From 995fab2ebc3b145a1dbb85841c5241cd024362ac Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Mon, 13 Apr 2015 17:34:08 +0200
Subject: [PATCH] p2p: fix yet another disconnect hang

Peer.readLoop will only terminate if the connection is closed. Fix the
hang by closing the connection before waiting for readLoop to terminate.

This also removes the british disconnect procedure where we're waiting
for the remote end to close the connection. I have confirmed with
@subtly that cpp-ethereum doesn't adhere to it either.
---
 p2p/peer.go | 30 ++++++++----------------------
 1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/p2p/peer.go b/p2p/peer.go
index 7bc4f9cf6b..1262ba64a7 100644
--- a/p2p/peer.go
+++ b/p2p/peer.go
@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"sort"
 	"sync"
@@ -20,8 +19,7 @@ const (
 	baseProtocolLength     = uint64(16)
 	baseProtocolMaxMsgSize = 10 * 1024 * 1024
 
-	pingInterval          = 15 * time.Second
-	disconnectGracePeriod = 2 * time.Second
+	pingInterval = 15 * time.Second
 )
 
 const (
@@ -129,39 +127,27 @@ func (p *Peer) run() DiscReason {
 	case err := <-readErr:
 		if r, ok := err.(DiscReason); ok {
 			reason = r
-			break
+		} else {
+			// Note: We rely on protocols to abort if there is a write
+			// error. It might be more robust to handle them here as well.
+			p.DebugDetailf("Read error: %v\n", err)
+			reason = DiscNetworkError
 		}
-		// Note: We rely on protocols to abort if there is a write
-		// error. It might be more robust to handle them here as well.
-		p.DebugDetailf("Read error: %v\n", err)
-		p.conn.Close()
-		reason = DiscNetworkError
 	case err := <-p.protoErr:
 		reason = discReasonForError(err)
 	case reason = <-p.disc:
 	}
 
 	close(p.closed)
+	p.politeDisconnect(reason)
 	p.wg.Wait()
-	if reason != DiscNetworkError {
-		p.politeDisconnect(reason)
-	}
 	p.Debugf("Disconnected: %v\n", reason)
 	return reason
 }
 
 func (p *Peer) politeDisconnect(reason DiscReason) {
-	done := make(chan struct{})
-	go func() {
+	if reason != DiscNetworkError {
 		SendItems(p.rw, discMsg, uint(reason))
-		// Wait for the other side to close the connection.
-		// Discard any data that they send until then.
-		io.Copy(ioutil.Discard, p.conn)
-		close(done)
-	}()
-	select {
-	case <-done:
-	case <-time.After(disconnectGracePeriod):
 	}
 	p.conn.Close()
 }