if a.nNew == 0 -> pickFromOldBucket=true, but we don't have enough items
  (a.nOld > len(oldBucketToAddrsMap) false)

There are cases where we only have a small number of addresses marked
good ("old"), but the selection mechanism keeps trying to select more of these
addresses, and hence ends up in an infinite loop. Here we fix this to
only try and select such "old" addresses if we have enough of them. Note this
means, if we don't have enough of them, we may return more "new"
addresses than otherwise expected by the newSelectionBias.

This whole GetSelectionWithBias method probably needs to be rewritten,
but this is a quick fix for the issue.

As per conversation here: https://github.com/tendermint/tendermint/pull/3218#discussion_r251364041

This is the result of running the following code on the repo:

```bash
find . -name '*.go' | grep -v 'vendor/' | xargs -n 1 goimports -w
```

Closes #3037

* close peer's connection to avoid fd leak

Fixes #2967

* rename peer#Addr to RemoteAddr

* fix test

* fixes after Ethan's review

* bring back the check

* changelog entry

* write a test for switch#acceptRoutine

* increase timeouts? :(

* remove extra assertNPeersWithTimeout

* simplify test

* assert number of peers (just to be safe)

* Cleanup in OnStop

* run tests with verbose flag on CircleCI

* spawn a reading routine to prevent connection from closing

* get port from the listener

random port is faster, but often results in

```
panic: listen tcp 127.0.0.1:44068: bind: address already in use [recovered]
        panic: listen tcp 127.0.0.1:44068: bind: address already in use

goroutine 79 [running]:
testing.tRunner.func1(0xc0001bd600)
        /usr/local/go/src/testing/testing.go:792 +0x387
panic(0x974d20, 0xc0001b0500)
        /usr/local/go/src/runtime/panic.go:513 +0x1b9
github.com/tendermint/tendermint/p2p.MakeSwitch(0xc0000f42a0, 0x0, 0x9fb9cc, 0x9, 0x9fc346, 0xb, 0xb42128, 0x0, 0x0, 0x0, ...)
        /home/vagrant/go/src/github.com/tendermint/tendermint/p2p/test_util.go:182 +0xa28
github.com/tendermint/tendermint/p2p.MakeConnectedSwitches(0xc0000f42a0, 0x2, 0xb42128, 0xb41eb8, 0x4f1205, 0xc0001bed80, 0x4f16ed)
        /home/vagrant/go/src/github.com/tendermint/tendermint/p2p/test_util.go:75 +0xf9
github.com/tendermint/tendermint/p2p.MakeSwitchPair(0xbb8d20, 0xc0001bd600, 0xb42128, 0x2f7, 0x4f16c0)
        /home/vagrant/go/src/github.com/tendermint/tendermint/p2p/switch_test.go:94 +0x4c
github.com/tendermint/tendermint/p2p.TestSwitches(0xc0001bd600)
        /home/vagrant/go/src/github.com/tendermint/tendermint/p2p/switch_test.go:117 +0x58
testing.tRunner(0xc0001bd600, 0xb42038)
        /usr/local/go/src/testing/testing.go:827 +0xbf
created by testing.(*T).Run
        /usr/local/go/src/testing/testing.go:878 +0x353
exit status 2
FAIL    github.com/tendermint/tendermint/p2p    0.350s
```

* Revert to using defers in addrbook.  ValidateBasic->Validate since it requires DNS

* Update CHANGELOG_PENDING

* p2p/conn: FlushStop. Use in pex. Closes #2092

In seed mode, we call StopPeer immediately after Send.
Since flushing msgs to the peer happens in the background,
the peer connection is often closed before the messages are
actually sent out. The new FlushStop method allows all msgs
to first be written and flushed out on the conn before it is closed.

* fix dummy peer

* typo

* fixes from review

* more comments

* ensure pex doesn't call FlushStop more than once

FlushStop is not safe to call more than once,
but we call it from Receive in a go-routine so Receive
doesn't block.

To ensure we only call it once, we use the lastReceivedRequests
map - if an entry already exists, then FlushStop should already have
been called and we can return.

* use READ lock/unlock in ConsensusState#GetLastHeight

Refs #2721

* do not use defers when there's no need

* fix peer formatting (output its address instead of the pointer)

```
[54310]: E[11-02|11:59:39.851] Connection failed @ sendRoutine              module=p2p peer=0xb78f00 conn=MConn{74.207.236.148:26656} err="pong timeout"
```

https://github.com/tendermint/tendermint/issues/2721#issuecomment-435326581

* panic if peer has no state

https://github.com/tendermint/tendermint/issues/2721#issuecomment-435347165

It's confusing that sometimes we check if peer has a state, but most of
the times we expect it to be there

1. add79700b5/mempool/reactor.go (L138)
2. add79700b5/rpc/core/consensus.go (L196) (edited)

I will change everything to always assume peer has a state and panic
otherwise

that should help identify issues earlier

* abci/localclient: extend lock on app callback

App callback should be protected by lock as well (note this was already
done for InitChainAsync, why not for others???). Otherwise, when we
execute the block, tx might come in and call the callback in the same
time we're updating it in execBlockOnProxyApp => DATA RACE

Fixes #2721

Consensus state is locked

```
goroutine 113333 [semacquire, 309 minutes]:
sync.runtime_SemacquireMutex(0xc00180009c, 0xc0000c7e00)
        /usr/local/go/src/runtime/sema.go:71 +0x3d
sync.(*RWMutex).RLock(0xc001800090)
        /usr/local/go/src/sync/rwmutex.go:50 +0x4e
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).GetRoundState(0xc001800000, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:218 +0x46
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusReactor).queryMaj23Routine(0xc0017def80, 0x11104a0, 0xc0072488f0, 0xc007248
9c0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/reactor.go:735 +0x16d
created by github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusReactor).AddPeer
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/reactor.go:172 +0x236
```

because localClient is locked

```
goroutine 1899 [semacquire, 309 minutes]:
sync.runtime_SemacquireMutex(0xc00003363c, 0xc0000cb500)
        /usr/local/go/src/runtime/sema.go:71 +0x3d
sync.(*Mutex).Lock(0xc000033638)
        /usr/local/go/src/sync/mutex.go:134 +0xff
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client.(*localClient).SetResponseCallback(0xc0001fb560, 0xc007868540)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client/local_client.go:32 +0x33
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy.(*appConnConsensus).SetResponseCallback(0xc00002f750, 0xc007868540)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy/app_conn.go:57 +0x40
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state.execBlockOnProxyApp(0x1104e20, 0xc002ca0ba0, 0x11092a0, 0xc00002f750, 0xc0001fe960, 0xc000bfc660, 0x110cfe0, 0xc000090330, 0xc9d12, 0xc000d9d5a0, ...)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state/execution.go:230 +0x1fd
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state.(*BlockExecutor).ApplyBlock(0xc002c2a230, 0x7, 0x0, 0xc000eae880, 0x6, 0xc002e52c60, 0x16, 0x1f927, 0xc9d12, 0xc000d9d5a0, ...)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/state/execution.go:96 +0x142
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).finalizeCommit(0xc001800000, 0x1f928)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1339 +0xa3e
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).tryFinalizeCommit(0xc001800000, 0x1f928)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1270 +0x451
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).enterCommit.func1(0xc001800000, 0x0, 0x1f928)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1218 +0x90
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).enterCommit(0xc001800000, 0x1f928, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1247 +0x6b8
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).addVote(0xc001800000, 0xc003d8dea0, 0xc000cf4cc0, 0x28, 0xf1, 0xc003bc7ad0, 0xc003bc7b10)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1659 +0xbad
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).tryAddVote(0xc001800000, 0xc003d8dea0, 0xc000cf4cc0, 0x28, 0xf1, 0xf1, 0xf1)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:1517 +0x59
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).handleMsg(0xc001800000, 0xd98200, 0xc0070dbed0, 0xc000cf4cc0, 0x28)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:660 +0x64b
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).receiveRoutine(0xc001800000, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:617 +0x670
created by github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus.(*ConsensusState).OnStart
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/consensus/state.go:311 +0x132
```

tx comes in and CheckTx is executed right when we execute the block

```
goroutine 111044 [semacquire, 309 minutes]:
sync.runtime_SemacquireMutex(0xc00003363c, 0x0)
        /usr/local/go/src/runtime/sema.go:71 +0x3d
sync.(*Mutex).Lock(0xc000033638)
        /usr/local/go/src/sync/mutex.go:134 +0xff
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client.(*localClient).CheckTxAsync(0xc0001fb0e0, 0xc002d94500, 0x13f, 0x280, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/abci/client/local_client.go:85 +0x47
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy.(*appConnMempool).CheckTxAsync(0xc00002f720, 0xc002d94500, 0x13f, 0x280, 0x1)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/proxy/app_conn.go:114 +0x51
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/mempool.(*Mempool).CheckTx(0xc002d3a320, 0xc002d94500, 0x13f, 0x280, 0xc0072355f0, 0x0, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/mempool/mempool.go:316 +0x17b
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/core.BroadcastTxSync(0xc002d94500, 0x13f, 0x280, 0x0, 0x0, 0x0)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/core/mempool.go:93 +0xb8
reflect.Value.call(0xd85560, 0x10326c0, 0x13, 0xec7b8b, 0x4, 0xc00663f180, 0x1, 0x1, 0xc00663f180, 0xc00663f188, ...)
        /usr/local/go/src/reflect/value.go:447 +0x449
reflect.Value.Call(0xd85560, 0x10326c0, 0x13, 0xc00663f180, 0x1, 0x1, 0x0, 0x0, 0xc005cc9344)
        /usr/local/go/src/reflect/value.go:308 +0xa4
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server.makeHTTPHandler.func2(0x1102060, 0xc00663f100, 0xc0082d7900)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server/handlers.go:269 +0x188
net/http.HandlerFunc.ServeHTTP(0xc002c81f20, 0x1102060, 0xc00663f100, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:1964 +0x44
net/http.(*ServeMux).ServeHTTP(0xc002c81b60, 0x1102060, 0xc00663f100, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:2361 +0x127
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server.maxBytesHandler.ServeHTTP(0x10f8a40, 0xc002c81b60, 0xf4240, 0x1102060, 0xc00663f100, 0xc0082d7900)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server/http_server.go:219 +0xcf
github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server.RecoverAndLogHandler.func1(0x1103220, 0xc00121e620, 0xc0082d7900)
        /root/go/src/github.com/MinterTeam/minter-go-node/vendor/github.com/tendermint/tendermint/rpc/lib/server/http_server.go:192 +0x394
net/http.HandlerFunc.ServeHTTP(0xc002c06ea0, 0x1103220, 0xc00121e620, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:1964 +0x44
net/http.serverHandler.ServeHTTP(0xc001a1aa90, 0x1103220, 0xc00121e620, 0xc0082d7900)
        /usr/local/go/src/net/http/server.go:2741 +0xab
net/http.(*conn).serve(0xc00785a3c0, 0x11041a0, 0xc000f844c0)
        /usr/local/go/src/net/http/server.go:1847 +0x646
created by net/http.(*Server).Serve
        /usr/local/go/src/net/http/server.go:2851 +0x2f5
```

* consensus: use read lock in Receive#VoteMessage

* use defer to unlock mutex because application might panic

* use defer in every method of the localClient

* add a changelog entry

* drain channels before Unsubscribe(All)

Read 55362ed766/libs/pubsub/pubsub.go (L13)
for the detailed explanation of the issue.

We'll need to fix it someday. Make sure to keep an eye on
https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-033-pubsub.md

* retry instead of panic when peer has no state in reactors other than consensus

in /dump_consensus_state RPC endpoint, skip a peer with no state

* rpc/core/mempool: simplify error messages

* rpc/core/mempool: use time.After instead of timer

also, do not log DeliverTx result (to be consistent with other memthods)

* unlock before calling the callback in reqRes#SetCallback

* Require addressbook to only store addresses with valid ID

* Do not shut down peer immediately after sending pex addrs in SeedMode

* p2p: fix #2773

* seed mode: use go-routine to sleep before stopping peer

* validate reactor messages

Refs #2683

* validate blockchain messages

Refs #2683

* validate evidence messages

Refs #2683

* todo

* check ProposalPOL and signature sizes

* add a changelog entry

* check addr is valid when we add it to the addrbook

* validate incoming netAddr (not just nil check!)

* fixes after Bucky's review

* check timestamps

* beef up block#ValidateBasic

* move some checks into bcBlockResponseMessage

* update Gopkg.lock

Fix

```
grouped write of manifest, lock and vendor: failed to export github.com/tendermint/go-amino: fatal: failed to unpack tree object 6dcc6ddc14
```

by running `dep ensure -update`

* bump year since now we check it

* generate test/p2p/data on the fly using tendermint testnet

* allow sync chains older than 1 year

* use full path when creating a testnet

* move testnet gen to test/docker/Dockerfile

* relax LastCommitRound check

Refs #2737

* fix conflicts after merge

* add small comment

* some ValidateBasic updates

* fixes

* AppHash length is not fixed

* p2p: bring back OriginalAddr

* p2p: set OriginalAddr

* update changelog

* p2p: NodeInfo is an interface

* (squash) fixes from review

* (squash) more fixes from review

* p2p: remove peerConn.HandshakeTimeout

* p2p: NodeInfo is two interfaces. Remove String()

* fixes from review

* remove test code from peer.RemoteIP()

* p2p: remove peer.OriginalAddr(). See #2618

* use a mockPeer in peer_set_test.go

* p2p: fix testNodeInfo naming

* p2p: remove unused var

* remove testRandNodeInfo

* fix linter

* fix retry dialing self

* fix rpc

We are swapping the exisiting listener implementation with the newly
introduced Transport and its default implementation MultiplexTransport,
removing a large chunk of old connection setup and handling scattered
over the Peer and Switch code. The Switch requires a Transport now and
handles externally passed Peer filters.

* ignore existing peers in DialPeersAsync

Fixes #2253

* rename HasPeerWithAddress to IsDialingOrExistingAddress

[breaking] remove Switch#IsDialing

* check if addrBook is nil

to be consistent with other usages of addrBook across Switch

* different log messages for 2 use-cases

* [p2p/pex] connect to more than 10 peers

also, remove DefaultMinNumOutboundPeers because a) I am not sure it's
needed b) it's super confusing

look closely

```
maxPeers := sw.config.MaxNumPeers - DefaultMinNumOutboundPeers
if maxPeers <= sw.peers.Size() {
  sw.Logger.Info("Ignoring inbound connection: already have enough peers", "address", inConn.RemoteAddr().String(), "numPeers", sw.peers.Size(), "max", maxPeers)
```

we print maxPeers = config.MaxPeers - DefaultMinNumOutboundPeers. So we
may not have enough peers even though we say we have enough.

Refs #2130

* update spec

* replace MaxNumPeers with MaxNumInboundPeers/MaxNumOutboundPeers

Refs #2130

* update changelog

* make max rpc conns formula visible to users

* update spec

* docs: note max outbound peers excludes persistent

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

Closes #2193

* Fix bug that was masked by custom Fmt!

* p2p/pex: Allow configured seed nodes to be offline

Previously you couldn't startup tendermint if a seed node was offline.
This now allows you to startup tendermint, as long as all seed node addresses
are formatted correctly. In the event that all seed nodes are down,
and the address book is empty, then it crashes with an informative error msg.
(This case doesn't occur if no seeds were specified)

Closes #1716

* (Squash this) Address melekes' comments

* (squash this) fix package imports

* (squash this) fix pex_reactor comment

* (squash this) add a test case

also, remove excessive log message

Refs #2072

This is to reduce wait times when initially connecting. This still runs checks
such as whether you still want additional peers.

A test case has been created, which fails if this change is not included.

* Removed unnecessary onStart & onStop calls in reactor

* Refactor OnStart & OnStop in reactor

* Removed redundant OnStart func in reactor

Refs #1706

Currently the top level directory contains basically all of the code
for the crypto package. This PR moves the crypto code into submodules
in a similar manner to what `golang/x/crypto` does. This improves code
organization.

Ref discussion: https://github.com/tendermint/tendermint/pull/1966

Closes #1956

Refs #1720

* Add private peer ID tracking to AddrBook

* Remove private peer tracking/blocking from pex

* debug level msg when we fail to add private address

This commit switches all usage of math/rand to cmn's rand. The only
exceptions are within the random file itself, the tools package, and the
crypto package. In tools you don't want it to lock between the go-routines.
The crypto package doesn't use it so the crypto package have no other
dependencies within tendermint/tendermint for easier portability.

Crypto/rand usage is unadjusted.

Closes #1343

This reverts commit d02c5d1e30.

Refs #646

Refs #646

* new config option for external address to advertise
* if blank, defaults to best guess from listener
* if laddr ip address is also blank, default to IPv4

Fixes #1830

remember that PeerSet#Get can return nil

* config: rename skip_upnp to upnp

Change default option to enable upnp.

Closes #1806

* doc updates

- fix comment and set UPNP to false in TestP2PConfig
- add UPNP to config template
- update changelog

This reverts commit 96a3502

As both configs are concerned with the p2p packaage and PeerConfig is
only used inside of the package there is no good reason to keep the
couple of fields separate, therefore it is collapsed into the more
general P2PConifg. This is a stepping stone towards a setup where the
components inside of p2p do not have any knowledge about the config.

follow-up to #1325

In some scenarios like tests we want to disable the guard which prevents
peers connecting from the same ip.

Fixes #1632
Closes #1634