From 41eb1fe8a788a751dbe61efc3a5ce4a2f244770c Mon Sep 17 00:00:00 2001
From: Tom Forbes <tom@tomforb.es>
Date: Sun, 22 Sep 2019 15:03:03 +0100
Subject: [PATCH] Backport noopener links (from commit
 670777b536d38a1aef1d517f6330a77d52ceb02e)

---
 html.go        |  7 +++++++
 inline_test.go | 19 +++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/html.go b/html.go
index e0a6c69..fa044ca 100644
--- a/html.go
+++ b/html.go
@@ -32,6 +32,7 @@ const (
 	HTML_SAFELINK                              // only link to trusted protocols
 	HTML_NOFOLLOW_LINKS                        // only link with rel="nofollow"
 	HTML_NOREFERRER_LINKS                      // only link with rel="noreferrer"
+	HTML_NOOPENER_LINKS                        // only link with rel="noopener"
 	HTML_HREF_TARGET_BLANK                     // add a blank target
 	HTML_TOC                                   // generate a table of contents
 	HTML_OMIT_CONTENTS                         // skip the main contents (for a standalone table of contents)
@@ -445,6 +446,9 @@ func (options *Html) AutoLink(out *bytes.Buffer, link []byte, kind int) {
 	if options.flags&HTML_NOREFERRER_LINKS != 0 && !isRelativeLink(link) {
 		relAttrs = append(relAttrs, "noreferrer")
 	}
+	if options.flags&HTML_NOOPENER_LINKS != 0 && !isRelativeLink(link) {
+		relAttrs = append(relAttrs, "noopener")
+	}
 	if len(relAttrs) > 0 {
 		out.WriteString(fmt.Sprintf("\" rel=\"%s", strings.Join(relAttrs, " ")))
 	}
@@ -559,6 +563,9 @@ func (options *Html) Link(out *bytes.Buffer, link []byte, title []byte, content
 	if options.flags&HTML_NOREFERRER_LINKS != 0 && !isRelativeLink(link) {
 		relAttrs = append(relAttrs, "noreferrer")
 	}
+	if options.flags&HTML_NOOPENER_LINKS != 0 && !isRelativeLink(link) {
+		relAttrs = append(relAttrs, "noopener")
+	}
 	if len(relAttrs) > 0 {
 		out.WriteString(fmt.Sprintf("\" rel=\"%s", strings.Join(relAttrs, " ")))
 	}
diff --git a/inline_test.go b/inline_test.go
index 942c5d3..cb1dfd5 100644
--- a/inline_test.go
+++ b/inline_test.go
@@ -624,6 +624,25 @@ func TestRelAttrLink(t *testing.T) {
 	}
 	doTestsInlineParam(t, nofollownoreferrerTests, Options{}, HTML_SAFELINK|HTML_NOFOLLOW_LINKS|HTML_NOREFERRER_LINKS,
 		HtmlRendererParameters{})
+
+	var noopenerTests = []string{
+		"[foo](http://bar.com/foo/)\n",
+		"<p><a href=\"http://bar.com/foo/\" rel=\"noopener\">foo</a></p>\n",
+
+		"[foo](/bar/)\n",
+		"<p><a href=\"/bar/\">foo</a></p>\n",
+	}
+	doTestsInlineParam(t, noopenerTests, Options{}, HTML_SAFELINK|HTML_NOOPENER_LINKS, HtmlRendererParameters{})
+
+	var nofollownoreferrernoopenerTests = []string{
+		"[foo](http://bar.com/foo/)\n",
+		"<p><a href=\"http://bar.com/foo/\" rel=\"nofollow noreferrer noopener\">foo</a></p>\n",
+
+		"[foo](/bar/)\n",
+		"<p><a href=\"/bar/\">foo</a></p>\n",
+	}
+	doTestsInlineParam(t, nofollownoreferrernoopenerTests, Options{},
+		HTML_SAFELINK|HTML_NOOPENER_LINKS|HTML_NOFOLLOW_LINKS|HTML_NOREFERRER_LINKS, HtmlRendererParameters{})
 }
 
 func TestHrefTargetBlank(t *testing.T) {