From be4ca2972d3c8493465d7e2c9c09d4996137251a Mon Sep 17 00:00:00 2001
From: vyzo <vyzo@hackzen.org>
Date: Tue, 15 Jan 2019 16:07:58 +0200
Subject: [PATCH] implement peer blacklist

---
 pubsub.go | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/pubsub.go b/pubsub.go
index e78b4bcc..4ca35121 100644
--- a/pubsub.go
+++ b/pubsub.go
@@ -94,6 +94,10 @@ type PubSub struct {
 	// eval thunk in event loop
 	eval chan func()
 
+	// peer blacklist
+	blacklist     map[peer.ID]struct{}
+	blacklistPeer chan peer.ID
+
 	peers        map[peer.ID]chan *RPC
 	seenMessages *timecache.TimeCache
 
@@ -175,6 +179,8 @@ func NewPubSub(ctx context.Context, h host.Host, rt PubSubRouter, opts ...Option
 		topics:           make(map[string]map[peer.ID]struct{}),
 		peers:            make(map[peer.ID]chan *RPC),
 		topicVals:        make(map[string]*topicVal),
+		blacklist:        make(map[peer.ID]struct{}),
+		blacklistPeer:    make(chan peer.ID),
 		seenMessages:     timecache.NewTimeCache(time.Second * 120),
 		counter:          uint64(time.Now().UnixNano()),
 	}
@@ -370,6 +376,10 @@ func (p *PubSub) processLoop(ctx context.Context) {
 		case thunk := <-p.eval:
 			thunk()
 
+		case pid := <-p.blacklistPeer:
+			log.Infof("Blacklisting peer %s", pid)
+			p.blacklist[pid] = struct{}{}
+
 		case <-ctx.Done():
 			log.Info("pubsub processloop shutting down")
 			return
@@ -563,6 +573,12 @@ func msgID(pmsg *pb.Message) string {
 
 // pushMsg pushes a message performing validation as necessary
 func (p *PubSub) pushMsg(vals []*topicVal, src peer.ID, msg *Message) {
+	// reject messages from blacklisted peers
+	if _, ok := p.blacklist[src]; ok {
+		log.Warningf("dropping message from blacklisted peer %s", src)
+		return
+	}
+
 	// reject unsigned messages when strict before we even process the id
 	if p.signStrict && msg.Signature == nil {
 		log.Debugf("dropping unsigned message from %s", src)
@@ -817,6 +833,11 @@ func (p *PubSub) ListPeers(topic string) []peer.ID {
 	return <-out
 }
 
+// BlacklistPeer blacklists a peer; all messages from this peer will be unconditionally dropped.
+func (p *PubSub) BlacklistPeer(pid peer.ID) {
+	p.blacklistPeer <- pid
+}
+
 // per topic validators
 type addValReq struct {
 	topic    string