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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | STANDARDS | HISTORY | SEE ALSO | COLOPHON |
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getipnodebyname(3) Library Functions Manual getipnodebyname(3)
getipnodebyname, getipnodebyaddr, freehostent - get network
hostnames and addresses
Standard C library (libc, -lc)
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
[[deprecated]] struct hostent *getipnodebyname(const char *name, int af,
int flags, int *error_num);
[[deprecated]] struct hostent *getipnodebyaddr(const void addr[.len],
size_t len, int af,
int *error_num);
[[deprecated]] void freehostent(struct hostent *ip);
These functions are deprecated (and unavailable in glibc). Use
getaddrinfo(3) and getnameinfo(3) instead.
The getipnodebyname() and getipnodebyaddr() functions return the
names and addresses of a network host. These functions return a
pointer to the following structure:
struct hostent {
char *h_name;
char **h_aliases;
int h_addrtype;
int h_length;
char **h_addr_list;
};
These functions replace the gethostbyname(3) and gethostbyaddr(3)
functions, which could access only the IPv4 network address
family. The getipnodebyname() and getipnodebyaddr() functions
can access multiple network address families.
Unlike the gethostby functions, these functions return pointers
to dynamically allocated memory. The freehostent() function is
used to release the dynamically allocated memory after the caller
no longer needs the hostent structure.
getipnodebyname() arguments
The getipnodebyname() function looks up network addresses for the
host specified by the name argument. The af argument specifies
one of the following values:
AF_INET
The name argument points to a dotted-quad IPv4 address or
a name of an IPv4 network host.
AF_INET6
The name argument points to a hexadecimal IPv6 address or
a name of an IPv6 network host.
The flags argument specifies additional options. More than one
option can be specified by bitwise OR-ing them together. flags
should be set to 0 if no options are desired.
AI_V4MAPPED
This flag is used with AF_INET6 to request a query for
IPv4 addresses instead of IPv6 addresses; the IPv4
addresses will be mapped to IPv6 addresses.
AI_ALL This flag is used with AI_V4MAPPED to request a query for
both IPv4 and IPv6 addresses. Any IPv4 address found will
be mapped to an IPv6 address.
AI_ADDRCONFIG
This flag is used with AF_INET6 to further request that
queries for IPv6 addresses should not be made unless the
system has at least one IPv6 address assigned to a network
interface, and that queries for IPv4 addresses should not
be made unless the system has at least one IPv4 address
assigned to a network interface. This flag may be used by
itself or with the AI_V4MAPPED flag.
AI_DEFAULT
This flag is equivalent to (AI_ADDRCONFIG | AI_V4MAPPED).
getipnodebyaddr() arguments
The getipnodebyaddr() function looks up the name of the host
whose network address is specified by the addr argument. The af
argument specifies one of the following values:
AF_INET
The addr argument points to a struct in_addr and len must
be set to sizeof(struct in_addr).
AF_INET6
The addr argument points to a struct in6_addr and len must
be set to sizeof(struct in6_addr).
NULL is returned if an error occurred, and error_num will contain
an error code from the following list:
HOST_NOT_FOUND
The hostname or network address was not found.
NO_ADDRESS
The domain name server recognized the network address or
name, but no answer was returned. This can happen if the
network host has only IPv4 addresses and a request has
been made for IPv6 information only, or vice versa.
NO_RECOVERY
The domain name server returned a permanent failure
response.
TRY_AGAIN
The domain name server returned a temporary failure
response. You might have better luck next time.
A successful query returns a pointer to a hostent structure that
contains the following fields:
h_name This is the official name of this network host.
h_aliases
This is an array of pointers to unofficial aliases for the
same host. The array is terminated by a null pointer.
h_addrtype
This is a copy of the af argument to getipnodebyname() or
getipnodebyaddr(). h_addrtype will always be AF_INET if
the af argument was AF_INET. h_addrtype will always be
AF_INET6 if the af argument was AF_INET6.
h_length
This field will be set to sizeof(struct in_addr) if
h_addrtype is AF_INET, and to sizeof(struct in6_addr) if
h_addrtype is AF_INET6.
h_addr_list
This is an array of one or more pointers to network
address structures for the network host. The array is
terminated by a null pointer.
None.
RFC 2553.
Present in glibc 2.1.91-95, but removed again. Several UNIX-like
systems support them, but all call them deprecated.
getaddrinfo(3), getnameinfo(3), inet_ntop(3), inet_pton(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 getipnodebyname(3)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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