From 357160257c19524060ec79425c065f5039220138 Mon Sep 17 00:00:00 2001
From: Dave Collins <davec@conformal.com>
Date: Tue, 30 Jul 2013 15:29:15 -0500
Subject: [PATCH] Allow checkpoints to work with all networks.

Previously the main network checkpoints were being used for unrecognized
networks.  This commit changes the code so that no checkpoints are used in
that scenario.
---
 checkpoints.go | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/checkpoints.go b/checkpoints.go
index 818b2fb9..64e67e63 100644
--- a/checkpoints.go
+++ b/checkpoints.go
@@ -60,8 +60,9 @@ var checkpointDataMainNet = checkpointData{
 	checkpointsByHeight: nil, // Automatically generated in init.
 }
 
-// checkpointDataTestNet contains checkpoint data for the test network.
-var checkpointDataTestNet = checkpointData{
+// checkpointDataTestNet3 contains checkpoint data for the test network (version
+// 3).
+var checkpointDataTestNet3 = checkpointData{
 	checkpoints: []Checkpoint{
 		{546, newShaHashFromStr("000000002a936ca763904c3c35fce2f3556c559c0214345d31b1bcebf76acb70")},
 	},
@@ -89,18 +90,18 @@ func (b *BlockChain) DisableCheckpoints(disable bool) {
 func (b *BlockChain) checkpointData() *checkpointData {
 	switch b.btcnet {
 	case btcwire.TestNet3:
-		return &checkpointDataTestNet
+		return &checkpointDataTestNet3
 	case btcwire.MainNet:
-		fallthrough
-	default:
 		return &checkpointDataMainNet
 	}
+	return nil
 }
 
 // LatestCheckpoint returns the most recent checkpoint (regardless of whether it
-// is already known).  When checkpoints are disabled it will return nil.
+// is already known).  When checkpoints are disabled or there are no checkpoints
+// for the active network, it will return nil.
 func (b *BlockChain) LatestCheckpoint() *Checkpoint {
-	if b.noCheckpoints {
+	if b.noCheckpoints || b.checkpointData() == nil {
 		return nil
 	}
 
@@ -112,7 +113,7 @@ func (b *BlockChain) LatestCheckpoint() *Checkpoint {
 // match the hard-coded checkpoint data.  It also returns true if there is no
 // checkpoint data for the passed block height.
 func (b *BlockChain) verifyCheckpoint(height int64, hash *btcwire.ShaHash) bool {
-	if b.noCheckpoints {
+	if b.noCheckpoints || b.checkpointData() == nil {
 		return true
 	}
 
@@ -130,7 +131,7 @@ func (b *BlockChain) verifyCheckpoint(height int64, hash *btcwire.ShaHash) bool
 // associated block.  It returns nil if a checkpoint can't be found (this should
 // really only happen for blocks before the first checkpoint).
 func (b *BlockChain) findLatestKnownCheckpoint() (*btcutil.Block, error) {
-	if b.noCheckpoints {
+	if b.noCheckpoints || b.checkpointData() == nil {
 		return nil, nil
 	}
 
@@ -248,7 +249,7 @@ func init() {
 	// when the package loads.
 	checkpointInitializeList := []*checkpointData{
 		&checkpointDataMainNet,
-		&checkpointDataTestNet,
+		&checkpointDataTestNet3,
 	}
 	for _, data := range checkpointInitializeList {
 		data.checkpointsByHeight = make(map[int64]*Checkpoint)