Certificate Transparency: Fetching of Signed Tree Heads (DRAFT)

net/cert/ct_verifier.h

Index: net/cert/ct_verifier.h
diff --git a/net/cert/ct_verifier.h b/net/cert/ct_verifier.h
index 290a0474a649138733c902fdc5a8e47b6210f12d..18e187b07f9aae30ab1b2e3597cda2d1e779c1d1 100644
--- a/net/cert/ct_verifier.h
+++ b/net/cert/ct_verifier.h
@@ -5,21 +5,26 @@
 #ifndef NET_CERT_CT_VERIFIER_H_
 #define NET_CERT_CT_VERIFIER_H_
 
+#include "base/memory/ref_counted.h"
+#include "base/observer_list.h"
 #include "net/base/net_export.h"
 
 namespace net {
 
 namespace ct {
 struct CTVerifyResult;
+struct SignedCertificateTimestamp;
 }  // namespace ct
 
 class BoundNetLog;
+class CTLogVerifier;
 class X509Certificate;
 
 // Interface for verifying Signed Certificate Timestamps over a certificate.
 class NET_EXPORT CTVerifier {
  public:
-  virtual ~CTVerifier() {}
+  CTVerifier();

[Ryan Sleevi, 2015/04/24 10:42:08]

DESIGN: This mixes interface with implementation

That is, this used to be a pure virtual class, now it's a pure virtual with
public virtual. I think we need to rethinking this; lets chat.

[Eran Messeri, 2015/06/18 15:18:42]

Done - this class remains pure virtual (without any data members); I have left
the SetObserver here as I expect every implementation will notify the observer
of new SCTs.

+  virtual ~CTVerifier();
 
   // Verifies SCTs embedded in the certificate itself, SCTs embedded in a
   // stapled OCSP response, and SCTs obtained via the
@@ -36,6 +41,39 @@ class NET_EXPORT CTVerifier {
                      const std::string& sct_list_from_tls_extension,
                      ct::CTVerifyResult* result,
                      const BoundNetLog& net_log) = 0;
+
+  class NET_EXPORT Observer {

[Ryan Sleevi, 2015/04/24 10:42:08]

http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Declaration_O...

[Eran Messeri, 2015/06/18 15:18:43]

Done.

+   public:
+    virtual ~Observer() {}
+
+    virtual void OnSCTVerified(const ct::SignedCertificateTimestamp* sct,
+                               CTLogVerifier* verifier) {}
+
+   protected:
+    Observer() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Observer);
+  };
+
+  // Registers |observer| to receive notifications of validated SCTs. The
+  // thread on which this is called is the thread on which |observer| will be
+  // called back with notifications.
+  void AddObserver(Observer* observer);

[Ryan Sleevi, 2015/04/24 10:42:08]

Will there ever be more than one observer at a time with your API contract?

If not, let's look at alternatives.

[Eran Messeri, 2015/06/18 15:18:43]

No - changed to only having one.

+
+  // Unregisters |observer| from receiving notifications. This must be called
+  // on the same thread on which AddObserver() was called.
+  void RemoveObserver(Observer* observer);
+
+ protected:
+  void NotifyObserversOfSCTVerified(
+      scoped_refptr<ct::SignedCertificateTimestamp> sct,
+      CTLogVerifier* verifier);
+
+ private:
+  ObserverList<Observer> observer_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(CTVerifier);
 };
 
 }  // namespace net