diff options
| -rw-r--r-- | pkg/tcpip/stack/neighbor_cache.go | 7 | ||||
| -rw-r--r-- | pkg/tcpip/stack/nic.go | 6 | ||||
| -rw-r--r-- | pkg/tcpip/stack/nud.go | 4 | ||||
| -rw-r--r-- | pkg/tcpip/stack/route.go | 23 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/connect.go | 8 | ||||
| -rw-r--r-- | pkg/tcpip/transport/tcp/snd.go | 11 |
6 files changed, 45 insertions, 14 deletions
diff --git a/pkg/tcpip/stack/neighbor_cache.go b/pkg/tcpip/stack/neighbor_cache.go index 204196d00..eea32dcf5 100644 --- a/pkg/tcpip/stack/neighbor_cache.go +++ b/pkg/tcpip/stack/neighbor_cache.go @@ -297,10 +297,9 @@ func (n *neighborCache) HandleConfirmation(addr tcpip.Address, linkAddr tcpip.Li // no matching entry for the remote address. } -// HandleUpperLevelConfirmation implements -// NUDHandler.HandleUpperLevelConfirmation by following the logic defined in -// RFC 4861 section 7.3.1. -func (n *neighborCache) HandleUpperLevelConfirmation(addr tcpip.Address) { +// handleUpperLevelConfirmation processes a confirmation of reachablity from +// some protocol that operates at a layer above the IP/link layer. +func (n *neighborCache) handleUpperLevelConfirmation(addr tcpip.Address) { n.mu.RLock() entry, ok := n.cache[addr] n.mu.RUnlock() diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go index 1bbfe6213..f59416fd3 100644 --- a/pkg/tcpip/stack/nic.go +++ b/pkg/tcpip/stack/nic.go @@ -561,6 +561,12 @@ func (n *NIC) removeAddress(addr tcpip.Address) *tcpip.Error { return tcpip.ErrBadLocalAddress } +func (n *NIC) confirmReachable(addr tcpip.Address) { + if n := n.neigh; n != nil { + n.handleUpperLevelConfirmation(addr) + } +} + func (n *NIC) getNeighborLinkAddress(addr, localAddr tcpip.Address, linkRes LinkAddressResolver, onResolve func(LinkResolutionResult)) (tcpip.LinkAddress, <-chan struct{}, *tcpip.Error) { if n.neigh != nil { entry, ch, err := n.neigh.entry(addr, localAddr, linkRes, onResolve) diff --git a/pkg/tcpip/stack/nud.go b/pkg/tcpip/stack/nud.go index 12d67409a..77926e289 100644 --- a/pkg/tcpip/stack/nud.go +++ b/pkg/tcpip/stack/nud.go @@ -174,10 +174,6 @@ type NUDHandler interface { // HandleConfirmation processes an incoming neighbor confirmation (e.g. ARP // reply or Neighbor Advertisement for ARP or NDP, respectively). HandleConfirmation(addr tcpip.Address, linkAddr tcpip.LinkAddress, flags ReachabilityConfirmationFlags) - - // HandleUpperLevelConfirmation processes an incoming upper-level protocol - // (e.g. TCP acknowledgements) reachability confirmation. - HandleUpperLevelConfirmation(addr tcpip.Address) } // NUDConfigurations is the NUD configurations for the netstack. This is used diff --git a/pkg/tcpip/stack/route.go b/pkg/tcpip/stack/route.go index d9a8554e2..9c8c155fa 100644 --- a/pkg/tcpip/stack/route.go +++ b/pkg/tcpip/stack/route.go @@ -354,11 +354,6 @@ func (r *Route) resolvedFields(afterResolve func(ResolvedFieldsResult)) (RouteIn return fields, nil, nil } - nextAddr := r.NextHop - if nextAddr == "" { - nextAddr = r.RemoteAddress - } - // If specified, the local address used for link address resolution must be an // address on the outgoing interface. var linkAddressResolutionRequestLocalAddr tcpip.Address @@ -367,7 +362,7 @@ func (r *Route) resolvedFields(afterResolve func(ResolvedFieldsResult)) (RouteIn } afterResolveFields := fields - linkAddr, ch, err := r.outgoingNIC.getNeighborLinkAddress(nextAddr, linkAddressResolutionRequestLocalAddr, r.linkRes, func(r LinkResolutionResult) { + linkAddr, ch, err := r.outgoingNIC.getNeighborLinkAddress(r.nextHop(), linkAddressResolutionRequestLocalAddr, r.linkRes, func(r LinkResolutionResult) { if afterResolve != nil { if r.Success { afterResolveFields.RemoteLinkAddress = r.LinkAddress @@ -382,6 +377,13 @@ func (r *Route) resolvedFields(afterResolve func(ResolvedFieldsResult)) (RouteIn return fields, ch, err } +func (r *Route) nextHop() tcpip.Address { + if len(r.NextHop) == 0 { + return r.RemoteAddress + } + return r.NextHop +} + // local returns true if the route is a local route. func (r *Route) local() bool { return r.Loop == PacketLoop || r.outgoingNIC.IsLoopback() @@ -519,3 +521,12 @@ func (r *Route) IsOutboundBroadcast() bool { // Only IPv4 has a notion of broadcast. return r.isV4Broadcast(r.RemoteAddress) } + +// ConfirmReachable informs the network/link layer that the neighbour used for +// the route is reachable. +// +// "Reachable" is defined as having full-duplex communication between the +// local and remote ends of the route. +func (r *Route) ConfirmReachable() { + r.outgoingNIC.confirmReachable(r.nextHop()) +} diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 62954d7e4..6df4e6525 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -1335,6 +1335,14 @@ func (e *endpoint) protocolMainLoop(handshake bool, wakerInitDone chan<- struct{ } } + // Reaching this point means that we successfully completed the 3-way + // handshake with our peer. + // + // Completing the 3-way handshake is an indication that the route is valid + // and the remote is reachable as the only way we can complete a handshake + // is if our SYN reached the remote and their ACK reached us. + e.route.ConfirmReachable() + drained := e.drainDone != nil if drained { close(e.drainDone) diff --git a/pkg/tcpip/transport/tcp/snd.go b/pkg/tcpip/transport/tcp/snd.go index 28ef9f899..027c2a4a8 100644 --- a/pkg/tcpip/transport/tcp/snd.go +++ b/pkg/tcpip/transport/tcp/snd.go @@ -1390,6 +1390,17 @@ func (s *sender) handleRcvdSegment(rcvdSeg *segment) { acked := s.sndUna.Size(ack) s.sndUna = ack + // The remote ACK-ing at least 1 byte is an indication that we have a + // full-duplex connection to the remote as the only way we will receive an + // ACK is if the remote received data that we previously sent. + // + // As of writing, linux seems to only confirm a route as reachable when + // forward progress is made which is indicated by an ACK that removes data + // from the retransmit queue. + if acked > 0 { + s.ep.route.ConfirmReachable() + } + ackLeft := acked originalOutstanding := s.outstanding for ackLeft > 0 { |