From 1dcc89cca9d3c45479b319444735a4881b5180db Mon Sep 17 00:00:00 2001
From: "Johan T. Halseth" <johanth@gmail.com>
Date: Mon, 15 Jan 2018 23:27:27 +0100
Subject: [PATCH] lnwallet/btcwallet: return concrete error type from
 PublishTransaction

---
 lnwallet/btcwallet/btcwallet.go | 85 ++++++++++++++++++++++++++++++++-
 1 file changed, 83 insertions(+), 2 deletions(-)

diff --git a/lnwallet/btcwallet/btcwallet.go b/lnwallet/btcwallet/btcwallet.go
index c6229edc..4c4f50f9 100644
--- a/lnwallet/btcwallet/btcwallet.go
+++ b/lnwallet/btcwallet/btcwallet.go
@@ -5,6 +5,7 @@ import (
 	"encoding/hex"
 	"fmt"
 	"math"
+	"strings"
 	"sync"
 	"time"
 
@@ -399,9 +400,89 @@ func (b *BtcWallet) ListUnspentWitness(minConfs int32) ([]*lnwallet.Utxo, error)
 }
 
 // PublishTransaction performs cursory validation (dust checks, etc), then
-// finally broadcasts the passed transaction to the Bitcoin network.
+// finally broadcasts the passed transaction to the Bitcoin network. If
+// publishing the transaction fails, an error describing the reason is
+// returned (currently ErrDoubleSpend). If the transaction is already
+// published to the network (either in the mempool or chain) no error
+// will be returned.
 func (b *BtcWallet) PublishTransaction(tx *wire.MsgTx) error {
-	return b.wallet.PublishTransaction(tx)
+	if err := b.wallet.PublishTransaction(tx); err != nil {
+		switch b.chain.(type) {
+		case *chain.RPCClient:
+			if strings.Contains(err.Error(), "already have") {
+				// Transaction was already in the mempool, do
+				// not treat as an error. We do this to mimic
+				// the behaviour of bitcoind, which will not
+				// return an error if a transaction in the
+				// mempool is sent again using the
+				// sendrawtransaction RPC call.
+				return nil
+			}
+			if strings.Contains(err.Error(), "already exists") {
+				// Transaction was already mined, we don't
+				// consider this an error.
+				return nil
+			}
+			if strings.Contains(err.Error(), "already spent") {
+				// Output was already spent.
+				return lnwallet.ErrDoubleSpend
+			}
+			if strings.Contains(err.Error(), "orphan transaction") {
+				// Transaction is spending either output that
+				// is missing or already spent.
+				return lnwallet.ErrDoubleSpend
+			}
+
+		case *chain.BitcoindClient:
+			if strings.Contains(err.Error(), "txn-already-in-mempool") {
+				// Transaction in mempool, treat as non-error.
+				return nil
+			}
+			if strings.Contains(err.Error(), "txn-already-known") {
+				// Transaction in mempool, treat as non-error.
+				return nil
+			}
+			if strings.Contains(err.Error(), "already in block") {
+				// Transaction was already mined, we don't
+				// consider this an error.
+				return nil
+			}
+			if strings.Contains(err.Error(), "txn-mempool-conflict") {
+				// Output was spent by other transaction
+				// already in the mempool.
+				return lnwallet.ErrDoubleSpend
+			}
+			if strings.Contains(err.Error(), "insufficient fee") {
+				// RBF enabled transaction did not have enough fee.
+				return lnwallet.ErrDoubleSpend
+			}
+			if strings.Contains(err.Error(), "Missing inputs") {
+				// Transaction is spending either output that
+				// is missing or already spent.
+				return lnwallet.ErrDoubleSpend
+			}
+
+		case *chain.NeutrinoClient:
+			if strings.Contains(err.Error(), "already have") {
+				// Transaction was already in the mempool, do
+				// not treat as an error.
+				return nil
+			}
+			if strings.Contains(err.Error(), "already exists") {
+				// Transaction was already mined, we don't
+				// consider this an error.
+				return nil
+			}
+			if strings.Contains(err.Error(), "already spent") {
+				// Output was already spent.
+				return lnwallet.ErrDoubleSpend
+			}
+
+		default:
+		}
+		return err
+	}
+	return nil
 }
 
 // extractBalanceDelta extracts the net balance delta from the PoV of the