add logic to handle SRV/DANE names (#3003 and 2526) in GNS resolver

[oweals/gnunet.git] / src / gns / gnunet-service-gns_resolver.c

diff --git a/src/gns/gnunet-service-gns_resolver.c b/src/gns/gnunet-service-gns_resolver.c
index 8e4de4b7d3805bd4f9401b0e991f25804abe434d..67f1902cd05c15290b1813b60aaefdbea5d192f8 100644 (file)
--- a/src/gns/gnunet-service-gns_resolver.c
+++ b/src/gns/gnunet-service-gns_resolver.c
@@ -23,12 +23,6 @@
  * @brief GNU Name System resolver logic
  * @author Martin Schanzenbach
  * @author Christian Grothoff
- *
- * TODO:
- * - GNS: handle special SRV names --- no delegation, direct lookup;
- *        can likely be done in 'resolver_lookup_get_next_label'. (#3003)
- * - revocation checks (use REVOCATION service!), (#3004)
- * - DNAME support (#3005)
  */
 #include "platform.h"
 #include "gnunet_util_lib.h"
@@ -365,7 +359,7 @@ struct GNS_ResolverHandle
   /**
    * Use only cache
    */
-  int only_cached;
+  enum GNUNET_GNS_LocalOptions options;
 
   /**
    * Desired type for the resolution.
@@ -601,7 +595,17 @@ memrchr (const void *s,
 
 /**
  * Get the next, rightmost label from the name that we are trying to resolve,
- * and update the resolution position accordingly.
+ * and update the resolution position accordingly.  Labels usually consist
+ * of up to 63 characters without a period ("."); however, we use a special
+ * convention to support SRV and TLSA records where the domain name
+ * includes an encoding for a service and protocol in the name.  The
+ * syntax (see RFC 2782) here is "_Service._Proto.Name" and in this
+ * special case we include the "_Service._Proto" in the rightmost label.
+ * Thus, for "_443._tcp.foo.bar" we first return the label "bar" and then
+ * the label "_443._tcp.foo".  The special case is detected by the
+ * presence of labels beginning with an underscore.  Whenever a label
+ * begins with an underscore, it is combined with the label to its right
+ * (and the "." is preserved).
  *
  * @param rh handle to the resolution operation to get the next label from
  * @return NULL if there are no more labels
@@ -615,7 +619,9 @@ resolver_lookup_get_next_label (struct GNS_ResolverHandle *rh)
 
   if (0 == rh->name_resolution_pos)
     return NULL;
-  dot = memrchr (rh->name, (int) '.', rh->name_resolution_pos);
+  dot = memrchr (rh->name,
+                 (int) '.',
+                 rh->name_resolution_pos);
   if (NULL == dot)
   {
     /* done, this was the last one */
@@ -630,6 +636,16 @@ resolver_lookup_get_next_label (struct GNS_ResolverHandle *rh)
     rp = dot + 1;
     rh->name_resolution_pos = dot - rh->name;
   }
+  /* merge labels starting with underscore with label on the right (SRV/DANE case) */
+  while ( (NULL != (dot = memrchr (rh->name,
+                                   (int) '.',
+                                   rh->name_resolution_pos))) &&
+          ('_' == dot[1]) )
+  {
+    len += rh->name_resolution_pos - (dot - rh->name) - 1;
+    rp = dot + 1;
+    rh->name_resolution_pos = dot - rh->name;
+  }
   return GNUNET_strndup (rp, len);
 }
 
@@ -1584,8 +1600,6 @@ handle_gns_resolution_result (void *cls,
          struct GNUNET_DNSPARSER_SrvRecord *srv;
 
          off = 0;
-         /* FIXME: passing rh->name here is is not necessarily what we want
-            (SRV support not finished) */
          srv = GNUNET_DNSPARSER_parse_srv (rh->name,
                                            rd[i].data,
                                            rd[i].data_size,
@@ -1779,7 +1793,7 @@ handle_gns_resolution_result (void *cls,
         g2dc->rh->proc = &handle_gns2dns_result;
         g2dc->rh->proc_cls = rh;
         g2dc->rh->record_type = GNUNET_GNSRECORD_TYPE_ANY;
-        g2dc->rh->only_cached = GNUNET_NO;
+        g2dc->rh->options = GNUNET_GNS_LO_DEFAULT;
         g2dc->rh->loop_limiter = rh->loop_limiter + 1;
         rh->g2dc = g2dc;
         start_resolver_lookup (g2dc->rh);
@@ -2011,7 +2025,9 @@ handle_namecache_block_response (void *cls,
 
   GNUNET_assert (NULL != rh->namecache_qe);
   rh->namecache_qe = NULL;
-  if ( (GNUNET_NO == rh->only_cached) &&
+  if ( ( (GNUNET_GNS_LO_DEFAULT == rh->options) ||
+        ( (GNUNET_GNS_LO_LOCAL_MASTER == rh->options) &&
+          (ac != rh->ac_head) ) ) &&
        ( (NULL == block) ||
         (0 == GNUNET_TIME_absolute_get_remaining (GNUNET_TIME_absolute_ntoh (block->expiration_time)).rel_value_us) ) )
   {
@@ -2303,7 +2319,7 @@ start_resolver_lookup (struct GNS_ResolverHandle *rh)
  * @param record_type the record type to look up
  * @param name the name to look up
  * @param shorten_key a private key for use with PSEU import (can be NULL)
- * @param only_cached #GNUNET_NO to only check locally not DHT for performance
+ * @param options local options to control local lookup
  * @param proc the processor to call on result
  * @param proc_cls the closure to pass to @a proc
  * @return handle to cancel operation
@@ -2313,7 +2329,7 @@ GNS_resolver_lookup (const struct GNUNET_CRYPTO_EcdsaPublicKey *zone,
                     uint32_t record_type,
                     const char *name,
                     const struct GNUNET_CRYPTO_EcdsaPrivateKey *shorten_key,
-                    int only_cached,
+                    enum GNUNET_GNS_LocalOptions options,
                     GNS_ResultProcessor proc, void *proc_cls)
 {
   struct GNS_ResolverHandle *rh;
@@ -2330,7 +2346,7 @@ GNS_resolver_lookup (const struct GNUNET_CRYPTO_EcdsaPublicKey *zone,
   rh->authority_zone = *zone;
   rh->proc = proc;
   rh->proc_cls = proc_cls;
-  rh->only_cached = only_cached;
+  rh->options = options;
   rh->record_type = record_type;
   rh->name = GNUNET_strdup (name);
   rh->name_resolution_pos = strlen (name);