The JSON-RPC endpoint accepts requests via URL (GET) and JSON (POST).  There is
no real point in having client libraries for both modes.

A search of the SDK and on GitHub suggests that most usage is via the JSON
client (via the New constructor) or websocket (NewWS), and the only uses I
found of the NewURI client constructor are in copies of our own test code.

This does not change the functionalitiy of the server, so curl and other
URL-based clients in other languages will still function as before.

This continues the push of plumbing contexts through tendermint. I
attempted to find all goroutines in the production code (non-test) and
made sure that these threads would exit when their contexts were
canceled, and I believe this PR does that.

The code in the Tendermint repository makes heavy use of import aliasing.
This is made necessary by our extensive reuse of common base package names, and
by repetition of similar names across different subdirectories.

Unfortunately we have not been very consistent about which packages we alias in
various circumstances, and the aliases we use vary. In the spirit of the advice
in the style guide and https://github.com/golang/go/wiki/CodeReviewComments#imports,
his change makes an effort to clean up and normalize import aliasing.

This change makes no API or behavioral changes. It is a pure cleanup intended
o help make the code more readable to developers (including myself) trying to
understand what is being imported where.

Only unexported names have been modified, and the changes were generated and
applied mechanically with gofmt -r and comby, respecting the lexical and
syntactic rules of Go.  Even so, I did not fix every inconsistency. Where the
changes would be too disruptive, I left it alone.

The principles I followed in this cleanup are:

- Remove aliases that restate the package name.
- Remove aliases where the base package name is unambiguous.
- Move overly-terse abbreviations from the import to the usage site.
- Fix lexical issues (remove underscores, remove capitalization).
- Fix import groupings to more closely match the style guide.
- Group blank (side-effecting) imports and ensure they are commented.
- Add aliases to multiple imports with the same base package name.

EDIT: Updated, see [comment below]( https://github.com/tendermint/tendermint/pull/6785#issuecomment-897793175)

This change adds a sketch of the `Debug` mode. 

This change adds a `Debug` struct to the node package. This `Debug` struct is intended to be created and started by a command in the `cmd` directory. The `Debug` struct runs the RPC server on the data directories: both the state store and the block store.

This change required a good deal of refactoring. Namely, a new `rpc.go` file was added to the `node` package. This file encapsulates functions for starting RPC servers used by nodes. A potential additional change is to further factor this code into shared code _in_ the `rpc` package. 

Minor API tweaks were also made that seemed appropriate such as the mechanism for fetching routes from the `rpc/core` package.

Additional work is required to register the `Debug` service as a command in the `cmd` directory but I am looking for feedback on if this direction seems appropriate before diving much further.

closes: #5908

Closes #5145

also applies to light/client

## Description

Enable errcheck linter throughout the codebase

Closes: #5059

## Description

add more error checks to tests


gonna do a third PR that tackles the non test cases

Migrates the `rpc` package to use new JSON encoder in #4955. Branched off of that PR.

Tests pass, but I haven't done any manual testing beyond that. This should be handled as part of broader 0.34 testing.

Closes https://github.com/tendermint/tendermint/issues/3857

Moves `lib/` folder to `jsonrpc/`.

Renames:

**packages**

`rpc` package -> `jsonrpc` package
`rpcclient` package -> `client` package
`rpcserver` package -> `server` package

**structs and interfaces**

```
JSONRPCClient to Client
JSONRPCRequestBatch to RequestBatch
JSONRPCCaller to Caller
```

**functions**

```
StartHTTPServer to Serve
StartHTTPAndTLSServer to ServeTLS

rpc/jsonrpc/client: rename NewURIClient to NewURI

NewJSONRPCClient to New
NewJSONRPCClientWithHTTPClient to NewWithHTTPClient
NewWSClient to NewWS
```

**misc**

- unexpose `ResponseWriterWrapper`
- remove unused http_params.go

* format: add format cmd & goimport repo

- replaced format command
- added goimports to format command
- ran goimports

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* fix outliers & undo proto file changes

The New* client functions return an error instead
of panicking when the remote address is invalid.

Fixes #3953

* lint: golint issue fixes

- on my local machine golint is a lot stricter than the bot so slowly going through and fixing things.

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* more fixes from golint

* remove isPeerPersistentFn

* add changelog entry

* libs/common: Refactor libs/common 4

- move byte function out of cmn to its own pkg
- move tempfile out of cmn to its own pkg
- move throttletimer to its own pkg

ref #4147

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* add changelog entry

* fix linting issues

* libs/common: refactor libs/common 2

- move random function to there own pkg

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* change imports and usage throughout repo

* fix goimports

* add changelog entry

* Fix maligned structs

* Fix interfacer errors

* Revert accidental go.mod and go.sum changes

* Revert P2PConfig struct maligned reorder

* Revert PeerRoundState struct maligned reordering

* Revert RoundState struct maligned reordering

* Reorder WSClient struct

* Revert accidental type change

* Clean up type change

* Clean up type changes

* Revert to types.ABCIApplicationServer in GRPCServer struct

* Revert maligned changes to BaseConfig struct

* Fix tests in io_test.go

* Fix client_test package tests

* Fix reactor tests in consensus package

* Fix new interfacer errors

* Remove unnecessary type conversions

* Consolidate repeated strings into consts

* Clothe return statements

* Update blockchain/v1/reactor_fsm_test.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

This PR repairs linter errors seen when running the following commands:
golangci-lint run --no-config --disable-all=true --enable=unconvert
golangci-lint run --no-config --disable-all=true --enable=goconst
golangci-lint run --no-config --disable-all=true --enable=nakedret

Contributes to #3262

* Make sure config.TimeoutBroadcastTxCommit < rpcserver.WriteTimeout()

* remove redundant comment

* libs/rpc/http_server: move Read/WriteTimeout into Config

* increase defaults for read/write timeouts

Based on this article
https://www.digitalocean.com/community/tutorials/how-to-optimize-nginx-configuration

* WriteTimeout should be larger than TimeoutBroadcastTxCommit

* set a deadline for subscribing to txs

* extract duration into const

* add two changelog entries

* Update CHANGELOG_PENDING.md

Co-Authored-By: melekes <anton.kalyaev@gmail.com>

* Update CHANGELOG_PENDING.md

Co-Authored-By: melekes <anton.kalyaev@gmail.com>

* 12 -> 10

* changelog

* changelog

* limit number of /subscribe clients and queries per client

Add the following config variables (under [rpc] section):
  * max_subscription_clients
  * max_subscriptions_per_client
  * timeout_broadcast_tx_commit

Fixes #2826

new HTTPClient interface for subscriptions

finalize HTTPClient events interface

remove EventSubscriber

fix data race

```
WARNING: DATA RACE
Read at 0x00c000a36060 by goroutine 129:
  github.com/tendermint/tendermint/rpc/client.(*Local).Subscribe.func1()
      /go/src/github.com/tendermint/tendermint/rpc/client/localclient.go:168 +0x1f0

Previous write at 0x00c000a36060 by goroutine 132:
  github.com/tendermint/tendermint/rpc/client.(*Local).Subscribe()
      /go/src/github.com/tendermint/tendermint/rpc/client/localclient.go:191 +0x4e0
  github.com/tendermint/tendermint/rpc/client.WaitForOneEvent()
      /go/src/github.com/tendermint/tendermint/rpc/client/helpers.go:64 +0x178
  github.com/tendermint/tendermint/rpc/client_test.TestTxEventsSentWithBroadcastTxSync.func1()
      /go/src/github.com/tendermint/tendermint/rpc/client/event_test.go:139 +0x298
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:827 +0x162

Goroutine 129 (running) created at:
  github.com/tendermint/tendermint/rpc/client.(*Local).Subscribe()
      /go/src/github.com/tendermint/tendermint/rpc/client/localclient.go:164 +0x4b7
  github.com/tendermint/tendermint/rpc/client.WaitForOneEvent()
      /go/src/github.com/tendermint/tendermint/rpc/client/helpers.go:64 +0x178
  github.com/tendermint/tendermint/rpc/client_test.TestTxEventsSentWithBroadcastTxSync.func1()
      /go/src/github.com/tendermint/tendermint/rpc/client/event_test.go:139 +0x298
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:827 +0x162

Goroutine 132 (running) created at:
  testing.(*T).Run()
      /usr/local/go/src/testing/testing.go:878 +0x659
  github.com/tendermint/tendermint/rpc/client_test.TestTxEventsSentWithBroadcastTxSync()
      /go/src/github.com/tendermint/tendermint/rpc/client/event_test.go:119 +0x186
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:827 +0x162
==================
```

lite client works (tested manually)

godoc comments

httpclient: do not close the out channel

use TimeoutBroadcastTxCommit

no timeout for unsubscribe

but 1s Local (5s HTTP) timeout for resubscribe

format code

change Subscribe#out cap to 1

and replace config vars with RPCConfig

TimeoutBroadcastTxCommit can't be greater than rpcserver.WriteTimeout

rpc: Context as first parameter to all functions

reformat code

fixes after my own review

fixes after Ethan's review

add test stubs

fix config.toml

* fixes after manual testing

- rpc: do not recommend to use BroadcastTxCommit because it's slow and wastes
Tendermint resources (pubsub)
- rpc: better error in Subscribe and BroadcastTxCommit
- HTTPClient: do not resubscribe if err = ErrAlreadySubscribed

* fixes after Ismail's review

* Update rpc/grpc/grpc_test.go

Co-Authored-By: melekes <anton.kalyaev@gmail.com>

* Vagrantfile: install dev_tools

Follow-up on https://github.com/tendermint/tendermint/pull/2824

* update consensus params spec

* fix test name

* rpc_test: panic if failed to start listener

also
- remove http_server#MustListen
- align StartHTTPServer and StartHTTPAndTLSServer functions

* dep: allow minor releases for grpc

* Decouple StartHTTP{,AndTLS}Server from Listen()

This should help solve cosmos/cosmos-sdk#2715

* Fix small mistake

* Update StartGRPCServer

* s/rpc/rpcserver/

* Start grpccore.StartGRPCServer in a goroutine

* Reinstate l.Close()

* Fix rpc/lib/test/main.go

* Update code comment

* update changelog and comments

* fix tm-monitor. more comments

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

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 #1740

also, expose limit option for number concurrent streams for gRPC
(unlimited by default)

This reverts commit 96a3502

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

otherwise, we're not testing ping/pongs.
see https://github.com/tendermint/tendermint/pull/687#issuecomment-332494735

server:
- always has read & write timeouts
- ping handler never blocks the reader (see A)
- sends regular pings to check up on a client

A:
at some point server write buffer can become full, so in order not to
block reads from a client (see
https://github.com/gorilla/websocket/issues/97), server may skip some
pongs. As a result, client may disconnect. But you either have to do
that or block the reader. There is no third way.

client:
- optional read & write timeouts
- optional ping/pong to measure latency