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// Copyright 2020 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 DISCOVERY_COMMON_CONFIG_H_
#define DISCOVERY_COMMON_CONFIG_H_
#include <vector>
#include "platform/base/interface_info.h"
namespace openscreen {
namespace discovery {
// This struct provides parameters needed to initialize the discovery pipeline.
struct Config {
/*****************************************
* Common Settings
*****************************************/
// Interfaces on which services should be published, and on which discovery
// should listen for announced service instances.
std::vector<InterfaceInfo> network_info;
// Maximum allowed size in bytes for the rdata in an incoming record. All
// received records with rdata size exceeding this size will be dropped.
// The default value is taken from RFC 6763 section 6.2.
int maximum_valid_rdata_size = 1300;
/*****************************************
* Publisher Settings
*****************************************/
// Determines whether publishing of services is enabled.
bool enable_publication = true;
// Number of times new mDNS records should be announced, using an exponential
// back off. See RFC 6762 section 8.3 for further details. Per RFC, this value
// is expected to be in the range of 2 to 8.
int new_record_announcement_count = 8;
// Maximum number of truncated messages that the receiver may receive for a
// single query from any given host.
// The supported record type with the largest expected data size is a TXT
// record. RFC 6763 section 6.1 states that the "maximum sensible size" for
// one such record is "a few hundred bytes". Given that an mDNS Message's size
// is bounded by 9000 bytes, each message can be expected to hold at least 30
// records, meaning that the default value of 8 allows for 240 records, or
// more in the case of non-TXT records.
int maximum_truncated_messages_per_query = 8;
// Maximum number of concurrent truncated queries that may be tracked by a
// single network interface.
// By the same logic stated in the above config value, truncated queries
// should be relatively rare. Each truncated query lives for at most one
// second after the last truncated packet is received, so receiving 64 such
// queries in a short timespan is unlinkely.
int maximum_concurrent_truncated_queries_per_interface = 64;
// Maximum number of known answers allowed for a given truncated query.
// A default value of 256 is used because this is the maximum number of
// devices on a LAN.
int maximum_known_answer_records_per_query = 256;
/*****************************************
* Querier Settings
*****************************************/
// Determines whether querying is enabled.
bool enable_querying = true;
// Number of times new mDNS records should be announced, using an exponential
// back off. -1 signifies that there should be no maximum.
int new_query_announcement_count = -1;
// Limit on the size to which the mDNS Querier Cache may grow. This is used to
// prevent a malicious or misbehaving mDNS client from causing the memory
// used by mDNS to grow in an unbounded fashion.
int querier_max_records_cached = 1024;
// Sets the querier to ignore all NSEC negative response records received as
// responses to outgoing queries.
bool ignore_nsec_responses = false;
};
} // namespace discovery
} // namespace openscreen
#endif // DISCOVERY_COMMON_CONFIG_H_
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