implement deneb block and blob unblinding (#5496)

beacon_chain/validators/message_router_mev.nim

@@ -9,11 +9,13 @@
 
 import std/macros
 import metrics
+import stew/assign2
 import ../beacon_node
 
 from eth/async_utils import awaitWithTimeout
 from ../spec/datatypes/bellatrix import SignedBeaconBlock
 from ../spec/mev/rest_capella_mev_calls import submitBlindedBlock
+from ../spec/mev/rest_deneb_mev_calls import submitBlindedBlock
 
 const
   BUILDER_BLOCK_SUBMISSION_DELAY_TOLERANCE = 5.seconds
@@ -124,4 +126,79 @@ proc unblindAndRouteBlockMEV*(
     node: BeaconNode, payloadBuilderRestClient: RestClientRef,
     blindedBlockContents: deneb_mev.SignedBlindedBeaconBlockContents):
     Future[Result[Opt[BlockRef], string]] {.async.} =
-  debugRaiseAssert $denebImplementationMissing & ": makeBlindedBeaconBlockForHeadAndSlot"
+  template blindedBlock: untyped = blindedBlockContents.signed_blinded_block
+
+  info "Proposing blinded Builder API block and blobs",
+    blindedBlock = shortLog(blindedBlock)
+
+  # By time submitBlindedBlock is called, must already have done slashing
+  # protection check
+  let unblindedPayload =
+    try:
+      awaitWithTimeout(
+          payloadBuilderRestClient.submitBlindedBlock(blindedBlockContents),
+          BUILDER_BLOCK_SUBMISSION_DELAY_TOLERANCE):
+        return err("Submitting blinded block and blobs timed out")
+      # From here on, including error paths, disallow local EL production by
+      # returning Opt.some, regardless of whether on head or newBlock.
+    except RestDecodingError as exc:
+      return err("REST decoding error submitting blinded block and blobs: " & exc.msg)
+    except CatchableError as exc:
+      return err("exception in submitBlindedBlock: " & exc.msg)
+
+  const httpOk = 200
+  if unblindedPayload.status == httpOk:
+    if  hash_tree_root(
+          blindedBlock.message.body.execution_payload_header) !=
+        hash_tree_root(unblindedPayload.data.data.execution_payload):
+      debug "unblindAndRouteBlockMEV: unblinded payload doesn't match blinded payload",
+        blindedPayload =
+          blindedBlock.message.body.execution_payload_header
+    else:
+      # Signature provided is consistent with unblinded execution payload,
+      # so construct full beacon block
+      # https://github.com/ethereum/builder-specs/blob/v0.3.0/specs/bellatrix/validator.md#block-proposal
+      var signedBlock = deneb.SignedBeaconBlock(
+        signature: blindedBlock.signature)
+      copyFields(
+        signedBlock.message, blindedBlock.message,
+        getFieldNames(typeof(signedBlock.message)))
+      copyFields(
+        signedBlock.message.body, blindedBlock.message.body,
+        getFieldNames(typeof(signedBlock.message.body)))
+      assign(
+        signedBlock.message.body.execution_payload,
+        unblindedPayload.data.data.execution_payload)
+
+      signedBlock.root = hash_tree_root(signedBlock.message)
+
+      doAssert signedBlock.root == hash_tree_root(blindedBlock.message)
+
+      debug "unblindAndRouteBlockMEV: proposing unblinded block and blobs",
+        blck = shortLog(signedBlock)
+
+      let newBlockRef =
+        (await node.router.routeSignedBeaconBlock(
+          signedBlock, Opt.none(SignedBlobSidecars))).valueOr:
+          # submitBlindedBlock has run, so don't allow fallback to run
+          return err("routeSignedBeaconBlock error") # Errors logged in router
+
+      if newBlockRef.isSome:
+        beacon_block_builder_proposed.inc()
+        notice "Block proposed (MEV)",
+          blockRoot = shortLog(signedBlock.root), blck = shortLog(signedBlock),
+          signature = shortLog(signedBlock.signature)
+
+      discard $denebImplementationMissing & ": route unblinded blobs"
+
+      return ok newBlockRef
+  else:
+    debug "unblindAndRouteBlockMEV: submitBlindedBlock failed",
+      blindedBlock, payloadStatus = unblindedPayload.status
+
+  # https://github.com/ethereum/builder-specs/blob/v0.3.0/specs/bellatrix/validator.md#proposer-slashing
+  # This means if a validator publishes a signature for a
+  # `BlindedBeaconBlock` (via a dissemination of a
+  # `SignedBlindedBeaconBlock`) then the validator **MUST** not use the
+  # local build process as a fallback, even in the event of some failure
+  # with the external builder network.