chromium/net/dns/dns_hosts.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DNS_DNS_HOSTS_H_
#define NET_DNS_DNS_HOSTS_H_

#include <stddef.h>

#include <string>
#include <string_view>
#include <unordered_map>
#include <utility>

#include "base/files/file_path.h"
#include "net/base/address_family.h"
#include "net/base/ip_address.h"
#include "net/base/net_export.h"

namespace net {

DnsHostsKey;

struct DnsHostsKeyHash { … };

// There are OS-specific variations in how commas in the hosts file behave.
enum ParseHostsCommaMode { … };

// Parsed results of a Hosts file.
//
// Although Hosts files map IP address to a list of domain names, for name
// resolution the desired mapping direction is: domain name to IP address.
// When parsing Hosts, we apply the "first hit" rule as Windows and glibc do.
// With a Hosts file of:
// 300.300.300.300 localhost # bad ip
// 127.0.0.1 localhost
// 10.0.0.1 localhost
// The expected resolution of localhost is 127.0.0.1.
DnsHosts;

// Parses |contents| (as read from /etc/hosts or equivalent) and stores results
// in |dns_hosts|. Invalid lines are ignored (as in most implementations).
// Overrides the OS-specific default handling of commas, so unittests can test
// both modes.
void NET_EXPORT_PRIVATE ParseHostsWithCommaModeForTesting(
    const std::string& contents,
    DnsHosts* dns_hosts,
    ParseHostsCommaMode comma_mode);

// Parses |contents| (as read from /etc/hosts or equivalent) and stores results
// in |dns_hosts|. Invalid lines are ignored (as in most implementations).
void NET_EXPORT_PRIVATE ParseHosts(const std::string& contents,
                                   DnsHosts* dns_hosts);

// Test-injectable HOSTS parser.
class NET_EXPORT_PRIVATE DnsHostsParser { … };

// Implementation of `DnsHostsParser` that reads HOSTS from a given file.
class NET_EXPORT_PRIVATE DnsHostsFileParser : public DnsHostsParser { … };

}  // namespace net

#endif  // NET_DNS_DNS_HOSTS_H_