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Rework DNS and routes in network extension 

The DNS resolver prior had useless comments, awful nesting, converted
bytes into strings and back into bytes, and generally made no sense.
That's been rewritten now.

But more fundumentally, this commit made the DNS resolver actually
accomplish its objective, by passing AI_ALL to it. It turns out, though,
that the Go library isn't actually using GAI in the way we need for
parsing IP addresses, so we actually need to do another round, this time
with hints flag as zero, so that we get the DNS64 address.

Additionally, since we're now binding sockets to interfaces, we can
entirely remove the excludedRoutes logic.
This commit is contained in:
Jason A. Donenfeld 2018-12-28 19:34:31 +01:00
parent 1de0f5746c
commit 013d603109
3 changed files with 77 additions and 92 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

129
WireGuard/WireGuardNetworkExtension/DNSResolver.swift
View File

@ -45,7 +45,6 @@ class DNSResolver {
let resolvedEndpoint = tuple.1
if let endpoint = endpoint {
if resolvedEndpoint == nil {
// DNS resolution failed
guard let hostname = endpoint.hostname() else { fatalError() }
hostnamesWithDnsResolutionFailure.append(hostname)
}
@ -57,81 +56,97 @@ class DNSResolver {
}
return resolvedEndpoints
}
}
extension DNSResolver {
// Based on DNS resolution code by Jason Donenfeld <jason@zx2c4.com>
// in parse_endpoint() in src/tools/config.c in the WireGuard codebase
//swiftlint:disable:next cyclomatic_complexity
private static func resolveSync(endpoint: Endpoint) -> Endpoint? {
switch endpoint.host {
case .name(let name, _):
var resultPointer = UnsafeMutablePointer<addrinfo>(OpaquePointer(bitPattern: 0))
var hints = addrinfo(
ai_flags: AI_ALL, // We set this to ALL so that we get v4 addresses even on DNS64 networks
ai_family: AF_UNSPEC,
ai_socktype: SOCK_DGRAM,
ai_protocol: IPPROTO_UDP,
ai_addrlen: 0,
ai_canonname: nil,
ai_addr: nil,
ai_next: nil)
if getaddrinfo(name, "\(endpoint.port)", &hints, &resultPointer) != 0 {
return nil
}
var next = resultPointer
var ipv4Address: IPv4Address?
var ipv6Address: IPv6Address?
while next != nil {
let result = next!.pointee
next = result.ai_next
if result.ai_family == AF_INET && result.ai_addrlen == MemoryLayout<sockaddr_in>.size {
var sa4 = UnsafeRawPointer(result.ai_addr)!.assumingMemoryBound(to: sockaddr_in.self).pointee
ipv4Address = IPv4Address(Data(bytes: &sa4.sin_addr, count: MemoryLayout<in_addr>.size))
break // If we found an IPv4 address, we can stop
} else if result.ai_family == AF_INET6 && result.ai_addrlen == MemoryLayout<sockaddr_in6>.size {
var sa6 = UnsafeRawPointer(result.ai_addr)!.assumingMemoryBound(to: sockaddr_in6.self).pointee
ipv6Address = IPv6Address(Data(bytes: &sa6.sin6_addr, count: MemoryLayout<in6_addr>.size))
continue // If we already have an IPv6 address, we can skip this one
}
}
freeaddrinfo(resultPointer)
// The endpoint is a hostname and needs DNS resolution
if addressInfo(for: name, port: endpoint.port, resultPointer: &resultPointer) == 0 {
// getaddrinfo succeeded
let ipv4Buffer = UnsafeMutablePointer<Int8>.allocate(capacity: Int(INET_ADDRSTRLEN))
let ipv6Buffer = UnsafeMutablePointer<Int8>.allocate(capacity: Int(INET6_ADDRSTRLEN))
var ipv4AddressString: String?
var ipv6AddressString: String?
while resultPointer != nil {
let result = resultPointer!.pointee
resultPointer = result.ai_next
if result.ai_family == AF_INET && result.ai_addrlen == MemoryLayout<sockaddr_in>.size {
var sa4 = UnsafeRawPointer(result.ai_addr)!.assumingMemoryBound(to: sockaddr_in.self).pointee
if inet_ntop(result.ai_family, &sa4.sin_addr, ipv4Buffer, socklen_t(INET_ADDRSTRLEN)) != nil {
ipv4AddressString = String(cString: ipv4Buffer)
// If we found an IPv4 address, we can stop
break
}
} else if result.ai_family == AF_INET6 && result.ai_addrlen == MemoryLayout<sockaddr_in6>.size {
if ipv6AddressString != nil {
// If we already have an IPv6 address, we can skip this one
continue
}
var sa6 = UnsafeRawPointer(result.ai_addr)!.assumingMemoryBound(to: sockaddr_in6.self).pointee
if inet_ntop(result.ai_family, &sa6.sin6_addr, ipv6Buffer, socklen_t(INET6_ADDRSTRLEN)) != nil {
ipv6AddressString = String(cString: ipv6Buffer)
}
}
}
ipv4Buffer.deallocate()
ipv6Buffer.deallocate()
// We prefer an IPv4 address over an IPv6 address
if let ipv4AddressString = ipv4AddressString, let ipv4Address = IPv4Address(ipv4AddressString) {
return Endpoint(host: .ipv4(ipv4Address), port: endpoint.port)
} else if let ipv6AddressString = ipv6AddressString, let ipv6Address = IPv6Address(ipv6AddressString) {
return Endpoint(host: .ipv6(ipv6Address), port: endpoint.port)
} else {
return nil
}
// We prefer an IPv4 address over an IPv6 address
if let ipv4Address = ipv4Address {
return Endpoint(host: .ipv4(ipv4Address), port: endpoint.port)
} else if let ipv6Address = ipv6Address {
return Endpoint(host: .ipv6(ipv6Address), port: endpoint.port)
} else {
// getaddrinfo failed
return nil
}
default:
// The endpoint is already resolved
return endpoint
}
}
}
private static func addressInfo(for name: String, port: NWEndpoint.Port, resultPointer: inout UnsafeMutablePointer<addrinfo>?) -> Int32 {
extension Endpoint {
func withReresolvedIP() -> Endpoint {
var ret = self
let hostname: String
switch host {
case .name(let name, _):
hostname = name
case .ipv4(let address):
hostname = "\(address)"
case .ipv6(let address):
hostname = "\(address)"
}
var resultPointer = UnsafeMutablePointer<addrinfo>(OpaquePointer(bitPattern: 0))
var hints = addrinfo(
ai_flags: 0,
ai_flags: 0, // We set this to zero so that we actually resolve this using DNS64
ai_family: AF_UNSPEC,
ai_socktype: SOCK_DGRAM, // WireGuard is UDP-only
ai_protocol: IPPROTO_UDP, // WireGuard is UDP-only
ai_socktype: SOCK_DGRAM,
ai_protocol: IPPROTO_UDP,
ai_addrlen: 0,
ai_canonname: nil,
ai_addr: nil,
ai_next: nil)
return getaddrinfo(
name.cString(using: .utf8), // Hostname
"\(port)".cString(using: .utf8), // Port
&hints,
&resultPointer)
if getaddrinfo(hostname, "\(port)", &hints, &resultPointer) != 0 || resultPointer == nil {
return ret
}
let result = resultPointer!.pointee
if result.ai_family == AF_INET && result.ai_addrlen == MemoryLayout<sockaddr_in>.size {
var sa4 = UnsafeRawPointer(result.ai_addr)!.assumingMemoryBound(to: sockaddr_in.self).pointee
let addr = IPv4Address(Data(bytes: &sa4.sin_addr, count: MemoryLayout<in_addr>.size))
ret = Endpoint(host: .ipv4(addr!), port: port)
} else if result.ai_family == AF_INET6 && result.ai_addrlen == MemoryLayout<sockaddr_in6>.size {
var sa6 = UnsafeRawPointer(result.ai_addr)!.assumingMemoryBound(to: sockaddr_in6.self).pointee
let addr = IPv6Address(Data(bytes: &sa6.sin6_addr, count: MemoryLayout<in6_addr>.size))
ret = Endpoint(host: .ipv6(addr!), port: port)
}
freeaddrinfo(resultPointer)
if ret.host != host {
wg_log(.debug, message: "DNS64: mapped \(host) to \(ret.host)")
} else {
wg_log(.debug, message: "DNS64: mapped \(host) to itself.")
}
return ret
}
}

2
WireGuard/WireGuardNetworkExtension/PacketTunnelProvider.swift
View File

@ -17,6 +17,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
networkMonitor?.cancel()
}
//swiftlint:disable:next function_body_length
override func startTunnel(options: [String: NSObject]?, completionHandler startTunnelCompletionHandler: @escaping (Error?) -> Void) {
let activationAttemptId = options?["activationAttemptId"] as? String
let errorNotifier = ErrorNotifier(activationAttemptId: activationAttemptId)
@ -65,6 +66,7 @@ class PacketTunnelProvider: NEPacketTunnelProvider {
if getsockopt(fileDescriptor, 2 /* SYSPROTO_CONTROL */, 2 /* UTUN_OPT_IFNAME */, ifnamePtr, &ifnameSize) == 0 {
self.ifname = String(cString: ifnamePtr)
}
ifnamePtr.deallocate()
wg_log(.info, message: "Tunnel interface is \(self.ifname ?? "unknown")")
let handle = self.packetTunnelSettingsGenerator!.uapiConfiguration().withGoString { return wgTurnOn($0, fileDescriptor) }
if handle < 0 {

38
WireGuard/WireGuardNetworkExtension/PacketTunnelSettingsGenerator.swift
View File

@ -18,7 +18,7 @@ class PacketTunnelSettingsGenerator {
var wgSettings = ""
for (index, peer) in tunnelConfiguration.peers.enumerated() {
wgSettings.append("public_key=\(peer.publicKey.hexEncodedString())\n")
if let endpoint = resolvedEndpoints[index] {
if let endpoint = resolvedEndpoints[index]?.withReresolvedIP() {
if case .name(_, _) = endpoint.host { assert(false, "Endpoint is not resolved") }
wgSettings.append("endpoint=\(endpoint.stringRepresentation)\n")
}
@ -42,7 +42,7 @@ class PacketTunnelSettingsGenerator {
if let preSharedKey = peer.preSharedKey {
wgSettings.append("preshared_key=\(preSharedKey.hexEncodedString())\n")
}
if let endpoint = resolvedEndpoints[index] {
if let endpoint = resolvedEndpoints[index]?.withReresolvedIP() {
if case .name(_, _) = endpoint.host { assert(false, "Endpoint is not resolved") }
wgSettings.append("endpoint=\(endpoint.stringRepresentation)\n")
}
@ -63,18 +63,7 @@ class PacketTunnelSettingsGenerator {
* make sense. So, we fill it in with this placeholder, which is not
* a valid IP address that will actually route over the Internet.
*/
var remoteAddress = "0.0.0.0"
let endpointsCompact = resolvedEndpoints.compactMap { $0 }
if endpointsCompact.count == 1 {
switch endpointsCompact.first!.host {
case .ipv4(let address):
remoteAddress = "\(address)"
case .ipv6(let address):
remoteAddress = "\(address)"
default:
break
}
}
let remoteAddress = "0.0.0.0"
let networkSettings = NEPacketTunnelNetworkSettings(tunnelRemoteAddress: remoteAddress)
@ -93,16 +82,13 @@ class PacketTunnelSettingsGenerator {
let (ipv4Routes, ipv6Routes) = routes()
let (ipv4IncludedRoutes, ipv6IncludedRoutes) = includedRoutes()
let (ipv4ExcludedRoutes, ipv6ExcludedRoutes) = excludedRoutes()
let ipv4Settings = NEIPv4Settings(addresses: ipv4Routes.map { $0.destinationAddress }, subnetMasks: ipv4Routes.map { $0.destinationSubnetMask })
ipv4Settings.includedRoutes = ipv4IncludedRoutes
ipv4Settings.excludedRoutes = ipv4ExcludedRoutes
networkSettings.ipv4Settings = ipv4Settings
let ipv6Settings = NEIPv6Settings(addresses: ipv6Routes.map { $0.destinationAddress }, networkPrefixLengths: ipv6Routes.map { $0.destinationNetworkPrefixLength })
ipv6Settings.includedRoutes = ipv6IncludedRoutes
ipv6Settings.excludedRoutes = ipv6ExcludedRoutes
networkSettings.ipv6Settings = ipv6Settings
return networkSettings
@ -152,24 +138,6 @@ class PacketTunnelSettingsGenerator {
}
return (ipv4IncludedRoutes, ipv6IncludedRoutes)
}
private func excludedRoutes() -> ([NEIPv4Route], [NEIPv6Route]) {
var ipv4ExcludedRoutes = [NEIPv4Route]()
var ipv6ExcludedRoutes = [NEIPv6Route]()
for endpoint in resolvedEndpoints {
guard let endpoint = endpoint else { continue }
switch endpoint.host {
case .ipv4(let address):
ipv4ExcludedRoutes.append(NEIPv4Route(destinationAddress: "\(address)", subnetMask: "255.255.255.255"))
case .ipv6(let address):
ipv6ExcludedRoutes.append(NEIPv6Route(destinationAddress: "\(address)", networkPrefixLength: NSNumber(value: UInt8(128))))
default:
fatalError()
}
}
return (ipv4ExcludedRoutes, ipv6ExcludedRoutes)
}
}
private extension Data {