tunnelkit/Sources/CTunnelKitOpenVPNProtocol/ControlPacket.m

226 lines
7.5 KiB
Objective-C

//
// ControlPacket.m
// TunnelKit
//
// Created by Davide De Rosa on 9/14/18.
// Copyright (c) 2024 Davide De Rosa. All rights reserved.
//
// https://github.com/passepartoutvpn
//
// This file is part of TunnelKit.
//
// TunnelKit is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// TunnelKit is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with TunnelKit. If not, see <http://www.gnu.org/licenses/>.
//
#import "ControlPacket.h"
#import "Crypto.h"
@implementation ControlPacket
- (instancetype)initWithCode:(PacketCode)code
key:(uint8_t)key
sessionId:(NSData *)sessionId
packetId:(uint32_t)packetId
payload:(nullable NSData *)payload
{
NSCParameterAssert(sessionId.length == PacketSessionIdLength);
if (!(self = [super init])) {
return nil;
}
_code = code;
_key = key;
_sessionId = sessionId;
_packetId = packetId;
_payload = payload;
self.sentDate = nil;
return self;
}
- (instancetype)initWithKey:(uint8_t)key
sessionId:(NSData *)sessionId
ackIds:(NSArray<NSNumber *> *)ackIds
ackRemoteSessionId:(NSData *)ackRemoteSessionId
{
NSCParameterAssert(sessionId.length == PacketSessionIdLength);
NSCParameterAssert(ackRemoteSessionId.length == PacketSessionIdLength);
if (!(self = [super init])) {
return nil;
}
_packetId = UINT32_MAX; // bogus marker
_code = PacketCodeAckV1;
_key = key;
_sessionId = sessionId;
_ackIds = ackIds;
_ackRemoteSessionId = ackRemoteSessionId;
self.sentDate = nil;
return self;
}
- (BOOL)isAck
{
return (self.packetId == UINT32_MAX);
}
- (NSInteger)rawCapacity
{
const BOOL isAck = self.isAck;
const NSUInteger ackLength = self.ackIds.count;
NSCAssert(!isAck || ackLength > 0, @"Ack packet must provide positive ackLength");
NSInteger n = PacketAckLengthLength;
if (ackLength > 0) {
n += ackLength * PacketIdLength + PacketSessionIdLength;
}
if (!isAck) {
n += PacketIdLength;
}
n += self.payload.length;
return n;
}
// Ruby: send_ctrl
- (NSInteger)rawSerializeTo:(uint8_t *)to
{
uint8_t *ptr = to;
if (self.ackIds.count > 0) {
NSCParameterAssert(self.ackRemoteSessionId.length == PacketSessionIdLength);
*ptr = self.ackIds.count;
ptr += PacketAckLengthLength;
for (NSNumber *n in self.ackIds) {
const uint32_t ackId = (uint32_t)n.unsignedIntegerValue;
*(uint32_t *)ptr = CFSwapInt32HostToBig(ackId);
ptr += PacketIdLength;
}
memcpy(ptr, self.ackRemoteSessionId.bytes, PacketSessionIdLength);
ptr += PacketSessionIdLength;
}
else {
*ptr = 0; // no acks
ptr += PacketAckLengthLength;
}
if (self.code != PacketCodeAckV1) {
*(uint32_t *)ptr = CFSwapInt32HostToBig(self.packetId);
ptr += PacketIdLength;
if (self.payload) {
memcpy(ptr, self.payload.bytes, self.payload.length);
ptr += self.payload.length;
}
}
return ptr - to;
}
- (NSInteger)capacity
{
return PacketOpcodeLength + PacketSessionIdLength + self.rawCapacity;
}
- (NSData *)serialized
{
NSMutableData *data = [[NSMutableData alloc] initWithLength:self.capacity];
uint8_t *ptr = data.mutableBytes;
ptr += PacketHeaderSet(ptr, self.code, self.key, self.sessionId.bytes);
[self rawSerializeTo:ptr];
return data;
}
@end
@implementation ControlPacket (Authentication)
- (NSInteger)capacityWithAuthenticator:(id<Encrypter>)auth
{
return auth.digestLength + PacketReplayIdLength + PacketReplayTimestampLength + self.capacity;
}
- (BOOL)serializeTo:(uint8_t *)to authenticatingWith:(id<Encrypter>)auth replayId:(uint32_t)replayId timestamp:(uint32_t)timestamp error:(NSError *__autoreleasing _Nullable *)error
{
uint8_t *ptr = to + auth.digestLength;
const uint8_t *subject = ptr;
*(uint32_t *)ptr = CFSwapInt32HostToBig(replayId);
ptr += PacketReplayIdLength;
*(uint32_t *)ptr = CFSwapInt32HostToBig(timestamp);
ptr += PacketReplayTimestampLength;
ptr += PacketHeaderSet(ptr, self.code, self.key, self.sessionId.bytes);
ptr += [self rawSerializeTo:ptr];
const NSInteger subjectLength = ptr - subject;
NSInteger totalLength;
if (![auth encryptBytes:subject length:subjectLength dest:to destLength:&totalLength flags:NULL error:error]) {
return NO;
}
NSCAssert(totalLength == auth.digestLength + subjectLength, @"Encrypted packet size != (Digest + Subject)");
PacketSwap(to, auth.digestLength + PacketReplayIdLength + PacketReplayTimestampLength, PacketOpcodeLength + PacketSessionIdLength);
return YES;
}
- (NSData *)serializedWithAuthenticator:(id<Encrypter>)auth replayId:(uint32_t)replayId timestamp:(uint32_t)timestamp error:(NSError *__autoreleasing _Nullable *)error
{
NSMutableData *data = [[NSMutableData alloc] initWithLength:[self capacityWithAuthenticator:auth]];
if (![self serializeTo:data.mutableBytes authenticatingWith:auth replayId:replayId timestamp:timestamp error:error]) {
return nil;
}
return data;
}
@end
@implementation ControlPacket (Encryption)
- (NSInteger)capacityWithEncrypter:(id<Encrypter>)encrypter
{
return PacketOpcodeLength + PacketSessionIdLength + PacketReplayIdLength + PacketReplayTimestampLength + [encrypter encryptionCapacityWithLength:self.capacity];
}
- (BOOL)serializeTo:(uint8_t *)to encryptingWith:(nonnull id<Encrypter>)encrypter replayId:(uint32_t)replayId timestamp:(uint32_t)timestamp length:(NSInteger *)length adLength:(NSInteger)adLength error:(NSError *__autoreleasing _Nullable * _Nullable)error
{
uint8_t *ptr = to;
ptr += PacketHeaderSet(to, self.code, self.key, self.sessionId.bytes);
*(uint32_t *)ptr = CFSwapInt32HostToBig(replayId);
ptr += PacketReplayIdLength;
*(uint32_t *)ptr = CFSwapInt32HostToBig(timestamp);
ptr += PacketReplayTimestampLength;
NSAssert2(ptr - to == adLength, @"Incorrect AD bytes (%ld != %ld)", ptr - to, (long)adLength);
NSMutableData *msg = [[NSMutableData alloc] initWithLength:self.rawCapacity];
[self rawSerializeTo:msg.mutableBytes];
CryptoFlags flags;
flags.ad = to;
flags.adLength = adLength;
NSInteger encryptedMsgLength;
if (![encrypter encryptBytes:msg.bytes length:msg.length dest:(to + adLength) destLength:&encryptedMsgLength flags:&flags error:error]) {
return NO;
}
*length = adLength + encryptedMsgLength;
return YES;
}
- (NSData *)serializedWithEncrypter:(id<Encrypter>)encrypter replayId:(uint32_t)replayId timestamp:(uint32_t)timestamp adLength:(NSInteger)adLength error:(NSError *__autoreleasing _Nullable * _Nullable)error
{
NSMutableData *data = [[NSMutableData alloc] initWithLength:[self capacityWithEncrypter:encrypter]];
NSInteger length;
if (![self serializeTo:data.mutableBytes encryptingWith:encrypter replayId:replayId timestamp:timestamp length:&length adLength:adLength error:error]) {
return nil;
}
data.length = length;
return data;
}
@end