inet_aton inet_addr inet_network inet_ntoa inet_ntoa_r inet_ntop inet_pton inet_makeaddr inet_lnaof inet_netof - Internet address manipulation routines
Lb libc
The
inet_pton ();
function converts a presentation format address (that is, printable form
as held in a character string) to network format (usually a
struct in_addr
or some other internal binary representation, in network byte order).
It returns 1 if the address was valid for the specified address family, or
0 if the address was not parseable in the specified address family, or -1
if some system error occurred (in which case
errno
will have been set).
This function is presently valid for
AF_INET
and
AF_INET6
The
inet_aton ();
routine interprets the specified character string as an Internet address,
placing the address into the structure provided.
It returns 1 if the string was successfully interpreted,
or 0 if the string is invalid.
The
inet_addr ();
and
inet_network ();
functions return numbers suitable for use
as Internet addresses and Internet network
numbers, respectively.
The function
inet_ntop ();
converts an address
Fa *src
from network format
(usually a
struct in_addr
or some other binary form, in network byte order) to presentation format
(suitable for external display purposes).
The
Fa size
argument specifies the size, in bytes, of the buffer
Fa *dst .
INET_ADDRSTRLEN
and
INET6_ADDRSTRLEN
define the maximum size required to convert an address of the respective
type.
It returns NULL if a system error occurs (in which case,
errno
will have been set), or it returns a pointer to the destination string.
This function is presently valid for
AF_INET
and
AF_INET6
The routine
inet_ntoa ();
takes an Internet address and returns an
ASCII
string representing the address in
`.'
notation.
The routine
inet_ntoa_r ();
is the reentrant version of
inet_ntoa (.);
The routine
inet_makeaddr ();
takes an Internet network number and a local
network address and constructs an Internet address
from it.
The routines
inet_netof ();
and
inet_lnaof ();
break apart Internet host addresses, returning
the network number and local network address part,
respectively.
All Internet addresses are returned in network order (bytes ordered from left to right). All network numbers and local address parts are returned as machine byte order integer values.
a.b.c.d a.b.c a.b a
When four parts are specified, each is interpreted as a byte of data and assigned, from left to right, to the four bytes of an Internet address. Note that when an Internet address is viewed as a 32-bit integer quantity on the VAX the bytes referred to above appear as ``d.c.b.a '' That is, VAX bytes are ordered from right to left.
When a three part address is specified, the last part is interpreted as a 16-bit quantity and placed in the right-most two bytes of the network address. This makes the three part address format convenient for specifying Class B network addresses as ``128.net.host ''
When a two part address is supplied, the last part is interpreted as a 24-bit quantity and placed in the right most three bytes of the network address. This makes the two part address format convenient for specifying Class A network addresses as ``net.host ''
When only one part is given, the value is stored directly in the network address without any byte rearrangement.
All numbers supplied as ``parts'' in a `.' notation may be decimal, octal, or hexadecimal, as specified in the C language (i.e., a leading 0x or 0X implies hexadecimal; otherwise, a leading 0 implies octal; otherwise, the number is interpreted as decimal).
The
inet_addr ();
function should return a
Fa struct in_addr .
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