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[#1584] Suppress v4 NAKs for unknown addresses

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kea-dhcp4 no longer NAKs when the client DHCPREQUESTs
an address that the server does not know.

Added ChangeLog entry

src/bin/dhcp4/dhcp4_messages.*
    DHCP4_UNKNOWN_ADDRESS_REQUESTED - new log message

src/bin/dhcp4/dhcp4_srv.cc
    Dhcpv4Srv::assignLease() - added logic to drop NAKs when
    the address is not managed the server.

src/bin/dhcp4/tests/dora_unittest.cc
src/bin/dhcp4/tests/hooks_unittest.cc
src/bin/dhcp4/tests/out_of_range_unittest.cc
    updated tests

src/lib/dhcpsrv/alloc_engine.*
    AllocEngine::ClientContext4 - added unknown_requested_addr_ flag
    AllocEngine::requestLease4(AllocEngine::ClientContext4& ctx) - sets
    unknown_requested_addr_ flag
This commit is contained in:
Thomas Markwalder
2021-10-11 11:35:53 -04:00
parent 643628f1ff
commit 65d31e57b2
10 changed files with 105 additions and 23 deletions
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31
src/bin/dhcp4/dhcp4_srv.cc
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@@ -2314,6 +2314,7 @@ Dhcpv4Srv::assignLease(Dhcpv4Exchange& ex) {
// it should include this hint. That will help us during the actual lease
// allocation.
bool fake_allocation = (query->getType() == DHCPDISCOVER);
Subnet4Ptr original_subnet = subnet;
// Get client-id. It is not mandatory in DHCPv4.
ClientIdPtr client_id = ex.getContext()->clientid_;
@@ -2329,7 +2330,7 @@ Dhcpv4Srv::assignLease(Dhcpv4Exchange& ex) {
.arg(hint.toText());
Lease4Ptr lease;
Subnet4Ptr original_subnet = subnet;
// Subnet4Ptr original_subnet = subnet;
// We used to issue a separate query (two actually: one for client-id
// and another one for hw-addr for) each subnet in the shared network.
@@ -2573,6 +2574,34 @@ Dhcpv4Srv::assignLease(Dhcpv4Exchange& ex) {
} else {
// Allocation engine did not allocate a lease. The engine logged
// cause of that failure.
if ((ctx->unknown_requested_addr_) /*&& !original_subnet->getAuthoritative()*/) {
Subnet4Ptr s = original_subnet;
// Address might have been rejected via class guard (i.e. not allowed for
// this client). We need to determine if we truly do not know about the
// address or whether this client just isn't allowed to have that address.
// We should only NAK For the latter.
while (s) {
if (s->inPool(Lease::TYPE_V4, hint)) {
break;
}
s = s->getNextSubnet(original_subnet);
}
// If we didn't find a subnet, it's not an address we know about
// so we we drop the NAK.
if (!s) {
LOG_DEBUG(bad_packet4_logger, DBG_DHCP4_DETAIL,
DHCP4_UNKNOWN_ADDRESS_REQUESTED)
.arg(query->getLabel())
.arg(query->getCiaddr().toText())
.arg(opt_requested_address ?
opt_requested_address->readAddress().toText() : "(no address)");
ex.deleteResponse();
return;
}
}
LOG_DEBUG(bad_packet4_logger, DBG_DHCP4_DETAIL, fake_allocation ?
DHCP4_PACKET_NAK_0003 : DHCP4_PACKET_NAK_0004)
.arg(query->getLabel())