feat(www): enable providers to send custom error responses via the dy…

…namic key (#1830)

* proposal: add a provider message and contact option in the dynamic key

* style/logic cleanup

* revert model changes

* fix error pass through

* error is optional

* update model and error handling

* missed these imports

* I think that's it

* revert cleanup

* revert message changes from UI

* Update access_key_serialization.ts

* Update index.ts

* Update style.css

* Update index.ts

* more feedback

* revert UI

* finish revert

* revert list item

* feedback

* don't need this anymore either

* restore SessionConfigError

* don't wrap sessionconfigerror

Makefile

@@ -7,7 +7,7 @@ GOBIND=env PATH="$(GOBIN):$(PATH)" "$(GOMOBILE)" bind
 IMPORT_HOST=github.com
 IMPORT_PATH=$(IMPORT_HOST)/Jigsaw-Code/outline-client
 
-.PHONY: android apple linux windows
+.PHONY: android apple linux windows browser
 
 all: android apple linux windows
 
@@ -73,3 +73,6 @@ $(XGO): go.mod
 go.mod: tools.go
 	go mod tidy
 	touch go.mod
+
+browser:
+	echo 'browser environment: nothing to do'

src/www/app/app.ts

@@ -218,6 +218,8 @@ export class App {
       buttonHandler = () => {
         this.showErrorDetailDialog(error);
       };
+    } else if (error instanceof errors.SessionConfigError) {
+      toastMessage = error.message;
     } else {
       const hasErrorDetails = Boolean(error.message || error.cause);
       toastMessage = this.localize('error-unexpected');

src/www/app/outline_server_repository/access_key_serialization.ts

@@ -36,8 +36,14 @@ export function staticKeyToShadowsocksSessionConfig(staticKey: string): Shadowso
   }
 }
 
-function parseShadowsocksSessionConfigJson(maybeJsonText: string): ShadowsocksSessionConfig | null {
-  const {method, password, server, server_port, prefix} = JSON.parse(maybeJsonText);
+function parseShadowsocksSessionConfigJson(responseBody: string): ShadowsocksSessionConfig | null {
+  const responseJson = JSON.parse(responseBody);
+
+  if ('error' in responseJson) {
+    throw new errors.SessionConfigError(responseJson.error.message);
+  }
+
+  const {method, password, server, server_port, prefix} = responseJson;
 
   // These are the mandatory keys.
   const missingKeys = [];
@@ -80,6 +86,10 @@ export async function fetchShadowsocksSessionConfig(configLocation: URL): Promis
 
     return parseShadowsocksSessionConfigJson(responseBody);
   } catch (cause) {
+    if (cause instanceof errors.SessionConfigError) {
+      throw cause;
+    }
+
     throw new errors.ServerAccessKeyInvalid('Failed to parse VPN information fetched from dynamic access key.', {
       cause,
     });

src/www/model/errors.ts

@@ -45,6 +45,12 @@ export class SessionConfigFetchFailed extends CustomError {
   }
 }
 
+export class SessionConfigError extends CustomError {
+  constructor(message: string) {
+    super(message);
+  }
+}
+
 export class ServerAccessKeyInvalid extends CustomError {
   constructor(message: string, options?: {cause?: Error}) {
     super(message, options);