From 89f6d045c8e3dacbfbb369a3ac89c0c33de22b4c Mon Sep 17 00:00:00 2001
From: mtg0001 <106211915+mtg0001@users.noreply.github.com>
Date: Sun, 2 Aug 2026 10:56:50 -0300
Subject: Keep HD change recoverable and bound message stalls (#109)

Change from an HD wallet now goes to a newly derived phrase-backed key instead of reusing a spent input's key. Reusing an input key silently moved value back to a key the phrase cannot reproduce; if derivation fails the transaction is refused rather than creating unrecoverable change. Legacy wallets with no seed keep the 0.1.0 behaviour. Restore also scans past the pre-generated key-pool window before treating an empty batch as the end.

The message parser no longer consumes a header it cannot complete: it reads from a copy, so the O(n) reinsert and the 100 ms sleep inside the shared message thread are gone, and a peer that sits on an incomplete payload is disconnected after two minutes. The wire cap drops from 256 MB to MAX_SIZE. New net-message self-test covers complete, incomplete, stale and oversized headers.

Verified here: clean rebuild, all self-tests pass, lock order checked (no path takes cs_keyPool before cs_mapWallet), and a node built from this branch synced from genesis to the chain tip on the live network with zero rejections.
---
 src/net.h | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

(limited to 'src/net.h')

diff --git a/src/net.h b/src/net.h
index 1c0c24e..37f335e 100644
--- a/src/net.h
+++ b/src/net.h
@@ -67,6 +67,13 @@ static const int          BTF_RECV_TIMEOUT_SECS    = 30 * 60;
 static const int          BTF_SEND_STALL_SECS      = 10 * 60;
 static const int          BTF_HANDSHAKE_GRACE_SECS = 60;
 
+// A serialized object cannot be larger than MAX_SIZE, so no valid network
+// message needs the old 256 MB header allowance. Keep the wire cap aligned with
+// what the deserializer can accept and bound how long one peer may sit on a
+// partial payload after a complete header has arrived.
+static const unsigned int MAX_PROTOCOL_MESSAGE_SIZE = MAX_SIZE;
+static const int          BTF_INCOMPLETE_MESSAGE_TIMEOUT_SECS = 2 * 60;
+
 // Ceiling on simultaneous connections.
 //
 // ThreadSocketHandler watches every peer through one select(), and select()
@@ -225,7 +232,7 @@ public:
         }
 
         // Message size
-        if (nMessageSize > 0x10000000)
+        if (nMessageSize > MAX_PROTOCOL_MESSAGE_SIZE)
         {
             if (LogAcceptsCategory("net")) printf("CMessageHeader::IsValid() : nMessageSize too large %u\n", nMessageSize);
             return false;
@@ -596,6 +603,9 @@ public:
     int64 nLastSend;
     int64 nLastRecv;
     int64 nLastSendEmpty;
+    int64 nIncompleteMessageStart;
+    unsigned int nIncompleteMessageSize;
+    string strIncompleteMessageCommand;
 
     // Height this peer announced in its version message, or -1 if it sent a
     // version message that predates the field. Knowing how far along everyone
@@ -626,6 +636,9 @@ public:
         nLastSend = 0;
         nLastRecv = 0;
         nLastSendEmpty = GetTime();
+        nIncompleteMessageStart = 0;
+        nIncompleteMessageSize = 0;
+        strIncompleteMessageCommand.clear();
         nStartingHeight = -1;
         vfSubscribe.assign(256, false);
 
-- 
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