From 900d7f6c075fd78e63503f31d267dbc16b3983d9 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter@wuille.net>
Date: Wed, 22 Jul 2020 17:19:43 -0700
Subject: [PATCH] p2p: enable fetching of orphans from wtxid peers

Based on a commit by Anthony Towns.
---
 src/net_processing.cpp | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 5f8a73cece..36508aa099 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -2647,7 +2647,9 @@ void ProcessMessage(
             if (interruptMsgProc)
                 return;
 
-            // ignore INVs that don't match wtxidrelay setting
+            // Ignore INVs that don't match wtxidrelay setting.
+            // Note that orphan parent fetching always uses MSG_TX GETDATAs regardless of the wtxidrelay setting.
+            // This is fine as no INV messages are involved in that process.
             if (State(pfrom.GetId())->m_wtxid_relay) {
                 if (inv.IsMsgTx()) continue;
             } else {
@@ -2931,9 +2933,11 @@ void ProcessMessage(
 
         TxValidationState state;
 
-        nodestate->m_tx_download.m_tx_announced.erase(hash);
-        nodestate->m_tx_download.m_tx_in_flight.erase(hash);
-        EraseTxRequest(hash);
+        for (uint256 hash : {txid, wtxid}) {
+            nodestate->m_tx_download.m_tx_announced.erase(hash);
+            nodestate->m_tx_download.m_tx_in_flight.erase(hash);
+            EraseTxRequest(hash);
+        }
 
         std::list<CTransactionRef> lRemovedTxn;
 
@@ -2985,17 +2989,15 @@ void ProcessMessage(
                 uint32_t nFetchFlags = GetFetchFlags(pfrom);
                 const auto current_time = GetTime<std::chrono::microseconds>();
 
-                if (!State(pfrom.GetId())->m_wtxid_relay) {
-                    for (const CTxIn& txin : tx.vin) {
-                        // Here, we only have the txid (and not wtxid) of the
-                        // inputs, so we only request parents from
-                        // non-wtxid-relay peers.
-                        // Eventually we should replace this with an improved
-                        // protocol for getting all unconfirmed parents.
-                        CInv _inv(MSG_TX | nFetchFlags, txin.prevout.hash);
-                        pfrom.AddKnownTx(txin.prevout.hash);
-                        if (!AlreadyHave(_inv, mempool)) RequestTx(State(pfrom.GetId()), ToGenTxid(_inv), current_time);
-                    }
+                for (const CTxIn& txin : tx.vin) {
+                    // Here, we only have the txid (and not wtxid) of the
+                    // inputs, so we only request in txid mode, even for
+                    // wtxidrelay peers.
+                    // Eventually we should replace this with an improved
+                    // protocol for getting all unconfirmed parents.
+                    CInv _inv(MSG_TX | nFetchFlags, txin.prevout.hash);
+                    pfrom.AddKnownTx(txin.prevout.hash);
+                    if (!AlreadyHave(_inv, mempool)) RequestTx(State(pfrom.GetId()), ToGenTxid(_inv), current_time);
                 }
                 AddOrphanTx(ptx, pfrom.GetId());