Merge "Add experiment flag for DNS query global limiter" (7299cab9) · Commits · e / os / android_packages_modules_DnsResolver

Experiments.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -68,6 +68,7 @@ class Experiments {
		"doh_idle_timeout_ms",
		"doh_session_resumption",
		"mdns_resolution",
		"max_queries_global",
		};
		// This value is used in updateInternal as the default value if any flags can't be found.
		static constexpr int kFlagIntDefault = INT_MIN;

OperationLimiter.h

+12 −7

Original line number	Diff line number	Diff line
		@@ -23,6 +23,8 @@
		#include <android-base/logging.h>
		#include <android-base/thread_annotations.h>

		#include "Experiments.h"

		namespace android {
		namespace netdutils {

		@@ -43,8 +45,7 @@ namespace netdutils {
		template <typename KeyType>
		class OperationLimiter {
		public:
		OperationLimiter(int limitPerKey, int globalLimit = INT_MAX)
		: mLimitPerKey(limitPerKey), mGlobalLimit(globalLimit) {}
		OperationLimiter(int limitPerKey) : mLimitPerKey(limitPerKey) {}

		~OperationLimiter() {
		DCHECK(mCounters.empty()) << "Destroying OperationLimiter with active operations";
		@@ -57,15 +58,22 @@ class OperationLimiter {
		// finish(key).
		bool start(KeyType key) EXCLUDES(mMutex) {
		std::lock_guard lock(mMutex);

		if (mGlobalCounter >= mGlobalLimit) {
		int globalLimit =
		android::net::Experiments::getInstance()->getFlag("max_queries_global", INT_MAX);
		if (globalLimit < mLimitPerKey) {
		LOG(ERROR) << "Misconfiguration on max_queries_global " << globalLimit;
		globalLimit = INT_MAX;
		}
		if (mGlobalCounter >= globalLimit) {
		// Oh, no!
		LOG(ERROR) << "Query from " << key << " denied due to global limit: " << globalLimit;
		return false;
		}

		auto& cnt = mCounters[key]; // operator[] creates new entries as needed.
		if (cnt >= mLimitPerKey) {
		// Oh, no!
		LOG(ERROR) << "Query from " << key << " denied due to limit: " << mLimitPerKey;
		return false;
		}

		@@ -109,9 +117,6 @@ class OperationLimiter {

		// Maximum number of outstanding queries from a single key.
		const int mLimitPerKey;

		// Maximum number of outstanding queries, globally.
		const int mGlobalLimit;
		};

		} // namespace netdutils