use RestPlainResponse to improve builder API rerror reporting (#5819)

beacon_chain/spec/mev/rest_capella_mev_calls.nim

@@ -22,13 +22,13 @@ proc registerValidator*(body: seq[SignedValidatorRegistrationV1]
 proc getHeaderCapella*(slot: Slot,
                        parent_hash: Eth2Digest,
                        pubkey: ValidatorPubKey
-                      ): RestResponse[GetHeaderResponseCapella] {.
+                      ): RestPlainResponse {.
      rest, endpoint: "/eth/v1/builder/header/{slot}/{parent_hash}/{pubkey}",
      meth: MethodGet, connection: {Dedicated, Close}.}
   ## https://github.com/ethereum/builder-specs/blob/v0.4.0/apis/builder/header.yaml
 
 proc submitBlindedBlock*(body: capella_mev.SignedBlindedBeaconBlock
-                        ): RestResponse[SubmitBlindedBlockResponseCapella] {.
+                        ): RestPlainResponse {.
      rest, endpoint: "/eth/v1/builder/blinded_blocks",
      meth: MethodPost, connection: {Dedicated, Close}.}
   ## https://github.com/ethereum/builder-specs/blob/v0.4.0/apis/builder/blinded_blocks.yaml

beacon_chain/spec/mev/rest_deneb_mev_calls.nim

@@ -15,13 +15,13 @@ export chronos, client, rest_types, eth2_rest_serialization
 proc getHeaderDeneb*(slot: Slot,
                      parent_hash: Eth2Digest,
                      pubkey: ValidatorPubKey
-                    ): RestResponse[GetHeaderResponseDeneb] {.
+                    ): RestPlainResponse {.
      rest, endpoint: "/eth/v1/builder/header/{slot}/{parent_hash}/{pubkey}",
      meth: MethodGet, connection: {Dedicated, Close}.}
   ## https://github.com/ethereum/builder-specs/blob/v0.4.0/apis/builder/header.yaml
 
 proc submitBlindedBlock*(body: deneb_mev.SignedBlindedBeaconBlock
-                        ): RestResponse[SubmitBlindedBlockResponseDeneb] {.
+                        ): RestPlainResponse {.
      rest, endpoint: "/eth/v1/builder/blinded_blocks",
      meth: MethodPost, connection: {Dedicated, Close}.}
   ## https://github.com/ethereum/builder-specs/blob/v0.4.0/apis/builder/blinded_blocks.yaml

beacon_chain/validators/beacon_validators.nim

@@ -568,34 +568,55 @@ proc getBlindedExecutionPayload[
   # Not ideal to use `when` where instead of splitting into separate functions,
   # but Nim doesn't overload on generic EPH type parameter.
   when EPH is capella.ExecutionPayloadHeader:
-    let blindedHeader = awaitWithTimeout(
-      payloadBuilderClient.getHeaderCapella(slot, executionBlockRoot, pubkey),
-      BUILDER_PROPOSAL_DELAY_TOLERANCE):
-        return err "Timeout obtaining Capella blinded header from builder"
+    let
+      response = awaitWithTimeout(
+        payloadBuilderClient.getHeaderCapella(
+          slot, executionBlockRoot, pubkey),
+        BUILDER_PROPOSAL_DELAY_TOLERANCE):
+          return err "Timeout obtaining Capella blinded header from builder"
+
+      res = decodeBytes(
+        GetHeaderResponseCapella, response.data, response.contentType)
+
+      blindedHeader = res.valueOr:
+        return err(
+          "Unable to decode Capella blinded header: " & $res.error &
+            " with HTTP status " & $response.status & ", Content-Type " &
+            $response.contentType & " and content " & $response.data)
   elif EPH is deneb_mev.BlindedExecutionPayloadAndBlobsBundle:
-    let blindedHeader = awaitWithTimeout(
-      payloadBuilderClient.getHeaderDeneb(slot, executionBlockRoot, pubkey),
-      BUILDER_PROPOSAL_DELAY_TOLERANCE):
-        return err "Timeout obtaining Deneb blinded header and blob bundle from builder"
+    let
+      response = awaitWithTimeout(
+        payloadBuilderClient.getHeaderDeneb(
+          slot, executionBlockRoot, pubkey),
+        BUILDER_PROPOSAL_DELAY_TOLERANCE):
+          return err "Timeout obtaining Deneb blinded header from builder"
+
+      res = decodeBytes(
+        GetHeaderResponseDeneb, response.data, response.contentType)
+
+      blindedHeader = res.valueOr:
+        return err(
+          "Unable to decode Deneb blinded header: " & $res.error &
+            " with HTTP status " & $response.status & ", Content-Type " &
+            $response.contentType & " and content " & $response.data)
   else:
     static: doAssert false
 
   const httpOk = 200
-  if blindedHeader.status != httpOk:
+  if response.status != httpOk:
     return err "getBlindedExecutionPayload: non-200 HTTP response"
   else:
     if not verify_builder_signature(
-        node.dag.cfg.genesisFork, blindedHeader.data.data.message,
-        blindedHeader.data.data.message.pubkey,
-        blindedHeader.data.data.signature):
+        node.dag.cfg.genesisFork, blindedHeader.data.message,
+        blindedHeader.data.message.pubkey, blindedHeader.data.signature):
       return err "getBlindedExecutionPayload: signature verification failed"
 
     when EPH is capella.ExecutionPayloadHeader:
       return ok((
-        blindedBlckPart: blindedHeader.data.data.message.header,
-        blockValue: blindedHeader.data.data.message.value))
+        blindedBlckPart: blindedHeader.data.message.header,
+        blockValue: blindedHeader.data.message.value))
     elif EPH is deneb_mev.BlindedExecutionPayloadAndBlobsBundle:
-      template builderBid: untyped = blindedHeader.data.data.message
+      template builderBid: untyped = blindedHeader.data.message
       return ok((
         blindedBlckPart: EPH(
           execution_payload_header: builderBid.header,

beacon_chain/validators/message_router_mev.nim

@@ -55,34 +55,51 @@ proc unblindAndRouteBlockMEV*(
 
   # By time submitBlindedBlock is called, must already have done slashing
   # protection check
-  let bundle =
+  let response =
     try:
       awaitWithTimeout(
           payloadBuilderRestClient.submitBlindedBlock(blindedBlock),
           BUILDER_BLOCK_SUBMISSION_DELAY_TOLERANCE):
         return err("Submitting blinded block 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: " & exc.msg)
     except CatchableError as exc:
       return err("exception in submitBlindedBlock: " & exc.msg)
 
   const httpOk = 200
-  if bundle.status != httpOk:
+  if response.status != httpOk:
     # https://github.com/ethereum/builder-specs/blob/v0.4.0/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.
     return err("submitBlindedBlock failed with HTTP error code " &
-      $bundle.status & ": " & $shortLog(blindedBlock))
+      $response.status & ": " & $shortLog(blindedBlock))
 
   when consensusFork >= ConsensusFork.Deneb:
-    template execution_payload: untyped = bundle.data.data.execution_payload
+    let
+      res = decodeBytes(
+        SubmitBlindedBlockResponseDeneb, response.data, response.contentType)
+
+      bundle = res.valueOr:
+        return err("Could not decode Deneb blinded block: " & $res.error &
+          " with HTTP status " & $response.status & ", Content-Type " &
+          $response.contentType & " and content " & $response.data)
+
+    template execution_payload: untyped = bundle.data.execution_payload
   else:
-    template execution_payload: untyped = bundle.data.data
+    let
+      res = decodeBytes(
+        SubmitBlindedBlockResponseCapella, response.data, response.contentType)
+
+      bundle = res.valueOr:
+        return err("Could not decode Capella blinded block: " & $res.error &
+          " with HTTP status " & $response.status & ", Content-Type " &
+          $response.contentType & " and content " & $response.data)
+
+    template execution_payload: untyped = bundle.data
+
   if hash_tree_root(blindedBlock.message.body.execution_payload_header) !=
       hash_tree_root(execution_payload):
     return err("unblinded payload doesn't match blinded payload header: " &
@@ -105,9 +122,9 @@ proc unblindAndRouteBlockMEV*(
 
   let blobsOpt =
     when consensusFork >= ConsensusFork.Deneb:
-      template blobs_bundle: untyped = bundle.data.data.blobs_bundle
+      template blobs_bundle: untyped = bundle.data.blobs_bundle
       if blindedBlock.message.body.blob_kzg_commitments !=
-          bundle.data.data.blobs_bundle.commitments:
+          bundle.data.blobs_bundle.commitments:
         return err("unblinded blobs bundle has unexpected commitments")
       let ok = verifyProofs(
           asSeq blobs_bundle.blobs,