wireguard-apple/WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift

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//
// Copyright © 2018 WireGuard LLC. All rights reserved.
//
import NetworkExtension
import os.log
enum PacketTunnelProviderError: Error {
case invalidOptions
case couldNotStartWireGuard
case coultNotSetNetworkSettings
}
/// A packet tunnel provider object.
class PacketTunnelProvider: NEPacketTunnelProvider {
// MARK: Properties
private var wgHandle: Int32?
private var wgContext: WireGuardContext?
// MARK: NEPacketTunnelProvider
/// Begin the process of establishing the tunnel.
override func startTunnel(options: [String: NSObject]?,
completionHandler startTunnelCompletionHandler: @escaping (Error?) -> Void) {
os_log("Starting tunnel", log: OSLog.default, type: .info)
guard let options = options else {
startTunnelCompletionHandler(PacketTunnelProviderError.invalidOptions)
return
}
guard let interfaceName = options[.interfaceName] as? String,
let wireguardSettings = options[.wireguardSettings] as? String,
let remoteAddress = options[.remoteAddress] as? String,
let dnsServers = options[.dnsServers] as? [String],
let mtu = options[.mtu] as? NSNumber,
// IPv4 settings
let ipv4Addresses = options[.ipv4Addresses] as? [String],
let ipv4SubnetMasks = options[.ipv4SubnetMasks] as? [String],
let ipv4IncludedRouteAddresses = options[.ipv4IncludedRouteAddresses] as? [String],
let ipv4IncludedRouteSubnetMasks = options[.ipv4IncludedRouteSubnetMasks] as? [String],
let ipv4ExcludedRouteAddresses = options[.ipv4ExcludedRouteAddresses] as? [String],
let ipv4ExcludedRouteSubnetMasks = options[.ipv4ExcludedRouteSubnetMasks] as? [String],
// IPv6 settings
let ipv6Addresses = options[.ipv6Addresses] as? [String],
let ipv6NetworkPrefixLengths = options[.ipv6NetworkPrefixLengths] as? [NSNumber],
let ipv6IncludedRouteAddresses = options[.ipv6IncludedRouteAddresses] as? [String],
let ipv6IncludedRouteNetworkPrefixLengths = options[.ipv6IncludedRouteNetworkPrefixLengths] as? [NSNumber],
let ipv6ExcludedRouteAddresses = options[.ipv6ExcludedRouteAddresses] as? [String],
let ipv6ExcludedRouteNetworkPrefixLengths = options[.ipv6ExcludedRouteNetworkPrefixLengths] as? [NSNumber]
else {
startTunnelCompletionHandler(PacketTunnelProviderError.invalidOptions)
return
}
configureLogger()
wgContext = WireGuardContext(packetFlow: self.packetFlow)
let handle = connect(interfaceName: interfaceName, settings: wireguardSettings, mtu: mtu.uint16Value)
if handle < 0 {
startTunnelCompletionHandler(PacketTunnelProviderError.couldNotStartWireGuard)
return
}
wgHandle = handle
// Network settings
let networkSettings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: remoteAddress)
// IPv4 settings
let ipv4Settings = NEIPv4Settings(addresses: ipv4Addresses, subnetMasks: ipv4SubnetMasks)
assert(ipv4IncludedRouteAddresses.count == ipv4IncludedRouteSubnetMasks.count)
ipv4Settings.includedRoutes = zip(ipv4IncludedRouteAddresses, ipv4IncludedRouteSubnetMasks).map {
NEIPv4Route(destinationAddress: $0.0, subnetMask: $0.1)
}
assert(ipv4ExcludedRouteAddresses.count == ipv4ExcludedRouteSubnetMasks.count)
ipv4Settings.excludedRoutes = zip(ipv4ExcludedRouteAddresses, ipv4ExcludedRouteSubnetMasks).map {
NEIPv4Route(destinationAddress: $0.0, subnetMask: $0.1)
}
networkSettings.ipv4Settings = ipv4Settings
// IPv6 settings
let ipv6Settings = NEIPv6Settings(addresses: ipv6Addresses, networkPrefixLengths: ipv6NetworkPrefixLengths)
assert(ipv6IncludedRouteAddresses.count == ipv6IncludedRouteNetworkPrefixLengths.count)
ipv6Settings.includedRoutes = zip(ipv6IncludedRouteAddresses, ipv6IncludedRouteNetworkPrefixLengths).map {
NEIPv6Route(destinationAddress: $0.0, networkPrefixLength: $0.1)
}
assert(ipv6ExcludedRouteAddresses.count == ipv6ExcludedRouteNetworkPrefixLengths.count)
ipv6Settings.excludedRoutes = zip(ipv6ExcludedRouteAddresses, ipv6ExcludedRouteNetworkPrefixLengths).map {
NEIPv6Route(destinationAddress: $0.0, networkPrefixLength: $0.1)
}
networkSettings.ipv6Settings = ipv6Settings
// DNS
networkSettings.dnsSettings = NEDNSSettings(servers: dnsServers)
// MTU
if (mtu == 0) {
// 0 imples automatic MTU, where we set overhead as 95 bytes,
// 80 for WireGuard and the 15 to make sure WireGuard's padding will work.
networkSettings.tunnelOverheadBytes = 95
} else {
networkSettings.mtu = mtu
}
setTunnelNetworkSettings(networkSettings) { (error) in
if let error = error {
os_log("Error setting network settings: %s", log: OSLog.default, type: .error, error.localizedDescription)
startTunnelCompletionHandler(PacketTunnelProviderError.coultNotSetNetworkSettings)
} else {
startTunnelCompletionHandler(nil /* No errors */)
}
}
}
/// Begin the process of stopping the tunnel.
override func stopTunnel(with reason: NEProviderStopReason, completionHandler: @escaping () -> Void) {
os_log("Stopping tunnel", log: OSLog.default, type: .info)
if let handle = wgHandle {
wgTurnOff(handle)
}
wgContext?.closeTunnel()
completionHandler()
}
private func configureLogger() {
wgSetLogger { (level, tagCStr, msgCStr) in
let logType: OSLogType
switch level {
case 0:
logType = .debug
case 1:
logType = .info
case 2:
logType = .error
default:
logType = .default
}
let tag = (tagCStr != nil) ? String(cString: tagCStr!) : ""
let msg = (msgCStr != nil) ? String(cString: msgCStr!) : ""
os_log("wg log: %{public}s: %{public}s", log: OSLog.default, type: logType, tag, msg)
}
}
private func connect(interfaceName: String, settings: String, mtu: UInt16) -> Int32 { // swiftlint:disable:this cyclomatic_complexity
return withStringsAsGoStrings(interfaceName, settings) { (nameGoStr, settingsGoStr) -> Int32 in
return withUnsafeMutablePointer(to: &wgContext) { (wgCtxPtr) -> Int32 in
return wgTurnOn(nameGoStr, settingsGoStr, mtu, { (wgCtxPtr, buf, len) -> Int in
autoreleasepool {
// read_fn: Read from the TUN interface and pass it on to WireGuard
guard let wgCtxPtr = wgCtxPtr else { return 0 }
guard let buf = buf else { return 0 }
let wgContext = wgCtxPtr.bindMemory(to: WireGuardContext.self, capacity: 1).pointee
var isTunnelClosed = false
guard let packet = wgContext.readPacket(isTunnelClosed: &isTunnelClosed) else { return 0 }
if isTunnelClosed { return -1 }
let packetData = packet.data
if packetData.count <= len {
packetData.copyBytes(to: buf, count: packetData.count)
return packetData.count
}
return 0
}
}, { (wgCtxPtr, buf, len) -> Int in
autoreleasepool {
// write_fn: Receive packets from WireGuard and write to the TUN interface
guard let wgCtxPtr = wgCtxPtr else { return 0 }
guard let buf = buf else { return 0 }
guard len > 0 else { return 0 }
let wgContext = wgCtxPtr.bindMemory(to: WireGuardContext.self, capacity: 1).pointee
let ipVersionBits = (buf[0] & 0xf0) >> 4
let ipVersion: sa_family_t? = {
if ipVersionBits == 4 { return sa_family_t(AF_INET) } // IPv4
if ipVersionBits == 6 { return sa_family_t(AF_INET6) } // IPv6
return nil
}()
guard let protocolFamily = ipVersion else { fatalError("Unknown IP version") }
let packet = NEPacket(data: Data(bytes: buf, count: len), protocolFamily: protocolFamily)
var isTunnelClosed = false
let isWritten = wgContext.writePacket(packet: packet, isTunnelClosed: &isTunnelClosed)
if isTunnelClosed { return -1 }
if isWritten {
return len
}
return 0
}
},
wgCtxPtr)
}
}
}
}
class WireGuardContext {
private var packetFlow: NEPacketTunnelFlow
private var outboundPackets: [NEPacket] = []
private var isTunnelClosed: Bool = false
private var readPacketCondition = NSCondition()
init(packetFlow: NEPacketTunnelFlow) {
self.packetFlow = packetFlow
}
func closeTunnel() {
isTunnelClosed = true
readPacketCondition.signal()
}
func packetsRead(packets: [NEPacket]) {
readPacketCondition.lock()
outboundPackets.append(contentsOf: packets)
readPacketCondition.unlock()
readPacketCondition.signal()
}
func readPacket(isTunnelClosed: inout Bool) -> NEPacket? {
if outboundPackets.isEmpty {
readPacketCondition.lock()
packetFlow.readPacketObjects(completionHandler: packetsRead)
while outboundPackets.isEmpty && !self.isTunnelClosed {
readPacketCondition.wait()
}
readPacketCondition.unlock()
}
isTunnelClosed = self.isTunnelClosed
if !outboundPackets.isEmpty {
return outboundPackets.removeFirst()
}
return nil
}
func writePacket(packet: NEPacket, isTunnelClosed: inout Bool) -> Bool {
isTunnelClosed = self.isTunnelClosed
return packetFlow.writePacketObjects([packet])
}
}
private func withStringsAsGoStrings<R>(_ str1: String, _ str2: String, closure: (gostring_t, gostring_t) -> R) -> R {
return str1.withCString { (s1cStr) -> R in
let gstr1 = gostring_t(p: s1cStr, n: str1.utf8.count)
return str2.withCString { (s2cStr) -> R in
let gstr2 = gostring_t(p: s2cStr, n: str2.utf8.count)
return closure(gstr1, gstr2)
}
}
}