689 lines
21 KiB
Groff
689 lines
21 KiB
Groff
.\" $KAME: ip6.4,v 1.23 2005/01/11 05:56:25 itojun Exp $
|
|
.\" $OpenBSD: ip6.4,v 1.21 2005/01/06 03:50:46 itojun Exp $
|
|
.\"
|
|
.\" Copyright (c) 1983, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd September 29, 2006
|
|
.Dt IP6 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm ip6
|
|
.Nd Internet Protocol version 6 (IPv6) network layer
|
|
.Sh SYNOPSIS
|
|
.In sys/socket.h
|
|
.In netinet/in.h
|
|
.Ft int
|
|
.Fn socket AF_INET6 SOCK_RAW proto
|
|
.Sh DESCRIPTION
|
|
The IPv6 network layer is used by the IPv6 protocol family for
|
|
transporting data.
|
|
IPv6 packets contain an IPv6 header that is not provided as part of the
|
|
payload contents when passed to an application.
|
|
IPv6 header options affect the behavior of this protocol and may be used
|
|
by high-level protocols (such as the
|
|
.Xr tcp 4
|
|
and
|
|
.Xr udp 4
|
|
protocols) as well as directly by
|
|
.Dq raw sockets ,
|
|
which process IPv6 messages at a lower-level and may be useful for
|
|
developing new protocols and special-purpose applications.
|
|
.Ss Header
|
|
All IPv6 packets begin with an IPv6 header.
|
|
When data received by the kernel are passed to the application, this
|
|
header is not included in buffer, even when raw sockets are being used.
|
|
Likewise, when data are sent to the kernel for transmit from the
|
|
application, the buffer is not examined for an IPv6 header:
|
|
the kernel always constructs the header.
|
|
To directly access IPv6 headers from received packets and specify them
|
|
as part of the buffer passed to the kernel, link-level access
|
|
.Po
|
|
.Xr bpf 4 ,
|
|
for example
|
|
.Pc
|
|
must instead be utilized.
|
|
.Pp
|
|
The header has the following definition:
|
|
.Bd -literal -offset indent
|
|
struct ip6_hdr {
|
|
union {
|
|
struct ip6_hdrctl {
|
|
u_int32_t ip6_un1_flow; /* 20 bits of flow ID */
|
|
u_int16_t ip6_un1_plen; /* payload length */
|
|
u_int8_t ip6_un1_nxt; /* next header */
|
|
u_int8_t ip6_un1_hlim; /* hop limit */
|
|
} ip6_un1;
|
|
u_int8_t ip6_un2_vfc; /* version and class */
|
|
} ip6_ctlun;
|
|
struct in6_addr ip6_src; /* source address */
|
|
struct in6_addr ip6_dst; /* destination address */
|
|
} __packed;
|
|
|
|
#define ip6_vfc ip6_ctlun.ip6_un2_vfc
|
|
#define ip6_flow ip6_ctlun.ip6_un1.ip6_un1_flow
|
|
#define ip6_plen ip6_ctlun.ip6_un1.ip6_un1_plen
|
|
#define ip6_nxt ip6_ctlun.ip6_un1.ip6_un1_nxt
|
|
#define ip6_hlim ip6_ctlun.ip6_un1.ip6_un1_hlim
|
|
#define ip6_hops ip6_ctlun.ip6_un1.ip6_un1_hlim
|
|
.Ed
|
|
.Pp
|
|
All fields are in network-byte order.
|
|
Any options specified (see
|
|
.Sx Options
|
|
below) must also be specified in network-byte order.
|
|
.Pp
|
|
.Va ip6_flow
|
|
specifies the flow ID.
|
|
.Va ip6_plen
|
|
specifies the payload length.
|
|
.Va ip6_nxt
|
|
specifies the type of the next header.
|
|
.Va ip6_hlim
|
|
specifies the hop limit.
|
|
.Pp
|
|
The top 4 bits of
|
|
.Va ip6_vfc
|
|
specify the class and the bottom 4 bits specify the version.
|
|
.Pp
|
|
.Va ip6_src
|
|
and
|
|
.Va ip6_dst
|
|
specify the source and destination addresses.
|
|
.Pp
|
|
The IPv6 header may be followed by any number of extension headers that start
|
|
with the following generic definition:
|
|
.Bd -literal -offset indent
|
|
struct ip6_ext {
|
|
u_int8_t ip6e_nxt;
|
|
u_int8_t ip6e_len;
|
|
} __packed;
|
|
.Ed
|
|
.Ss Options
|
|
IPv6 allows header options on packets to manipulate the behavior of the
|
|
protocol.
|
|
These options and other control requests are accessed with the
|
|
.Xr getsockopt 2
|
|
and
|
|
.Xr setsockopt 2
|
|
system calls at level
|
|
.Dv IPPROTO_IPV6
|
|
and by using ancillary data in
|
|
.Xr recvmsg 2
|
|
and
|
|
.Xr sendmsg 2 .
|
|
They can be used to access most of the fields in the IPv6 header and
|
|
extension headers.
|
|
.Pp
|
|
The following socket options are supported:
|
|
.Bl -tag -width Ds
|
|
.\" .It Dv IPV6_OPTIONS
|
|
.It Dv IPV6_UNICAST_HOPS Fa "int *"
|
|
Get or set the default hop limit header field for outgoing unicast
|
|
datagrams sent on this socket.
|
|
A value of \-1 resets to the default value.
|
|
.\" .It Dv IPV6_RECVOPTS Fa "int *"
|
|
.\" Get or set the status of whether all header options will be
|
|
.\" delivered along with the datagram when it is received.
|
|
.\" .It Dv IPV6_RECVRETOPTS Fa "int *"
|
|
.\" Get or set the status of whether header options will be delivered
|
|
.\" for reply.
|
|
.\" .It Dv IPV6_RECVDSTADDR Fa "int *"
|
|
.\" Get or set the status of whether datagrams are received with
|
|
.\" destination addresses.
|
|
.\" .It Dv IPV6_RETOPTS
|
|
.\" Get or set IPv6 options.
|
|
.It Dv IPV6_MULTICAST_IF Fa "u_int *"
|
|
Get or set the interface from which multicast packets will be sent.
|
|
For hosts with multiple interfaces, each multicast transmission is sent
|
|
from the primary network interface.
|
|
The interface is specified as its index as provided by
|
|
.Xr if_nametoindex 3 .
|
|
A value of zero specifies the default interface.
|
|
.It Dv IPV6_MULTICAST_HOPS Fa "int *"
|
|
Get or set the default hop limit header field for outgoing multicast
|
|
datagrams sent on this socket.
|
|
This option controls the scope of multicast datagram transmissions.
|
|
.Pp
|
|
Datagrams with a hop limit of 1 are not forwarded beyond the local
|
|
network.
|
|
Multicast datagrams with a hop limit of zero will not be transmitted on
|
|
any network but may be delivered locally if the sending host belongs to
|
|
the destination group and if multicast loopback (see below) has not been
|
|
disabled on the sending socket.
|
|
Multicast datagrams with a hop limit greater than 1 may be forwarded to
|
|
the other networks if a multicast router (such as
|
|
.Xr mrouted 8 Pq Pa ports/net/mrouted )
|
|
is attached to the local network.
|
|
.It Dv IPV6_MULTICAST_LOOP Fa "u_int *"
|
|
Get or set the status of whether multicast datagrams will be looped back
|
|
for local delivery when a multicast datagram is sent to a group to which
|
|
the sending host belongs.
|
|
.Pp
|
|
This option improves performance for applications that may have no more
|
|
than one instance on a single host (such as a router daemon) by
|
|
eliminating the overhead of receiving their own transmissions.
|
|
It should generally not be used by applications for which there may be
|
|
more than one instance on a single host (such as a conferencing program)
|
|
or for which the sender does not belong to the destination group
|
|
(such as a time-querying program).
|
|
.Pp
|
|
A multicast datagram sent with an initial hop limit greater than 1 may
|
|
be delivered to the sending host on a different interface from that on
|
|
which it was sent if the host belongs to the destination group on that
|
|
other interface.
|
|
The multicast loopback control option has no effect on such delivery.
|
|
.It Dv IPV6_JOIN_GROUP Fa "struct ipv6_mreq *"
|
|
Join a multicast group.
|
|
A host must become a member of a multicast group before it can receive
|
|
datagrams sent to the group.
|
|
.Bd -literal
|
|
struct ipv6_mreq {
|
|
struct in6_addr ipv6mr_multiaddr;
|
|
unsigned int ipv6mr_interface;
|
|
};
|
|
.Ed
|
|
.Pp
|
|
.Va ipv6mr_interface
|
|
may be set to zeroes to choose the default multicast interface or to the
|
|
index of a particular multicast-capable interface if the host is
|
|
multihomed.
|
|
Membership is associated with a single interface; programs running on
|
|
multihomed hosts may need to join the same group on more than one
|
|
interface.
|
|
.Pp
|
|
If the multicast address is unspecified (i.e., all zeroes), messages
|
|
from all multicast addresses will be accepted by this group.
|
|
Note that setting to this value requires superuser privileges.
|
|
.It Dv IPV6_LEAVE_GROUP Fa "struct ipv6_mreq *"
|
|
Drop membership from the associated multicast group.
|
|
Memberships are automatically dropped when the socket is closed or when
|
|
the process exits.
|
|
.It Dv IPV6_PORTRANGE Fa "int *"
|
|
Get or set the allocation policy of ephemeral ports for when the kernel
|
|
automatically binds a local address to this socket.
|
|
The following values are available:
|
|
.Pp
|
|
.Bl -tag -width IPV6_PORTRANGE_DEFAULT -compact
|
|
.It Dv IPV6_PORTRANGE_DEFAULT
|
|
Use the regular range of non-reserved ports (varies, see
|
|
.Xr sysctl 8 ) .
|
|
.It Dv IPV6_PORTRANGE_HIGH
|
|
Use a high range (varies, see
|
|
.Xr sysctl 8 ) .
|
|
.It Dv IPV6_PORTRANGE_LOW
|
|
Use a low, reserved range (600\-1023).
|
|
.El
|
|
.It Dv IPV6_PKTINFO Fa "int *"
|
|
Get or set whether additional information about subsequent packets will
|
|
be provided as ancillary data along with the payload in subsequent
|
|
.Xr recvmsg 2
|
|
calls.
|
|
The information is stored in the following structure in the ancillary
|
|
data returned:
|
|
.Bd -literal
|
|
struct in6_pktinfo {
|
|
struct in6_addr ipi6_addr; /* src/dst IPv6 address */
|
|
unsigned int ipi6_ifindex; /* send/recv if index */
|
|
};
|
|
.Ed
|
|
.It Dv IPV6_HOPLIMIT Fa "int *"
|
|
Get or set whether the hop limit header field from subsequent packets
|
|
will be provided as ancillary data along with the payload in subsequent
|
|
.Xr recvmsg 2
|
|
calls.
|
|
The value is stored as an
|
|
.Vt int
|
|
in the ancillary data returned.
|
|
.\" .It Dv IPV6_NEXTHOP Fa "int *"
|
|
.\" Get or set whether the address of the next hop for subsequent
|
|
.\" packets will be provided as ancillary data along with the payload in
|
|
.\" subsequent
|
|
.\" .Xr recvmsg 2
|
|
.\" calls.
|
|
.\" The option is stored as a
|
|
.\" .Vt sockaddr
|
|
.\" structure in the ancillary data returned.
|
|
.\" .Pp
|
|
.\" This option requires superuser privileges.
|
|
.It Dv IPV6_HOPOPTS Fa "int *"
|
|
Get or set whether the hop-by-hop options from subsequent packets will be
|
|
provided as ancillary data along with the payload in subsequent
|
|
.Xr recvmsg 2
|
|
calls.
|
|
The option is stored in the following structure in the ancillary data
|
|
returned:
|
|
.Bd -literal
|
|
struct ip6_hbh {
|
|
u_int8_t ip6h_nxt; /* next header */
|
|
u_int8_t ip6h_len; /* length in units of 8 octets */
|
|
/* followed by options */
|
|
} __packed;
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fn inet6_option_space
|
|
routine and family of routines may be used to manipulate this data.
|
|
.Pp
|
|
This option requires superuser privileges.
|
|
.It Dv IPV6_DSTOPTS Fa "int *"
|
|
Get or set whether the destination options from subsequent packets will
|
|
be provided as ancillary data along with the payload in subsequent
|
|
.Xr recvmsg 2
|
|
calls.
|
|
The option is stored in the following structure in the ancillary data
|
|
returned:
|
|
.Bd -literal
|
|
struct ip6_dest {
|
|
u_int8_t ip6d_nxt; /* next header */
|
|
u_int8_t ip6d_len; /* length in units of 8 octets */
|
|
/* followed by options */
|
|
} __packed;
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fn inet6_option_space
|
|
routine and family of routines may be used to manipulate this data.
|
|
.Pp
|
|
This option requires superuser privileges.
|
|
.It Dv IPV6_RTHDR Fa "int *"
|
|
Get or set whether the routing header from subsequent packets will be
|
|
provided as ancillary data along with the payload in subsequent
|
|
.Xr recvmsg 2
|
|
calls.
|
|
The header is stored in the following structure in the ancillary data
|
|
returned:
|
|
.Bd -literal
|
|
struct ip6_rthdr {
|
|
u_int8_t ip6r_nxt; /* next header */
|
|
u_int8_t ip6r_len; /* length in units of 8 octets */
|
|
u_int8_t ip6r_type; /* routing type */
|
|
u_int8_t ip6r_segleft; /* segments left */
|
|
/* followed by routing-type-specific data */
|
|
} __packed;
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Fn inet6_option_space
|
|
routine and family of routines may be used to manipulate this data.
|
|
.Pp
|
|
This option requires superuser privileges.
|
|
.It Dv IPV6_PKTOPTIONS Fa "struct cmsghdr *"
|
|
Get or set all header options and extension headers at one time on the
|
|
last packet sent or received on the socket.
|
|
All options must fit within the size of an mbuf (see
|
|
.Xr mbuf 9 ) .
|
|
Options are specified as a series of
|
|
.Vt cmsghdr
|
|
structures followed by corresponding values.
|
|
.Va cmsg_level
|
|
is set to
|
|
.Dv IPPROTO_IPV6 ,
|
|
.Va cmsg_type
|
|
to one of the other values in this list, and trailing data to the option
|
|
value.
|
|
When setting options, if the length
|
|
.Va optlen
|
|
to
|
|
.Xr setsockopt 2
|
|
is zero, all header options will be reset to their default values.
|
|
Otherwise, the length should specify the size the series of control
|
|
messages consumes.
|
|
.Pp
|
|
Instead of using
|
|
.Xr sendmsg 2
|
|
to specify option values, the ancillary data used in these calls that
|
|
correspond to the desired header options may be directly specified as
|
|
the control message in the series of control messages provided as the
|
|
argument to
|
|
.Xr setsockopt 2 .
|
|
.It Dv IPV6_CHECKSUM Fa "int *"
|
|
Get or set the byte offset into a packet where the 16-bit checksum is
|
|
located.
|
|
When set, this byte offset is where incoming packets will be expected
|
|
to have checksums of their data stored and where outgoing packets will
|
|
have checksums of their data computed and stored by the kernel.
|
|
A value of \-1 specifies that no checksums will be checked on incoming
|
|
packets and that no checksums will be computed or stored on outgoing
|
|
packets.
|
|
The offset of the checksum for ICMPv6 sockets cannot be relocated or
|
|
turned off.
|
|
.It Dv IPV6_V6ONLY Fa "int *"
|
|
Get or set whether only IPv6 connections can be made to this socket.
|
|
For wildcard sockets, this can restrict connections to IPv6 only.
|
|
.\"With
|
|
.\".Ox
|
|
.\"IPv6 sockets are always IPv6-only, so the socket option is read-only
|
|
.\"(not modifiable).
|
|
.It Dv IPV6_FAITH Fa "int *"
|
|
Get or set the status of whether
|
|
.Xr faith 4
|
|
connections can be made to this socket.
|
|
.It Dv IPV6_USE_MIN_MTU Fa "int *"
|
|
Get or set whether the minimal IPv6 maximum transmission unit (MTU) size
|
|
will be used to avoid fragmentation from occurring for subsequent
|
|
outgoing datagrams.
|
|
.It Dv IPV6_AUTH_LEVEL Fa "int *"
|
|
Get or set the
|
|
.Xr ipsec 4
|
|
authentication level.
|
|
.It Dv IPV6_ESP_TRANS_LEVEL Fa "int *"
|
|
Get or set the ESP transport level.
|
|
.It Dv IPV6_ESP_NETWORK_LEVEL Fa "int *"
|
|
Get or set the ESP encapsulation level.
|
|
.It Dv IPV6_IPCOMP_LEVEL Fa "int *"
|
|
Get or set the
|
|
.Xr ipcomp 4
|
|
level.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Dv IPV6_PKTINFO ,
|
|
.\" .Dv IPV6_NEXTHOP ,
|
|
.Dv IPV6_HOPLIMIT ,
|
|
.Dv IPV6_HOPOPTS ,
|
|
.Dv IPV6_DSTOPTS ,
|
|
and
|
|
.Dv IPV6_RTHDR
|
|
options will return ancillary data along with payload contents in subsequent
|
|
.Xr recvmsg 2
|
|
calls with
|
|
.Va cmsg_level
|
|
set to
|
|
.Dv IPPROTO_IPV6
|
|
and
|
|
.Va cmsg_type
|
|
set to respective option name value (e.g.,
|
|
.Dv IPV6_HOPTLIMIT ) .
|
|
These options may also be used directly as ancillary
|
|
.Va cmsg_type
|
|
values in
|
|
.Xr sendmsg 2
|
|
to set options on the packet being transmitted by the call.
|
|
The
|
|
.Va cmsg_level
|
|
value must be
|
|
.Dv IPPROTO_IPV6 .
|
|
For these options, the ancillary data object value format is the same
|
|
as the value returned as explained for each when received with
|
|
.Xr recvmsg 2 .
|
|
.Pp
|
|
Note that using
|
|
.Xr sendmsg 2
|
|
to specify options on particular packets works only on UDP and raw sockets.
|
|
To manipulate header options for packets on TCP sockets, only the socket
|
|
options may be used.
|
|
.Pp
|
|
In some cases, there are multiple APIs defined for manipulating an IPv6
|
|
header field.
|
|
A good example is the outgoing interface for multicast datagrams, which
|
|
can be set by the
|
|
.Dv IPV6_MULTICAST_IF
|
|
socket option, through the
|
|
.Dv IPV6_PKTINFO
|
|
option, and through the
|
|
.Va sin6_scope_id
|
|
field of the socket address passed to the
|
|
.Xr sendto 2
|
|
system call.
|
|
.Pp
|
|
Resolving these conflicts is implementation dependent.
|
|
This implementation determines the value in the following way:
|
|
options specified by using ancillary data (i.e.,
|
|
.Xr sendmsg 2 )
|
|
are considered first,
|
|
options specified by using
|
|
.Dv IPV6_PKTOPTIONS
|
|
to set
|
|
.Dq sticky
|
|
options are considered second,
|
|
options specified by using the individual, basic, and direct socket
|
|
options (e.g.,
|
|
.Dv IPV6_UNICAST_HOPS )
|
|
are considered third,
|
|
and options specified in the socket address supplied to
|
|
.Xr sendto 2
|
|
are the last choice.
|
|
.Ss Multicasting
|
|
IPv6 multicasting is supported only on
|
|
.Dv AF_INET6
|
|
sockets of type
|
|
.Dv SOCK_DGRAM
|
|
and
|
|
.Dv SOCK_RAW ,
|
|
and only on networks where the interface driver supports
|
|
multicasting.
|
|
Socket options (see above) that manipulate membership of
|
|
multicast groups and other multicast options include
|
|
.Dv IPV6_MULTICAST_IF ,
|
|
.Dv IPV6_MULTICAST_HOPS ,
|
|
.Dv IPV6_MULTICAST_LOOP ,
|
|
.Dv IPV6_LEAVE_GROUP ,
|
|
and
|
|
.Dv IPV6_JOIN_GROUP .
|
|
.Ss Raw Sockets
|
|
Raw IPv6 sockets are connectionless and are normally used with the
|
|
.Xr sendto 2
|
|
and
|
|
.Xr recvfrom 2
|
|
calls, although the
|
|
.Xr connect 2
|
|
call may be used to fix the destination address for future outgoing
|
|
packets so that
|
|
.Xr send 2
|
|
may instead be used and the
|
|
.Xr bind 2
|
|
call may be used to fix the source address for future outgoing
|
|
packets instead of having the kernel choose a source address.
|
|
.Pp
|
|
By using
|
|
.Xr connect 2
|
|
or
|
|
.Xr bind 2 ,
|
|
raw socket input is constrained to only packets with their
|
|
source address matching the socket destination address if
|
|
.Xr connect 2
|
|
was used and to packets with their destination address
|
|
matching the socket source address if
|
|
.Xr bind 2
|
|
was used.
|
|
.Pp
|
|
If the
|
|
.Ar proto
|
|
argument to
|
|
.Xr socket 2
|
|
is zero, the default protocol
|
|
.Pq Dv IPPROTO_RAW
|
|
is used for outgoing packets.
|
|
For incoming packets, protocols recognized by kernel are
|
|
.Sy not
|
|
passed to the application socket (e.g.,
|
|
.Xr tcp 4
|
|
and
|
|
.Xr udp 4 )
|
|
except for some ICMPv6 messages.
|
|
The ICMPv6 messages not passed to raw sockets include echo, timestamp,
|
|
and address mask requests.
|
|
If
|
|
.Ar proto
|
|
is non-zero, only packets with this protocol will be passed to the
|
|
socket.
|
|
.Pp
|
|
IPv6 fragments are also not passed to application sockets until
|
|
they have been reassembled.
|
|
If reception of all packets is desired, link-level access (such as
|
|
.Xr bpf 4 )
|
|
must be used instead.
|
|
.Pp
|
|
Outgoing packets automatically have an IPv6 header prepended to them
|
|
(based on the destination address and the protocol number the socket
|
|
was created with).
|
|
Incoming packets are received by an application without the IPv6 header
|
|
or any extension headers.
|
|
.Pp
|
|
Outgoing packets will be fragmented automatically by the kernel if they
|
|
are too large.
|
|
Incoming packets will be reassembled before being sent to the raw socket,
|
|
so packet fragments or fragment headers will never be seen on a raw socket.
|
|
.Sh EXAMPLES
|
|
The following determines the hop limit on the next packet received:
|
|
.Bd -literal
|
|
struct iovec iov[2];
|
|
u_char buf[BUFSIZ];
|
|
struct cmsghdr *cm;
|
|
struct msghdr m;
|
|
int found, optval;
|
|
u_char data[2048];
|
|
|
|
/* Create socket. */
|
|
|
|
(void)memset(&m, 0, sizeof(m));
|
|
(void)memset(&iov, 0, sizeof(iov));
|
|
|
|
iov[0].iov_base = data; /* buffer for packet payload */
|
|
iov[0].iov_len = sizeof(data); /* expected packet length */
|
|
|
|
m.msg_name = &from; /* sockaddr_in6 of peer */
|
|
m.msg_namelen = sizeof(from);
|
|
m.msg_iov = iov;
|
|
m.msg_iovlen = 1;
|
|
m.msg_control = (caddr_t)buf; /* buffer for control messages */
|
|
m.msg_controllen = sizeof(buf);
|
|
|
|
/*
|
|
* Enable the hop limit value from received packets to be
|
|
* returned along with the payload.
|
|
*/
|
|
optval = 1;
|
|
if (setsockopt(s, IPPROTO_IPV6, IPV6_HOPLIMIT, &optval,
|
|
sizeof(optval)) == -1)
|
|
err(1, "setsockopt");
|
|
|
|
found = 0;
|
|
while (!found) {
|
|
if (recvmsg(s, &m, 0) == -1)
|
|
err(1, "recvmsg");
|
|
for (cm = CMSG_FIRSTHDR(&m); cm != NULL;
|
|
cm = CMSG_NXTHDR(&m, cm)) {
|
|
if (cm->cmsg_level == IPPROTO_IPV6 &&
|
|
cm->cmsg_type == IPV6_HOPLIMIT &&
|
|
cm->cmsg_len == CMSG_LEN(sizeof(int))) {
|
|
found = 1;
|
|
(void)printf("hop limit: %d\en",
|
|
*(int *)CMSG_DATA(cm));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
.Ed
|
|
.Sh DIAGNOSTICS
|
|
A socket operation may fail with one of the following errors returned:
|
|
.Bl -tag -width EADDRNOTAVAILxx
|
|
.It Bq Er 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.
|
|
.It Bq Er ENOTCONN
|
|
when trying to send a datagram, but
|
|
no destination address is specified, and the socket has not been
|
|
connected.
|
|
.It Bq Er ENOBUFS
|
|
when the system runs out of memory for
|
|
an internal data structure.
|
|
.It Bq Er EADDRNOTAVAIL
|
|
when an attempt is made to create a
|
|
socket with a network address for which no network interface
|
|
exists.
|
|
.It Bq Er EACCES
|
|
when an attempt is made to create
|
|
a raw IPv6 socket by a non-privileged process.
|
|
.El
|
|
.Pp
|
|
The following errors specific to IPv6 may occur when setting or getting
|
|
header options:
|
|
.Bl -tag -width EADDRNOTAVAILxx
|
|
.It Bq Er EINVAL
|
|
An unknown socket option name was given.
|
|
.It Bq Er EINVAL
|
|
An ancillary data object was improperly formed.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr getsockopt 2 ,
|
|
.Xr recv 2 ,
|
|
.Xr send 2 ,
|
|
.Xr setsockopt 2 ,
|
|
.Xr socket 2 ,
|
|
.\" .Xr inet6_option_space 3 ,
|
|
.\" .Xr inet6_rthdr_space 3 ,
|
|
.Xr if_nametoindex 3 ,
|
|
.Xr bpf 4 ,
|
|
.Xr icmp6 4 ,
|
|
.Xr inet6 4 ,
|
|
.Xr netintro 4 ,
|
|
.Xr tcp 4 ,
|
|
.Xr udp 4
|
|
.Rs
|
|
.%A W. Stevens
|
|
.%A M. Thomas
|
|
.%T Advanced Sockets API for IPv6
|
|
.%R RFC 2292
|
|
.%D February 1998
|
|
.Re
|
|
.Rs
|
|
.%A S. Deering
|
|
.%A R. Hinden
|
|
.%T Internet Protocol, Version 6 (IPv6) Specification
|
|
.%R RFC 2460
|
|
.%D December 1998
|
|
.Re
|
|
.Rs
|
|
.%A R. Gilligan
|
|
.%A S. Thomson
|
|
.%A J. Bound
|
|
.%A W. Stevens
|
|
.%T Basic Socket Interface Extensions for IPv6
|
|
.%R RFC 2553
|
|
.%D March 1999
|
|
.Re
|
|
.Rs
|
|
.%A W. Stevens
|
|
.%A B. Fenner
|
|
.%A A. Rudoff
|
|
.%T UNIX Network Programming, third edition
|
|
.Re
|
|
.Sh STANDARDS
|
|
Most of the socket options are defined in RFC 2292 or RFC 2553.
|
|
The
|
|
.Dv IPV6_V6ONLY
|
|
socket option is defined in RFC 3542.
|
|
The
|
|
.Dv IPV6_PORTRANGE
|
|
socket option and the conflict resolution rule are not defined in the
|
|
RFCs and should be considered implementation dependent.
|