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path: root/pkg/tcpip/stack/nud.go
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2021-01-31Hide neighbor table kind from NetworkEndpointGhanan Gowripalan
The network endpoint should not need to have logic to handle different kinds of neighbor tables. Network endpoints can let the NIC know about differnt neighbor discovery messages and let the NIC decide which table to update. This allows us to remove the LinkAddressCache interface. PiperOrigin-RevId: 354812584
2021-01-27Confirm neighbor reachability with TCP ACKsGhanan Gowripalan
As per RFC 4861 section 7.3.1, A neighbor is considered reachable if the node has recently received a confirmation that packets sent recently to the neighbor were received by its IP layer. Positive confirmation can be gathered in two ways: hints from upper-layer protocols that indicate a connection is making "forward progress", or receipt of a Neighbor Advertisement message that is a response to a Neighbor Solicitation message. This change adds support for TCP to let the IP/link layers know that a neighbor is reachable. Test: integration_test.TestTCPConfirmNeighborReachability PiperOrigin-RevId: 354222833
2020-12-22Invoke address resolution upon subsequent traffic to Failed neighborPeter Johnston
Removes the period of time in which subseqeuent traffic to a Failed neighbor immediately fails with ErrNoLinkAddress. A Failed neighbor is one in which address resolution fails; or in other words, the neighbor's IP address cannot be translated to a MAC address. This means removing the Failed state for linkAddrCache and allowing transitiong out of Failed into Incomplete for neighborCache. Previously, both caches would transition entries to Failed after address resolution fails. In this state, any subsequent traffic requested within an unreachable time would immediately fail with ErrNoLinkAddress. This does not follow RFC 4861 section 7.3.3: If address resolution fails, the entry SHOULD be deleted, so that subsequent traffic to that neighbor invokes the next-hop determination procedure again. Invoking next-hop determination at this point ensures that alternate default routers are tried. The API for getting a link address for a given address, whether through the link address cache or the neighbor table, is updated to optionally take a callback which will be called when address resolution completes. This allows `Route` to handle completing link resolution internally, so callers of (*Route).Resolve (e.g. endpoints) don’t have to keep track of when it completes and update the Route accordingly. This change also removes the wakers from LinkAddressCache, NeighborCache, and Route in favor of the callbacks, and callers that previously used a waker can now just pass a callback to (*Route).Resolve that will notify the waker on resolution completion. Fixes #4796 Startblock: has LGTM from sbalana and then add reviewer ghanan PiperOrigin-RevId: 348597478
2020-12-17Remove duplicate `return`Tamir Duberstein
PiperOrigin-RevId: 347974624
2020-10-27Pass NeighborEntry in NUD callbacksTamir Duberstein
...instead of passing its fields piecemeal. PiperOrigin-RevId: 339345899
2020-10-23Do not hold NIC local address in neighbor entriesGhanan Gowripalan
Previously, the NIC local address used when completing link resolution was held in the neighbor entry. A neighbor is not identified by any NIC local address so remove it. PiperOrigin-RevId: 338699695
2020-08-07Fix panic during Address Resolution of neighbor entry created by NSSam Balana
When a Neighbor Solicitation is received, a neighbor entry is created with the remote host's link layer address, but without a link layer address resolver. If the host decides to send a packet addressed to the IP address of that neighbor entry, Address Resolution starts with a nil pointer to the link layer address resolver. This causes the netstack to panic and crash. This change ensures that when a packet is sent in that situation, the link layer address resolver will be set before Address Resolution begins. Tests: pkg/tcpip/stack:stack_test + TestEntryUnknownToStaleToProbeToReachable - TestNeighborCacheEntryNoLinkAddress Updates #1889 Updates #1894 Updates #1895 Updates #1947 Updates #1948 Updates #1949 Updates #1950 PiperOrigin-RevId: 325516471
2020-07-30Implement neighbor unreachability detection for ARP and NDP.Sam Balana
This change implements the Neighbor Unreachability Detection (NUD) state machine, as per RFC 4861 [1]. The state machine operates on a single neighbor in the local network. This requires the state machine to be implemented on each entry of the neighbor table. This change also adds, but does not expose, several APIs. The first API is for performing basic operations on the neighbor table: - Create a static entry - List all entries - Delete all entries - Remove an entry by address The second API is used for changing the NUD protocol constants on a per-NIC basis to allow Neighbor Discovery to operate over links with widely varying performance characteristics. See [RFC 4861 Section 10][2] for the list of constants. Finally, the last API is for allowing users to subscribe to NUD state changes. See [RFC 4861 Appendix C][3] for the list of edges. [1]: https://tools.ietf.org/html/rfc4861 [2]: https://tools.ietf.org/html/rfc4861#section-10 [3]: https://tools.ietf.org/html/rfc4861#appendix-C Tests: pkg/tcpip/stack:stack_test - TestNeighborCacheAddStaticEntryThenOverflow - TestNeighborCacheClear - TestNeighborCacheClearThenOverflow - TestNeighborCacheConcurrent - TestNeighborCacheDuplicateStaticEntryWithDifferentLinkAddress - TestNeighborCacheDuplicateStaticEntryWithSameLinkAddress - TestNeighborCacheEntry - TestNeighborCacheEntryNoLinkAddress - TestNeighborCacheGetConfig - TestNeighborCacheKeepFrequentlyUsed - TestNeighborCacheNotifiesWaker - TestNeighborCacheOverflow - TestNeighborCacheOverwriteWithStaticEntryThenOverflow - TestNeighborCacheRemoveEntry - TestNeighborCacheRemoveEntryThenOverflow - TestNeighborCacheRemoveStaticEntry - TestNeighborCacheRemoveStaticEntryThenOverflow - TestNeighborCacheRemoveWaker - TestNeighborCacheReplace - TestNeighborCacheResolutionFailed - TestNeighborCacheResolutionTimeout - TestNeighborCacheSetConfig - TestNeighborCacheStaticResolution - TestEntryAddsAndClearsWakers - TestEntryDelayToProbe - TestEntryDelayToReachableWhenSolicitedOverrideConfirmation - TestEntryDelayToReachableWhenUpperLevelConfirmation - TestEntryDelayToStaleWhenConfirmationWithDifferentAddress - TestEntryDelayToStaleWhenProbeWithDifferentAddress - TestEntryFailedGetsDeleted - TestEntryIncompleteToFailed - TestEntryIncompleteToIncompleteDoesNotChangeUpdatedAt - TestEntryIncompleteToReachable - TestEntryIncompleteToReachableWithRouterFlag - TestEntryIncompleteToStale - TestEntryInitiallyUnknown - TestEntryProbeToFailed - TestEntryProbeToReachableWhenSolicitedConfirmationWithSameAddress - TestEntryProbeToReachableWhenSolicitedOverrideConfirmation - TestEntryProbeToStaleWhenConfirmationWithDifferentAddress - TestEntryProbeToStaleWhenProbeWithDifferentAddress - TestEntryReachableToStaleWhenConfirmationWithDifferentAddress - TestEntryReachableToStaleWhenConfirmationWithDifferentAddressAndOverride - TestEntryReachableToStaleWhenProbeWithDifferentAddress - TestEntryReachableToStaleWhenTimeout - TestEntryStaleToDelay - TestEntryStaleToReachableWhenSolicitedOverrideConfirmation - TestEntryStaleToStaleWhenOverrideConfirmation - TestEntryStaleToStaleWhenProbeUpdateAddress - TestEntryStaysDelayWhenOverrideConfirmationWithSameAddress - TestEntryStaysProbeWhenOverrideConfirmationWithSameAddress - TestEntryStaysReachableWhenConfirmationWithRouterFlag - TestEntryStaysReachableWhenProbeWithSameAddress - TestEntryStaysStaleWhenProbeWithSameAddress - TestEntryUnknownToIncomplete - TestEntryUnknownToStale - TestEntryUnknownToUnknownWhenConfirmationWithUnknownAddress pkg/tcpip/stack:stack_x_test - TestDefaultNUDConfigurations - TestNUDConfigurationFailsForNotSupported - TestNUDConfigurationsBaseReachableTime - TestNUDConfigurationsDelayFirstProbeTime - TestNUDConfigurationsMaxMulticastProbes - TestNUDConfigurationsMaxRandomFactor - TestNUDConfigurationsMaxUnicastProbes - TestNUDConfigurationsMinRandomFactor - TestNUDConfigurationsRetransmitTimer - TestNUDConfigurationsUnreachableTime - TestNUDStateReachableTime - TestNUDStateRecomputeReachableTime - TestSetNUDConfigurationFailsForBadNICID - TestSetNUDConfigurationFailsForNotSupported [1]: https://tools.ietf.org/html/rfc4861 [2]: https://tools.ietf.org/html/rfc4861#section-10 [3]: https://tools.ietf.org/html/rfc4861#appendix-C Updates #1889 Updates #1894 Updates #1895 Updates #1947 Updates #1948 Updates #1949 Updates #1950 PiperOrigin-RevId: 324070795