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>`

Author: nivi-apple

src/platform/Darwin/BUILD.gn

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

src/platform/Darwin/DnssdImpl.cpp

@@ -17,6 +17,7 @@
 #include "DnssdImpl.h"
 #include "DnssdType.h"
 #include "MdnsError.h"
+#include "UserDefaultUtils.h"
 
 #include <cstdio>
 
@@ -29,6 +30,7 @@
 
 using namespace chip::Dnssd;
 using namespace chip::Dnssd::Internal;
+using namespace chip::DeviceLayer::Utils;
 
 namespace {
 
@@ -37,7 +39,7 @@ constexpr char kLocalDot[] = "local.";
 constexpr char kSRPDot[] = "default.service.arpa.";
 
 // The extra time in milliseconds that we will wait for the resolution on the SRP domain to complete.
-constexpr uint16_t kSRPTimeoutInMsec = 250;
+constexpr uint16_t kSRPTimeoutInMsec = 3000;
 
 constexpr DNSServiceFlags kRegisterFlags        = kDNSServiceFlagsNoAutoRename;
 constexpr DNSServiceFlags kBrowseFlags          = kDNSServiceFlagsShareConnection;
@@ -76,8 +78,16 @@ void LogOnFailure(const char * name, DNSServiceErrorType err)
  */
 CHIP_ERROR StartSRPTimer(uint16_t timeoutInMSecs, ResolveContext * ctx)
 {
+    // Check to see if an 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.darwindefaults SRPTimeoutOverride <timeoutinMsecs>`
+    // See UserDefaultUtils.mm for details
+    uint16_t userDefaultSRPTimeout = getUserDefaultDnssdSRPTimeout();
+    if (userDefaultSRPTimeout)
+    {
+        timeoutInMSecs = userDefaultSRPTimeout;
+    }
     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/UserDefaultUtils.h

@@ -0,0 +1,27 @@
+/*
+ *
+ *    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.
+ */
+
+namespace chip {
+namespace DeviceLayer {
+namespace Utils {
+
+uint16_t getUserDefaultDnssdSRPTimeout();
+
+} // namespace Utils
+} // namespace DeviceLayer
+} // namespace chip
+

src/platform/Darwin/UserDefaultUtils.mm

@@ -0,0 +1,41 @@
+/*
+ *
+ *    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.
+ */
+
+/**
+ *    @file
+ *          Implementation for an utility to set configurable parametes via user defaults.
+ */
+#import <Foundation/Foundation.h>
+#import "UserDefaultUtils.h"
+
+
+static NSString * const kUserDefaultDomain = @"org.csa-iot.matter.darwindefaults";
+static NSString * const kSRPTimeoutUserDefaultKey = @"SRPTimeoutOverride";
+
+namespace chip {
+namespace DeviceLayer {
+namespace Utils {
+
+uint16_t getUserDefaultDnssdSRPTimeout()
+{
+    NSUserDefaults * defaults = [[NSUserDefaults alloc] initWithSuiteName:kUserDefaultDomain];
+    return static_cast<uint16_t>([defaults integerForKey:kSRPTimeoutUserDefaultKey]);
+}
+
+} // namespace Utils
+} // namespace DeviceLayer
+} // namespace chip