From b9359981f447f1f9b14ce82da60c5cf5c78df876 Mon Sep 17 00:00:00 2001
From: Jeffrey Wilcke <geffobscura@gmail.com>
Date: Fri, 25 Sep 2015 13:56:53 +0200
Subject: [PATCH] xeth: fixed nil pointer of filter retrieval

This fix addresses an issue with filters that were (possibly) not yet
added to the filter queues but were expected. I've added additional nil
checks making sure it doesn't crash and swapped the installation of the
filter around so it's installed before use.

Closes #1665
---
 xeth/xeth.go | 46 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/xeth/xeth.go b/xeth/xeth.go
index 00b70da6c..623b3a963 100644
--- a/xeth/xeth.go
+++ b/xeth/xeth.go
@@ -532,8 +532,10 @@ func (self *XEth) NewLogFilter(earliest, latest int64, skip, max int, address []
 	self.logMu.Lock()
 	defer self.logMu.Unlock()
 
-	var id int
 	filter := core.NewFilter(self.backend)
+	id := self.filterManager.InstallFilter(filter)
+	self.logQueue[id] = &logQueue{timeout: time.Now()}
+
 	filter.SetEarliestBlock(earliest)
 	filter.SetLatestBlock(latest)
 	filter.SetSkip(skip)
@@ -544,10 +546,10 @@ func (self *XEth) NewLogFilter(earliest, latest int64, skip, max int, address []
 		self.logMu.Lock()
 		defer self.logMu.Unlock()
 
-		self.logQueue[id].add(logs...)
+		if queue := self.logQueue[id]; queue != nil {
+			queue.add(logs...)
+		}
 	}
-	id = self.filterManager.InstallFilter(filter)
-	self.logQueue[id] = &logQueue{timeout: time.Now()}
 
 	return id
 }
@@ -556,16 +558,18 @@ func (self *XEth) NewTransactionFilter() int {
 	self.transactionMu.Lock()
 	defer self.transactionMu.Unlock()
 
-	var id int
 	filter := core.NewFilter(self.backend)
+	id := self.filterManager.InstallFilter(filter)
+	self.transactionQueue[id] = &hashQueue{timeout: time.Now()}
+
 	filter.TransactionCallback = func(tx *types.Transaction) {
 		self.transactionMu.Lock()
 		defer self.transactionMu.Unlock()
 
-		self.transactionQueue[id].add(tx.Hash())
+		if queue := self.transactionQueue[id]; queue != nil {
+			queue.add(tx.Hash())
+		}
 	}
-	id = self.filterManager.InstallFilter(filter)
-	self.transactionQueue[id] = &hashQueue{timeout: time.Now()}
 	return id
 }
 
@@ -573,16 +577,18 @@ func (self *XEth) NewBlockFilter() int {
 	self.blockMu.Lock()
 	defer self.blockMu.Unlock()
 
-	var id int
 	filter := core.NewFilter(self.backend)
+	id := self.filterManager.InstallFilter(filter)
+	self.blockQueue[id] = &hashQueue{timeout: time.Now()}
+
 	filter.BlockCallback = func(block *types.Block, logs state.Logs) {
 		self.blockMu.Lock()
 		defer self.blockMu.Unlock()
 
-		self.blockQueue[id].add(block.Hash())
+		if queue := self.blockQueue[id]; queue != nil {
+			queue.add(block.Hash())
+		}
 	}
-	id = self.filterManager.InstallFilter(filter)
-	self.blockQueue[id] = &hashQueue{timeout: time.Now()}
 	return id
 }
 
@@ -1022,16 +1028,24 @@ func (m callmsg) Value() *big.Int               { return m.value }
 func (m callmsg) Data() []byte                  { return m.data }
 
 type logQueue struct {
+	mu sync.Mutex
+
 	logs    state.Logs
 	timeout time.Time
 	id      int
 }
 
 func (l *logQueue) add(logs ...*state.Log) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
 	l.logs = append(l.logs, logs...)
 }
 
 func (l *logQueue) get() state.Logs {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
 	l.timeout = time.Now()
 	tmp := l.logs
 	l.logs = nil
@@ -1039,16 +1053,24 @@ func (l *logQueue) get() state.Logs {
 }
 
 type hashQueue struct {
+	mu sync.Mutex
+
 	hashes  []common.Hash
 	timeout time.Time
 	id      int
 }
 
 func (l *hashQueue) add(hashes ...common.Hash) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
 	l.hashes = append(l.hashes, hashes...)
 }
 
 func (l *hashQueue) get() []common.Hash {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
 	l.timeout = time.Now()
 	tmp := l.hashes
 	l.hashes = nil