Add parsers for the Encryption and Encryption-Key HTTP headers.

components/gcm_driver/crypto/encryption_header_parsers.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_GCM_DRIVER_CRYPTO_ENCRYPTION_HEADER_PARSERS_H_
+#define COMPONENTS_GCM_DRIVER_CRYPTO_ENCRYPTION_HEADER_PARSERS_H_
+
+#include <stdint.h>

[whywhat, 2015/09/14 14:57:43]

can we include <cstdint> ? (.h is much more common throughout the codebase)

[Peter Beverloo, 2015/09/15 19:41:11]

That just includes stdint.h, except that it also puts the types in the std::
namespace. stdint.h is the canonical one in Chromium :).

+#include <string>
+
+namespace gcm {
+
+// Parses |input| following the syntax of the Encryption HTTP header. Chrome
+// only supports a single set of properties to be read from the header at this
+// time. The base64url encoded salt will be decoded, |rs| will be validated.

[whywhat, 2015/09/14 14:57:43]

s/salt/|salt|? what about |keyid|?

[Peter Beverloo, 2015/09/15 19:41:11]

s/|rs|/rs/ in fact. This part of the comment refers to the input parsed from the
header, not to the values written to the out arguments.

+//
+// https://tools.ietf.org/html/draft-thomson-http-encryption-01#section-3
+//
+// Returns whether the |input| could successfully be parsed, and the resulting

[whywhat, 2015/09/14 14:57:43]

s/could successfully be parsed/was (or has been) successfully parsed
Do you want to say something that if the returned value is false, the output
parameters remain unchanged?

[Peter Beverloo, 2015/09/15 19:41:11]

Done.

+// information was stored in |keyid|, |salt| and |rs|.
+bool ParseEncryptionHeader(const std::string& input,
+                           std::string* keyid,
+                           std::string* salt,
+                           int64_t* rs);
+
+// Parses |input| following the syntax of the Encryption-Key HTTP header. Chrome
+// only supports a single set of properties to be read from the header at this
+// time. The base64url encoded key and dh will be decoded.

[whywhat, 2015/09/14 14:57:43]

s/key/|key| and s/dh/|dh|?
Mostly to be consistent with the comment above.

[Peter Beverloo, 2015/09/15 19:41:11]

Acknowledged.

+//
+// https://tools.ietf.org/html/draft-thomson-http-encryption-01#section-4
+//
+// Returns whether |input| could be successfully parsed, and the resulting

[whywhat, 2015/09/14 14:57:43]

ditto about the phrasing and the return value

[Peter Beverloo, 2015/09/15 19:41:11]

Done.

+// information was stored in |keyid|, |key| and |dh|.
+bool ParseEncryptionKeyHeader(const std::string& input,
+                              std::string* keyid,
+                              std::string* key,
+                              std::string* dh);
+
+}  // namespace gcm
+
+#endif  // COMPONENTS_GCM_DRIVER_CRYPTO_ENCRYPTION_HEADER_PARSERS_H_