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INET_PTON(3)               Linux Programmer's ManualINET_PTON(3)NAME       inet_pton - convert IPv4 and IPv6 addresses from text to binary formSYNOPSIS       #include <arpa/inet.h>       int inet_pton(int af, const char *src, void *dst);DESCRIPTION       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.       dst is written in network byte order.       The following address families are currently supported:       AF_INET              src points to a character string containing an IPv4 network  ad-              dress  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.       AF_INET6              src points to a character string containing an IPv6 network  ad-              dress.  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 ad-                 dress, 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  nota-                 tion  that  defines  the least significant 32 bits of the ad-                 dress.     An    example    of    such    an    address    is                 ::FFFF:204.152.189.116.              See  RFC  2373 for further details on the representation of IPv6              addresses.RETURN VALUE       inet_pton() returns 1 on success (network address was successfully con-       verted).  0 is returned if src does not contain a character string rep-       resenting 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.ATTRIBUTES       For an  explanation  of  the  terms  used  in  this  section,  see  at-tributes(7).       +------------+---------------+----------------+       |Interface   | Attribute     | Value          |       +------------+---------------+----------------+       |inet_pton() | Thread safety | MT-Safe locale |       +------------+---------------+----------------+CONFORMING TO       POSIX.1-2001, POSIX.1-2008.NOTES       Unlikeinet_aton(3)  andinet_addr(3),  inet_pton() supports IPv6 ad-       dresses.  On the other hand, inet_pton() accepts only IPv4 addresses in       dotted-decimal  notation,  whereasinet_aton(3) andinet_addr(3) allow       the more general numbers-and-dots notation (hexadecimal and octal  num-       ber  formats,  and  formats that don't require all four bytes to be ex-       plicitly written).  For an interface that handles both IPv6  addresses,       and IPv4 addresses in numbers-and-dots notation, seegetaddrinfo(3).BUGS       AF_INET6  does  not  recognize IPv4 addresses.  An explicit IPv4-mapped       IPv6 address must be supplied in src instead.EXAMPLES       The program below demonstrates the use of inet_pton() andinet_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           1::8           $ ./a.out i6 0:0:0:0:0:FFFF:204.152.189.116           ::ffff:204.152.189.116   Program source       #include <arpa/inet.h>       #include <stdio.h>       #include <stdlib.h>       #include <string.h>       int       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]);               exit(EXIT_FAILURE);           }           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");               else                   perror("inet_pton");               exit(EXIT_FAILURE);           }           if (inet_ntop(domain, buf, str, INET6_ADDRSTRLEN) == NULL) {               perror("inet_ntop");               exit(EXIT_FAILURE);           }           printf("%s\n", str);           exit(EXIT_SUCCESS);       }SEE ALSOgetaddrinfo(3),inet(3),inet_ntop(3)COLOPHON       This  page  is  part of release 5.10 of the Linux man-pages project.  A       description of the project, information about reporting bugs,  and  the       latest     version     of     this    page,    can    be    found    at       https://www.kernel.org/doc/man-pages/.Linux                             2020-06-09INET_PTON(3)