Refactor HS descriptor fetch to support descriptor ID

Big refactor of the HS client descriptor fetch functionnality. This allows
to fetch an HS descriptor using only a descriptor ID. Furthermore, it's also
possible to provide a list of HSDir(s) now that are used instead of the
automatically choosen one.

The approach taken was to add a descriptor_id field to the rend_data_t
structure so it can be used, if available, by the HS client. The onion
address field however has priority over it that is if both are set, the
onion address is used to fetch the descriptor.

A new public function is introduced called rend_client_fetch_v2_desc(...)
that does NOT lookup the client cache before fetching and can take a list of
HSDirs as a parameter.

The HSFETCH control command now uses this new function thus making it work
and final.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/or/rendcommon.c b/src/or/rendcommon.c
index 3fea07f52a..3d9cc23af4 100644
--- a/src/or/rendcommon.c
+++ b/src/or/rendcommon.c
@@ -1174,6 +1174,9 @@ rend_cache_store_v2_desc_as_client(const char *desc,
   tor_assert(desc);
   tor_assert(desc_id_base32);
   memset(want_desc_id, 0, sizeof(want_desc_id));
+  if (entry) {
+    *entry = NULL;
+  }
   if (base32_decode(want_desc_id, sizeof(want_desc_id),
                     desc_id_base32, strlen(desc_id_base32)) != 0) {
     log_warn(LD_BUG, "Couldn't decode base32 %s for descriptor id.",
@@ -1192,7 +1195,8 @@ rend_cache_store_v2_desc_as_client(const char *desc,
     log_warn(LD_REND, "Couldn't compute service ID.");
     goto err;
   }
-  if (strcmp(rend_query->onion_address, service_id)) {
+  if (rend_query->onion_address[0] != '\0' &&
+      strcmp(rend_query->onion_address, service_id)) {
     log_warn(LD_REND, "Received service descriptor for service ID %s; "
              "expected descriptor for service ID %s.",
              service_id, safe_str(rend_query->onion_address));
@@ -1239,7 +1243,7 @@ rend_cache_store_v2_desc_as_client(const char *desc,
                "service descriptor for %s. This is probably a (misguided) "
                "attempt to improve reliability, but it could also be an "
                "attempt to do a guard enumeration attack. Rejecting.",
-               safe_str_client(rend_query->onion_address));
+               safe_str_client(service_id));
 
       goto err;
     }