icmp6 - Internet Control Message Protocol for IPv6
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/icmp6.h>
int
socket(AF_INET6, SOCK_RAW, proto);
ICMPv6 is the error and control message protocol used by
IPv6 and the Internet
protocol family. It may be accessed through a ``raw
socket'' for
network monitoring and diagnostic functions. The proto parameter to the
socket call to create an ICMPv6 socket is obtained from
getprotobyname(3), or you can use IPPROTO_ICMPV6. ICMPv6
sockets are
connectionless, and are normally used with the sendto(2) and
recvfrom(2)
calls, though the connect(2) call may also be used to fix
the destination
for future packets (in which case the read(2) or recv(2) and
write(2) or
send(2) system calls may be used).
Outgoing packets automatically have an IPv6 header prepended
to them
(based on the destination address). The ICMPv6 pseudo-header checksum
field (icmp6_cksum) is filled automatically by the kernel.
Incoming
packets are received without the IPv6 header or IPv6 extension headers.
Notice that this behavior is opposite to that of IPv4 raw
sockets and
ICMPv4 sockets.
ICMPv6 type/code filter
Each ICMPv6 raw socket has an associated filter whose
datatype is defined
as struct icmp6_filter;
This structure, along with the macros and constants defined
later in this
section, are defined as a result of including the
<netinet/icmp6.h> header.
The current filter is fetched and stored using getsockopt(2)
and
setsockopt(2) with a level of IPPROTO_ICMPV6 and an option
name of
ICMP6_FILTER.
Six macros operate on an icmp6_filter structure:
void ICMP6_FILTER_SETPASSALL(struct icmp6_filter *)
void ICMP6_FILTER_SETBLOCKALL(struct icmp6_filter *)
void ICMP6_FILTER_SETPASS(int, struct icmp6_filter *)
void ICMP6_FILTER_SETBLOCK(int, struct icmp6_filter *)
int ICMP6_FILTER_WILLPASS(int, const struct
icmp6_filter *)
int ICMP6_FILTER_WILLBLOCK(int, const struct
icmp6_filter *)
The first argument to the last four macros (an integer) is
an ICMPv6 message
type, between 0 and 255. The pointer argument to all
six macros is
a pointer to a filter that is modified by the first four
macros examined
by the last two macros.
The first two macros, SETPASSALL and SETBLOCKALL, specify
that all ICMPv6
messages are passed to the application or that all ICMPv6
messages are
blocked from being passed to the application.
The next two macros, SETPASS and SETBLOCK, specify that messages of a
given ICMPv6 type should be passed to the application or not
passed to
the application (blocked).
The final two macros, WILLPASS and WILLBLOCK, return true or
false depending
on whether the specified message type is passed to
the application
or blocked from being passed to the application by the
filter pointed
to by the second argument.
When an ICMPv6 raw socket is created, it will by default
pass all ICMPv6
message types to the application.
For further discussions see RFC 2292.
A socket operation may fail with one of the following errors
returned:
[EISCONN] when trying to establish a connection on a
socket which
already has one, or when trying to send a
datagram with
the destination address specified and the
socket is already
connected.
[ENOTCONN] when trying to send a datagram, but no destination address
is specified, and the socket hasn't
been connected.
[ENOBUFS] when the system runs out of memory for an
internal data
structure.
[EADDRNOTAVAIL] when an attempt is made to create a socket
with a network
address for which no network interface
exists.
recv(2), send(2), inet6(4), ip6(4), netintro(4)
W. Stevens and M. Thomas, Advanced Sockets API for IPv6, RFC
2292,
February 1998.
A. Conta and S. Deering, Internet Control Message Protocol
(ICMPv6) for
the Internet Protocol Version 6 (IPv6) Specification, RFC
2463, December
1998.
The implementation is based on KAME stack (which is a descendant of WIDE
hydrangea IPv6 stack kit).
Part of the document was shamelessly copied from RFC 2292.
OpenBSD 3.6 December 17, 1999
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