Make peerInfo dynamic to add IV_CIPHERS

Fixes #193

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
+
+### Added
+
+- Handle `--data-ciphers` from OpenVPN 2.5
+
 ## 3.2.0 (2021-01-07)
 
 ### Changed

TunnelKit/Sources/Protocols/OpenVPN/Authenticator.swift

@@ -156,7 +156,11 @@ extension OpenVPN {
             }
 
             // peer info
-            raw.appendSized(Z(CoreConfiguration.OpenVPN.peerInfo, nullTerminated: true))
+            var extra: [String: String] = [:]
+            if let dataCiphers = options.dataCiphers {
+                extra["IV_CIPHERS"] = dataCiphers.map { $0.rawValue }.joined(separator: ":")
+            }
+            raw.appendSized(Z(CoreConfiguration.OpenVPN.peerInfo(extra: extra), nullTerminated: true))
 
             if CoreConfiguration.logsSensitiveData {
                 log.debug("TLS.auth: Put plaintext (\(raw.count) bytes): \(raw.toHex())")

TunnelKit/Sources/Protocols/OpenVPN/CoreConfiguration+OpenVPN.swift

@@ -63,7 +63,7 @@ extension CoreConfiguration {
         
         // MARK: Authentication
         
-        static let peerInfo: String = {
+        static func peerInfo(extra: [String: String]? = nil) -> String {
             let platform: String
             #if os(iOS)
             platform = "ios"
@@ -83,9 +83,12 @@ extension CoreConfiguration {
             if LZOIsSupported() {
                 info.append("IV_LZO=1")
             }
+            if let extra = extra {
+                info.append(contentsOf: extra.map { "\($0)=\($1)" })
+            }
             info.append("")
             return info.joined(separator: "\n")
-        }()
+        }
         
         static let randomLength = 32