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

instead of panicking
Closes #5529

...rrayHTTP 

Closes #5135

Also, wrote a test for WriteRPCResponseHTTPError and used it with correct status codes according to https://www.jsonrpc.org/historical/json-rpc-over-http.html#response-codes

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

Closes #4603

Commands used (VIM):

```
:args `rg -l errors.Wrap`
:argdo normal @q | update
```

where q is a macros rewriting the `errors.Wrap` to `fmt.Errorf`.

Fixes #4802. The Go HTTP server has a global panic handler for requests, so it was not as severe as first thought.

This fix can still panic, since we try to send a `500` response - if that happens, the Go HTTP server will terminate the connection. Otherwise, the client will get a 200 response, which we should avoid. I'm sort of torn on whether it's even necessary to include this fix, instead of just letting the HTTP server deal with it.

https://www.jsonrpc.org/specification

What is done in this PR:

    JSONRPCClient: validate that Response.ID matches Request.ID I wanted
    to do the same for the WSClient, but since we're sending events as
    responses, not notifications, checking IDs would require storing
    them in memory indefinitely (and we won't be able to remove them
    upon client unsubscribing because ID is different then).

    Request.ID is now optional. Notification is a Request without an ID.
    Previously "" or 0 were considered as notifications

    Remove #event suffix from ID from an event response (partially fixes
    #2949) ID must be either string, int or null AND must be equal to
    request's ID. Now, because we've implemented events as responses, WS
    clients are tripping when they see Response.ID("0#event") !=
    Request.ID("0"). Implementing events as requests would require a lot
    of time (~ 2 days to completely rewrite WS client and server)

    generate unique ID for each request

    switch to integer IDs instead of "json-client-XYZ"
    id=0 method=/subscribe
    id=0 result=...
    id=1 method=/abci_query
    id=1 result=...

> send events (resulting from /subscribe) as requests+notifications (not
responses)

this will require a lot of work. probably not worth it

* rpc: generate an unique ID for each request
in conformance with JSON-RPC spec

* WSClient: check for unsolicited responses

* fix golangci warnings

* save commit

* fix errors

* remove ID from responses from subscribe
Refs #2949

* clients are safe for concurrent access

* tm-bench: switch to int ID

* fixes after my own review

* comment out sentIDs in WSClient
see commit body for the reason

* remove body.Close
it will be closed automatically

* stop ws connection outside of write/read routines
also, use t.Rate in tm-bench indexer when calculating ID

fix gocritic issues

* update swagger.yaml

* Apply suggestions from code review

* fix stylecheck and golint linter warnings

* update changelog

* update changelog2

* Fix long line errors in abci, crypto, and libs packages

* Fix long lines in p2p and rpc packages

* Fix long lines in abci, state, and tools packages

* Fix long lines in behaviour and blockchain packages

* Fix long lines in cmd and config packages

* Begin fixing long lines in consensus package

* Finish fixing long lines in consensus package

* Add lll exclusion for lines containing URLs

* Fix long lines in crypto package

* Fix long lines in evidence package

* Fix long lines in mempool and node packages

* Fix long lines in libs package

* Fix long lines in lite package

* Fix new long line in node package

* Fix long lines in p2p package

* Ignore gocritic warning

* Fix long lines in privval package

* Fix long lines in rpc package

* Fix long lines in scripts package

* Fix long lines in state package

* Fix long lines in tools package

* Fix long lines in types package

* Enable lll linter

* rpc: make max_body_bytes and max_header_bytes configurable

* update changelog pending

Continues from #3280 in building support for batched requests/responses in the JSON RPC (as per issue #3213).

* Add JSON RPC batching for client and server

As per #3213, this adds support for [JSON RPC batch requests and
responses](https://www.jsonrpc.org/specification#batch).

* Add additional checks to ensure client responses are the same as results

* Fix case where a notification is sent and no response is expected

* Add test to check that JSON RPC notifications in a batch are left out in responses

* Update CHANGELOG_PENDING.md

* Update PR number now that PR has been created

* Make errors start with lowercase letter

* Refactor batch functionality to be standalone

This refactors the batching functionality to rather act in a standalone
way. In light of supporting concurrent goroutines making use of the same
client, it would make sense to have batching functionality where one
could create a batch of requests per goroutine and send that batch
without interfering with a batch from another goroutine.

* Add examples for simple and batch HTTP client usage

* Check errors from writer and remove nolinter directives

* Make error strings start with lowercase letter

* Refactor examples to make them testable

* Use safer deferred shutdown for example Tendermint test node

* Recompose rpcClient interface from pre-existing interface components

* Rename WaitGroup for brevity

* Replace empty ID string with request ID

* Remove extraneous test case

* Convert first letter of errors.Wrap() messages to lowercase

* Remove extraneous function parameter

* Make variable declaration terse

* Reorder WaitGroup.Done call to help prevent race conditions in the face of failure

* Swap mutex to value representation and remove initialization

* Restore empty JSONRPC string ID in response to prevent nil

* Make JSONRPCBufferedRequest private

* Revert PR hard link in CHANGELOG_PENDING

* Add client ID for JSONRPCClient

This adds code to automatically generate a randomized client ID for the
JSONRPCClient, and adds a check of the IDs in the responses (if one was
set in the requests).

* Extract response ID validation into separate function

* Remove extraneous comments

* Reorder fields to indicate clearly which are protected by the mutex

* Refactor for loop to remove indexing

* Restructure and combine loop

* Flatten conditional block for better readability

* Make multi-variable declaration slightly more readable

* Change for loop style

* Compress error check statements

* Make function description more generic to show that we support different protocols

* Preallocate memory for request and result objects

* 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

* Fixed accepting integer IDs in requests for Tendermint RPC server (#2366)

* added a wrapper interface `jsonrpcid` that represents both string and int IDs in JSON-RPC requests/responses + custom JSON unmarshallers

* changed client-side code in RPC that uses it

* added extra tests for integer IDs

* updated CHANGELOG_PENDING, as suggested by PR instructions

* addressed PR comments

* added table driven tests for request type marshalling/unmarshalling
* expanded handler test to check IDs
* changed pending changelog note

* changed json rpc request/response unmarshalling to use empty interfaces and type switches on ID

* some cleanup

* Replaces our current http servers where connections stay open forever with ones with timeouts to prevent file descriptor exhaustion

* Use the correct handler

* Put in go routines

* fix err

* changelog

* rpc: export Read/WriteTimeout

The `broadcast_tx_commit` endpoint has it's own timeout.
If this is longer than the http server's WriteTimeout, the
user will receive an error. Here, we export the WriteTimeout
and set the broadcast_tx_commit timeout to be less than it.

In the future, we should use a config struct for the timeouts
to avoid the need to export. The broadcast_tx_commit timeout
may also become configurable, but we must check that it's less
than the server's WriteTimeout.

* 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

Closes: #2460

* Pass http.ServeTLS() errors back to the caller
* Update CHANGELOG
* Amend StartHTTPServer() too for consistency's sake
* Revert "Amend StartHTTPServer() too for consistency's sake"
This reverts commit 23bfb4c2e9.

* 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.

Also, fix consensus liveness issue.

Refs #1740

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

This reverts commit 96a3502

```
data
A Primitive or Structured value that contains additional information about the error.
This may be omitted.
The value of this member is defined by the Server (e.g. detailed error information, nested errors etc.).
```