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//
// Copyright 2023 Signal Messenger, LLC.
// SPDX-License-Identifier: AGPL-3.0-only
//
package org.signal.libsignal.protocol;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.stream.IntStream;
import java.util.stream.Stream;
import org.signal.libsignal.internal.Native;
import org.signal.libsignal.protocol.util.Pair;
/**
* A parsed Sealed Sender v2 "SentMessage", ready to be fanned out to multiple recipients.
*
* The implementation assumes that every device for a particular recipient should use the same
* key material.
*/
public class SealedSenderMultiRecipientMessage {
private final byte[] fullMessageData;
private final Map recipients;
private final List excludedRecipients;
private final int offsetOfSharedData;
/**
* Per-recipient data for an SSv2 SentMessage.
*
* @see #messageForRecipient
*/
public static class Recipient {
private final byte[] devices;
private final short[] registrationIds;
private final int offsetOfRecipientSpecificKeyMaterial;
// This is redundant in the current SSv2 format, but if we didn't have it, we'd be hardcoding
// the length of the recipient-specific key material on the Java side.
private final int lengthOfRecipientSpecificKeyMaterial;
private Recipient(
byte[] devices,
short[] registrationIds,
int offsetOfRecipientSpecificKeyMaterial,
int lengthOfRecipientSpecificKeyMaterial) {
assert devices.length == registrationIds.length;
this.devices = devices;
this.registrationIds = registrationIds;
this.offsetOfRecipientSpecificKeyMaterial = offsetOfRecipientSpecificKeyMaterial;
this.lengthOfRecipientSpecificKeyMaterial = lengthOfRecipientSpecificKeyMaterial;
}
/**
* Returns the devices specified for this recipient.
*
* A valid message should never have duplicate devices, but the parsing does not enforce
* this.
*
*
The result is returned by reference; mutate it at your own detriment.
*/
public byte[] getDevices() {
return devices;
}
/**
* Returns a stream of (device ID, registration ID) pairs.
*
* @see #getDevices
*/
public Stream> getDevicesAndRegistrationIds() {
return IntStream.range(0, devices.length)
.mapToObj(i -> new Pair<>(devices[i], registrationIds[i]));
}
@Override
public boolean equals(Object other) {
if (!(other instanceof Recipient)) {
return false;
}
Recipient otherRecipient = (Recipient) other;
return Arrays.equals(devices, otherRecipient.devices)
&& Arrays.equals(registrationIds, otherRecipient.registrationIds)
&& offsetOfRecipientSpecificKeyMaterial
== otherRecipient.offsetOfRecipientSpecificKeyMaterial
&& lengthOfRecipientSpecificKeyMaterial
== otherRecipient.lengthOfRecipientSpecificKeyMaterial;
}
@Override
public int hashCode() {
// Leave out the length field, since in practice it will always be the same.
return offsetOfRecipientSpecificKeyMaterial
^ Arrays.hashCode(devices)
^ Arrays.hashCode(registrationIds);
}
}
/**
* Parses the input as an SSv2 SentMessage.
*
* The input is kept alive as long as the result is; it's used to implement {@link
* #messageForRecipient} and {@link #serialized}.
*
* @throws InvalidVersionException if the major version of the sealed sender message is
* unrecognized
* @throws InvalidMessageException if the message is malformed
*/
public static SealedSenderMultiRecipientMessage parse(byte[] input)
throws InvalidMessageException, InvalidVersionException {
return (SealedSenderMultiRecipientMessage)
Native.SealedSender_MultiRecipientParseSentMessage(input);
}
private SealedSenderMultiRecipientMessage(
byte[] fullMessageData,
Map recipients,
List excludedRecipients,
int offsetOfSharedData) {
this.fullMessageData = fullMessageData;
this.recipients = recipients;
this.excludedRecipients = excludedRecipients;
this.offsetOfSharedData = offsetOfSharedData;
}
/**
* Returns the serialized full message data.
*
* The result is returned by reference; mutate it at your own detriment.
*/
public byte[] serialized() {
return fullMessageData;
}
/**
* Returns the recipients parsed from the message.
*
*
The iteration order of the resulting Map is deterministic: the same input message data will
* produce the same output even across multiple runs.
*
*
The result is returned by reference; mutate it at your own detriment.
*/
public Map getRecipients() {
return recipients;
}
/**
* Returns the recipients excluded from receiving the message.
*
* This is enforced to be disjoint from the recipients in {@link #getRecipients}; it may be
* used for authorization purposes or just to check that certain recipients were deliberately
* excluded rather than accidentally.
*
*
The iteration order is deterministic: the same input message data will produce the same
* output even across multiple runs.
*
*
The result is returned by reference; mutate it at your own detriment.
*/
public List getExcludedRecipients() {
return excludedRecipients;
}
/**
* Returns the Sealed Sender V2 "ReceivedMessage" payload for delivery to a particular recipient.
*
* The same payload should be sent to all of the recipient's devices.
*/
public byte[] messageForRecipient(Recipient recipient) {
final int lengthOfSharedData = fullMessageData.length - offsetOfSharedData;
final ByteBuffer bbuf = ByteBuffer.allocate(messageSizeForRecipient(recipient));
bbuf.put((byte) 0x22); // The "original" Sealed Sender V2 version
bbuf.put(
fullMessageData,
recipient.offsetOfRecipientSpecificKeyMaterial,
recipient.lengthOfRecipientSpecificKeyMaterial);
bbuf.put(fullMessageData, offsetOfSharedData, lengthOfSharedData);
return bbuf.array();
}
/**
* Returns the length of the Sealed Sender V2 "ReceivedMessage" payload for delivery to a
* particular recipient, without copying any buffers.
*/
public int messageSizeForRecipient(Recipient recipient) {
final int lengthOfSharedData = fullMessageData.length - offsetOfSharedData;
return 1 /* version signature */
+ recipient.lengthOfRecipientSpecificKeyMaterial
+ lengthOfSharedData;
}
private static final byte SERIALIZED_RECIPIENT_VIEW_VERSION = 0x01;
private static final byte[] ZERO_DEVICE_IDS = new byte[0];
private static final short[] ZERO_REGISTRATION_IDS = new short[0];
/**
* Returns a serialized view for a particular {@link Recipient}.
*
*
This may be used to optimize temporary storage for future delivery—a single copy of
* the serialized message may be stored, and the full recipient list will not need to be reparsed
* to deliver to a single recipient.
*
* @see #serialized()
* @see #messageForRecipient(byte[], byte[])
*/
public byte[] serializedRecipientView(Recipient recipient) {
final ByteBuffer bbuf = ByteBuffer.allocate(1 + 4 + 4 + 4);
bbuf.put(SERIALIZED_RECIPIENT_VIEW_VERSION);
bbuf.putInt(offsetOfSharedData);
bbuf.putInt(recipient.offsetOfRecipientSpecificKeyMaterial);
bbuf.putInt(recipient.lengthOfRecipientSpecificKeyMaterial);
assert !bbuf.hasRemaining();
return bbuf.array();
}
/**
* Returns the Sealed Sender V2 "ReceivedMessage" payload for delivery to a particular recipient
* from its serialized view.
*
*
The same payload should be sent to all the recipient's devices.
*
* @see #serializedRecipientView(Recipient)
*/
public static byte[] messageForRecipient(byte[] fullMessageData, byte[] serializedRecipientView)
throws InvalidVersionException {
if (serializedRecipientView.length != 13) {
throw new IllegalArgumentException(
"Invalid length for serialized view: " + serializedRecipientView.length);
}
final ByteBuffer wrapped = ByteBuffer.wrap(serializedRecipientView);
final byte version = wrapped.get();
if (version != SERIALIZED_RECIPIENT_VIEW_VERSION) {
throw new InvalidVersionException("Recipient view version " + version + " is not supported");
}
final int offsetOfSharedData = wrapped.getInt();
final int offsetOfRecipientSpecificKeyMaterial = wrapped.getInt();
final int lengthOfRecipientSpecificKeyMaterial = wrapped.getInt();
assert !wrapped.hasRemaining();
// Device, registration, and excluded service IDs aren't used or checked in this path, so we can
// use empty arrays.
final Recipient recipient =
new Recipient(
ZERO_DEVICE_IDS,
ZERO_REGISTRATION_IDS,
offsetOfRecipientSpecificKeyMaterial,
lengthOfRecipientSpecificKeyMaterial);
final SealedSenderMultiRecipientMessage message =
new SealedSenderMultiRecipientMessage(
fullMessageData, Collections.emptyMap(), Collections.emptyList(), offsetOfSharedData);
return message.messageForRecipient(recipient);
}
}