// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMEOS_ASH_SERVICES_SECURE_CHANNEL_WIRE_MESSAGE_H_
#define CHROMEOS_ASH_SERVICES_SECURE_CHANNEL_WIRE_MESSAGE_H_
#include <memory>
#include <string>
namespace ash::secure_channel {
// Message sent over the wire via SecureChannel. Each message sent using the
// SecureChannel protocol has a feature name (a unique identifier for the client
// sending/receiving a message) and a payload.
//
// A wire message in SecureChannel is serialized to a byte array (in the format
// of a std::string). The first byte is always the protocol version expressed as
// an unsigned 8-bit int. This class supports protocol versions 3 and 4.
//
// v3: One byte version (0x03), followed by 2 bytes of the message size as an
// unsigned 16-bit int, followed by a stringified JSON object containing a
// "feature" key whose value is the feature and a "payload" key whose value
// is the payload.
//
// [ message version ] [ body length ] [ JSON body ]
// 1 byte 2 bytes body length
//
// v4: One byte version (0x04), followed by 4 bytes of the message size as an
// unsigned 32-bit int, followed by a stringified JSON object containing a
// "feature" key whose value is the feature and a "payload" key whose value
// is the payload.
//
// [ message version ] [ body length ] [ JSON body ]
// 1 byte 4 bytes body length
//
// v3 is deprecated and all new features use v4, but we special-case features
// which were released before v4 and send them via v3 for backward
// compatibility.
class WireMessage {
public:
// Creates a WireMessage containing |payload| for feature |feature| and
// sequence number |sequence_number|.
WireMessage(const std::string& payload,
const std::string& feature,
int sequence_number);
// Creates a WireMessage containing |payload| for feature |feature|.
WireMessage(const std::string& payload, const std::string& feature);
WireMessage(const WireMessage& other);
WireMessage& operator=(const WireMessage& other);
// Creates a WireMessage containing |body| (a serialized JSON) as the message
// body.
explicit WireMessage(const std::string& body);
virtual ~WireMessage();
// Returns the deserialized message from |serialized_message|, or nullptr if
// the message is malformed. Sets |is_incomplete_message| to true if the
// message does not have enough data to parse the header, or if the message
// length encoded in the message header exceeds the size of the
// |serialized_message|.
static std::unique_ptr<WireMessage> Deserialize(
const std::string& serialized_message,
bool* is_incomplete_message);
// Returns a serialized representation of |this| message.
virtual std::string Serialize() const;
const std::string& payload() const { return payload_; }
const std::string& feature() const { return feature_; }
const std::string& body() const { return body_; }
// Will return -1 if no sequence number was passed to the constructor.
int sequence_number() const { return sequence_number_; }
private:
// The message payload.
std::string payload_;
// The feature which sends or intends to receive this message (e.g.,
// EasyUnlock).
std::string feature_;
// The message body. When this is set |payload_| and |feature_| are empty, and
// vice-versa.
std::string body_;
// Sequence number for this message; set to -1 if no sequence number if set.
int sequence_number_ = -1;
};
} // namespace ash::secure_channel
#endif // CHROMEOS_ASH_SERVICES_SECURE_CHANNEL_WIRE_MESSAGE_H_
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