From 008dc6c7856a1292f8049f33c675c4a9f2246e49 Mon Sep 17 00:00:00 2001
From: Ludvig Strigeus <strigeus@gmail.com>
Date: Mon, 10 Dec 2018 23:46:59 +0100
Subject: [PATCH] Vary keepalive timeout when obfuscation is active

---
 wireguard_proto.cpp | 7 ++++++-
 wireguard_proto.h   | 3 ++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/wireguard_proto.cpp b/wireguard_proto.cpp
index 49af3fb..ca053df 100644
--- a/wireguard_proto.cpp
+++ b/wireguard_proto.cpp
@@ -350,6 +350,7 @@ WgPeer::WgPeer(WgDevice *dev) {
   last_handshake_init_recv_timestamp_ = 0;
   last_complete_handskake_timestamp_ = 0;
   persistent_keepalive_ms_ = 0;
+  keepalive_timeout_ms_ = KEEPALIVE_TIMEOUT_MS;
   rx_bytes_ = 0;
   tx_bytes_ = 0;
   timers_ = 0;
@@ -1178,7 +1179,11 @@ uint32 WgPeer::CheckTimeouts_Locked(uint64 now) {
         rv |= ACTION_SEND_HANDSHAKE;
       }
     }
-    if ((t & (1 << TIMER_SEND_KEEPALIVE)) && (now32 - timer_value_[TIMER_SEND_KEEPALIVE]) >= KEEPALIVE_TIMEOUT_MS) {
+    if ((t & (1 << TIMER_SEND_KEEPALIVE)) && (now32 - timer_value_[TIMER_SEND_KEEPALIVE]) >= keepalive_timeout_ms_) {
+      // When header obfuscation is enabled, vary this between 7,8,9,10,11,12
+      if (WITH_HEADER_OBFUSCATION && dev_->packet_obfuscator().enabled())
+        keepalive_timeout_ms_ = KEEPALIVE_TIMEOUT_MS + ((int)(dev_->GetRandomNumber() % 6) - 3) * 1000;
+
       t &= ~(1 << TIMER_SEND_KEEPALIVE);
       rv |= ACTION_SEND_KEEPALIVE;
       if (pending_keepalive_) {
diff --git a/wireguard_proto.h b/wireguard_proto.h
index 7049e82..1471036 100644
--- a/wireguard_proto.h
+++ b/wireguard_proto.h
@@ -60,7 +60,6 @@ enum ProtocolTimeouts {
   KEEPALIVE_TIMEOUT_MS = 10000,
   REKEY_AFTER_TIME_MS = 120000,
   REJECT_AFTER_TIME_MS = 180000,
-  PERSISTENT_KEEPALIVE_MS = 25000,
   MIN_HANDSHAKE_INTERVAL_MS = 20,
 
   MAX_SIZE_OF_HANDSHAKE_EXTENSION = 1024,
@@ -650,6 +649,8 @@ private:
   uint8 num_ciphers_;
   uint8 ciphers_[MAX_CIPHERS];
 
+  uint32 keepalive_timeout_ms_; // Set to KEEPALIVE_TIMEOUT_MS
+
   uint64 rx_bytes_;
   uint64 tx_bytes_;