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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 NET_DNS_DNS_RESPONSE_RESULT_EXTRACTOR_H_
#define NET_DNS_DNS_RESPONSE_RESULT_EXTRACTOR_H_
#include <stdint.h>
#include "net/base/net_export.h"
#include "net/dns/host_cache.h"
#include "net/dns/public/dns_query_type.h"
namespace net {
class DnsResponse;
// Higher-level parser to take a DnsResponse and extract results.
class NET_EXPORT_PRIVATE DnsResponseResultExtractor {
public:
enum class ExtractionError {
kOk = 0,
// Record failed to parse.
kMalformedRecord,
// Malformed CNAME
kMalformedCname,
// Found CNAME or result record with an unexpected name.
kNameMismatch,
// Malformed result record
kMalformedResult,
// CNAME record after a result record
kCnameAfterResult,
// Multiple CNAME records for the same owner name.
kMultipleCnames,
// Invalid alias chain, e.g. contains loops or disjoint aliases.
kBadAliasChain,
// Not expected. Used for DCHECKs.
kUnexpected,
};
explicit DnsResponseResultExtractor(const DnsResponse* response);
~DnsResponseResultExtractor();
DnsResponseResultExtractor(const DnsResponseResultExtractor&) = delete;
DnsResponseResultExtractor& operator=(const DnsResponseResultExtractor&) =
delete;
// Extract results from the response. `query_type` must match the qtype from
// the DNS query, and it must have already been validated (expected to be done
// by DnsTransaction) that the response matches the query.
//
// May have the side effect of recording metrics about DnsResponses as they
// are parsed, so while not an absolute requirement, any given DnsResponse
// should only be used and extracted from at most once.
ExtractionError ExtractDnsResults(DnsQueryType query_type,
HostCache::Entry* out_results) const;
// Creates the results of a NODATA response (successfully parsed but without
// any results) appropriate for `query_type`.
static HostCache::Entry CreateEmptyResult(DnsQueryType query_type);
private:
const DnsResponse* const response_;
};
} // namespace net
#endif // NET_DNS_DNS_RESPONSE_RESULT_EXTRACTOR_H_
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