Ensure authority and/or host fields are not empty (hyperium#232)

* Ensure authority and/or host fields are not empty

* Move doc comment

---------

Co-authored-by: ruben <ruben.buehler@t-online.de>

h3/src/proto/headers.rs

@@ -75,11 +75,6 @@ impl Header {
         //# request MUST contain either an :authority pseudo-header field or a
         //# Host header field.
 
-        //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1
-        //= type=TODO
-        //# If these fields are present, they MUST NOT be
-        //# empty.
-
         //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1
         //= type=TODO
         //# If the scheme does not have a mandatory authority component and none
@@ -99,6 +94,10 @@ impl Header {
 
         Ok((
             self.pseudo.method.ok_or(HeaderError::MissingMethod)?,
+            // When empty host field is built into a uri it fails
+            //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1
+            //# If these fields are present, they MUST NOT be
+            //# empty.
             uri.build().map_err(HeaderError::InvalidRequest)?,
             self.pseudo.protocol,
             self.fields,
@@ -291,6 +290,9 @@ impl Field {
 
         Ok(match name {
             b":scheme" => Field::Scheme(try_value(name, value)?),
+            //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1
+            //# If these fields are present, they MUST NOT be
+            //# empty.
             b":authority" => Field::Authority(try_value(name, value)?),
             b":path" => Field::Path(try_value(name, value)?),
             b":method" => Field::Method(
@@ -498,6 +500,38 @@ mod tests {
         );
     }
 
+    #[test]
+    fn request_has_empty_authority() {
+        //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1
+        //= type=test
+        //# If these fields are present, they MUST NOT be
+        //# empty.
+        assert_matches!(
+            Header::try_from(vec![
+                (b":method", Method::GET.as_str()).into(),
+                (b":authority", b"").into(),
+            ]),
+            Err(HeaderError::InvalidHeaderValue(_))
+        );
+    }
+
+    #[test]
+    fn request_has_empty_host() {
+        //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1
+        //= type=test
+        //# If these fields are present, they MUST NOT be
+        //# empty.
+        let headers = Header::try_from(vec![
+            (b":method", Method::GET.as_str()).into(),
+            (b"host", b"").into(),
+        ])
+        .unwrap();
+        assert_matches!(
+            headers.into_request_parts(),
+            Err(HeaderError::InvalidRequest(_))
+        );
+    }
+
     #[test]
     fn request_has_authority() {
         //= https://www.rfc-editor.org/rfc/rfc9114#section-4.3.1