125 lines
6.9 KiB
Kotlin
125 lines
6.9 KiB
Kotlin
package org.session.libsession.messaging.sending_receiving
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import org.session.libsession.messaging.MessagingModuleConfiguration
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import org.session.libsession.messaging.messages.Message
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import org.session.libsession.messaging.messages.control.*
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import org.session.libsession.messaging.messages.visible.VisibleMessage
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import org.session.libsession.utilities.GroupUtil
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import org.session.libsignal.crypto.PushTransportDetails
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import org.session.libsignal.protos.SignalServiceProtos
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object MessageReceiver {
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internal sealed class Error(message: String) : Exception(message) {
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object DuplicateMessage: Error("Duplicate message.")
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object InvalidMessage: Error("Invalid message.")
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object UnknownMessage: Error("Unknown message type.")
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object UnknownEnvelopeType: Error("Unknown envelope type.")
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object DecryptionFailed : Exception("Couldn't decrypt message.")
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object InvalidSignature: Error("Invalid message signature.")
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object NoData: Error("Received an empty envelope.")
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object SenderBlocked: Error("Received a message from a blocked user.")
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object NoThread: Error("Couldn't find thread for message.")
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object SelfSend: Error("Message addressed at self.")
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object InvalidGroupPublicKey: Error("Invalid group public key.")
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object NoGroupKeyPair: Error("Missing group key pair.")
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internal val isRetryable: Boolean = when (this) {
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is DuplicateMessage, is InvalidMessage, is UnknownMessage,
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is UnknownEnvelopeType, is InvalidSignature, is NoData,
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is SenderBlocked, is SelfSend -> false
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else -> true
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}
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}
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internal fun parse(data: ByteArray, openGroupServerID: Long?, isRetry: Boolean = false): Pair<Message, SignalServiceProtos.Content> {
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val storage = MessagingModuleConfiguration.shared.storage
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val userPublicKey = storage.getUserPublicKey()
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val isOpenGroupMessage = (openGroupServerID != null)
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// Parse the envelope
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val envelope = SignalServiceProtos.Envelope.parseFrom(data)
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// If the message failed to process the first time around we retry it later (if the error is retryable). In this case the timestamp
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// will already be in the database but we don't want to treat the message as a duplicate. The isRetry flag is a simple workaround
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// for this issue.
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if (storage.isDuplicateMessage(envelope.timestamp, GroupUtil.doubleEncodeGroupID(envelope.source)) && !isRetry) {
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throw Error.DuplicateMessage
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}
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// Decrypt the contents
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val ciphertext = envelope.content ?: throw Error.NoData
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var plaintext: ByteArray? = null
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var sender: String? = null
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var groupPublicKey: String? = null
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if (isOpenGroupMessage) {
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plaintext = envelope.content.toByteArray()
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sender = envelope.source
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} else {
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when (envelope.type) {
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SignalServiceProtos.Envelope.Type.SESSION_MESSAGE -> {
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val userX25519KeyPair = MessagingModuleConfiguration.shared.storage.getUserX25519KeyPair()
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val decryptionResult = MessageDecrypter.decrypt(ciphertext.toByteArray(), userX25519KeyPair)
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plaintext = decryptionResult.first
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sender = decryptionResult.second
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}
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SignalServiceProtos.Envelope.Type.CLOSED_GROUP_MESSAGE -> {
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val hexEncodedGroupPublicKey = envelope.source
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if (hexEncodedGroupPublicKey == null || !MessagingModuleConfiguration.shared.storage.isClosedGroup(hexEncodedGroupPublicKey)) {
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throw Error.InvalidGroupPublicKey
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}
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val encryptionKeyPairs = MessagingModuleConfiguration.shared.storage.getClosedGroupEncryptionKeyPairs(hexEncodedGroupPublicKey)
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if (encryptionKeyPairs.isEmpty()) { throw Error.NoGroupKeyPair }
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// Loop through all known group key pairs in reverse order (i.e. try the latest key pair first (which'll more than
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// likely be the one we want) but try older ones in case that didn't work)
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var encryptionKeyPair = encryptionKeyPairs.removeLast()
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fun decrypt() {
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try {
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val decryptionResult = MessageDecrypter.decrypt(ciphertext.toByteArray(), encryptionKeyPair)
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plaintext = decryptionResult.first
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sender = decryptionResult.second
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} catch (e: Exception) {
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if (encryptionKeyPairs.isNotEmpty()) {
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encryptionKeyPair = encryptionKeyPairs.removeLast()
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decrypt()
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} else {
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throw e
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}
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}
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}
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groupPublicKey = envelope.source
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decrypt()
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}
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else -> throw Error.UnknownEnvelopeType
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}
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}
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// Don't process the envelope any further if the message has been handled already
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if (storage.isDuplicateMessage(envelope.timestamp, sender!!) && !isRetry) throw Error.DuplicateMessage
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// Don't process the envelope any further if the sender is blocked
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if (isBlocked(sender!!)) throw Error.SenderBlocked
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// Parse the proto
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val proto = SignalServiceProtos.Content.parseFrom(PushTransportDetails.getStrippedPaddingMessageBody(plaintext))
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// Parse the message
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val message: Message = ReadReceipt.fromProto(proto) ?:
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TypingIndicator.fromProto(proto) ?:
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ClosedGroupControlMessage.fromProto(proto) ?:
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DataExtractionNotification.fromProto(proto) ?:
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ExpirationTimerUpdate.fromProto(proto) ?:
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ConfigurationMessage.fromProto(proto) ?:
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VisibleMessage.fromProto(proto) ?: throw Error.UnknownMessage
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// Ignore self send if needed
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if (!message.isSelfSendValid && sender == userPublicKey) throw Error.SelfSend
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// Guard against control messages in open groups
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if (isOpenGroupMessage && message !is VisibleMessage) throw Error.InvalidMessage
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// Finish parsing
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message.sender = sender
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message.recipient = userPublicKey
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message.sentTimestamp = envelope.timestamp
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message.receivedTimestamp = if (envelope.hasServerTimestamp()) envelope.serverTimestamp else System.currentTimeMillis()
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message.groupPublicKey = groupPublicKey
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message.openGroupServerMessageID = openGroupServerID
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// Validate
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var isValid = message.isValid()
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if (message is VisibleMessage && !isValid && proto.dataMessage.attachmentsCount != 0) { isValid = true }
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if (!isValid) { throw Error.InvalidMessage }
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// Return
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return Pair(message, proto)
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}
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} |