From 1f7917589822d4327147949c610fad3979819ab3 Mon Sep 17 00:00:00 2001
From: Maran <maran.hidskes@gmail.com>
Date: Wed, 18 Jun 2014 13:06:48 +0200
Subject: [PATCH] Reworked peers to check for public key duplication and adding
 peers to peerlist only after the handshake has come in

---
 ethereum.go | 14 ++++----------
 peer.go     | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/ethereum.go b/ethereum.go
index d9281cd574..a6cb78b1fc 100644
--- a/ethereum.go
+++ b/ethereum.go
@@ -149,7 +149,9 @@ func (s *Ethereum) IsUpToDate() bool {
 	})
 	return upToDate
 }
-
+func (s *Ethereum) PushPeer(peer *Peer) {
+	s.peers.PushBack(peer)
+}
 func (s *Ethereum) IsListening() bool {
 	return s.listening
 }
@@ -159,14 +161,11 @@ func (s *Ethereum) AddPeer(conn net.Conn) {
 
 	if peer != nil {
 		if s.peers.Len() < s.MaxPeers {
-			s.peers.PushBack(peer)
 			peer.Start()
 		} else {
 			ethutil.Config.Log.Debugf("[SERV] Max connected peers reached. Not adding incoming peer.")
 		}
 	}
-
-	s.reactor.Post("peerList", s.peers)
 }
 
 func (s *Ethereum) ProcessPeerList(addrs []string) {
@@ -233,12 +232,7 @@ func (s *Ethereum) ConnectToPeer(addr string) error {
 			return nil
 		}
 
-		peer := NewOutboundPeer(addr, s, s.serverCaps)
-
-		s.peers.PushBack(peer)
-
-		ethutil.Config.Log.Infof("[SERV] Adding peer (%s) %d / %d\n", addr, s.peers.Len(), s.MaxPeers)
-		s.reactor.Post("peerList", s.peers)
+		NewOutboundPeer(addr, s, s.serverCaps)
 	}
 
 	return nil
diff --git a/peer.go b/peer.go
index 5362b0f778..2ece9b3596 100644
--- a/peer.go
+++ b/peer.go
@@ -2,6 +2,7 @@ package eth
 
 import (
 	"bytes"
+	"container/list"
 	"fmt"
 	"github.com/ethereum/eth-go/ethchain"
 	"github.com/ethereum/eth-go/ethutil"
@@ -615,6 +616,30 @@ func (p *Peer) pushPeers() {
 func (p *Peer) handleHandshake(msg *ethwire.Msg) {
 	c := msg.Data
 
+	// Set pubkey
+	p.pubkey = c.Get(5).Bytes()
+
+	if p.pubkey == nil {
+		//ethutil.Config.Log.Debugln("Pubkey required, not supplied in handshake.")
+		p.Stop()
+		return
+	}
+
+	usedPub := 0
+	// This peer is already added to the peerlist so we expect to find a double pubkey at least once
+
+	eachPeer(p.ethereum.Peers(), func(peer *Peer, e *list.Element) {
+		if bytes.Compare(p.pubkey, peer.pubkey) == 0 {
+			usedPub++
+		}
+	})
+
+	if usedPub > 0 {
+		//ethutil.Config.Log.Debugf("Pubkey %x found more then once. Already connected to client.", p.pubkey)
+		p.Stop()
+		return
+	}
+
 	if c.Get(0).Uint() != ProtocolVersion {
 		ethutil.Config.Log.Debugf("Invalid peer version. Require protocol: %d. Received: %d\n", ProtocolVersion, c.Get(0).Uint())
 		p.Stop()
@@ -626,7 +651,6 @@ func (p *Peer) handleHandshake(msg *ethwire.Msg) {
 
 	// If this is an inbound connection send an ack back
 	if p.inbound {
-		p.pubkey = c.Get(5).Bytes()
 		p.port = uint16(c.Get(4).Uint())
 
 		// Self connect detection
@@ -648,6 +672,11 @@ func (p *Peer) handleHandshake(msg *ethwire.Msg) {
 		p.SetVersion(c.Get(2).Str())
 	}
 
+	p.ethereum.PushPeer(p)
+	p.ethereum.reactor.Post("peerList", p.ethereum.Peers())
+
+	ethutil.Config.Log.Infof("[SERV] Added peer (%s) %d / %d\n", p.conn.RemoteAddr(), p.ethereum.Peers().Len(), p.ethereum.MaxPeers)
+
 	// Catch up with the connected peer
 	if !p.ethereum.IsUpToDate() {
 		ethutil.Config.Log.Debugln("Already syncing up with a peer; sleeping")