wireguard-apple/WireGuard/WireGuardNetworkExtension/PacketTunnelSettingsGenerat...

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// SPDX-License-Identifier: MIT
// Copyright © 2018-2019 WireGuard LLC. All Rights Reserved.
import Foundation
import Network
import NetworkExtension
class PacketTunnelSettingsGenerator {
let tunnelConfiguration: TunnelConfiguration
let resolvedEndpoints: [Endpoint?]
init(tunnelConfiguration: TunnelConfiguration, resolvedEndpoints: [Endpoint?]) {
self.tunnelConfiguration = tunnelConfiguration
self.resolvedEndpoints = resolvedEndpoints
}
func endpointUapiConfiguration() -> String {
var wgSettings = ""
for (index, peer) in tunnelConfiguration.peers.enumerated() {
if let publicKey = peer.publicKey.hexKey() {
wgSettings.append("public_key=\(publicKey)\n")
}
if let endpoint = resolvedEndpoints[index]?.withReresolvedIP() {
if case .name(_, _) = endpoint.host { assert(false, "Endpoint is not resolved") }
wgSettings.append("endpoint=\(endpoint.stringRepresentation)\n")
}
}
return wgSettings
}
func uapiConfiguration() -> String {
var wgSettings = ""
if let privateKey = tunnelConfiguration.interface.privateKey.hexKey() {
wgSettings.append("private_key=\(privateKey)\n")
}
if let listenPort = tunnelConfiguration.interface.listenPort {
wgSettings.append("listen_port=\(listenPort)\n")
}
if !tunnelConfiguration.peers.isEmpty {
wgSettings.append("replace_peers=true\n")
}
assert(tunnelConfiguration.peers.count == resolvedEndpoints.count)
for (index, peer) in tunnelConfiguration.peers.enumerated() {
if let publicKey = peer.publicKey.hexKey() {
wgSettings.append("public_key=\(publicKey)\n")
}
if let preSharedKey = peer.preSharedKey?.hexKey() {
wgSettings.append("preshared_key=\(preSharedKey)\n")
}
if let endpoint = resolvedEndpoints[index]?.withReresolvedIP() {
if case .name(_, _) = endpoint.host { assert(false, "Endpoint is not resolved") }
wgSettings.append("endpoint=\(endpoint.stringRepresentation)\n")
}
let persistentKeepAlive = peer.persistentKeepAlive ?? 0
wgSettings.append("persistent_keepalive_interval=\(persistentKeepAlive)\n")
if !peer.allowedIPs.isEmpty {
wgSettings.append("replace_allowed_ips=true\n")
peer.allowedIPs.forEach { wgSettings.append("allowed_ip=\($0.stringRepresentation)\n") }
}
}
return wgSettings
}
func generateNetworkSettings() -> NEPacketTunnelNetworkSettings {
/* iOS requires a tunnel endpoint, whereas in WireGuard it's valid for
* a tunnel to have no endpoint, or for there to be many endpoints, in
* which case, displaying a single one in settings doesn't really
* make sense. So, we fill it in with this placeholder, which is not
* a valid IP address that will actually route over the Internet.
*/
let networkSettings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: "127.0.0.1")
let dnsServerStrings = tunnelConfiguration.interface.dns.map { $0.stringRepresentation }
let dnsSettings = NEDNSSettings(servers: dnsServerStrings)
dnsSettings.matchDomains = [""] // All DNS queries must first go through the tunnel's DNS
networkSettings.dnsSettings = dnsSettings
let mtu = tunnelConfiguration.interface.mtu ?? 0
/* 0 means automatic MTU. In theory, we should just do
* `networkSettings.tunnelOverheadBytes = 80` but in
* practice there are too many broken networks out there.
* Instead set it to 1280. Boohoo. Maybe someday we'll
* add a nob, maybe, or iOS will do probing for us.
*/
if mtu == 0 {
#if os(iOS)
networkSettings.mtu = NSNumber(value: 1280)
#elseif os(macOS)
networkSettings.tunnelOverheadBytes = 80
#else
#error("Unimplemented")
#endif
} else {
networkSettings.mtu = NSNumber(value: mtu)
}
let (ipv4Routes, ipv6Routes) = routes()
let (ipv4IncludedRoutes, ipv6IncludedRoutes) = includedRoutes()
let ipv4Settings = NEIPv4Settings(addresses: ipv4Routes.map { $0.destinationAddress }, subnetMasks: ipv4Routes.map { $0.destinationSubnetMask })
ipv4Settings.includedRoutes = ipv4IncludedRoutes
networkSettings.ipv4Settings = ipv4Settings
let ipv6Settings = NEIPv6Settings(addresses: ipv6Routes.map { $0.destinationAddress }, networkPrefixLengths: ipv6Routes.map { $0.destinationNetworkPrefixLength })
ipv6Settings.includedRoutes = ipv6IncludedRoutes
networkSettings.ipv6Settings = ipv6Settings
return networkSettings
}
private func ipv4SubnetMaskString(of addressRange: IPAddressRange) -> String {
let length: UInt8 = addressRange.networkPrefixLength
assert(length <= 32)
var octets: [UInt8] = [0, 0, 0, 0]
let subnetMask: UInt32 = length > 0 ? ~UInt32(0) << (32 - length) : UInt32(0)
octets[0] = UInt8(truncatingIfNeeded: subnetMask >> 24)
octets[1] = UInt8(truncatingIfNeeded: subnetMask >> 16)
octets[2] = UInt8(truncatingIfNeeded: subnetMask >> 8)
octets[3] = UInt8(truncatingIfNeeded: subnetMask)
return octets.map { String($0) }.joined(separator: ".")
}
private func routes() -> ([NEIPv4Route], [NEIPv6Route]) {
var ipv4Routes = [NEIPv4Route]()
var ipv6Routes = [NEIPv6Route]()
for addressRange in tunnelConfiguration.interface.addresses {
if addressRange.address is IPv4Address {
ipv4Routes.append(NEIPv4Route(destinationAddress: "\(addressRange.address)", subnetMask: ipv4SubnetMaskString(of: addressRange)))
} else if addressRange.address is IPv6Address {
/* Big fat ugly hack for broken iOS networking stack: the smallest prefix that will have
* any effect on iOS is a /120, so we clamp everything above to /120. This is potentially
* very bad, if various network parameters were actually relying on that subnet being
* intentionally small. TODO: talk about this with upstream iOS devs.
*/
ipv6Routes.append(NEIPv6Route(destinationAddress: "\(addressRange.address)", networkPrefixLength: NSNumber(value: min(120, addressRange.networkPrefixLength))))
}
}
return (ipv4Routes, ipv6Routes)
}
private func includedRoutes() -> ([NEIPv4Route], [NEIPv6Route]) {
var ipv4IncludedRoutes = [NEIPv4Route]()
var ipv6IncludedRoutes = [NEIPv6Route]()
for peer in tunnelConfiguration.peers {
for addressRange in peer.allowedIPs {
if addressRange.address is IPv4Address {
ipv4IncludedRoutes.append(NEIPv4Route(destinationAddress: "\(addressRange.address)", subnetMask: ipv4SubnetMaskString(of: addressRange)))
} else if addressRange.address is IPv6Address {
ipv6IncludedRoutes.append(NEIPv6Route(destinationAddress: "\(addressRange.address)", networkPrefixLength: NSNumber(value: addressRange.networkPrefixLength)))
}
}
}
return (ipv4IncludedRoutes, ipv6IncludedRoutes)
}
}