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