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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 zeroes, 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.




       Unlike  inet_aton(3)  and  inet_addr(3),  inet_pton()   supports   IPv6
       addresses.   On the other hand, inet_pton() only accepts 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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