Bug 1342258 - Refactor SetDomain to IsRegistrableDomainSuffixOfOrEqua…

…lTo r=smaug

This commit refactors the SetDomain method in a Document to call a new function
IsRegistrableDomainSuffixOfOrEqualTo(), defined in HTML [1]. This commit tries
not to rename anything except input variables, so as to remain as clear as
possible. It likely should have various variables renamed, but given the
author's unfamiliarity with this module, review seems a good time to do that.
It's also duplicating comments a little bit; let me know which one(s) you'd like
to keep!

Note: Commentary on the HTML change is available in the PR [2], and the
rationale for this behavior in Web Auentication, where this algorithm will be
used, is also recorded [3].

Update 1: Refactored two new protected methods to avoid code duplication.
Update 2: Bugfix: Be sure to use CreateInheritingURIForHost for the
provided domain so as to catch internationalized domains.
Update 3: Nit-fix and rebase

[1] https://html.spec.whatwg.org/multipage/browsers.html#is-a-registrable-domain-suffix-of-or-is-equal-to
[2] whatwg/html#2365
[3] w3ctag/design-reviews#97 (comment)

MozReview-Commit-ID: 4Dr8yOMdhez

--HG--
extra : rebase_source : 634bd3c7b60c7ad996ee38ab7314071b426e3f6f

dom/html/nsHTMLDocument.cpp

@@ -906,64 +906,64 @@ nsHTMLDocument::GetDomain(nsAString& aDomain)
   return NS_OK;
 }
 
-NS_IMETHODIMP
-nsHTMLDocument::SetDomain(const nsAString& aDomain)
-{
-  ErrorResult rv;
-  SetDomain(aDomain, rv);
-  return rv.StealNSResult();
-}
-
-void
-nsHTMLDocument::SetDomain(const nsAString& aDomain, ErrorResult& rv)
+already_AddRefed<nsIURI>
+nsHTMLDocument::CreateInheritingURIForHost(const nsACString& aHostString)
 {
-  if (mSandboxFlags & SANDBOXED_DOMAIN) {
-    // We're sandboxed; disallow setting domain
-    rv.Throw(NS_ERROR_DOM_SECURITY_ERR);
-    return;
-  }
-
-  if (aDomain.IsEmpty()) {
-    rv.Throw(NS_ERROR_DOM_BAD_DOCUMENT_DOMAIN);
-    return;
+  if (aHostString.IsEmpty()) {
+    return nullptr;
   }
 
   // Create new URI
   nsCOMPtr<nsIURI> uri = GetDomainURI();
-
   if (!uri) {
-    rv.Throw(NS_ERROR_FAILURE);
-    return;
+    return nullptr;
   }
 
   nsCOMPtr<nsIURI> newURI;
-  nsresult rv2 = uri->Clone(getter_AddRefs(newURI));
-  if (NS_FAILED(rv2)) {
-    rv.Throw(rv2);
-    return;
+  nsresult rv = uri->Clone(getter_AddRefs(newURI));
+  if (NS_FAILED(rv)) {
+    return nullptr;
   }
 
-  rv2 = newURI->SetUserPass(EmptyCString());
-  if (NS_FAILED(rv2)) {
-    rv.Throw(rv2);
-    return;
+  rv = newURI->SetUserPass(EmptyCString());
+  if (NS_FAILED(rv)) {
+    return nullptr;
   }
 
   // We use SetHostAndPort because we want to reset the port number if needed.
-  rv2 = newURI->SetHostAndPort(NS_ConvertUTF16toUTF8(aDomain));
-  if (NS_FAILED(rv2)) {
-    rv.Throw(rv2);
-    return;
+  rv = newURI->SetHostAndPort(aHostString);
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  return newURI.forget();
+}
+
+already_AddRefed<nsIURI>
+nsHTMLDocument::RegistrableDomainSuffixOfInternal(const nsAString& aNewDomain,
+                                                  nsIURI* aOrigHost)
+{
+  if (NS_WARN_IF(!aOrigHost)) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIURI> newURI = CreateInheritingURIForHost(NS_ConvertUTF16toUTF8(aNewDomain));
+  if (!newURI) {
+    // Error: failed to parse input domain
+    return nullptr;
   }
 
   // Check new domain - must be a superdomain of the current host
   // For example, a page from foo.bar.com may set domain to bar.com,
   // but not to ar.com, baz.com, or fi.foo.bar.com.
-  nsAutoCString current, domain;
-  if (NS_FAILED(uri->GetAsciiHost(current)))
+  nsAutoCString current;
+  nsAutoCString domain;
+  if (NS_FAILED(aOrigHost->GetAsciiHost(current))) {
     current.Truncate();
-  if (NS_FAILED(newURI->GetAsciiHost(domain)))
+  }
+  if (NS_FAILED(newURI->GetAsciiHost(domain))) {
     domain.Truncate();
+  }
 
   bool ok = current.Equals(domain);
   if (current.Length() > domain.Length() &&
@@ -974,18 +974,83 @@ nsHTMLDocument::SetDomain(const nsAString& aDomain, ErrorResult& rv)
     nsCOMPtr<nsIEffectiveTLDService> tldService =
       do_GetService(NS_EFFECTIVETLDSERVICE_CONTRACTID);
     if (!tldService) {
-      rv.Throw(NS_ERROR_NOT_AVAILABLE);
-      return;
+      return nullptr;
     }
 
     nsAutoCString currentBaseDomain;
-    ok = NS_SUCCEEDED(tldService->GetBaseDomain(uri, 0, currentBaseDomain));
+    ok = NS_SUCCEEDED(tldService->GetBaseDomain(aOrigHost, 0, currentBaseDomain));
     NS_ASSERTION(StringEndsWith(domain, currentBaseDomain) ==
                  (domain.Length() >= currentBaseDomain.Length()),
                  "uh-oh!  slight optimization wasn't valid somehow!");
     ok = ok && domain.Length() >= currentBaseDomain.Length();
   }
+
   if (!ok) {
+    // Error: illegal domain
+    return nullptr;
+  }
+
+  return CreateInheritingURIForHost(domain);
+}
+
+bool
+nsHTMLDocument::IsRegistrableDomainSuffixOfOrEqualTo(const nsAString& aHostSuffixString,
+                                                     const nsACString& aOrigHost)
+{
+  // https://html.spec.whatwg.org/multipage/browsers.html#is-a-registrable-domain-suffix-of-or-is-equal-to
+  if (aHostSuffixString.IsEmpty()) {
+    return false;
+  }
+
+  nsCOMPtr<nsIURI> origURI = CreateInheritingURIForHost(aOrigHost);
+  if (!origURI) {
+    // Error: failed to parse input domain
+    return false;
+  }
+
+  nsCOMPtr<nsIURI> newURI = RegistrableDomainSuffixOfInternal(aHostSuffixString, origURI);
+  if (!newURI) {
+    // Error: illegal domain
+    return false;
+  }
+  return true;
+}
+
+
+NS_IMETHODIMP
+nsHTMLDocument::SetDomain(const nsAString& aDomain)
+{
+  ErrorResult rv;
+  SetDomain(aDomain, rv);
+  return rv.StealNSResult();
+}
+
+void
+nsHTMLDocument::SetDomain(const nsAString& aDomain, ErrorResult& rv)
+{
+  if (mSandboxFlags & SANDBOXED_DOMAIN) {
+    // We're sandboxed; disallow setting domain
+    rv.Throw(NS_ERROR_DOM_SECURITY_ERR);
+    return;
+  }
+
+  if (aDomain.IsEmpty()) {
+    rv.Throw(NS_ERROR_DOM_BAD_DOCUMENT_DOMAIN);
+    return;
+  }
+
+  nsCOMPtr<nsIURI> uri = GetDomainURI();
+  if (!uri) {
+    rv.Throw(NS_ERROR_FAILURE);
+    return;
+  }
+
+  // Check new domain - must be a superdomain of the current host
+  // For example, a page from foo.bar.com may set domain to bar.com,
+  // but not to ar.com, baz.com, or fi.foo.bar.com.
+
+  nsCOMPtr<nsIURI> newURI = RegistrableDomainSuffixOfInternal(aDomain, uri);
+  if (!newURI) {
     // Error: illegal domain
     rv.Throw(NS_ERROR_DOM_BAD_DOCUMENT_DOMAIN);
     return;

dom/html/nsHTMLDocument.h

@@ -166,6 +166,8 @@ class nsHTMLDocument : public nsDocument,
   virtual JSObject* WrapNode(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
     override;
   void SetDomain(const nsAString& aDomain, mozilla::ErrorResult& rv);
+  bool IsRegistrableDomainSuffixOfOrEqualTo(const nsAString& aHostSuffixString,
+                                            const nsACString& aOrigHost);
   void GetCookie(nsAString& aCookie, mozilla::ErrorResult& rv);
   void SetCookie(const nsAString& aCookie, mozilla::ErrorResult& rv);
   void NamedGetter(JSContext* cx, const nsAString& aName, bool& aFound,
@@ -274,6 +276,10 @@ class nsHTMLDocument : public nsDocument,
   static void DocumentWriteTerminationFunc(nsISupports *aRef);
 
   already_AddRefed<nsIURI> GetDomainURI();
+  already_AddRefed<nsIURI> CreateInheritingURIForHost(const nsACString& aHostString);
+  already_AddRefed<nsIURI> RegistrableDomainSuffixOfInternal(const nsAString& aHostSuffixString,
+                                                             nsIURI* aOrigHost);
+
 
   nsresult WriteCommon(JSContext *cx, const nsAString& aText,
                        bool aNewlineTerminate);