// Copyright 2021 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

syntax = "proto2";

option optimize_for = LITE_RUNTIME;

package reporting;

import "record_constants.proto";

// Record represents the data sent from the Reporting Client.
message Record {
  // Record data as enqueued with an ReportingQueue::Enqueue call (required).
  // Data structure requirements are set by the destination. For destinations
  // expecting a proto - the proto will be MessageLite::SerializeToString(), and
  // will be DeserializedFromString() in the destination handler, prior to being
  // forwarded.
  //
  // Current expected formats (destination : type):
  // Destination::UPLOAD_EVENTS : UploadEventsRequest
  optional bytes data = 1;

  // The destination associated with this request as set with the
  // ReportingQueueConfiguration (required).
  optional Destination destination = 2;

  // The DMToken associated with this request as set with the
  // ReportingQueueConfiuguration (required).
  optional string dm_token = 3;

  // When the record was submitted to ReportingQueue::Enqueue.
  // Represents UTC time since Unix epoch 1970-01-01T00:00:00Z in microseconds,
  // to match Spanner timestamp format.
  optional int64 timestamp_us = 4;
}

// A Record with it's digest and the digest of the previous record.
message WrappedRecord {
  // Record (required)
  // Data provided by the Reporting Client.
  optional Record record = 1;

  // Record Digest (required)
  // SHA256 hash used to validate that the record has been retrieved without
  // being manipulated while it was on the device or during transfer.
  optional bytes record_digest = 2;

  // Last record digest (required)
  // Created by client and used by server to verify that the sequence of records
  // has not been tampered with.
  optional bytes last_record_digest = 3;
}

// Information about how the record was encrypted.
message EncryptionInfo {
  // Encryption key (optional).
  // Represents the client's X25519 public key used along with the server's
  // private key (identified by |public_key_id|) for shared secret recreation
  // by the server to get the symmetric key used for |encrypted_wrapped_record|
  // encryption.
  optional bytes encryption_key = 1;

  // Public key id (optional)
  // Hash of the public key used to do encryption. Used to identity the
  // private key for decryption. If no key_id is present, it is assumed that
  // |key| has been transferred in plaintext.
  optional int64 public_key_id = 2;
}

// Tracking information for what order a record appears in.
message SequencingInformation {
  // Sequencing ID (monotonic number, required)
  // Tracks records processing progress and is used for confirming that this
  // and all prior records have been processed. If the same number is
  // encountered more than once, only one instance needs to be processed. If
  // certain number is absent when higher are encountered, it indicates that
  // some records have been lost and there is a gap in the records stream
  // (what to do with that is a decision that the caller needs to make).
  optional int64 sequencing_id = 1;

  // Generation ID (required). Unique per device and priority. Generated anew
  // when previous record digest is not found at startup (e.g. after powerwash).
  optional int64 generation_id = 2;

  // Priority (required).
  optional Priority priority = 3;
}

// Envelope for the |WrappedRecord| and associated metadata as it is stored on
// disk and sent to the server.
message EncryptedRecord {
  // Encrypted Wrapped Record
  // |WrappedRecord| encrypted with the |encryption_key| in |encryption_info|.
  // When absent, indicates gap - respective record is irreparably corrupt or
  // missing from Storage, and server side should log it as such and no longer
  // expect client to deliver it.
  optional bytes encrypted_wrapped_record = 1;

  // Must be present to facilitate decryption of encrypted record.
  // If missing, the record is either not encrypted or missing.
  // TODO(b/153651358): Disable an option to send record not encrypted.
  optional EncryptionInfo encryption_info = 2;

  // Sequencing information (required). Must be present to allow
  // tracking and confirmation of the events by server.
  optional SequencingInformation sequencing_information = 3;

  // Compression information (optional).
  optional CompressionInformation compression_information = 4;
}

// Tracking information for what compression is used.
message CompressionInformation {
  // Compression algorithms available for use
  enum CompressionAlgorithm {
    COMPRESSION_NONE = 0;
    COMPRESSION_SNAPPY = 1;
  }

  // Compression algorithm that is used if the record was
  // compressed before being wrapped (optional).
  optional CompressionAlgorithm compression_algorithm = 1;
}

// Encryption public key as delivered from the server and stored in Storage.
// Signature ensures the key was actually sent by the server and not manipulated
// afterwards.
message SignedEncryptionInfo {
  // Public asymmetric key (required).
  optional bytes public_asymmetric_key = 1;

  // Public key id (required).
  // Identifies private key matching |public_asymmetric_key| for the server.
  // Matches Encryptor::PublicKeyId.
  optional int32 public_key_id = 2;

  // Signature of |public_asymmetric_key| (required).
  // Verified by client against a well-known signature.
  optional bytes signature = 3;
}