dirmngr: New option --nameserver.

* dirmngr/dirmngr.c (oNameServer): New.
(opts): Add --nameserver.
(parse_rereadable_options): Act upon oNameServer.
* dirmngr/dns-stuff.c (DEFAULT_NAMESERVER): New.
(tor_nameserver): New.
(set_dns_nameserver): New.
(my_adns_init): Make name server configurable.

Signed-off-by: Werner Koch <wk@gnupg.org>

dirmngr/dirmngr.c

@@ -68,6 +68,7 @@
 #endif
 #include "../common/init.h"
 #include "gc-opt-flags.h"
+#include "dns-stuff.h"
 
 /* The plain Windows version uses the windows service system.  For
    example to start the service you may use "sc start dirmngr".
@@ -142,6 +143,7 @@ enum cmd_and_opt_values {
   oIgnoreCertExtension,
   oUseTor,
   oKeyServer,
+  oNameServer,
   aTest
 };
 
@@ -214,6 +216,7 @@ static ARGPARSE_OPTS opts[] = {
   ARGPARSE_s_i (oMaxReplies, "max-replies",
                 N_("|N|do not return more than N items in one query")),
 
+  ARGPARSE_s_s (oNameServer, "nameserver", "@"),
   ARGPARSE_s_s (oKeyServer, "keyserver", "@"),
   ARGPARSE_s_s (oHkpCaCert, "hkp-cacert",
                 N_("|FILE|use the CA certificates in FILE for HKP over TLS")),
@@ -623,6 +626,10 @@ parse_rereadable_options (ARGPARSE_ARGS *pargs, int reread)
       opt.keyserver = *pargs->r.ret_str? xtrystrdup (pargs->r.ret_str) : NULL;
       break;
 
+    case oNameServer:
+      set_dns_nameserver (pargs->r.ret_str);
+      break;
+
     default:
       return 0; /* Not handled. */
     }

dirmngr/dns-stuff.c

@@ -82,9 +82,18 @@
 /* ADNS has no support for CERT yet. */
 #define my_adns_r_cert 37
 
+
+/* The default nameserver used with ADNS in Tor mode.  */
+#define DEFAULT_NAMESERVER "8.8.8.8"
+
+
 /* 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];
+
 /* A string to hold the credentials presented to Tor.  */
 #ifdef USE_ADNS
 static char tor_credentials[50];
@@ -114,6 +123,19 @@ enable_dns_tormode (int new_circuit)
   return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
 }
 
+
+/* 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;
+}
+
+
 /* Free an addressinfo linked list as returned by resolve_dns_name.  */
 void
 free_dns_addrinfo (dns_addrinfo_t ai)
@@ -167,14 +189,17 @@ my_adns_init (adns_state *r_state)
     {
       char *cfgstr;
 
+      if (!*tor_nameserver)
+        set_dns_nameserver (NULL);
+
       cfgstr = xtryasprintf ("nameserver %s\n"
                              "options adns_tormode adns_sockscred:%s",
-                             "8.8.8.8", tor_credentials);
+                             tor_nameserver, tor_credentials);
       if (!cfgstr)
         err = gpg_error_from_syserror ();
       else
         {
-          ret = adns_init_strcfg (r_state, adns_if_noerrprint, NULL, cfgstr);
+          ret = adns_init_strcfg (r_state, adns_if_debug /*adns_if_noerrprint*/, NULL, cfgstr);
           if (ret)
             err = gpg_error_from_errno (ret);
           xfree (cfgstr);

dirmngr/dns-stuff.h

@@ -96,6 +96,12 @@ struct srventry
    possibe.  Return 0 on success.  */
 gpg_error_t enable_dns_tormode (int new_circuit);
 
+/* 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);
+
+
 void free_dns_addrinfo (dns_addrinfo_t ai);
 
 /* Function similar to getaddrinfo.  */

doc/dirmngr.texi

@@ -244,11 +244,11 @@ this still leaks the DNS queries; e.g. to lookup the hosts in a
 keyserver pool.  Certain other features are disabled if this mode is
 active.
 
-@item --keyserver @code{name}
+@item --keyserver @var{name}
 @opindex keyserver
-Use @code{name} as your keyserver.  This is the server that @command{gpg}
+Use @var{name} as your keyserver.  This is the server that @command{gpg}
 communicates with to receive keys, send keys, and search for
-keys.  The format of the @code{name} is a URI:
+keys.  The format of the @var{name} is a URI:
 `scheme:[//]keyservername[:port]' The scheme is the type of keyserver:
 "hkp" for the HTTP (or compatible) keyservers, "ldap" for the LDAP
 keyservers, or "mailto" for the Graff email keyserver. Note that your
@@ -263,6 +263,16 @@ need to send keys to more than one server. The keyserver
 @code{hkp://keys.gnupg.net} uses round robin DNS to give a different
 keyserver each time you use it.
 
+
+@item --nameserver @var{ipaddr}
+@opindex nameserver
+In ``Tor mode'' Dirmngr uses a public resolver via Tor to resolve DNS
+names.  If the default public resolver, which is @code{8.8.8.8}, shall
+not be used a different one can be given using this option.  Note that
+a numerical IP address must be given (IPv6 or IPv4) and that no error
+checking is done for @var{ipaddr}.  DNS queries in Tor mode do only
+work if GnuPG as been build with ADNS support.
+
 @item --disable-ldap
 @opindex disable-ldap
 Entirely disables the use of LDAP.