7a8c251901 made this logic hard to follow. After that change, messages would
not be sent to a peer via SendMessages() before the handshake was complete, but
messages could still be sent as a response to an incoming message.
For example, if a peer had not yet sent a verack, we wouldn't notify it about
new blocks, but we would respond to a PING with a PONG.
This change makes the behavior straightforward: until we've received a verack,
never send any message other than version/verack/reject.
The behavior until a VERACK is received has always been undefined, this change
just tightens our policy.
This also makes testing much easier, because we can now connect but not send
version/verack, and anything sent to us is an error.
Prior to this change, all messages were ignored until a VERSION message was
received, as well as possibly incurring a ban score.
Since REJECT messages can be sent at any time (including as a response to a bad
VERSION message), make sure to always parse them.
Moving this parsing up keeps it from being caught in the
if (pfrom->nVersion == 0) check below.
7a8c251901 made a change to avoid getting into SendMessages() until the
version handshake (VERSION + VERACK) is complete. That was done to avoid
leaking out messages to nodes who could connect, but never bothered sending
us their version/verack.
Unfortunately, the ban tally and possible disconnect are done as part of
SendMessages(). So after 7a8c251901, if a peer managed to do something
bannable before completing the handshake (say send 100 non-version messages
before their version), they wouldn't actually end up getting
disconnected/banned. That's fixed here by checking the banscore as part of
ProcessMessages() in addition to SendMessages().
These are (afaik) all long-standing races or concurrent accesses. Going
forward, we can clean these up so that they're not all individual atomic
accesses.
- Reintroduce cs_vRecv to guard receive-specific vars
- Lock vRecv/vSend for CNodeStats
- Make some vars atomic.
- Only set the connection time in CNode's constructor so that it doesn't change
0729102 Net: pass interruptMsgProc as const where possible (Jorge Timón)
fc7f2ff Net: Make CNetMsgMaker more const (Jorge Timón)
d45955f Net: CConnman: Make some methods const (Jorge Timón)
This avoids having some vars set if the version negotiation fails.
Also copy it all into CNode at the same site. nVersion and
fSuccessfullyConnected are set last, as they are the gates for the other vars.
Make them atomic for that reason.
This adds a comment to the new logic for setting HB peers based
on block validation (and aligns the code below to reflect the comment).
It's not obvious why we're checking mapBlocksInFlight. Add a comment to
explain.
The old Bitcoin alert system has long since been retired.
( See also: https://bitcoin.org/en/alert/2016-11-01-alert-retirement )
This change causes each node to send any old peers that
it connects with a copy of the final alert.
The alert it hardcode cancels all other alerts including
other final alerts.
This forces the message handling thread to make another full
iteration of SendMessages prior to going back to sleep, ensuring
we announce the new block to all peers before sleeping.
02ee4eb Make most_recent_compact_block a pointer to a const (Matt Corallo)
73666ad Add comment to describe callers to ActivateBestChain (Matt Corallo)
962f7f0 Call ActivateBestChain without cs_main/with most_recent_block (Matt Corallo)
0df777d Use a temp pindex to avoid a const_cast in ProcessNewBlockHeaders (Matt Corallo)
c1ae4fc Avoid holding cs_most_recent_block while calling ReadBlockFromDisk (Matt Corallo)
9eb67f5 Ensure we meet the BIP 152 old-relay-types response requirements (Matt Corallo)
5749a85 Cache most-recently-connected compact block (Matt Corallo)
9eaec08 Cache most-recently-announced block's shared_ptr (Matt Corallo)
c802092 Relay compact block messages prior to full block connection (Matt Corallo)
6987219 Add a CValidationInterface::NewPoWValidBlock callback (Matt Corallo)
180586f Call AcceptBlock with the block's shared_ptr instead of CBlock& (Matt Corallo)
8baaba6 [qa] Avoid race in preciousblock test. (Matt Corallo)
9a0b2f4 [qa] Make compact blocks test construction using fetch methods (Matt Corallo)
8017547 Make CBlockIndex*es in net_processing const (Matt Corallo)
e60360e net: remove cs_vRecvMsg (Cory Fields)
991955e net: add a flag to indicate when a node's send buffer is full (Cory Fields)
c6e8a9b net: add a flag to indicate when a node's process queue is full (Cory Fields)
4d712e3 net: add a new message queue for the message processor (Cory Fields)
c5a8b1b net: rework the way that the messagehandler sleeps (Cory Fields)
c72cc88 net: remove useless comments (Cory Fields)
ef7b5ec net: Add a simple function for waking the message handler (Cory Fields)
f5c36d1 net: record bytes written before notifying the message processor (Cory Fields)
60befa3 net: handle message accounting in ReceiveMsgBytes (Cory Fields)
56212e2 net: set message deserialization version when it's actually time to deserialize (Cory Fields)
0e973d9 net: remove redundant max sendbuffer size check (Cory Fields)
6042587 net: wait until the node is destroyed to delete its recv buffer (Cory Fields)
f6315e0 net: only disconnect if fDisconnect has been set (Cory Fields)
5b4a8ac net: make GetReceiveFloodSize public (Cory Fields)
e5bcd9c net: make vRecvMsg a list so that we can use splice() (Cory Fields)
53ad9a1 net: fix typo causing the wrong receive buffer size (Cory Fields)
vRecvMsg is now only touched by the socket handler thread.
The accounting vars (nRecvBytes/nLastRecv/mapRecvBytesPerMsgCmd) are also
only used by the socket handler thread, with the exception of queries from
rpc/gui. These accesses are not threadsafe, but they never were. This needs to
be addressed separately.
Also, update comment describing data flow
Similar to the recv flag, but this one indicates whether or not the net's send
buffer is full.
The socket handler checks the send queue when a new message is added and pauses
if necessary, and possibly unpauses after each message is drained from its buffer.
Messages are dumped very quickly from the socket handler to the processor, so
it's the depth of the processing queue that's interesting.
The socket handler checks the process queue's size during the brief message
hand-off and pauses if necessary, and the processor possibly unpauses each time
a message is popped off of its queue.
In order to sleep accurately, the message handler needs to know if _any_ node
has more processing that it should do before the entire thread sleeps.
Rather than returning a value that represents whether ProcessMessages
encountered a message that should trigger a disconnnect, interpret the return
value as whether or not that node has more work to do.
Also, use a global fProcessWake value that can be set by other threads,
which takes precedence (for one cycle) over the messagehandler's decision.
Note that the previous behavior was to only process one message per loop
(except in the case of a bad checksum or invalid header). That was changed in
PR #3180.
The only change here in that regard is that the current node now falls to the
back of the processing queue for the bad checksum/invalid header cases.
There is still a call to ActivateBestChain with cs_main if a peer
requests the block prior to it being validated, but this one is
more specifically-gated, so should be less of an issue.
Previously addnodes were in competition with outbound connections
for access to the eight outbound slots.
One result of this is that frequently a node with several addnode
configured peers would end up connected to none of them, because
while the addnode loop was in its two minute sleep the automatic
connection logic would fill any free slots with random peers.
This is particularly unwelcome to users trying to maintain links
to specific nodes for fast block relay or purposes.
Another result is that a group of nine or more nodes which are
have addnode configured towards each other can become partitioned
from the public network.
This commit introduces a new limit of eight connections just for
addnode peers which is not subject to any of the other connection
limitations (including maxconnections).
The choice of eight is sufficient so that under no condition would
a user find themselves connected to fewer addnoded peers than
previously. It is also low enough that users who are confused
about the significance of more connections and have gotten too
copy-and-paste happy will not consume more than twice the slot
usage of a typical user.
Any additional load on the network resulting from this will likely
be offset by a reduction in users applying even more wasteful
workaround for the prior behavior.
The retry delays are reduced to avoid nodes sitting around without
their added peers up, but are still sufficient to prevent overly
aggressive repeated connections. The reduced delays also make
the system much more responsive to the addnode RPC.
Ban-disconnects are also exempted for peers added via addnode since
the outbound addnode logic ignores bans. Previously it would ban
an addnode then immediately reconnect to it.
A minor change was also made to CSemaphoreGrant so that it is
possible to re-acquire via an object whos grant was moved.
In order to do this, we must call ActivateBestChain prior to
responding getdata requests for blocks which we announced using
compact blocks.
For getheaders responses we dont need code changes, but do note
that we must reset the bestHeaderSent so that the SendMessages call
re-announces the header in question.
While we could do something smarter for getblocks, calling
ActivateBestChain is simple and more obviously correct, instead of
doing something more similar to getheaders.
See-also the BIP clarifications at
https://github.com/bitcoin/bips/pull/486
813ede9 [qa] Update compactblocks test for multi-peer reconstruction (Suhas Daftuar)
7017298 Allow compactblock reconstruction when block is in flight (Suhas Daftuar)
dd0df81 Document ConnectBlock connectTrace postconditions (Matt Corallo)
2d6e561 Switch pblock in ProcessNewBlock to a shared_ptr (Matt Corallo)
2736c44 Make the optional pblock in ActivateBestChain a shared_ptr (Matt Corallo)
ae4db44 Create a shared_ptr for the block we're connecting in ActivateBCS (Matt Corallo)
fd9d890 Keep blocks as shared_ptrs, instead of copying txn in ConnectTip (Matt Corallo)
6fdd43b Add struct to track block-connect-time-generated info for callbacks (Matt Corallo)
