Improve Exit Error Handling for failures in PASE pairing requests (#3…

…6160)

* Improve Error Handling for failures in PASE pairing requests

* Integrating comments

* clarifying Pair API contract regarding the delegate

* integrating comment on API

src/protocols/secure_channel/PASESession.cpp

@@ -232,7 +232,15 @@ CHIP_ERROR PASESession::Pair(SessionManager & sessionManager, uint32_t peerSetUp
 exit:
  if (err != CHIP_NO_ERROR)
  {
+ // If a failure happens before we have placed the incoming exchange into `mExchangeCtxt`, we need to make
+ // sure to close the exchange to fulfill our API contract.
+ if (!mExchangeCtxt.HasValue())
+ {
+ exchangeCtxt->Close();
+ }
  Clear();
+ ChipLogError(SecureChannel, "Failed during PASE session pairing request: %" CHIP_ERROR_FORMAT, err.Format());
+ MATTER_TRACE_COUNTER("PASEFail");
  }
  return err;
 }

src/protocols/secure_channel/PASESession.h

@@ -99,6 +99,8 @@ class DLL_EXPORT PASESession : public Messaging::UnsolicitedMessageHandler,
  * ownership of the exchangeCtxt to PASESession object. PASESession
  * will close the exchange on (successful/failed) handshake completion.
  * @param delegate Callback object
+ * The delegate will be notified if and only if Pair() returns success. Errors occurring after Pair()
+ * returns success will be reported via the delegate.
  *
  * @return CHIP_ERROR The result of initialization
  */