1getnameinfo(3XNET)X/Open Networking Services Library Functionsgetnameinfo(3XNET)
2
6 getnameinfo - get name information
7
9 cc [ flag ... ] file ... -lxnet [ library ... ]
10 #include <sys/socket.h>
11 #include <netdb.h>
12 int getnameinfo(const struct sockaddr *restrict sa, socklen_t salen,
14 char *restrict node, socklen_t nodelen, char *restrict service,
15 socklen_t servicelen, unsigned flags);
16
19 The getnameinfo() function translates a socket address to a node name
20 and service location, all of which are defined as in getad‐
21 drinfo(3XNET).
22 The sa argument points to a socket address structure to be translated.
25 If the socket address structure contains an IPv4-mapped IPv6 address or
26 an IPv4-compatible IPv6 address, the implementation extracts the embed‐
27 ded IPv4 address and lookup the node name for that IPv4 address.
28 If the node argument is non-NULL and the nodelen argument is non-zero,
31 then the node argument points to a buffer able to contain up to nodelen
32 characters that receives the node name as a null-terminated string. If
33 the node argument is NULL or the nodelen argument is zero, the node
34 name is not returned. If the node's name cannot be located, the numeric
35 form of the node's address is returned instead of its name.
36 If the service argument is non-NULL and the servicelen argument is non-
39 zero, then the service argument points to a buffer able to contain up
40 to servicelen bytes that receives the service name as a null-terminated
41 string. If the service argument is NULL or the servicelen argument is
42 zero, the service name is not returned. If the service's name cannot be
43 located, the numeric form of the service address (for example, its port
44 number) is returned instead of its name.
45 The flags argument is a flag that changes the default actions of the
48 function. By default the fully-qualified domain name (FQDN) for the
49 host is returned, but:
50 o If the flag bit NI_NOFQDN is set, only the node name portion
52 of the FQDN is returned for local hosts.
53 o If the flag bit NI_NUMERICHOST is set, the numeric form of
55 the host's address is returned instead of its name, under
56 all circumstances.
57 o If the flag bit NI_NAMEREQD is set, an error is returned if
59 the host's name cannot be located.
60 o If the flag bit NI_NUMERICSERV is set, the numeric form of
62 the service address is returned (for example, its port num‐
63 ber) instead of its name, under all circumstances.
64 o If the flag bit NI_DGRAM is set, this indicates that the
66 service is a datagram service (SOCK_DGRAM). The default
67 behavior assumes that the service is a stream service
68 (SOCK_STREAM).
69
71 A 0 return value for getnameinfo() indicates successful completion; a
72 non-zero return value indicates failure. The possible values for the
73 failures are listed in the ERRORS section.
74 Upon successful completion, getnameinfo() returns the node and service
77 names, if requested, in the buffers provided. The returned names are
78 always null-terminated strings.
79
81 The getnameinfo() function will fail if:
82 EAI_AGAIN The name could not be resolved at this time. Future
84 attempts might succeed.
85 EAI_BADFLAGS The flags argument had an invalid value.
88 EAI_FAIL A non-recoverable error occurred.
91 EAI_FAMILY The address family was not recognized or the address
94 length was invalid for the specified family.
95 EAI_MEMORY There was a memory allocation failure.
98 EAI_NONAME The name does not resolve for the supplied parameters.
101 NI_NAMEREQD is set and the host's name cannot be
102 located, or both nodename and servname were NULL.
103 EAI_SYSTEM A system error occurred. The error code can be found in
106 errno.
107
110 If the returned values are to be used as part of any further name reso‐
111 lution (for example, passed to getaddrinfo()), applications should pro‐
112 vide buffers large enough to store any result possible on the system.
113 Given the IPv4-mapped IPv6 address "::ffff:1.2.3.4", the implementation
116 performs a lookup as if the socket address structure contains the IPv4
117 address "1.2.3.4".
118
120 See attributes(5) for descriptions of the following attributes:
121 ┌─────────────────────────────┬─────────────────────────────┐
126 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
127 ├─────────────────────────────┼─────────────────────────────┤
128 │Interface Stability │Standard │
129 ├─────────────────────────────┼─────────────────────────────┤
130 │MT-Level │MT-Safe │
131 └─────────────────────────────┴─────────────────────────────┘
132
134 gai_strerror(3XNET), getaddrinfo(3XNET), getservbyname(3XNET),
135 socket(3XNET), attributes(5), standards(5)
136
138 The IPv6 unspecified address ("::") and the IPv6 loopback address
139 ("::1") are not IPv4-compatible addresses. If the address is the IPv6
140 unspecified address ("::"), a lookup is not performed, and the EAI_NO‐
141 NAME error is returned.
142 The two NI_NUMERICxxx flags are required to support the -n flag that
145 many commands provide.
146 The NI_DGRAM flag is required for the few AF_INET and AF_INET6 port
149 numbers (for example, [512,514]) that represent different services for
150 UDP and TCP.
151SunOS 5.11 1 Nov 2003 getnameinfo(3XNET)