Commit fb7ab395 authored by Tomek Mrugalski's avatar Tomek Mrugalski 🛰
Browse files

[2984] Hooks Documentation updated.

parent 7d4a5388
......@@ -49,6 +49,32 @@ The following list is ordered by appearance of specific hook points during
packet processing. Hook points that are not specific to packet processing
(e.g. lease expiration) will be added to the end of this list.
@subsection dhcpv6HooksBuffer6Receive buffer6_receive
- @b Arguments:
- name: @b query6, type: isc::dhcp::Pkt6Ptr, direction: <b>in/out</b>
- @b Description: this callout is executed when an incoming DHCPv6
packet is received as a raw buffer. The sole argument - query6 -
contains a pointer to an isc::dhcp::Pkt6 object that contains raw
buffer stored in data_ field. Basic information like protocol,
source/destination addresses and ports are set, but the buffer is
not parsed yet. That means that options_ field that will
eventually contain a list of objects that represent received
options is empty, so all methods that operate on it (e.g.,
getOption()) will not work yet. The primary purpose of this early
call is to offer the ability to modify incoming packets in their
raw form. Unless you need to access raw bytes data, it is usually
better to install your callout on pkt6_receive hook point.
- <b>Skip flag action</b>: If any callout sets the skip flag, the
server will assume that the callout did parse the buffer and added
necessary option objects to the options_ field. Server will not
attempt to do the parsing on its own. If the callout sets skip
flag, but does not parse the buffer, the server will likely drop
the packet due to absence of mandatory options. If you want the
packet to be dropped, see skip falg in pkt6_receive hook point.
@subsection dhcpv6HooksPkt6Receive pkt6_receive
- @b Arguments:
......@@ -89,7 +115,7 @@ packet processing. Hook points that are not specific to packet processing
will continue, but will be severely limited (i.e. only global options
will be assigned).
@subsection dhcpv6HooksLeaseSelect lease6_select
@subsection dhcpv6HooksLease6Select lease6_select
- @b Arguments:
- name: @b subnet6, type: isc::dhcp::Subnet6Ptr, direction: <b>in</b>
......@@ -115,6 +141,55 @@ packet processing. Hook points that are not specific to packet processing
Packet processing will continue and the client may get other addresses
or prefixes if it requested more than one address and/or prefix.
@subsection dhcpv6HooksLease6Renew lease6_renew
- @b Arguments:
- name: @b query6, type: isc::dhcp::PktPtr, direction: <b>in</b>
- name: @b lease6, type: isc::dhcp::Lease6Ptr, direction: <b>in/out</b>
- name: @b ia_na, type: boost::shared_ptr<Option6IA>, direction: <b>in/out</b>
- @b Description: this callout is executed after the server engine is
about to renew an existing lease. Client's request is provided as
the query6 argument. Existing lease with already modified values is
provided in lease6 parameter. The IA_NA option that will be sent
back to the client is provided as the ia_na argument. Callouts
installed on the lease6_renew may modify content of the
lease6. Care should be taken as that modified value will be then
applied to the database without any sanity checks. Although
envisaged usage assumes modification of T1, T2, preferred and valid
lifetimes only, other parameters may be modified as well. The only
exception is addr_ field, which must not be modified as it is used
by the database to select the existing lease to be updated. Care should
be taken to also modify ia_na option to match any changes in the lease6.
If a client sends more than one IA_NA option, callouts will be called
separately for each IA_NA instance. The callout will be called only
when the update is valid, i.e. unknown, invalid address, invalid iaid
renewal attempts will not trigger this hook point.
- <b>Skip flag action</b>: If any callout installed on 'lease6_renew'
sets the skip flag, the server will not renew the lease. It will, however,
send back the IA_NA option that looks like if the server did renew
the lease. It is recommended to modify ia_na option to reflect the
fact that the lease was not updated. Otherwise the client will think
that the lease was renewed, but it fact it was not.
@subsection dhcpv6HooksLease6Release lease6_release
- @b Arguments:
- name: @b query6, type: isc::dhcp::PktPtr, direction: <b>in</b>
- name: @b lease6, type: isc::dhcp::Lease6Ptr, direction: <b>in/out</b>
- @b Description: this callout is executed after the server engine is
about to release an existing lease. Client's request is provided as
the query6 argument. Existing lease to be released is
provided in lease6 parameter. It doesn't make much sense to modify
existing lease6 at this point as it will be destroyed immediately
after the callouts conclude their execution.
- <b>Skip flag action</b>: If any callout installed on 'lease6_release'
sets the skip flag, the server will not delete the lease. However,
it will send out the response back to the client as if it did.
@subsection dhcpv6HooksPkt6Send pkt6_send
- @b Arguments:
......@@ -130,6 +205,28 @@ packet processing. Hook points that are not specific to packet processing
pkt6_send callouts are complete, so any changes to that field will
be overwritten.)
- <b>Skip flag action</b>: if any callout sets the skip flag, the server
will assume that the callout did pack transaction-id, mesage type and
option objects into bufferOut_ field and will skip packing part.
Note that if the callout set skip flag, but did not prepare the
output buffer, the server will send zero sized message that will be
ignored by the client. If you want to drop the packet, please see
skip flag in buffer6_send hook point.
@subsection dhcpv6HooksBuffer6Send buffer6_send
- @b Arguments:
- name: @b response6, type: isc::dhcp::Pkt6Ptr, direction: <b>in/out</b>
- @b Description: this callout is executed when server's response is
assembled into binary form and is about to be send back to the
client. The sole argument - response6 - contains a pointer to an
isc::dhcp::Pkt6 object that contains the packet, with set source
and destination addresses, interface over which it will be send,
list of all options and relay information. All options are already
encoded in bufferOut_ field. It doesn't make sense to modify any
options at that time as their binary form was already prepared.
- <b>Skip flag action</b>: if any callout sets the skip flag, the server
will drop this response packet. However, the original request packet
from a client was processed, so server's state was most likely changed
......
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