1LWRES_GETIPNODE(3) BIND9 LWRES_GETIPNODE(3)
2
6 lwres_getipnodebyname, lwres_getipnodebyaddr, lwres_freehostent -
7 lightweight resolver nodename / address translation API
8
10 #include <lwres/netdb.h>
11 struct hostent * lwres_getipnodebyname(const char *name, int af,
13 int flags, int *error_num);
14 struct hostent * lwres_getipnodebyaddr(const void *src, size_t len,
16 int af, int *error_num);
17 void lwres_freehostent(struct hostent *he);
19
21 These functions perform thread safe, protocol independent
22 nodename-to-address and address-to-nodename translation as defined in
23 RFC2553.
24 They use a struct hostent which is defined in namedb.h:
26 struct hostent {
28 char *h_name; /* official name of host */
29 char **h_aliases; /* alias list */
30 int h_addrtype; /* host address type */
31 int h_length; /* length of address */
32 char **h_addr_list; /* list of addresses from name server */
33 };
34 #define h_addr h_addr_list[0] /* address, for backward compatibility */
35 The members of this structure are:
38 h_name
40 The official (canonical) name of the host.
41 h_aliases
43 A NULL-terminated array of alternate names (nicknames) for the
44 host.
45 h_addrtype
47 The type of address being returned - usually PF_INET or PF_INET6.
48 h_length
50 The length of the address in bytes.
51 h_addr_list
53 A NULL terminated array of network addresses for the host. Host
54 addresses are returned in network byte order.
55 lwres_getipnodebyname() looks up addresses of protocol family af for
57 the hostname name. The flags parameter contains ORed flag bits to
58 specify the types of addresses that are searched for, and the types of
59 addresses that are returned. The flag bits are:
60 AI_V4MAPPED
62 This is used with an af of AF_INET6, and causes IPv4 addresses to
63 be returned as IPv4-mapped IPv6 addresses.
64 AI_ALL
66 This is used with an af of AF_INET6, and causes all known addresses
67 (IPv6 and IPv4) to be returned. If AI_V4MAPPED is also set, the
68 IPv4 addresses are return as mapped IPv6 addresses.
69 AI_ADDRCONFIG
71 Only return an IPv6 or IPv4 address if here is an active network
72 interface of that type. This is not currently implemented in the
73 BIND 9 lightweight resolver, and the flag is ignored.
74 AI_DEFAULT
76 This default sets the AI_V4MAPPED and AI_ADDRCONFIG flag bits.
77 lwres_getipnodebyaddr() performs a reverse lookup of address src which
79 is len bytes long. af denotes the protocol family, typically PF_INET
80 or PF_INET6.
81 lwres_freehostent() releases all the memory associated with the struct
83 hostent pointer he. Any memory allocated for the h_name, h_addr_list
84 and h_aliases is freed, as is the memory for the hostent structure
85 itself.
86
88 If an error occurs, lwres_getipnodebyname() and lwres_getipnodebyaddr()
89 set *error_num to an appropriate error code and the function returns a
90 NULL pointer. The error codes and their meanings are defined in
91 <lwres/netdb.h>:
92 HOST_NOT_FOUND
94 No such host is known.
95 NO_ADDRESS
97 The server recognised the request and the name but no address is
98 available. Another type of request to the name server for the
99 domain might return an answer.
100 TRY_AGAIN
102 A temporary and possibly transient error occurred, such as a
103 failure of a server to respond. The request may succeed if retried.
104 NO_RECOVERY
106 An unexpected failure occurred, and retrying the request is
107 pointless.
108 lwres_hstrerror(3) translates these error codes to suitable error
110 messages.
111
113 RFC2553(), lwres(3), lwres_gethostent(3), lwres_getaddrinfo(3),
114 lwres_getnameinfo(3), lwres_hstrerror(3).
115
117 Copyright © 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
118 Copyright © 2000, 2001, 2003 Internet Software Consortium.
119BIND9 Jun 30, 2000 LWRES_GETIPNODE(3)