decode-wa-message.ts

import { Boom } from '@hapi/boom'
import { proto } from '../../WAProto/index.js'
import type { WAMessage, WAMessageKey } from '../Types'
import type { SignalRepositoryWithLIDStore } from '../Types/Signal'
import {
	areJidsSameUser,
	type BinaryNode,
	isHostedLidUser,
	isHostedPnUser,
	isJidBroadcast,
	isJidGroup,
	isJidMetaAI,
	isJidNewsletter,
	isJidStatusBroadcast,
	isLidUser,
	isPnUser
	//	transferDevice
} from '../WABinary'
import { unpadRandomMax16 } from './generics'
import type { ILogger } from './logger'

export const getDecryptionJid = async (sender: string, repository: SignalRepositoryWithLIDStore): Promise<string> => {
	if (isLidUser(sender) || isHostedLidUser(sender)) {
		return sender
	}

	const mapped = await repository.lidMapping.getLIDForPN(sender)
	return mapped || sender
}

const storeMappingFromEnvelope = async (
	stanza: BinaryNode,
	sender: string,
	repository: SignalRepositoryWithLIDStore,
	decryptionJid: string,
	logger: ILogger
): Promise<void> => {
	// TODO: Handle hosted IDs
	const { senderAlt } = extractAddressingContext(stanza)

	if (senderAlt && isLidUser(senderAlt) && isPnUser(sender) && decryptionJid === sender) {
		try {
			await repository.lidMapping.storeLIDPNMappings([{ lid: senderAlt, pn: sender }])
			await repository.migrateSession(sender, senderAlt)
			logger.debug({ sender, senderAlt }, 'Stored LID mapping from envelope')
		} catch (error) {
			logger.warn({ sender, senderAlt, error }, 'Failed to store LID mapping')
		}
	}
}

export const NO_MESSAGE_FOUND_ERROR_TEXT = 'Message absent from node'
export const MISSING_KEYS_ERROR_TEXT = 'Key used already or never filled'

// Retry configuration for failed decryption
export const DECRYPTION_RETRY_CONFIG = {
	maxRetries: 3,
	baseDelayMs: 100,
	sessionRecordErrors: ['No session record', 'SessionError: No session record']
}

export const NACK_REASONS = {
	ParsingError: 487,
	UnrecognizedStanza: 488,
	UnrecognizedStanzaClass: 489,
	UnrecognizedStanzaType: 490,
	InvalidProtobuf: 491,
	InvalidHostedCompanionStanza: 493,
	MissingMessageSecret: 495,
	SignalErrorOldCounter: 496,
	MessageDeletedOnPeer: 499,
	UnhandledError: 500,
	UnsupportedAdminRevoke: 550,
	UnsupportedLIDGroup: 551,
	DBOperationFailed: 552
}

type MessageType =
	| 'chat'
	| 'peer_broadcast'
	| 'other_broadcast'
	| 'group'
	| 'direct_peer_status'
	| 'other_status'
	| 'newsletter'

export const extractAddressingContext = (stanza: BinaryNode) => {
	let senderAlt: string | undefined
	let recipientAlt: string | undefined

	const sender = stanza.attrs.participant || stanza.attrs.from
	const addressingMode = stanza.attrs.addressing_mode || (sender?.endsWith('lid') ? 'lid' : 'pn')

	if (addressingMode === 'lid') {
		// Message is LID-addressed: sender is LID, extract corresponding PN
		// without device data
		senderAlt = stanza.attrs.participant_pn || stanza.attrs.sender_pn || stanza.attrs.peer_recipient_pn
		recipientAlt = stanza.attrs.recipient_pn
		// with device data
		//if (sender && senderAlt) senderAlt = transferDevice(sender, senderAlt)
	} else {
		// Message is PN-addressed: sender is PN, extract corresponding LID
		// without device data
		senderAlt = stanza.attrs.participant_lid || stanza.attrs.sender_lid || stanza.attrs.peer_recipient_lid
		recipientAlt = stanza.attrs.recipient_lid

		//with device data
		//if (sender && senderAlt) senderAlt = transferDevice(sender, senderAlt)
	}

	return {
		addressingMode,
		senderAlt,
		recipientAlt
	}
}

/**
 * Decode the received node as a message.
 * @note this will only parse the message, not decrypt it
 */
export function decodeMessageNode(stanza: BinaryNode, meId: string, meLid: string) {
	let msgType: MessageType
	let chatId: string
	let author: string
	let fromMe = false

	const msgId = stanza.attrs.id
	const from = stanza.attrs.from
	const participant: string | undefined = stanza.attrs.participant
	const recipient: string | undefined = stanza.attrs.recipient

	const addressingContext = extractAddressingContext(stanza)

	const isMe = (jid: string) => areJidsSameUser(jid, meId)
	const isMeLid = (jid: string) => areJidsSameUser(jid, meLid)

	if (isPnUser(from) || isLidUser(from) || isHostedLidUser(from) || isHostedPnUser(from)) {
		if (recipient && !isJidMetaAI(recipient)) {
			if (!isMe(from!) && !isMeLid(from!)) {
				throw new Boom('receipient present, but msg not from me', { data: stanza })
			}

			if (isMe(from!) || isMeLid(from!)) {
				fromMe = true
			}

			chatId = recipient
		} else {
			chatId = from!
		}

		msgType = 'chat'
		author = from!
	} else if (isJidGroup(from)) {
		if (!participant) {
			throw new Boom('No participant in group message')
		}

		if (isMe(participant) || isMeLid(participant)) {
			fromMe = true
		}

		msgType = 'group'
		author = participant
		chatId = from!
	} else if (isJidBroadcast(from)) {
		if (!participant) {
			throw new Boom('No participant in group message')
		}

		const isParticipantMe = isMe(participant)
		if (isJidStatusBroadcast(from!)) {
			msgType = isParticipantMe ? 'direct_peer_status' : 'other_status'
		} else {
			msgType = isParticipantMe ? 'peer_broadcast' : 'other_broadcast'
		}

		fromMe = isParticipantMe
		chatId = from!
		author = participant
	} else if (isJidNewsletter(from)) {
		msgType = 'newsletter'
		chatId = from!
		author = from!

		if (isMe(from!) || isMeLid(from!)) {
			fromMe = true
		}
	} else {
		throw new Boom('Unknown message type', { data: stanza })
	}

	const pushname = stanza?.attrs?.notify

	const key: WAMessageKey = {
		remoteJid: chatId,
		remoteJidAlt: !isJidGroup(chatId) ? addressingContext.senderAlt : undefined,
		remoteJidUsername: !isJidGroup(chatId)
			? stanza.attrs.peer_recipient_username || stanza.attrs.recipient_username
			: undefined,
		fromMe,
		id: msgId,
		participant,
		participantAlt: isJidGroup(chatId) ? addressingContext.senderAlt : undefined,
		participantUsername: stanza.attrs.participant ? stanza.attrs.participant_username : undefined,
		addressingMode: addressingContext.addressingMode,
		...(msgType === 'newsletter' && stanza.attrs.server_id ? { server_id: stanza.attrs.server_id } : {})
	}

	const fullMessage: WAMessage = {
		key,
		category: stanza.attrs.category,
		messageTimestamp: +stanza.attrs.t!,
		pushName: pushname,
		broadcast: isJidBroadcast(from)
	}

	if (key.fromMe) {
		fullMessage.status = proto.WebMessageInfo.Status.SERVER_ACK
	}

	return {
		fullMessage,
		author,
		sender: msgType === 'chat' ? author : chatId
	}
}

export const decryptMessageNode = (
	stanza: BinaryNode,
	meId: string,
	meLid: string,
	repository: SignalRepositoryWithLIDStore,
	logger: ILogger
) => {
	const { fullMessage, author, sender } = decodeMessageNode(stanza, meId, meLid)
	return {
		fullMessage,
		category: stanza.attrs.category,
		author,
		async decrypt() {
			let decryptables = 0
			if (Array.isArray(stanza.content)) {
				for (const { tag, attrs, content } of stanza.content) {
					if (tag === 'verified_name' && content instanceof Uint8Array) {
						const cert = proto.VerifiedNameCertificate.decode(content)
						const details = proto.VerifiedNameCertificate.Details.decode(cert.details!)
						fullMessage.verifiedBizName = details.verifiedName
					}

					if (tag === 'unavailable' && attrs.type === 'view_once') {
						fullMessage.key.isViewOnce = true // TODO: remove from here and add a STUB TYPE
					}

					if (attrs.count && tag === 'enc') {
						fullMessage.retryCount = Number(attrs.count)
					}

					if (tag !== 'enc' && tag !== 'plaintext') {
						continue
					}

					if (!(content instanceof Uint8Array)) {
						continue
					}

					decryptables += 1

					let msgBuffer: Uint8Array

					const decryptionJid = await getDecryptionJid(author, repository)

					if (tag !== 'plaintext') {
						// TODO: Handle hosted devices
						await storeMappingFromEnvelope(stanza, author, repository, decryptionJid, logger)
					}

					try {
						const e2eType = tag === 'plaintext' ? 'plaintext' : attrs.type

						switch (e2eType) {
							case 'skmsg':
								msgBuffer = await repository.decryptGroupMessage({
									group: sender,
									authorJid: author,
									msg: content
								})
								break
							case 'pkmsg':
							case 'msg':
								msgBuffer = await repository.decryptMessage({
									jid: decryptionJid,
									type: e2eType,
									ciphertext: content
								})
								break
							case 'plaintext':
								msgBuffer = content
								break
							default:
								throw new Error(`Unknown e2e type: ${e2eType}`)
						}

						let msg: proto.IMessage = proto.Message.decode(
							e2eType !== 'plaintext' ? unpadRandomMax16(msgBuffer) : msgBuffer
						)
						msg = msg.deviceSentMessage?.message || msg
						if (msg.senderKeyDistributionMessage) {
							//eslint-disable-next-line max-depth
							try {
								await repository.processSenderKeyDistributionMessage({
									authorJid: author,
									item: msg.senderKeyDistributionMessage
								})
							} catch (err) {
								logger.error({ key: fullMessage.key, err }, 'failed to process sender key distribution message')
							}
						}

						if (fullMessage.message) {
							Object.assign(fullMessage.message, msg)
						} else {
							fullMessage.message = msg
						}
					} catch (err: any) {
						const errorContext = {
							key: fullMessage.key,
							err,
							messageType: tag === 'plaintext' ? 'plaintext' : attrs.type,
							sender,
							author,
							isSessionRecordError: isSessionRecordError(err)
						}

						logger.error(errorContext, 'failed to decrypt message')

						fullMessage.messageStubType = proto.WebMessageInfo.StubType.CIPHERTEXT
						fullMessage.messageStubParameters = [err.message.toString()]
					}
				}
			}

			// if nothing was found to decrypt
			if (!decryptables && !fullMessage.key?.isViewOnce) {
				fullMessage.messageStubType = proto.WebMessageInfo.StubType.CIPHERTEXT
				fullMessage.messageStubParameters = [NO_MESSAGE_FOUND_ERROR_TEXT]
			}
		}
	}
}

/**
 * Utility function to check if an error is related to missing session record
 */
function isSessionRecordError(error: any): boolean {
	const errorMessage = error?.message || error?.toString() || ''
	return DECRYPTION_RETRY_CONFIG.sessionRecordErrors.some(errorPattern => errorMessage.includes(errorPattern))
}