VC: Runtime config (#5130)

* Make VC able to understand any type of `/eth/v1/config/spec` response without any changes in source code.
Update compatibility checking.
Now VC is able to obtain any constant from `spec` call.

* Remove RestSpecVC declaration.

beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim

@@ -2996,6 +2996,16 @@ proc readValue*(reader: var JsonReader[RestJson],
     stacktraces: stacktraces
   )
 
+## VCRuntimeConfig
+proc readValue*(reader: var JsonReader[RestJson],
+                value: var VCRuntimeConfig) {.
+     raises: [SerializationError, IOError, Defect].} =
+  for fieldName in readObjectFields(reader):
+    let fieldValue = reader.readValue(string)
+    if value.hasKeyOrPut(toUpperAscii(fieldName), fieldValue):
+      let msg = "Multiple `" & fieldName & "` fields found"
+      reader.raiseUnexpectedField(msg, "VCRuntimeConfig")
+
 proc parseRoot(value: string): Result[Eth2Digest, cstring] =
   try:
     ok(Eth2Digest(data: hexToByteArray[32](value)))

beacon_chain/spec/eth2_apis/rest_types.nim

@@ -14,7 +14,7 @@
 {.push raises: [].}
 
 import
-  std/json,
+  std/[json, tables],
   stew/base10, web3/ethtypes,
   ".."/forks,
   ".."/datatypes/[phase0, altair, bellatrix, deneb],
@@ -22,7 +22,8 @@ import
 
 from ".."/datatypes/capella import BeaconBlockBody
 
-export forks, phase0, altair, bellatrix, capella, bellatrix_mev, capella_mev
+export forks, phase0, altair, bellatrix, capella, bellatrix_mev, capella_mev,
+       tables
 
 const
   # https://github.com/ethereum/eth2.0-APIs/blob/master/apis/beacon/states/validator_balances.yaml#L17
@@ -478,38 +479,7 @@ type
     TARGET_AGGREGATORS_PER_SYNC_SUBCOMMITTEE*: uint64
     SYNC_COMMITTEE_SUBNET_COUNT*: uint64
 
-  # The `RestSpec` is a dynamic dictionary that includes version-specific spec
+  VCRuntimeConfig* = Table[string, string]
-  # constants. New versions may introduce new constants, and remove old ones.
-  # The Nimbus validator client fetches the remote spec to determine whether it
-  # is connected to a compatible beacon node. For this purpose, it only needs to
-  # verify a small set of relevant spec constants. To avoid rejecting a remote
-  # spec that includes all of those relevant spec constants, but that does not
-  # include all of the locally known spec constants, a separate type is defined
-  # that includes just the spec constants relevant for the validator client.
-  # Extra spec constants are silently ignored.
-  RestSpecVC* = object
-    # /!\ Keep in sync with `validator_client/api.nim` > `checkCompatible`.
-    MAX_VALIDATORS_PER_COMMITTEE*: uint64
-    SLOTS_PER_EPOCH*: uint64
-    SECONDS_PER_SLOT*: uint64
-    EPOCHS_PER_ETH1_VOTING_PERIOD*: uint64
-    SLOTS_PER_HISTORICAL_ROOT*: uint64
-    EPOCHS_PER_HISTORICAL_VECTOR*: uint64
-    EPOCHS_PER_SLASHINGS_VECTOR*: uint64
-    HISTORICAL_ROOTS_LIMIT*: uint64
-    VALIDATOR_REGISTRY_LIMIT*: uint64
-    MAX_PROPOSER_SLASHINGS*: uint64
-    MAX_ATTESTER_SLASHINGS*: uint64
-    MAX_ATTESTATIONS*: uint64
-    MAX_DEPOSITS*: uint64
-    MAX_VOLUNTARY_EXITS*: uint64
-    DOMAIN_BEACON_PROPOSER*: DomainType
-    DOMAIN_BEACON_ATTESTER*: DomainType
-    DOMAIN_RANDAO*: DomainType
-    DOMAIN_DEPOSIT*: DomainType
-    DOMAIN_VOLUNTARY_EXIT*: DomainType
-    DOMAIN_SELECTION_PROOF*: DomainType
-    DOMAIN_AGGREGATE_AND_PROOF*: DomainType
 
   RestDepositContract* = object
     chain_id*: string
@@ -692,7 +662,7 @@ type
   GetPoolVoluntaryExitsResponse* = DataEnclosedObject[seq[SignedVoluntaryExit]]
   GetProposerDutiesResponse* = DataRootEnclosedObject[seq[RestProposerDuty]]
   GetSpecResponse* = DataEnclosedObject[RestSpec]
-  GetSpecVCResponse* = DataEnclosedObject[RestSpecVC]
+  GetSpecVCResponse* = DataEnclosedObject[VCRuntimeConfig]
   GetStateFinalityCheckpointsResponse* = DataEnclosedObject[RestBeaconStatesFinalityCheckpoints]
   GetStateForkResponse* = DataEnclosedObject[Fork]
   GetStateRootResponse* = DataOptimisticObject[RestRoot]

beacon_chain/validator_client/common.nim

@@ -119,7 +119,7 @@ type
   BeaconNodeServer* = object
     client*: RestClientRef
     endpoint*: string
-    config*: Opt[RestSpecVC]
+    config*: VCRuntimeConfig
     ident*: Opt[string]
     genesis*: Opt[RestGenesis]
     syncInfo*: Opt[RestSyncInfo]
@@ -451,29 +451,62 @@ chronicles.expandIt(SyncCommitteeDuty):
   validator_index = it.validator_index
   validator_sync_committee_index = it.validator_sync_committee_index
 
-proc checkConfig*(info: RestSpecVC): bool =
+proc equals*(info: VCRuntimeConfig, name: string, check: uint64): bool =
-  # /!\ Keep in sync with `spec/eth2_apis/rest_types.nim` > `RestSpecVC`.
+  let numstr = info.getOrDefault(name, "missing")
-  info.MAX_VALIDATORS_PER_COMMITTEE == MAX_VALIDATORS_PER_COMMITTEE and
+  if numstr == "missing": return false
-  info.SLOTS_PER_EPOCH == SLOTS_PER_EPOCH and
+  let value = Base10.decode(uint64, numstr).valueOr:
-  info.SECONDS_PER_SLOT == SECONDS_PER_SLOT and
+    return false
-  info.EPOCHS_PER_ETH1_VOTING_PERIOD == EPOCHS_PER_ETH1_VOTING_PERIOD and
+  value == check
-  info.SLOTS_PER_HISTORICAL_ROOT == SLOTS_PER_HISTORICAL_ROOT and
+
-  info.EPOCHS_PER_HISTORICAL_VECTOR == EPOCHS_PER_HISTORICAL_VECTOR and
+proc equals*(info: VCRuntimeConfig, name: string, check: DomainType): bool =
-  info.EPOCHS_PER_SLASHINGS_VECTOR == EPOCHS_PER_SLASHINGS_VECTOR and
+  let domstr = info.getOrDefault(name, "missing")
-  info.HISTORICAL_ROOTS_LIMIT == HISTORICAL_ROOTS_LIMIT and
+  if domstr == "missing": return false
-  info.VALIDATOR_REGISTRY_LIMIT == VALIDATOR_REGISTRY_LIMIT and
+  let value =
-  info.MAX_PROPOSER_SLASHINGS == MAX_PROPOSER_SLASHINGS and
+    try:
-  info.MAX_ATTESTER_SLASHINGS == MAX_ATTESTER_SLASHINGS and
+      var dres: DomainType
-  info.MAX_ATTESTATIONS == MAX_ATTESTATIONS and
+      hexToByteArray(domstr, distinctBase(dres))
-  info.MAX_DEPOSITS == MAX_DEPOSITS and
+      dres
-  info.MAX_VOLUNTARY_EXITS == MAX_VOLUNTARY_EXITS and
+    except ValueError:
-  info.DOMAIN_BEACON_PROPOSER == DOMAIN_BEACON_PROPOSER and
+      return false
-  info.DOMAIN_BEACON_ATTESTER == DOMAIN_BEACON_ATTESTER and
+  value == check
-  info.DOMAIN_RANDAO == DOMAIN_RANDAO and
+
-  info.DOMAIN_DEPOSIT == DOMAIN_DEPOSIT and
+proc equals*(info: VCRuntimeConfig, name: string, check: Epoch): bool =
-  info.DOMAIN_VOLUNTARY_EXIT == DOMAIN_VOLUNTARY_EXIT and
+  info.equals(name, uint64(check))
-  info.DOMAIN_SELECTION_PROOF == DOMAIN_SELECTION_PROOF and
+
-  info.DOMAIN_AGGREGATE_AND_PROOF == DOMAIN_AGGREGATE_AND_PROOF
+proc getOrDefault*(info: VCRuntimeConfig, name: string,
+                   default: uint64): uint64 =
+  let numstr = info.getOrDefault(name, "missing")
+  if numstr == "missing": return default
+  Base10.decode(uint64, numstr).valueOr:
+    return default
+
+proc getOrDefault*(info: VCRuntimeConfig, name: string, default: Epoch): Epoch =
+  Epoch(info.getOrDefault(name, uint64(default)))
+
+proc checkConfig*(c: VCRuntimeConfig): bool =
+  c.equals("MAX_VALIDATORS_PER_COMMITTEE", MAX_VALIDATORS_PER_COMMITTEE) and
+  c.equals("SLOTS_PER_EPOCH", SLOTS_PER_EPOCH) and
+  c.equals("SECONDS_PER_SLOT", SECONDS_PER_SLOT) and
+  c.equals("EPOCHS_PER_ETH1_VOTING_PERIOD", EPOCHS_PER_ETH1_VOTING_PERIOD) and
+  c.equals("SLOTS_PER_HISTORICAL_ROOT", SLOTS_PER_HISTORICAL_ROOT) and
+  c.equals("EPOCHS_PER_HISTORICAL_VECTOR", EPOCHS_PER_HISTORICAL_VECTOR) and
+  c.equals("EPOCHS_PER_SLASHINGS_VECTOR", EPOCHS_PER_SLASHINGS_VECTOR) and
+  c.equals("HISTORICAL_ROOTS_LIMIT", HISTORICAL_ROOTS_LIMIT) and
+  c.equals("VALIDATOR_REGISTRY_LIMIT", VALIDATOR_REGISTRY_LIMIT) and
+  c.equals("MAX_PROPOSER_SLASHINGS", MAX_PROPOSER_SLASHINGS) and
+  c.equals("MAX_ATTESTER_SLASHINGS", MAX_ATTESTER_SLASHINGS) and
+  c.equals("MAX_ATTESTATIONS", MAX_ATTESTATIONS) and
+  c.equals("MAX_DEPOSITS", MAX_DEPOSITS) and
+  c.equals("MAX_VOLUNTARY_EXITS", MAX_VOLUNTARY_EXITS) and
+  c.equals("DOMAIN_BEACON_PROPOSER", DOMAIN_BEACON_PROPOSER) and
+  c.equals("DOMAIN_BEACON_ATTESTER", DOMAIN_BEACON_ATTESTER) and
+  c.equals("DOMAIN_RANDAO", DOMAIN_RANDAO) and
+  c.equals("DOMAIN_DEPOSIT", DOMAIN_DEPOSIT) and
+  c.equals("DOMAIN_VOLUNTARY_EXIT", DOMAIN_VOLUNTARY_EXIT) and
+  c.equals("DOMAIN_SELECTION_PROOF", DOMAIN_SELECTION_PROOF) and
+  c.equals("DOMAIN_AGGREGATE_AND_PROOF", DOMAIN_AGGREGATE_AND_PROOF) and
+  c.hasKey("ALTAIR_FORK_VERSION") and c.hasKey("ALTAIR_FORK_EPOCH") and
+  not(c.equals("ALTAIR_FORK_EPOCH", FAR_FUTURE_EPOCH))
 
 proc updateStatus*(node: BeaconNodeServerRef,
                    status: RestBeaconNodeStatus,

beacon_chain/validator_client/fallback_service.nim

@@ -139,7 +139,7 @@ proc checkCompatible(
     genesisFlag = (genesis != vc.beaconGenesis)
     configFlag = not(checkConfig(info))
 
-  node.config = Opt.some(info)
+  node.config = info
   node.genesis = Opt.some(genesis)
   let res =
     if configFlag or genesisFlag: