Add randomized delay when forwarding txes from i2p/tor -> ipv4/6

1 files changed, 14 insertions, 4 deletions

diff --git a/src/cryptonote_protocol/cryptonote_protocol_handler.inl b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
index f8e032fde..ef3ea837d 100644
--- a/src/cryptonote_protocol/cryptonote_protocol_handler.inl
+++ b/src/cryptonote_protocol/cryptonote_protocol_handler.inl
@@ -927,7 +927,19 @@ namespace cryptonote
       return 1;
     }
 
-    relay_method tx_relay;
+    /* If the txes were received over i2p/tor, the default is to "forward"
+       with a randomized delay to further enhance the "white noise" behavior,
+       potentially making it harder for ISP-level spies to determine which
+       inbound link sent the tx. If the sender disabled "white noise" over
+       i2p/tor, then the sender is "fluffing" (to only outbound) i2p/tor
+       connections with the `dandelionpp_fluff` flag set. The receiver (hidden
+       service) will immediately fluff in that scenario (i.e. this assumes that a
+       sybil spy will be unable to link an IP to an i2p/tor connection). */
+
+    const epee::net_utils::zone zone = context.m_remote_address.get_zone();
+    relay_method tx_relay = zone == epee::net_utils::zone::public_ ?
+      relay_method::stem : relay_method::forward;
+
     std::vector<blobdata> stem_txs{};
     std::vector<blobdata> fluff_txs{};
     if (arg.dandelionpp_fluff)
@@ -936,10 +948,7 @@ namespace cryptonote
       fluff_txs.reserve(arg.txs.size());
     }
     else
-    {
-      tx_relay = relay_method::stem;
       stem_txs.reserve(arg.txs.size());
-    }
 
     for (auto& tx : arg.txs)
     {
@@ -962,6 +971,7 @@ namespace cryptonote
           fluff_txs.push_back(std::move(tx));
           break;
         default:
+        case relay_method::forward: // not supposed to happen here
         case relay_method::none:
           break;
       }