Increase REST server default limits. (#2991)

* Increase REST server default limits.

* Fix compilation error.

* Fix tests.

beacon_chain/nimbus_beacon_node.nim

@@ -65,9 +65,14 @@ template init(T: type RestServerRef, ip: ValidIpAddress, port: Port): T =
                      HttpServerFlags.NotifyDisconnect}
   # We increase default timeout to help validator clients who poll our server
   # at least once per slot (12.seconds).
-  let headersTimeout = seconds(2'i64 * int64(SECONDS_PER_SLOT))
+  let
+    headersTimeout = seconds(2'i64 * int64(SECONDS_PER_SLOT))
+    maxHeadersSize = 65536 # 64 kilobytes
+    maxRequestBodySize = 16_777_216 # 16 megabytes
   let res = RestServerRef.new(getRouter(), address, serverFlags = serverFlags,
-                              httpHeadersTimeout = headersTimeout)
+                              httpHeadersTimeout = headersTimeout,
+                              maxHeadersSize = maxHeadersSize,
+                              maxRequestBodySize = maxRequestBodySize)
   if res.isErr():
     notice "Rest server could not be started", address = $address,
            reason = res.error()

beacon_chain/spec/eth2_apis/rest_types.nim

@@ -24,7 +24,7 @@ export forks, phase0, altair
 const
   # https://github.com/ethereum/eth2.0-APIs/blob/master/apis/beacon/states/validator_balances.yaml#L17
   # https://github.com/ethereum/eth2.0-APIs/blob/master/apis/beacon/states/validators.yaml#L17
-  MaximumValidatorIds* = 30
+  MaximumValidatorIds* = 16384
 
 type
   EventTopic* {.pure.} = enum

ncli/resttest-rules.json

@@ -531,9 +531,9 @@
       "headers": {"Accept": "application/json"}
     },
     "response": {
-      "status": {"operator": "equals", "value": "400"},
+      "status": {"operator": "equals", "value": "200"},
       "headers": [{"key": "Content-Type", "value": "application/json", "operator": "equals"}],
-      "body": [{"operator": "jstructcmpns", "value": {"code": "", "message": ""}}]
+      "body": [{"operator": "jstructcmps", "start": ["data"], "value": [{"index": "", "balance": "", "status": "", "validator": {"pubkey": "", "withdrawal_credentials": "", "effective_balance": "", "slashed": false, "activation_eligibility_epoch": "", "activation_epoch": "", "exit_epoch": "", "withdrawable_epoch": ""}}]}]
     }
   },
   {
@@ -1218,9 +1218,9 @@
       "headers": {"Accept": "application/json"}
     },
     "response": {
-      "status": {"operator": "equals", "value": "400"},
+      "status": {"operator": "equals", "value": "200"},
       "headers": [{"key": "Content-Type", "value": "application/json", "operator": "equals"}],
-      "body": [{"operator": "jstructcmpns", "value": {"code": "", "message": ""}}]
+      "body": [{"operator": "jstructcmps", "start": ["data"], "value": [{"index": "", "balance": ""}]}]
     }
   },
   {