Allow the percent character in the userinfo of an authority. (#269)

The username and password in an authority are percent-encoded.

src/uri/authority.rs

@@ -91,6 +91,7 @@ impl Authority {
         let mut colon_cnt = 0;
         let mut start_bracket = false;
         let mut end_bracket = false;
+        let mut has_percent = false;
         let mut end = s.len();
         let mut at_sign_pos = None;
 
@@ -118,7 +119,17 @@ impl Authority {
                     // Those weren't a port colon, but part of the
                     // userinfo, so it needs to be forgotten.
                     colon_cnt = 0;
-
+                    has_percent = false;
+                }
+                0 if b == b'%' => {
+                    // Per https://tools.ietf.org/html/rfc3986#section-3.2.1 and
+                    // https://url.spec.whatwg.org/#authority-state
+                    // the userinfo can have a percent-encoded username and password,
+                    // so record that a `%` was found. If this turns out to be
+                    // part of the userinfo, this flag will be cleared.
+                    // If the flag hasn't been cleared at the end, that means this
+                    // was part of the hostname, and will fail with an error.
+                    has_percent = true;
                 }
                 0 => {
                     return Err(ErrorKind::InvalidUriChar.into());
@@ -141,6 +152,11 @@ impl Authority {
             return Err(ErrorKind::InvalidAuthority.into());
         }
 
+        if has_percent {
+            // Something after the userinfo has a `%`, so reject it.
+            return Err(ErrorKind::InvalidAuthority.into());
+        }
+
         Ok(end)
     }
 
@@ -564,4 +580,20 @@ mod tests {
         assert!(authority > "abc.com".to_string());
         assert!("abc.com".to_string() < authority);
     }
+
+    #[test]
+    fn allows_percent_in_userinfo() {
+        let authority_str = "a%2f:b%2f@example.com";
+        let authority: Authority = authority_str.parse().unwrap();
+        assert_eq!(authority, authority_str);
+    }
+
+    #[test]
+    fn rejects_percent_in_hostname() {
+        let err = Authority::parse_non_empty(b"example%2f.com").unwrap_err();
+        assert_eq!(err.0, ErrorKind::InvalidAuthority);
+
+        let err = Authority::parse_non_empty(b"a%2f:b%2f@example%2f.com").unwrap_err();
+        assert_eq!(err.0, ErrorKind::InvalidAuthority);
+    }
 }