Earlier this week somebody posted this in GoS Riot chat:

```
E[2019-02-12|10:38:37.596] Corrupted entry. Skipping... module=consensus wal=/home/gaia/.gaiad/data/cs.wal/wal err="DataCorruptionError[length 878916964 exceeded maximum possible value of 1048576 bytes]"
E[2019-02-12|10:38:37.596] Corrupted entry. Skipping... module=consensus wal=/home/gaia/.gaiad/data/cs.wal/wal err="DataCorruptionError[length 825701731 exceeded maximum possible value of 1048576 bytes]"
E[2019-02-12|10:38:37.596] Corrupted entry. Skipping... module=consensus wal=/home/gaia/.gaiad/data/cs.wal/wal err="DataCorruptionError[length 1631073634 exceeded maximum possible value of 1048576 bytes]"
E[2019-02-12|10:38:37.596] Corrupted entry. Skipping... module=consensus wal=/home/gaia/.gaiad/data/cs.wal/wal err="DataCorruptionError[length 912418148 exceeded maximum possible value of 1048576 bytes]"
E[2019-02-12|10:38:37.600] Corrupted entry. Skipping... module=consensus wal=/home/gaia/.gaiad/data/cs.wal/wal err="DataCorruptionError[failed to read data: EOF]"
E[2019-02-12|10:38:37.600] Error on catchup replay. Proceeding to start ConsensusState anyway module=consensus err="Cannot replay height 7242. WAL does not contain #ENDHEIGHT for 7241"
E[2019-02-12|10:38:37.861] Error dialing peer module=p2p err="dial tcp 35.183.126.181:26656: i/o timeout
```

Note the length error messages. What has happened is the length field got corrupted probably. I've looked at the code and noticed that we don't check the msg size during encoding. This PR fixes that. It also improves a few error messages in WALDecoder.

Should fix #3295
Also partial fix of #3043

* node: decrease retry conn timeout in test

Should fix #3256

The retry timeout was set to the default, which is the same as the
accept timeout, so it's no wonder this would fail. Here we decrease the
retry timeout so we can try many times before the accept timeout.

* p2p: increase handshake timeout in test

This fails sometimes, presumably because the handshake timeout is so low
(only 50ms). So increase it to 1s. Should fix #3187

* privval: fix race with ping. closes #3237

Pings happen in a go-routine and can happen concurrently with other
messages. Since we use a request/response protocol, we expect to send a
request and get back the corresponding response. But with pings
happening concurrently, this assumption could be violated. We were using
a mutex, but only a RWMutex, where the RLock was being held for sending
messages - this was to allow the underlying connection to be replaced if
it fails. Turns out we actually need to use a full lock (not just a read
lock) to prevent multiple requests from happening concurrently.

* node: fix test name. DelayedStop -> DelayedStart

* autofile: Wait() method

In the TestWALTruncate in consensus/wal_test.go we remove the WAL
directory at the end of the test. However the wal.Stop() does not
properly wait for the autofile group to finish shutting down. Hence it
was possible that the group's go-routine is still running when the
cleanup happens, which causes a panic since the directory disappeared.
Here we add a Wait() method to properly wait until the go-routine exits
so we can safely clean up. This fixes #2852.

* privval: more info in errors

* wal: change Debug logs to Info

* wal: log and return error on corrupted wal instead of panicing

* fail: Exit right away instead of sending interupt

* consensus: FAIL before handling our own vote

allows to replicate #3089:
- run using `FAIL_TEST_INDEX=0`
- delete some bytes from the end of the WAL
- start normally

Results in logs like:

```
I[2019-02-03|18:12:58.225] Searching for height module=consensus wal=/Users/ethanbuchman/.tendermint/data/cs.wal/wal height=1 min=0 max=0
E[2019-02-03|18:12:58.225] Error on catchup replay. Proceeding to start ConsensusState anyway module=consensus err="failed to read data: EOF"
I[2019-02-03|18:12:58.225] Started node module=main nodeInfo="{ProtocolVersion:{P2P:6 Block:9 App:1} ID_:35e87e93f2e31f305b65a5517fd2102331b56002 ListenAddr:tcp://0.0.0.0:26656 Network:test-chain-J8JvJH Version:0.29.1 Channels:4020212223303800 Moniker:Ethans-MacBook-Pro.local Other:{TxIndex:on RPCAddress:tcp://0.0.0.0:26657}}"
E[2019-02-03|18:12:58.226] Couldn't connect to any seeds module=p2p
I[2019-02-03|18:12:59.229] Timed out module=consensus dur=998.568ms height=1 round=0 step=RoundStepNewHeight
I[2019-02-03|18:12:59.230] enterNewRound(1/0). Current: 1/0/RoundStepNewHeight module=consensus height=1 round=0
I[2019-02-03|18:12:59.230] enterPropose(1/0). Current: 1/0/RoundStepNewRound module=consensus height=1 round=0
I[2019-02-03|18:12:59.230] enterPropose: Our turn to propose module=consensus height=1 round=0 proposer=AD278B7767B05D7FBEB76207024C650988FA77D5 privValidator="PrivValidator{AD278B7767B05D7FBEB76207024C650988FA77D5 LH:1, LR:0, LS:2}"
E[2019-02-03|18:12:59.230] enterPropose: Error signing proposal module=consensus height=1 round=0 err="Error signing proposal: Step regression at height 1 round 0. Got 1, last step 2"
I[2019-02-03|18:13:02.233] Timed out module=consensus dur=3s height=1 round=0 step=RoundStepPropose
I[2019-02-03|18:13:02.233] enterPrevote(1/0). Current: 1/0/RoundStepPropose module=consensus
I[2019-02-03|18:13:02.233] enterPrevote: ProposalBlock is nil module=consensus height=1 round=0
E[2019-02-03|18:13:02.234] Error signing vote module=consensus height=1 round=0 vote="Vote{0:AD278B7767B0 1/00/1(Prevote) 000000000000 000000000000 @ 2019-02-04T02:13:02.233897Z}" err="Error signing vote: Conflicting data"
```

Notice the EOF, the step regression, and the conflicting data.

* wal: change errors to be DataCorruptionError

* exit on corrupt WAL

* fix log

* fix new line

* fix Group.RotateFile need call Flush() before rename. #2428
* fix some review issue. #2428
 refactor Group's config: replace  setting member with initial option
* fix a handwriting mistake
* fix a time window error between rename and write.
* fix a syntax mistake.
* change option name Get_ to With_
* fix review issue
* fix review issue

* remove ConsensusParams.TxSize and ConsensusParams.BlockGossip

Refs #2347

* block part size is now fixed

Refs #2347

* use max data size, not max bytes for tx limit

Refs #2347

* Implement BFT time

* set LastValidators when creating state in state helper

for heights >= 2

* libs: Remove usage of custom Fmt, in favor of fmt.Sprintf

Closes #2193

* Fix bug that was masked by custom Fmt!

This reverts commit d02c5d1e30.

This reverts commit 96a3502

Refs #1659
Refs https://github.com/tendermint/tmlibs/pull/217

Refs #1600

since we never write msg partially, if we've encountered io.EOF in the
middle of the msg, we must abort

i.e., can't be skipped

and we should only return DataCorruptionError if we can skip a msg safely

msg is nil and if we continue executing, we'll get nil exception at
`msg.Msg.(....)`

Closes #1428

otherwise, it is easy to get OutOfMemory panic (somebody can even expoit
this)

Refs #573

to be consistent with Decode, which returns TimedWALMessage

We don't really need a separator unless we have complex structures
(rows, cells like RDBMS have https://www.sqlite.org/fileformat.html).

uint64 is considered dangerous. the details will follow in a blog post.

See https://github.com/tendermint/tmlibs/issues/45

comment out failing consensus tests for now

rewrite rpc httpclient to use new pubsub package

import pubsub as tmpubsub, query as tmquery

make event IDs constants
EventKey -> EventTypeKey

rename EventsPubsub to PubSub

mempool does not use pubsub

rename eventsSub to pubsub

new subscribe API

fix channel size issues and consensus tests bugs

refactor rpc client

add missing discardFromChan method

add mutex

rename pubsub to eventBus

remove IsRunning from WSRPCConnection interface (not needed)

add a comment in broadcastNewRoundStepsAndVotes

rename registerEventCallbacks to broadcastNewRoundStepsAndVotes

See https://dave.cheney.net/2014/03/19/channel-axioms

stop eventBuses after reactor tests

remove unnecessary Unsubscribe

return subscribe helper function

move discardFromChan to where it is used

subscribe now returns an err

this gives us ability to refuse to subscribe if pubsub is at its max
capacity.

use context for control overflow

cache queries

handle err when subscribing in replay_test

rename testClientID to testSubscriber

extract var

set channel buffer capacity to 1 in replay_file

fix byzantine_test

unsubscribe from single event, not all events

refactor httpclient to return events to appropriate channels

return failing testReplayCrashBeforeWriteVote test

fix TestValidatorSetChanges

refactor code a bit

fix testReplayCrashBeforeWriteVote

add comment

fix TestValidatorSetChanges

fixes from Bucky's review

update comment [ci skip]

test TxEventBuffer

update changelog

fix TestValidatorSetChanges (2nd attempt)

only do wg.Done when no errors

benchmark event bus

create pubsub server inside NewEventBus

only expose config params (later if needed)

set buffer capacity to 0 so we are not testing cache

new tx event format: key = "Tx" plus a tag {"tx.hash": XYZ}

This should allow to subscribe to all transactions! or a specific one
using a query: "tm.events.type = Tx and tx.hash = '013ABF99434...'"

use TimeoutCommit instead of afterPublishEventNewBlockTimeout

TimeoutCommit is the time a node waits after committing a block, before
it goes into the next height. So it will finish everything from the last
block, but then wait a bit. The idea is this gives it time to hear more
votes from other validators, to strengthen the commit it includes in the
next block. But it also gives it time to hear about new transactions.

waitForBlockWithUpdatedVals

rewrite WAL crash tests

Task:
test that we can recover from any WAL crash.

Solution:
the old tests were relying on event hub being run in the same thread (we
were injecting the private validator's last signature).

when considering a rewrite, we considered two possible solutions: write
a "fuzzy" testing system where WAL is crashing upon receiving a new
message, or inject failures and trigger them in tests using something
like https://github.com/coreos/gofail.

remove sleep

no cs.Lock around wal.Save

test different cases (empty block, non-empty block, ...)

comments

add comments

test 4 cases: empty block, non-empty block, non-empty block with smaller part size, many blocks

fixes as per Bucky's last review

reset subscriptions on UnsubscribeAll

use a simple counter to track message for which we panicked

also, set a smaller part size for all test cases

change echo format in build.sh script

updated test_data/build.sh script