From fee31681c8042d2fbc5a65a3e4fc49d4763d6d9f Mon Sep 17 00:00:00 2001
From: Marcos <marcosh@duckduckgo.com>
Date: Fri, 17 Nov 2023 17:17:14 +0000
Subject: [PATCH] Use etld+1 to compare exceptions for the user agent (#3886)

Task/Issue URL:
https://app.asana.com/0/488551667048375/1205957264014376/f

### Description
Use etld+1 instead of sameorsubdomain for UA exceptions

### Steps to test this PR

- [ ] Test should pass
---
 .../java/com/duckduckgo/common/utils/UriString.kt | 12 ++++++++++++
 .../impl/features/useragent/RealUserAgent.kt      | 15 ++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/common/common-utils/src/main/java/com/duckduckgo/common/utils/UriString.kt b/common/common-utils/src/main/java/com/duckduckgo/common/utils/UriString.kt
index 2c167e491464..9a224570ec20 100644
--- a/common/common-utils/src/main/java/com/duckduckgo/common/utils/UriString.kt
+++ b/common/common-utils/src/main/java/com/duckduckgo/common/utils/UriString.kt
@@ -17,9 +17,11 @@
 package com.duckduckgo.common.utils
 
 import android.net.Uri
+import androidx.core.net.toUri
 import androidx.core.util.PatternsCompat
 import java.lang.IllegalArgumentException
 import okhttp3.HttpUrl.Companion.toHttpUrl
+import okhttp3.HttpUrl.Companion.toHttpUrlOrNull
 import timber.log.Timber
 
 class UriString {
@@ -35,6 +37,16 @@ class UriString {
             return Uri.parse(uriString).baseHost
         }
 
+        fun sameEffectiveTldPlusOne(child: String, parent: String): Boolean {
+            val childDomain = child.toUri().withScheme().toString().toHttpUrlOrNull() ?: return false
+            val parentDomain = parent.toUri().withScheme().toString().toHttpUrlOrNull() ?: return false
+
+            val childETldPlusOne = childDomain.topPrivateDomain()
+            val parentETldPlusOne = parentDomain.topPrivateDomain()
+
+            return childETldPlusOne == parentETldPlusOne
+        }
+
         fun sameOrSubdomain(
             child: String,
             parent: String,
diff --git a/privacy-config/privacy-config-impl/src/main/java/com/duckduckgo/privacy/config/impl/features/useragent/RealUserAgent.kt b/privacy-config/privacy-config-impl/src/main/java/com/duckduckgo/privacy/config/impl/features/useragent/RealUserAgent.kt
index 5be2390c01c9..16ae87632113 100644
--- a/privacy-config/privacy-config-impl/src/main/java/com/duckduckgo/privacy/config/impl/features/useragent/RealUserAgent.kt
+++ b/privacy-config/privacy-config-impl/src/main/java/com/duckduckgo/privacy/config/impl/features/useragent/RealUserAgent.kt
@@ -35,15 +35,20 @@ class RealUserAgent @Inject constructor(
 ) : UserAgent {
 
     override fun isAnApplicationException(url: String): Boolean {
-        return userAgentRepository.omitApplicationExceptions.any { UriString.sameOrSubdomain(url, it.domain) }
+        return userAgentRepository.omitApplicationExceptions.any { UriString.sameEffectiveTldPlusOne(url, it.domain) }
     }
 
     override fun isAVersionException(url: String): Boolean {
-        return userAgentRepository.omitVersionExceptions.any { UriString.sameOrSubdomain(url, it.domain) }
+        return userAgentRepository.omitVersionExceptions.any { UriString.sameEffectiveTldPlusOne(url, it.domain) }
     }
 
     override fun isADefaultException(url: String): Boolean {
-        return unprotectedTemporary.isAnException(url) || userAgentRepository.defaultExceptions.any { UriString.sameOrSubdomain(url, it.domain) }
+        return unprotectedTemporary.isAnException(url) || userAgentRepository.defaultExceptions.any {
+            UriString.sameEffectiveTldPlusOne(
+                url,
+                it.domain,
+            )
+        }
     }
 
     override fun defaultPolicy(): DefaultPolicy {
@@ -56,11 +61,11 @@ class RealUserAgent @Inject constructor(
     }
 
     override fun isADdgDefaultSite(url: String): Boolean {
-        return userAgentRepository.ddgDefaultSites.any { UriString.sameOrSubdomain(url, it.domain) }
+        return userAgentRepository.ddgDefaultSites.any { UriString.sameEffectiveTldPlusOne(url, it.domain) }
     }
 
     override fun isADdgFixedSite(url: String): Boolean {
-        return userAgentRepository.ddgFixedSites.any { UriString.sameOrSubdomain(url, it.domain) }
+        return userAgentRepository.ddgFixedSites.any { UriString.sameEffectiveTldPlusOne(url, it.domain) }
     }
 
     override fun closestUserAgentEnabled(): Boolean {