[Simplified domains] Add finch param for excluding keyword matches in e2LD.

This CL is a small tweak to allow us to tune whether or not the keyword
matching heuristic applies to the e2LD or not. To maintain current
behavior, the default value of the parameter is kept to true.

Fixed: 1123151
Change-Id: Ifc85b464776e874a24fe4ec69be6c2aae0960eda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2382404
Commit-Queue: Joe DeBlasio <jdeblasio@chromium.org>
Reviewed-by: Emily Stark <estark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802886}

chrome/browser/reputation/local_heuristics.cc

@@ -111,13 +111,15 @@ bool ShouldTriggerSafetyTipFromKeywordInURL(
     const char* const sensitive_keywords[],
     const size_t num_sensitive_keywords) {
   return HostnameContainsKeyword(url, navigated_domain.domain_and_registry,
-                                 sensitive_keywords, num_sensitive_keywords);
+                                 sensitive_keywords, num_sensitive_keywords,
+                                 /* search_e2ld = */ true);
 }
 
 bool HostnameContainsKeyword(const GURL& url,
                              const std::string& eTLD_plus_one,
                              const char* const keywords[],
-                             const size_t num_keywords) {
+                             const size_t num_keywords,
+                             bool search_e2ld) {
   // We never want to trigger this heuristic on any non-http / https sites.
   if (!url.SchemeIsHTTPOrHTTPS()) {
     return false;
@@ -150,10 +152,10 @@ bool HostnameContainsKeyword(const GURL& url,
   // Any problems that would result in an empty e2LD should have been caught via
   // the |eTLD_plus_one| check.
 
-  // If the e2LD is itself a keyword, then chop that off and only
-  // search the rest of it. Otherwise, we keep the full e2LD included to
-  // detect hyphenated spoofs (e.g. "evil-google.com").
-  if (SortedWordListContains(e2LD, keywords, num_keywords)) {
+  // If we want to exclude the e2LD, or if the e2LD is itself a keyword, then
+  // chop that off and only search the rest of it. Otherwise, we keep the full
+  // e2LD included to detect hyphenated spoofs (e.g. "evil-google.com").
+  if (!search_e2ld || SortedWordListContains(e2LD, keywords, num_keywords)) {
     // If the user visited the eTLD+1 directly, bail here.
     if (search_substr.size() == e2LD.size()) {
       return false;

chrome/browser/reputation/local_heuristics.h

@@ -39,10 +39,14 @@ bool ShouldTriggerSafetyTipFromKeywordInURL(
 // Checks to see whether a hostname contains sensitive keywords in a way
 // that violates our hostname elision policy.
 //
+// If |search_e2ld| is false, only finds keywords in subdomains below the e2LD
+// (e.g. it will only search through "foo.bar" in "foo.bar.example.com").
+//
 // Returns false when called with a URL without a TLD or with an unknown TLD.
 bool HostnameContainsKeyword(const GURL& url,
                              const std::string& eTLD_plus_one,
                              const char* const sensitive_keywords[],
-                             const size_t num_sensitive_keywords);
+                             const size_t num_sensitive_keywords,
+                             bool search_e2ld);
 
 #endif  // CHROME_BROWSER_REPUTATION_LOCAL_HEURISTICS_H_

chrome/browser/reputation/url_elision_policy.cc

@@ -20,6 +20,8 @@ const base::FeatureParam<int> kMaximumUnelidedHostnameLength{
     &omnibox::kMaybeElideToRegistrableDomain, "max_unelided_host_length", 25};
 const base::FeatureParam<bool> kEnableKeywordBasedElision{
     &omnibox::kMaybeElideToRegistrableDomain, "enable_keyword_elision", true};
+const base::FeatureParam<bool> kSearchE2LDForKeywords{
+    &omnibox::kMaybeElideToRegistrableDomain, "search_e2ld_for_keywords", true};
 
 }  // namespace
 
@@ -46,7 +48,8 @@ bool ShouldElideToRegistrableDomain(const GURL& url) {
   auto eTLD_plus_one = GetETLDPlusOne(host);
   if (kEnableKeywordBasedElision.Get() &&
       HostnameContainsKeyword(url, eTLD_plus_one, top500_domains::kTopKeywords,
-                              top500_domains::kNumTopKeywords)) {
+                              top500_domains::kNumTopKeywords,
+                              kSearchE2LDForKeywords.Get())) {
     return true;
   }
 

chrome/browser/reputation/url_elision_policy_unittest.cc

@@ -21,6 +21,12 @@ namespace {
 // hostnames that are reliably shorter/longer than the limit.
 const char* kMaxUnelidedHostLengthParam = "20";
 
+enum class KeywordSearchConfig {
+  kDisabled,
+  kEnabledWithE2LD,
+  kEnabledWithoutE2LD
+};
+
 }  // namespace
 
 class UrlElisionPolicyTest : public testing::Test {
@@ -105,27 +111,43 @@ TEST_F(UrlElisionPolicyTest, ElidesKeywordedDomainsAppropriately) {
       ShouldElideToRegistrableDomain(GURL("ftp://google.login.com/xyz")));
 }
 
-class UrlElisionKeywordPolicyTest : public UrlElisionPolicyTest,
-                                    public testing::WithParamInterface<bool> {
+class UrlElisionKeywordPolicyTest
+    : public UrlElisionPolicyTest,
+      public testing::WithParamInterface<KeywordSearchConfig> {
  public:
   UrlElisionKeywordPolicyTest() {
-    if (!GetParam()) {
-      scoped_feature_list_.InitWithFeaturesAndParameters(
-          {{omnibox::kMaybeElideToRegistrableDomain,
-            {{"max_unelided_host_length", kMaxUnelidedHostLengthParam}}}},
-          {});
-    } else {
-      scoped_feature_list_.InitWithFeaturesAndParameters(
-          {{omnibox::kMaybeElideToRegistrableDomain,
-            {{"max_unelided_host_length", kMaxUnelidedHostLengthParam},
-             {"enable_keyword_elision", "false"}}}},
-          {});
+    switch (GetParam()) {
+      case KeywordSearchConfig::kDisabled:
+        scoped_feature_list_.InitWithFeaturesAndParameters(
+            {{omnibox::kMaybeElideToRegistrableDomain,
+              {{"max_unelided_host_length", kMaxUnelidedHostLengthParam},
+               {"enable_keyword_elision", "false"}}}},
+            {});
+        break;
+      case KeywordSearchConfig::kEnabledWithE2LD:
+        scoped_feature_list_.InitWithFeaturesAndParameters(
+            {{omnibox::kMaybeElideToRegistrableDomain,
+              {{"max_unelided_host_length", kMaxUnelidedHostLengthParam},
+               {"enable_keyword_elision", "true"},
+               {"search_e2ld_for_keywords", "true"}}}},
+            {});
+        break;
+      case KeywordSearchConfig::kEnabledWithoutE2LD:
+        scoped_feature_list_.InitWithFeaturesAndParameters(
+            {{omnibox::kMaybeElideToRegistrableDomain,
+              {{"max_unelided_host_length", kMaxUnelidedHostLengthParam},
+               {"enable_keyword_elision", "true"},
+               {"search_e2ld_for_keywords", "false"}}}},
+            {});
+        break;
     }
   }
 
   ~UrlElisionKeywordPolicyTest() override = default;
 
-  bool IsKeywordElisionEnabled() { return !GetParam(); }
+  bool IsKeywordElisionEnabled() {
+    return GetParam() != KeywordSearchConfig::kDisabled;
+  }
 
  private:
   base::test::ScopedFeatureList scoped_feature_list_;
@@ -133,10 +155,21 @@ class UrlElisionKeywordPolicyTest : public UrlElisionPolicyTest,
   DISALLOW_COPY_AND_ASSIGN(UrlElisionKeywordPolicyTest);
 };
 
-INSTANTIATE_TEST_SUITE_P(All, UrlElisionKeywordPolicyTest, testing::Bool());
+INSTANTIATE_TEST_SUITE_P(
+    All,
+    UrlElisionKeywordPolicyTest,
+    ::testing::Values(KeywordSearchConfig::kDisabled,
+                      KeywordSearchConfig::kEnabledWithE2LD,
+                      KeywordSearchConfig::kEnabledWithoutE2LD));
 
 // Verify that keyword elision follows the feature parameter.
 TEST_P(UrlElisionKeywordPolicyTest, ElidesOnKeywords) {
   EXPECT_EQ(IsKeywordElisionEnabled(),
+            ShouldElideToRegistrableDomain(GURL("http://google.evil.com/xyz")));
+}
+
+// Verify that keyword elision respects the e2LD inclusion parameter.
+TEST_P(UrlElisionKeywordPolicyTest, RespectsE2LDParam) {
+  EXPECT_EQ(GetParam() == KeywordSearchConfig::kEnabledWithE2LD,
             ShouldElideToRegistrableDomain(GURL("http://google-evil.com/xyz")));
 }