xref: /aosp_15_r20/external/cronet/net/dns/address_sorter_posix.h (revision 6777b5387eb2ff775bb5750e3f5d96f37fb7352b)
1 // Copyright 2012 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef NET_DNS_ADDRESS_SORTER_POSIX_H_
6 #define NET_DNS_ADDRESS_SORTER_POSIX_H_
7 
8 #include <map>
9 #include <vector>
10 
11 #include "base/containers/unique_ptr_adapters.h"
12 #include "base/memory/raw_ptr.h"
13 #include "base/threading/thread_checker.h"
14 #include "net/base/ip_address.h"
15 #include "net/base/net_export.h"
16 #include "net/base/network_change_notifier.h"
17 #include "net/dns/address_sorter.h"
18 #include "net/socket/datagram_client_socket.h"
19 
20 namespace net {
21 
22 class ClientSocketFactory;
23 
24 // This implementation uses explicit policy to perform the sorting. It is not
25 // thread-safe and always completes synchronously.
26 class NET_EXPORT_PRIVATE AddressSorterPosix
27     : public AddressSorter,
28       public NetworkChangeNotifier::IPAddressObserver {
29  public:
30   // Generic policy entry.
31   struct PolicyEntry {
32     // IPv4 addresses must be mapped to IPv6.
33     unsigned char prefix[IPAddress::kIPv6AddressSize];
34     unsigned prefix_length;
35     unsigned value;
36   };
37 
38   typedef std::vector<PolicyEntry> PolicyTable;
39 
40   enum AddressScope {
41     SCOPE_UNDEFINED = 0,
42     SCOPE_NODELOCAL = 1,
43     SCOPE_LINKLOCAL = 2,
44     SCOPE_SITELOCAL = 5,
45     SCOPE_ORGLOCAL = 8,
46     SCOPE_GLOBAL = 14,
47   };
48 
49   struct SourceAddressInfo {
50     // Values read from policy tables.
51     AddressScope scope = SCOPE_UNDEFINED;
52     unsigned label = 0;
53 
54     // Values from the OS, matter only if more than one source address is used.
55     size_t prefix_length = 0;
56     bool deprecated = false;  // vs. preferred RFC4862
57     bool home = false;        // vs. care-of RFC6275
58     bool native = false;
59   };
60 
61   typedef std::map<IPAddress, SourceAddressInfo> SourceAddressMap;
62 
63   explicit AddressSorterPosix(ClientSocketFactory* socket_factory);
64 
65   AddressSorterPosix(const AddressSorterPosix&) = delete;
66   AddressSorterPosix& operator=(const AddressSorterPosix&) = delete;
67 
68   ~AddressSorterPosix() override;
69 
70   // AddressSorter:
71   void Sort(const std::vector<IPEndPoint>& endpoints,
72             CallbackType callback) const override;
73 
74  private:
75   friend class AddressSorterPosixTest;
76   class SortContext;
77 
78   // NetworkChangeNotifier::IPAddressObserver:
79   void OnIPAddressChanged() override;
80   // Fills |info| with values for |address| from policy tables.
81   void FillPolicy(const IPAddress& address, SourceAddressInfo* info) const;
82 
83   void FinishedSort(SortContext* sort_context) const;
84 
85   // Mutable to allow using default values for source addresses which were not
86   // found in most recent OnIPAddressChanged.
87   mutable SourceAddressMap source_map_;
88 
89   raw_ptr<ClientSocketFactory> socket_factory_;
90   PolicyTable precedence_table_;
91   PolicyTable label_table_;
92   PolicyTable ipv4_scope_table_;
93 
94   // SortContext stores data for an outstanding Sort() that is completing
95   // asynchronously. Mutable to allow pushing a new SortContext when Sort is
96   // called. Since Sort can be called multiple times, a container is necessary
97   // to track different SortContexts.
98   mutable std::set<std::unique_ptr<SortContext>, base::UniquePtrComparator>
99       sort_contexts_;
100 
101   THREAD_CHECKER(thread_checker_);
102 };
103 
104 }  // namespace net
105 
106 #endif  // NET_DNS_ADDRESS_SORTER_POSIX_H_
107