From 15574514b7b9a1467c0d182fde932d2293dbf36e Mon Sep 17 00:00:00 2001
From: Parham Saremi <parhaamsaremi@gmail.com>
Date: Mon, 21 Nov 2022 14:44:13 +0330
Subject: [PATCH] Network,TorHandshakes: handle handshake fail

Previously, TorHandshakes used failwith to raise handshake
failed error. Since we need to catch it, as a result of
replacing generic try-with, this we had to define its special
excpetion and catch that.
---
 NOnion/Exceptions.fs                  |  3 +++
 NOnion/Network/TorGuard.fs            | 26 +++++++++++++++++++-------
 NOnion/TorHandshakes/FastHandshake.fs |  2 +-
 NOnion/TorHandshakes/NTorHandshake.fs |  2 +-
 4 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/NOnion/Exceptions.fs b/NOnion/Exceptions.fs
index 20c61b25..3a9427bb 100644
--- a/NOnion/Exceptions.fs
+++ b/NOnion/Exceptions.fs
@@ -29,6 +29,9 @@ type CircuitDestroyedException internal (reason: DestroyReason) =
 type CircuitDecryptionFailedException internal () =
     inherit NOnionException(sprintf "Circuit Decryption Failed")
 
+type HandshakeFailedException internal () =
+    inherit NOnionException(sprintf "Key handshake failed!")
+
 type TimeoutErrorException internal () =
     inherit NOnionException("Time limit exceeded for operation")
 
diff --git a/NOnion/Network/TorGuard.fs b/NOnion/Network/TorGuard.fs
index 4bdcdb13..b5e90d4f 100644
--- a/NOnion/Network/TorGuard.fs
+++ b/NOnion/Network/TorGuard.fs
@@ -193,6 +193,18 @@ type TorGuard private (client: TcpClient, sslStream: SslStream) =
     member self.SendAsync (circuidId: uint16) (cellToSend: ICell) =
         self.Send circuidId cellToSend |> Async.StartAsTask
 
+    member private self.HandleIncomingCellException<'T when 'T :> NOnionException>
+        (cell: ICell)
+        (ex: 'T)
+        =
+        sprintf
+            "TorGuard: exception when trying to handle incoming cell type=%i, ex=%s"
+            cell.Command
+            (ex.ToString())
+        |> TorLogger.Log
+
+        self.KillChildCircuits()
+
     member private __.ReceiveInternal() =
         async {
             (*
@@ -332,14 +344,14 @@ type TorGuard private (client: TcpClient, sslStream: SslStream) =
                             try
                                 do! circuit.HandleIncomingCell cell
                             with
+                            | :? HandshakeFailedException as ex ->
+                                self.HandleIncomingCellException<HandshakeFailedException>
+                                    cell
+                                    ex
                             | :? CircuitDecryptionFailedException as ex ->
-                                sprintf
-                                    "TorGuard: exception when trying to handle incoming cell type=%i, ex=%s"
-                                    cell.Command
-                                    (ex.ToString())
-                                |> TorLogger.Log
-
-                                self.KillChildCircuits()
+                                self.HandleIncomingCellException<CircuitDecryptionFailedException>
+                                    cell
+                                    ex
                             | ex -> return raise <| FSharpUtil.ReRaise ex
                         | None ->
                             self.KillChildCircuits()
diff --git a/NOnion/TorHandshakes/FastHandshake.fs b/NOnion/TorHandshakes/FastHandshake.fs
index bc2fe4ee..173072ee 100644
--- a/NOnion/TorHandshakes/FastHandshake.fs
+++ b/NOnion/TorHandshakes/FastHandshake.fs
@@ -36,6 +36,6 @@ type FastHandshake =
                 |> Kdf.ComputeLegacyKdf
 
             if kdfResult.KeyHandshake <> serverSideData.DerivativeKey then
-                failwith "Key handshake failed!"
+                raise <| HandshakeFailedException()
             else
                 kdfResult
diff --git a/NOnion/TorHandshakes/NTorHandshake.fs b/NOnion/TorHandshakes/NTorHandshake.fs
index 9f88a43a..0564acb5 100644
--- a/NOnion/TorHandshakes/NTorHandshake.fs
+++ b/NOnion/TorHandshakes/NTorHandshake.fs
@@ -107,6 +107,6 @@ type NTorHandshake =
             let auth = calculateHmacSha256 authInput Constants.NTorTMac
 
             if auth <> serverSideData.DerivativeKey then
-                failwith "Key handshake failed!"
+                raise <| HandshakeFailedException()
             else
                 Kdf.ComputeRfc5869Kdf secretInput