From e91d7bacbd542721ab567e8817cad0630a8a927b Mon Sep 17 00:00:00 2001
From: Andrew Ayer <agwa@andrewayer.name>
Date: Thu, 18 Feb 2016 10:23:07 -0800
Subject: [PATCH] Minor cleanup to improve encapsulation

---
 auditing.go   | 11 ++---------
 cmd/common.go | 10 ++++------
 scanner.go    | 10 +++++-----
 3 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/auditing.go b/auditing.go
index 065564c..2d94f27 100644
--- a/auditing.go
+++ b/auditing.go
@@ -13,7 +13,7 @@ func reverseHashes (hashes []ct.MerkleTreeNode) {
 	}
 }
 
-func VerifyConsistencyProof (proof ct.ConsistencyProof, first *ct.SignedTreeHead, second *ct.SignedTreeHead) (bool, []ct.MerkleTreeNode) {
+func VerifyConsistencyProof (proof ct.ConsistencyProof, first *ct.SignedTreeHead, second *ct.SignedTreeHead) (bool, *MerkleTreeBuilder) {
 	if second.TreeSize < first.TreeSize {
 		// Can't be consistent if tree got smaller
 		return false, nil
@@ -97,7 +97,7 @@ func VerifyConsistencyProof (proof ct.ConsistencyProof, first *ct.SignedTreeHead
 
 	reverseHashes(leftHashes)
 
-	return true, leftHashes
+	return true, &MerkleTreeBuilder{stack: leftHashes, size: first.TreeSize}
 }
 
 func hashLeaf (leafBytes []byte) ct.MerkleTreeNode {
@@ -120,13 +120,6 @@ type MerkleTreeBuilder struct {
 	size		uint64 // number of hashes added so far
 }
 
-func ResumedMerkleTreeBuilder (hashes []ct.MerkleTreeNode, size uint64) *MerkleTreeBuilder {
-	return &MerkleTreeBuilder{
-		stack: hashes,
-		size: size,
-	}
-}
-
 func (builder *MerkleTreeBuilder) Add (hash ct.MerkleTreeNode) {
 	builder.stack = append(builder.stack, hash)
 	builder.size++
diff --git a/cmd/common.go b/cmd/common.go
index 7fd568c..e3342eb 100644
--- a/cmd/common.go
+++ b/cmd/common.go
@@ -13,7 +13,6 @@ import (
 	"path/filepath"
 
 	"src.agwa.name/ctwatch"
-	"github.com/google/certificate-transparency/go/client"
 )
 
 var batchSize = flag.Int("batch_size", 1000, "Max number of entries to request at per call to get-entries")
@@ -133,14 +132,13 @@ func Main (argStateDir string, processCallback ctwatch.ProcessCallback) {
 			os.Exit(3)
 		}
 
-		logClient := client.New(logUri)
 		opts := ctwatch.ScannerOptions{
 			BatchSize:     *batchSize,
 			NumWorkers:    *numWorkers,
 			ParallelFetch: *parallelFetch,
 			Quiet:         !*verbose,
 		}
-		scanner := ctwatch.NewScanner(logUri, logKey, logClient, opts)
+		scanner := ctwatch.NewScanner(logUri, logKey, opts)
 
 		latestSTH, err := scanner.GetSTH()
 		if err != nil {
@@ -161,7 +159,9 @@ func Main (argStateDir string, processCallback ctwatch.ProcessCallback) {
 		if latestSTH.TreeSize > startIndex {
 			var treeBuilder *ctwatch.MerkleTreeBuilder
 			if prevSTH != nil {
-				valid, nodes, err := scanner.CheckConsistency(prevSTH, latestSTH)
+				var valid bool
+				var err error
+				valid, treeBuilder, err = scanner.CheckConsistency(prevSTH, latestSTH)
 				if err != nil {
 					fmt.Fprintf(os.Stderr, "%s: Error fetching consistency proof: %s: %s\n", os.Args[0], logUri, err)
 					exitCode = 1
@@ -172,8 +172,6 @@ func Main (argStateDir string, processCallback ctwatch.ProcessCallback) {
 					exitCode = 1
 					continue
 				}
-
-				treeBuilder = ctwatch.ResumedMerkleTreeBuilder(nodes, prevSTH.TreeSize)
 			} else {
 				treeBuilder = &ctwatch.MerkleTreeBuilder{}
 			}
diff --git a/scanner.go b/scanner.go
index 7345008..e11318c 100644
--- a/scanner.go
+++ b/scanner.go
@@ -185,7 +185,7 @@ func (s *Scanner) GetSTH() (*ct.SignedTreeHead, error) {
 	return latestSth, nil
 }
 
-func (s *Scanner) CheckConsistency(first *ct.SignedTreeHead, second *ct.SignedTreeHead) (bool, []ct.MerkleTreeNode, error) {
+func (s *Scanner) CheckConsistency(first *ct.SignedTreeHead, second *ct.SignedTreeHead) (bool, *MerkleTreeBuilder, error) {
 	var proof ct.ConsistencyProof
 
 	if first.TreeSize > second.TreeSize {
@@ -203,8 +203,8 @@ func (s *Scanner) CheckConsistency(first *ct.SignedTreeHead, second *ct.SignedTr
 		}
 	}
 
-	valid, builderNodes := VerifyConsistencyProof(proof, first, second)
-	return valid, builderNodes, nil
+	valid, treeBuilder := VerifyConsistencyProof(proof, first, second)
+	return valid, treeBuilder, nil
 }
 
 func (s *Scanner) Scan(startIndex int64, endIndex int64, processCert ProcessCallback, treeBuilder *MerkleTreeBuilder) error {
@@ -268,11 +268,11 @@ func (s *Scanner) Scan(startIndex int64, endIndex int64, processCert ProcessCall
 
 // Creates a new Scanner instance using |client| to talk to the log, and taking
 // configuration options from |opts|.
-func NewScanner(logUri string, publicKey crypto.PublicKey, client *client.LogClient, opts ScannerOptions) *Scanner {
+func NewScanner(logUri string, publicKey crypto.PublicKey, opts ScannerOptions) *Scanner {
 	var scanner Scanner
 	scanner.LogUri = logUri
 	scanner.publicKey = publicKey
-	scanner.logClient = client
+	scanner.logClient = client.New(logUri)
 	scanner.opts = opts
 	return &scanner
 }