Show challenge when requested by server

_locales/en/messages.json

@@ -1505,6 +1505,10 @@
     "message": "Send failed",
     "description": "Shown on outgoing message if it fails to send"
   },
+  "sendPaused": {
+    "message": "Send paused",
+    "description": "Shown on outgoing message if it cannot be sent immediately"
+  },
   "partiallySent": {
     "message": "Partially sent, click for details",
     "description": "Shown on outgoing message if it is partially sent"
@@ -5118,5 +5122,41 @@
   "ContactSpoofingReviewDialog__safe-title": {
     "message": "Your contact",
     "description": "Header in the contact spoofing review dialog, shown above the \"safe\" user"
+  },
+  "CaptchaDialog__title": {
+    "message": "Verify to continue messaging",
+    "description": "Header in the captcha dialog"
+  },
+  "CaptchaDialog__first-paragraph": {
+    "message": "To help prevent spam on Signal, please complete verification.",
+    "description": "First paragraph in the captcha dialog"
+  },
+  "CaptchaDialog__second-paragraph": {
+    "message": "After verifying, you can continue messaging. Any paused messages will automatically be sent.",
+    "description": "First paragraph in the captcha dialog"
+  },
+  "CaptchaDialog--can-close__title": {
+    "message": "Continue Without Verifying?",
+    "description": "Header in the captcha dialog that can be closed"
+  },
+  "CaptchaDialog--can-close__body": {
+    "message": "If you choose to skip verification, you may miss messages from other people and your messages may fail to send.",
+    "description": "Body of the captcha dialog that can be closed"
+  },
+  "CaptchaDialog--can_close__skip-verification": {
+    "message": "Skip verification",
+    "description": "Skip button of the captcha dialog that can be closed"
+  },
+  "verificationComplete": {
+    "message": "Verification complete.",
+    "description": "Displayed after successful captcha"
+  },
+  "verificationFailed": {
+    "message": "Verification failed. Please retry later.",
+    "description": "Displayed after unsuccessful captcha"
+  },
+  "deleteForEveryoneFailed": {
+    "message": "Failed to delete message for everyone. Please retry later.",
+    "description": "Displayed when delete-for-everyone has failed to send to all recepients"
   }
 }

main.js

@@ -108,8 +108,10 @@ const OS = require('./ts/OS');
 const { isBeta } = require('./ts/util/version');
 const {
   isSgnlHref,
+  isCaptchaHref,
   isSignalHttpsLink,
   parseSgnlHref,
+  parseCaptchaHref,
   parseSignalHttpsLink,
 } = require('./ts/util/sgnlHref');
 const {
@@ -120,8 +122,10 @@ const {
   TitleBarVisibility,
 } = require('./ts/types/Settings');
 const { Environment } = require('./ts/environment');
+const { ChallengeMainHandler } = require('./ts/main/challengeMain');
 
 const sql = new MainSQL();
+const challengeHandler = new ChallengeMainHandler();
 
 let sqlInitTimeStart = 0;
 let sqlInitTimeEnd = 0;
@@ -193,6 +197,12 @@ if (!process.mas) {
 
         showWindow();
       }
+      const incomingCaptchaHref = getIncomingCaptchaHref(argv);
+      if (incomingCaptchaHref) {
+        const { captcha } = parseCaptchaHref(incomingCaptchaHref, logger);
+        challengeHandler.handleCaptcha(captcha);
+        return true;
+      }
       // Are they trying to open a sgnl:// href?
       const incomingHref = getIncomingHref(argv);
       if (incomingHref) {
@@ -1391,11 +1401,19 @@ app.on('web-contents-created', (createEvent, contents) => {
 });
 
 app.setAsDefaultProtocolClient('sgnl');
+app.setAsDefaultProtocolClient('signalcaptcha');
 app.on('will-finish-launching', () => {
   // open-url must be set from within will-finish-launching for macOS
   // https://stackoverflow.com/a/43949291
   app.on('open-url', (event, incomingHref) => {
     event.preventDefault();
+
+    if (isCaptchaHref(incomingHref, logger)) {
+      const { captcha } = parseCaptchaHref(incomingHref, logger);
+      challengeHandler.handleCaptcha(captcha);
+      return;
+    }
+
     handleSgnlHref(incomingHref);
   });
 });
@@ -1656,6 +1674,10 @@ function getIncomingHref(argv) {
   return argv.find(arg => isSgnlHref(arg, logger));
 }
 
+function getIncomingCaptchaHref(argv) {
+  return argv.find(arg => isCaptchaHref(arg, logger));
+}
+
 function handleSgnlHref(incomingHref) {
   let command;
   let args;

package.json

@@ -367,7 +367,8 @@
     "protocols": {
       "name": "sgnl-url-scheme",
       "schemes": [
-        "sgnl"
+        "sgnl",
+        "signalcaptcha"
       ]
     },
     "asarUnpack": [

preload.js

@@ -172,6 +172,12 @@ try {
     Whisper.events.trigger('setupAsStandalone');
   });
 
+  ipc.on('challenge:response', (_event, response) => {
+    Whisper.events.trigger('challengeResponse', response);
+  });
+  window.sendChallengeRequest = request =>
+    ipc.send('challenge:request', request);
+
   {
     let isFullScreen = config.isFullScreen === 'true';
 

stylesheets/_modules.scss

@@ -297,6 +297,17 @@
     );
   }
 }
+.module-message__error--paused {
+  @include light-theme {
+    @include color-svg(
+      '../images/icons/v2/error-outline-24.svg',
+      $color-gray-60
+    );
+  }
+  @include dark-theme {
+    @include color-svg('../images/icons/v2/error-solid-24.svg', $color-gray-45);
+  }
+}
 
 .module-message__error--outgoing {
   left: 8px;
@@ -1265,6 +1276,7 @@
   margin-bottom: 2px;
 }
 
+.module-message__metadata__status-icon--paused,
 .module-message__metadata__status-icon--sending {
   animation: module-message__metadata__status-icon--spinning 4s linear infinite;
 
@@ -5254,6 +5266,10 @@ button.module-image__border-overlay:focus {
   }
 }
 
+.module-spinner__circle--on-captcha {
+  background-color: $color-white-alpha-40;
+}
+
 .module-spinner__circle--on-progress-dialog {
   @include light-theme {
     background-color: $color-white;
@@ -5268,6 +5284,9 @@ button.module-image__border-overlay:focus {
 .module-spinner__arc--on-avatar {
   background-color: $color-white;
 }
+.module-spinner__arc--on-captcha {
+  background-color: $color-white;
+}
 
 // Module: Highlighted Message Body
 
@@ -7023,6 +7042,21 @@ button.module-image__border-overlay:focus {
                   );
                 }
               }
+
+              &--paused {
+                @include light-theme {
+                  @include color-svg(
+                    '../images/icons/v2/error-outline-12.svg',
+                    $color-gray-60
+                  );
+                }
+                @include dark-theme {
+                  @include color-svg(
+                    '../images/icons/v2/error-solid-12.svg',
+                    $color-gray-45
+                  );
+                }
+              }
             }
 
             &__message-search-result-contents {

stylesheets/components/Modal.scss

@@ -39,20 +39,27 @@
     height: 24px;
     width: 24px;
 
-    @include light-theme {
+    &::before {
-      @include color-svg('../images/icons/v2/x-24.svg', $color-gray-75);
+      content: '';
-    }
+      display: block;
+      width: 100%;
+      height: 100%;
 
-    @include dark-theme {
+      @include light-theme {
-      @include color-svg('../images/icons/v2/x-24.svg', $color-gray-15);
+        @include color-svg('../images/icons/v2/x-24.svg', $color-gray-75);
-    }
-
-    &:focus {
-      @include keyboard-mode {
-        background-color: $ultramarine-ui-light;
       }
-      @include dark-keyboard-mode {
+
-        background-color: $ultramarine-ui-dark;
+      @include dark-theme {
+        @include color-svg('../images/icons/v2/x-24.svg', $color-gray-15);
+      }
+
+      &:focus {
+        @include keyboard-mode {
+          background-color: $ultramarine-ui-light;
+        }
+        @include dark-keyboard-mode {
+          background-color: $ultramarine-ui-dark;
+        }
       }
     }
   }
@@ -93,4 +100,50 @@
       margin-left: 8px;
     }
   }
+
+  // Overrides for a modal with important message
+  &--important {
+    padding: 10px 12px 16px 12px;
+
+    .module-Modal__header {
+      padding: 0;
+    }
+
+    .module-Modal__body {
+      padding: 0 12px 4px 12px !important;
+    }
+
+    .module-Modal__body p {
+      margin: 0 0 20px 0;
+    }
+
+    .module-Modal__title {
+      @include font-title-2;
+      text-align: center;
+      margin: 10px 0 22px 0;
+
+      flex-grow: 0;
+      flex-shrink: 0;
+
+      &--with-x-button {
+        margin-top: 31px;
+      }
+    }
+
+    .module-Modal__footer {
+      justify-content: center;
+      margin-top: 27px;
+      flex-grow: 0;
+      flex-shrink: 0;
+
+      .module-Button {
+        flex-grow: 1;
+        max-width: 152px;
+
+        &:not(:first-child) {
+          margin-left: 16px;
+        }
+      }
+    }
+  }
 }

ts/background.ts

@@ -5,6 +5,7 @@ import { DataMessageClass } from './textsecure.d';
 import { MessageAttributesType } from './model-types.d';
 import { WhatIsThis } from './window.d';
 import { getTitleBarVisibility, TitleBarVisibility } from './types/Settings';
+import { ChallengeHandler } from './challenge';
 import { isWindowDragElement } from './util/isWindowDragElement';
 import { assert } from './util/assert';
 import { senderCertificateService } from './services/senderCertificate';
@@ -12,6 +13,7 @@ import { routineProfileRefresh } from './routineProfileRefresh';
 import { isMoreRecentThan, isOlderThan } from './util/timestamp';
 import { isValidReactionEmoji } from './reactions/isValidReactionEmoji';
 import { ConversationModel } from './models/conversations';
+import { getMessageById } from './models/messages';
 import { createBatcher } from './util/batcher';
 import { updateConversationsWithUuidLookup } from './updateConversationsWithUuidLookup';
 import { initializeAllJobQueues } from './jobs/initializeAllJobQueues';
@@ -1439,7 +1441,62 @@ export async function startApp(): Promise<void> {
     window.textsecure.messaging.sendRequestKeySyncMessage();
   }
 
+  let challengeHandler: ChallengeHandler | undefined;
+
   async function start() {
+    challengeHandler = new ChallengeHandler({
+      storage: window.storage,
+
+      getMessageById,
+
+      requestChallenge(request) {
+        window.sendChallengeRequest(request);
+      },
+
+      async sendChallengeResponse(data) {
+        await window.textsecure.messaging.sendChallengeResponse(data);
+      },
+
+      onChallengeFailed() {
+        // TODO: DESKTOP-1530
+        // Display humanized `retryAfter`
+        window.Whisper.ToastView.show(
+          window.Whisper.CaptchaFailedToast,
+          document.getElementsByClassName('conversation-stack')[0] ||
+            document.body
+        );
+      },
+
+      onChallengeSolved() {
+        window.Whisper.ToastView.show(
+          window.Whisper.CaptchaSolvedToast,
+          document.getElementsByClassName('conversation-stack')[0] ||
+            document.body
+        );
+      },
+
+      setChallengeStatus(challengeStatus) {
+        window.reduxActions.network.setChallengeStatus(challengeStatus);
+      },
+    });
+    window.Whisper.events.on('challengeResponse', response => {
+      if (!challengeHandler) {
+        throw new Error('Expected challenge handler to be there');
+      }
+
+      challengeHandler.onResponse(response);
+    });
+
+    window.storage.onready(async () => {
+      if (!challengeHandler) {
+        throw new Error('Expected challenge handler to be there');
+      }
+
+      await challengeHandler.load();
+    });
+
+    window.Signal.challengeHandler = challengeHandler;
+
     window.dispatchEvent(new Event('storage_ready'));
 
     window.log.info('Cleanup: starting...');
@@ -1661,6 +1718,10 @@ export async function startApp(): Promise<void> {
     //   we get an online event. This waits a bit after getting an 'offline' event
     //   before disconnecting the socket manually.
     disconnectTimer = setTimeout(disconnect, 1000);
+
+    if (challengeHandler) {
+      challengeHandler.onOffline();
+    }
   }
 
   function onOnline() {
@@ -2046,6 +2107,13 @@ export async function startApp(): Promise<void> {
           );
         }
       });
+
+      if (!challengeHandler) {
+        throw new Error('Expected challenge handler to be initialized');
+      }
+
+      // Intentionally not awaiting
+      challengeHandler.onOnline();
     } finally {
       connecting = false;
     }

ts/challenge.ts

@@ -0,0 +1,485 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+/* eslint-disable no-restricted-syntax */
+
+// `ChallengeHandler` is responsible for:
+// 1. tracking the messages that failed to send with 428 error and could be
+//    retried when user solves the challenge
+// 2. presenting the challenge to user and sending the challenge response back
+//    to the server
+//
+// The tracked messages are persisted in the database, and are imported back
+// to the `ChallengeHandler` on `.load()` call (from `ts/background.ts`). They
+// are not immediately retried, however, until `.onOnline()` is called from
+// when we are actually online.
+
+import { MessageModel } from './models/messages';
+import { assert } from './util/assert';
+import { isNotNil } from './util/isNotNil';
+import { isOlderThan } from './util/timestamp';
+import { parseRetryAfter } from './util/parseRetryAfter';
+import { getEnvironment, Environment } from './environment';
+
+export type ChallengeResponse = {
+  readonly captcha: string;
+};
+
+export type IPCRequest = {
+  readonly seq: number;
+};
+
+export type IPCResponse = {
+  readonly seq: number;
+  readonly data: ChallengeResponse;
+};
+
+export enum RetryMode {
+  Retry = 'Retry',
+  NoImmediateRetry = 'NoImmediateRetry',
+}
+
+type Handler = {
+  readonly token: string | undefined;
+
+  resolve(response: ChallengeResponse): void;
+  reject(error: Error): void;
+};
+
+export type ChallengeData = {
+  readonly type: 'recaptcha';
+  readonly token: string;
+  readonly captcha: string;
+};
+
+export type MinimalMessage = Pick<
+  MessageModel,
+  'id' | 'idForLogging' | 'getLastChallengeError' | 'retrySend'
+> & {
+  isNormalBubble(): boolean;
+  get(name: 'sent_at'): number;
+  on(event: 'sent', callback: () => void): void;
+  off(event: 'sent', callback: () => void): void;
+};
+
+export type Options = {
+  readonly storage: {
+    get(key: string): ReadonlyArray<StoredEntity>;
+    put(key: string, value: ReadonlyArray<StoredEntity>): Promise<void>;
+  };
+
+  requestChallenge(request: IPCRequest): void;
+
+  getMessageById(messageId: string): Promise<MinimalMessage | undefined>;
+
+  sendChallengeResponse(data: ChallengeData): Promise<void>;
+
+  setChallengeStatus(challengeStatus: 'idle' | 'required' | 'pending'): void;
+
+  onChallengeSolved(): void;
+  onChallengeFailed(retryAfter?: number): void;
+
+  expireAfter?: number;
+};
+
+export type StoredEntity = {
+  readonly messageId: string;
+  readonly createdAt: number;
+};
+
+type TrackedEntry = {
+  readonly message: MinimalMessage;
+  readonly createdAt: number;
+};
+
+const DEFAULT_EXPIRE_AFTER = 24 * 3600 * 1000; // one day
+const MAX_RETRIES = 5;
+const CAPTCHA_URL = 'https://signalcaptchas.org/challenge/generate.html';
+const CAPTCHA_STAGING_URL =
+  'https://signalcaptchas.org/staging/challenge/generate.html';
+
+function shouldRetrySend(message: MinimalMessage): boolean {
+  const error = message.getLastChallengeError();
+  if (!error || error.retryAfter <= Date.now()) {
+    return true;
+  }
+
+  return false;
+}
+
+export function getChallengeURL(): string {
+  if (getEnvironment() === Environment.Staging) {
+    return CAPTCHA_STAGING_URL;
+  }
+  return CAPTCHA_URL;
+}
+
+// Note that even though this is a class - only one instance of
+// `ChallengeHandler` should be in memory at the same time because they could
+// overwrite each others storage data.
+export class ChallengeHandler {
+  private isLoaded = false;
+
+  private challengeToken: string | undefined;
+
+  private seq = 0;
+
+  private isOnline = false;
+
+  private readonly responseHandlers = new Map<number, Handler>();
+
+  private readonly trackedMessages = new Map<string, TrackedEntry>();
+
+  private readonly retryTimers = new Map<string, NodeJS.Timeout>();
+
+  private readonly pendingRetries = new Set<MinimalMessage>();
+
+  private readonly retryCountById = new Map<string, number>();
+
+  constructor(private readonly options: Options) {}
+
+  public async load(): Promise<void> {
+    if (this.isLoaded) {
+      return;
+    }
+
+    this.isLoaded = true;
+    const stored: ReadonlyArray<StoredEntity> =
+      this.options.storage.get('challenge:retry-message-ids') || [];
+
+    window.log.info(`challenge: loading ${stored.length} messages`);
+
+    const entityMap = new Map<string, StoredEntity>();
+    for (const entity of stored) {
+      entityMap.set(entity.messageId, entity);
+    }
+
+    const retryIds = new Set<string>(stored.map(({ messageId }) => messageId));
+
+    const maybeMessages: ReadonlyArray<
+      MinimalMessage | undefined
+    > = await Promise.all(
+      Array.from(retryIds).map(async messageId =>
+        this.options.getMessageById(messageId)
+      )
+    );
+
+    const messages: Array<MinimalMessage> = maybeMessages.filter(isNotNil);
+
+    window.log.info(`challenge: loaded ${messages.length} messages`);
+
+    await Promise.all(
+      messages.map(async message => {
+        const entity = entityMap.get(message.id);
+        if (!entity) {
+          window.log.error(
+            'challenge: unexpected missing entity ' +
+              `for ${message.idForLogging()}`
+          );
+          return;
+        }
+
+        const expireAfter = this.options.expireAfter || DEFAULT_EXPIRE_AFTER;
+        if (isOlderThan(entity.createdAt, expireAfter)) {
+          window.log.info(
+            `challenge: expired entity for ${message.idForLogging()}`
+          );
+          return;
+        }
+
+        // The initialization order is following:
+        //
+        // 1. `.load()` when the `window.storage` is ready
+        // 2. `.onOnline()` when we connected to the server
+        //
+        // Wait for `.onOnline()` to trigger the retries instead of triggering
+        // them here immediately (if the message is ready to be retried).
+        await this.register(message, RetryMode.NoImmediateRetry, entity);
+      })
+    );
+  }
+
+  public async onOffline(): Promise<void> {
+    this.isOnline = false;
+
+    window.log.info('challenge: offline');
+  }
+
+  public async onOnline(): Promise<void> {
+    this.isOnline = true;
+
+    const pending = Array.from(this.pendingRetries.values());
+    this.pendingRetries.clear();
+
+    window.log.info(`challenge: online, retrying ${pending.length} messages`);
+
+    // Retry messages that matured while we were offline
+    await Promise.all(pending.map(message => this.retryOne(message)));
+
+    await this.retrySend();
+  }
+
+  public async register(
+    message: MinimalMessage,
+    retry = RetryMode.Retry,
+    entity?: StoredEntity
+  ): Promise<void> {
+    if (this.isRegistered(message)) {
+      window.log.info(
+        `challenge: message already registered ${message.idForLogging()}`
+      );
+      return;
+    }
+
+    this.trackedMessages.set(message.id, {
+      message,
+      createdAt: entity ? entity.createdAt : Date.now(),
+    });
+    await this.persist();
+
+    // Message is already retryable - initiate new send
+    if (retry === RetryMode.Retry && shouldRetrySend(message)) {
+      window.log.info(
+        `challenge: sending message immediately ${message.idForLogging()}`
+      );
+      await this.retryOne(message);
+      return;
+    }
+
+    const error = message.getLastChallengeError();
+    if (!error) {
+      window.log.error('Unexpected message without challenge error');
+      return;
+    }
+
+    const waitTime = Math.max(0, error.retryAfter - Date.now());
+    const oldTimer = this.retryTimers.get(message.id);
+    if (oldTimer) {
+      clearTimeout(oldTimer);
+    }
+    this.retryTimers.set(
+      message.id,
+      setTimeout(() => {
+        this.retryTimers.delete(message.id);
+
+        this.retryOne(message);
+      }, waitTime)
+    );
+
+    window.log.info(
+      `challenge: tracking ${message.idForLogging()} ` +
+        `with waitTime=${waitTime}`
+    );
+
+    if (!error.data.options || !error.data.options.includes('recaptcha')) {
+      window.log.error(
+        `challenge: unexpected options ${JSON.stringify(error.data.options)}`
+      );
+    }
+
+    if (!error.data.token) {
+      window.log.error(
+        `challenge: no token in challenge error ${JSON.stringify(error.data)}`
+      );
+    } else if (message.isNormalBubble()) {
+      // Display challenge dialog only for core messages
+      // (e.g. text, attachment, embedded contact, or sticker)
+      //
+      // Note: not waiting on this call intentionally since it waits for
+      // challenge to be fully completed.
+      this.solve(error.data.token);
+    } else {
+      window.log.info(
+        `challenge: not a bubble message ${message.idForLogging()}`
+      );
+    }
+  }
+
+  public onResponse(response: IPCResponse): void {
+    const handler = this.responseHandlers.get(response.seq);
+    if (!handler) {
+      return;
+    }
+
+    this.responseHandlers.delete(response.seq);
+    handler.resolve(response.data);
+  }
+
+  public async unregister(message: MinimalMessage): Promise<void> {
+    window.log.info(`challenge: unregistered ${message.idForLogging()}`);
+    this.trackedMessages.delete(message.id);
+    this.pendingRetries.delete(message);
+
+    const timer = this.retryTimers.get(message.id);
+    this.retryTimers.delete(message.id);
+    if (timer) {
+      clearTimeout(timer);
+    }
+
+    await this.persist();
+  }
+
+  private async persist(): Promise<void> {
+    assert(
+      this.isLoaded,
+      'ChallengeHandler has to be loaded before persisting new data'
+    );
+    await this.options.storage.put(
+      'challenge:retry-message-ids',
+      Array.from(this.trackedMessages.entries()).map(
+        ([messageId, { createdAt }]) => {
+          return { messageId, createdAt };
+        }
+      )
+    );
+  }
+
+  private isRegistered(message: MinimalMessage): boolean {
+    return this.trackedMessages.has(message.id);
+  }
+
+  private async retrySend(force = false): Promise<void> {
+    window.log.info(`challenge: retrySend force=${force}`);
+
+    const retries = Array.from(this.trackedMessages.values())
+      .map(({ message }) => message)
+      // Sort messages in `sent_at` order
+      .sort((a, b) => a.get('sent_at') - b.get('sent_at'))
+      .filter(message => force || shouldRetrySend(message))
+      .map(message => this.retryOne(message));
+
+    await Promise.all(retries);
+  }
+
+  private async retryOne(message: MinimalMessage): Promise<void> {
+    // Send is already pending
+    if (!this.isRegistered(message)) {
+      return;
+    }
+
+    // We are not online
+    if (!this.isOnline) {
+      this.pendingRetries.add(message);
+      return;
+    }
+
+    const retryCount = this.retryCountById.get(message.id) || 0;
+    window.log.info(
+      `challenge: retrying sending ${message.idForLogging()}, ` +
+        `retry count: ${retryCount}`
+    );
+
+    if (retryCount === MAX_RETRIES) {
+      window.log.info(
+        `challenge: dropping message ${message.idForLogging()}, ` +
+          'too many failed retries'
+      );
+
+      // Keep the message registered so that we'll retry sending it on app
+      // restart.
+      return;
+    }
+
+    await this.unregister(message);
+
+    let sent = false;
+    const onSent = () => {
+      sent = true;
+    };
+    message.on('sent', onSent);
+
+    try {
+      await message.retrySend();
+    } catch (error) {
+      window.log.error(
+        `challenge: failed to send ${message.idForLogging()} due to ` +
+          `error: ${error && error.stack}`
+      );
+    } finally {
+      message.off('sent', onSent);
+    }
+
+    if (sent) {
+      window.log.info(`challenge: message ${message.idForLogging()} sent`);
+      this.retryCountById.delete(message.id);
+      if (this.trackedMessages.size === 0) {
+        this.options.setChallengeStatus('idle');
+      }
+    } else {
+      window.log.info(`challenge: message ${message.idForLogging()} not sent`);
+
+      this.retryCountById.set(message.id, retryCount + 1);
+      await this.register(message, RetryMode.NoImmediateRetry);
+    }
+  }
+
+  private async solve(token: string): Promise<void> {
+    const request: IPCRequest = { seq: this.seq };
+    this.seq += 1;
+
+    this.options.setChallengeStatus('required');
+    this.options.requestChallenge(request);
+
+    this.challengeToken = token || '';
+    const response = await new Promise<ChallengeResponse>((resolve, reject) => {
+      this.responseHandlers.set(request.seq, { token, resolve, reject });
+    });
+
+    // Another `.solve()` has completed earlier than us
+    if (this.challengeToken === undefined) {
+      return;
+    }
+
+    const lastToken = this.challengeToken;
+    this.challengeToken = undefined;
+
+    this.options.setChallengeStatus('pending');
+
+    window.log.info('challenge: sending challenge to server');
+
+    try {
+      await this.sendChallengeResponse({
+        type: 'recaptcha',
+        token: lastToken,
+        captcha: response.captcha,
+      });
+    } catch (error) {
+      window.log.error(
+        `challenge: challenge failure, error: ${error && error.stack}`
+      );
+      this.options.setChallengeStatus('required');
+      return;
+    }
+
+    window.log.info('challenge: challenge success. force sending');
+
+    this.options.setChallengeStatus('idle');
+
+    this.retrySend(true);
+  }
+
+  private async sendChallengeResponse(data: ChallengeData): Promise<void> {
+    try {
+      await this.options.sendChallengeResponse(data);
+    } catch (error) {
+      if (
+        !(error instanceof Error) ||
+        error.name !== 'HTTPError' ||
+        error.code !== 413 ||
+        !error.responseHeaders
+      ) {
+        this.options.onChallengeFailed();
+        throw error;
+      }
+
+      const retryAfter = parseRetryAfter(
+        error.responseHeaders['retry-after'].toString()
+      );
+
+      window.log.info(`challenge: retry after ${retryAfter}ms`);
+      this.options.onChallengeFailed(retryAfter);
+      return;
+    }
+
+    this.options.onChallengeSolved();
+  }
+}

ts/components/CaptchaDialog.stories.tsx

@@ -0,0 +1,33 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import React, { useState } from 'react';
+import { action } from '@storybook/addon-actions';
+import { boolean } from '@storybook/addon-knobs';
+import { storiesOf } from '@storybook/react';
+
+import { CaptchaDialog } from './CaptchaDialog';
+import { Button } from './Button';
+import { setup as setupI18n } from '../../js/modules/i18n';
+import enMessages from '../../_locales/en/messages.json';
+
+const story = storiesOf('Components/CaptchaDialog', module);
+
+const i18n = setupI18n('en', enMessages);
+
+story.add('CaptchaDialog', () => {
+  const [isSkipped, setIsSkipped] = useState(false);
+
+  if (isSkipped) {
+    return <Button onClick={() => setIsSkipped(false)}>Show again</Button>;
+  }
+
+  return (
+    <CaptchaDialog
+      i18n={i18n}
+      isPending={boolean('isPending', false)}
+      onContinue={action('onContinue')}
+      onSkip={() => setIsSkipped(true)}
+    />
+  );
+});

ts/components/CaptchaDialog.tsx

@@ -0,0 +1,99 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import React, { useRef, useState } from 'react';
+
+import { LocalizerType } from '../types/Util';
+import { Button, ButtonVariant } from './Button';
+import { Modal } from './Modal';
+import { Spinner } from './Spinner';
+
+type PropsType = {
+  i18n: LocalizerType;
+  isPending: boolean;
+
+  onContinue: () => void;
+  onSkip: () => void;
+};
+
+export function CaptchaDialog(props: Readonly<PropsType>): JSX.Element {
+  const { i18n, isPending, onSkip, onContinue } = props;
+
+  const [isClosing, setIsClosing] = useState(false);
+
+  const buttonRef = useRef<HTMLButtonElement | null>(null);
+
+  const onCancelClick = (event: React.MouseEvent) => {
+    event.preventDefault();
+    setIsClosing(false);
+  };
+
+  const onSkipClick = (event: React.MouseEvent) => {
+    event.preventDefault();
+    onSkip();
+  };
+
+  if (isClosing && !isPending) {
+    return (
+      <Modal
+        moduleClassName="module-Modal"
+        i18n={i18n}
+        title={i18n('CaptchaDialog--can-close__title')}
+      >
+        <section>
+          <p>{i18n('CaptchaDialog--can-close__body')}</p>
+        </section>
+        <Modal.Footer>
+          <Button onClick={onCancelClick} variant={ButtonVariant.Secondary}>
+            {i18n('cancel')}
+          </Button>
+          <Button onClick={onSkipClick} variant={ButtonVariant.Destructive}>
+            {i18n('CaptchaDialog--can_close__skip-verification')}
+          </Button>
+        </Modal.Footer>
+      </Modal>
+    );
+  }
+
+  const onContinueClick = (event: React.MouseEvent) => {
+    event.preventDefault();
+
+    onContinue();
+  };
+
+  const updateButtonRef = (button: HTMLButtonElement): void => {
+    buttonRef.current = button;
+    if (button) {
+      button.focus();
+    }
+  };
+
+  return (
+    <Modal
+      moduleClassName="module-Modal--important"
+      i18n={i18n}
+      title={i18n('CaptchaDialog__title')}
+      hasXButton
+      onClose={() => setIsClosing(true)}
+    >
+      <section>
+        <p>{i18n('CaptchaDialog__first-paragraph')}</p>
+        <p>{i18n('CaptchaDialog__second-paragraph')}</p>
+      </section>
+      <Modal.Footer>
+        <Button
+          disabled={isPending}
+          onClick={onContinueClick}
+          ref={updateButtonRef}
+          variant={ButtonVariant.Primary}
+        >
+          {isPending ? (
+            <Spinner size="22px" svgSize="small" direction="on-captcha" />
+          ) : (
+            'Continue'
+          )}
+        </Button>
+      </Modal.Footer>
+    </Modal>
+  );
+}

ts/components/LeftPane.stories.tsx

@@ -4,9 +4,11 @@
 import * as React from 'react';
 
 import { action } from '@storybook/addon-actions';
+import { select } from '@storybook/addon-knobs';
 import { storiesOf } from '@storybook/react';
 
 import { LeftPane, LeftPaneMode, PropsType } from './LeftPane';
+import { CaptchaDialog } from './CaptchaDialog';
 import { PropsData as ConversationListItemPropsType } from './conversationList/ConversationListItem';
 import { MessageSearchResult } from './conversationList/MessageSearchResult';
 import { setup as setupI18n } from '../../js/modules/i18n';
@@ -106,6 +108,12 @@ const createProps = (overrideProps: Partial<PropsType> = {}): PropsType => ({
   modeSpecificProps: defaultModeSpecificProps,
   openConversationInternal: action('openConversationInternal'),
   regionCode: 'US',
+  challengeStatus: select(
+    'challengeStatus',
+    ['idle', 'required', 'pending'],
+    'idle'
+  ),
+  setChallengeStatus: action('setChallengeStatus'),
   renderExpiredBuildDialog: () => <div />,
   renderMainHeader: () => <div />,
   renderMessageSearchResult: (id: string, style: React.CSSProperties) => (
@@ -126,6 +134,14 @@ const createProps = (overrideProps: Partial<PropsType> = {}): PropsType => ({
   renderNetworkStatus: () => <div />,
   renderRelinkDialog: () => <div />,
   renderUpdateDialog: () => <div />,
+  renderCaptchaDialog: () => (
+    <CaptchaDialog
+      i18n={i18n}
+      isPending={overrideProps.challengeStatus === 'pending'}
+      onContinue={action('onCaptchaContinue')}
+      onSkip={action('onCaptchaSkip')}
+    />
+  ),
   selectedConversationId: undefined,
   selectedMessageId: undefined,
   setComposeSearchTerm: action('setComposeSearchTerm'),
@@ -468,3 +484,33 @@ story.add('Compose: some contacts, some groups, with a search term', () => (
     })}
   />
 ));
+
+// Captcha flow
+
+story.add('Captcha dialog: required', () => (
+  <LeftPane
+    {...createProps({
+      modeSpecificProps: {
+        mode: LeftPaneMode.Inbox,
+        pinnedConversations,
+        conversations: defaultConversations,
+        archivedConversations: [],
+      },
+      challengeStatus: 'required',
+    })}
+  />
+));
+
+story.add('Captcha dialog: pending', () => (
+  <LeftPane
+    {...createProps({
+      modeSpecificProps: {
+        mode: LeftPaneMode.Inbox,
+        pinnedConversations,
+        conversations: defaultConversations,
+        archivedConversations: [],
+      },
+      challengeStatus: 'pending',
+    })}
+  />
+));

ts/components/LeftPane.tsx

@@ -79,6 +79,8 @@ export type PropsType = {
   selectedConversationId: undefined | string;
   selectedMessageId: undefined | string;
   regionCode: string;
+  challengeStatus: 'idle' | 'required' | 'pending';
+  setChallengeStatus: (status: 'idle') => void;
 
   // Action Creators
   cantAddContactToGroup: (conversationId: string) => void;
@@ -110,6 +112,7 @@ export type PropsType = {
   renderNetworkStatus: () => JSX.Element;
   renderRelinkDialog: () => JSX.Element;
   renderUpdateDialog: () => JSX.Element;
+  renderCaptchaDialog: (props: { onSkip(): void }) => JSX.Element;
 };
 
 export const LeftPane: React.FC<PropsType> = ({
@@ -121,6 +124,8 @@ export const LeftPane: React.FC<PropsType> = ({
   createGroup,
   i18n,
   modeSpecificProps,
+  challengeStatus,
+  setChallengeStatus,
   openConversationInternal,
   renderExpiredBuildDialog,
   renderMainHeader,
@@ -128,6 +133,7 @@ export const LeftPane: React.FC<PropsType> = ({
   renderNetworkStatus,
   renderRelinkDialog,
   renderUpdateDialog,
+  renderCaptchaDialog,
   selectedConversationId,
   selectedMessageId,
   setComposeSearchTerm,
@@ -464,6 +470,12 @@ export const LeftPane: React.FC<PropsType> = ({
       {footerContents && (
         <div className="module-left-pane__footer">{footerContents}</div>
       )}
+      {challengeStatus !== 'idle' &&
+        renderCaptchaDialog({
+          onSkip() {
+            setChallengeStatus('idle');
+          },
+        })}
     </div>
   );
 };

ts/components/MainHeader.tsx

@@ -32,6 +32,7 @@ export type PropsType = {
   isMe?: boolean;
   name?: string;
   color?: ColorType;
+  disabled?: boolean;
   isVerified?: boolean;
   profileName?: string;
   title: string;
@@ -339,6 +340,7 @@ export class MainHeader extends React.Component<PropsType, StateType> {
     const {
       avatarPath,
       color,
+      disabled,
       i18n,
       name,
       startComposing,
@@ -437,6 +439,7 @@ export class MainHeader extends React.Component<PropsType, StateType> {
             />
           )}
           <input
+            disabled={disabled}
             type="text"
             ref={this.inputRef}
             className={classNames(

ts/components/Modal.tsx

@@ -48,12 +48,22 @@ export function Modal({
                 aria-label={i18n('close')}
                 type="button"
                 className="module-Modal__close-button"
+                tabIndex={0}
                 onClick={() => {
                   onClose();
                 }}
               />
             )}
-            {title && <h1 className="module-Modal__title">{title}</h1>}
+            {title && (
+              <h1
+                className={classNames(
+                  'module-Modal__title',
+                  hasXButton ? 'module-Modal__title--with-x-button' : null
+                )}
+              >
+                {title}
+              </h1>
+            )}
           </div>
         )}
         <div

ts/components/NetworkStatus.stories.tsx

@@ -19,6 +19,7 @@ const defaultProps = {
   socketStatus: 0,
   manualReconnect: action('manual-reconnect'),
   withinConnectingGracePeriod: false,
+  challengeStatus: 'idle' as const,
 };
 
 const permutations = [

ts/components/Spinner.tsx

@@ -11,6 +11,7 @@ export const SpinnerDirections = [
   'outgoing',
   'incoming',
   'on-background',
+  'on-captcha',
   'on-progress-dialog',
   'on-avatar',
 ] as const;

ts/components/conversation/Message.stories.tsx

@@ -489,6 +489,15 @@ story.add('Error', () => {
   return renderBothDirections(props);
 });
 
+story.add('Paused', () => {
+  const props = createProps({
+    status: 'paused',
+    text: 'I am up to a challenge',
+  });
+
+  return renderBothDirections(props);
+});
+
 story.add('Partial Send', () => {
   const props = createProps({
     status: 'partial-sent',

ts/components/conversation/Message.tsx

@@ -67,6 +67,7 @@ const THREE_HOURS = 3 * 60 * 60 * 1000;
 export const MessageStatuses = [
   'delivered',
   'error',
+  'paused',
   'partial-sent',
   'read',
   'sending',
@@ -522,8 +523,31 @@ export class Message extends React.Component<Props, State> {
     const isError = status === 'error' && direction === 'outgoing';
     const isPartiallySent =
       status === 'partial-sent' && direction === 'outgoing';
+    const isPaused = status === 'paused';
+
+    if (isError || isPartiallySent || isPaused) {
+      let statusInfo: React.ReactChild;
+      if (isError) {
+        statusInfo = i18n('sendFailed');
+      } else if (isPaused) {
+        statusInfo = i18n('sendPaused');
+      } else {
+        statusInfo = (
+          <button
+            type="button"
+            className="module-message__metadata__tapable"
+            onClick={(event: React.MouseEvent) => {
+              event.stopPropagation();
+              event.preventDefault();
+
+              showMessageDetail(id);
+            }}
+          >
+            {i18n('partiallySent')}
+          </button>
+        );
+      }
 
-    if (isError || isPartiallySent) {
       return (
         <span
           className={classNames({
@@ -533,22 +557,7 @@ export class Message extends React.Component<Props, State> {
             'module-message__metadata__date--with-image-no-caption': withImageNoCaption,
           })}
         >
-          {isError ? (
+          {statusInfo}
-            i18n('sendFailed')
-          ) : (
-            <button
-              type="button"
-              className="module-message__metadata__tapable"
-              onClick={(event: React.MouseEvent) => {
-                event.stopPropagation();
-                event.preventDefault();
-
-                showMessageDetail(id);
-              }}
-            >
-              {i18n('partiallySent')}
-            </button>
-          )}
         </span>
       );
     }
@@ -1232,7 +1241,15 @@ export class Message extends React.Component<Props, State> {
   public renderError(isCorrectSide: boolean): JSX.Element | null {
     const { status, direction } = this.props;
 
-    if (!isCorrectSide || (status !== 'error' && status !== 'partial-sent')) {
+    if (!isCorrectSide) {
+      return null;
+    }
+
+    if (
+      status !== 'paused' &&
+      status !== 'error' &&
+      status !== 'partial-sent'
+    ) {
       return null;
     }
 
@@ -1241,7 +1258,8 @@ export class Message extends React.Component<Props, State> {
         <div
           className={classNames(
             'module-message__error',
-            `module-message__error--${direction}`
+            `module-message__error--${direction}`,
+            `module-message__error--${status}`
           )}
         />
       </div>
@@ -1446,7 +1464,9 @@ export class Message extends React.Component<Props, State> {
     const { canDeleteForEveryone } = this.state;
 
     const showRetry =
-      (status === 'error' || status === 'partial-sent') &&
+      (status === 'paused' ||
+        status === 'error' ||
+        status === 'partial-sent') &&
       direction === 'outgoing';
     const multipleAttachments = attachments && attachments.length > 1;
 

ts/components/conversationList/ConversationListItem.tsx

@@ -27,6 +27,7 @@ export const MessageStatuses = [
   'sent',
   'delivered',
   'read',
+  'paused',
   'error',
   'partial-sent',
 ] as const;

ts/main/challengeMain.ts

@@ -0,0 +1,50 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+/* eslint-disable no-restricted-syntax, no-console */
+
+import { ipcMain as ipc, IpcMainEvent } from 'electron';
+
+import { IPCRequest, IPCResponse, ChallengeResponse } from '../challenge';
+
+export class ChallengeMainHandler {
+  private handlers: Array<(response: ChallengeResponse) => void> = [];
+
+  constructor() {
+    this.initialize();
+  }
+
+  public handleCaptcha(captcha: string): void {
+    const response: ChallengeResponse = { captcha };
+
+    const { handlers } = this;
+    this.handlers = [];
+    for (const resolve of handlers) {
+      resolve(response);
+    }
+  }
+
+  private async onRequest(
+    event: IpcMainEvent,
+    request: IPCRequest
+  ): Promise<void> {
+    console.log('Received challenge request, waiting for response');
+
+    const data = await new Promise<ChallengeResponse>(resolve => {
+      this.handlers.push(resolve);
+    });
+
+    console.log('Sending challenge response', data);
+
+    const ipcResponse: IPCResponse = {
+      seq: request.seq,
+      data,
+    };
+    event.sender.send('challenge:response', ipcResponse);
+  }
+
+  private initialize(): void {
+    ipc.on('challenge:request', (event, request) => {
+      this.onRequest(event, request);
+    });
+  }
+}

ts/model-types.d.ts

@@ -13,6 +13,7 @@ import {
   LastMessageStatus,
 } from './state/ducks/conversations';
 import { SendOptionsType } from './textsecure/SendMessage';
+import { SendMessageChallengeData } from './textsecure/Errors';
 import {
   AccessRequiredEnum,
   MemberRoleEnum,
@@ -42,6 +43,8 @@ type TaskResultType = any;
 export type CustomError = Error & {
   identifier?: string;
   number?: string;
+  data?: object;
+  retryAfter?: number;
 };
 
 export type GroupMigrationType = {
@@ -62,6 +65,13 @@ export type QuotedMessageType = {
   text: string;
 };
 
+export type RetryOptions = Readonly<{
+  type: 'session-reset';
+  uuid: string;
+  e164: string;
+  now: number;
+}>;
+
 export type MessageAttributesType = {
   bodyPending: boolean;
   bodyRanges: BodyRangesType;
@@ -113,6 +123,7 @@ export type MessageAttributesType = {
   }>;
   read_by: Array<string | null>;
   requiredProtocolVersion: number;
+  retryOptions?: RetryOptions;
   sent: boolean;
   sourceDevice: string | number;
   snippet: unknown;
@@ -325,6 +336,11 @@ export type VerificationOptions = {
   viaSyncMessage?: boolean;
 };
 
+export type ShallowChallengeError = CustomError & {
+  readonly retryAfter: number;
+  readonly data: SendMessageChallengeData;
+};
+
 export declare class ConversationModelCollectionType extends Backbone.Collection<ConversationModel> {
   resetLookups(): void;
 }

ts/models/conversations.ts

@@ -3028,8 +3028,6 @@ export class ConversationModel extends window.Backbone
       fromId: window.ConversationController.getOurConversationId(),
     });
 
-    window.Whisper.Deletes.onDelete(deleteModel);
-
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     const destination = this.getSendTarget()!;
     const recipients = this.getRecipients();
@@ -3108,7 +3106,16 @@ export class ConversationModel extends window.Backbone
       //   anything to the database.
       message.doNotSave = true;
 
-      return message.send(this.wrapSend(promise));
+      const result = await message.send(this.wrapSend(promise));
+
+      if (!message.hasSuccessfulDelivery()) {
+        // This is handled by `conversation_view` which displays a toast on
+        // send error.
+        throw new Error('No successful delivery for delete for everyone');
+      }
+      window.Whisper.Deletes.onDelete(deleteModel);
+
+      return result;
     }).catch(error => {
       window.log.error(
         'Error sending deleteForEveryone',
@@ -3138,7 +3145,6 @@ export class ConversationModel extends window.Backbone
       timestamp,
       fromSync: true,
     });
-    window.Whisper.Reactions.onReaction(reactionModel);
 
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     const destination = this.getSendTarget()!;
@@ -3239,15 +3245,17 @@ export class ConversationModel extends window.Backbone
         );
       })();
 
-      return message.send(this.wrapSend(promise));
+      const result = await message.send(this.wrapSend(promise));
-    }).catch(error => {
-      window.log.error('Error sending reaction', reaction, target, error);
 
-      const reverseReaction = reactionModel.clone();
+      if (!message.hasSuccessfulDelivery()) {
-      reverseReaction.set('remove', !reverseReaction.get('remove'));
+        // This is handled by `conversation_view` which displays a toast on
-      window.Whisper.Reactions.onReaction(reverseReaction);
+        // send error.
+        throw new Error('No successful delivery for reaction');
+      }
 
-      throw error;
+      window.Whisper.Reactions.onReaction(reactionModel);
+
+      return result;
     });
   }
 
@@ -4167,25 +4175,17 @@ export class ConversationModel extends window.Backbone
       const message = window.MessageController.register(model.id, model);
       this.addSingleMessage(message);
 
-      const options = await this.getSendOptions();
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-      message.send(
+      const uuid = this.get('uuid')!;
-        this.wrapSend(
+      // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-          // TODO: DESKTOP-724
+      const e164 = this.get('e164')!;
-          // resetSession returns `Array<void>` which is incompatible with the
+
-          // expected promise return values. `[]` is truthy and wrapSend assumes
+      message.sendUtilityMessageWithRetry({
-          // it's a valid callback result type
+        type: 'session-reset',
-          // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+        uuid,
-          // @ts-ignore
+        e164,
-          window.textsecure.messaging.resetSession(
+        now,
-            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+      });
-            this.get('uuid')!,
-            // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-            this.get('e164')!,
-            now,
-            options
-          )
-        )
-      );
     }
   }
 

ts/models/messages.ts

@@ -4,6 +4,8 @@
 import {
   CustomError,
   MessageAttributesType,
+  RetryOptions,
+  ShallowChallengeError,
   QuotedMessageType,
   WhatIsThis,
 } from '../model-types.d';
@@ -1041,6 +1043,9 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
     const sentTo = this.get('sent_to') || [];
 
     if (this.hasErrors()) {
+      if (this.getLastChallengeError()) {
+        return 'paused';
+      }
       if (sent || sentTo.length > 0) {
         return 'partial-sent';
       }
@@ -2000,6 +2005,8 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
           'code',
           'number',
           'identifier',
+          'retryAfter',
+          'data',
           'reason'
         ) as Required<Error>;
       }
@@ -2009,6 +2016,13 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
 
     this.set({ errors });
 
+    if (
+      !this.doNotSave &&
+      errors.some(error => error.name === 'SendMessageChallengeError')
+    ) {
+      await window.Signal.challengeHandler.register(this);
+    }
+
     if (!skipSave && !this.doNotSave) {
       await window.Signal.Data.saveMessage(this.attributes, {
         Message: window.Whisper.Message,
@@ -2109,7 +2123,13 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
       return null;
     }
 
-    this.set({ errors: undefined });
+    const retryOptions = this.get('retryOptions');
+
+    this.set({ errors: undefined, retryOptions: undefined });
+
+    if (retryOptions) {
+      return this.sendUtilityMessageWithRetry(retryOptions);
+    }
 
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     const conversation = this.getConversation()!;
@@ -2252,11 +2272,35 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
       e.name === 'MessageError' ||
       e.name === 'OutgoingMessageError' ||
       e.name === 'SendMessageNetworkError' ||
+      e.name === 'SendMessageChallengeError' ||
       e.name === 'SignedPreKeyRotationError' ||
       e.name === 'OutgoingIdentityKeyError'
     );
   }
 
+  public getLastChallengeError(): ShallowChallengeError | undefined {
+    const errors: ReadonlyArray<CustomError> | undefined = this.get('errors');
+    if (!errors) {
+      return undefined;
+    }
+
+    const challengeErrors = errors
+      .filter((error): error is ShallowChallengeError => {
+        return (
+          error.name === 'SendMessageChallengeError' &&
+          _.isNumber(error.retryAfter) &&
+          _.isObject(error.data)
+        );
+      })
+      .sort((a, b) => a.retryAfter - b.retryAfter);
+
+    return challengeErrors.pop();
+  }
+
+  public hasSuccessfulDelivery(): boolean {
+    return (this.get('sent_to') || []).length !== 0;
+  }
+
   canDeleteForEveryone(): boolean {
     // is someone else's message
     if (this.isIncoming()) {
@@ -2423,6 +2467,7 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
         (e.name === 'MessageError' ||
           e.name === 'OutgoingMessageError' ||
           e.name === 'SendMessageNetworkError' ||
+          e.name === 'SendMessageChallengeError' ||
           e.name === 'SignedPreKeyRotationError' ||
           e.name === 'OutgoingIdentityKeyError')
     );
@@ -2564,6 +2609,59 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
       });
   }
 
+  // Currently used only for messages that have to be retried when the server
+  // responds with 428 and we have to retry sending the message on challenge
+  // solution.
+  //
+  // Supported types of messages:
+  // * `session-reset` see `endSession` in `ts/models/conversations.ts`
+  async sendUtilityMessageWithRetry(options: RetryOptions): Promise<void> {
+    if (options.type === 'session-reset') {
+      const conv = this.getConversation();
+      if (!conv) {
+        throw new Error(
+          `Failed to find conversation for message: ${this.idForLogging()}`
+        );
+      }
+      if (!window.textsecure.messaging) {
+        throw new Error('Offline');
+      }
+
+      this.set({
+        retryOptions: options,
+      });
+
+      const sendOptions = await conv.getSendOptions();
+
+      // We don't have to check `sent_to` here, because:
+      //
+      // 1. This happens only in private conversations
+      // 2. Messages to different device ids for the same identifier are sent
+      //    in a single request to the server. So partial success is not
+      //    possible.
+      await this.send(
+        conv.wrapSend(
+          // TODO: DESKTOP-724
+          // resetSession returns `Array<void>` which is incompatible with the
+          // expected promise return values. `[]` is truthy and wrapSend assumes
+          // it's a valid callback result type
+          // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+          // @ts-ignore
+          window.textsecure.messaging.resetSession(
+            options.uuid,
+            options.e164,
+            options.now,
+            sendOptions
+          )
+        )
+      );
+
+      return;
+    }
+
+    throw new Error(`Unsupported retriable type: ${options.type}`);
+  }
+
   async sendSyncMessageOnly(dataMessage: ArrayBuffer): Promise<void> {
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     const conv = this.getConversation()!;
@@ -2590,7 +2688,7 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
       });
     } catch (result) {
       const errors = (result && result.errors) || [new Error('Unknown error')];
-      this.set({ errors });
+      this.saveErrors(errors);
     } finally {
       await window.Signal.Data.saveMessage(this.attributes, {
         Message: window.Whisper.Message,
@@ -4094,6 +4192,33 @@ export class MessageModel extends window.Backbone.Model<MessageAttributesType> {
   }
 }
 
+export async function getMessageById(
+  messageId: string
+): Promise<MessageModel | undefined> {
+  let message = window.MessageController.getById(messageId);
+  if (message) {
+    return message;
+  }
+
+  try {
+    message = await window.Signal.Data.getMessageById(messageId, {
+      Message: window.Whisper.Message,
+    });
+  } catch (error) {
+    window.log.error(
+      `failed to load message with id ${messageId} ` +
+        `due to error ${error && error.stack}`
+    );
+  }
+
+  if (!message) {
+    return undefined;
+  }
+
+  message = window.MessageController.register(message.id, message);
+  return message;
+}
+
 window.Whisper.Message = MessageModel;
 
 window.Whisper.Message.getLongMessageAttachment = ({

ts/state/ducks/conversations.ts

@@ -42,6 +42,7 @@ export type DBConversationType = {
 };
 
 export type LastMessageStatus =
+  | 'paused'
   | 'error'
   | 'partial-sent'
   | 'sending'

ts/state/ducks/network.ts

@@ -11,6 +11,7 @@ export type NetworkStateType = {
   isOnline: boolean;
   socketStatus: SocketStatus;
   withinConnectingGracePeriod: boolean;
+  challengeStatus: 'required' | 'pending' | 'idle';
 };
 
 // Actions
@@ -18,6 +19,7 @@ export type NetworkStateType = {
 const CHECK_NETWORK_STATUS = 'network/CHECK_NETWORK_STATUS';
 const CLOSE_CONNECTING_GRACE_PERIOD = 'network/CLOSE_CONNECTING_GRACE_PERIOD';
 const RELINK_DEVICE = 'network/RELINK_DEVICE';
+const SET_CHALLENGE_STATUS = 'network/SET_CHALLENGE_STATUS';
 
 export type CheckNetworkStatusPayloadType = {
   isOnline: boolean;
@@ -37,10 +39,18 @@ type RelinkDeviceActionType = {
   type: 'network/RELINK_DEVICE';
 };
 
+type SetChallengeStatusActionType = {
+  type: 'network/SET_CHALLENGE_STATUS';
+  payload: {
+    challengeStatus: NetworkStateType['challengeStatus'];
+  };
+};
+
 export type NetworkActionType =
   | CheckNetworkStatusAction
   | CloseConnectingGracePeriodActionType
-  | RelinkDeviceActionType;
+  | RelinkDeviceActionType
+  | SetChallengeStatusActionType;
 
 // Action Creators
 
@@ -67,19 +77,30 @@ function relinkDevice(): RelinkDeviceActionType {
   };
 }
 
+function setChallengeStatus(
+  challengeStatus: NetworkStateType['challengeStatus']
+): SetChallengeStatusActionType {
+  return {
+    type: SET_CHALLENGE_STATUS,
+    payload: { challengeStatus },
+  };
+}
+
 export const actions = {
   checkNetworkStatus,
   closeConnectingGracePeriod,
   relinkDevice,
+  setChallengeStatus,
 };
 
 // Reducer
 
-function getEmptyState(): NetworkStateType {
+export function getEmptyState(): NetworkStateType {
   return {
     isOnline: navigator.onLine,
     socketStatus: WebSocket.OPEN,
     withinConnectingGracePeriod: true,
+    challengeStatus: 'idle',
   };
 }
 
@@ -105,5 +126,12 @@ export function reducer(
     };
   }
 
+  if (action.type === SET_CHALLENGE_STATUS) {
+    return {
+      ...state,
+      challengeStatus: action.payload.challengeStatus,
+    };
+  }
+
   return state;
 }

ts/state/selectors/network.ts

@@ -22,3 +22,8 @@ export const hasNetworkDialog = createSelector(
       socketStatus === WebSocket.CLOSED ||
       socketStatus === WebSocket.CLOSING)
 );
+
+export const isChallengePending = createSelector(
+  getNetwork,
+  ({ challengeStatus }) => challengeStatus === 'pending'
+);

ts/state/smart/CaptchaDialog.tsx

@@ -0,0 +1,26 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { connect } from 'react-redux';
+import { mapDispatchToProps } from '../actions';
+import { CaptchaDialog } from '../../components/CaptchaDialog';
+import { StateType } from '../reducer';
+import { getIntl } from '../selectors/user';
+import { isChallengePending } from '../selectors/network';
+import { getChallengeURL } from '../../challenge';
+
+const mapStateToProps = (state: StateType) => {
+  return {
+    ...state.updates,
+    isPending: isChallengePending(state),
+    i18n: getIntl(state),
+
+    onContinue() {
+      document.location.href = getChallengeURL();
+    },
+  };
+};
+
+const smart = connect(mapStateToProps, mapDispatchToProps);
+
+export const SmartCaptchaDialog = smart(CaptchaDialog);

ts/state/smart/LeftPane.tsx

@@ -41,6 +41,7 @@ import { SmartMessageSearchResult } from './MessageSearchResult';
 import { SmartNetworkStatus } from './NetworkStatus';
 import { SmartRelinkDialog } from './RelinkDialog';
 import { SmartUpdateDialog } from './UpdateDialog';
+import { SmartCaptchaDialog } from './CaptchaDialog';
 
 // Workaround: A react component's required properties are filtering up through connect()
 //   https://github.com/DefinitelyTyped/DefinitelyTyped/issues/31363
@@ -69,6 +70,9 @@ function renderRelinkDialog(): JSX.Element {
 function renderUpdateDialog(): JSX.Element {
   return <SmartUpdateDialog />;
 }
+function renderCaptchaDialog({ onSkip }: { onSkip(): void }): JSX.Element {
+  return <SmartCaptchaDialog onSkip={onSkip} />;
+}
 
 const getModeSpecificProps = (
   state: StateType
@@ -136,12 +140,14 @@ const mapStateToProps = (state: StateType) => {
     showArchived: getShowArchived(state),
     i18n: getIntl(state),
     regionCode: getRegionCode(state),
+    challengeStatus: state.network.challengeStatus,
     renderExpiredBuildDialog,
     renderMainHeader,
     renderMessageSearchResult,
     renderNetworkStatus,
     renderRelinkDialog,
     renderUpdateDialog,
+    renderCaptchaDialog,
   };
 };
 

ts/state/smart/MainHeader.tsx

@@ -24,6 +24,7 @@ import { getMe, getSelectedConversation } from '../selectors/conversations';
 
 const mapStateToProps = (state: StateType) => {
   return {
+    disabled: state.network.challengeStatus !== 'idle',
     searchTerm: getQuery(state),
     searchConversationId: getSearchConversationId(state),
     searchConversationName: getSearchConversationName(state),

ts/test-both/challenge_test.ts

@@ -0,0 +1,382 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+/* eslint-disable no-await-in-loop, no-restricted-syntax */
+/* eslint-disable @typescript-eslint/no-explicit-any */
+
+import { assert } from 'chai';
+import { noop } from 'lodash';
+import * as sinon from 'sinon';
+
+import { sleep } from '../util/sleep';
+import { ChallengeHandler, MinimalMessage } from '../challenge';
+
+type CreateMessageOptions = {
+  readonly sentAt?: number;
+  readonly retryAfter?: number;
+  readonly isNormalBubble?: boolean;
+};
+
+type CreateHandlerOptions = {
+  readonly challenge?: boolean;
+  readonly challengeError?: Error;
+  readonly expireAfter?: number;
+  readonly onChallengeSolved?: () => void;
+  readonly onChallengeFailed?: (retryAfter?: number) => void;
+};
+
+describe('ChallengeHandler', () => {
+  const storage = new Map<string, any>();
+  const messageStorage = new Map<string, MinimalMessage>();
+  let challengeStatus = 'idle';
+  let sent: Array<string> = [];
+
+  beforeEach(() => {
+    storage.clear();
+    messageStorage.clear();
+    challengeStatus = 'idle';
+    sent = [];
+  });
+
+  const createMessage = (
+    id: string,
+    options: CreateMessageOptions = {}
+  ): MinimalMessage => {
+    const {
+      sentAt = 0,
+      isNormalBubble = true,
+      retryAfter = Date.now() + 25,
+    } = options;
+
+    const testLocalSent = sent;
+
+    const events = new Map<string, () => void>();
+
+    return {
+      id,
+      idForLogging: () => id,
+      isNormalBubble() {
+        return isNormalBubble;
+      },
+      getLastChallengeError() {
+        return {
+          name: 'Ignored',
+          message: 'Ignored',
+          retryAfter,
+          data: { token: 'token', options: ['recaptcha'] },
+        };
+      },
+      get(name) {
+        assert.equal(name, 'sent_at');
+        return sentAt;
+      },
+      on(name, handler) {
+        if (events.get(name)) {
+          throw new Error('Duplicate event');
+        }
+        events.set(name, handler);
+      },
+      off(name, handler) {
+        assert.equal(events.get(name), handler);
+        events.delete(name);
+      },
+      async retrySend() {
+        await sleep(5);
+        const handler = events.get('sent');
+        if (!handler) {
+          throw new Error('Expected handler');
+        }
+        handler();
+        testLocalSent.push(this.id);
+      },
+    };
+  };
+
+  const createHandler = async ({
+    challenge = false,
+    challengeError,
+    expireAfter,
+    onChallengeSolved = noop,
+    onChallengeFailed = noop,
+  }: CreateHandlerOptions = {}): Promise<ChallengeHandler> => {
+    const handler = new ChallengeHandler({
+      expireAfter,
+
+      storage: {
+        get(key) {
+          return storage.get(key);
+        },
+        async put(key, value) {
+          storage.set(key, value);
+        },
+      },
+
+      onChallengeSolved,
+      onChallengeFailed,
+
+      requestChallenge(request) {
+        if (!challenge) {
+          return;
+        }
+
+        setTimeout(() => {
+          handler.onResponse({
+            seq: request.seq,
+            data: { captcha: 'captcha' },
+          });
+        }, 5);
+      },
+
+      async getMessageById(messageId) {
+        return messageStorage.get(messageId);
+      },
+
+      async sendChallengeResponse() {
+        if (challengeError) {
+          throw challengeError;
+        }
+      },
+
+      setChallengeStatus(status) {
+        challengeStatus = status;
+      },
+    });
+    await handler.load();
+    await handler.onOnline();
+    return handler;
+  };
+
+  const isInStorage = (messageId: string) => {
+    return (storage.get('challenge:retry-message-ids') || []).some(
+      ({ messageId: storageId }: { messageId: string }) => {
+        return storageId === messageId;
+      }
+    );
+  };
+
+  it('should automatically retry after timeout', async () => {
+    const handler = await createHandler();
+
+    const one = createMessage('1');
+    messageStorage.set('1', one);
+
+    await handler.register(one);
+    assert.isTrue(isInStorage(one.id));
+    assert.equal(challengeStatus, 'required');
+
+    await sleep(50);
+
+    assert.deepEqual(sent, ['1']);
+    assert.equal(challengeStatus, 'idle');
+    assert.isFalse(isInStorage(one.id));
+  });
+
+  it('should send challenge response', async () => {
+    const handler = await createHandler({ challenge: true });
+
+    const one = createMessage('1', { retryAfter: Date.now() + 100000 });
+    messageStorage.set('1', one);
+
+    await handler.register(one);
+    assert.equal(challengeStatus, 'required');
+
+    await sleep(50);
+
+    assert.deepEqual(sent, ['1']);
+    assert.isFalse(isInStorage(one.id));
+    assert.equal(challengeStatus, 'idle');
+  });
+
+  it('should send old messages', async () => {
+    const handler = await createHandler();
+
+    const retryAfter = Date.now() + 50;
+
+    // Put messages in reverse order to validate that the send order is correct
+    const messages = [
+      createMessage('3', { sentAt: 3, retryAfter }),
+      createMessage('2', { sentAt: 2, retryAfter }),
+      createMessage('1', { sentAt: 1, retryAfter }),
+    ];
+    for (const message of messages) {
+      messageStorage.set(message.id, message);
+      await handler.register(message);
+    }
+
+    assert.equal(challengeStatus, 'required');
+    assert.deepEqual(sent, []);
+
+    assert.equal(challengeStatus, 'required');
+    for (const message of messages) {
+      assert.isTrue(
+        isInStorage(message.id),
+        `${message.id} should be in storage`
+      );
+    }
+
+    await handler.onOffline();
+
+    // Wait for messages to mature
+    await sleep(50);
+
+    // Create new handler to load old messages from storage
+    await createHandler();
+    for (const message of messages) {
+      await handler.unregister(message);
+    }
+
+    for (const message of messages) {
+      assert.isFalse(
+        isInStorage(message.id),
+        `${message.id} should not be in storage`
+      );
+    }
+
+    // The order has to be correct
+    assert.deepEqual(sent, ['1', '2', '3']);
+    assert.equal(challengeStatus, 'idle');
+  });
+
+  it('should send message immediately if it is ready', async () => {
+    const handler = await createHandler();
+
+    const one = createMessage('1', { retryAfter: Date.now() - 100 });
+    await handler.register(one);
+
+    assert.equal(challengeStatus, 'idle');
+    assert.deepEqual(sent, ['1']);
+  });
+
+  it('should not change challenge status on non-bubble messages', async () => {
+    const handler = await createHandler();
+
+    const one = createMessage('1', { isNormalBubble: false });
+    await handler.register(one);
+
+    assert.equal(challengeStatus, 'idle');
+    assert.deepEqual(sent, []);
+
+    await sleep(50);
+    assert.deepEqual(sent, ['1']);
+  });
+
+  it('should not retry expired messages', async () => {
+    const handler = await createHandler();
+
+    const bubble = createMessage('1');
+    messageStorage.set('1', bubble);
+    await handler.register(bubble);
+    assert.isTrue(isInStorage(bubble.id));
+
+    const newHandler = await createHandler({
+      challenge: true,
+      expireAfter: -1,
+    });
+    await handler.unregister(bubble);
+
+    challengeStatus = 'idle';
+    await newHandler.load();
+
+    assert.equal(challengeStatus, 'idle');
+    assert.deepEqual(sent, []);
+
+    await sleep(25);
+
+    assert.equal(challengeStatus, 'idle');
+    assert.deepEqual(sent, []);
+    assert.isFalse(isInStorage(bubble.id));
+  });
+
+  it('should send messages that matured while we were offline', async () => {
+    const handler = await createHandler();
+
+    const one = createMessage('1');
+    messageStorage.set('1', one);
+    await handler.register(one);
+
+    assert.isTrue(isInStorage(one.id));
+    assert.deepEqual(sent, []);
+    assert.equal(challengeStatus, 'required');
+
+    await handler.onOffline();
+
+    // Let messages mature
+    await sleep(50);
+
+    assert.isTrue(isInStorage(one.id));
+    assert.deepEqual(sent, []);
+    assert.equal(challengeStatus, 'required');
+
+    // Go back online
+    await handler.onOnline();
+
+    assert.isFalse(isInStorage(one.id));
+    assert.deepEqual(sent, [one.id]);
+    assert.equal(challengeStatus, 'idle');
+  });
+
+  it('should not retry more than 5 times', async () => {
+    const handler = await createHandler();
+
+    const one = createMessage('1', {
+      retryAfter: Date.now() + 50,
+    });
+    messageStorage.set('1', one);
+    await handler.register(one);
+
+    const retrySend = sinon.stub(one, 'retrySend');
+
+    assert.isTrue(isInStorage(one.id));
+    assert.deepEqual(sent, []);
+    assert.equal(challengeStatus, 'required');
+
+    // Let it spam the server
+    await sleep(100);
+
+    assert.isTrue(isInStorage(one.id));
+    assert.deepEqual(sent, []);
+    assert.equal(challengeStatus, 'required');
+
+    sinon.assert.callCount(retrySend, 5);
+  });
+
+  it('should trigger onChallengeSolved', async () => {
+    const onChallengeSolved = sinon.stub();
+
+    const handler = await createHandler({
+      challenge: true,
+      onChallengeSolved,
+    });
+
+    const one = createMessage('1', {
+      retryAfter: Date.now() + 1,
+    });
+    messageStorage.set('1', one);
+    await handler.register(one);
+
+    // Let the challenge go through
+    await sleep(50);
+
+    sinon.assert.calledOnce(onChallengeSolved);
+  });
+
+  it('should trigger onChallengeFailed', async () => {
+    const onChallengeFailed = sinon.stub();
+
+    const handler = await createHandler({
+      challenge: true,
+      challengeError: new Error('custom failure'),
+      onChallengeFailed,
+    });
+
+    const one = createMessage('1', {
+      retryAfter: Date.now() + 1,
+    });
+    messageStorage.set('1', one);
+    await handler.register(one);
+
+    // Let the challenge go through
+    await sleep(50);
+
+    sinon.assert.calledOnce(onChallengeFailed);
+  });
+});

ts/test-both/state/ducks/network_test.ts

@@ -0,0 +1,26 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { actions, getEmptyState, reducer } from '../../../state/ducks/network';
+
+describe('both/state/ducks/network', () => {
+  describe('setChallengeStatus', () => {
+    const { setChallengeStatus } = actions;
+
+    it('updates whether we need to complete a server challenge', () => {
+      const idleState = reducer(getEmptyState(), setChallengeStatus('idle'));
+      assert.equal(idleState.challengeStatus, 'idle');
+
+      const requiredState = reducer(idleState, setChallengeStatus('required'));
+      assert.equal(requiredState.challengeStatus, 'required');
+
+      const pendingState = reducer(
+        requiredState,
+        setChallengeStatus('pending')
+      );
+      assert.equal(pendingState.challengeStatus, 'pending');
+    });
+  });
+});

ts/test-both/util/parseRetryAfter_test.ts

@@ -0,0 +1,22 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { parseRetryAfter } from '../../util/parseRetryAfter';
+
+describe('parseRetryAfter', () => {
+  it('should return 0 on invalid input', () => {
+    assert.equal(parseRetryAfter('nope'), 1000);
+    assert.equal(parseRetryAfter('1ff'), 1000);
+  });
+
+  it('should return milleseconds on valid input', () => {
+    assert.equal(parseRetryAfter('100'), 100000);
+  });
+
+  it('should return apply minimum value', () => {
+    assert.equal(parseRetryAfter('0'), 1000);
+    assert.equal(parseRetryAfter('-1'), 1000);
+  });
+});

ts/test-node/util/sgnlHref_test.ts

@@ -7,8 +7,10 @@ import { LoggerType } from '../../types/Logging';
 
 import {
   isSgnlHref,
+  isCaptchaHref,
   isSignalHttpsLink,
   parseSgnlHref,
+  parseCaptchaHref,
   parseSignalHttpsLink,
 } from '../../util/sgnlHref';
 
@@ -26,65 +28,71 @@ const explodingLogger: LoggerType = {
 };
 
 describe('sgnlHref', () => {
-  describe('isSgnlHref', () => {
+  [
-    it('returns false for non-strings', () => {
+    { protocol: 'sgnl', check: isSgnlHref, name: 'isSgnlHref' },
-      const logger = {
+    { protocol: 'signalcaptcha', check: isCaptchaHref, name: 'isCaptchaHref' },
-        ...explodingLogger,
+  ].forEach(({ protocol, check, name }) => {
-        warn: Sinon.spy(),
+    describe(name, () => {
-      };
+      it('returns false for non-strings', () => {
+        const logger = {
+          ...explodingLogger,
+          warn: Sinon.spy(),
+        };
 
-      const castToString = (value: unknown): string => value as string;
+        const castToString = (value: unknown): string => value as string;
 
-      assert.isFalse(isSgnlHref(castToString(undefined), logger));
+        assert.isFalse(check(castToString(undefined), logger));
-      assert.isFalse(isSgnlHref(castToString(null), logger));
+        assert.isFalse(check(castToString(null), logger));
-      assert.isFalse(isSgnlHref(castToString(123), logger));
+        assert.isFalse(check(castToString(123), logger));
 
-      Sinon.assert.calledThrice(logger.warn);
+        Sinon.assert.calledThrice(logger.warn);
-    });
+      });
 
-    it('returns false for invalid URLs', () => {
+      it('returns false for invalid URLs', () => {
-      assert.isFalse(isSgnlHref('', explodingLogger));
+        assert.isFalse(check('', explodingLogger));
-      assert.isFalse(isSgnlHref('sgnl', explodingLogger));
+        assert.isFalse(check(protocol, explodingLogger));
-      assert.isFalse(isSgnlHref('sgnl://::', explodingLogger));
+        assert.isFalse(check(`${protocol}://::`, explodingLogger));
-    });
+      });
 
-    it('returns false if the protocol is not "sgnl:"', () => {
+      it(`returns false if the protocol is not "${protocol}:"`, () => {
-      assert.isFalse(isSgnlHref('https://example', explodingLogger));
+        assert.isFalse(check('https://example', explodingLogger));
-      assert.isFalse(
+        assert.isFalse(
-        isSgnlHref(
+          check('https://signal.art/addstickers/?pack_id=abc', explodingLogger)
-          'https://signal.art/addstickers/?pack_id=abc',
+        );
-          explodingLogger
+        assert.isFalse(check('signal://example', explodingLogger));
-        )
+      });
-      );
-      assert.isFalse(isSgnlHref('signal://example', explodingLogger));
-    });
 
-    it('returns true if the protocol is "sgnl:"', () => {
+      it(`returns true if the protocol is "${protocol}:"`, () => {
-      assert.isTrue(isSgnlHref('sgnl://', explodingLogger));
+        assert.isTrue(check(`${protocol}://`, explodingLogger));
-      assert.isTrue(isSgnlHref('sgnl://example', explodingLogger));
+        assert.isTrue(check(`${protocol}://example`, explodingLogger));
-      assert.isTrue(isSgnlHref('sgnl://example.com', explodingLogger));
+        assert.isTrue(check(`${protocol}://example.com`, explodingLogger));
-      assert.isTrue(isSgnlHref('SGNL://example', explodingLogger));
+        assert.isTrue(
-      assert.isTrue(isSgnlHref('sgnl://example?foo=bar', explodingLogger));
+          check(`${protocol.toUpperCase()}://example`, explodingLogger)
-      assert.isTrue(isSgnlHref('sgnl://example/', explodingLogger));
+        );
-      assert.isTrue(isSgnlHref('sgnl://example#', explodingLogger));
+        assert.isTrue(check(`${protocol}://example?foo=bar`, explodingLogger));
+        assert.isTrue(check(`${protocol}://example/`, explodingLogger));
+        assert.isTrue(check(`${protocol}://example#`, explodingLogger));
 
-      assert.isTrue(isSgnlHref('sgnl:foo', explodingLogger));
+        assert.isTrue(check(`${protocol}:foo`, explodingLogger));
 
-      assert.isTrue(isSgnlHref('sgnl://user:pass@example', explodingLogger));
+        assert.isTrue(
-      assert.isTrue(isSgnlHref('sgnl://example.com:1234', explodingLogger));
+          check(`${protocol}://user:pass@example`, explodingLogger)
-      assert.isTrue(
+        );
-        isSgnlHref('sgnl://example.com/extra/path/data', explodingLogger)
+        assert.isTrue(check(`${protocol}://example.com:1234`, explodingLogger));
-      );
+        assert.isTrue(
-      assert.isTrue(
+          check(`${protocol}://example.com/extra/path/data`, explodingLogger)
-        isSgnlHref('sgnl://example/?foo=bar#hash', explodingLogger)
+        );
-      );
+        assert.isTrue(
-    });
+          check(`${protocol}://example/?foo=bar#hash`, explodingLogger)
+        );
+      });
 
-    it('accepts URL objects', () => {
+      it('accepts URL objects', () => {
-      const invalid = new URL('https://example.com');
+        const invalid = new URL('https://example.com');
-      assert.isFalse(isSgnlHref(invalid, explodingLogger));
+        assert.isFalse(check(invalid, explodingLogger));
-      const valid = new URL('sgnl://example');
+        const valid = new URL(`${protocol}://example`);
-      assert.isTrue(isSgnlHref(valid, explodingLogger));
+        assert.isTrue(check(valid, explodingLogger));
+      });
     });
   });
 
@@ -255,6 +263,31 @@ describe('sgnlHref', () => {
     });
   });
 
+  describe('parseCaptchaHref', () => {
+    it('throws on invalid URLs', () => {
+      ['', 'sgnl', 'https://example/?foo=bar'].forEach(href => {
+        assert.throws(
+          () => parseCaptchaHref(href, explodingLogger),
+          'Not a captcha href'
+        );
+      });
+    });
+
+    it('parses the command for URLs with no arguments', () => {
+      [
+        'signalcaptcha://foo',
+        'signalcaptcha://foo?x=y',
+        'signalcaptcha://a:b@foo?x=y',
+        'signalcaptcha://foo#hash',
+        'signalcaptcha://foo/',
+      ].forEach(href => {
+        assert.deepEqual(parseCaptchaHref(href, explodingLogger), {
+          captcha: 'foo',
+        });
+      });
+    });
+  });
+
   describe('parseSignalHttpsLink', () => {
     it('returns a null command for invalid URLs', () => {
       ['', 'https', 'https://example/?foo=bar'].forEach(href => {

ts/textsecure/Errors.ts

@@ -4,6 +4,8 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable max-classes-per-file */
 
+import { parseRetryAfter } from '../util/parseRetryAfter';
+
 function appendStack(newError: Error, originalError: Error) {
   // eslint-disable-next-line no-param-reassign
   newError.stack += `\nOriginal stack:\n${originalError.stack}`;
@@ -104,6 +106,37 @@ export class SendMessageNetworkError extends ReplayableError {
   }
 }
 
+export type SendMessageChallengeData = {
+  readonly token?: string;
+  readonly options?: ReadonlyArray<string>;
+};
+
+export class SendMessageChallengeError extends ReplayableError {
+  public identifier: string;
+
+  public readonly data: SendMessageChallengeData | undefined;
+
+  public readonly retryAfter: number;
+
+  constructor(identifier: string, httpError: Error) {
+    super({
+      name: 'SendMessageChallengeError',
+      message: httpError.message,
+    });
+
+    [this.identifier] = identifier.split('.');
+    this.code = httpError.code;
+    this.data = httpError.response;
+
+    const headers = httpError.responseHeaders || {};
+
+    this.retryAfter =
+      Date.now() + parseRetryAfter(headers['retry-after'].toString());
+
+    appendStack(this, httpError);
+  }
+}
+
 export class SignedPreKeyRotationError extends ReplayableError {
   constructor() {
     super({

ts/textsecure/OutgoingMessage.ts

@@ -34,6 +34,7 @@ import {
   OutgoingIdentityKeyError,
   OutgoingMessageError,
   SendMessageNetworkError,
+  SendMessageChallengeError,
   UnregisteredUserError,
 } from './Errors';
 import { isValidNumber } from '../types/PhoneNumber';
@@ -163,12 +164,16 @@ export default class OutgoingMessage {
     let error = providedError;
 
     if (!error || (error.name === 'HTTPError' && error.code !== 404)) {
-      error = new OutgoingMessageError(
+      if (error && error.code === 428) {
-        identifier,
+        error = new SendMessageChallengeError(identifier, error);
-        this.message.toArrayBuffer(),
+      } else {
-        this.timestamp,
+        error = new OutgoingMessageError(
-        error
+          identifier,
-      );
+          this.message.toArrayBuffer(),
+          this.timestamp,
+          error
+        );
+      }
     }
 
     error.reason = reason;
@@ -370,10 +375,14 @@ export default class OutgoingMessage {
       if (e.name === 'HTTPError' && e.code !== 409 && e.code !== 410) {
         // 409 and 410 should bubble and be handled by doSendMessage
         // 404 should throw UnregisteredUserError
+        // 428 should throw SendMessageChallengeError
         // all other network errors can be retried later.
         if (e.code === 404) {
           throw new UnregisteredUserError(identifier, e);
         }
+        if (e.code === 428) {
+          throw new SendMessageChallengeError(identifier, e);
+        }
         throw new SendMessageNetworkError(identifier, jsonData, e);
       }
       throw e;

ts/textsecure/SendMessage.ts

@@ -16,6 +16,7 @@ import {
   GroupCredentialsType,
   GroupLogResponseType,
   ProxiedRequestOptionsType,
+  ChallengeType,
   WebAPIType,
 } from './WebAPI';
 import createTaskWithTimeout from './TaskWithTimeout';
@@ -1915,4 +1916,10 @@ export default class MessageSender {
   ): Promise<GroupExternalCredentialClass> {
     return this.server.getGroupExternalCredential(options);
   }
+
+  public async sendChallengeResponse(
+    challengeResponse: ChallengeType
+  ): Promise<void> {
+    return this.server.sendChallengeResponse(challengeResponse);
+  }
 }

ts/textsecure/WebAPI.ts

@@ -306,7 +306,8 @@ function getContentType(response: Response) {
   return null;
 }
 
-type HeaderListType = { [name: string]: string };
+type FetchHeaderListType = { [name: string]: string };
+type HeaderListType = { [name: string]: string | ReadonlyArray<string> };
 type HTTPCodeType = 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH';
 
 type RedactUrl = (url: string) => string;
@@ -397,7 +398,7 @@ async function _promiseAjax(
         'User-Agent': getUserAgent(options.version),
         'X-Signal-Agent': 'OWD',
         ...options.headers,
-      } as HeaderListType,
+      } as FetchHeaderListType,
       redirect: options.redirect,
       agent,
       ca: options.certificateAuthority,
@@ -500,6 +501,7 @@ async function _promiseAjax(
                     makeHTTPError(
                       'promiseAjax: invalid response',
                       response.status,
+                      response.headers.raw(),
                       result,
                       options.stack
                     )
@@ -563,6 +565,7 @@ async function _promiseAjax(
             makeHTTPError(
               'promiseAjax: error response',
               response.status,
+              response.headers.raw(),
               result,
               options.stack
             )
@@ -576,7 +579,7 @@ async function _promiseAjax(
           window.log.error(options.type, url, 0, 'Error');
         }
         const stack = `${e.stack}\nInitial stack:\n${options.stack}`;
-        reject(makeHTTPError('promiseAjax catch', 0, e.toString(), stack));
+        reject(makeHTTPError('promiseAjax catch', 0, {}, e.toString(), stack));
       });
   });
 }
@@ -614,6 +617,7 @@ declare global {
   interface Error {
     code?: number | string;
     response?: any;
+    responseHeaders?: HeaderListType;
     warn?: boolean;
   }
 }
@@ -621,6 +625,7 @@ declare global {
 function makeHTTPError(
   message: string,
   providedCode: number,
+  headers: HeaderListType,
   response: any,
   stack?: string
 ) {
@@ -628,6 +633,7 @@ function makeHTTPError(
   const e = new Error(`${message}; code: ${code}`);
   e.name = 'HTTPError';
   e.code = code;
+  e.responseHeaders = headers;
   if (DEBUG && response) {
     e.stack += `\nresponse: ${response}`;
   }
@@ -670,6 +676,7 @@ const URL_CALLS = {
   supportUnauthenticatedDelivery: 'v1/devices/unauthenticated_delivery',
   updateDeviceName: 'v1/accounts/name',
   whoami: 'v1/accounts/whoami',
+  challenge: 'v1/challenge',
 };
 
 type InitializeOptionsType = {
@@ -875,6 +882,7 @@ export type WebAPIType = {
     options: GroupCredentialsType
   ) => Promise<string>;
   whoami: () => Promise<any>;
+  sendChallengeResponse: (challengeResponse: ChallengeType) => Promise<any>;
   getConfig: () => Promise<
     Array<{ name: string; enabled: boolean; value: string | null }>
   >;
@@ -912,6 +920,12 @@ export type ServerKeysType = {
   identityKey: ArrayBuffer;
 };
 
+export type ChallengeType = {
+  readonly type: 'recaptcha';
+  readonly token: string;
+  readonly captcha: string;
+};
+
 export type ProxiedRequestOptionsType = {
   returnArrayBuffer?: boolean;
   start?: number;
@@ -1035,6 +1049,7 @@ export function initialize({
       updateDeviceName,
       uploadGroupAvatar,
       whoami,
+      sendChallengeResponse,
     };
 
     async function _ajax(param: AjaxOptionsType): Promise<any> {
@@ -1105,6 +1120,14 @@ export function initialize({
       });
     }
 
+    async function sendChallengeResponse(challengeResponse: ChallengeType) {
+      return _ajax({
+        call: 'challenge',
+        httpType: 'PUT',
+        jsonData: challengeResponse,
+      });
+    }
+
     async function getConfig() {
       type ResType = {
         config: Array<{ name: string; enabled: boolean; value: string | null }>;

ts/util/lint/exceptions.json

@@ -14140,6 +14140,41 @@
     "updated": "2021-01-06T00:47:54.313Z",
     "reasonDetail": "Needed to render remote video elements. Doesn't interact with the DOM."
   },
+  {
+    "rule": "jQuery-load(",
+    "path": "ts/challenge.js",
+    "line": "    async load() {",
+    "reasonCategory": "falseMatch",
+    "updated": "2021-05-05T23:11:22.692Z"
+  },
+  {
+    "rule": "jQuery-load(",
+    "path": "ts/challenge.js",
+    "line": "            // 1. `.load()` when the `window.storage` is ready",
+    "reasonCategory": "falseMatch",
+    "updated": "2021-05-05T23:11:22.692Z"
+  },
+  {
+    "rule": "jQuery-load(",
+    "path": "ts/challenge.ts",
+    "line": "// to the `ChallengeHandler` on `.load()` call (from `ts/background.ts`). They",
+    "reasonCategory": "falseMatch",
+    "updated": "2021-05-05T23:11:22.692Z"
+  },
+  {
+    "rule": "jQuery-load(",
+    "path": "ts/challenge.ts",
+    "line": "  public async load(): Promise<void> {",
+    "reasonCategory": "falseMatch",
+    "updated": "2021-05-05T23:11:22.692Z"
+  },
+  {
+    "rule": "jQuery-load(",
+    "path": "ts/challenge.ts",
+    "line": "        // 1. `.load()` when the `window.storage` is ready",
+    "reasonCategory": "falseMatch",
+    "updated": "2021-05-05T23:11:22.692Z"
+  },
   {
     "rule": "React-useRef",
     "path": "ts/components/AvatarInput.js",
@@ -14212,6 +14247,14 @@
     "updated": "2020-10-26T19:12:24.410Z",
     "reasonDetail": "Used to get the local video element for rendering."
   },
+  {
+    "rule": "React-useRef",
+    "path": "ts/components/CaptchaDialog.js",
+    "line": "    const buttonRef = react_1.useRef(null);",
+    "reasonCategory": "usageTrusted",
+    "updated": "2021-05-05T23:11:22.692Z",
+    "reasonDetail": "Used only to set focus"
+  },
   {
     "rule": "React-createRef",
     "path": "ts/components/CaptionEditor.js",

ts/util/parseRetryAfter.ts

@@ -0,0 +1,16 @@
+// Copyright 2021 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { isNormalNumber } from './isNormalNumber';
+
+const ONE_SECOND = 1000;
+const MINIMAL_RETRY_AFTER = ONE_SECOND;
+
+export function parseRetryAfter(value: string): number {
+  let retryAfter = parseInt(value, 10);
+  if (!isNormalNumber(retryAfter) || retryAfter.toString() !== value) {
+    retryAfter = 0;
+  }
+
+  return Math.max(retryAfter * ONE_SECOND, MINIMAL_RETRY_AFTER);
+}

ts/util/sgnlHref.ts

@@ -23,6 +23,14 @@ export function isSgnlHref(value: string | URL, logger: LoggerType): boolean {
   return url !== null && url.protocol === 'sgnl:';
 }
 
+export function isCaptchaHref(
+  value: string | URL,
+  logger: LoggerType
+): boolean {
+  const url = parseUrl(value, logger);
+  return url !== null && url.protocol === 'signalcaptcha:';
+}
+
 export function isSignalHttpsLink(
   value: string | URL,
   logger: LoggerType
@@ -64,6 +72,23 @@ export function parseSgnlHref(
   };
 }
 
+type ParsedCaptchaHref = {
+  readonly captcha: string;
+};
+export function parseCaptchaHref(
+  href: URL | string,
+  logger: LoggerType
+): ParsedCaptchaHref {
+  const url = parseUrl(href, logger);
+  if (!url || !isCaptchaHref(url, logger)) {
+    throw new Error('Not a captcha href');
+  }
+
+  return {
+    captcha: url.host,
+  };
+}
+
 export function parseSignalHttpsLink(
   href: string,
   logger: LoggerType

ts/views/conversation_view.ts

@@ -85,6 +85,18 @@ Whisper.BlockedGroupToast = Whisper.ToastView.extend({
   },
 });
 
+Whisper.CaptchaSolvedToast = Whisper.ToastView.extend({
+  render_attributes() {
+    return { toastMessage: window.i18n('verificationComplete') };
+  },
+});
+
+Whisper.CaptchaFailedToast = Whisper.ToastView.extend({
+  render_attributes() {
+    return { toastMessage: window.i18n('verificationFailed') };
+  },
+});
+
 Whisper.LeftGroupToast = Whisper.ToastView.extend({
   render_attributes() {
     return { toastMessage: window.i18n('youLeftTheGroup') };
@@ -237,6 +249,12 @@ Whisper.ReactionFailedToast = Whisper.ToastView.extend({
   },
 });
 
+Whisper.DeleteForEveryoneFailedToast = Whisper.ToastView.extend({
+  render_attributes() {
+    return { toastMessage: window.i18n('deleteForEveryoneFailed') };
+  },
+});
+
 Whisper.GroupLinkCopiedToast = Whisper.ToastView.extend({
   render_attributes() {
     return { toastMessage: window.i18n('GroupLinkManagement--clipboard') };
@@ -2788,7 +2806,16 @@ Whisper.ConversationView = Whisper.View.extend({
       message: window.i18n('deleteForEveryoneWarning'),
       okText: window.i18n('delete'),
       resolve: async () => {
-        await this.model.sendDeleteForEveryoneMessage(message.get('sent_at'));
+        try {
+          await this.model.sendDeleteForEveryoneMessage(message.get('sent_at'));
+        } catch (error) {
+          window.log.error(
+            'Error sending delete-for-everyone',
+            error,
+            messageId
+          );
+          this.showToast(Whisper.DeleteForEveryoneFailedToast);
+        }
         this.resetPanel();
       },
     });

ts/window.d.ts

@@ -18,6 +18,10 @@ import {
   MessageAttributesType,
 } from './model-types.d';
 import { ContactRecordIdentityState, TextSecureType } from './textsecure.d';
+import {
+  ChallengeHandler,
+  IPCRequest as IPCChallengeRequest,
+} from './challenge';
 import { WebAPIConnectType } from './textsecure/WebAPI';
 import { uploadDebugLogs } from './logging/debuglogs';
 import { CallingClass } from './services/calling';
@@ -216,6 +220,7 @@ declare global {
     showWindow: () => void;
     showSettings: () => void;
     shutdown: () => void;
+    sendChallengeRequest: (request: IPCChallengeRequest) => void;
     setAutoHideMenuBar: (value: WhatIsThis) => void;
     setBadgeCount: (count: number) => void;
     setMenuBarVisibility: (value: WhatIsThis) => void;
@@ -522,6 +527,7 @@ declare global {
         getInitialState: () => WhatIsThis;
         load: () => void;
       };
+      challengeHandler: ChallengeHandler;
     };
 
     ConversationController: ConversationController;
@@ -580,6 +586,7 @@ export type DCodeIOType = {
 };
 
 type MessageControllerType = {
+  getById: (id: string) => MessageModel | undefined;
   findBySender: (sender: string) => MessageModel | null;
   findBySentAt: (sentAt: number) => MessageModel | null;
   register: (id: string, model: MessageModel) => MessageModel;
@@ -739,6 +746,8 @@ export type WhisperType = {
   BlockedGroupToast: typeof window.Whisper.ToastView;
   BlockedToast: typeof window.Whisper.ToastView;
   CannotMixImageAndNonImageAttachmentsToast: typeof window.Whisper.ToastView;
+  CaptchaSolvedToast: typeof window.Whisper.ToastView;
+  CaptchaFailedToast: typeof window.Whisper.ToastView;
   DangerousFileTypeToast: typeof window.Whisper.ToastView;
   ExpiredToast: typeof window.Whisper.ToastView;
   FileSavedToast: typeof window.Whisper.ToastView;
@@ -753,6 +762,7 @@ export type WhisperType = {
   OriginalNotFoundToast: typeof window.Whisper.ToastView;
   PinnedConversationsFullToast: typeof window.Whisper.ToastView;
   ReactionFailedToast: typeof window.Whisper.ToastView;
+  DeleteForEveryoneFailedToast: typeof window.Whisper.ToastView;
   TapToViewExpiredIncomingToast: typeof window.Whisper.ToastView;
   TapToViewExpiredOutgoingToast: typeof window.Whisper.ToastView;
   TimerConflictToast: typeof window.Whisper.ToastView;