More detailed error messages and moved away from deprecated error::Error::description (#54)

* Replaced deprecated error::Error description with Display

* Make OriginNotAllowed and MethodNotAllowed error messages more useful

src/lib.rs

@@ -598,9 +598,9 @@ pub enum Error {
     /// The request header `Access-Control-Request-Headers`  is required but is missing.
     MissingRequestHeaders,
     /// Origin is not allowed to make this request
-    OriginNotAllowed,
+    OriginNotAllowed(String),
     /// Requested method is not allowed
-    MethodNotAllowed,
+    MethodNotAllowed(String),
     /// One or more headers requested are not allowed
     HeadersNotAllowed,
     /// Credentials are allowed, but the Origin is set to "*". This is not allowed by W3C
@@ -620,8 +620,8 @@ impl Error {
     fn status(&self) -> Status {
         match *self {
             Error::MissingOrigin
-            | Error::OriginNotAllowed
-            | Error::MethodNotAllowed
+            | Error::OriginNotAllowed(_)
+            | Error::MethodNotAllowed(_)
             | Error::HeadersNotAllowed => Status::Forbidden,
             Error::CredentialsWithWildcardOrigin
             | Error::MissingCorsInRocketState
@@ -631,52 +631,45 @@ impl Error {
     }
 }
 
-impl error::Error for Error {
-    fn description(&self) -> &str {
-        match *self {
-            Error::MissingOrigin => "The request header `Origin` is required but is missing",
-            Error::BadOrigin(_) => "The request header `Origin` contains an invalid URL",
-            Error::MissingRequestMethod => {
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Error::MissingOrigin => write!(f, "The request header `Origin` is required but is missing"),
+            Error::BadOrigin(_) => write!(f, "The request header `Origin` contains an invalid URL"),
+            Error::MissingRequestMethod => { write!(f,
                 "The request header `Access-Control-Request-Method` \
-                 is required but is missing"
+                 is required but is missing")
             }
-            Error::BadRequestMethod => {
-                "The request header `Access-Control-Request-Method` has an invalid value"
+            Error::BadRequestMethod => { write!(f,
+                "The request header `Access-Control-Request-Method` has an invalid value")
             }
-            Error::MissingRequestHeaders => {
+            Error::MissingRequestHeaders => { write!(f,
                 "The request header `Access-Control-Request-Headers` \
-                 is required but is missing"
+                 is required but is missing")
             }
-            Error::OriginNotAllowed => "Origin is not allowed to request",
-            Error::MethodNotAllowed => "Method is not allowed",
-            Error::HeadersNotAllowed => "Headers are not allowed",
-            Error::CredentialsWithWildcardOrigin => {
+            Error::OriginNotAllowed(origin) => write!(f, "Origin '{}' is not allowed to request", &origin),
+            Error::MethodNotAllowed(method) => write!(f, "Method '{}' is not allowed", &method),
+            Error::HeadersNotAllowed => write!(f, "Headers are not allowed"),
+            Error::CredentialsWithWildcardOrigin => { write!(f,
                 "Credentials are allowed, but the Origin is set to \"*\". \
-                 This is not allowed by W3C"
+                 This is not allowed by W3C")
             }
-            Error::MissingCorsInRocketState => {
-                "A CORS Request Guard was used, but no CORS Options was available in Rocket's state"
+            Error::MissingCorsInRocketState => { write!(f,
+                "A CORS Request Guard was used, but no CORS Options was available in Rocket's state")
             }
-            Error::MissingInjectedHeader => {
+            Error::MissingInjectedHeader => write!(f,
                 "The `on_response` handler of Fairing could not find the injected header from the \
-                 Request. Either some other fairing has removed it, or this is a bug."
-            }
-        }
-    }
-
-    fn cause(&self) -> Option<&dyn error::Error> {
-        match *self {
-            Error::BadOrigin(ref e) => Some(e),
-            _ => Some(self),
+                 Request. Either some other fairing has removed it, or this is a bug.")
         }
     }
 }
 
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+
+impl error::Error for Error {
+    fn cause(&self) -> Option<&dyn error::Error> {
         match *self {
-            Error::BadOrigin(ref e) => fmt::Display::fmt(e, f),
-            _ => write!(f, "{}", error::Error::description(self)),
+            Error::BadOrigin(ref e) => Some(e),
+            _ => Some(self),
         }
     }
 }
@@ -1584,7 +1577,7 @@ fn validate_origin(
         AllOrSome::Some(ref allowed_origins) => allowed_origins
             .get(origin)
             .and_then(|_| Some(()))
-            .ok_or_else(|| Error::OriginNotAllowed),
+            .ok_or_else(|| Error::OriginNotAllowed(origin.to_string())),
     }
 }
 
@@ -1595,7 +1588,7 @@ fn validate_allowed_method(
 ) -> Result<(), Error> {
     let &AccessControlRequestMethod(ref request_method) = method;
     if !allowed_methods.iter().any(|m| m == request_method) {
-        Err(Error::MethodNotAllowed)?
+        Err(Error::MethodNotAllowed(method.0.to_string()))?
     }
 
     // TODO: Subset to route? Or just the method requested for?