From 0beed6efa4be562474bd382b72af891ab581d401 Mon Sep 17 00:00:00 2001
From: Yemel Jardi <angel.jardi@gmail.com>
Date: Tue, 6 Jan 2015 12:08:42 -0300
Subject: [PATCH] Refactor HDPublicKey path validation

---
 lib/hdpublickey.js  | 40 +++++++++++++++++-----------------------
 test/hdpublickey.js | 34 +++++++++++++++++++++++++++-------
 2 files changed, 44 insertions(+), 30 deletions(-)

diff --git a/lib/hdpublickey.js b/lib/hdpublickey.js
index 979faf965..64da85a9b 100644
--- a/lib/hdpublickey.js
+++ b/lib/hdpublickey.js
@@ -65,20 +65,23 @@ function HDPublicKey(arg) {
   }
 }
 
-
 /**
  * Verifies that a given path is valid.
  *
  * @param {string|number} arg
  * @return {boolean}
  */
-HDPublicKey.prototype.isValidPath = function(arg) {
-  try {
-    this.derive(arg);
-    return true;
-  } catch (err) {
-    return false;
+HDPublicKey.isValidPath = function(arg) {
+  if (_.isString(arg)) {
+    var indexes = HDPrivateKey._getDerivationIndexes(arg);
+    return indexes !== null && _.all(indexes, HDPublicKey.isValidPath);
   }
+
+  if (_.isNumber(arg)) {
+    return arg >= 0 && arg < HDPublicKey.Hardened;
+  }
+
+  return false;
 };
 
 /**
@@ -149,25 +152,16 @@ HDPublicKey.prototype._deriveFromString = function (path) {
   /* jshint maxcomplexity: 8 */
   if (_.contains(path, "'")) {
     throw new hdErrors.InvalidIndexCantDeriveHardened();
-  }
-
-  var steps = path.split('/');
-
-  // Special cases:
-  if (_.contains(HDPublicKey.RootElementAlias, path)) {
-    return this;
-  }
-  if (!_.contains(HDPublicKey.RootElementAlias, steps[0])) {
+  } else if (!HDPublicKey.isValidPath(path)) {
     throw new hdErrors.InvalidPath(path);
   }
-  steps = steps.slice(1);
 
-  var result = this;
-  for (var step in steps) {
-    var index = parseInt(steps[step]);
-    result = result._deriveWithNumber(index);
-  }
-  return result;
+  var indexes = HDPrivateKey._getDerivationIndexes(path);
+  var derived = indexes.reduce(function(prev, index) {
+    return prev._deriveWithNumber(index);
+  }, this);
+
+  return derived;
 };
 
 /**
diff --git a/test/hdpublickey.js b/test/hdpublickey.js
index dd73aca7a..f67b1e426 100644
--- a/test/hdpublickey.js
+++ b/test/hdpublickey.js
@@ -221,20 +221,40 @@ describe('HDPublicKey interface', function() {
     });
 
   it('validates correct paths', function() {
-    var publicKey = new HDPublicKey(xpubkey);
-    var valid = publicKey.isValidPath('m/123/12');
+    var valid;
+
+    valid = HDPublicKey.isValidPath('m/123/12');
     valid.should.equal(true);
 
-    var valid = publicKey.isValidPath(123, true);
+    valid = HDPublicKey.isValidPath('m');
+    valid.should.equal(true);
+
+    valid = HDPublicKey.isValidPath(123);
     valid.should.equal(true);
   });
 
-  it('validates illegal paths', function() {
-    var publicKey = new HDPublicKey(xpubkey);
-    var valid = publicKey.isValidPath('m/-1/12');
+  it('rejects illegal paths', function() {
+    var valid;
+    
+    valid = HDPublicKey.isValidPath('m/-1/12');
     valid.should.equal(false);
 
-    var valid = publicKey.isValidPath(HDPublicKey.Hardened);
+    valid = HDPublicKey.isValidPath("m/0'/12");
+    valid.should.equal(false);
+
+    valid = HDPublicKey.isValidPath("m/8000000000/12");
+    valid.should.equal(false);
+
+    valid = HDPublicKey.isValidPath('bad path');
+    valid.should.equal(false);
+
+    valid = HDPublicKey.isValidPath(-1);
+    valid.should.equal(false);
+
+    valid = HDPublicKey.isValidPath(8000000000);
+    valid.should.equal(false);
+
+    valid = HDPublicKey.isValidPath(HDPublicKey.Hardened);
     valid.should.equal(false);
   });