1ARES_GETNAMEINFO(3) Library Functions Manual ARES_GETNAMEINFO(3)
2
6 ares_getnameinfo - Address-to-nodename translation in protocol-indepen‐
7 dent manner
8
10 #include <ares.h>
11 typedef void (*ares_nameinfo_callback)(void *arg, int status,
13 int timeouts, char *node, char *service)
14 void ares_getnameinfo(ares_channel channel, const struct sockaddr *sa,
16 ares_socklen_t salen, int flags, ares_nameinfo_callback callback,
17 void *arg)
18
20 The ares_getnameinfo function is defined for protocol-independent
21 address translation. The function is a combination of ares_gethost‐
22 byaddr(3) and getservbyport(3). The function will translate the address
23 either by executing a host query on the name service channel identified
24 by channel or it will attempt to resolve it locally if possible. The
25 parameters sa and len give the address as a sockaddr structure, and
26 flags gives the options that the function will use. Valid flags are
27 listed below:
28 ARES_NI_NOFQDN Only the nodename portion of the FQDN is returned
30 for local hosts.
31 ARES_NI_NUMERICHOST
33 The numeric form of the hostname is returned rather
34 than the name.
35 ARES_NI_NAMEREQD An error is returned if the hostname cannot be found
37 in the DNS.
38 ARES_NI_NUMERICSERV
40 The numeric form of the service is returned rather
41 than the name.
42 ARES_NI_TCP The service name is to be looked up for the TCP pro‐
44 tocol.
45 ARES_NI_UDP The service name is to be looked up for the UDP pro‐
47 tocol.
48 ARES_NI_SCTP The service name is to be looked up for the SCTP
50 protocol.
51 ARES_NI_DCCP The service name is to be looked up for the DCCP
53 protocol.
54 ARES_NI_NUMERICSCOPE
56 The numeric form of the scope ID is returned rather
57 than the name.
58 ARES_NI_LOOKUPHOST A hostname lookup is being requested.
60 ARES_NI_LOOKUPSERVICE
62 A service name lookup is being requested.
63 When the query is complete or has failed, the ares library will invoke
65 callback. Completion or failure of the query may happen immediately,
66 or may happen during a later call to ares_process(3), ares_destroy(3)
67 or ares_cancel(3).
68 The callback argument arg is copied from the ares_getnameinfo argument
70 arg. The callback argument status indicates whether the query suc‐
71 ceeded and, if not, how it failed. It may have any of the following
72 values:
73 ARES_SUCCESS The host lookup completed successfully.
75 ARES_ENOTIMP The ares library does not know how to look up
77 addresses of type family.
78 ARES_ENOTFOUND The address addr was not found.
80 ARES_ENOMEM Memory was exhausted.
82 ARES_ECANCELLED The query was cancelled.
84 ARES_EDESTRUCTION The name service channel channel is being destroyed;
86 the query will not be completed.
87 ARES_EBADFLAGS The flags parameter contains an illegal value.
89 The callback argument timeouts reports how many times a query timed out
91 during the execution of the given request.
92 On successful completion of the query, the callback argument node con‐
94 tains a string representing the hostname (assuming ARES_NI_LOOKUPHOST
95 was specified). Additionally, service contains a string representing
96 the service name (assuming ARES_NI_LOOKUPSERVICE was specified). If
97 the query did not complete successfully, or one of the values was not
98 requested, node or service will be NULL.
99
101 ares_process(3),
102
104 Dominick Meglio
105 Copyright 2005 by Dominick Meglio.
106 1 May 2009 ARES_GETNAMEINFO(3)