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       inet_pton - convert IPv4 and IPv6 addresses from text to binary form


       #include <arpa/inet.h>

       int inet_pton(int af, const char *src, void *dst);


       This  function converts the character string src into a network address
       structure in the af address family, then  copies  the  network  address
       structure to dst.  The af argument must be either AF_INET or AF_INET6.

       The following address families are currently supported:

              src  points  to  a  character  string containing an IPv4 network
              address in dotted-decimal format, "ddd.ddd.ddd.ddd",  where  ddd
              is a decimal number of up to three digits in the range 0 to 255.
              The address is converted to a struct in_addr and copied to  dst,
              which must be sizeof(struct in_addr) (4) bytes (32 bits) long.

              src  points  to  a  character  string containing an IPv6 network
              address.  The address is converted  to  a  struct  in6_addr  and
              copied  to dst, which must be sizeof(struct in6_addr) (16) bytes
              (128 bits) long.  The allowed formats for IPv6 addresses  follow
              these rules:

              1. The  preferred format is x:x:x:x:x:x:x:x.  This form consists
                 of eight hexadecimal  numbers,  each  of  which  expresses  a
                 16-bit value (i.e., each x can be up to 4 hex digits).

              2. A  series  of  contiguous zero values in the preferred format
                 can be abbreviated to ::.  Only one instance of :: can  occur
                 in   an   address.    For   example,   the  loopback  address
                 0:0:0:0:0:0:0:1 can be  abbreviated  as  ::1.   The  wildcard
                 address, consisting of all zeros, can be written as ::.

              3. An alternate format is useful for expressing IPv4-mapped IPv6
                 addresses.  This  form  is  written  as  x:x:x:x:x:x:d.d.d.d,
                 where  the  six leading xs are hexadecimal values that define
                 the six most-significant 16-bit pieces of the address  (i.e.,
                 96  bits),  and  the  ds  express  a  value in dotted-decimal
                 notation that defines the least significant 32  bits  of  the
                 address.     An    example    of    such    an   address   is

              See RFC 2373 for further details on the representation  of  IPv6


       inet_pton()  returns  1  on  success  (network address was successfully
       converted).  0 is returned if src does not contain a  character  string
       representing  a  valid network address in the specified address family.
       If af does not contain a valid address family, -1 is returned and errno
       is set to EAFNOSUPPORT.


       For   an   explanation   of   the  terms  used  in  this  section,  see

       │InterfaceAttributeValue          │
       │inet_pton() │ Thread safety │ MT-Safe locale │


       POSIX.1-2001, POSIX.1-2008.


       Unlike  inet_aton(3)  and  inet_addr(3),  inet_pton()   supports   IPv6
       addresses.   On the other hand, inet_pton() accepts only IPv4 addresses
       in dotted-decimal notation, whereas inet_aton(3) and inet_addr(3) allow
       the  more  general  numbers-and-dots  notation  (hexadecimal  and octal
       number formats, and formats that don't require all  four  bytes  to  be
       explicitly   written).    For  an  interface  that  handles  both  IPv6
       addresses,  and  IPv4  addresses  in  numbers-and-dots  notation,   see


       AF_INET6  does  not  recognize IPv4 addresses.  An explicit IPv4-mapped
       IPv6 address must be supplied in src instead.


       The program below demonstrates the use of inet_pton() and inet_ntop(3).
       Here are some example runs:

           $ ./a.out i6 0:0:0:0:0:0:0:0
           $ ./a.out i6 1:0:0:0:0:0:0:8
           $ ./a.out i6 0:0:0:0:0:FFFF:

   Program source

       #include <arpa/inet.h>
       #include <stdio.h>
       #include <stdlib.h>
       #include <string.h>

       main(int argc, char *argv[])
           unsigned char buf[sizeof(struct in6_addr)];
           int domain, s;
           char str[INET6_ADDRSTRLEN];

           if (argc != 3) {
               fprintf(stderr, "Usage: %s {i4|i6|<num>} string\n", argv[0]);

           domain = (strcmp(argv[1], "i4") == 0) ? AF_INET :
                    (strcmp(argv[1], "i6") == 0) ? AF_INET6 : atoi(argv[1]);

           s = inet_pton(domain, argv[2], buf);
           if (s <= 0) {
               if (s == 0)
                   fprintf(stderr, "Not in presentation format");

           if (inet_ntop(domain, buf, str, INET6_ADDRSTRLEN) == NULL) {

           printf("%s\n", str);



       getaddrinfo(3), inet(3), inet_ntop(3)


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