From 037f08ed62018a32930238429829e7e6a892bf35 Mon Sep 17 00:00:00 2001
From: Davide De Rosa <keeshux@gmail.com>
Date: Wed, 1 May 2019 10:37:39 +0200
Subject: [PATCH] Retry auth once without local options

Hack around picky server implementations.

Fixes #95
---
 CHANGELOG.md                                  |  6 ++
 .../Core/SessionProxy+Authenticator.swift     | 62 +++++++++++--------
 TunnelKit/Sources/Core/SessionProxy.swift     | 13 ++++
 3 files changed, 54 insertions(+), 27 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bfb60fa..7f9ff43 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+- Authentication failure due to local options. [#95](https://github.com/keeshux/tunnelkit/issues/95)
+
 ## 1.7.0 (2019-04-28)
 
 ### Changed
diff --git a/TunnelKit/Sources/Core/SessionProxy+Authenticator.swift b/TunnelKit/Sources/Core/SessionProxy+Authenticator.swift
index 149741b..b5a7a50 100644
--- a/TunnelKit/Sources/Core/SessionProxy+Authenticator.swift
+++ b/TunnelKit/Sources/Core/SessionProxy+Authenticator.swift
@@ -66,6 +66,8 @@ extension SessionProxy {
         
         let password: ZeroingData?
         
+        var withLocalOptions: Bool
+        
         init(_ username: String?, _ password: String?) throws {
             preMaster = try SecureRandom.safeData(length: CoreConfiguration.preMasterLength)
             random1 = try SecureRandom.safeData(length: CoreConfiguration.randomLength)
@@ -80,6 +82,8 @@ extension SessionProxy {
                 self.password = nil
             }
             
+            withLocalOptions = true
+            
             controlBuffer = Z()
         }
         
@@ -95,35 +99,39 @@ extension SessionProxy {
             raw.append(random2)
             
             // options string
-            var opts = [
-                "V4",
-                "dev-type tun"
-            ]
-            //////
-            if let comp = options.compressionFraming {
-                switch comp {
-                case .compLZO:
-                    opts.append("comp-lzo")
-                    
-                case .compress:
-                    opts.append("compress")
-                    
-                default:
-                    break
+            let optsString: String
+            if withLocalOptions {
+                var opts = [
+                    "V4",
+                    "dev-type tun"
+                ]
+                if let comp = options.compressionFraming {
+                    switch comp {
+                    case .compLZO:
+                        opts.append("comp-lzo")
+                        
+                    case .compress:
+                        opts.append("compress")
+                        
+                    default:
+                        break
+                    }
                 }
+                if let direction = options.tlsWrap?.key.direction?.rawValue {
+                    opts.append("keydir \(direction)")
+                }
+                opts.append("cipher \(options.cipher?.rawValue ?? "BF-CBC")")
+                opts.append("auth \(options.fallbackDigest.rawValue)")
+                opts.append("keysize \(options.fallbackCipher.keySize)")
+                if let strategy = options.tlsWrap?.strategy {
+                    opts.append("tls-\(strategy)")
+                }
+                opts.append("key-method 2")
+                opts.append("tls-client")
+                optsString = opts.joined(separator: ",")
+            } else {
+                optsString = "V0 UNDEF"
             }
-            if let direction = options.tlsWrap?.key.direction?.rawValue {
-                opts.append("keydir \(direction)")
-            }
-            opts.append("cipher \(options.cipher?.rawValue ?? "BF-CBC")")
-            opts.append("auth \(options.fallbackDigest.rawValue)")
-            opts.append("keysize \(options.fallbackCipher.keySize)")
-            if let strategy = options.tlsWrap?.strategy {
-                opts.append("tls-\(strategy)")
-            }
-            opts.append("key-method 2")
-            opts.append("tls-client")
-            let optsString = opts.joined(separator: ",")
             log.debug("TLS.auth: Local options: \(optsString)")
             raw.appendSized(Z(optsString, nullTerminated: true))
             
diff --git a/TunnelKit/Sources/Core/SessionProxy.swift b/TunnelKit/Sources/Core/SessionProxy.swift
index 4e40387..a655291 100644
--- a/TunnelKit/Sources/Core/SessionProxy.swift
+++ b/TunnelKit/Sources/Core/SessionProxy.swift
@@ -105,6 +105,8 @@ public class SessionProxy {
     private let queue: DispatchQueue
 
     private var tlsObserver: NSObjectProtocol?
+    
+    private var withLocalOptions: Bool
 
     private var keys: [UInt8: SessionKey]
 
@@ -190,6 +192,7 @@ public class SessionProxy {
         self.configuration = configuration
         self.cachesURL = cachesURL
 
+        withLocalOptions = true
         keys = [:]
         oldKeys = []
         negotiationKeyIdx = 0
@@ -676,6 +679,7 @@ public class SessionProxy {
         
         do {
             authenticator = try Authenticator(credentials?.username, pushReply?.options.authToken ?? credentials?.password)
+            authenticator?.withLocalOptions = withLocalOptions
             try authenticator?.putAuth(into: negotiationKey.tls, options: configuration)
         } catch let e {
             deferStop(.shutdown, e)
@@ -908,6 +912,15 @@ public class SessionProxy {
     // Ruby: handle_ctrl_msg
     private func handleControlMessage(_ message: String) {
         guard !message.hasPrefix("AUTH_FAILED") else {
+
+            // XXX: retry without client options
+            if authenticator?.withLocalOptions ?? false {
+                log.warning("Authentication failure, retrying without local options")
+                withLocalOptions = false
+                deferStop(.reconnect, SessionError.badCredentials)
+                return
+            }
+
             deferStop(.shutdown, SessionError.badCredentials)
             return
         }