Extract Certificate Transparency SCTs from stapled OCSP responses

net/cert/ct_objects_extractor.h

Index: net/cert/ct_objects_extractor.h
diff --git a/net/cert/ct_objects_extractor.h b/net/cert/ct_objects_extractor.h
index de47c8521770f048cd3a9a70450749175947ec19..6a9cc11db5f4f0886c1f5238d9f6072a2a47285b 100644
--- a/net/cert/ct_objects_extractor.h
+++ b/net/cert/ct_objects_extractor.h
@@ -45,6 +45,26 @@ NET_EXPORT_PRIVATE bool GetPrecertLogEntry(X509Certificate::OSCertHandle leaf,
 NET_EXPORT_PRIVATE bool GetX509LogEntry(X509Certificate::OSCertHandle leaf,
                                         LogEntry* result);
 
+// Extracts a SignedCertificateTimestampList that has been embedded within
+// an OCSP response as an extension with the OID 1.3.6.1.4.1.11129.2.4.5.
+// If the extension is present, and matches the serial number of the leaf
+// certificate, returns true, updating |*sct_list| to contain
+// the encoded list, minus the DER encoding necessary for the extension.
+// |*sct_list| can then be further decoded with ct::DecodeSCTList.
+//
+// TODO(ekasper): change this to match by the entire CertID in an OCSP response.
+// We currently do response matching by serial number only, so if the response
+// contains statuses for different certificates with the same serial number,
+// this method does not work. However, repeating serial numbers within the same
+// OCSP response are unlikely to begin with (different CAs would have to be
+// using the same serial number AND delegating to the same OCSP responder),
+// and since CT further only uses stapled OCSP responses which are known to
+// pertain to the server (leaf) certificate, this is a very low concern for us.
+NET_EXPORT_PRIVATE bool ExtractSCTListFromOCSPResponse(
+    X509Certificate::OSCertHandle leaf,

[wtc, 2013/12/03 21:04:25]

Nit: If CT can also be used for CA certificates, I suggest renaming this
parameter |cert| to be more general.

If you rename it, you should update the comment "the serial number of the leaf
certificate" on lines 50-51 accordingly.

[ekasper, 2013/12/04 19:25:15]

I've changed it to take a serial number directly.

+    const std::string& ocsp_response,
+    std::string* sct_list);
+
 }  // namespace ct
 
 }  // namespace net