Replace linkRegex with xurls library (#6261)

* Replace linkRegex with xurls library

Rather than maintaining a complicated regex to match URLs for
autolinking, gitea can use this existing go library that takes care of
the matching with very little code change to gitea itself. After
spending a while trying to find the perfect regex for all cases this library
still works better as it is more flexible than a single regex ever will be.

This will also fix the following issues: #5844 #3095 #3381

This passes all our current tests and I've added new ones mentioned in
those issues as well.

* Use xurls.StrictMatchingScheme instead of xurls.Strict

This is much faster and we only care about https? links to preserve
existing behavior.

Gopkg.toml

@@ -113,3 +113,7 @@ ignored = ["google.golang.org/appengine*"]
 [[constraint]]
   name = "github.com/prometheus/client_golang"
   version = "0.9.0"
+
+[[constraint]]
+  name = "github.com/mvdan/xurls"
+  version = "2.0.0"

modules/markup/html.go

@@ -17,6 +17,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 
 	"github.com/Unknwon/com"
+	"github.com/mvdan/xurls"
 	"golang.org/x/net/html"
 	"golang.org/x/net/html/atom"
 )
@@ -64,9 +65,7 @@ var (
 	//   https://html.spec.whatwg.org/multipage/input.html#e-mail-state-(type%3Demail)
 	emailRegex = regexp.MustCompile("[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])?)*")
 
-	// matches http/https links. used for autlinking those. partly modified from
-	// the original present in autolink.js
-	linkRegex = regexp.MustCompile(`(?:(?:http|https):\/\/(?:[\-;:&=\+\$,\w]+@)?[A-Za-z0-9\.\-]+(?:\.|[\-;:&=\+\$,\w]+@)[A-Za-z0-9\.\-]+)(?:(?:\/[\+~%\/\.\w\-]*)?\??(?:[\-\+:=&;%@\.\w]*)#?(?:[\.\!\/\\\w]*))?`)
+	linkRegex, _ = xurls.StrictMatchingScheme("https?://")
 )
 
 // regexp for full links to issues/pulls

modules/markup/html_test.go

@@ -104,6 +104,15 @@ func TestRender_links(t *testing.T) {
 	test(
 		"http://142.42.1.1/",
 		`<p><a href="http://142.42.1.1/" rel="nofollow">http://142.42.1.1/</a></p>`)
+	test(
+		"https://github.com/go-gitea/gitea/?p=aaa/bbb.html#ccc-ddd",
+		`<p><a href="https://github.com/go-gitea/gitea/?p=aaa/bbb.html#ccc-ddd" rel="nofollow">https://github.com/go-gitea/gitea/?p=aaa/bbb.html#ccc-ddd</a></p>`)
+	test(
+		"https://en.wikipedia.org/wiki/URL_(disambiguation)",
+		`<p><a href="https://en.wikipedia.org/wiki/URL_(disambiguation)" rel="nofollow">https://en.wikipedia.org/wiki/URL_(disambiguation)</a></p>`)
+	test(
+		"https://foo_bar.example.com/",
+		`<p><a href="https://foo_bar.example.com/" rel="nofollow">https://foo_bar.example.com/</a></p>`)
 
 	// Test that should *not* be turned into URL
 	test(