1LWRES_GETIPNODE(3)                   BIND9                  LWRES_GETIPNODE(3)
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NAME

6       lwres_getipnodebyname, lwres_getipnodebyaddr, lwres_freehostent -
7       lightweight resolver nodename / address translation API
8

SYNOPSIS

10       #include <lwres/netdb.h>
11
12       struct hostent * lwres_getipnodebyname(const char *name, int af,
13                                              int flags, int *error_num);
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15       struct hostent * lwres_getipnodebyaddr(const void *src, size_t len,
16                                              int af, int *error_num);
17
18       void lwres_freehostent(struct hostent *he);
19

DESCRIPTION

21       These functions perform thread safe, protocol independent
22       nodename-to-address and address-to-nodename translation as defined in
23       RFC2553.
24
25       They use a struct hostent which is defined in namedb.h:
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27           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
36       The members of this structure are:
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38       h_name
39           The official (canonical) name of the host.
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41       h_aliases
42           A NULL-terminated array of alternate names (nicknames) for the
43           host.
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45       h_addrtype
46           The type of address being returned - usually PF_INET or PF_INET6.
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48       h_length
49           The length of the address in bytes.
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51       h_addr_list
52           A NULL terminated array of network addresses for the host. Host
53           addresses are returned in network byte order.
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55       lwres_getipnodebyname() looks up addresses of protocol family af for
56       the hostname name. The flags parameter contains ORed flag bits to
57       specify the types of addresses that are searched for, and the types of
58       addresses that are returned. The flag bits are:
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60       AI_V4MAPPED
61           This is used with an af of AF_INET6, and causes IPv4 addresses to
62           be returned as IPv4-mapped IPv6 addresses.
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64       AI_ALL
65           This is used with an af of AF_INET6, and causes all known addresses
66           (IPv6 and IPv4) to be returned. If AI_V4MAPPED is also set, the
67           IPv4 addresses are return as mapped IPv6 addresses.
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69       AI_ADDRCONFIG
70           Only return an IPv6 or IPv4 address if here is an active network
71           interface of that type. This is not currently implemented in the
72           BIND 9 lightweight resolver, and the flag is ignored.
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74       AI_DEFAULT
75           This default sets the AI_V4MAPPED and AI_ADDRCONFIG flag bits.
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77       lwres_getipnodebyaddr() performs a reverse lookup of address src which
78       is len bytes long.  af denotes the protocol family, typically PF_INET
79       or PF_INET6.
80
81       lwres_freehostent() releases all the memory associated with the struct
82       hostent pointer he. Any memory allocated for the h_name, h_addr_list
83       and h_aliases is freed, as is the memory for the hostent structure
84       itself.
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RETURN VALUES

87       If an error occurs, lwres_getipnodebyname() and lwres_getipnodebyaddr()
88       set *error_num to an appropriate error code and the function returns a
89       NULL pointer. The error codes and their meanings are defined in
90       <lwres/netdb.h>:
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92       HOST_NOT_FOUND
93           No such host is known.
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95       NO_ADDRESS
96           The server recognised the request and the name but no address is
97           available. Another type of request to the name server for the
98           domain might return an answer.
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100       TRY_AGAIN
101           A temporary and possibly transient error occurred, such as a
102           failure of a server to respond. The request may succeed if retried.
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104       NO_RECOVERY
105           An unexpected failure occurred, and retrying the request is
106           pointless.
107
108       lwres_hstrerror(3) translates these error codes to suitable error
109       messages.
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SEE ALSO

112       RFC2553(), lwres(3), lwres_gethostent(3), lwres_getaddrinfo(3),
113       lwres_getnameinfo(3), lwres_hstrerror(3).
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AUTHOR

116       Internet Systems Consortium, Inc.
117
119       Copyright © 2000, 2001, 2003-2005, 2007, 2014-2016, 2018 Internet
120       Systems Consortium, Inc. ("ISC")
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124ISC                               2007-06-18                LWRES_GETIPNODE(3)
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