This introduces interfaces to represent the packet forwarding
mechanism, and brings all the scattered UDP-related code together into
a single implementation.
This is not a pure refactoring, although much of the code in sleeve.go
has been copied from pre-existing code, and the UDP protocol remains
the same in spirit. The biggest change is the organization of the
forwarder goroutines (there is now one instead of two, and that
goroutine does a lot of auxiliary work as well as forwarding).
Performance testing between VMs on my laptop suggests that packet
throughput has not gone down, and may even have improved slightly.
To allow users to forgo compatibility with Weave Net 1.0 in order to
avoid #912, by setting --protocol-min-version=2.
Defaults to --protocol-min-version=1, i.e. compatible but vulnerable.
We now first exchange a very minimal header, consisting of just the
name of the protocol ("weave") and the min and max version (encoded as
a byte each) we support. This leaves all other details of the
protocol, including the contents of of the handshake, open.
Peers agree to communicate using the maximum mutually supported
version. We record this in the LocalConnection, though atm nothing is
making use of that information.
We set a shorter than normal deadline (10s instead of 60s) for the
header exchange, so we detect version mismatches, garbage, or
non-responsive remotes quickly.
We reset the protocol version to '1' since this is a fresh start; old
weaves will not be able to parse the header.
Closes#871.
This is how fragmentation tests used to happen:
A: conn.stackFrag = false
A->B: StartFragmentationTest
B->A: send large non-DF UDP packet
A->B: FragmentationReceived
B: conn.stackFrag = true
conn.stackFrag = true means "UDP packets sent to the other peer get
correctly fragmented and re-assembled".
Note how A clears its own stackFrag flag, but the test establishes
whether fragmentation works for B->A, and ends up setting stackFrag on
B. Not only is this weird, it also means that if A previously had
stackFrag=true, it will now start fragmenting packets until B
initiates a fragmentation test.
The new sequence is:
A: conn.stackFrag = false
A->B: send large non-DF UDP packet
B->A: FragmentationReceived
A: conn.stackFrag = true
Closes#746.
Using the Ring CRDT and Weave gossip, provides an interface
for the weave script to allocate IP addresses in `weave run`,
`weave start` and `weave expose`.
See docs/ipam.md for implementation details, and site/features.md
for user-visible changes.
This was a convenient but rather suspect coupling. In particular, it
will break if the period gossip logic changes s.t. it no longer sends
gossip on all connections every interval.
Topology gossip can be received on a connection before that connection
has been marked as 'established'. If we do not include unestablished
connections in topology gossip, then parts of the topology can be
removed by gc, since they are deemed unreachable, which can cause
subsequent incremental topology gossips to be rejected due to them
containing references to peers that have been removed by the gc.
Including unestablished connections in topology gossip requires:
- removing the check for 'established' connections in the encoding of
peers for topology gossip,
- adding the 'established' flag to the internal representation of
remote connections,
- adding the 'established' flag to to encoding of connections in
topology gossip,
- treating the *addition* of a connection as an update to the local
peer.
The latter entails
- bumping the peer version on connection addition (as well as on
marking 'established' as previously),
- bumping the peer version *unconditionally* on connection deletion
(rather than only when the connection was 'established', as
previously),
- moving the initial sending of complete topology on the connection,
and the broadcasting of a topology update containing the two peers
at the ends of the connection, from the connection 'established'
logic to the connection addition logic,
- broadcasting just an topology update for the local peer when a
connection gets marked as 'established',
- broadcasting a topology update for the local peer *unconditionally*
when a connection is removed (rather than only doing this when the
connection was 'established', as previously).
David Wragg