From da03cf7b41817ca279d38de4e39f3ecf6bda761b Mon Sep 17 00:00:00 2001
From: Vivien Nicolas <vnicolas@apple.com>
Date: Sat, 22 Oct 2022 18:16:33 +0200
Subject: [PATCH] Update PASE/CASE session establishment response timeouts

---
 src/protocols/secure_channel/CASESession.cpp | 17 +++++++++++------
 src/protocols/secure_channel/PASESession.cpp | 17 +++++++++++------
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/protocols/secure_channel/CASESession.cpp b/src/protocols/secure_channel/CASESession.cpp
index 209d8b29101b79..be20add0566da0 100644
--- a/src/protocols/secure_channel/CASESession.cpp
+++ b/src/protocols/secure_channel/CASESession.cpp
@@ -116,10 +116,15 @@ using HKDF_sha_crypto = HKDF_shaHSM;
 using HKDF_sha_crypto = HKDF_sha;
 #endif
 
-// Wait at most 30 seconds for the response from the peer.
-// This timeout value assumes the underlying transport is reliable.
-// The session establishment fails if the response is not received within timeout window.
-static constexpr ExchangeContext::Timeout kSigma_Response_Timeout = System::Clock::Seconds16(30);
+// Amounts of time to allow for server-side processing of messages.
+//
+// This timeout values only allow for the server-side processing and assume that any transport-specific
+// latency will be added to them.
+//
+// The session establishment fails if the response is not received within the resulting timeout window,
+//  which accounts for both transport latency and the server-side latency.
+static constexpr ExchangeContext::Timeout kExpectedLowProcessingTime  = System::Clock::Seconds16(2);
+static constexpr ExchangeContext::Timeout kExpectedHighProcessingTime = System::Clock::Seconds16(30);
 
 CASESession::~CASESession()
 {
@@ -260,7 +265,7 @@ CHIP_ERROR CASESession::EstablishSession(SessionManager & sessionManager, Fabric
     mSessionResumptionStorage = sessionResumptionStorage;
     mLocalMRPConfig           = mrpLocalConfig;
 
-    mExchangeCtxt->SetResponseTimeout(kSigma_Response_Timeout + mExchangeCtxt->GetSessionHandle()->GetAckTimeout());
+    mExchangeCtxt->UseSuggestedResponseTimeout(kExpectedLowProcessingTime);
     mPeerNodeId  = peerScopedNodeId.GetNodeId();
     mLocalNodeId = fabricInfo->GetNodeId();
 
@@ -1723,8 +1728,8 @@ CHIP_ERROR CASESession::ValidateReceivedMessage(ExchangeContext * ec, const Payl
     else
     {
         mExchangeCtxt = ec;
-        mExchangeCtxt->SetResponseTimeout(kSigma_Response_Timeout + mExchangeCtxt->GetSessionHandle()->GetAckTimeout());
     }
+    mExchangeCtxt->UseSuggestedResponseTimeout(kExpectedHighProcessingTime);
 
     VerifyOrReturnError(!msg.IsNull(), CHIP_ERROR_INVALID_ARGUMENT);
     return CHIP_NO_ERROR;
diff --git a/src/protocols/secure_channel/PASESession.cpp b/src/protocols/secure_channel/PASESession.cpp
index 67b462fa860838..dd029e7e669285 100644
--- a/src/protocols/secure_channel/PASESession.cpp
+++ b/src/protocols/secure_channel/PASESession.cpp
@@ -57,10 +57,15 @@ const char * kSpake2pContext        = "CHIP PAKE V1 Commissioning";
 const char * kSpake2pI2RSessionInfo = "Commissioning I2R Key";
 const char * kSpake2pR2ISessionInfo = "Commissioning R2I Key";
 
-// Wait at most 30 seconds for the response from the peer.
-// This timeout value assumes the underlying transport is reliable.
-// The session establishment fails if the response is not received with in timeout window.
-static constexpr ExchangeContext::Timeout kSpake2p_Response_Timeout = System::Clock::Seconds16(30);
+// Amounts of time to allow for server-side processing of messages.
+//
+// This timeout values only allow for the server-side processing and assume that any transport-specific
+// latency will be added to them.
+//
+// The session establishment fails if the response is not received within the resulting timeout window,
+//  which accounts for both transport latency and the server-side latency.
+static constexpr ExchangeContext::Timeout kExpectedLowProcessingTime  = System::Clock::Seconds16(2);
+static constexpr ExchangeContext::Timeout kExpectedHighProcessingTime = System::Clock::Seconds16(30);
 
 PASESession::~PASESession()
 {
@@ -216,7 +221,7 @@ CHIP_ERROR PASESession::Pair(SessionManager & sessionManager, uint32_t peerSetUp
     // When commissioning starts, the peer is assumed to be active.
     mExchangeCtxt->GetSessionHandle()->AsUnauthenticatedSession()->MarkActiveRx();
 
-    mExchangeCtxt->SetResponseTimeout(kSpake2p_Response_Timeout + mExchangeCtxt->GetSessionHandle()->GetAckTimeout());
+    mExchangeCtxt->UseSuggestedResponseTimeout(kExpectedLowProcessingTime);
 
     mLocalMRPConfig = mrpLocalConfig;
 
@@ -787,8 +792,8 @@ CHIP_ERROR PASESession::ValidateReceivedMessage(ExchangeContext * exchange, cons
     else
     {
         mExchangeCtxt = exchange;
-        mExchangeCtxt->SetResponseTimeout(kSpake2p_Response_Timeout + mExchangeCtxt->GetSessionHandle()->GetAckTimeout());
     }
+    mExchangeCtxt->UseSuggestedResponseTimeout(kExpectedHighProcessingTime);
 
     VerifyOrReturnError(!msg.IsNull(), CHIP_ERROR_INVALID_ARGUMENT);
     VerifyOrReturnError((mNextExpectedMsg.HasValue() && payloadHeader.HasMessageType(mNextExpectedMsg.Value())) ||