If a node is offline failed outbound connection attempts will crank up
the addrman counter and effectively blow away our state.
This change reduces the problem by only counting attempts made while
the node believes it has outbound connections to at least two
netgroups.
Connect and addnode connections are also not counted, as there is no
reason to unequally penalize them for their more frequent
connections -- though there should be no real effect from this
unless their addnode configureation is later removed.
Wasteful repeated connection attempts while only a few connections are
up are avoided via nLastTry.
This is still somewhat incomplete protection because our outbound
peers could be down but not timed out or might all be on 'local'
networks (although the requirement for multiple netgroups helps).
The ability to GETDATA a transaction which has not (yet) been relayed
is a privacy loss vector.
The use of the mempool for this was added as part of the mempool p2p
message and is only needed to fetch transactions returned by it.
The current logic for syncing headers may lead to lots of duplicate
getheaders requests being sent: If a new block arrives while the node
is in headers sync, it will send getheaders in response to the block
announcement. When the headers arrive, the message will be of maximum
size and so a follow-up request will be sent---all of that in addition
to the existing headers syncing. This will create a second "chain" of
getheaders requests. If more blocks arrive, this may even lead to
arbitrarily many parallel chains of redundant requests.
This patch changes the behaviour to only request more headers after a
maximum-sized message when it contained at least one unknown header.
This avoids sustaining parallel chains of redundant requests.
Note that this patch avoids the issues raised in the discussion of
https://github.com/bitcoin/bitcoin/pull/6821: There is no risk of the
node being permanently blocked. At the latest when a new block arrives
this will trigger a new getheaders request and restart syncing.
Verify that results correct (match known values), consistent (encrypt->decrypt
matches the original), and compatible with the previous openssl implementation.
Also check that failed encrypts/decrypts fail the exact same way as openssl.
Wallet must come before crypto, otherwise linking fails on some platforms.
Includes a tangentially-related general cleanup rather than making the Makefile
sloppier.
The output should always match openssl's, even for failed operations. Even for
a decrypt with broken padding, the output is always deterministic (and attemtps
to be constant-time).
Pieter Wuille