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Commit 568a6bee authored by Marcin Siodelski's avatar Marcin Siodelski
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[3768] Extended commentary in the allocation engine to cover recent changes.

parent a4bc5674
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src/bin/dhcp4/tests/dora_unittest.cc
View file @ 568a6bee
......@@ -173,11 +173,64 @@ public:
IfaceMgr::instance().openSockets4();
}
/// @brief Test that server doesn't allocate the lease for the client
/// which has the same address or client identifier as another client.
///
/// This test checks the server's behavior in the following scenario:
/// - Client A identifies itself to the server using the hardware address
/// and client identifier or only one of those.
/// - Client A performs the 4-way exchange and obtains a lease from the server.
/// - Client B uses the same HW address or client identifier as the client A.
/// - Client B uses HW address and client identifier if the client A is using
/// only the one of them. Client B uses one of the HW address or client
/// identifier if the client A is using both.
/// - Client B sends the DHCPDISCOVER to the server.
/// The server determines that there is a lease for the client A using the
/// same HW address as the client B. Server discards the client's message and
/// doesn't offer the lease for the client B to prevent allocation of the
/// lease without a unique identifier.
/// - The client sends the DHCPREQUEST and the server sends the DHCPNAK for the
/// same reason.
///
/// The specific test cases using this test must make sure that one of the
/// provided parameters is an empty string. This simulates the situation where
/// one of the clients has only one of the identifiers and the other one has
/// two.
///
/// @param hwaddr_a HW address of client A.
/// @param clientid_a Client id of client A.
/// @param hwaddr_b HW address of client B.
/// @param clientid_b Client id of client B.
void oneAllocationOverlapTest(const std::string& hwaddr_a,
const std::string& clientid_a,
const std::string& hwaddr_b,
const std::string& clientid_b);
/// @brief Test that server can allocate the lease for the client having
/// the same HW Address or client id as another client.
///
/// This test checks the server behavior in the following situation:
/// - Client A identifies itself to the server using client identifier
/// and the hardware address and requests allocation of the new lease.
/// - Server allocates the lease to the client.
/// - Client B has a different hardware address or client identifier than
/// the client A, but the other identifier is equal to the corresponding
/// identifier of the client A.
/// - Client B sends DHCPDISCOVER.
/// - Server should determine that the client B is not client A, because
/// it is using a different hadrware address or client identifier, even
/// As a consequence, the server should offer a different address to the
/// client B.
/// - The client B performs the 4-way exchange again, and the server
/// allocates a new address to the client, which should be different
/// than the address used by the client A.
/// - Client B is in the renewing state and it successfully renews its
/// address.
///
/// @param hwaddr_a HW address of client A.
/// @param clientid_a Client id of client A.
/// @param hwaddr_b HW address of client B.
/// @param clientid_b Client id of client B.
void twoAllocationsOverlapTest(const std::string& hwaddr_a,
const std::string& clientid_a,
const std::string& hwaddr_b,
......@@ -467,10 +520,12 @@ DORATest::twoAllocationsOverlapTest(const std::string& hwaddr_a,
Pkt4Ptr resp_a = client_a.getContext().response_;
// Make sure that the server has responded with DHCPACK.
ASSERT_EQ(DHCPACK, static_cast<int>(resp_a->getType()));
// Make sure that the lease has been recorded by the server.
Lease4Ptr lease_a = LeaseMgrFactory::instance().getLease4(client_a.config_.lease_.addr_);
ASSERT_TRUE(lease_a);
// Use the same client identifier by client B.
// Create client B.
Dhcp4Client client_b(client_a.getServer(), Dhcp4Client::SELECTING);
client_b.setHWAddress(hwaddr_b);
client_b.includeClientId(clientid_b);
......@@ -483,6 +538,7 @@ DORATest::twoAllocationsOverlapTest(const std::string& hwaddr_a,
// was obtained by the client A.
ASSERT_NE(resp_b->getYiaddr(), client_a.config_.lease_.addr_);
// Make sure that the client A lease hasn't been modified.
lease_a = LeaseMgrFactory::instance().getLease4(client_a.config_.lease_.addr_);
ASSERT_TRUE(lease_a);
......@@ -494,13 +550,15 @@ DORATest::twoAllocationsOverlapTest(const std::string& hwaddr_a,
ASSERT_TRUE(client_b.getContext().response_);
resp_b = client_b.getContext().response_;
// Make sure that the server has responded with DHCPACK.
ASSERT_EQ(DHCPACK, static_cast<int>(resp_b->getType()));
// Again, make sure the assigned addresses are different.
ASSERT_NE(client_b.config_.lease_.addr_, client_a.config_.lease_.addr_);
// Make sure that the client A still has a lease.
lease_a = LeaseMgrFactory::instance().getLease4(client_a.config_.lease_.addr_);
ASSERT_TRUE(lease_a);
// Make sure that the client B has a lease.
Lease4Ptr lease_b = LeaseMgrFactory::instance().getLease4(client_b.config_.lease_.addr_);
ASSERT_TRUE(lease_b);
......@@ -536,11 +594,18 @@ DORATest::oneAllocationOverlapTest(const std::string& hwaddr_a,
Dhcp4Client client_b(client_a.getServer(), Dhcp4Client::SELECTING);
client_b.setHWAddress(hwaddr_b);
client_b.includeClientId(clientid_b);
// Send DHCPDISCOVER and expect the response.
// Client A and Client B have one common identifier (HW address
// or client identifier) and one of them is missing the other
// identifier. The allocation engine can't offer an address for
// the client which has the same identifier as the other client and
// which doesn't have any other (unique) identifier. It should
// discard the DHCPDISCOVER.
ASSERT_NO_THROW(client_b.doDiscover());
Pkt4Ptr resp_b = client_b.getContext().response_;
ASSERT_FALSE(resp_b);
// Now repeat the same test but send the DHCPREQUEST. This time the
// server should send the DHCPNAK.
client_b.config_.lease_.addr_ = IOAddress::IPV4_ZERO_ADDRESS();
client_b.setState(Dhcp4Client::INIT_REBOOT);
ASSERT_NO_THROW(client_b.doRequest());
......@@ -574,16 +639,34 @@ TEST_F(DORATest, twoAllocationsOverlap1) {
"02:02:03:03:04:04", "12:34");
}
// This test is similar to twoAllocationsOverlap1, but the
// clients differ by client identifier.
TEST_F(DORATest, twoAllocationsOverlap2) {
twoAllocationsOverlapTest("01:02:03:04:05:06", "12:34",
"01:02:03:04:05:06", "22:34");
}
// This test checks the server behavior in the following situation:
// - Client A identifies itself to the server using the hardware address
// and client identifier.
// - Client A performs the 4-way exchange and obtains a lease from the server.
// - Client B uses the same HW address as the client A, but it doesn't use
// the client identifier.
// - Client B sends the DHCPDISCOVER to the server.
// The server determines that there is a lease for the client A using the
// same HW address as the client B. Server discards the client's message and
// doesn't offer the lease for the client B to prevent allocation of the
// lease without a unique identifier.
// - The client sends the DHCPREQUEST and the server sends the DHCPNAK for the
// same reason.
TEST_F(DORATest, oneAllocationOverlap1) {
oneAllocationOverlapTest("01:02:03:04:05:06", "12:34",
"01:02:03:04:05:06", "");
}
// This test is similar to oneAllocationOverlap2 but this time the client A
// uses no client identifier, and the client B uses the HW address and the
// client identifier. The server behaves as previously.
TEST_F(DORATest, oneAllocationOverlap2) {
oneAllocationOverlapTest("01:02:03:04:05:06", "",
"01:02:03:04:05:06", "12:34");
......
src/lib/dhcpsrv/alloc_engine.cc
View file @ 568a6bee
......@@ -1351,21 +1351,39 @@ AllocEngine::discoverLease4(AllocEngine::ClientContext4& ctx) {
// Obtain the sole instance of the LeaseMgr.
LeaseMgr& lease_mgr = LeaseMgrFactory::instance();
// Check if the client has any lease already. This information is needed
// to either return this lease to the client or to return it as an old
// (existing) lease if a different one is offered.
// The server should hand out existing lease to the client, so we have to check
// if there is one. First, try to use the client's HW address.
Lease4Ptr client_lease = lease_mgr.getLease4(*ctx.hwaddr_, ctx.subnet_->getID());
// If there is no lease for this HW address or the lease doesn't seem to be ours,
// we will have to use the client identifier. Note that in some situations two
// clients may use the same HW address so even if we find the lease for the HW
// address it doesn't mean it is ours, because client identifier may not match.
if (ctx.clientid_ && ((!client_lease) || (client_lease && !ctx.myLease(*client_lease)))) {
// Check if the lease is in conflict with the lease that we want to allocate.
// If the lease is in conflict because of using overlapping HW address or
// client identifier, we can't allocate the lease for this client.
if (client_lease && ctx.isInConflict(*client_lease)) {
return (Lease4Ptr());
}
// There is no lease or the lease we found is not conflicting with the lease
// which we have found for the HW address, so there is still a chance that
// we will allocate the lease. Check if there is a lease using the client
// identifier.
client_lease = lease_mgr.getLease4(*ctx.clientid_, ctx.subnet_->getID());
}
// Check if the lease we have found belongs to us.
if (client_lease && !ctx.myLease(*client_lease)) {
// If the lease doesn't belong to us, check if we can add new lease for
// the client which message we're processing, or its identifiers are
// in conflict with this lease.
if (ctx.isInConflict(*client_lease)) {
return (Lease4Ptr());
}
// If there is no conflict we can proceed and try to find the appropriate
// lease but we don't use the one we found, because it is assigned to
// someone else. Reset the pointer to indicate that we're not
// renewing this lease.
client_lease.reset();
}
......@@ -1452,15 +1470,39 @@ AllocEngine::requestLease4(AllocEngine::ClientContext4& ctx) {
// Obtain the sole instance of the LeaseMgr.
LeaseMgr& lease_mgr = LeaseMgrFactory::instance();
// Check if the client has any lease already. This information is needed
// to either return this lease to the client or to return it as an old
// (existing) lease if a different one is offered.
// The server should hand out existing lease to the client, so we have to check
// if there is one. First, try to use the client's HW address.
Lease4Ptr client_lease = lease_mgr.getLease4(*ctx.hwaddr_, ctx.subnet_->getID());
// If there is no lease for this HW address or the lease doesn't seem to be ours,
// we will have to use the client identifier. Note that in some situations two
// clients may use the same HW address so even if we find the lease for the HW
// address it doesn't mean it is ours, because client identifier may not match.
if (ctx.clientid_ && ((!client_lease) || (client_lease && !ctx.myLease(*client_lease)))) {
// Check if the lease is in conflict with the lease that we want to allocate.
// If the lease is in conflict because of using overlapping HW address or
// client identifier, we can't allocate the lease for this client.
if (client_lease && ctx.isInConflict(*client_lease)) {
return (Lease4Ptr());
}
// There is no lease or the lease we found is not conflicting with the lease
// which we have found for the HW address, so there is still a chance that
// we will allocate the lease. Check if there is a lease using the client
// identifier.
client_lease = lease_mgr.getLease4(*ctx.clientid_, ctx.subnet_->getID());
}
// Check if the lease we have found belongs to us.
if (client_lease && !ctx.myLease(*client_lease)) {
// If the lease doesn't belong to us, check if we can add new lease for
// the client which message we're processing, or its identifiers are
// in conflict with this lease.
if (ctx.isInConflict(*client_lease)) {
return (Lease4Ptr());
}
// If there is no conflict we can proceed and try to find the appropriate
// lease but we don't use the one we found, because it is assigned to
// someone else. Reset the pointer to indicate that we're not
// renewing this lease.
client_lease.reset();
}
......
src/lib/dhcpsrv/alloc_engine.h
View file @ 568a6bee
......@@ -765,6 +765,32 @@ public:
/// the context has been created, false otherwise.
bool myLease(const Lease4& lease) const;
/// @brief Check if the lease conflicts with the context.
///
/// This method is used in cases when there is a lease in the lease database
/// for the client and the server receives the message from another client
/// which may be potentially using the same client identifier or HW address.
///
/// Currently the allocation engine allows for allocating a lease for the
/// client which is using the same HW address or client identifier as the
/// client which already has a lease in the database. However, the value of
/// one of the identifiers must be unique. In other words, two clients may
/// have the same client identifier but different HW addresses and the
/// leases can be allocated for both (there is no conflict).
///
/// The other possible case is that one of the clients uses both HW address
/// and client identifier, and another client is using only one of those
/// and its value is the same as for the former client. The allocation
/// engine treats it as a conflict because there is no unique value in the
/// lease database by which the server could distinguish the clients.
/// Hence, it doesn't allocate the lease from the context in conflict.
///
/// This method detects the conflict described above.
///
/// @param lease Existing lease to be checked.
///
/// @return true if the lease is in conflict with the context, false
/// otherwise.
bool isInConflict(const Lease4& lease) const;
};
......
src/lib/dhcpsrv/tests/alloc_engine4_unittest.cc
View file @ 568a6bee
......@@ -761,7 +761,9 @@ TEST_F(AllocEngine4Test, reservedAddressExistingLease) {
// Create a lease for the client with a different address than the reserved
// one.
Lease4Ptr lease(new Lease4(IOAddress("192.0.2.101"), hwaddr_, 0, 0,
Lease4Ptr lease(new Lease4(IOAddress("192.0.2.101"), hwaddr_,
&clientid_->getClientId()[0],
clientid_->getClientId().size(),
100, 30, 60, time(NULL), subnet_->getID(),
false, false, ""));
LeaseMgrFactory::instance().addLease(lease);
......@@ -1036,7 +1038,9 @@ TEST_F(AllocEngine4Test, reservedAddressExistingLeaseNoHint) {
CfgMgr::instance().commit();
// Create a lease for a different address than reserved.
Lease4Ptr lease(new Lease4(IOAddress("192.0.2.101"), hwaddr_, 0, 0,
Lease4Ptr lease(new Lease4(IOAddress("192.0.2.101"), hwaddr_,
&clientid_->getClientId()[0],
clientid_->getClientId().size(),
100, 30, 60, time(NULL), subnet_->getID(),
false, false, ""));
LeaseMgrFactory::instance().addLease(lease);
......@@ -1148,7 +1152,9 @@ TEST_F(AllocEngine4Test, reservedAddressConflictResolution) {
CfgMgr::instance().commit();
// Create a lease for Client A.
Lease4Ptr lease(new Lease4(IOAddress("192.0.2.101"), hwaddr_, 0, 0,
Lease4Ptr lease(new Lease4(IOAddress("192.0.2.101"), hwaddr_,
&clientid_->getClientId()[0],
clientid_->getClientId().size(),
100, 30, 60, time(NULL), subnet_->getID(),
false, false, ""));
LeaseMgrFactory::instance().addLease(lease);
......
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