From 1198c5b1c9296f284ac83a0931f52f2b964c393e Mon Sep 17 00:00:00 2001
From: Alex Kocharin <alex@kocharin.ru>
Date: Thu, 19 Nov 2020 16:49:14 +0300
Subject: [PATCH] Fix performance issues when parsing links

close https://github.com/markdown-it/markdown-it/issues/732
---
 lib/helpers/parse_link_destination.js           |  2 ++
 test/fixtures/markdown-it/commonmark_extras.txt | 12 ++++++++++++
 test/pathological.js                            |  4 ++--
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/helpers/parse_link_destination.js b/lib/helpers/parse_link_destination.js
index 10953b645..6c1423c6a 100644
--- a/lib/helpers/parse_link_destination.js
+++ b/lib/helpers/parse_link_destination.js
@@ -22,6 +22,7 @@ module.exports = function parseLinkDestination(str, pos, max) {
     while (pos < max) {
       code = str.charCodeAt(pos);
       if (code === 0x0A /* \n */) { return result; }
+      if (code === 0x3C /* < */) { return result; }
       if (code === 0x3E /* > */) {
         result.pos = pos + 1;
         result.str = unescapeAll(str.slice(start + 1, pos));
@@ -58,6 +59,7 @@ module.exports = function parseLinkDestination(str, pos, max) {
 
     if (code === 0x28 /* ( */) {
       level++;
+      if (level > 32) { return result; }
     }
 
     if (code === 0x29 /* ) */) {
diff --git a/test/fixtures/markdown-it/commonmark_extras.txt b/test/fixtures/markdown-it/commonmark_extras.txt
index 4cda25712..d82d8d50f 100644
--- a/test/fixtures/markdown-it/commonmark_extras.txt
+++ b/test/fixtures/markdown-it/commonmark_extras.txt
@@ -255,6 +255,18 @@ List item terminating quote should not be paragraph continuation
 </ol>
 .
 
+
+Link destination cannot contain '<'
+.
+[](<foo<bar>)
+
+[](<foo\<bar>)
+.
+<p>[](&lt;foo<bar>)</p>
+<p><a href="foo%3Cbar"></a></p>
+.
+
+
 Coverage. Directive can terminate paragraph.
 .
 a
diff --git a/test/pathological.js b/test/pathological.js
index 5ae258819..7e9991a9f 100644
--- a/test/pathological.js
+++ b/test/pathological.js
@@ -121,14 +121,14 @@ describe('Pathological', function () {
     );
   });
 
-  it.skip('unclosed links A', function () {
+  it('unclosed links A', function () {
     assert.match(
       md.render('[a](<b'.repeat(30000)),
       /(\[a\]\(&lt;b){30000}/
     );
   });
 
-  it.skip('unclosed links B', function () {
+  it('unclosed links B', function () {
     assert.match(
       md.render('[a](b'.repeat(30000)),
       /(\[a\]\(b){30000}/