Add utility to get user default values for configurable parameters fo… (

project-chip#33056)

* Add utility to get user default values for configurable parameters for darwin

- Add support for getting a user default value for the SRP resolve timeout for DNS-SD. If user default
  value exists, ovveride the timeout.

- Update the SRP resolve timeout to 3 secs

The default can be set by using `defaults write org.csa-iot.matter.darwindefaults SRPTimeoutOverride <timeoutinMsecs>`

* Restyled by whitespace

* Restyled by clang-format

* Restyled by gn

* Address review comments

* Restyled by clang-format

* Add a check for filtering negative values and returning 0

* Apply suggestions from code review

Co-authored-by: Boris Zbarsky <[email protected]>

* Return an optional uint16_t value from GetUserDefaultDnssdSRPTimeoutInMSecs

* Restyled by clang-format

* Move the inclusion of optional header file in UserDefaults.h

* Include UserDefaults.h header in UserDefaults.mm file

* Include header cstdint from UserDefaults.h

---------

Co-authored-by: Restyled.io <[email protected]>
Co-authored-by: Boris Zbarsky <[email protected]>

src/platform/Darwin/BUILD.gn

@@ -76,6 +76,8 @@ static_library("Darwin") {
     "PosixConfig.h",
     "SystemPlatformConfig.h",
     "SystemTimeSupport.cpp",
+    "UserDefaults.h",
+    "UserDefaults.mm",
   ]
 
   if (chip_enable_wifi) {

src/platform/Darwin/DnssdImpl.cpp

@@ -17,6 +17,7 @@
 #include "DnssdImpl.h"
 #include "DnssdType.h"
 #include "MdnsError.h"
+#include "UserDefaults.h"
 
 #include <cstdio>
 
@@ -29,6 +30,7 @@
 
 using namespace chip::Dnssd;
 using namespace chip::Dnssd::Internal;
+using namespace chip::Platform;
 
 namespace {
 
@@ -76,8 +78,14 @@ void LogOnFailure(const char * name, DNSServiceErrorType err)
  */
 CHIP_ERROR StartSRPTimer(uint16_t timeoutInMSecs, ResolveContext * ctx)
 {
+    // Check to see if a user default value exists for the SRP timeout. If it does, override the timeoutInMSecs with user default
+    // value. To override the timeout value, use ` defaults write org.csa-iot.matter.darwin SRPTimeoutInMSecsOverride
+    // <timeoutinMsecs>` See UserDefaults.mm for details.
+    timeoutInMSecs = GetUserDefaultDnssdSRPTimeoutInMSecs().value_or(timeoutInMSecs);
+
     VerifyOrReturnValue(ctx != nullptr, CHIP_ERROR_INCORRECT_STATE);
-    ChipLogProgress(Discovery, "Starting timer to wait for possible SRP resolve results for %s", ctx->instanceName.c_str());
+    ChipLogProgress(Discovery, "Starting timer to wait for %d milliseconds for possible SRP resolve results for %s", timeoutInMSecs,
+                    ctx->instanceName.c_str());
     return chip::DeviceLayer::SystemLayer().StartTimer(chip::System::Clock::Milliseconds16(timeoutInMSecs),
                                                        ResolveContext::SRPTimerExpiredCallback, static_cast<void *>(ctx));
 }

src/platform/Darwin/DnssdImpl.h

@@ -262,8 +262,8 @@ struct ResolveContext : public GenericContext
     std::shared_ptr<uint32_t> consumerCounter;
     BrowseContext * const browseThatCausedResolve; // Can be null
 
-    // Indicates whether the timer for 250 msecs should be started
-    // to give the resolve on SRP domain some extra time to complete.
+    // Indicates whether the timer should be started to give the resolve
+    // on SRP domain some extra time to complete.
     bool shouldStartSRPTimerForResolve = false;
     bool isSRPTimerRunning             = false;
 

src/platform/Darwin/UserDefaults.h

@@ -0,0 +1,28 @@
+/*
+ *    Copyright (c) 2024 Project CHIP Authors
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#pragma once
+
+#include <cstdint>
+#include <optional>
+
+namespace chip {
+namespace Platform {
+
+std::optional<uint16_t> GetUserDefaultDnssdSRPTimeoutInMSecs();
+
+} // namespace Platform
+} // namespace chip

src/platform/Darwin/UserDefaults.mm

@@ -0,0 +1,43 @@
+/*
+ *
+ *    Copyright (c) 2024 Project CHIP Authors
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#include "UserDefaults.h"
+#include <lib/support/SafeInt.h>
+#include <lib/support/logging/CHIPLogging.h>
+
+#import <Foundation/Foundation.h>
+
+static NSString * const kUserDefaultDomain = @"org.csa-iot.matter.darwin";
+static NSString * const kSRPTimeoutInMsecsUserDefaultKey = @"SRPTimeoutInMSecsOverride";
+
+namespace chip {
+namespace Platform {
+
+    std::optional<uint16_t> GetUserDefaultDnssdSRPTimeoutInMSecs()
+    {
+        NSUserDefaults * defaults = [[NSUserDefaults alloc] initWithSuiteName:kUserDefaultDomain];
+        NSInteger srpTimeoutValue = [defaults integerForKey:kSRPTimeoutInMsecsUserDefaultKey];
+        if (CanCastTo<uint16_t>(srpTimeoutValue)) {
+            uint16_t timeoutinMsecs = static_cast<uint16_t>(srpTimeoutValue);
+            ChipLogProgress(Discovery, "Got a user default value for Dnssd SRP timeout - %d msecs", timeoutinMsecs);
+            return std::make_optional(timeoutinMsecs);
+        }
+        return std::nullopt;
+    }
+
+} // namespace Platform
+} // namespace chip