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[#2022] Added parking points
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@fxdupont
fxdupont committed Feb 23, 2024
1 parent 00128ad commit 8f254fb
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Showing 5 changed files with 135 additions and 38 deletions.
2 changes: 2 additions & 0 deletions src/bin/dhcp4/dhcp4_messages.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,7 @@ extern const isc::log::MessageID DHCP4_HOOK_PACKET_RCVD_SKIP = "DHCP4_HOOK_PACKE
extern const isc::log::MessageID DHCP4_HOOK_PACKET_SEND_DROP = "DHCP4_HOOK_PACKET_SEND_DROP";
extern const isc::log::MessageID DHCP4_HOOK_PACKET_SEND_SKIP = "DHCP4_HOOK_PACKET_SEND_SKIP";
extern const isc::log::MessageID DHCP4_HOOK_SUBNET4_SELECT_DROP = "DHCP4_HOOK_SUBNET4_SELECT_DROP";
extern const isc::log::MessageID DHCP4_HOOK_SUBNET4_SELECT_PARK = "DHCP4_HOOK_SUBNET4_SELECT_PARK";
extern const isc::log::MessageID DHCP4_HOOK_SUBNET4_SELECT_SKIP = "DHCP4_HOOK_SUBNET4_SELECT_SKIP";
extern const isc::log::MessageID DHCP4_INFORM_DIRECT_REPLY = "DHCP4_INFORM_DIRECT_REPLY";
extern const isc::log::MessageID DHCP4_INIT_FAIL = "DHCP4_INIT_FAIL";
Expand Down Expand Up @@ -279,6 +280,7 @@ const char* values[] = {
"DHCP4_HOOK_PACKET_SEND_DROP", "%1: prepared DHCPv4 response was not sent because a callout set the next ste to DROP",
"DHCP4_HOOK_PACKET_SEND_SKIP", "%1: prepared response is not sent, because a callout set the next stp to SKIP",
"DHCP4_HOOK_SUBNET4_SELECT_DROP", "%1: packet was dropped, because a callout set the next step to 'drop'",
"DHCP4_HOOK_SUBNET4_SELECT_PARK", "%1: packet was parked",
"DHCP4_HOOK_SUBNET4_SELECT_SKIP", "%1: no subnet was selected, because a callout set the next skip flag",
"DHCP4_INFORM_DIRECT_REPLY", "%1: DHCPACK in reply to the DHCPINFORM will be sent directly to %2 over %3",
"DHCP4_INIT_FAIL", "failed to initialize Kea server: %1",
Expand Down
1 change: 1 addition & 0 deletions src/bin/dhcp4/dhcp4_messages.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,7 @@ extern const isc::log::MessageID DHCP4_HOOK_PACKET_RCVD_SKIP;
extern const isc::log::MessageID DHCP4_HOOK_PACKET_SEND_DROP;
extern const isc::log::MessageID DHCP4_HOOK_PACKET_SEND_SKIP;
extern const isc::log::MessageID DHCP4_HOOK_SUBNET4_SELECT_DROP;
extern const isc::log::MessageID DHCP4_HOOK_SUBNET4_SELECT_PARK;
extern const isc::log::MessageID DHCP4_HOOK_SUBNET4_SELECT_SKIP;
extern const isc::log::MessageID DHCP4_INFORM_DIRECT_REPLY;
extern const isc::log::MessageID DHCP4_INIT_FAIL;
Expand Down
7 changes: 6 additions & 1 deletion src/bin/dhcp4/dhcp4_messages.mes
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
# Copyright (C) 2012-2023 Internet Systems Consortium, Inc. ("ISC")
# Copyright (C) 2012-2024 Internet Systems Consortium, Inc. ("ISC")
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
Expand Down Expand Up @@ -523,6 +523,11 @@ point, the setting to that value instructs the server to drop the received
packet. The argument specifies the client and transaction identification
information.

% DHCP4_HOOK_SUBNET4_SELECT_PARK %1: packet was parked
This debug message is printed when a callout installed on the
subnet4_select hook point set the park flag. The argument holds the
client and transaction identification information.

% DHCP4_HOOK_SUBNET4_SELECT_SKIP %1: no subnet was selected, because a callout set the next skip flag
This debug message is printed when a callout installed on the
subnet4_select hook point sets the next step to SKIP value. For this particular hook
Expand Down
118 changes: 95 additions & 23 deletions src/bin/dhcp4/dhcp4_srv.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -715,11 +715,11 @@ Dhcpv4Srv::shutdown() {

isc::dhcp::Subnet4Ptr
Dhcpv4Srv::selectSubnet(const Pkt4Ptr& query, bool& drop,
bool sanity_only) const {
bool sanity_only, bool allow_answer_park) {

// DHCPv4-over-DHCPv6 is a special (and complex) case
if (query->isDhcp4o6()) {
return (selectSubnet4o6(query, drop, sanity_only));
return (selectSubnet4o6(query, drop, sanity_only, allow_answer_park));
}

Subnet4Ptr subnet;
Expand Down Expand Up @@ -751,9 +751,34 @@ Dhcpv4Srv::selectSubnet(const Pkt4Ptr& query, bool& drop,
cfgmgr.getCurrentCfg()->
getCfgSubnets4()->getAll());

// We proactively park the packet.
HooksManager::park("subnet4_select", query,
[this, query, allow_answer_park] () {
processLocalizedQuery4AndSendResponse(query,
allow_answer_park);
});

// Call user (and server-side) callouts
HooksManager::callCallouts(Hooks.hook_index_subnet4_select_,
*callout_handle);
try {
HooksManager::callCallouts(Hooks.hook_index_subnet4_select_,
*callout_handle);
} catch (...) {
// Make sure we don't orphan a parked packet.
HooksManager::drop("subnet4_select", query);
throw;
}

// Callouts parked the packet. Same as drop but callouts will resume
// processing or drop the packet later.
if (callout_handle->getStatus() == CalloutHandle::NEXT_STEP_PARK) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS,
DHCP4_HOOK_SUBNET4_SELECT_PARK)
.arg(query->getLabel());
drop = true;
return (Subnet4Ptr());
} else {
HooksManager::drop("subnet4_select", query);
}

// Callouts decided to skip this step. This means that no subnet
// will be selected. Packet processing will continue, but it will
Expand Down Expand Up @@ -801,7 +826,7 @@ Dhcpv4Srv::selectSubnet(const Pkt4Ptr& query, bool& drop,

isc::dhcp::Subnet4Ptr
Dhcpv4Srv::selectSubnet4o6(const Pkt4Ptr& query, bool& drop,
bool sanity_only) const {
bool sanity_only, bool allow_answer_park) {
Subnet4Ptr subnet;

SubnetSelector selector;
Expand Down Expand Up @@ -861,16 +886,44 @@ Dhcpv4Srv::selectSubnet4o6(const Pkt4Ptr& query, bool& drop,
// handle and its arguments.
ScopedCalloutHandleState callout_handle_state(callout_handle);

// Enable copying options from the packet within hook library.
ScopedEnableOptionsCopy<Pkt4> query4_options_copy(query);

// Set new arguments
callout_handle->setArgument("query4", query);
callout_handle->setArgument("subnet4", subnet);
callout_handle->setArgument("subnet4collection",
cfgmgr.getCurrentCfg()->
getCfgSubnets4()->getAll());

// We proactively park the packet.
HooksManager::park("subnet4_select", query,
[this, query, allow_answer_park] () {
processLocalizedQuery4AndSendResponse(query,
allow_answer_park);
});

// Call user (and server-side) callouts
HooksManager::callCallouts(Hooks.hook_index_subnet4_select_,
*callout_handle);
try {
HooksManager::callCallouts(Hooks.hook_index_subnet4_select_,
*callout_handle);
} catch (...) {
// Make sure we don't orphan a parked packet.
HooksManager::drop("subnet4_select", query);
throw;
}

// Callouts parked the packet. Same as drop but callouts will resume
// processing or drop the packet later.
if (callout_handle->getStatus() == CalloutHandle::NEXT_STEP_PARK) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS,
DHCP4_HOOK_SUBNET4_SELECT_PARK)
.arg(query->getLabel());
drop = true;
return (Subnet4Ptr());
} else {
HooksManager::drop("subnet4_select", query);
}

// Callouts decided to skip this step. This means that no subnet
// will be selected. Packet processing will continue, but it will
Expand Down Expand Up @@ -1147,7 +1200,7 @@ Dhcpv4Srv::processPacketAndSendResponse(Pkt4Ptr query) {
}

Pkt4Ptr
Dhcpv4Srv::processPacket(Pkt4Ptr query, bool allow_packet_park) {
Dhcpv4Srv::processPacket(Pkt4Ptr query, bool allow_answer_park) {
query->addPktEvent("process_started");

// All packets belong to ALL.
Expand Down Expand Up @@ -1326,14 +1379,14 @@ Dhcpv4Srv::processPacket(Pkt4Ptr query, bool allow_packet_park) {
return (Pkt4Ptr());
}

return (processDhcp4Query(query, allow_packet_park));
return (processDhcp4Query(query, allow_answer_park));
}

void
Dhcpv4Srv::processDhcp4QueryAndSendResponse(Pkt4Ptr query,
bool allow_packet_park) {
bool allow_answer_park) {
try {
Pkt4Ptr rsp = processDhcp4Query(query, allow_packet_park);
Pkt4Ptr rsp = processDhcp4Query(query, allow_answer_park);
if (!rsp) {
return;
}
Expand All @@ -1349,7 +1402,7 @@ Dhcpv4Srv::processDhcp4QueryAndSendResponse(Pkt4Ptr query,
}

Pkt4Ptr
Dhcpv4Srv::processDhcp4Query(Pkt4Ptr query, bool allow_packet_park) {
Dhcpv4Srv::processDhcp4Query(Pkt4Ptr query, bool allow_answer_park) {
// Create a client race avoidance RAII handler.
ClientHandler client_handler;

Expand All @@ -1361,7 +1414,7 @@ Dhcpv4Srv::processDhcp4Query(Pkt4Ptr query, bool allow_packet_park) {
(query->getType() == DHCPDECLINE))) {
ContinuationPtr cont =
makeContinuation(std::bind(&Dhcpv4Srv::processDhcp4QueryAndSendResponse,
this, query, allow_packet_park));
this, query, allow_answer_park));
if (!client_handler.tryLock(query, cont)) {
return (Pkt4Ptr());
}
Expand All @@ -1378,7 +1431,7 @@ Dhcpv4Srv::processDhcp4Query(Pkt4Ptr query, bool allow_packet_park) {
(query->getType() == DHCPREQUEST) ||
(query->getType() == DHCPINFORM)) {
bool drop = false;
ctx->subnet_ = selectSubnet(query, drop);
ctx->subnet_ = selectSubnet(query, drop, false, allow_answer_park);
// Stop here if selectSubnet decided to drop the packet
if (drop) {
return (Pkt4Ptr());
Expand All @@ -1402,14 +1455,15 @@ Dhcpv4Srv::processDhcp4Query(Pkt4Ptr query, bool allow_packet_park) {
static_cast<int64_t>(1));
}

return (processLocalizedQuery4(ctx, allow_packet_park));
return (processLocalizedQuery4(ctx, allow_answer_park));
}

void
Dhcpv4Srv::processLocalizedQuery4AndSendResponse(Pkt4Ptr query,
AllocEngine::ClientContext4Ptr& ctx) {
AllocEngine::ClientContext4Ptr& ctx,
bool allow_answer_park) {
try {
Pkt4Ptr rsp = processLocalizedQuery4(ctx, true);
Pkt4Ptr rsp = processLocalizedQuery4(ctx, allow_answer_park);
if (!rsp) {
return;
}
Expand All @@ -1425,9 +1479,27 @@ Dhcpv4Srv::processLocalizedQuery4AndSendResponse(Pkt4Ptr query,
}
}

void
Dhcpv4Srv::processLocalizedQuery4AndSendResponse(Pkt4Ptr query,
bool allow_answer_park) {
// Initialize context.
AllocEngine::ClientContext4Ptr ctx(new AllocEngine::ClientContext4());
initContext0(query, ctx);

// Subnet is cached in the callout context associated to the query.
try {
CalloutHandlePtr callout_handle = getCalloutHandle(query);
callout_handle->getContext("subnet4", ctx->subnet_);
} catch (const Exception&) {
// No subnet, leave it to null...
}

processLocalizedQuery4AndSendResponse(query, ctx, allow_answer_park);
}

Pkt4Ptr
Dhcpv4Srv::processLocalizedQuery4(AllocEngine::ClientContext4Ptr& ctx,
bool allow_packet_park) {
bool allow_answer_park) {
if (!ctx) {
isc_throw(Unexpected, "null context");
}
Expand Down Expand Up @@ -1553,7 +1625,7 @@ Dhcpv4Srv::processLocalizedQuery4(AllocEngine::ClientContext4Ptr& ctx,
callout_handle->setArgument("deleted_leases4", deleted_leases);
}

if (allow_packet_park) {
if (allow_answer_park) {
// Get the parking limit. Parsing should ensure the value is present.
uint32_t parked_packet_limit = 0;
data::ConstElementPtr ppl = CfgMgr::instance().getCurrentCfg()->
Expand Down Expand Up @@ -1636,15 +1708,15 @@ Dhcpv4Srv::processLocalizedQuery4(AllocEngine::ClientContext4Ptr& ctx,
HooksManager::callCallouts(hook_idx, *callout_handle);
} catch (...) {
// Make sure we don't orphan a parked packet.
if (allow_packet_park) {
if (allow_answer_park) {
HooksManager::drop(hook_label, query);
}

throw;
}

if ((callout_handle->getStatus() == CalloutHandle::NEXT_STEP_PARK) &&
allow_packet_park) {
allow_answer_park) {
LOG_DEBUG(hooks_logger, DBG_DHCP4_HOOKS, pkt_park_msg)
.arg(query->getLabel());
// Since the hook library(ies) are going to do the unparking, then
Expand Down Expand Up @@ -4172,7 +4244,7 @@ Dhcpv4Srv::processInform(Pkt4Ptr& inform, AllocEngine::ClientContext4Ptr& contex
}

bool
Dhcpv4Srv::accept(const Pkt4Ptr& query) const {
Dhcpv4Srv::accept(const Pkt4Ptr& query) {
// Check that the message type is accepted by the server. We rely on the
// function called to log a message if needed.
if (!acceptMessageType(query)) {
Expand Down Expand Up @@ -4200,7 +4272,7 @@ Dhcpv4Srv::accept(const Pkt4Ptr& query) const {
}

bool
Dhcpv4Srv::acceptDirectRequest(const Pkt4Ptr& pkt) const {
Dhcpv4Srv::acceptDirectRequest(const Pkt4Ptr& pkt) {
// Accept all relayed messages.
if (pkt->isRelayed()) {
return (true);
Expand Down
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