hs-v3: Silence some logging for client authorization

If a tor client gets a descriptor that it can't decrypt, chances are that the
onion requires client authorization.

If a tor client is configured with client authorization for an onion but
decryption fails, it means that the configured keys aren't working anymore.

In both cases, we'll log notice the former and log warn the latter and the
rest of the decryption errors are now at info level.

Two logs statement have been removed because it was redundant and printing the
fetched descriptor in the logs when 80% of it is encrypted wat not helping.

Fixes #27550

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/ticket27550

@@ -0,0 +1,5 @@
+  o Minor bugfixes (hidden service v3):
+    - Don't warn so loudly when tor is unable to decode a descriptor. This can
+      now happen as a normal use case if a client gets a descriptor with
+      client authorization but the client is not authorized. Fixes bug 27550;
+      bugfix on 0.3.5.1-alpha.

src/or/directory.c

@@ -3091,7 +3091,7 @@ handle_response_fetch_hsdesc_v3(dir_connection_t *conn,
   case 200:
     /* We got something: Try storing it in the cache. */
     if (hs_cache_store_as_client(body, &conn->hs_ident->identity_pk) < 0) {
-      log_warn(LD_REND, "Failed to store hidden service descriptor");
+      log_info(LD_REND, "Failed to store hidden service descriptor");
       /* Fire control port FAILED event. */
       hs_control_desc_event_failed(conn->hs_ident, conn->identity_digest,
                                    "BAD_DESC");

src/or/hs_client.c

@@ -1225,10 +1225,6 @@ hs_client_decode_descriptor(const char *desc_str,
   ret = hs_desc_decode_descriptor(desc_str, subcredential, desc);
   memwipe(subcredential, 0, sizeof(subcredential));
   if (ret < 0) {
-    log_warn(LD_GENERAL, "Could not parse received descriptor as client.");
-    if (get_options()->SafeLogging_ == SAFELOG_SCRUB_NONE) {
-      log_warn(LD_GENERAL, "%s", escaped(desc_str));
-    }
     goto err;
   }
 

src/or/hs_descriptor.c

@@ -1361,7 +1361,7 @@ decrypt_desc_layer,(const hs_descriptor_t *desc,
    * This is a critical check that is making sure the computed MAC matches the
    * one in the descriptor. */
   if (!tor_memeq(our_mac, desc_mac, sizeof(our_mac))) {
-    log_warn(LD_REND, "Encrypted service descriptor MAC check failed");
+    log_info(LD_REND, "Encrypted service descriptor MAC check failed");
     goto err;
   }
 
@@ -1544,7 +1544,6 @@ desc_decrypt_all(const hs_descriptor_t *desc, char **decrypted_out)
                                         superencrypted_len,
                                         &encrypted_blob);
   if (!encrypted_len) {
-    log_warn(LD_REND, "Decrypting encrypted desc failed.");
     goto err;
   }
   tor_assert(encrypted_blob);
@@ -2046,7 +2045,11 @@ desc_decode_encrypted_v3(const hs_descriptor_t *desc,
    * in the descriptor as a blob of bytes. */
   message_len = desc_decrypt_all(desc, &message);
   if (!message_len) {
-    log_warn(LD_REND, "Service descriptor decryption failed.");
+    /* Inform at notice level that the onion address requested can't be
+     * reached without client authorization most likely. */
+    log_notice(LD_REND, "Fail to decrypt descriptor for requested onion "
+                        "address. It is likely requiring client "
+                        "authorization.");
     goto err;
   }
   tor_assert(message);