Fix quadratic complexity in autolinks

close https://github.com/markdown-it/markdown-it/issues/737

CHANGELOG.md

@@ -11,9 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `[](<foo<bar>)` is no longer a valid link.
 - `[](url (xxx())` is no longer a valid link.
 - `[](url\ xxx)` is no longer a valid link.
-- Fix performance issues when parsing links, #732, #734.
+- Fix performance issues when parsing links (#732, #734), backticks, (#733, #736),
-- Fix performance issues when parsing backticks, #733, #736.
+  emphases (#735), and autolinks (#737).
-- Fix performance issues when parsing emphases, #735.
 
 
 ## [12.0.2] - 2020-10-23

lib/rules_inline/autolink.js

@@ -4,24 +4,31 @@
 
 
 /*eslint max-len:0*/
-var EMAIL_RE    = /^<([a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*)>/;
+var EMAIL_RE    = /^([a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*)$/;
-var AUTOLINK_RE = /^<([a-zA-Z][a-zA-Z0-9+.\-]{1,31}):([^<>\x00-\x20]*)>/;
+var AUTOLINK_RE = /^([a-zA-Z][a-zA-Z0-9+.\-]{1,31}):([^<>\x00-\x20]*)$/;
 
 
 module.exports = function autolink(state, silent) {
-  var tail, linkMatch, emailMatch, url, fullUrl, token,
+  var url, fullUrl, token, ch, start, max,
       pos = state.pos;
 
   if (state.src.charCodeAt(pos) !== 0x3C/* < */) { return false; }
 
-  tail = state.src.slice(pos);
+  start = state.pos;
+  max = state.posMax;
 
-  if (tail.indexOf('>') < 0) { return false; }
+  for (;;) {
+    if (++pos >= max) return false;
 
-  if (AUTOLINK_RE.test(tail)) {
+    ch = state.src.charCodeAt(pos);
-    linkMatch = tail.match(AUTOLINK_RE);
 
-    url = linkMatch[0].slice(1, -1);
+    if (ch === 0x3C /* < */) return false;
+    if (ch === 0x3E /* > */) break;
+  }
+
+  url = state.src.slice(start + 1, pos);
+
+  if (AUTOLINK_RE.test(url)) {
     fullUrl = state.md.normalizeLink(url);
     if (!state.md.validateLink(fullUrl)) { return false; }
 
@@ -39,14 +46,11 @@ module.exports = function autolink(state, silent) {
       token.info    = 'auto';
     }
 
-    state.pos += linkMatch[0].length;
+    state.pos += url.length + 2;
     return true;
   }
 
-  if (EMAIL_RE.test(tail)) {
+  if (EMAIL_RE.test(url)) {
-    emailMatch = tail.match(EMAIL_RE);
-
-    url = emailMatch[0].slice(1, -1);
     fullUrl = state.md.normalizeLink('mailto:' + url);
     if (!state.md.validateLink(fullUrl)) { return false; }
 
@@ -64,7 +68,7 @@ module.exports = function autolink(state, silent) {
       token.info    = 'auto';
     }
 
-    state.pos += emailMatch[0].length;
+    state.pos += url.length + 2;
     return true;
   }
 

test/pathological.js

@@ -126,5 +126,9 @@ describe('Pathological sequences speed', () => {
     it('backtick ``\\``\\`` pattern', async () => {
       await test_pattern('``\\'.repeat(50000));
     });
+
+    it('autolinks <<<<...<<> pattern', async () => {
+      await test_pattern('<'.repeat(400000) + '>');
+    });
   });
 });