From 9fe2d69cf19655a8cc793d2a610eb8d62ef0c5ed Mon Sep 17 00:00:00 2001
From: bgrozev <boris@jitsi.org>
Date: Wed, 23 Aug 2023 16:38:31 -0500
Subject: [PATCH] Randomize consent check interval (follow rfc7675). (#270)

* Randomize consent check interval (follow rfc7675).
---
 src/main/java/org/ice4j/ice/Agent.java       | 14 +++++++++++++-
 src/main/kotlin/org/ice4j/ice/AgentConfig.kt |  4 ++++
 src/main/resources/reference.conf            |  3 +++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/ice4j/ice/Agent.java b/src/main/java/org/ice4j/ice/Agent.java
index a9e68764..19738057 100644
--- a/src/main/java/org/ice4j/ice/Agent.java
+++ b/src/main/java/org/ice4j/ice/Agent.java
@@ -2656,7 +2656,19 @@ protected Duration getDelayUntilNextRun()
         {
             if (shouldRunStunKeepAlive())
             {
-                return Duration.ofMillis(keepAliveSent == 0 ? 0 : consentFreshnessInterval);
+                if (keepAliveSent == 0)
+                {
+                    return Duration.ZERO;
+                }
+                else
+                {
+                    double r = 1;
+                    if (config.getRandomizeConsentFreshnessInterval())
+                    {
+                        r = 0.8d + ThreadLocalRandom.current().nextDouble() * 0.4;
+                    }
+                    return Duration.ofMillis((long) (consentFreshnessInterval * r));
+                }
             }
             return Duration.ofMillis(-1);
         }
diff --git a/src/main/kotlin/org/ice4j/ice/AgentConfig.kt b/src/main/kotlin/org/ice4j/ice/AgentConfig.kt
index d436fe34..5eeb05d2 100644
--- a/src/main/kotlin/org/ice4j/ice/AgentConfig.kt
+++ b/src/main/kotlin/org/ice4j/ice/AgentConfig.kt
@@ -27,6 +27,10 @@ class AgentConfig {
         "ice4j.consent-freshness.interval".from(configSource)
     }
 
+    val randomizeConsentFreshnessInterval: Boolean by config {
+        "ice4j.consent-freshness.randomize".from(configSource)
+    }
+
     val consentFreshnessOriginalWaitInterval: Duration by config {
         "org.ice4j.ice.CONSENT_FRESHNESS_WAIT_INTERVAL".from(configSource)
             .convertFrom<Long> { Duration.ofMillis(it) }
diff --git a/src/main/resources/reference.conf b/src/main/resources/reference.conf
index c572849a..a55a5549 100644
--- a/src/main/resources/reference.conf
+++ b/src/main/resources/reference.conf
@@ -31,6 +31,9 @@ ice4j {
     // The maximum number of retransmissions of a STUN Binding request without a valid STUN Binding response after which
     // consent freshness is to be considered unconfirmed according to `STUN Usage for Consent Freshness` (RFC7675).
     max-retransmissions = 30
+    // Whether to randomize the period between any two checks between 0.8 and 1.2 of the configured interval as
+    // recommended in RFC7675 Section 5.1. We keep this configurable in case the previous behavior is desired.
+    randomize-interval = true
   }
 
   // Configuration related to harvesting (aka gathering) of local candidates.