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
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
|
#include <util/memory/tempbuf.h>
#include <util/generic/singleton.h>
#include <util/generic/yexception.h>
#include <util/network/ip.h>
#if defined(_unix_)
#include <unistd.h>
#include <ifaddrs.h>
#include <netdb.h>
#endif
#if defined(_win_)
#include <WinSock2.h>
#endif
#include "defaults.h"
#include "yassert.h"
#include "hostname.h"
namespace {
struct THostNameHolder {
inline THostNameHolder() {
TTempBuf hostNameBuf;
if (gethostname(hostNameBuf.Data(), hostNameBuf.Size() - 1)) {
ythrow TSystemError() << "can not get host name";
}
HostName = hostNameBuf.Data();
}
TString HostName;
};
struct TFQDNHostNameHolder {
inline TFQDNHostNameHolder() {
char buf[1024];
memset(buf, 0, sizeof(buf));
int res = gethostname(buf, sizeof(buf) - 1);
if (res) {
ythrow TSystemError() << "can not get hostname";
}
#ifdef _darwin_
// On Darwin gethostname returns fqdn, see hostname.c in shell_cmds:
// https://github.com/apple-oss-distributions/shell_cmds/blob/main/hostname/hostname.c
// There are macs in the wild that don't have fqdn hostnames, but
// which have search domains in their resolv.conf, so any attempt to
// resolve AI_CANONNAME for the short hostname will result in the
// EAI_NONAME error.
// It seems using gethostname is enough to emulate the result of
// `hostname -f`, which still works on those macs.
FQDNHostName = buf;
#else
// On Linux `hostname -f` calls getaddrinfo with AI_CANONNAME flag
// to find the fqdn and will fail on any error.
// Hosts often have a short hostname and fqdn is resolved over dns.
// It is also very common to have a short hostname alias in
// /etc/hosts, which works as a fallback (e.g. no fqdn in search
// domains, otherwise `hostname -f` fails with an error and it is
// obvious the host is not configured correctly).
// Note that getaddrinfo may sometimes return EAI_NONAME even when
// host actually has fqdn, but dns is temporary unavailable, so we
// cannot ignore any errors on Linux.
struct addrinfo hints;
struct addrinfo* ais{nullptr};
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_flags = AI_CANONNAME;
res = getaddrinfo(buf, nullptr, &hints, &ais);
if (res) {
ythrow TSystemError() << "can not get FQDN (return code is " << res << ", hostname is \"" << buf << "\")";
}
FQDNHostName = ais->ai_canonname;
FQDNHostName.to_lower();
freeaddrinfo(ais);
#endif
}
TString FQDNHostName;
};
} // namespace
const TString& HostName() {
return (Singleton<THostNameHolder>())->HostName;
}
const char* GetHostName() {
return HostName().data();
}
const TString& FQDNHostName() {
return (Singleton<TFQDNHostNameHolder>())->FQDNHostName;
}
const char* GetFQDNHostName() {
return FQDNHostName().data();
}
bool IsFQDN(const TString& name) {
TString absName = name;
if (!absName.EndsWith('.')) {
absName.append(".");
}
try {
// ResolveHost() can't be used since it is ipv4-only, port is not important
TNetworkAddress addr(absName, 0);
} catch (const TNetworkResolutionError&) {
return false;
}
return true;
}
|
