From cb55a025997776cec2ae7812221c67eb186f8463 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Tue, 22 Jan 2019 17:42:09 -0800
Subject: [PATCH] Fix parsing XOR-MAPPED-ADDRESS if the optional comprehension
 bit is set

---
 mist/stun.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mist/stun.cpp b/mist/stun.cpp
index b8ffc3b..987b97e 100644
--- a/mist/stun.cpp
+++ b/mist/stun.cpp
@@ -179,7 +179,8 @@ bool getExternalAddressPortIP4(int proto, unsigned short localPort, PSOCKADDR_IN
             printf("STUN attribute out of bounds: %d\n", htons(attribute->length));
             return false;
         }
-        else if (htons(attribute->type) != STUN_ATTRIBUTE_XOR_MAPPED_ADDRESS) {
+        // Mask off the comprehension bit
+        else if ((htons(attribute->type) & 0x7FFF) != STUN_ATTRIBUTE_XOR_MAPPED_ADDRESS) {
             // Continue searching if this wasn't our address
             bytesRead -= sizeof(*attribute) + htons(attribute->length);
             attribute = (PSTUN_ATTRIBUTE_HEADER)(((char*)attribute) + sizeof(*attribute) + htons(attribute->length));