Issue 4878 - Start using ESLint for adblockpluscore

lib/rsa.js

Index: lib/rsa.js
diff --git a/lib/rsa.js b/lib/rsa.js
index 6c6638cb266a491b0813a3169534c61f4aba9d48..2d853a3dc2d7297308b7ce095f86b35712b71beb 100644
--- a/lib/rsa.js
+++ b/lib/rsa.js
@@ -15,6 +15,8 @@
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+"use strict";
+
 /**
  * This is a specialized RSA library meant only to verify SHA1-based signatures.
  */
@@ -25,9 +27,9 @@ let Rusha = require("rusha");
 let rusha = new Rusha();
 
 // Define ASN.1 templates for the data structures used
-function seq()
+function seq(...args)
 {
-  return {type: 0x30, children: Array.prototype.slice.call(arguments)};
+  return {type: 0x30, children: args};
 }
 function obj(id)
 {
@@ -48,22 +50,30 @@ function octetResult(id)
 
 // See http://www.cryptopp.com/wiki/Keys_and_Formats#RSA_PublicKey
 // 2A 86 48 86 F7 0D 01 01 01 means 1.2.840.113549.1.1.1
-var publicKeyTemplate = seq(seq(obj("\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01"), {}), bitStr(seq(intResult("n"), intResult("e"))));
+let publicKeyTemplate = seq(
+  seq(obj("\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01"), {}),
+  bitStr(seq(intResult("n"), intResult("e")))
+);
 
 // See http://tools.ietf.org/html/rfc3447#section-9.2 step 2
 // 2B 0E 03 02 1A means 1.3.14.3.2.26
-var signatureTemplate = seq(seq(obj("\x2B\x0E\x03\x02\x1A"), {}), octetResult("sha1"));
+let signatureTemplate = seq(
+  seq(obj("\x2B\x0E\x03\x02\x1A"), {}),
+  octetResult("sha1")
+);
 
 /**
  * Reads ASN.1 data matching the template passed in. This will throw an
  * exception if the data format doesn't match the template. On success an
  * object containing result properties is returned.
- *
- * See http://luca.ntop.org/Teaching/Appunti/asn1.html for info on the format.
+ * @see http://luca.ntop.org/Teaching/Appunti/asn1.html for info on the format.
+ * @param {string} data
+ * @param {Object} templ
+ * @returns {Object}
  */
 function readASN1(data, templ)
 {
-  var pos = 0;
+  let pos = 0;
   function next()
   {
     return data.charCodeAt(pos++);
@@ -71,26 +81,25 @@ function readASN1(data, templ)
 
   function readLength()
   {
-    var len = next();
+    let len = next();
     if (len & 0x80)
     {
-      var cnt = len & 0x7F;
+      let cnt = len & 0x7F;
       if (cnt > 2 || cnt == 0)
         throw "Unsupported length";
 
       len = 0;
-      for (var i = 0; i < cnt; i++)
+      for (let i = 0; i < cnt; i++)
         len += next() << (cnt - 1 - i) * 8;
       return len;
     }
-    else
-      return len;
+    return len;
   }
 
   function readNode(curTempl)
   {
-    var type = next();
-    var len = readLength();
+    let type = next();
+    let len = readLength();
     if ("type" in curTempl && curTempl.type != type)
       throw "Unexpected type";
     if ("content" in curTempl && curTempl.content != data.substr(pos, len))
@@ -99,7 +108,8 @@ function readASN1(data, templ)
       out[curTempl.out] = new BigInteger(data.substr(pos, len), 256);
     if ("children" in curTempl)
     {
-      var i, end;
+      let i;
+      let end;

[Sebastian Noack, 2017/02/21 09:19:31]

These variables aren't used outside of the loop, so the declaration should go
inside the loop head.

[kzar, 2017/02/21 10:37:02]

They are used outside of the loop.

       for (i = 0, end = pos + len; pos < end; i++)
       {
         if (i >= curTempl.children.length)
@@ -121,7 +131,7 @@ function readASN1(data, templ)
       pos += len;
   }
 
-  var out = {};
+  let out = {};
   readNode(templ);
   if (pos != data.length)
     throw "Too much data";
@@ -131,6 +141,8 @@ function readASN1(data, templ)
 /**
  * Reads a BER-encoded RSA public key. On success returns an object with the
  * properties n and e (the components of the key), otherwise null.
+ * @param {string} key
+ * @return {Object|null}
  */
 function readPublicKey(key)
 {
@@ -140,17 +152,21 @@ function readPublicKey(key)
   }
   catch (e)
   {
-    console.log("Invalid RSA public key: " + e);
+    console.warn("Invalid RSA public key: " + e);
     return null;
   }
 }
 
 /**
  * Checks whether the signature is valid for the given public key and data.
+ * @param {string} key
+ * @param {string} signature
+ * @param {string} data
+ * @return {boolean}
  */
 function verifySignature(key, signature, data)
 {
-  var keyData = readPublicKey(key);
+  let keyData = readPublicKey(key);
   if (!keyData)
     return false;
 
@@ -158,33 +174,33 @@ function verifySignature(key, signature, data)
   keyData.e = parseInt(keyData.e.toString(16), 16);
 
   // Decrypt signature data using RSA algorithm
-  var sigInt = new BigInteger(atob(signature), 256);
-  var digest = sigInt.modPowInt(keyData.e, keyData.n).toString(256);
+  let sigInt = new BigInteger(atob(signature), 256);
+  let digest = sigInt.modPowInt(keyData.e, keyData.n).toString(256);
 
   try
   {
-    var pos = 0;
-    function next()
-    {
-      return digest.charCodeAt(pos++);
-    }
+    let pos = 0;
+    let next = () => digest.charCodeAt(pos++);
 
     // Skip padding, see http://tools.ietf.org/html/rfc3447#section-9.2 step 5
     if (next() != 1)
       throw "Wrong padding in signature digest";
-    while (next() == 255) {}
+    while (next() == 255)
+    {
+      // Empty

[Sebastian Noack, 2017/02/21 09:19:31]

I start to wonder what's the point of the no-empty rule. So far we only
encountered instances of legit empty blocks. Unfortunately, there isn't an
option to allow while-loops with empty block, neither does the "// Empty"
comment add any useful information. Considering that we didn't see a single
inappropriate use of empty blocks yet, and that those would be unlikely to make
it past our code review, we might want to remove that rule altogether.

[kzar, 2017/02/21 10:37:01]

Done. https://codereview.adblockplus.org/29376719/

+    }
     if (digest.charCodeAt(pos - 1) != 0)
       throw "Wrong padding in signature digest";
 
     // Rest is an ASN.1 structure, get the SHA1 hash from it and compare to
     // the real one
-    var sha1 = readASN1(digest.substr(pos), signatureTemplate).sha1;
-    var expected = new BigInteger(rusha.digest(data), 16);
+    let {sha1} = readASN1(digest.substr(pos), signatureTemplate);
+    let expected = new BigInteger(rusha.digest(data), 16);
     return (sha1.compareTo(expected) == 0);
   }
   catch (e)
   {
-    console.log("Invalid encrypted signature: " + e);
+    console.warn("Invalid encrypted signature: " + e);
     return false;
   }
 }