Improved handling of HTTP ranges

- correct HTTP code when range syntax is invalid (fix #140)
- when multiple ranges are given, simply ignore and send whole file

Co-authored-by: Trinity Pointard <trinity.pointard@gmail.com>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/157
Reviewed-by: Alex <alex@adnab.me>
Co-authored-by: trinity-1686a <trinity.pointard@gmail.com>
Co-committed-by: trinity-1686a <trinity.pointard@gmail.com>

src/web/error.rs

@@ -1,5 +1,6 @@
 use err_derive::Error;
-use hyper::StatusCode;
+use hyper::header::HeaderValue;
+use hyper::{HeaderMap, StatusCode};
 
 use garage_util::error::Error as GarageError;
 
@@ -47,4 +48,12 @@ impl Error {
 			_ => StatusCode::BAD_REQUEST,
 		}
 	}
+
+	pub fn add_headers(&self, header_map: &mut HeaderMap<HeaderValue>) {
+		#[allow(clippy::single_match)]
+		match self {
+			Error::ApiError(e) => e.add_headers(header_map),
+			_ => (),
+		}
+	}
 }