From 284211c18fa1ffb28aadb46ed7d92d225699149a Mon Sep 17 00:00:00 2001
From: Xiliang Chen <xlchen1291@gmail.com>
Date: Thu, 6 Dec 2018 23:21:17 +1300
Subject: [PATCH] Fix incorrectly report bad peer issue

A block request can result an empty response if the requested hight is too high, which shouldn't resulting the peer get banned just becuase it is behind
---
 core/network/src/sync.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/core/network/src/sync.rs b/core/network/src/sync.rs
index 1287beffe95bd..8fbf052420ad5 100644
--- a/core/network/src/sync.rs
+++ b/core/network/src/sync.rs
@@ -239,6 +239,13 @@ impl<B: BlockT> ChainSync<B> {
 							}
 						},
 						None => {
+							if n > As::sa(0) {
+								trace!(target:"sync", "Ancestry block not found for peer {}: block #{}", who, n);
+								let n = n - As::sa(1);
+								peer.state = PeerSyncState::AncestorSearch(n);
+								Self::request_ancestry(protocol, who, n);
+								return None;
+							}
 							trace!(target:"sync", "Invalid response when searching for ancestor from {}", who);
 							protocol.report_peer(who, Severity::Bad("Invalid response when searching for ancestor"));
 							return None;