library/cpp/dns/cache.h


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45

#pragma once 
 
#include <util/network/socket.h> 
#include <util/generic/strbuf.h> 
#include <util/generic/string.h>
 
namespace NDns {
    struct TResolveInfo { 
        inline TResolveInfo(const TStringBuf& host, ui16 port) 
            : Host(host) 
            , Port(port) 
        { 
        } 
 
        TStringBuf Host; 
        ui16 Port; 
    }; 
 
    struct TResolvedHost { 
        inline TResolvedHost(const TString& host, const TNetworkAddress& addr) noexcept
            : Host(host)
            , Addr(addr)
            , Id(0)
        { 
        } 
 
        TString Host; //resolved hostname (from TResolveInfo, - before aliasing)
        TNetworkAddress Addr; 
        size_t Id; //cache record id
    }; 
 
    // Resolving order:
    //   1. check local thread cache, return if found
    //   2. check global cache, return if found
    //   3. search alias for hostname, if found, continue resolving alias
    //   4. normal resolver
    const TResolvedHost* CachedResolve(const TResolveInfo& ri);

    //like previous, but at stage 4 use separate thread for resolving (created on first usage)
    //useful in green-threads with tiny stack
    const TResolvedHost* CachedThrResolve(const TResolveInfo& ri);

    //create alias for host, which can be used for static resolving (when alias is ip address)
    void AddHostAlias(const TString& host, const TString& alias);
}