Allow external links to start with "www.*" (#2100)

* Make www.* URLs considered valid external links

* Tweak description of is_external_link

Author: pqcfox

components/markdown/src/markdown.rs

@@ -593,6 +593,7 @@ mod tests {
     fn test_is_external_link() {
         assert!(is_external_link("http://example.com/"));
         assert!(is_external_link("https://example.com/"));
+        assert!(is_external_link("www.example.com"));
         assert!(is_external_link("https://example.com/index.html#introduction"));
 
         assert!(!is_external_link("mailto:[email protected]"));

components/utils/src/net.rs

@@ -10,7 +10,7 @@ pub fn port_is_available(port: u16) -> bool {
     TcpListener::bind(("127.0.0.1", port)).is_ok()
 }
 
-/// Returns whether a link starts with an HTTP(s) scheme.
+/// Returns whether a link starts with an HTTP(s) scheme or "www.".
 pub fn is_external_link(link: &str) -> bool {
-    link.starts_with("http:") || link.starts_with("https:")
+    link.starts_with("http:") || link.starts_with("https:") || link.starts_with("www.")
 }