VC+BN: Validator voluntary exits through the Keymanager API (#5020)

* Initial commit.

* Address review comments.

beacon_chain/nimbus_beacon_node.nim

@@ -666,6 +666,12 @@ proc init*(T: type BeaconNode,
     withState(dag.headState):
       getValidator(forkyState().data.validators.asSeq(), pubkey)
 
+  proc getForkForEpoch(epoch: Epoch): Opt[Fork] =
+    Opt.some(dag.forkAtEpoch(epoch))
+
+  proc getGenesisRoot(): Eth2Digest =
+    getStateField(dag.headState, genesis_validators_root)
+
   let
     slashingProtectionDB =
       SlashingProtectionDB.init(
@@ -685,7 +691,9 @@ proc init*(T: type BeaconNode,
         config.defaultFeeRecipient,
         config.suggestedGasLimit,
         getValidatorAndIdx,
-        getBeaconTime)
+        getBeaconTime,
+        getForkForEpoch,
+        getGenesisRoot)
     else: nil
 
     stateTtlCache =

beacon_chain/nimbus_validator_client.nim

@@ -310,6 +310,15 @@ proc asyncInit(vc: ValidatorClientRef): Future[ValidatorClientRef] {.async.} =
   let
     keymanagerInitResult = initKeymanagerServer(vc.config, nil)
 
+  proc getForkForEpoch(epoch: Epoch): Opt[Fork] =
+    if len(vc.forks) > 0:
+      Opt.some(vc.forkAtEpoch(epoch))
+    else:
+      Opt.none(Fork)
+
+  proc getGenesisRoot(): Eth2Digest =
+    vc.beaconGenesis.genesis_validators_root
+
   try:
     vc.fallbackService = await FallbackServiceRef.init(vc)
     vc.forkService = await ForkServiceRef.init(vc)
@@ -329,7 +338,10 @@ proc asyncInit(vc: ValidatorClientRef): Future[ValidatorClientRef] {.async.} =
         vc.config.defaultFeeRecipient,
         vc.config.suggestedGasLimit,
         nil,
-        vc.beaconClock.getBeaconTimeFn)
+        vc.beaconClock.getBeaconTimeFn,
+        getForkForEpoch,
+        getGenesisRoot
+        )
 
   except CatchableError as exc:
     warn "Unexpected error encountered while initializing",

beacon_chain/rpc/rest_constants.nim

@@ -115,6 +115,8 @@ const
     "Invalid subscription request object(s)"
   ValidatorNotFoundError* =
     "Could not find validator"
+  ValidatorIndexMissingError* =
+    "Validator missing index value"
   ValidatorStatusNotFoundError* =
     "Could not obtain validator's status"
   TooHighValidatorIndexValueError* =
@@ -234,3 +236,5 @@ const
     "The given merkle proof is invalid"
   InvalidMerkleProofIndexError* =
     "The given merkle proof index is invalid"
+  FailedToObtainForkError* =
+    "Failed to obtain fork information"

beacon_chain/rpc/rest_key_management_api.nim

@@ -23,8 +23,8 @@ func validateKeymanagerApiQueries*(key: string, value: string): int =
   # There are no queries to validate
   return 0
 
-proc listLocalValidators*(validatorPool: ValidatorPool): seq[KeystoreInfo]
-                         {.raises: [Defect].} =
+proc listLocalValidators*(validatorPool: ValidatorPool): seq[KeystoreInfo] {.
+     raises: [Defect].} =
   var validators: seq[KeystoreInfo]
   for item in validatorPool:
     if item.kind == ValidatorKind.Local:
@@ -35,8 +35,9 @@ proc listLocalValidators*(validatorPool: ValidatorPool): seq[KeystoreInfo]
       )
   validators
 
-proc listRemoteValidators*(validatorPool: ValidatorPool): seq[RemoteKeystoreInfo]
-                          {.raises: [Defect].} =
+proc listRemoteValidators*(
+       validatorPool: ValidatorPool): seq[RemoteKeystoreInfo] {.
+     raises: [Defect].} =
   var validators: seq[RemoteKeystoreInfo]
   for item in validatorPool:
     if item.kind == ValidatorKind.Remote and item.data.remotes.len == 1:
@@ -46,8 +47,9 @@ proc listRemoteValidators*(validatorPool: ValidatorPool): seq[RemoteKeystoreInfo
       )
   validators
 
-proc listRemoteDistributedValidators*(validatorPool: ValidatorPool): seq[DistributedKeystoreInfo]
-                                     {.raises: [Defect].} =
+proc listRemoteDistributedValidators*(
+       validatorPool: ValidatorPool): seq[DistributedKeystoreInfo] {.
+     raises: [Defect].} =
   var validators: seq[DistributedKeystoreInfo]
   for item in validatorPool:
     if item.kind == ValidatorKind.Remote and item.data.remotes.len > 1:
@@ -75,8 +77,9 @@ proc keymanagerApiError(status: HttpCode, msg: string): RestApiResponse =
         default
   RestApiResponse.error(status, data, "application/json")
 
-proc checkAuthorization*(request: HttpRequestRef,
-                         host: KeymanagerHost): Result[void, AuthorizationError] =
+proc checkAuthorization*(
+       request: HttpRequestRef,
+       host: KeymanagerHost): Result[void, AuthorizationError] =
   let authorizations = request.headers.getList("authorization")
   if authorizations.len > 0:
     for authHeader in authorizations:
@@ -522,3 +525,54 @@ proc installKeymanagerHandlers*(router: var RestRouter, host: KeymanagerHost) =
       response.data.add handleRemoveValidatorReq(host, key)
 
     return RestApiResponse.jsonResponsePlain(response)
+
+  # https://ethereum.github.io/keymanager-APIs/?urls.primaryName=dev#/Voluntary%20Exit/signVoluntaryExit
+  router.api(MethodPost, "/eth/v1/validator/{pubkey}/voluntary_exit") do (
+    pubkey: ValidatorPubKey, epoch: Option[Epoch],
+    contentBody: Option[ContentBody]) -> RestApiResponse:
+
+    let authStatus = checkAuthorization(request, host)
+    if authStatus.isErr():
+      return authErrorResponse(authStatus.error)
+
+    let
+      qpubkey = pubkey.valueOr:
+        return keymanagerApiError(Http400, InvalidValidatorPublicKey)
+      qepoch =
+        if epoch.isSome():
+          let res = epoch.get()
+          if res.isErr():
+            return keymanagerApiError(Http400, InvalidEpochValueError)
+          res.get()
+        else:
+          host.getBeaconTimeFn().slotOrZero().epoch()
+      validator =
+        block:
+          let res = host.validatorPool[].getValidator(qpubkey).valueOr:
+            return keymanagerApiError(Http404, ValidatorNotFoundError)
+          if res.index.isNone():
+            return keymanagerApiError(Http404, ValidatorIndexMissingError)
+          res
+      voluntaryExit =
+        VoluntaryExit(epoch: qepoch,
+                      validator_index: uint64(validator.index.get()))
+      fork = host.getForkFn(qepoch).valueOr:
+        return keymanagerApiError(Http500, FailedToObtainForkError)
+      signature =
+        try:
+          let res = await validator.getValidatorExitSignature(
+            fork, host.getGenesisFn(), voluntaryExit)
+          if res.isErr():
+            return keymanagerApiError(Http500, res.error())
+          res.get()
+        except CancelledError as exc:
+          raise exc
+        except CatchableError as exc:
+          error "An unexpected error occurred while signing validator exit",
+                err_name = exc.name, err_msg = exc.msg
+          return keymanagerApiError(Http500, $exc.msg)
+      response = SignedVoluntaryExit(
+        message: voluntaryExit,
+        signature: signature
+      )
+    return RestApiResponse.jsonResponse(response)

beacon_chain/validators/keystore_management.nim

@@ -69,6 +69,11 @@ type
     proc (pubkey: ValidatorPubKey): Opt[ValidatorAndIndex]
          {.raises: [Defect], gcsafe.}
 
+  GetForkFn* =
+    proc (epoch: Epoch): Opt[Fork] {.raises: [Defect], gcsafe.}
+  GetGenesisFn* =
+    proc (): Eth2Digest {.raises: [Defect], gcsafe.}
+
   KeymanagerHost* = object
     validatorPool*: ref ValidatorPool
     rng*: ref HmacDrbgContext
@@ -79,6 +84,8 @@ type
     defaultGasLimit*: uint64
     getValidatorAndIdxFn*: ValidatorPubKeyToDataFn
     getBeaconTimeFn*: GetBeaconTimeFn
+    getForkFn*: GetForkFn
+    getGenesisFn*: GetGenesisFn
 
   MultipleKeystoresDecryptor* = object
     previouslyUsedPassword*: string
@@ -104,7 +111,9 @@ func init*(T: type KeymanagerHost,
            defaultFeeRecipient: Opt[Eth1Address],
            defaultGasLimit: uint64,
            getValidatorAndIdxFn: ValidatorPubKeyToDataFn,
-           getBeaconTimeFn: GetBeaconTimeFn): T =
+           getBeaconTimeFn: GetBeaconTimeFn,
+           getForkFn: GetForkFn,
+           getGenesisFn: GetGenesisFn): T =
   T(validatorPool: validatorPool,
     rng: rng,
     keymanagerToken: keymanagerToken,
@@ -113,7 +122,9 @@ func init*(T: type KeymanagerHost,
     defaultFeeRecipient: defaultFeeRecipient,
     defaultGasLimit: defaultGasLimit,
     getValidatorAndIdxFn: getValidatorAndIdxFn,
-    getBeaconTimeFn: getBeaconTimeFn)
+    getBeaconTimeFn: getBeaconTimeFn,
+    getForkFn: getForkFn,
+    getGenesisFn: getGenesisFn)
 
 proc echoP*(msg: string) =
   ## Prints a paragraph aligned to 80 columns