ref: b5bc6572b0a82c52ab04bcf25e1ed76700deb246
dir: /man/2/ip/
.TH IP 2
.SH NAME
IP \- Internet Protocol addresses and interfaces
.SH SYNOPSIS
.EX
include "ip.m";
ip := load IP IP->PATH;
IPaddr: import IP;
IPaddr: adt {
newv6: fn(nil: array of byte): IPaddr;
newv4: fn(nil: array of byte): IPaddr;
copy: fn(nil: self IPaddr): IPaddr;
eq: fn(nil: self IPaddr, v: IPaddr): int;
mask: fn(nil: self IPaddr, m: IPaddr): IPaddr;
isv4: fn(nil: self IPaddr): int;
ismulticast: fn(nil: self IPaddr): int;
isvalid: fn(nil: self IPaddr): int;
v4: fn(nil: self IPaddr): array of byte;
v6: fn(nil: self IPaddr): array of byte;
class: fn(nil: self IPaddr): int;
classmask: fn(nil: self IPaddr): IPaddr;
parse: fn(s: string): (int, IPaddr);
parsemask: fn(s: string): (int, IPaddr);
parsecidr: fn(s: string): (int, IPaddr, IPaddr);
text: fn(nil: self IPaddr): string;
masktext: fn(nil: self IPaddr): string;
};
v4bcast, v4allsys, v4allrouter, noaddr, allbits: IPaddr;
selfv6, selfv4: IPaddr;
v4prefix: array of byte;
Ifcaddr: adt {
ip: IPaddr; # local interface address
mask: IPaddr; # subnet mask
net: IPaddr; # ip & mask
preflt: big; # preferred life time
validlt: big; # valid life time
};
Ipifc: adt {
index: int; # /net/ipifc/N
dev: string; # bound device
addrs: list of ref Ifcaddr;
sendra: int; # !=0, send router adverts
recvra: int; # !=0, receive router adverts
mtu: int;
pktin: big; # packets in
pktout: big; # packets out
errin: big; # input errors
errout: big; # output errors
rp: IPv6rp; # IPv6 route advert parameters
};
IPv6rp: adt {
mflag: int;
oflag: int;
maxraint: int; # max route advert interval
minraint: int; # min route advert interval
linkmtu: int;
reachtime: int;
rxmitra: int;
ttl: int;
routerlt: int;
};
init: fn();
readipifc: fn(net: string, index: int): (list of ref Ipifc, string);
.EE
.SH DESCRIPTION
.B IP
provides data types and operations that manipulate Internet Protocol addresses,
and operations that convert between internal and textual address forms,
for both IPv4 and IPv6.
The textual forms are those defined by RFC2373.
Briefly, an IPv6 address is 16 bytes, represented textually as a sequence
of 8 colon-separated hexadecimal values ranging from
.B 0
to
.BR FFFF ,
except that any one sequence of zeroes can be replaced by
.BR :: .
IPv4 addresses are embedded in the IPv6 space with a prefix of either
.B 0:0:0:0:0:FFFF
(for addresses of `IPv4-mapped' nodes), or
.BR 0:0:0:0:0:0
(for `IPv4-compatible' IPv6 nodes).
See RFC2373 for the distinction.
For convenience in working with such addresses, the textual syntax
allows the last 4 bytes of an IPv6 address to be specified using a
restricted IPv4 syntax, allowing an address to end in four dot-separated decimal values
(for example,
.BR 0:0:0:0:0:FFFF:127.0.0.1
for the IPv4 loopback address).
The functions here also accept the common forms of IPv4 syntax with one or two values
omitted (eg,
.B 127.1
for the loopback address),
and accept IPv4 format for masks
(eg,
.BR 255.255.254.0 ).
.PP
.B Init
must be called once before using any value or function of the module.
.PP
An Internet address or network mask is represented by an
.B IPaddr
value.
It has the following operations:
.TP
.BI IPaddr.newv6( a )
Return an
.B IPaddr
representing the IPv6 address stored in
.I a
as an array of 16 bytes
.TP
.BI IPaddr.newv4( a )
Return an
.B IPaddr
representing the IPv4 address stored in
.I a
as an array of 4 bytes
.TP
.BI IPaddr.parse( s )
Return a tuple
.BI ( ok , ip ).
If
.I ok
is 0,
.I ip
is an
.B IPaddr
representing the address in textual format in the string
.IR s ,
which can be in either IPv4 or IPv6 syntax.
If
.I ok
is negative,
.I s
was invalid.
.TP
.BI IPaddr.parsemask( s )
.I S
is a text string defining a mask, in one of three forms:
.BI / nbits
where
.I nbits
is the number of leading one bits in the mask, ranging from 0 to 128;
an IPv4 mask (eg,
.BR 255.255.254.0 );
or an IPv6 mask.
Return a tuple
.BI ( ok , m )\fR.
If
.I ok
is 0,
.I m
is an
.B IPaddr
representing the mask given by
.IR s .
If
.I ok
is negative,
.I s
was invalid.
.TP
.BI IPaddr.parsecidr( s )
.I S
is an address-mask combination in Classless Inter-Domain Routing (CIDR) format:
.IB ip-address / prefix-length,
where
.I ip-address
is an address in any form accepted by
.B parse
above, and
.I prefix-length
is a decimal value giving the number of leftmost bits in
.I ip-address
that form the addressing prefix (ie, subnet prefix).
Return a tuple
.BI ( ok , ip , m\fR).
If
.I ok
is 0,
.I ip
and
.I m
are
.B IPaddr
values for the address and mask given by
.IR s .
If
.I ok
is negative,
.I s
is invalid.
.TP
.IB ip .copy()
Return a copy of the value
.I ip
.TP
.IB ip .eq( v )
Return true (non-zero) if
.I ip
represents the same address as
.IR v ;
return false (zero) otherwise.
.TP
.IB ip .mask( m )
Return the value
.BI ( ip & m ) ,
that is, address
.I ip
masked by
.I m
.TP
.IB ip .isv4()
Return true if
.I ip
is an IPv4 address; return false if
otherwise (it can only be used on a full IPv6 network)
.TP
.IB ip .v4()
Return the value of
.I ip
as a 4-byte array in IPv4 representation if it can be so represented;
if
.I ip
is not an IPv4 address, return nil.
.TP
.IB ip .v6()
Return the value of
.I ip
in IPv6 addressing format as an array of 16 bytes
.TP
.IB ip .class()
If
.I ip
is an IPv4 address, return its class (0 to 3); if it is an IPv6 address, return 6.
.TP
.IB ip .classmask()
If
.I ip
is an IPv4 address, return the mask associated with its class; if
.I ip
is an IPv6 address, return a mask that is all ones.
.TP
.IB ip .ismulticast()
Return true if
.I ip
is a multicast or broadcast address.
.TP
.IB ip .isvalid()
Return true if
.I ip
is not the zero address in either IPv4 or IPv6 address space
.TP
.IB ip .text()
Return a textual representation of the address
.I ip
in either IPv4 or IPv6 format as appropriate.
.TP
.IB ip .masktext()
Return a textual representation of the address
.I ip
as one of: an IPv4 mask;
.BI / n
where
.I n
is the number of leading 1 bits, as used in CIDR syntax; or
as a full IPv6 textual address.
The format used is appropriate to the structure of the value.
.PP
The module provides some predefined
.B IPaddr
values, mainly for common IPv4 addresses:
.B v4bcast
(broadcast address),
.B v4allsys
(all hosts multicast address),
.B v4allrouter
(all routers multicast address),
.B selfv4
(loopback in IPv4),
.B selfv6
(loopback in IPv6),
.B noaddr
(all zero address, used before a node has an address),
.B v4noaddr
(all zero address with IPv4 prefix),
and
.B allbits
(address of all 1 bits).
The 12-byte IPv6 prefix for IPv4 embedded addresses is provided in
the array of bytes
.BR v4prefix .
.PP
.B Readipifc
returns a list of the host's IP interfaces
and the attributes and addresses of each,
read from the interface status files in
.BR /net/ipifc .
On an error, the string in the returned tuple contains a diagnostic and the list is nil.
Each interface is represented by an
.B Ipifc
value, which contains a list of local interface addresses,
.BR addrs .
Each local address is represented by an
.B Iplifc
value in that list.
.SH FILES
.TF /net/ipifc/N/status
.TP
.B /net/ipifc
directory of IP interfaces
.TP
.BI /net/ipifc/ n /status
status and addresses of interface
.I n
.SH SOURCE
.B /appl/lib/ip.b
.SH SEE ALSO
.IR ether (2),
.IR ip (3)
.SH BUGS
.B Readipifc
is currently only usable in native Inferno.
That will change shortly.