From 08c293b4050441d3169d9f4de0171241bd291832 Mon Sep 17 00:00:00 2001
From: Karl Mikaelsson <derfian@cendio.se>
Date: Fri, 2 Feb 2018 17:13:36 +0100
Subject: [PATCH] Fix Fast-Path PDU decryption regression

This solves a problem where rdesktop would get really confused about
the data read from the server and crash in random places just after
connecting.
---
 secure.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/secure.c b/secure.c
index b829a02..6443c6e 100644
--- a/secure.c
+++ b/secure.c
@@ -844,7 +844,7 @@ sec_process_mcs_data(STREAM s)
 STREAM
 sec_recv(RD_BOOL *is_fastpath)
 {
-	uint8 fastpath_hdr;
+	uint8 fastpath_hdr, fastpath_flags;
 	uint16 sec_flags;
 	uint16 channel;
 	STREAM s;
@@ -855,7 +855,9 @@ sec_recv(RD_BOOL *is_fastpath)
 		{
 			/* If fastpath packet is encrypted, read data
 			   signature and decrypt */
-			if (fastpath_hdr & FASTPATH_OUTPUT_ENCRYPTED)
+			/* FIXME: extracting flags from hdr could be made less obscure */
+			fastpath_flags = (fastpath_hdr & 0xC0) >> 6;
+			if (fastpath_flags & FASTPATH_OUTPUT_ENCRYPTED)
 			{
 				in_uint8s(s, 8);	/* signature */
 				sec_decrypt(s->p, s->end - s->p);