getipnodebyname(3) - Linux manual page (original) (raw)

getipnodebyname(3) Library Functions Manual getipnodebyname(3)

NAME top

   getipnodebyname, getipnodebyaddr, freehostent - get network
   hostnames and addresses

LIBRARY top

   Standard C library (_libc_, _-lc_)

SYNOPSIS top

   **#include <sys/types.h>**
   **#include <sys/socket.h>**
   **#include <netdb.h>**

   **[[deprecated]] struct hostent *getipnodebyname(const char ***_name_**, int** _af_**,**
                                               **int** _flags_**, int ***_errornum_**);**
   **[[deprecated]] struct hostent *getipnodebyaddr(const void** _addr_**[.**_size_**],**
                                               **size_t** _size_**, int** _af_**,**
                                               **int ***_errornum_**);**
   **[[deprecated]] void freehostent(struct hostent ***_ip_**);**

DESCRIPTION top

   These functions are deprecated (and unavailable in glibc).  Use
   [getaddrinfo(3)](../man3/getaddrinfo.3.html) and [getnameinfo(3)](../man3/getnameinfo.3.html) 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)](../man3/gethostbyname.3.html) and [gethostbyaddr(3)](../man3/gethostbyaddr.3.html)
   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 inaddr_ and _size_ must
          be set to _sizeof(struct inaddr)_.

   **AF_INET6**
          The _addr_ argument points to a _struct in6addr_ and _size_ must
          be set to _sizeof(struct in6addr)_.

RETURN VALUE top

   NULL is returned if an error occurred, and _errornum_ 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:

   _hname_ This is the official name of this network host.

   _haliases_
          This is an array of pointers to unofficial aliases for the
          same host.  The array is terminated by a null pointer.

   _haddrtype_
          This is a copy of the _af_ argument to **getipnodebyname**() or
          **getipnodebyaddr**().  _haddrtype_ will always be **AF_INET** if
          the _af_ argument was **AF_INET**.  _haddrtype_ will always be
          **AF_INET6** if the _af_ argument was **AF_INET6**.

   _hlength_
          This field will be set to _sizeof(struct inaddr)_ if
          _haddrtype_ is **AF_INET**, and to _sizeof(struct in6addr)_ if
          _haddrtype_ is **AF_INET6**.

   _haddrlist_
          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.

STANDARDS top

   None.

HISTORY top

   RFC 2553.

   Present in glibc 2.1.91-95, but removed again.  Several UNIX-like
   systems support them, but all call them deprecated.

COLOPHON top

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Linux man-pages 6.10 2024-11-17 getipnodebyname(3)