1INET_NTOP(P) POSIX Programmer's Manual INET_NTOP(P)
2
6 inet_ntop, inet_pton - convert IPv4 and IPv6 addresses between binary
7 and text form
8
10 #include <arpa/inet.h>
11 const char *inet_ntop(int af, const void *restrict src,
13 char *restrict dst, socklen_t size);
14 int inet_pton(int af, const char *restrict src, void *restrict dst);
15
18 The inet_ntop() function shall convert a numeric address into a text
19 string suitable for presentation. The af argument shall specify the
20 family of the address. This can be AF_INET or AF_INET6. The src argu‐
21 ment points to a buffer holding an IPv4 address if the af argument is
22 AF_INET, or an IPv6 address if the af argument is AF_INET6; the
23 address must be in network byte order. The dst argument points to a
24 buffer where the function stores the resulting text string; it shall
25 not be NULL. The size argument specifies the size of this buffer, which
26 shall be large enough to hold the text string (INET_ADDRSTRLEN charac‐
27 ters for IPv4, INET6_ADDRSTRLEN characters for IPv6).
28 The inet_pton() function shall convert an address in its standard text
30 presentation form into its numeric binary form. The af argument shall
31 specify the family of the address. The AF_INET and AF_INET6 address
32 families shall be supported. The src argument points to the string
33 being passed in. The dst argument points to a buffer into which the
34 function stores the numeric address; this shall be large enough to hold
35 the numeric address (32 bits for AF_INET, 128 bits for AF_INET6).
36 If the af argument of inet_pton() is AF_INET, the src string shall be
38 in the standard IPv4 dotted-decimal form:
39 ddd.ddd.ddd.ddd
42 where "ddd" is a one to three digit decimal number between 0 and 255
44 (see inet_addr() ). The inet_pton() function does not accept other for‐
45 mats (such as the octal numbers, hexadecimal numbers, and fewer than
46 four numbers that inet_addr() accepts).
47 If the af argument of inet_pton() is AF_INET6, the src string shall be
49 in one of the following standard IPv6 text forms:
50 1. The preferred form is "x:x:x:x:x:x:x:x" , where the 'x' s are the
52 hexadecimal values of the eight 16-bit pieces of the address. Lead‐
53 ing zeros in individual fields can be omitted, but there shall be
54 at least one numeral in every field.
55 2. A string of contiguous zero fields in the preferred form can be
57 shown as "::" . The "::" can only appear once in an address.
58 Unspecified addresses ( "0:0:0:0:0:0:0:0" ) may be represented sim‐
59 ply as "::" .
60 3. A third form that is sometimes more convenient when dealing with a
62 mixed environment of IPv4 and IPv6 nodes is "x:x:x:x:x:x:d.d.d.d" ,
63 where the 'x' s are the hexadecimal values of the six high-order
64 16-bit pieces of the address, and the 'd' s are the decimal values
65 of the four low-order 8-bit pieces of the address (standard IPv4
66 representation).
67 Note: A more extensive description of the standard representations of
69 IPv6 addresses can be found in RFC 2373.
70
73 The inet_ntop() function shall return a pointer to the buffer contain‐
74 ing the text string if the conversion succeeds, and NULL otherwise, and
75 set errno to indicate the error.
76 The inet_pton() function shall return 1 if the conversion succeeds,
78 with the address pointed to by dst in network byte order. It shall
79 return 0 if the input is not a valid IPv4 dotted-decimal string or a
80 valid IPv6 address string, or -1 with errno set to [EAFNOSUPPORT] if
81 the af argument is unknown.
82
84 The inet_ntop() and inet_pton() functions shall fail if:
85 EAFNOSUPPORT
87 The af argument is invalid.
89 ENOSPC The size of the inet_ntop() result buffer is inadequate.
91 The following sections are informative.
94
96 None.
97
99 None.
100
102 None.
103
105 None.
106
108 The Base Definitions volume of IEEE Std 1003.1-2001, <arpa/inet.h>
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111 Portions of this text are reprinted and reproduced in electronic form
112 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
113 -- Portable Operating System Interface (POSIX), The Open Group Base
114 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
115 Electrical and Electronics Engineers, Inc and The Open Group. In the
116 event of any discrepancy between this version and the original IEEE and
117 The Open Group Standard, the original IEEE and The Open Group Standard
118 is the referee document. The original Standard can be obtained online
119 at http://www.opengroup.org/unix/online.html .
120IEEE/The Open Group 2003 INET_NTOP(P)