update model and error handling

src/www/app/app.ts

@@ -599,10 +599,10 @@ export class App {
       connectionState: ServerConnectionState.DISCONNECTED,
     };
 
-    if (server.error) {
+    if (server.providerErrorResponse) {
       serverListItem.message = {
         type: 'error',
-        content: server.error,
+        content: server.providerErrorResponse.message,
       };
     }
 

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(
+  maybeJsonText: string
+): ShadowsocksSessionConfig | errors.ProviderErrorResponse | null {
+  const {method, password, server, server_port, prefix, ...rest} = JSON.parse(maybeJsonText);
+
+  if ('code' in rest && 'message' in rest) {
+    return rest as errors.ProviderErrorResponse;
+  }
 
   // These are the mandatory keys.
   const missingKeys = [];
@@ -63,7 +69,9 @@ function parseShadowsocksSessionConfigJson(maybeJsonText: string): ShadowsocksSe
 
 // fetches information from a dynamic access key and attempts to parse it
 // TODO(daniellacosse): unit tests
-export async function fetchShadowsocksSessionConfig(configLocation: URL): Promise<ShadowsocksSessionConfig> {
+export async function fetchShadowsocksSessionConfig(
+  configLocation: URL
+): Promise<ShadowsocksSessionConfig | errors.ProviderErrorResponse> {
   let response;
   try {
     response = await fetch(configLocation, {cache: 'no-store', redirect: 'follow'});
@@ -78,6 +86,10 @@ export async function fetchShadowsocksSessionConfig(configLocation: URL): Promis
       return staticKeyToShadowsocksSessionConfig(responseBody);
     }
 
+    if (responseBody.toLocaleUpperCase().includes('ERROR')) {
+      return {code: 0, message: responseBody, details: {}};
+    }
+
     return parseShadowsocksSessionConfigJson(responseBody);
   } catch (cause) {
     throw new errors.ServerAccessKeyInvalid('Failed to parse VPN information fetched from dynamic access key.', {

src/www/app/outline_server_repository/server.ts

@@ -28,6 +28,7 @@ export class OutlineServer implements Server {
   private static readonly SUPPORTED_CIPHERS = ['chacha20-ietf-poly1305', 'aes-128-gcm', 'aes-192-gcm', 'aes-256-gcm'];
 
   errorMessageId?: string;
+  providerErrorResponse?: errors.ProviderErrorResponse<{}>;
   private sessionConfig?: ShadowsocksSessionConfig;
 
   constructor(
@@ -96,7 +97,15 @@ export class OutlineServer implements Server {
 
   async connect() {
     if (this.type === ServerType.DYNAMIC_CONNECTION) {
-      this.sessionConfig = await fetchShadowsocksSessionConfig(this.sessionConfigLocation);
+      const sessionConfigOrError = await fetchShadowsocksSessionConfig(this.sessionConfigLocation);
+
+      if ('code' in sessionConfigOrError && 'message' in sessionConfigOrError) {
+        this.providerErrorResponse = sessionConfigOrError as errors.ProviderErrorResponse;
+
+        throw new errors.SessionConfigFetchFailed('Failed to fetch VPN information from dynamic access key.');
+      }
+
+      this.sessionConfig = sessionConfigOrError as ShadowsocksSessionConfig;
     }
 
     try {

src/www/model/errors.ts

@@ -15,6 +15,12 @@
 import {Server} from './server';
 import {CustomError} from '../../infrastructure/custom_error';
 
+export interface ProviderErrorResponse<T extends object = {}> {
+  code: number;
+  message: string;
+  details: T;
+}
+
 export class ServerAlreadyAdded extends CustomError {
   constructor(public readonly server: Server) {
     super();

src/www/model/server.ts

@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import {ProviderErrorResponse} from './errors';
+
 // TODO: add guidelines for this file
 
 export enum ServerType {
@@ -34,9 +36,6 @@ export interface Server {
   // The name of this server, as given by the user.
   name: string;
 
-  // Error returned pertaining to the server's status
-  error?: string;
-
   // The location to pull the session config from on each connection.
   sessionConfigLocation?: URL;
 
@@ -51,6 +50,9 @@ export interface Server {
   // must match one of the localized app message.
   errorMessageId?: string;
 
+  // Provider error returned pertaining to the server's status
+  providerErrorResponse?: ProviderErrorResponse;
+
   // Connects to the server, redirecting the device's traffic.
   connect(): Promise<void>;