1GETIPNODEBYNAME(3)         Linux Programmer's Manual        GETIPNODEBYNAME(3)
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3
4

NAME

6       getipnodebyname,  getipnodebyaddr,  freehostent - get network hostnames
7       and addresses
8

SYNOPSIS

10       #include <sys/types.h>
11       #include <sys/socket.h>
12       #include <netdb.h>
13
14       struct hostent *getipnodebyname(const char *name, int af,
15                                       int flags, int *error_num);
16
17       struct hostent *getipnodebyaddr(const void *addr, size_t len,
18                                       int af, int *error_num);
19
20       void freehostent(struct hostent *ip);
21

DESCRIPTION

23       These functions are deprecated (and unavailable in glibc).  Use  getad‐
24       drinfo(3) and getnameinfo(3) instead.
25
26       The  getipnodebyname() and getipnodebyaddr() functions return the names
27       and addresses of a network host.  These functions return a  pointer  to
28       the following structure:
29
30           struct hostent {
31               char  *h_name;
32               char **h_aliases;
33               int    h_addrtype;
34               int    h_length;
35               char **h_addr_list;
36           };
37
38       These functions replace the gethostbyname(3) and gethostbyaddr(3) func‐
39       tions, which could access only the IPv4 network  address  family.   The
40       getipnodebyname()  and  getipnodebyaddr() functions can access multiple
41       network address families.
42
43       Unlike the gethostby functions,  these  functions  return  pointers  to
44       dynamically  allocated  memory.   The freehostent() function is used to
45       release the dynamically allocated memory after  the  caller  no  longer
46       needs the hostent structure.
47
48   getipnodebyname() arguments
49       The  getipnodebyname() function looks up network addresses for the host
50       specified by the name argument.  The af argument specifies one  of  the
51       following values:
52
53       AF_INET
54              The name argument points to a dotted-quad IPv4 address or a name
55              of an IPv4 network host.
56
57       AF_INET6
58              The name argument points to a hexadecimal IPv6 address or a name
59              of an IPv6 network host.
60
61       The  flags argument specifies additional options.  More than one option
62       can be specified by bitwise OR-ing them together.  flags should be  set
63       to 0 if no options are desired.
64
65       AI_V4MAPPED
66              This  flag  is  used  with  AF_INET6 to request a query for IPv4
67              addresses instead of IPv6 addresses; the IPv4 addresses will  be
68              mapped to IPv6 addresses.
69
70       AI_ALL This  flag  is used with AI_V4MAPPED to request a query for both
71              IPv4 and IPv6 addresses.  Any IPv4 address found will be  mapped
72              to an IPv6 address.
73
74       AI_ADDRCONFIG
75              This  flag is used with AF_INET6 to further request that queries
76              for IPv6 addresses should not be made unless the system  has  at
77              least one IPv6 address assigned to a network interface, and that
78              queries for IPv4 addresses should not be made unless the  system
79              has  at  least one IPv4 address assigned to a network interface.
80              This flag may be used by itself or with the AI_V4MAPPED flag.
81
82       AI_DEFAULT
83              This flag is equivalent to (AI_ADDRCONFIG | AI_V4MAPPED).
84
85   getipnodebyaddr() arguments
86       The getipnodebyaddr() function looks up the name of the host whose net‐
87       work address is specified by the addr argument.  The af argument speci‐
88       fies one of the following values:
89
90       AF_INET
91              The addr argument points to a struct in_addr and len must be set
92              to sizeof(struct in_addr).
93
94       AF_INET6
95              The  addr  argument  points to a struct in6_addr and len must be
96              set to sizeof(struct in6_addr).
97

RETURN VALUE

99       NULL is returned if an error occurred, and error_num  will  contain  an
100       error code from the following list:
101
102       HOST_NOT_FOUND
103              The hostname or network address was not found.
104
105       NO_ADDRESS
106              The  domain  name server recognized the network address or name,
107              but no answer was returned.  This can happen if the network host
108              has  only  IPv4  addresses  and a request has been made for IPv6
109              information only, or vice versa.
110
111       NO_RECOVERY
112              The domain name server returned a permanent failure response.
113
114       TRY_AGAIN
115              The domain name server returned a  temporary  failure  response.
116              You might have better luck next time.
117
118       A  successful  query returns a pointer to a hostent structure that con‐
119       tains the following fields:
120
121       h_name This is the official name of this network host.
122
123       h_aliases
124              This is an array of pointers to unofficial aliases for the  same
125              host.  The array is terminated by a null pointer.
126
127       h_addrtype
128              This  is  a  copy  of  the  af  argument to getipnodebyname() or
129              getipnodebyaddr().  h_addrtype will always be AF_INET if the  af
130              argument was AF_INET.  h_addrtype will always be AF_INET6 if the
131              af argument was AF_INET6.
132
133       h_length
134              This field will be set to sizeof(struct in_addr)  if  h_addrtype
135              is  AF_INET,  and  to  sizeof(struct  in6_addr) if h_addrtype is
136              AF_INET6.
137
138       h_addr_list
139              This is an array of one or  more  pointers  to  network  address
140              structures  for  the network host.  The array is terminated by a
141              null pointer.
142

CONFORMING TO

144       RFC 2553.
145

NOTES

147       These functions were present  in  glibc  2.1.91-95,  but  were  removed
148       again.   Several UNIX-like systems support them, but all call them dep‐
149       recated.
150

SEE ALSO

152       getaddrinfo(3), getnameinfo(3), inet_ntop(3), inet_pton(3)
153

COLOPHON

155       This page is part of release 5.04 of the Linux  man-pages  project.   A
156       description  of  the project, information about reporting bugs, and the
157       latest    version    of    this    page,    can     be     found     at
158       https://www.kernel.org/doc/man-pages/.
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162Linux                             2017-09-15                GETIPNODEBYNAME(3)
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