[DRUEL04] Implement unsolicited NAT64 prefix event

Implement unsolicited NAT64 prefix event that will report to the
listener when change NAT64 prefix.

Bug: 173485754
Test: atest resolv_integration_test resolv_unit_test\
      resolv_stress_test resolv_stats_test_utils_test
Change-Id: If20353529969ffa956b56d19345519f286046e25

2 files changed, 51 insertions, 2 deletions

diff --git a/tests/unsolicited_listener/unsolicited_event_listener.cpp b/tests/unsolicited_listener/unsolicited_event_listener.cpp
index f5ebb0b4..8cf75054 100644
--- a/tests/unsolicited_listener/unsolicited_event_listener.cpp
+++ b/tests/unsolicited_listener/unsolicited_event_listener.cpp
@@ -23,11 +23,14 @@
 
 namespace android::net::resolv::aidl {
 
+using ::aidl::android::net::resolv::aidl::IDnsResolverUnsolicitedEventListener;
+using ::aidl::android::net::resolv::aidl::Nat64PrefixEventParcel;
 using ::aidl::android::net::resolv::aidl::PrivateDnsValidationEventParcel;
 using android::base::ScopedLockAssertion;
 using std::chrono::milliseconds;
 
 constexpr milliseconds kEventTimeoutMs{5000};
+constexpr milliseconds kRetryIntervalMs{20};
 
 ::ndk::ScopedAStatus UnsolicitedEventListener::onDnsHealthEvent(
         const ::aidl::android::net::resolv::aidl::DnsHealthEventParcel&) {
@@ -36,8 +39,15 @@ constexpr milliseconds kEventTimeoutMs{5000};
 }
 
 ::ndk::ScopedAStatus UnsolicitedEventListener::onNat64PrefixEvent(
-        const ::aidl::android::net::resolv::aidl::Nat64PrefixEventParcel&) {
-    // default no-op
+        const Nat64PrefixEventParcel& event) {
+    std::lock_guard lock(mMutex);
+    mUnexpectedNat64PrefixUpdates++;
+    if (event.netId == mNetId) {
+        mNat64PrefixAddress = (event.prefixOperation ==
+                               IDnsResolverUnsolicitedEventListener::PREFIX_OPERATION_ADDED)
+                                      ? event.prefixAddress
+                                      : "";
+    }
     return ::ndk::ScopedAStatus::ok();
 }
 
@@ -77,4 +87,22 @@ bool UnsolicitedEventListener::findAndRemoveValidationRecord(const ServerKey& ke
     return false;
 }
 
+bool UnsolicitedEventListener::waitForNat64Prefix(int operation, const milliseconds& timeout) {
+    android::base::Timer t;
+    while (t.duration() < timeout) {
+        {
+            std::lock_guard lock(mMutex);
+            if ((operation == IDnsResolverUnsolicitedEventListener::PREFIX_OPERATION_ADDED &&
+                 !mNat64PrefixAddress.empty()) ||
+                (operation == IDnsResolverUnsolicitedEventListener::PREFIX_OPERATION_REMOVED &&
+                 mNat64PrefixAddress.empty())) {
+                mUnexpectedNat64PrefixUpdates--;
+                return true;
+            }
+        }
+        std::this_thread::sleep_for(kRetryIntervalMs);
+    }
+    return false;
+}
+
 }  // namespace android::net::resolv::aidl
diff --git a/tests/unsolicited_listener/unsolicited_event_listener.h b/tests/unsolicited_listener/unsolicited_event_listener.h
index 5615f241..e8fce1de 100644
--- a/tests/unsolicited_listener/unsolicited_event_listener.h
+++ b/tests/unsolicited_listener/unsolicited_event_listener.h
@@ -44,15 +44,26 @@ class UnsolicitedEventListener
     // Wait for the expected private DNS validation result until timeout.
     bool waitForPrivateDnsValidation(const std::string& serverAddr, int validation);
 
+    // Wait for expected NAT64 prefix operation until timeout.
+    bool waitForNat64Prefix(int operation, const std::chrono::milliseconds& timeout)
+            EXCLUDES(mMutex);
+
     // Return true if a validation result for |serverAddr| is found; otherwise, return false.
     bool findValidationRecord(const std::string& serverAddr) const EXCLUDES(mMutex) {
         std::lock_guard lock(mMutex);
         return mValidationRecords.find({mNetId, serverAddr}) != mValidationRecords.end();
     }
 
+    // Returns the number of updates to the NAT64 prefix that have not yet been waited for.
+    int getUnexpectedNat64PrefixUpdates() const EXCLUDES(mMutex) {
+        std::lock_guard lock(mMutex);
+        return mUnexpectedNat64PrefixUpdates;
+    }
+
     void reset() EXCLUDES(mMutex) {
         std::lock_guard lock(mMutex);
         mValidationRecords.clear();
+        mUnexpectedNat64PrefixUpdates = 0;
     }
 
   private:
@@ -68,6 +79,16 @@ class UnsolicitedEventListener
     // Used to store the data from onPrivateDnsValidationEvent.
     std::map<ServerKey, int> mValidationRecords GUARDED_BY(mMutex);
 
+    // The NAT64 prefix address of the network |mNetId|. It is updated by onNat64PrefixEvent().
+    std::string mNat64PrefixAddress GUARDED_BY(mMutex);
+
+    // The number of updates to the NAT64 prefix of network |mNetId| that have not yet been waited
+    // for. Increases by 1 every time onNat64PrefixEvent is called, and decreases by 1 every time
+    // waitForNat64Prefix returns true.
+    // This allows tests to check that no unexpected events have been received without having to
+    // resort to timeouts that make the tests slower and flakier.
+    int mUnexpectedNat64PrefixUpdates GUARDED_BY(mMutex);
+
     mutable std::mutex mMutex;
     std::condition_variable mCv;
 };