New SSL metric added: Likely From Same Domain

chrome/browser/ssl/ssl_error_classification.cc

Index: chrome/browser/ssl/ssl_error_classification.cc
diff --git a/chrome/browser/ssl/ssl_error_classification.cc b/chrome/browser/ssl/ssl_error_classification.cc
index eea89250afa724677523c9a09e001a80b2e5b6ae..c7ac505bd90e0507f2357e096eaafb2b78121a87 100644
--- a/chrome/browser/ssl/ssl_error_classification.cc
+++ b/chrome/browser/ssl/ssl_error_classification.cc
@@ -55,6 +55,7 @@ enum SSLInterstitialCause {
   AUTHORITY_ERROR_CAPTIVE_PORTAL,
   SELF_SIGNED,
   EXPIRED_RECENTLY,
+  LIKELY_SAME_DOMAIN,
   UNUSED_INTERSTITIAL_CAUSE_ENTRY,
 };
 
@@ -208,6 +209,8 @@ void SSLErrorClassification::RecordUMAStatistics(
           RecordSSLInterstitialCause(overridable, SUBDOMAIN_INVERSE_MATCH);
         if (IsCertLikelyFromMultiTenantHosting())
           RecordSSLInterstitialCause(overridable, LIKELY_MULTI_TENANT_HOSTING);
+        if (IsCertLikelyFromSameDomain())
+          RecordSSLInterstitialCause(overridable, LIKELY_SAME_DOMAIN);
       } else {
          RecordSSLInterstitialCause(overridable, HOST_NAME_NOT_KNOWN_TLD);
       }
@@ -463,6 +466,29 @@ bool SSLErrorClassification::IsCertLikelyFromMultiTenantHosting() const {
   return true;
 }
 
+bool SSLErrorClassification::IsCertLikelyFromSameDomain() const {
+  std::string host_name = request_url_.host();
+  std::vector<std::string> dns_names;
+  cert_.GetDNSNames(&dns_names);
+
+  dns_names.push_back(host_name);
+  std::vector<std::string> dns_names_domain;
+
+  for (const std::string& dns_name : dns_names) {
+    dns_names_domain.push_back(
+        net::registry_controlled_domains::GetDomainAndRegistry(
+            dns_name,
+            net::registry_controlled_domains::INCLUDE_PRIVATE_REGISTRIES));
+  }
+
+  DCHECK(!dns_names_domain.empty());
+  const std::string& host_name_domain = dns_names_domain.back();
+
+  // Last element is the original domain. So, excluding it.
+  return std::find(dns_names_domain.begin(), dns_names_domain.end() - 1,
+                   host_name_domain) != dns_names_domain.end() - 1;
+}
+
 // static
 bool SSLErrorClassification::IsHostnameNonUniqueOrDotless(
     const std::string& hostname) {