man3/inet_ntop.3

   1 .\" Copyright 2000 Sam Varshavchik <mrsam@courier-mta.com>
   2 .\"
   3 .\" %%%LICENSE_START(VERBATIM)
   4 .\" Permission is granted to make and distribute verbatim copies of this
   5 .\" manual provided the copyright notice and this permission notice are
   6 .\" preserved on all copies.
   7 .\"
   8 .\" Permission is granted to copy and distribute modified versions of this
   9 .\" manual under the conditions for verbatim copying, provided that the
  10 .\" entire resulting derived work is distributed under the terms of a
  11 .\" permission notice identical to this one.
  12 .\"
  13 .\" Since the Linux kernel and libraries are constantly changing, this
  14 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
  15 .\" responsibility for errors or omissions, or for damages resulting from
  16 .\" the use of the information contained herein.  The author(s) may not
  17 .\" have taken the same level of care in the production of this manual,
  18 .\" which is licensed free of charge, as they might when working
  19 .\" professionally.
  20 .\"
  21 .\" Formatted or processed versions of this manual, if unaccompanied by
  22 .\" the source, must acknowledge the copyright and authors of this work.
  23 .\" %%%LICENSE_END
  24 .\"
  25 .\" References: RFC 2553
  26 .TH INET_NTOP 3 2015-08-08 "Linux" "Linux Programmer's Manual"
  27 .SH NAME
  28 inet_ntop \- convert IPv4 and IPv6 addresses from binary to text form
  29 .SH SYNOPSIS
  30 .nf
  31 .B #include <arpa/inet.h>
  32 .sp
  33 .BI "const char *inet_ntop(int " "af" ", const void *" "src" ,
  34 .BI "                      char *" "dst" ", socklen_t " "size" );
  35 .fi
  36 .SH DESCRIPTION
  37 This function converts the network address structure
  38 .I src
  39 in the
  40 .I af
  41 address family into a character string.
  42 The resulting string is copied to the buffer pointed to by
  43 .IR dst ,
  44 which must be a non-null pointer.
  45 The caller specifies the number of bytes available in this buffer in
  46 the argument
  47 .IR size .
  48 .PP
  49 .BR inet_ntop ()
  50 extends the
  51 .BR inet_ntoa (3)
  52 function to support multiple address families,
  53 .BR inet_ntoa (3)
  54 is now considered to be deprecated in favor of
  55 .BR inet_ntop ().
  56 The following address families are currently supported:
  57 .TP
  58 .B AF_INET
  59 .I src
  60 points to a
  61 .I struct in_addr
  62 (in network byte order)
  63 which is converted to an IPv4 network address in
  64 the dotted-decimal format, "\fIddd.ddd.ddd.ddd\fP".
  65 The buffer
  66 .I dst
  67 must be at least
  68 .B INET_ADDRSTRLEN
  69 bytes long.
  70 .TP
  71 .B AF_INET6
  72 .I src
  73 points to a
  74 .I struct in6_addr
  75 (in network byte order)
  76 which is converted to a representation of this address in the
  77 most appropriate IPv6 network address format for this address.
  78 The buffer
  79 .I dst
  80 must be at least
  81 .B INET6_ADDRSTRLEN
  82 bytes long.
  83 .SH RETURN VALUE
  84 On success,
  85 .BR inet_ntop ()
  86 returns a non-null pointer to
  87 .IR dst .
  88 NULL is returned if there was an error, with
  89 .I errno
  90 set to indicate the error.
  91 .SH ERRORS
  92 .TP
  93 .B EAFNOSUPPORT
  94 .I af
  95 was not a valid address family.
  96 .TP
  97 .B ENOSPC
  98 The converted address string would exceed the size given by
  99 .IR size .
 100 .SH ATTRIBUTES
 101 For an explanation of the terms used in this section, see
 102 .BR attributes (7).
 103 .TS
 104 allbox;
 105 lb lb lb
 106 l l l.
 107 Interface       Attribute       Value
 108 T{
 109 .BR inet_ntop ()
 110 T}      Thread safety   MT-Safe locale
 111 .TE
 112
 113 .SH CONFORMING TO
 114 POSIX.1-2001, POSIX.1-2008.
 115 Note that RFC\ 2553 defines a prototype where the last argument
 116 .I size
 117 is of type
 118 .IR size_t .
 119 Many systems follow RFC\ 2553.
 120 Glibc 2.0 and 2.1 have
 121 .IR size_t ,
 122 but 2.2 and later have
 123 .IR socklen_t .
 124 .\" 2.1.3: size_t, 2.1.91: socklen_t
 125 .SH BUGS
 126 .B AF_INET6
 127 converts IPv4-mapped IPv6 addresses into an IPv6 format.
 128 .SH EXAMPLE
 129 See
 130 .BR inet_pton (3).
 131 .SH SEE ALSO
 132 .BR getnameinfo (3),
 133 .BR inet (3),
 134 .BR inet_pton (3)