From c8130df1d9dcc504244a49cbb12aa4c2848e5de2 Mon Sep 17 00:00:00 2001
From: Zsolt Felfoldi <zsfelfoldi@gmail.com>
Date: Tue, 6 Dec 2016 06:16:53 +0100
Subject: [PATCH] les: using random request IDs

---
 les/fetcher.go |  2 +-
 les/handler.go |  4 ++--
 les/odr.go     | 15 +++++++--------
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/les/fetcher.go b/les/fetcher.go
index 0c8be9e2a2..00cb31dfb9 100644
--- a/les/fetcher.go
+++ b/les/fetcher.go
@@ -350,7 +350,7 @@ func (f *lightFetcher) request(p *peer, n *fetcherTreeNode, amount uint64) (uint
 		return 0, false
 	}
 
-	reqID := f.odr.getNextReqID()
+	reqID := getNextReqID()
 	n.requested = true
 	cost := p.GetRequestCost(GetBlockHeadersMsg, int(amount))
 	p.fcServer.SendRequest(reqID, cost)
diff --git a/les/handler.go b/les/handler.go
index 4535aaeb9f..3fc80e19a1 100644
--- a/les/handler.go
+++ b/les/handler.go
@@ -338,13 +338,13 @@ func (pm *ProtocolManager) handle(p *peer) error {
 	glog.V(logger.Debug).Infof("LES: register peer %v", p.id)
 	if pm.lightSync {
 		requestHeadersByHash := func(origin common.Hash, amount int, skip int, reverse bool) error {
-			reqID := pm.odr.getNextReqID()
+			reqID := getNextReqID()
 			cost := p.GetRequestCost(GetBlockHeadersMsg, amount)
 			p.fcServer.SendRequest(reqID, cost)
 			return p.RequestHeadersByHash(reqID, cost, origin, amount, skip, reverse)
 		}
 		requestHeadersByNumber := func(origin uint64, amount int, skip int, reverse bool) error {
-			reqID := pm.odr.getNextReqID()
+			reqID := getNextReqID()
 			cost := p.GetRequestCost(GetBlockHeadersMsg, amount)
 			p.fcServer.SendRequest(reqID, cost)
 			return p.RequestHeadersByNumber(reqID, cost, origin, amount, skip, reverse)
diff --git a/les/odr.go b/les/odr.go
index 10ef928df3..4bfbdcb4d0 100644
--- a/les/odr.go
+++ b/les/odr.go
@@ -17,6 +17,8 @@
 package les
 
 import (
+	"crypto/rand"
+	"encoding/binary"
 	"sync"
 	"time"
 
@@ -50,7 +52,6 @@ type LesOdr struct {
 	mlock, clock sync.Mutex
 	sentReqs     map[uint64]*sentReq
 	serverPool   odrPeerSelector
-	lastReqID    uint64
 }
 
 func NewLesOdr(db ethdb.Database) *LesOdr {
@@ -167,7 +168,7 @@ func (self *LesOdr) networkRequest(ctx context.Context, lreq LesOdrRequest) erro
 		sentTo:   make(map[*peer]chan struct{}),
 		answered: answered, // reply delivered by any peer
 	}
-	reqID := self.getNextReqID()
+	reqID := getNextReqID()
 	self.mlock.Lock()
 	self.sentReqs[reqID] = req
 	self.mlock.Unlock()
@@ -236,10 +237,8 @@ func (self *LesOdr) Retrieve(ctx context.Context, req light.OdrRequest) (err err
 	return
 }
 
-func (self *LesOdr) getNextReqID() uint64 {
-	self.clock.Lock()
-	defer self.clock.Unlock()
-
-	self.lastReqID++
-	return self.lastReqID
+func getNextReqID() uint64 {
+	var rnd [8]byte
+	rand.Read(rnd[:])
+	return binary.BigEndian.Uint64(rnd[:])
 }