mixing: Improve orphan handling.

internal/netsync/manager.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2013-2016 The btcsuite developers
-// Copyright (c) 2015-2025 The Decred developers
+// Copyright (c) 2015-2026 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -1056,7 +1056,8 @@ func (m *SyncManager) OnMixMsg(peer *Peer, msg mixing.Message) ([]mixing.Message
 		return nil, nil
 	}
 
-	accepted, err := m.cfg.MixPool.AcceptMessage(msg)
+	source := mixpool.Uint64Source(peer.ID())
+	accepted, err := m.cfg.MixPool.AcceptMessage(msg, source)
 
 	// Remove message from request maps. Either the mixpool already knows
 	// about it and as such we shouldn't have any more instances of trying

internal/rpcserver/interface.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2019-2025 The Decred developers
+// Copyright (c) 2019-2026 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -20,6 +20,7 @@ import (
 	"github.com/decred/dcrd/internal/mining"
 	"github.com/decred/dcrd/math/uint256"
 	"github.com/decred/dcrd/mixing"
+	"github.com/decred/dcrd/mixing/mixpool"
 	"github.com/decred/dcrd/peer/v3"
 	"github.com/decred/dcrd/rpc/jsonrpc/types/v4"
 	"github.com/decred/dcrd/txscript/v4/stdaddr"
@@ -200,9 +201,9 @@ type SyncManager interface {
 	// This method may report a false positive, but never a false negative.
 	RecentlyConfirmedTxn(hash *chainhash.Hash) bool
 
-	// SubmitMixMessage submits the mixing message to the network after
-	// processing it locally.
-	SubmitMixMessage(msg mixing.Message) error
+	// AcceptMixMessage attempts to accept a mixing message to the local mixing
+	// pool.
+	AcceptMixMessage(msg mixing.Message, src mixpool.Source) error
 }
 
 // UtxoEntry represents a utxo entry for use with the RPC server.

internal/rpcserver/rpcserver.go

@@ -1,5 +1,5 @@
 // Copyright (c) 2013-2016 The btcsuite developers
-// Copyright (c) 2015-2025 The Decred developers
+// Copyright (c) 2015-2026 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -50,6 +50,7 @@ import (
 	"github.com/decred/dcrd/internal/mining/cpuminer"
 	"github.com/decred/dcrd/internal/version"
 	"github.com/decred/dcrd/mixing"
+	"github.com/decred/dcrd/mixing/mixpool"
 	"github.com/decred/dcrd/rpc/jsonrpc/types/v4"
 	"github.com/decred/dcrd/txscript/v4"
 	"github.com/decred/dcrd/txscript/v4/stdaddr"
@@ -4348,7 +4349,8 @@ func handleSendRawMixMessage(_ context.Context, s *Server, cmd interface{}) (int
 	msg.WriteHash(s.blake256Hasher)
 	s.blake256HaserMu.Unlock()
 
-	err = s.cfg.SyncMgr.SubmitMixMessage(msg)
+	// Use 0 for the source to represent the local node.
+	err = s.cfg.SyncMgr.AcceptMixMessage(msg, mixpool.ZeroSource)
 	if err != nil {
 		// XXX: consider a better error code/function
 		str := fmt.Sprintf("Rejected mix message: %s", err)

internal/rpcserver/rpcserverhandlers_test.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2020-2025 The Decred developers
+// Copyright (c) 2020-2026 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -44,6 +44,7 @@ import (
 	"github.com/decred/dcrd/internal/version"
 	"github.com/decred/dcrd/math/uint256"
 	"github.com/decred/dcrd/mixing"
+	"github.com/decred/dcrd/mixing/mixpool"
 	"github.com/decred/dcrd/peer/v3"
 	"github.com/decred/dcrd/rpc/jsonrpc/types/v4"
 	"github.com/decred/dcrd/txscript/v4"
@@ -572,7 +573,7 @@ func (c *testAddrManager) LocalAddresses() []addrmgr.LocalAddr {
 type testSyncManager struct {
 	isCurrent             bool
 	submitBlockErr        error
-	submitMixErr          error
+	acceptMixErr          error
 	syncPeerID            int32
 	syncHeight            int64
 	processTransaction    []*dcrutil.Tx
@@ -592,10 +593,6 @@ func (s *testSyncManager) SubmitBlock(block *dcrutil.Block) error {
 	return s.submitBlockErr
 }
 
-func (s *testSyncManager) SubmitMixMessage(msg mixing.Message) error {
-	return s.submitMixErr
-}
-
 // SyncPeer returns a mocked id of the current peer being synced with.
 func (s *testSyncManager) SyncPeerID() int32 {
 	return s.syncPeerID
@@ -619,6 +616,12 @@ func (s *testSyncManager) RecentlyConfirmedTxn(hash *chainhash.Hash) bool {
 	return s.recentlyConfirmedTxn
 }
 
+// AcceptMixMessage provides a mock implementation for attempting to accept a
+// mixing message to the local mixing pool.
+func (s *testSyncManager) AcceptMixMessage(msg mixing.Message, src mixpool.Source) error {
+	return s.acceptMixErr
+}
+
 // testExistsAddresser provides a mock exists addresser by implementing the
 // ExistsAddresser interface.
 type testExistsAddresser struct {

mixing/mixclient/client_test.go

@@ -1,4 +1,4 @@
-// Copyright (c) 2024 The Decred developers
+// Copyright (c) 2024-2026 The Decred developers
 // Use of this source code is governed by an ISC
 // license that can be found in the LICENSE file.
 
@@ -114,7 +114,7 @@ func (w *testWallet) SignInput(tx *wire.MsgTx, index int, prevScript []byte) err
 }
 
 func (w *testWallet) SubmitMixMessage(ctx context.Context, msg mixing.Message) error {
-	_, err := w.mixpool.AcceptMessage(msg)
+	_, err := w.mixpool.AcceptMessage(msg, mixpool.ZeroSource)
 	return err
 }