lock on payment hash

intercept.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"encoding/hex"
 	"fmt"
 	"log"
 	"math/big"
@@ -12,6 +13,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/routing/route"
+	"golang.org/x/sync/singleflight"
 )
 
 type interceptAction int
@@ -30,6 +32,8 @@ var (
 	FAILURE_INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS interceptFailureCode = 0x4015
 )
 
+var payHashGroup singleflight.Group
+
 type interceptResult struct {
 	action       interceptAction
 	failureCode  interceptFailureCode
@@ -40,12 +44,14 @@ type interceptResult struct {
 }
 
 func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingExpiry uint32) interceptResult {
+	reqPaymentHashStr := hex.EncodeToString(reqPaymentHash)
+	resp, _, _ := payHashGroup.Do(reqPaymentHashStr, func() (interface{}, error) {
 		paymentHash, paymentSecret, destination, incomingAmountMsat, outgoingAmountMsat, channelPoint, err := paymentInfo(reqPaymentHash)
 		if err != nil {
 			log.Printf("paymentInfo(%x) error: %v", reqPaymentHash, err)
 			return interceptResult{
 				action: INTERCEPT_FAIL_HTLC,
-		}
+			}, nil
 		}
 		log.Printf("paymentHash:%x\npaymentSecret:%x\ndestination:%x\nincomingAmountMsat:%v\noutgoingAmountMsat:%v\n\n",
 			paymentHash, paymentSecret, destination, incomingAmountMsat, outgoingAmountMsat)
@@ -58,7 +64,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 					if err != nil {
 						return interceptResult{
 							action: INTERCEPT_FAIL_HTLC,
-					}
+						}, nil
 					}
 				} else { //probing
 					failureCode := FAILURE_TEMPORARY_CHANNEL_FAILURE
@@ -70,7 +76,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 					return interceptResult{
 						action:      INTERCEPT_FAIL_HTLC_WITH_CODE,
 						failureCode: failureCode,
-				}
+					}, nil
 				}
 			}
 
@@ -79,7 +85,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				log.Printf("btcec.ParsePubKey(%x): %v", destination, err)
 				return interceptResult{
 					action: INTERCEPT_FAIL_HTLC,
-			}
+				}, nil
 			}
 
 			sessionKey, err := btcec.NewPrivateKey()
@@ -87,7 +93,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				log.Printf("btcec.NewPrivateKey(): %v", err)
 				return interceptResult{
 					action: INTERCEPT_FAIL_HTLC,
-			}
+				}, nil
 			}
 
 			var bigProd, bigAmt big.Int
@@ -108,7 +114,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				log.Printf("hop.PackHopPayload(): %v", err)
 				return interceptResult{
 					action: INTERCEPT_FAIL_HTLC,
-			}
+				}, nil
 			}
 
 			payload, err := sphinx.NewHopPayload(nil, b.Bytes())
@@ -116,7 +122,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				log.Printf("sphinx.NewHopPayload(): %v", err)
 				return interceptResult{
 					action: INTERCEPT_FAIL_HTLC,
-			}
+				}, nil
 			}
 
 			var sphinxPath sphinx.PaymentPath
@@ -132,7 +138,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				log.Printf("sphinx.NewOnionPacket(): %v", err)
 				return interceptResult{
 					action: INTERCEPT_FAIL_HTLC,
-			}
+				}, nil
 			}
 			var onionBlob bytes.Buffer
 			err = sphinxPacket.Encode(&onionBlob)
@@ -140,7 +146,7 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				log.Printf("sphinxPacket.Encode(): %v", err)
 				return interceptResult{
 					action: INTERCEPT_FAIL_HTLC,
-			}
+				}, nil
 			}
 
 			return interceptResult{
@@ -149,13 +155,17 @@ func intercept(reqPaymentHash []byte, reqOutgoingAmountMsat uint64, reqOutgoingE
 				channelPoint: channelPoint,
 				amountMsat:   uint64(amt),
 				onionBlob:    onionBlob.Bytes(),
-		}
+			}, nil
 		} else {
 			return interceptResult{
 				action: INTERCEPT_RESUME,
+			}, nil
 		}
-	}
+	})
+
+	return resp.(interceptResult)
 }
+
 func checkPayment(incomingAmountMsat, outgoingAmountMsat int64) error {
 	fees := incomingAmountMsat * channelFeePermyriad / 10_000 / 1_000 * 1_000
 	if fees < channelMinimumFeeMsat {