293 lines
11 KiB
Swift
293 lines
11 KiB
Swift
//
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// ControlChannelSerializer.swift
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// TunnelKit
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//
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// Created by Davide De Rosa on 9/10/18.
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// Copyright (c) 2020 Davide De Rosa. All rights reserved.
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//
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// https://github.com/passepartoutvpn
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//
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// This file is part of TunnelKit.
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//
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// TunnelKit is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// TunnelKit is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with TunnelKit. If not, see <http://www.gnu.org/licenses/>.
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//
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import Foundation
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import SwiftyBeaver
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import __TunnelKitCore
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import __TunnelKitOpenVPN
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private let log = SwiftyBeaver.self
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protocol ControlChannelSerializer {
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func reset()
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func serialize(packet: ControlPacket) throws -> Data
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func deserialize(data: Data, start: Int, end: Int?) throws -> ControlPacket
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}
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extension OpenVPN.ControlChannel {
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class PlainSerializer: ControlChannelSerializer {
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func reset() {
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}
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func serialize(packet: ControlPacket) throws -> Data {
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return packet.serialized()
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}
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func deserialize(data packet: Data, start: Int, end: Int?) throws -> ControlPacket {
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var offset = start
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let end = end ?? packet.count
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guard end >= offset + PacketOpcodeLength else {
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throw OpenVPN.ControlChannelError("Missing opcode")
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}
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let codeValue = packet[offset] >> 3
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guard let code = PacketCode(rawValue: codeValue) else {
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throw OpenVPN.ControlChannelError("Unknown code: \(codeValue))")
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}
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let key = packet[offset] & 0b111
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offset += PacketOpcodeLength
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log.debug("Control: Try read packet with code \(code) and key \(key)")
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guard end >= offset + PacketSessionIdLength else {
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throw OpenVPN.ControlChannelError("Missing sessionId")
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}
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let sessionId = packet.subdata(offset: offset, count: PacketSessionIdLength)
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offset += PacketSessionIdLength
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guard end >= offset + 1 else {
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throw OpenVPN.ControlChannelError("Missing ackSize")
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}
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let ackSize = packet[offset]
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offset += 1
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var ackIds: [UInt32]?
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var ackRemoteSessionId: Data?
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if ackSize > 0 {
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guard end >= (offset + Int(ackSize) * PacketIdLength) else {
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throw OpenVPN.ControlChannelError("Missing acks")
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}
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var ids: [UInt32] = []
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for _ in 0..<ackSize {
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let id = packet.networkUInt32Value(from: offset)
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ids.append(id)
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offset += PacketIdLength
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}
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guard end >= offset + PacketSessionIdLength else {
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throw OpenVPN.ControlChannelError("Missing remoteSessionId")
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}
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let remoteSessionId = packet.subdata(offset: offset, count: PacketSessionIdLength)
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offset += PacketSessionIdLength
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ackIds = ids
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ackRemoteSessionId = remoteSessionId
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}
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if code == .ackV1 {
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guard let ackIds = ackIds else {
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throw OpenVPN.ControlChannelError("Ack packet without ids")
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}
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guard let ackRemoteSessionId = ackRemoteSessionId else {
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throw OpenVPN.ControlChannelError("Ack packet without remoteSessionId")
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}
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return ControlPacket(key: key, sessionId: sessionId, ackIds: ackIds as [NSNumber], ackRemoteSessionId: ackRemoteSessionId)
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}
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guard end >= offset + PacketIdLength else {
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throw OpenVPN.ControlChannelError("Missing packetId")
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}
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let packetId = packet.networkUInt32Value(from: offset)
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offset += PacketIdLength
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var payload: Data?
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if offset < end {
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payload = packet.subdata(in: offset..<end)
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}
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let controlPacket = ControlPacket(code: code, key: key, sessionId: sessionId, packetId: packetId, payload: payload)
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if let ackIds = ackIds {
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controlPacket.ackIds = ackIds as [NSNumber]
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controlPacket.ackRemoteSessionId = ackRemoteSessionId
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}
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return controlPacket
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}
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}
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}
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extension OpenVPN.ControlChannel {
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class AuthSerializer: ControlChannelSerializer {
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private let encrypter: Encrypter
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private let decrypter: Decrypter
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private let prefixLength: Int
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private let hmacLength: Int
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private let authLength: Int
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private let preambleLength: Int
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private var currentReplayId: BidirectionalState<UInt32>
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private let timestamp: UInt32
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private let plain: PlainSerializer
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init(withKey key: OpenVPN.StaticKey, digest: OpenVPN.Digest) throws {
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let crypto = CryptoBox(cipherAlgorithm: nil, digestAlgorithm: digest.rawValue)
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try crypto.configure(
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withCipherEncKey: nil,
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cipherDecKey: nil,
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hmacEncKey: key.hmacSendKey,
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hmacDecKey: key.hmacReceiveKey
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)
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encrypter = crypto.encrypter()
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decrypter = crypto.decrypter()
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prefixLength = PacketOpcodeLength + PacketSessionIdLength
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hmacLength = crypto.digestLength()
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authLength = hmacLength + PacketReplayIdLength + PacketReplayTimestampLength
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preambleLength = prefixLength + authLength
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currentReplayId = BidirectionalState(withResetValue: 1)
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timestamp = UInt32(Date().timeIntervalSince1970)
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plain = PlainSerializer()
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}
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func reset() {
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currentReplayId.reset()
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}
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func serialize(packet: ControlPacket) throws -> Data {
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return try serialize(packet: packet, timestamp: timestamp)
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}
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func serialize(packet: ControlPacket, timestamp: UInt32) throws -> Data {
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let data = try packet.serialized(withAuthenticator: encrypter, replayId: currentReplayId.outbound, timestamp: timestamp)
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currentReplayId.outbound += 1
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return data
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}
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// XXX: start/end are ignored, parses whole packet
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func deserialize(data packet: Data, start: Int, end: Int?) throws -> ControlPacket {
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let end = packet.count
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// data starts with (prefix=(header + sessionId) + auth=(hmac + replayId))
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guard end >= preambleLength else {
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throw OpenVPN.ControlChannelError("Missing HMAC")
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}
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// needs a copy for swapping
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var authPacket = packet
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let authCount = authPacket.count
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try authPacket.withUnsafeMutableBytes {
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let ptr = $0.bytePointer
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PacketSwapCopy(ptr, packet, prefixLength, authLength)
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try decrypter.verifyBytes(ptr, length: authCount, flags: nil)
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}
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// TODO: validate replay packet id
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return try plain.deserialize(data: authPacket, start: authLength, end: nil)
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}
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}
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}
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extension OpenVPN.ControlChannel {
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class CryptSerializer: ControlChannelSerializer {
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private let encrypter: Encrypter
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private let decrypter: Decrypter
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private let headerLength: Int
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private var adLength: Int
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private let tagLength: Int
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private var currentReplayId: BidirectionalState<UInt32>
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private let timestamp: UInt32
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private let plain: PlainSerializer
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init(withKey key: OpenVPN.StaticKey) throws {
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let crypto = CryptoBox(cipherAlgorithm: "AES-256-CTR", digestAlgorithm: "SHA256")
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try crypto.configure(
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withCipherEncKey: key.cipherEncryptKey,
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cipherDecKey: key.cipherDecryptKey,
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hmacEncKey: key.hmacSendKey,
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hmacDecKey: key.hmacReceiveKey
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)
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encrypter = crypto.encrypter()
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decrypter = crypto.decrypter()
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headerLength = PacketOpcodeLength + PacketSessionIdLength
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adLength = headerLength + PacketReplayIdLength + PacketReplayTimestampLength
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tagLength = crypto.tagLength()
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currentReplayId = BidirectionalState(withResetValue: 1)
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timestamp = UInt32(Date().timeIntervalSince1970)
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plain = PlainSerializer()
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}
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func reset() {
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currentReplayId.reset()
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}
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func serialize(packet: ControlPacket) throws -> Data {
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return try serialize(packet: packet, timestamp: timestamp)
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}
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func serialize(packet: ControlPacket, timestamp: UInt32) throws -> Data {
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let data = try packet.serialized(with: encrypter, replayId: currentReplayId.outbound, timestamp: timestamp, adLength: adLength)
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currentReplayId.outbound += 1
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return data
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}
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// XXX: start/end are ignored, parses whole packet
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func deserialize(data packet: Data, start: Int, end: Int?) throws -> ControlPacket {
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let end = end ?? packet.count
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// data starts with (ad=(header + sessionId + replayId) + tag)
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guard end >= start + adLength + tagLength else {
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throw OpenVPN.ControlChannelError("Missing AD+TAG")
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}
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let encryptedCount = packet.count - adLength
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var decryptedPacket = Data(count: decrypter.encryptionCapacity(withLength: encryptedCount))
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var decryptedCount = 0
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try packet.withUnsafeBytes {
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let src = $0.bytePointer
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var flags = CryptoFlags(iv: nil, ivLength: 0, ad: src, adLength: adLength)
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try decryptedPacket.withUnsafeMutableBytes {
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let dest = $0.bytePointer
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try decrypter.decryptBytes(src + flags.adLength, length: encryptedCount, dest: dest + headerLength, destLength: &decryptedCount, flags: &flags)
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memcpy(dest, src, headerLength)
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}
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}
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decryptedPacket.count = headerLength + decryptedCount
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// TODO: validate replay packet id
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return try plain.deserialize(data: decryptedPacket, start: 0, end: nil)
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}
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}
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}
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