec = GPG_ERR_TRY_LATER; break;
+    case NO_RECOVERY:    ec = GPG_ERR_SERVER_FAILED; break;
+    case NO_DATA:        ec = GPG_ERR_NO_DATA; break;
+    default:             ec = GPG_ERR_UNKNOWN_ERRNO; break;
+    }
+  return gpg_error (ec);
+}
+#endif /*!HAVE_W32_SYSTEM*/
+
+static gpg_error_t
+map_eai_to_gpg_error (int ec)
+{
+  gpg_error_t err;
+
+  switch (ec)
+    {
+    case EAI_AGAIN:     err = gpg_error (GPG_ERR_EAGAIN); break;
+    case EAI_BADFLAGS:  err = gpg_error (GPG_ERR_INV_FLAG); break;
+    case EAI_FAIL:      err = gpg_error (GPG_ERR_SERVER_FAILED); break;
+    case EAI_MEMORY:    err = gpg_error (GPG_ERR_ENOMEM); break;
+#ifdef EAI_NODATA
+    case EAI_NODATA:    err = gpg_error (GPG_ERR_NO_DATA); break;
+#endif
+    case EAI_NONAME:    err = gpg_error (GPG_ERR_NO_NAME); break;
+    case EAI_SERVICE:   err = gpg_error (GPG_ERR_NOT_SUPPORTED); break;
+    case EAI_FAMILY:    err = gpg_error (GPG_ERR_EAFNOSUPPORT); break;
+    case EAI_SOCKTYPE:  err = gpg_error (GPG_ERR_ESOCKTNOSUPPORT); break;
+#ifndef HAVE_W32_SYSTEM
+# ifdef EAI_ADDRFAMILY
+    case EAI_ADDRFAMILY:err = gpg_error (GPG_ERR_EADDRNOTAVAIL); break;
+# endif
+    case EAI_SYSTEM:    err = gpg_error_from_syserror (); break;
+#endif
+    default:            err = gpg_error (GPG_ERR_UNKNOWN_ERRNO); break;
+    }
+  return err;
+}
+
+
+#ifdef USE_LIBDNS
+static gpg_error_t
+libdns_error_to_gpg_error (int serr)
+{
+  gpg_err_code_t ec;
+
+  switch (serr)
+    {
+    case 0: ec = 0; break;
+
+    case DNS_ENOBUFS:  ec = GPG_ERR_BUFFER_TOO_SHORT; break;
+    case DNS_EILLEGAL: ec = GPG_ERR_INV_OBJ; break;
+    case DNS_EORDER:   ec = GPG_ERR_INV_ORDER; break;
+    case DNS_ESECTION: ec = GPG_ERR_DNS_SECTION; break;
+    case DNS_EUNKNOWN: ec = GPG_ERR_DNS_UNKNOWN; break;
+    case DNS_EADDRESS: ec = GPG_ERR_DNS_ADDRESS; break;
+    case DNS_ENOQUERY: ec = GPG_ERR_DNS_NO_QUERY; break;
+    case DNS_ENOANSWER:ec = GPG_ERR_DNS_NO_ANSWER; break;
+    case DNS_EFETCHED: ec = GPG_ERR_ALREADY_FETCHED; break;
+    case DNS_ESERVICE: ec = GPG_ERR_NOT_SUPPORTED; break;
+    case DNS_ENONAME:  ec = GPG_ERR_NO_NAME; break;
+    case DNS_EFAIL:    ec = GPG_ERR_SERVER_FAILED; break;
+    case DNS_ECONNFIN: ec = GPG_ERR_DNS_CLOSED; break;
+    case DNS_EVERIFY:  ec = GPG_ERR_DNS_VERIFY; break;
+
+    default:
+      if (serr >= 0)
+        ec = gpg_err_code_from_errno (serr);
+      else
+        ec = GPG_ERR_DNS_UNKNOWN;
+      break;
+    }
+  return gpg_error (ec);
+}
+#endif /*USE_LIBDNS*/
+
+
+/* Return true if resolve.conf changed since it was last loaded.  */
+#ifdef USE_LIBDNS
+static int
+resolv_conf_changed_p (void)
+{
+#if defined(HAVE_W32_SYSTEM) || !defined(HAVE_STAT)
+  return 0;
+#else
+  static time_t last_mtime;
+  const char *fname = RESOLV_CONF_NAME;
+  struct stat statbuf;
+  int changed = 0;
+
+  if (stat (fname, &statbuf))
+    {
+      log_error ("stat'ing '%s' failed: %s\n",
+                 fname, gpg_strerror (gpg_error_from_syserror ()));
+      last_mtime = 1; /* Force a "changed" result the next time stat
+                       * works.  */
+    }
+  else if (!last_mtime)
+    last_mtime = statbuf.st_mtime;
+  else if (last_mtime != statbuf.st_mtime)
+    {
+      changed = 1;
+      last_mtime = statbuf.st_mtime;
+    }
+
+  return changed;
+#endif
+}
+#endif /*USE_LIBDNS*/
+
+#ifdef USE_LIBDNS
+/* Initialize libdns.  Returns 0 on success; prints a diagnostic and
+ * returns an error code on failure.  */
+static gpg_error_t
+libdns_init (void)
+{
+  gpg_error_t err;
+  struct libdns_s ld;
+  int derr;
+  char *cfgstr = NULL;
+
+  if (libdns.resolv_conf)
+    return 0; /* Already initialized.  */
+
+  memset (&ld, 0, sizeof ld);
+
+  ld.resolv_conf = dns_resconf_open (&derr);
+  if (!ld.resolv_conf)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      log_error ("failed to allocate DNS resconf object: %s\n",
+                 gpg_strerror (err));
+      goto leave;
+    }
+
+  if (tor_mode)
+    {
+      if (!*tor_nameserver)
+        set_dns_nameserver (NULL);
+
+      if (!libdns_tor_port)
+        libdns_tor_port = TOR_PORT;
+
+      cfgstr = xtryasprintf ("[%s]:53", tor_nameserver);
+      if (!cfgstr)
+        err = gpg_error_from_syserror ();
+      else
+        err = libdns_error_to_gpg_error
+          (dns_resconf_pton (&ld.resolv_conf->nameserver[0], cfgstr));
+      if (err)
+        log_error ("failed to set nameserver '%s': %s\n",
+                   cfgstr, gpg_strerror (err));
+      if (err)
+        goto leave;
+
+      ld.resolv_conf->options.tcp = DNS_RESCONF_TCP_SOCKS;
+
+      xfree (cfgstr);
+      cfgstr = xtryasprintf ("[%s]:%d", "127.0.0.1", libdns_tor_port);
+      if (!cfgstr)
+        err = gpg_error_from_syserror ();
+      else
+        err = libdns_error_to_gpg_error
+          (dns_resconf_pton (&ld.socks_host, cfgstr));
+      if (err)
+        {
+          log_error ("failed to set socks server '%s': %s\n",
+                     cfgstr, gpg_strerror (err));
+          goto leave;
+        }
+    }
+  else
+    {
+#ifdef HAVE_W32_SYSTEM
+      ULONG ninfo_len;
+      PFIXED_INFO ninfo;
+      PIP_ADDR_STRING pip;
+      int idx;
+
+      ninfo_len = 2048;
+      ninfo = xtrymalloc (ninfo_len);
+      if (!ninfo)
+        {
+          err = gpg_error_from_syserror ();
+          goto leave;
+        }
+
+      if (GetNetworkParams (ninfo, &ninfo_len))
+        {
+          log_error ("GetNetworkParms failed: %s\n", w32_strerror (-1));
+          err = gpg_error (GPG_ERR_GENERAL);
+          xfree (ninfo);
+          goto leave;
+        }
+
+      for (idx=0, pip = &(ninfo->DnsServerList);
+           pip && idx < DIM (ld.resolv_conf->nameserver);
+           pip = pip->Next)
+        {
+          if (opt_debug)
+            log_debug ("dns: dnsserver[%d] '%s'\n", idx, pip->IpAddress.String);
+          err = libdns_error_to_gpg_error
+            (dns_resconf_pton (&ld.resolv_conf->nameserver[idx],
+                               pip->IpAddress.String));
+          if (err)
+            log_error ("failed to set nameserver[%d] '%s': %s\n",
+                       idx, pip->IpAddress.String, gpg_strerror (err));
+          else
+            idx++;
+        }
+      xfree (ninfo);
+
+#else /* Unix */
+      const char *fname;
+
+      fname = RESOLV_CONF_NAME;
+      resolv_conf_changed_p (); /* Reset timestamp.  */
+      err = libdns_error_to_gpg_error
+        (dns_resconf_loadpath (ld.resolv_conf, fname));
+      if (err)
+        {
+          log_error ("failed to load '%s': %s\n", fname, gpg_strerror (err));
+          goto leave;
+        }
+
+      fname = "/etc/nsswitch.conf";
+      err = libdns_error_to_gpg_error
+        (dns_nssconf_loadpath (ld.resolv_conf, fname));
+      if (err)
+        {
+          /* This is not a fatal error: nsswitch.conf is not used on
+           * all systems; assume classic behavior instead.  */
+          if (gpg_err_code (err) != GPG_ERR_ENOENT)
+            log_error ("failed to load '%s': %s\n", fname, gpg_strerror (err));
+          if (opt_debug)
+            log_debug ("dns: fallback resolution order, files then DNS\n");
+          ld.resolv_conf->lookup[0] = 'f';
+          ld.resolv_conf->lookup[1] = 'b';
+          ld.resolv_conf->lookup[2] = '\0';
+          err = GPG_ERR_NO_ERROR;
+        }
+      else if (!strchr (ld.resolv_conf->lookup, 'b'))
+        {
+          /* No DNS resolution type found in the list.  This might be
+           * due to systemd based systems which allow for custom
+           * keywords which are not known to us and thus we do not
+           * know whether DNS is wanted or not.  Because DNS is
+           * important for our infrastructure, we forcefully append
+           * DNS to the end of the list.  */
+          if (strlen (ld.resolv_conf->lookup)+2 < sizeof ld.resolv_conf->lookup)
+            {
+              if (opt_debug)
+                log_debug ("dns: appending DNS to resolution order\n");
+              strcat (ld.resolv_conf->lookup, "b");
+            }
+          else
+            log_error ("failed to append DNS to resolution order\n");
+        }
+
+#endif /* Unix */
+    }
+
+  ld.hosts = dns_hosts_open (&derr);
+  if (!ld.hosts)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      log_error ("failed to initialize hosts file: %s\n", gpg_strerror (err));
+      goto leave;
+    }
+
+  {
+#if HAVE_W32_SYSTEM
+    char *hosts_path = xtryasprintf ("%s\\System32\\drivers\\etc\\hosts",
+                                     getenv ("SystemRoot"));
+    if (! hosts_path)
+      {
+        err = gpg_error_from_syserror ();
+        goto leave;
+      }
+
+    derr = dns_hosts_loadpath (ld.hosts, hosts_path);
+    xfree (hosts_path);
+#else
+    derr = dns_hosts_loadpath (ld.hosts, "/etc/hosts");
+#endif
+    if (derr)
+      {
+        err = libdns_error_to_gpg_error (derr);
+        log_error ("failed to load hosts file: %s\n", gpg_strerror (err));
+        err = 0; /* Do not bail out - having no /etc/hosts is legal.  */
+      }
+  }
+
+  ld.resolv_conf->options.recurse = recursive_resolver_p ();
+
+  /* dns_hints_local for stub mode, dns_hints_root for recursive.  */
+  ld.hints = (recursive_resolver
+              ? dns_hints_root  (ld.resolv_conf, &derr)
+              : dns_hints_local (ld.resolv_conf, &derr));
+  if (!ld.hints)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      log_error ("failed to load DNS hints: %s\n", gpg_strerror (err));
+      goto leave;
+    }
+
+  /* All fine.  Make the data global.  */
+  libdns = ld;
+
+  if (opt_debug)
+    log_debug ("dns: libdns initialized%s\n", tor_mode?" (tor mode)":"");
+
+ leave:
+  xfree (cfgstr);
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+#ifdef USE_LIBDNS
+/* Deinitialize libdns.  */
+static void
+libdns_deinit (void)
+{
+  struct libdns_s ld;
+
+  if (!libdns.resolv_conf)
+    return; /* Not initialized.  */
+
+  ld = libdns;
+  memset (&libdns, 0, sizeof libdns);
+  dns_hints_close (ld.hints);
+  dns_hosts_close (ld.hosts);
+  dns_resconf_close (ld.resolv_conf);
+}
+#endif /*USE_LIBDNS*/
+
+
+/* SIGHUP action handler for this module.  With FORCE set objects are
+ * all immediately released. */
+void
+reload_dns_stuff (int force)
+{
+#ifdef USE_LIBDNS
+  if (force)
+    {
+      libdns_deinit ();
+      libdns_reinit_pending = 0;
+    }
+  else
+    {
+      libdns_reinit_pending = 1;
+      libdns_tor_port = 0;  /* Start again with the default port.  */
+    }
+#else
+  (void)force;
+#endif
+
+  /* We also flush the IPv4/v6 support flag cache.  */
+  cached_inet_support.valid = 0;
+}
+
+
+/* Called from time to time from the housekeeping thread.  */
+void
+dns_stuff_housekeeping (void)
+{
+  /* With the current housekeeping interval of 10 minutes we flush
+   * that case so that a new or removed interface will be detected not
+   * later than 10 minutes after it changed.  This way the user does
+   * not need a reload.  */
+  cached_inet_support.valid = 0;
+}
+
+
+#ifdef USE_LIBDNS
+/*
+ * Initialize libdns if needed and open a dns_resolver context.
+ * Returns 0 on success and stores the new context at R_RES.  On
+ * failure an error code is returned and NULL stored at R_RES.
+ */
+static gpg_error_t
+libdns_res_open (struct dns_resolver **r_res)
+{
+  gpg_error_t err;
+  struct dns_resolver *res;
+  int derr;
+  struct dns_options opts = { 0 };
+
+  opts.socks_host     = &libdns.socks_host;
+  opts.socks_user     = tor_socks_user;
+  opts.socks_password = tor_socks_password;
+
+  *r_res = NULL;
+
+  /* Force a reload if resolv.conf has changed.  */
+  if (resolv_conf_changed_p ())
+    {
+      if (opt_debug)
+        log_debug ("dns: resolv.conf changed - forcing reload\n");
+      libdns_reinit_pending = 1;
+    }
+
+  if (libdns_reinit_pending)
+    {
+      libdns_reinit_pending = 0;
+      libdns_deinit ();
+    }
+
+  err = libdns_init ();
+  if (err)
+    return err;
+
+  if (!opt_timeout)
+    set_dns_timeout (0);
+
+  res = dns_res_open (libdns.resolv_conf, libdns.hosts, libdns.hints, NULL,
+                      &opts, &derr);
+  if (!res)
+    return libdns_error_to_gpg_error (derr);
+
+  *r_res = res;
+  return 0;
+}
+#endif /*USE_LIBDNS*/
+
+
+#ifdef USE_LIBDNS
+/* Helper to test whether we need to try again after having switched
+ * the Tor port.  */
+static int
+libdns_switch_port_p (gpg_error_t err)
+{
+  if (tor_mode && gpg_err_code (err) == GPG_ERR_ECONNREFUSED
+      && libdns_tor_port == TOR_PORT)
+    {
+      /* Switch port and try again.  */
+      if (opt_debug)
+        log_debug ("dns: switching from SOCKS port %d to %d\n",
+                   TOR_PORT, TOR_PORT2);
+      libdns_tor_port = TOR_PORT2;
+      libdns_reinit_pending = 1;
+      return 1;
+    }
+  return 0;
+}
+#endif /*USE_LIBDNS*/
+
+
+#ifdef USE_LIBDNS
+/* Wrapper around dns_res_submit.  */
+static gpg_error_t
+libdns_res_submit (struct dns_resolver *res, const char *qname,
+                   enum dns_type qtype, enum dns_class qclass)
+{
+  return libdns_error_to_gpg_error (dns_res_submit (res, qname, qtype, qclass));
+}
+#endif /*USE_LIBDNS*/
+
+
+#ifdef USE_LIBDNS
+/* Standard event handling loop.  */
+gpg_error_t
+libdns_res_wait (struct dns_resolver *res)
+{
+  gpg_error_t err;
+
+  while ((err = libdns_error_to_gpg_error (dns_res_check (res)))
+         && gpg_err_code (err) == GPG_ERR_EAGAIN)
+    {
+      if (dns_res_elapsed (res) > opt_timeout)
+        {
+          err = gpg_error (GPG_ERR_DNS_TIMEOUT);
+          break;
+        }
+
+      my_unprotect ();
+      dns_res_poll (res, 1);
+      my_protect ();
+    }
+
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+#ifdef USE_LIBDNS
+static gpg_error_t
+resolve_name_libdns (const char *name, unsigned short port,
+                     int want_family, int want_socktype,
+                     dns_addrinfo_t *r_dai, char **r_canonname)
+{
+  gpg_error_t err;
+  dns_addrinfo_t daihead = NULL;
+  dns_addrinfo_t dai;
+  struct dns_resolver *res = NULL;
+  struct dns_addrinfo *ai = NULL;
+  struct addrinfo hints;
+  struct addrinfo *ent;
+  char portstr_[21];
+  char *portstr = NULL;
+  char *namebuf = NULL;
+  int derr;
+
+  *r_dai = NULL;
+  if (r_canonname)
+    *r_canonname = NULL;
+
+  memset (&hints, 0, sizeof hints);
+  hints.ai_family = want_family;
+  hints.ai_socktype = want_socktype;
+  hints.ai_flags = AI_ADDRCONFIG;
+  if (r_canonname)
+    hints.ai_flags |= AI_CANONNAME;
+
+  if (port)
+    {
+      snprintf (portstr_, sizeof portstr_, "%hu", port);
+      portstr = portstr_;
+    }
+
+  err = libdns_res_open (&res);
+  if (err)
+    goto leave;
+
+
+  if (is_ip_address (name))
+    {
+      hints.ai_flags |= AI_NUMERICHOST;
+      /* libdns does not grok brackets - remove them.  */
+      if (*name == '[' && name[strlen(name)-1] == ']')
+        {
+          namebuf = xtrymalloc (strlen (name));
+          if (!namebuf)
+            {
+              err = gpg_error_from_syserror ();
+              goto leave;
+            }
+          strcpy (namebuf, name+1);
+          namebuf[strlen (namebuf)-1] = 0;
+          name = namebuf;
+        }
+    }
+
+  ai = dns_ai_open (name, portstr, 0, &hints, res, &derr);
+  if (!ai)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      goto leave;
+    }
+
+  /* Loop over all records.  */
+  for (;;)
+    {
+      err = libdns_error_to_gpg_error (dns_ai_nextent (&ent, ai));
+      if (gpg_err_code (err) == GPG_ERR_ENOENT)
+        {
+          if (daihead)
+            err = 0; /* We got some results, we're good.  */
+          break; /* Ready.  */
+        }
+      if (gpg_err_code (err) == GPG_ERR_EAGAIN)
+        {
+          if (dns_ai_elapsed (ai) > opt_timeout)
+            {
+              err = gpg_error (GPG_ERR_DNS_TIMEOUT);
+              goto leave;
+            }
+
+          my_unprotect ();
+          dns_ai_poll (ai, 1);
+          my_protect ();
+          continue;
+        }
+      if (err)
+        goto leave;
+
+      if (r_canonname && ! *r_canonname && ent && ent->ai_canonname)
+        {
+          *r_canonname = xtrystrdup (ent->ai_canonname);
+          if (!*r_canonname)
+            {
+              err = gpg_error_from_syserror ();
+              goto leave;
+            }
+          /* Libdns appends the root zone part which is problematic
+           * for most other functions - strip it.  */
+          if (**r_canonname && (*r_canonname)[strlen (*r_canonname)-1] == '.')
+            (*r_canonname)[strlen (*r_canonname)-1] = 0;
+        }
+
+      dai = xtrymalloc (sizeof *dai);
+      if (dai == NULL)
+        {
+          err = gpg_error_from_syserror ();
+          goto leave;
+        }
+
+      dai->family = ent->ai_family;
+      dai->socktype = ent->ai_socktype;
+      dai->protocol = ent->ai_protocol;
+      dai->addrlen = ent->ai_addrlen;
+      memcpy (dai->addr, ent->ai_addr, ent->ai_addrlen);
+      dai->next = daihead;
+      daihead = dai;
+
+      xfree (ent);
+  }
+
+ leave:
+  dns_ai_close (ai);
+  dns_res_close (res);
+
+  if (err)
+    {
+      if (r_canonname)
+        {
+          xfree (*r_canonname);
+          *r_canonname = NULL;
+        }
+      free_dns_addrinfo (daihead);
+    }
+  else
+    *r_dai = daihead;
+
+  xfree (namebuf);
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+/* Resolve a name using the standard system function.  */
+static gpg_error_t
+resolve_name_standard (const char *name, unsigned short port,
+                       int want_family, int want_socktype,
+                       dns_addrinfo_t *r_dai, char **r_canonname)
+{
+  gpg_error_t err = 0;
+  dns_addrinfo_t daihead = NULL;
+  dns_addrinfo_t dai;
+  struct addrinfo *aibuf = NULL;
+  struct addrinfo hints, *ai;
+  char portstr[21];
+  int ret;
+
+  *r_dai = NULL;
+  if (r_canonname)
+    *r_canonname = NULL;
+
+  memset (&hints, 0, sizeof hints);
+  hints.ai_family = want_family;
+  hints.ai_socktype = want_socktype;
+  hints.ai_flags = AI_ADDRCONFIG;
+  if (r_canonname)
+    hints.ai_flags |= AI_CANONNAME;
+  if (is_ip_address (name))
+    hints.ai_flags |= AI_NUMERICHOST;
+
+  if (port)
+    snprintf (portstr, sizeof portstr, "%hu", port);
+  else
+    *portstr = 0;
+
+  /* We can't use the AI_IDN flag because that does the conversion
+     using the current locale.  However, GnuPG always used UTF-8.  To
+     support IDN we would need to make use of the libidn API.  */
+  ret = getaddrinfo (name, *portstr? portstr : NULL, &hints, &aibuf);
+  if (ret)
+    {
+      aibuf = NULL;
+      err = map_eai_to_gpg_error (ret);
+      if (gpg_err_code (err) == GPG_ERR_NO_NAME)
+        {
+          /* There seems to be a bug in the glibc getaddrinfo function
+             if the CNAME points to a long list of A and AAAA records
+             in which case the function return NO_NAME.  Let's do the
+             CNAME redirection again.  */
+          char *cname;
+
+          if (get_dns_cname (name, &cname))
+            goto leave; /* Still no success.  */
+
+          ret = getaddrinfo (cname, *portstr? portstr : NULL, &hints, &aibuf);
+          xfree (cname);
+          if (ret)
+            {
+              aibuf = NULL;
+              err = map_eai_to_gpg_error (ret);
+              goto leave;
+            }
+          err = 0; /* Yep, now it worked.  */
+        }
+      else
+        goto leave;
+    }
+
+  if (r_canonname && aibuf && aibuf->ai_canonname)
+    {
+      *r_canonname = xtrystrdup (aibuf->ai_canonname);
+      if (!*r_canonname)
+        {
+          err = gpg_error_from_syserror ();
+          goto leave;
+        }
+    }
+
+  for (ai = aibuf; ai; ai = ai->ai_next)
+    {
+      if (ai->ai_family != AF_INET6 && ai->ai_family != AF_INET)
+        continue;
+      if (opt_disable_ipv4 && ai->ai_family == AF_INET)
+        continue;
+      if (opt_disable_ipv6 && ai->ai_family == AF_INET6)
+        continue;
+
+      dai = xtrymalloc (sizeof *dai);
+      dai->family = ai->ai_family;
+      dai->socktype = ai->ai_socktype;
+      dai->protocol = ai->ai_protocol;
+      dai->addrlen = ai->ai_addrlen;
+      memcpy (dai->addr, ai->ai_addr, ai->ai_addrlen);
+      dai->next = daihead;
+      daihead = dai;
+    }
+
+ leave:
+  if (aibuf)
+    freeaddrinfo (aibuf);
+  if (err)
+    {
+      if (r_canonname)
+        {
+          xfree (*r_canonname);
+          *r_canonname = NULL;
+        }
+      free_dns_addrinfo (daihead);
+    }
+  else
+    *r_dai = daihead;
+  return err;
+}
+
+
+/* This a wrapper around getaddrinfo with slightly different semantics.
+   NAME is the name to resolve.
+   PORT is the requested port or 0.
+   WANT_FAMILY is either 0 (AF_UNSPEC), AF_INET6, or AF_INET4.
+   WANT_SOCKETTYPE is either SOCK_STREAM or SOCK_DGRAM.
+
+   On success the result is stored in a linked list with the head
+   stored at the address R_AI; the caller must call gpg_addrinfo_free
+   on this.  If R_CANONNAME is not NULL the official name of the host
+   is stored there as a malloced string; if that name is not available
+   NULL is stored.  */
+gpg_error_t
+resolve_dns_name (const char *name, unsigned short port,
+                  int want_family, int want_socktype,
+                  dns_addrinfo_t *r_ai, char **r_canonname)
+{
+  gpg_error_t err;
+
+#ifdef USE_LIBDNS
+  if (!standard_resolver)
+    {
+      err = resolve_name_libdns (name, port, want_family, want_socktype,
+                                  r_ai, r_canonname);
+      if (err && libdns_switch_port_p (err))
+        err = resolve_name_libdns (name, port, want_family, want_socktype,
+                                   r_ai, r_canonname);
+    }
+  else
+#endif /*USE_LIBDNS*/
+    err = resolve_name_standard (name, port, want_family, want_socktype,
+                                 r_ai, r_canonname);
+  if (opt_debug)
+    log_debug ("dns: resolve_dns_name(%s): %s\n", name, gpg_strerror (err));
+  return err;
+}
+
+
+#ifdef USE_LIBDNS
+/* Resolve an address using libdns.  */
+static gpg_error_t
+resolve_addr_libdns (const struct sockaddr_storage *addr, int addrlen,
+                     unsigned int flags, char **r_name)
+{
+  gpg_error_t err;
+  char host[DNS_D_MAXNAME + 1];
+  struct dns_resolver *res = NULL;
+  struct dns_packet *ans = NULL;
+  struct dns_ptr ptr;
+  int derr;
+
+  *r_name = NULL;
+
+  /* First we turn ADDR into a DNS name (with ".arpa" suffix).  */
+  err = 0;
+  if (addr->ss_family == AF_INET6)
+    {
+      const struct sockaddr_in6 *a6 = (const struct sockaddr_in6 *)addr;
+      if (!dns_aaaa_arpa (host, sizeof host, (void*)&a6->sin6_addr))
+        err = gpg_error (GPG_ERR_INV_OBJ);
+    }
+  else if (addr->ss_family == AF_INET)
+    {
+      const struct sockaddr_in *a4 = (const struct sockaddr_in *)addr;
+      if (!dns_a_arpa (host, sizeof host, (void*)&a4->sin_addr))
+        err = gpg_error (GPG_ERR_INV_OBJ);
+    }
+  else
+    err = gpg_error (GPG_ERR_EAFNOSUPPORT);
+  if (err)
+    goto leave;
+
+
+  err = libdns_res_open (&res);
+  if (err)
+    goto leave;
+
+  err = libdns_res_submit (res, host, DNS_T_PTR, DNS_C_IN);
+  if (err)
+    goto leave;
+
+  err = libdns_res_wait (res);
+  if (err)
+    goto leave;
+
+  ans = dns_res_fetch (res, &derr);
+  if (!ans)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      goto leave;
+    }
+
+  /* Check the rcode.  */
+  switch (dns_p_rcode (ans))
+    {
+    case DNS_RC_NOERROR:
+      break;
+    case DNS_RC_NXDOMAIN:
+      err = gpg_error (GPG_ERR_NO_NAME);
+      break;
+    default:
+      err = GPG_ERR_SERVER_FAILED;
+      goto leave;
+    }
+
+  /* Parse the result.  */
+  if (!err)
+    {
+      struct dns_rr rr;
+      struct dns_rr_i rri;
+
+      memset (&rri, 0, sizeof rri);
+      dns_rr_i_init (&rri);
+      rri.section = DNS_S_ALL & ~DNS_S_QD;
+      rri.name    = host;
+      rri.type    = DNS_T_PTR;
+
+      if (!dns_rr_grep (&rr, 1, &rri, ans, &derr))
+        {
+          err = gpg_error (GPG_ERR_NOT_FOUND);
+          goto leave;
+        }
+
+      err = libdns_error_to_gpg_error (dns_ptr_parse (&ptr, &rr, ans));
+      if (err)
+        goto leave;
+
+      /* Copy result.  */
+      *r_name = xtrystrdup (ptr.host);
+      if (!*r_name)
+        {
+          err = gpg_error_from_syserror ();
+          goto leave;
+        }
+      /* Libdns appends the root zone part which is problematic
+       * for most other functions - strip it.  */
+      if (**r_name && (*r_name)[strlen (*r_name)-1] == '.')
+        (*r_name)[strlen (*r_name)-1] = 0;
+    }
+  else /* GPG_ERR_NO_NAME */
+    {
+      char *buffer, *p;
+      int buflen;
+      int ec;
+
+      buffer = ptr.host;
+      buflen = sizeof ptr.host;
+
+      p = buffer;
+      if (addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
+        {
+          *p++ = '[';
+          buflen -= 2;
+        }
+      ec = getnameinfo ((const struct sockaddr *)addr,
+                        addrlen, p, buflen, NULL, 0, NI_NUMERICHOST);
+      if (ec)
+        {
+          err = map_eai_to_gpg_error (ec);
+          goto leave;
+        }
+      if (addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
+        strcat (buffer, "]");
+    }
+
+ leave:
+  dns_free (ans);
+  dns_res_close (res);
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+/* Resolve an address using the standard system function.  */
+static gpg_error_t
+resolve_addr_standard (const struct sockaddr_storage *addr, int addrlen,
+                       unsigned int flags, char **r_name)
+{
+  gpg_error_t err;
+  int ec;
+  char *buffer, *p;
+  int buflen;
+
+  *r_name = NULL;
+
+  buflen = NI_MAXHOST;
+  buffer = xtrymalloc (buflen + 2 + 1);
+  if (!buffer)
+    return gpg_error_from_syserror ();
+
+  if ((flags & DNS_NUMERICHOST) || tor_mode)
+    ec = EAI_NONAME;
+  else
+    ec = getnameinfo ((const struct sockaddr *)addr,
+                      addrlen, buffer, buflen, NULL, 0, NI_NAMEREQD);
+
+  if (!ec && *buffer == '[')
+    ec = EAI_FAIL;  /* A name may never start with a bracket.  */
+  else if (ec == EAI_NONAME)
+    {
+      p = buffer;
+      if (addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
+        {
+          *p++ = '[';
+          buflen -= 2;
+        }
+      ec = getnameinfo ((const struct sockaddr *)addr,
+                        addrlen, p, buflen, NULL, 0, NI_NUMERICHOST);
+      if (!ec && addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
+        strcat (buffer, "]");
+    }
+
+  if (ec)
+    err = map_eai_to_gpg_error (ec);
+  else
+    {
+      p = xtryrealloc (buffer, strlen (buffer)+1);
+      if (!p)
+        err = gpg_error_from_syserror ();
+      else
+        {
+          buffer = p;
+          err = 0;
+        }
+    }
+
+  if (err)
+    xfree (buffer);
+  else
+    *r_name = buffer;
+
+  return err;
+}
+
+
+/* A wrapper around getnameinfo.  */
+gpg_error_t
+resolve_dns_addr (const struct sockaddr_storage *addr, int addrlen,
+                  unsigned int flags, char **r_name)
+{
+  gpg_error_t err;
+
+#ifdef USE_LIBDNS
+  /* Note that we divert to the standard resolver for NUMERICHOST.  */
+  if (!standard_resolver && !(flags & DNS_NUMERICHOST))
+    {
+      err = resolve_addr_libdns (addr, addrlen, flags, r_name);
+      if (err && libdns_switch_port_p (err))
+        err = resolve_addr_libdns (addr, addrlen, flags, r_name);
+    }
+  else
+#endif /*USE_LIBDNS*/
+    err = resolve_addr_standard (addr, addrlen, flags, r_name);
+
+  if (opt_debug)
+    log_debug ("dns: resolve_dns_addr(): %s\n", gpg_strerror (err));
+  return err;
+}
+
+
+/* Check whether NAME is an IP address.  Returns a true if it is
+ * either an IPv6 or a IPv4 numerical address.  The actual return
+ * values can also be used to identify whether it is v4 or v6: The
+ * true value will surprisingly be 4 for IPv4 and 6 for IPv6.  */
+int
+is_ip_address (const char *name)
+{
+  const char *s;
+  int ndots, dblcol, n;
+
+  if (*name == '[')
+    return 6; /* yes: A legal DNS name may not contain this character;
+                 this must be bracketed v6 address.  */
+  if (*name == '.')
+    return 0; /* No.  A leading dot is not a valid IP address.  */
+
+  /* Check whether this is a v6 address.  */
+  ndots = n = dblcol = 0;
+  for (s=name; *s; s++)
+    {
+      if (*s == ':')
+        {
+          ndots++;
+          if (s[1] == ':')
+            {
+              ndots++;
+              if (dblcol)
+                return 0; /* No: Only one "::" allowed.  */
+              dblcol++;
+              if (s[1])
+                s++;
+            }
+          n = 0;
+        }
+      else if (*s == '.')
+        goto legacy;
+      else if (!strchr ("0123456789abcdefABCDEF", *s))
+        return 0; /* No: Not a hex digit.  */
+      else if (++n > 4)
+        return 0; /* To many digits in a group.  */
+    }
+  if (ndots > 7)
+    return 0; /* No: Too many colons.  */
+  else if (ndots > 1)
+    return 6; /* Yes: At least 2 colons indicate an v6 address.  */
+
+ legacy:
+  /* Check whether it is legacy IP address.  */
+  ndots = n = 0;
+  for (s=name; *s; s++)
+    {
+      if (*s == '.')
+        {
+          if (s[1] == '.')
+            return 0; /* No:  Double dot. */
+          if (atoi (s+1) > 255)
+            return 0; /* No:  Ipv4 byte value too large.  */
+          ndots++;
+          n = 0;
+        }
+      else if (!strchr ("0123456789", *s))
+        return 0; /* No: Not a digit.  */
+      else if (++n > 3)
+        return 0; /* No: More than 3 digits.  */
+    }
+  return (ndots == 3)? 4 : 0;
+}
+
+
+/* Return true if NAME is an onion address.  */
+int
+is_onion_address (const char *name)
+{
+  size_t len;
+
+  len = name? strlen (name) : 0;
+  if (len < 8 || strcmp (name + len - 6, ".onion"))
+    return 0;
+  /* Note that we require at least 2 characters before the suffix.  */
+  return 1;  /* Yes.  */
+}
+
+
+/* libdns version of get_dns_cert.  */
+#ifdef USE_LIBDNS
+static gpg_error_t
+get_dns_cert_libdns (const char *name, int want_certtype,
+                     void **r_key, size_t *r_keylen,
+                     unsigned char **r_fpr, size_t *r_fprlen, char **r_url)
+{
+  gpg_error_t err;
+  struct dns_resolver *res = NULL;
+  struct dns_packet *ans = NULL;
+  struct dns_rr rr;
+  struct dns_rr_i rri;
+  char host[DNS_D_MAXNAME + 1];
+  int derr;
+  int qtype;
+
+  /* Get the query type from WANT_CERTTYPE (which in general indicates
+   * the subtype we want). */
+  qtype = (want_certtype < DNS_CERTTYPE_RRBASE
+           ? T_CERT
+           : (want_certtype - DNS_CERTTYPE_RRBASE));
+
+
+  err = libdns_res_open (&res);
+  if (err)
+    goto leave;
+
+  if (dns_d_anchor (host, sizeof host, name, strlen (name)) >= sizeof host)
+    {
+      err = gpg_error (GPG_ERR_ENAMETOOLONG);
+      goto leave;
+    }
+
+  err = libdns_res_submit (res, name, qtype, DNS_C_IN);
+  if (err)
+    goto leave;
+
+  err = libdns_res_wait (res);
+  if (err)
+    goto leave;
+
+  ans = dns_res_fetch (res, &derr);
+  if (!ans)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      goto leave;
+    }
+
+  /* Check the rcode.  */
+  switch (dns_p_rcode (ans))
+    {
+    case DNS_RC_NOERROR: break;
+    case DNS_RC_NXDOMAIN: err = gpg_error (GPG_ERR_NO_NAME); break;
+    default: err = GPG_ERR_SERVER_FAILED; break;
+    }
+  if (err)
+    goto leave;
+
+  memset (&rri, 0, sizeof rri);
+  dns_rr_i_init (&rri);
+  rri.section = DNS_S_ALL & ~DNS_S_QD;
+  rri.name    = host;
+  rri.type    = qtype;
+
+  err = gpg_error (GPG_ERR_NOT_FOUND);
+  while (dns_rr_grep (&rr, 1, &rri, ans, &derr))
+    {
+      unsigned char *rp  = ans->data + rr.rd.p;
+      unsigned short len = rr.rd.len;
+      u16 subtype;
+
+       if (!len)
+        {
+          /* Definitely too short - skip.  */
+        }
+      else if (want_certtype >= DNS_CERTTYPE_RRBASE
+          && rr.type == (want_certtype - DNS_CERTTYPE_RRBASE)
+          && r_key)
+        {
+          *r_key = xtrymalloc (len);
+          if (!*r_key)
+            err = gpg_error_from_syserror ();
+          else
+            {
+              memcpy (*r_key, rp, len);
+              *r_keylen = len;
+              err = 0;
+            }
+          goto leave;
+        }
+      else if (want_certtype >= DNS_CERTTYPE_RRBASE)
+        {
+          /* We did not found the requested RR - skip. */
+        }
+      else if (rr.type == T_CERT && len > 5)
+        {
+          /* We got a CERT type.   */
+          subtype = buf16_to_u16 (rp);
+          rp += 2; len -= 2;
+
+          /* Skip the CERT key tag and algo which we don't need.  */
+          rp += 3; len -= 3;
+
+          if (want_certtype && want_certtype != subtype)
+            ; /* Not the requested subtype - skip.  */
+          else if (subtype == DNS_CERTTYPE_PGP && len && r_key && r_keylen)
+            {
+              /* PGP subtype */
+              *r_key = xtrymalloc (len);
+              if (!*r_key)
+                err = gpg_error_from_syserror ();
+              else
+                {
+                  memcpy (*r_key, rp, len);
+                  *r_keylen = len;
+                  err = 0;
+                }
+              goto leave;
+            }
+          else if (subtype == DNS_CERTTYPE_IPGP
+                   && len && len < 1023 && len >= rp[0] + 1)
+            {
+              /* IPGP type */
+              *r_fprlen = rp[0];
+              if (*r_fprlen)
+                {
+                  *r_fpr = xtrymalloc (*r_fprlen);
+                  if (!*r_fpr)
+                    {
+                      err = gpg_error_from_syserror ();
+                      goto leave;
+                    }
+                  memcpy (*r_fpr, rp+1, *r_fprlen);
+                }
+              else
+                *r_fpr = NULL;
+
+              if (len > *r_fprlen + 1)
+                {
+                  *r_url = xtrymalloc (len - (*r_fprlen + 1) + 1);
+                  if (!*r_url)
+                    {
+                      err = gpg_error_from_syserror ();
+                      xfree (*r_fpr);
+                      *r_fpr = NULL;
+                      goto leave;
+                    }
+                  memcpy (*r_url, rp + *r_fprlen + 1, len - (*r_fprlen + 1));
+                  (*r_url)[len - (*r_fprlen + 1)] = 0;
+                }
+              else
+                *r_url = NULL;
+
+              err = 0;
+              goto leave;
+            }
+          else
+            {
+              /* Unknown subtype or record too short - skip.  */
+            }
+        }
+      else
+        {
+          /* Not a requested type - skip.  */
+        }
+    }
+
+ leave:
+  dns_free (ans);
+  dns_res_close (res);
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+/* Standard resolver version of get_dns_cert.  */
+static gpg_error_t
+get_dns_cert_standard (const char *name, int want_certtype,
+                       void **r_key, size_t *r_keylen,
+                       unsigned char **r_fpr, size_t *r_fprlen, char **r_url)
+{
+#ifdef HAVE_SYSTEM_RESOLVER
+  gpg_error_t err;
+  unsigned char *answer;
+  int r;
+  u16 count;
+
+  /* Allocate a 64k buffer which is the limit for an DNS response.  */
+  answer = xtrymalloc (65536);
+  if (!answer)
+    return gpg_error_from_syserror ();
+
+  err = gpg_error (GPG_ERR_NOT_FOUND);
+  r = res_query (name, C_IN,
+                 (want_certtype < DNS_CERTTYPE_RRBASE
+                  ? T_CERT
+                  : (want_certtype - DNS_CERTTYPE_RRBASE)),
+                 answer, 65536);
+  /* Not too big, not too small, no errors and at least 1 answer. */
+  if (r >= sizeof (HEADER) && r <= 65536
+      && (((HEADER *)(void *) answer)->rcode) == NOERROR
+      && (count = ntohs (((HEADER *)(void *) answer)->ancount)))
+    {
+      int rc;
+      unsigned char *pt, *emsg;
+
+      emsg = &answer[r];
+
+      pt = &answer[sizeof (HEADER)];
+
+      /* Skip over the query */
+
+      rc = dn_skipname (pt, emsg);
+      if (rc == -1)
+        {
+          err = gpg_error (GPG_ERR_INV_OBJ);
+          goto leave;
+        }
+      pt += rc + QFIXEDSZ;
+
+      /* There are several possible response types for a CERT request.
+         We're interested in the PGP (a key) and IPGP (a URI) types.
+         Skip all others.  TODO: A key is better than a URI since
+         we've gone through all this bother to fetch it, so favor that
+         if we have both PGP and IPGP? */
+
+      while (count-- > 0 && pt < emsg)
+        {
+          u16 type, class, dlen, ctype;
+
+          rc = dn_skipname (pt, emsg);  /* the name we just queried for */
+          if (rc == -1)
+            {
+              err = gpg_error (GPG_ERR_INV_OBJ);
+              goto leave;
+            }
+
+          pt += rc;
+
+          /* Truncated message? 15 bytes takes us to the point where
+             we start looking at the ctype. */
+          if ((emsg - pt) < 15)
+            break;
+
+          type = buf16_to_u16 (pt);
+          pt += 2;
+
+          class = buf16_to_u16 (pt);
+          pt += 2;
+
+          if (class != C_IN)
+            break;
+
+          /* ttl */
+          pt += 4;
+
+          /* data length */
+          dlen = buf16_to_u16 (pt);
+          pt += 2;
+
+          /* Check the type and parse.  */
+          if (want_certtype >= DNS_CERTTYPE_RRBASE
+              && type == (want_certtype - DNS_CERTTYPE_RRBASE)
+              && r_key)
+            {
+              *r_key = xtrymalloc (dlen);
+              if (!*r_key)
+                err = gpg_error_from_syserror ();
+              else
+                {
+                  memcpy (*r_key, pt, dlen);
+                  *r_keylen = dlen;
+                  err = 0;
+                }
+              goto leave;
+            }
+          else if (want_certtype >= DNS_CERTTYPE_RRBASE)
+            {
+              /* We did not found the requested RR.  */
+              pt += dlen;
+            }
+          else if (type == T_CERT)
+            {
+              /* We got a CERT type.   */
+              ctype = buf16_to_u16 (pt);
+              pt += 2;
+
+              /* Skip the CERT key tag and algo which we don't need. */
+              pt += 3;
+
+              dlen -= 5;
+
+              /* 15 bytes takes us to here */
+              if (want_certtype && want_certtype != ctype)
+                ; /* Not of the requested certtype.  */
+              else if (ctype == DNS_CERTTYPE_PGP && dlen && r_key && r_keylen)
+                {
+                  /* PGP type */
+                  *r_key = xtrymalloc (dlen);
+                  if (!*r_key)
+                    err = gpg_error_from_syserror ();
+                  else
+                    {
+                      memcpy (*r_key, pt, dlen);
+                      *r_keylen = dlen;
+                      err = 0;
+                    }
+                  goto leave;
+                }
+              else if (ctype == DNS_CERTTYPE_IPGP
+                       && dlen && dlen < 1023 && dlen >= pt[0] + 1)
+                {
+                  /* IPGP type */
+                  *r_fprlen = pt[0];
+                  if (*r_fprlen)
+                    {
+                      *r_fpr = xtrymalloc (*r_fprlen);
+                      if (!*r_fpr)
+                        {
+                          err = gpg_error_from_syserror ();
+                          goto leave;
+                        }
+                      memcpy (*r_fpr, &pt[1], *r_fprlen);
+                    }
+                  else
+                    *r_fpr = NULL;
+
+                  if (dlen > *r_fprlen + 1)
+                    {
+                      *r_url = xtrymalloc (dlen - (*r_fprlen + 1) + 1);
+                      if (!*r_url)
+                        {
+                          err = gpg_error_from_syserror ();
+                          xfree (*r_fpr);
+                          *r_fpr = NULL;
+                          goto leave;
+                        }
+                      memcpy (*r_url, &pt[*r_fprlen + 1],
+                              dlen - (*r_fprlen + 1));
+                      (*r_url)[dlen - (*r_fprlen + 1)] = '\0';
+                    }
+                  else
+                    *r_url = NULL;
+
+                  err = 0;
+                  goto leave;
+                }
+
+              /* No subtype matches, so continue with the next answer. */
+              pt += dlen;
+            }
+          else
+            {
+              /* Not a requested type - might be a CNAME. Try next item.  */
+              pt += dlen;
+            }
+        }
+    }
+
+ leave:
+  xfree (answer);
+  return err;
+
+#else /*!HAVE_SYSTEM_RESOLVER*/
+
+  (void)name;
+  (void)want_certtype;
+  (void)r_key;
+  (void)r_keylen;
+  (void)r_fpr;
+  (void)r_fprlen;
+  (void)r_url;
+  return gpg_error (GPG_ERR_NOT_SUPPORTED);
+
+#endif /*!HAVE_SYSTEM_RESOLVER*/
+}
+
+
+/* Returns 0 on success or an error code.  If a PGP CERT record was
+   found, the malloced data is returned at (R_KEY, R_KEYLEN) and
+   the other return parameters are set to NULL/0.  If an IPGP CERT
+   record was found the fingerprint is stored as an allocated block at
+   R_FPR and its length at R_FPRLEN; an URL is allocated as a
+   string and returned at R_URL.  If WANT_CERTTYPE is 0 this function
+   returns the first CERT found with a supported type; it is expected
+   that only one CERT record is used.  If WANT_CERTTYPE is one of the
+   supported certtypes only records with this certtype are considered
+   and the first found is returned.  (R_KEY,R_KEYLEN) are optional. */
+gpg_error_t
+get_dns_cert (const char *name, int want_certtype,
+              void **r_key, size_t *r_keylen,
+              unsigned char **r_fpr, size_t *r_fprlen, char **r_url)
+{
+  gpg_error_t err;
+
+  if (r_key)
+    *r_key = NULL;
+  if (r_keylen)
+    *r_keylen = 0;
+  *r_fpr = NULL;
+  *r_fprlen = 0;
+  *r_url = NULL;
+
+#ifdef USE_LIBDNS
+  if (!standard_resolver)
+    {
+      err = get_dns_cert_libdns (name, want_certtype, r_key, r_keylen,
+                                 r_fpr, r_fprlen, r_url);
+      if (err && libdns_switch_port_p (err))
+        err = get_dns_cert_libdns (name, want_certtype, r_key, r_keylen,
+                                   r_fpr, r_fprlen, r_url);
+    }
+  else
+#endif /*USE_LIBDNS*/
+    err = get_dns_cert_standard (name, want_certtype, r_key, r_keylen,
+                                 r_fpr, r_fprlen, r_url);
+
+  if (opt_debug)
+    log_debug ("dns: get_dns_cert(%s): %s\n", name, gpg_strerror (err));
+  return err;
+}
+
+
+static int
+priosort(const void *a,const void *b)
+{
+  const struct srventry *sa=a,*sb=b;
+  if(sa->priority>sb->priority)
+    return 1;
+  else if(sa->priority<sb->priority)
+    return -1;
+  else
+    return 0;
+}
+
+
+/* Libdns based helper for getsrv.  Note that it is expected that NULL
+ * is stored at the address of LIST and 0 is stored at the address of
+ * R_COUNT.  */
+#ifdef USE_LIBDNS
+static gpg_error_t
+getsrv_libdns (const char *name, struct srventry **list, unsigned int *r_count)
+{
+  gpg_error_t err;
+  struct dns_resolver *res = NULL;
+  struct dns_packet *ans = NULL;
+  struct dns_rr rr;
+  struct dns_rr_i rri;
+  char host[DNS_D_MAXNAME + 1];
+  int derr;
+  unsigned int srvcount = 0;
+
+  err = libdns_res_open (&res);
+  if (err)
+    goto leave;
+
+  if (dns_d_anchor (host, sizeof host, name, strlen (name)) >= sizeof host)
+    {
+      err = gpg_error (GPG_ERR_ENAMETOOLONG);
+      goto leave;
+    }
+
+  err = libdns_res_submit (res, name, DNS_T_SRV, DNS_C_IN);
+  if (err)
+    goto leave;
+
+  err = libdns_res_wait (res);
+  if (err)
+    goto leave;
+
+  ans = dns_res_fetch (res, &derr);
+  if (!ans)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      goto leave;
+    }
+
+  /* Check the rcode.  */
+  switch (dns_p_rcode (ans))
+    {
+    case DNS_RC_NOERROR: break;
+    case DNS_RC_NXDOMAIN: err = gpg_error (GPG_ERR_NO_NAME); break;
+    default: err = GPG_ERR_SERVER_FAILED; break;
+    }
+  if (err)
+    goto leave;
+
+  memset (&rri, 0, sizeof rri);
+  dns_rr_i_init (&rri);
+  rri.section = DNS_S_ALL & ~DNS_S_QD;
+  rri.name	  = host;
+  rri.type	  = DNS_T_SRV;
+
+  while (dns_rr_grep (&rr, 1, &rri, ans, &derr))
+    {
+      struct dns_srv dsrv;
+      struct srventry *srv;
+      struct srventry *newlist;
+
+      err = libdns_error_to_gpg_error (dns_srv_parse(&dsrv, &rr, ans));
+      if (err)
+        goto leave;
+
+      newlist = xtryrealloc (*list, (srvcount+1)*sizeof(struct srventry));
+      if (!newlist)
+        {
+          err = gpg_error_from_syserror ();
+          goto leave;
+        }
+      *list = newlist;
+      memset (&(*list)[srvcount], 0, sizeof(struct srventry));
+      srv = &(*list)[srvcount];
+      srvcount++;
+      srv->priority = dsrv.priority;
+      srv->weight   = dsrv.weight;
+      srv->port     = dsrv.port;
+      mem2str (srv->target, dsrv.target, sizeof srv->target);
+      /* Libdns appends the root zone part which is problematic for
+       * most other functions - strip it.  */
+      if (*srv->target && (srv->target)[strlen (srv->target)-1] == '.')
+        (srv->target)[strlen (srv->target)-1] = 0;
+    }
+
+  *r_count = srvcount;
+
+ leave:
+  if (err)
+    {
+      xfree (*list);
+      *list = NULL;
+    }
+  dns_free (ans);
+  dns_res_close (res);
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+/* Standard resolver based helper for getsrv.  Note that it is
+ * expected that NULL is stored at the address of LIST and 0 is stored
+ * at the address of R_COUNT.  */
+static gpg_error_t
+getsrv_standard (const char *name,
+                 struct srventry **list, unsigned int *r_count)
+{
+#ifdef HAVE_SYSTEM_RESOLVER
+  union {
+    unsigned char ans[2048];
+    HEADER header[1];
+  } res;
+  unsigned char *answer = res.ans;
+  HEADER *header = res.header;
+  unsigned char *pt, *emsg;
+  int r, rc;
+  u16 dlen;
+  unsigned int srvcount = 0;
+  u16 count;
+
+  /* Do not allow a query using the standard resolver in Tor mode.  */
+  if (tor_mode)
+    return gpg_error (GPG_ERR_NOT_ENABLED);
+
+  my_unprotect ();
+  r = res_query (name, C_IN, T_SRV, answer, sizeof res.ans);
+  my_protect ();
+  if (r < 0)
+    return get_h_errno_as_gpg_error ();
+  if (r < sizeof (HEADER))
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+  if (r > sizeof res.ans)
+    return gpg_error (GPG_ERR_SYSTEM_BUG);
+  if (header->rcode != NOERROR || !(count=ntohs (header->ancount)))
+    return gpg_error (GPG_ERR_NO_NAME); /* Error or no record found.  */
+
+  emsg = &answer[r];
+  pt = &answer[sizeof(HEADER)];
+
+  /* Skip over the query */
+  rc = dn_skipname (pt, emsg);
+  if (rc == -1)
+    goto fail;
+
+  pt += rc + QFIXEDSZ;
+
+  while (count-- > 0 && pt < emsg)
+    {
+      struct srventry *srv;
+      u16 type, class;
+      struct srventry *newlist;
+
+      newlist = xtryrealloc (*list, (srvcount+1)*sizeof(struct srventry));
+      if (!newlist)
+        goto fail;
+      *list = newlist;
+      memset (&(*list)[srvcount], 0, sizeof(struct srventry));
+      srv = &(*list)[srvcount];
+      srvcount++;
+
+      rc = dn_skipname (pt, emsg); /* The name we just queried for.  */
+      if (rc == -1)
+        goto fail;
+      pt += rc;
+
+      /* Truncated message? */
+      if ((emsg-pt) < 16)
+        goto fail;
+
+      type = buf16_to_u16 (pt);
+      pt += 2;
+      /* We asked for SRV and got something else !? */
+      if (type != T_SRV)
+        goto fail;
+
+      class = buf16_to_u16 (pt);
+      pt += 2;
+      /* We asked for IN and got something else !? */
+      if (class != C_IN)
+        goto fail;
+
+      pt += 4; /* ttl */
+      dlen = buf16_to_u16 (pt);
+      pt += 2;
+
+      srv->priority = buf16_to_ushort (pt);
+      pt += 2;
+      srv->weight = buf16_to_ushort (pt);
+      pt += 2;
+      srv->port = buf16_to_ushort (pt);
+      pt += 2;
+
+      /* Get the name.  2782 doesn't allow name compression, but
+       * dn_expand still works to pull the name out of the packet. */
+      rc = dn_expand (answer, emsg, pt, srv->target, sizeof srv->target);
+      if (rc == 1 && srv->target[0] == 0) /* "." */
+        {
+          xfree(*list);
+          *list = NULL;
+          return 0;
+        }
+      if (rc == -1)
+        goto fail;
+      pt += rc;
+      /* Corrupt packet? */
+      if (dlen != rc+6)
+        goto fail;
+    }
+
+  *r_count = srvcount;
+  return 0;
+
+ fail:
+  xfree (*list);
+  *list = NULL;
+  return gpg_error (GPG_ERR_GENERAL);
+
+#else /*!HAVE_SYSTEM_RESOLVER*/
+
+  (void)name;
+  (void)list;
+  (void)r_count;
+  return gpg_error (GPG_ERR_NOT_SUPPORTED);
+
+#endif /*!HAVE_SYSTEM_RESOLVER*/
+}
+
+
+/* Query a SRV record for SERVICE and PROTO for NAME.  If SERVICE is
+ * NULL, NAME is expected to contain the full query name.  Note that
+ * we do not return NONAME but simply store 0 at R_COUNT.  On error an
+ * error code is returned and 0 stored at R_COUNT.  */
+gpg_error_t
+get_dns_srv (const char *name, const char *service, const char *proto,
+             struct srventry **list, unsigned int *r_count)
+{
+  gpg_error_t err;
+  char *namebuffer = NULL;
+  unsigned int srvcount;
+  int i;
+
+  *list = NULL;
+  *r_count = 0;
+  srvcount = 0;
+
+  /* If SERVICE is given construct the query from it and PROTO.  */
+  if (service)
+    {
+      namebuffer = xtryasprintf ("_%s._%s.%s",
+                                 service, proto? proto:"tcp", name);
+      if (!namebuffer)
+        {
+          err = gpg_error_from_syserror ();
+          goto leave;
+        }
+      name = namebuffer;
+    }
+
+
+#ifdef USE_LIBDNS
+  if (!standard_resolver)
+    {
+      err = getsrv_libdns (name, list, &srvcount);
+      if (err && libdns_switch_port_p (err))
+        err = getsrv_libdns (name, list, &srvcount);
+    }
+  else
+#endif /*USE_LIBDNS*/
+    err = getsrv_standard (name, list, &srvcount);
+
+  if (err)
+    {
+      if (gpg_err_code (err) == GPG_ERR_NO_NAME)
+        err = 0;
+      goto leave;
+    }
+
+  /* Now we have an array of all the srv records. */
+
+  /* Order by priority */
+  qsort(*list,srvcount,sizeof(struct srventry),priosort);
+
+  /* For each priority, move the zero-weighted items first. */
+  for (i=0; i < srvcount; i++)
+    {
+      int j;
+
+      for (j=i;j < srvcount && (*list)[i].priority == (*list)[j].priority; j++)
+        {
+          if((*list)[j].weight==0)
+            {
+              /* Swap j with i */
+              if(j!=i)
+                {
+                  struct srventry temp;
+
+                  memcpy (&temp,&(*list)[j],sizeof(struct srventry));
+                  memcpy (&(*list)[j],&(*list)[i],sizeof(struct srventry));
+                  memcpy (&(*list)[i],&temp,sizeof(struct srventry));
+                }
+
+              break;
+            }
+        }
+    }
+
+  /* Run the RFC-2782 weighting algorithm.  We don't need very high
+     quality randomness for this, so regular libc srand/rand is
+     sufficient.  */
+
+  {
+    static int done;
+    if (!done)
+      {
+        done = 1;
+        srand (time (NULL)*getpid());
+      }
+  }
+
+  for (i=0; i < srvcount; i++)
+    {
+      int j;
+      float prio_count=0,chose;
+
+      for (j=i; j < srvcount && (*list)[i].priority == (*list)[j].priority; j++)
+        {
+          prio_count+=(*list)[j].weight;
+          (*list)[j].run_count=prio_count;
+        }
+
+      chose=prio_count*rand()/RAND_MAX;
+
+      for (j=i;j<srvcount && (*list)[i].priority==(*list)[j].priority;j++)
+        {
+          if (chose<=(*list)[j].run_count)
+            {
+              /* Swap j with i */
+              if(j!=i)
+                {
+                  struct srventry temp;
+
+                  memcpy(&temp,&(*list)[j],sizeof(struct srventry));
+                  memcpy(&(*list)[j],&(*list)[i],sizeof(struct srventry));
+                  memcpy(&(*list)[i],&temp,sizeof(struct srventry));
+                }
+              break;
+            }
+        }
+    }
+
+ leave:
+  if (opt_debug)
+    {
+      if (err)
+        log_debug ("dns: getsrv(%s): %s\n", name, gpg_strerror (err));
+      else
+        log_debug ("dns: getsrv(%s) -> %u records\n", name, srvcount);
+    }
+  if (!err)
+    *r_count = srvcount;
+  xfree (namebuffer);
+  return err;
+}
+
+
+
+#ifdef USE_LIBDNS
+/* libdns version of get_dns_cname.  */
+gpg_error_t
+get_dns_cname_libdns (const char *name, char **r_cname)
+{
+  gpg_error_t err;
+  struct dns_resolver *res;
+  struct dns_packet *ans = NULL;
+  struct dns_cname cname;
+  int derr;
+
+  err = libdns_res_open (&res);
+  if (err)
+    goto leave;
+
+  err = libdns_res_submit (res, name, DNS_T_CNAME, DNS_C_IN);
+  if (err)
+    goto leave;
+
+  err = libdns_res_wait (res);
+  if (err)
+    goto leave;
+
+  ans = dns_res_fetch (res, &derr);
+  if (!ans)
+    {
+      err = libdns_error_to_gpg_error (derr);
+      goto leave;
+    }
+
+  /* Check the rcode.  */
+  switch (dns_p_rcode (ans))
+    {
+    case DNS_RC_NOERROR: break;
+    case DNS_RC_NXDOMAIN: err = gpg_error (GPG_ERR_NO_NAME); break;
+    default: err = GPG_ERR_SERVER_FAILED; break;
+    }
+  if (err)
+    goto leave;
+
+  /* Parse the result into CNAME.  */
+  err = libdns_error_to_gpg_error (dns_p_study (ans));
+  if (err)
+    goto leave;
+
+  if (!dns_d_cname (&cname, sizeof cname, name, strlen (name), ans, &derr))
+    {
+      err = libdns_error_to_gpg_error (derr);
+      goto leave;
+    }
+
+  /* Copy result.  */
+  *r_cname = xtrystrdup (cname.host);
+  if (!*r_cname)
+    err = gpg_error_from_syserror ();
+  else
+    {
+      /* Libdns appends the root zone part which is problematic
+       * for most other functions - strip it.  */
+      if (**r_cname && (*r_cname)[strlen (*r_cname)-1] == '.')
+        (*r_cname)[strlen (*r_cname)-1] = 0;
+    }
+
+ leave:
+  dns_free (ans);
+  dns_res_close (res);
+  return err;
+}
+#endif /*USE_LIBDNS*/
+
+
+/* Standard resolver version of get_dns_cname.  */
+gpg_error_t
+get_dns_cname_standard (const char *name, char **r_cname)
+{
+#ifdef HAVE_SYSTEM_RESOLVER
+  gpg_error_t err;
+  int rc;
+  union {
+    unsigned char ans[2048];
+    HEADER header[1];
+  } res;
+  unsigned char *answer = res.ans;
+  HEADER *header = res.header;
+  unsigned char *pt, *emsg;
+  int r;
+  char *cname;
+  int cnamesize = 1025;
+  u16 count;
+
+  /* Do not allow a query using the standard resolver in Tor mode.  */
+  if (tor_mode)
+    return -1;
+
+  my_unprotect ();
+  r = res_query (name, C_IN, T_CERT, answer, sizeof res.ans);
+  my_protect ();
+  if (r < 0)
+    return get_h_errno_as_gpg_error ();
+  if (r < sizeof (HEADER))
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+  if (r > sizeof res.ans)
+    return gpg_error (GPG_ERR_SYSTEM_BUG);
+  if (header->rcode != NOERROR || !(count=ntohs (header->ancount)))
+    return gpg_error (GPG_ERR_NO_NAME); /* Error or no record found.  */
+  if (count != 1)
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+
+  emsg = &answer[r];
+  pt = &answer[sizeof(HEADER)];
+  rc = dn_skipname (pt, emsg);
+  if (rc == -1)
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+
+  pt += rc + QFIXEDSZ;
+  if (pt >= emsg)
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+
+  rc = dn_skipname (pt, emsg);
+  if (rc == -1)
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+  pt += rc + 2 + 2 + 4;
+  if (pt+2 >= emsg)
+    return gpg_error (GPG_ERR_SERVER_FAILED);
+  pt += 2;  /* Skip rdlen */
+
+  cname = xtrymalloc (cnamesize);
+  if (!cname)
+    return gpg_error_from_syserror ();
+
+  rc = dn_expand (answer, emsg, pt, cname, cnamesize -1);
+  if (rc == -1)
+    {
+      xfree (cname);
+      return gpg_error (GPG_ERR_SERVER_FAILED);
+    }
+  *r_cname = xtryrealloc (cname, strlen (cname)+1);
+  if (!*r_cname)
+    {
+      err = gpg_error_from_syserror ();
+      xfree (cname);
+      return err;
+    }
+  return 0;
+
+#else /*!HAVE_SYSTEM_RESOLVER*/
+
+  (void)name;
+  (void)r_cname;
+  return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
+
+#endif /*!HAVE_SYSTEM_RESOLVER*/
+}
+
+
+gpg_error_t
+get_dns_cname (const char *name, char **r_cname)
+{
+  gpg_error_t err;
+
+  *r_cname = NULL;
+
+#ifdef USE_LIBDNS
+  if (!standard_resolver)
+    {
+      err = get_dns_cname_libdns (name, r_cname);
+      if (err && libdns_switch_port_p (err))
+        err = get_dns_cname_libdns (name, r_cname);
+      return err;
+    }
+#endif /*USE_LIBDNS*/
+
+  err = get_dns_cname_standard (name, r_cname);
+  if (opt_debug)
+    log_debug ("get_dns_cname(%s)%s%s\n", name,
+               err ? ": " : " -> ",
+               err ? gpg_strerror (err) : *r_cname);
+  return err;
+}
+
+
+/* Check whether the machine has any usable inet devices up and
+ * running.  We put this into dns because on Windows this is
+ * implemented using getaddrinfo and thus easiest done here.  */
+void
+check_inet_support (int *r_v4, int *r_v6)
+{
+  if (cached_inet_support.valid)
+    {
+      *r_v4 = cached_inet_support.v4;
+      *r_v6 = cached_inet_support.v6;
+      return;
+    }
+
+  *r_v4 = *r_v6 = 0;
+
+#ifdef HAVE_W32_SYSTEM
+  {
+    gpg_error_t err;
+    int ret;
+    struct addrinfo *aibuf = NULL;
+    struct addrinfo *ai;
+
+    ret = getaddrinfo ("..localmachine", NULL, NULL, &aibuf);
+    if (ret)
+      {
+        err = map_eai_to_gpg_error (ret);
+        log_error ("%s: getaddrinfo failed: %s\n",__func__, gpg_strerror (err));
+        aibuf = NULL;
+      }
+
+    for (ai = aibuf; ai; ai = ai->ai_next)
+      {
+        if (opt_debug)
+          {
+            log_debug ("%s:  family: %d\n", __func__, ai->ai_family);
+            if (ai->ai_family == AF_INET6 || ai->ai_family == AF_INET)
+              {
+                char buffer[46];
+                DWORD buflen;
+                buflen = sizeof buffer;
+                if (WSAAddressToString (ai->ai_addr, (DWORD)ai->ai_addrlen,
+                                        NULL, buffer, &buflen))
+                  log_debug ("%s: WSAAddressToString failed: ec=%u\n",
+                             __func__, (unsigned int)WSAGetLastError ());
+                else
+                  log_debug ("%s:     addr: %s\n", __func__, buffer);
+              }
+          }
+        if (ai->ai_family == AF_INET6)
+          {
+            struct sockaddr_in6 *v6addr = (struct sockaddr_in6 *)ai->ai_addr;
+            if (!IN6_IS_ADDR_LINKLOCAL (&v6addr->sin6_addr))
+              *r_v6 = 1;
+          }
+        else if (ai->ai_family == AF_INET)
+          {
+            *r_v4 = 1;
+          }
+      }
+
+    if (aibuf)
+      freeaddrinfo (aibuf);
+  }
+#else /*!HAVE_W32_SYSTEM*/
+  {
+    /* For now we assume that we have both protocols.  */
+    *r_v4 = *r_v6 = 1;
+  }
+#endif /*!HAVE_W32_SYSTEM*/
+
+  if (opt_verbose)
+    log_info ("detected interfaces:%s%s\n",
+              *r_v4? " IPv4":"", *r_v6? " IPv6":"");
+
+  cached_inet_support.valid = 1;
+  cached_inet_support.v4 = *r_v4;
+  cached_inet_support.v6 = *r_v6;
+}