Simplify ContactsParser

ts/textsecure/ContactsParser.preload.ts

@@ -1,17 +1,15 @@
 // Copyright 2020 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-import { Transform } from 'node:stream';
-
 import { createLogger } from '../logging/log.std.js';
 import { SignalService as Proto } from '../protobuf/index.std.js';
-import protobuf from '../protobuf/wrap.std.js';
 import { DurationInSeconds } from '../util/durations/index.std.js';
+import { DelimitedStream } from '../util/DelimitedStream.node.js';
 import {
   getAbsoluteAttachmentPath,
   writeNewAttachmentData,
-  maybeDeleteAttachmentFile,
 } from '../util/migrations.preload.js';
+import { strictAssert } from '../util/assert.std.js';
 import type { ContactAvatarType } from '../types/Avatar.std.js';
 import type { AttachmentType } from '../types/Attachment.std.js';
 import type { AciString } from '../types/ServiceId.std.js';
@@ -26,8 +24,6 @@ import { stringToMIMEType } from '../types/MIME.std.js';
 
 const log = createLogger('ContactsParser');
 
-const { Reader } = protobuf;
-
 type OptionalFields = {
   avatar?: Avatar | null;
   expireTimer?: number | null;
@@ -61,6 +57,8 @@ export async function parseContactsV2(
   }
 
   const parseContactsTransform = new ParseContactsTransform();
+  const contacts = new Array<ContactDetailsWithAvatar>();
+  parseContactsTransform.on('data', contact => contacts.push(contact));
 
   await decryptAttachmentV2ToSink(
     {
@@ -74,7 +72,7 @@ export async function parseContactsV2(
     parseContactsTransform
   );
 
-  return parseContactsTransform.contacts;
+  return contacts;
 }
 
 // This transform pulls contacts and their avatars from a stream of bytes. This is tricky,
@@ -82,125 +80,26 @@ export async function parseContactsV2(
 //   So we are ready for decodeDelimited() to throw, and to keep activeContact around
 //   while we wait for more chunks to get to the expected avatar size.
 // Note: exported only for testing
-export class ParseContactsTransform extends Transform {
-  public contacts: Array<ContactDetailsWithAvatar> = [];
+export class ParseContactsTransform extends DelimitedStream {
+  protected override getTrailerSize(frame: Buffer): number {
+    const contact = Proto.ContactDetails.decode(frame);
+    return contact.avatar?.length ?? 0;
+  }
 
-  public activeContact: Proto.ContactDetails | undefined;
-  #unused: Uint8Array | undefined;
-
-  override async _transform(
-    chunk: Buffer | undefined,
-    _encoding: string,
-    done: (error?: Error) => void
+  protected override async pushFrame(
+    frame: Buffer,
+    avatarData: Buffer
   ): Promise<void> {
-    if (!chunk || chunk.byteLength === 0) {
-      done();
-      return;
-    }
+    const contact = Proto.ContactDetails.decode(frame);
 
-    try {
-      let data = chunk;
-      if (this.#unused) {
-        data = Buffer.concat([this.#unused, data]);
-        this.#unused = undefined;
-      }
-
-      const reader = Reader.create(data);
-      while (reader.pos < reader.len) {
-        const startPos = reader.pos;
-
-        if (!this.activeContact) {
-          try {
-            this.activeContact = Proto.ContactDetails.decodeDelimited(reader);
-          } catch (err) {
-            // We get a RangeError if there wasn't enough data to read the next record.
-            if (err instanceof RangeError) {
-              // Note: A failed decodeDelimited() does in fact update reader.pos, so we
-              //   must reset to startPos
-              this.#unused = data.subarray(startPos);
-              done();
-              return;
-            }
-
-            // Something deeper has gone wrong; the proto is malformed or something
-            done(err);
-            return;
-          }
-        }
-
-        // Something has really gone wrong if the above parsing didn't throw but gave
-        //   us nothing back. Let's end the parse.
-        if (!this.activeContact) {
-          done(new Error('ParseContactsTransform: No active contact!'));
-          return;
-        }
-
-        const attachmentSize = this.activeContact?.avatar?.length ?? 0;
-        if (attachmentSize === 0) {
-          // No avatar attachment for this contact
-          const prepared = prepareContact(this.activeContact);
-          if (prepared) {
-            this.contacts.push(prepared);
-          }
-          this.activeContact = undefined;
-
-          continue;
-        }
-
-        const spaceLeftAfterRead = reader.len - (reader.pos + attachmentSize);
-        if (spaceLeftAfterRead >= 0) {
-          // We've read enough data to read the entire attachment
-          const avatarData = reader.buf.subarray(
-            reader.pos,
-            reader.pos + attachmentSize
-          );
-          const hash = computeHash(avatarData);
-
-          const local =
-            // eslint-disable-next-line no-await-in-loop
-            await writeNewAttachmentData(avatarData);
-
-          const contentType = this.activeContact.avatar?.contentType;
-          const prepared = prepareContact(this.activeContact, {
-            ...this.activeContact.avatar,
-            ...local,
-            contentType: contentType
-              ? stringToMIMEType(contentType)
-              : undefined,
-            hash,
-          });
-          if (prepared) {
-            this.contacts.push(prepared);
-          } else {
-            // eslint-disable-next-line no-await-in-loop
-            await maybeDeleteAttachmentFile(local.path);
-          }
-          this.activeContact = undefined;
-
-          reader.skip(attachmentSize);
-        } else {
-          // We have an attachment, but we haven't read enough data yet. We need to
-          //   wait for another chunk.
-          this.#unused = data.subarray(reader.pos);
-          done();
-          return;
-        }
-      }
-
-      // No need to push; no downstream consumers!
-    } catch (error) {
-      done(error);
-      return;
-    }
-
-    done();
+    this.push(await prepareContact(contact, avatarData));
   }
 }
 
-function prepareContact(
+async function prepareContact(
   { aci: rawAci, aciBinary, ...proto }: Proto.ContactDetails,
-  avatar?: ContactAvatarType
-): ContactDetailsWithAvatar | undefined {
+  avatarData: Uint8Array
+): Promise<ContactDetailsWithAvatar | undefined> {
   const expireTimer =
     proto.expireTimer != null
       ? DurationInSeconds.fromSeconds(proto.expireTimer)
@@ -213,7 +112,24 @@ function prepareContact(
     return undefined;
   }
 
-  const result = {
+  let avatar: ContactAvatarType | undefined;
+  if (avatarData.byteLength > 0) {
+    strictAssert(proto.avatar != null, 'Expected avatar with avatar data');
+
+    const hash = computeHash(avatarData);
+
+    const local = await writeNewAttachmentData(avatarData);
+
+    const contentType = proto.avatar?.contentType;
+    avatar = {
+      ...proto.avatar,
+      ...local,
+      contentType: contentType ? stringToMIMEType(contentType) : undefined,
+      hash,
+    };
+  }
+
+  return {
     ...proto,
     expireTimer,
     expireTimerVersion: proto.expireTimerVersion ?? null,
@@ -221,6 +137,4 @@ function prepareContact(
     avatar,
     number: dropNull(proto.number),
   };
-
-  return result;
 }