The main purpose of this is to set an upper bound on the rate at which
an attacker might execute a brute force attack on the weave password.
No need to get clever or precise here.
Closes#837.
The delay d(n) for the nth retry was
d(1) = rand(initial_interval)
d(n+1) = d(n) + rand(d(n))
There are two problem with this:
1) The entire sequence is dominated by the random value for d(1). If
this is a small value, lots of retries at short interval ensue. In
extremis, if d(1) is 0, indefinite immediate retries would ensue.
2) The delay is not a true exponential backoff; the upper bound only
increases exponentially *probabilistically*.
The new algorithm calculates
d(n) = random_value in range [i-i/2,i+i/2],
where i = initial_interval * 1.5^(n-1).
Thus d(1) is at least initial_interval/2, and successive values are
independent of previous values, forming a true exponential sequence of
intervals bounds between which the retry delay is chosen randomly.
Due to the change in algorithm we reduce...
- the initial interval from 5s to 2s. Recall that previously d(1) was
in the range [0,initial_interval=5s]. It is now [2-2/2=1s,2+2/2=3s].
- the max interval from 10 minutes to 6. Previously, once that was
reached, it would stay exactly there. It is now randomly chosen in
the range [6-6/2=3m,6+6/2=9min].
Thus previously delays would range from 0 to 10 minutes, now they
range from 1s to 9 minutes.
Fixes#412.
From the golang spec: 'A "break" statement terminates execution of the
innermost "for", "switch", or "select" statement within the same
function.' But the LocalConnection actorLoop seems to assume it
skips the "select" and terminates the enclosing "for".
As a result, if something did conn.Shutdown(nil), it would not actually
shutdown the connection. It turns out this is never a problem, because
Shutdown is always called with a non-nil error, even though there is code
in a few places to handle the nil case. By cleaning that up, the dubious
"break" is eliminated.
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.
- get rid of individual Peer locks
- hold Peers read (or write) lock and LocalPeer read lock while
performing route calculations
This eliminates the deadlock resulting from the inconsistent lock
acquisition order in route calculcation.
Fixes#643.
This makes for a more symmetric API - Peers.FetchWithDefault does the
increment and Peers.Dereference does the decrement, whereas previously
the latter was done by Peer.DecrementLocalRefCount.
This does increase lock granularity, i.e. modifying any ref count now
requires a write lock on Peers.
When we want a string representation of a Peer, we nearly always just
want the full name. So make String() return that and introduce Info()
to return expanded info.
Matthias Radestock