Shut down when server pushes compression enabled

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Override DNS servers client side. [#56](https://github.com/keeshux/tunnelkit/pull/56)
+- Shut down if server pushes a compression directive.
 
 ### Changed
 

TunnelKit/Sources/Core/SessionError.swift

@@ -70,6 +70,9 @@ public enum SessionError: String, Error {
     
     /// The session reached a stale state and can't be recovered.
     case staleSession
+
+    /// Server uses compression.
+    case serverCompression
 }
 
 extension Error {

TunnelKit/Sources/Core/SessionProxy.swift

@@ -905,6 +905,11 @@ public class SessionProxy {
             }
             reply = optionalReply
             log.debug("Received PUSH_REPLY: \"\(reply.maskedDescription)\"")
+            
+            if let framing = reply.compressionFraming, reply.usesCompression {
+                log.error("Server has compression enabled and this is currently unsupported (\(framing))")
+                throw SessionError.serverCompression
+            }
         } catch let e {
             deferStop(.shutdown, e)
             return