fix: add accept: application/json header to remote signer requests and improve invalid response handling

packages/cli/src/cmds/validator/signers/index.ts

@@ -16,6 +16,8 @@ import {importKeystoreDefinitionsFromExternalDir, readPassphraseOrPrompt} from "
 
 const KEYSTORE_IMPORT_PROGRESS_MS = 10000;
 
+type MinimalLogger = Pick<Logger, LogLevel.info | LogLevel.warn | LogLevel.debug>;
+
 /**
  * Options processing hierarchy
  * --interopIndexes
@@ -44,7 +46,7 @@ const KEYSTORE_IMPORT_PROGRESS_MS = 10000;
 export async function getSignersFromArgs(
   args: IValidatorCliArgs & GlobalArgs,
   network: string,
-  {logger, signal}: {logger: Pick<Logger, LogLevel.info | LogLevel.warn | LogLevel.debug>; signal: AbortSignal}
+  {logger, signal}: {logger: MinimalLogger; signal: AbortSignal}
 ): Promise<Signer[]> {
   const accountPaths = getAccountPaths(args, network);
 
@@ -106,7 +108,7 @@ export async function getSignersFromArgs(
 
   // Remote keys are declared manually or will be fetched from external signer
   else if (args["externalSigner.pubkeys"] || args["externalSigner.fetch"]) {
-    return getRemoteSigners(args);
+    return getRemoteSigners(args, logger);
   }
 
   // Read keys from local account manager
@@ -155,7 +157,7 @@ export function getSignerPubkeyHex(signer: Signer): string {
   }
 }
 
-async function getRemoteSigners(args: IValidatorCliArgs & GlobalArgs): Promise<Signer[]> {
+async function getRemoteSigners(args: IValidatorCliArgs & GlobalArgs, logger?: MinimalLogger): Promise<Signer[]> {
   const externalSignerUrl = args["externalSigner.url"];
   if (!externalSignerUrl) {
     throw new YargsError(
@@ -171,7 +173,7 @@ async function getRemoteSigners(args: IValidatorCliArgs & GlobalArgs): Promise<S
     throw new YargsError("externalSigner.pubkeys is set to an empty list");
   }
 
-  const pubkeys = args["externalSigner.pubkeys"] ?? (await externalSignerGetKeys(externalSignerUrl));
+  const pubkeys = args["externalSigner.pubkeys"] ?? (await externalSignerGetKeys(externalSignerUrl, logger));
   assertValidPubkeysHex(pubkeys);
 
   return pubkeys.map((pubkey) => ({type: SignerType.Remote, pubkey, url: externalSignerUrl}));

packages/validator/src/util/externalSignerClient.ts

@@ -7,6 +7,7 @@ import {BeaconConfig} from "@lodestar/config";
 import {computeEpochAtSlot, blindedOrFullBlockToHeader} from "@lodestar/state-transition";
 import {allForks, Epoch, Root, RootHex, Slot, ssz} from "@lodestar/types";
 import {PubkeyHex} from "../types.js";
+import {Logger, LogLevel} from "@lodestar/utils";
 
 /* eslint-disable @typescript-eslint/naming-convention */
 
@@ -25,6 +26,8 @@ export enum SignableMessageType {
   BLS_TO_EXECUTION_CHANGE = "BLS_TO_EXECUTION_CHANGE",
 }
 
+type MinimalLogger = Pick<Logger, LogLevel.info | LogLevel.warn | LogLevel.debug>;
+
 const AggregationSlotType = new ContainerType({
   slot: ssz.Slot,
 });
@@ -104,13 +107,28 @@ type Web3SignerSerializedRequest = {
 /**
  * Return public keys from the server.
  */
-export async function externalSignerGetKeys(externalSignerUrl: string): Promise<string[]> {
+export async function externalSignerGetKeys(externalSignerUrl: string, logger?: MinimalLogger): Promise<string[]> {
   const res = await fetch(`${externalSignerUrl}/api/v1/eth2/publicKeys`, {
     method: "GET",
     headers: {"Content-Type": "application/json"},
   });
 
-  return handlerExternalSignerResponse<string[]>(res);
+  if (!res.ok) {
+    const errBody = await res.text();
+    throw Error(`External signer GetKeys: statusCode=${res.status}, errorBody=${errBody}`);
+  }
+
+  const resBody = await res.text();
+  const resContentType = res.headers?.get("Content-Type")?.split(";", 1)[0].trim().toLowerCase();
+
+  logger?.debug("External signer GetKeys response", {contentType: resContentType, body: resBody});
+
+  if(resContentType === "application/json") {
+    return JSON.parse(resBody) as string[];
+  }
+  else {
+    throw Error(`External signer GetKeys: content type ${resContentType} not supported`);
+  }
 }
 
 /**
@@ -122,7 +140,8 @@ export async function externalSignerPostSignature(
   pubkeyHex: PubkeyHex,
   signingRoot: Root,
   signingSlot: Slot,
-  signableMessage: SignableMessage
+  signableMessage: SignableMessage,
+  logger?: MinimalLogger
 ): Promise<string> {
   const requestObj = serializerSignableMessagePayload(config, signableMessage) as Web3SignerSerializedRequest;
 
@@ -147,30 +166,57 @@ export async function externalSignerPostSignature(
     body: JSON.stringify(requestObj),
   });
 
-  const data = await handlerExternalSignerResponse<{signature: string}>(res);
-  return data.signature;
+  if (!res.ok) {
+    const errBody = await res.text();
+    throw Error(`External signer PostSignature: statusCode=${res.status}, errorBody=${errBody}`);
+  }
+
+  const resBody = await res.text();
+  const resContentType = res.headers?.get("Content-Type")?.split(";", 1)[0].trim().toLowerCase();
+
+  logger?.debug("External signer PostSignature response", {contentType: resContentType, body: resBody});
+
+  if(resContentType === "application/json") {
+    const data = JSON.parse(resBody) as {signature: string};
+    return data.signature;
+  }
+  else if (resContentType === "text/plain") {
+    return resBody;
+  }
+  else {
+    throw Error(`External signer PostSignature: content type ${resContentType} not supported`);
+  }
 }
 
 /**
  * Return upcheck status from server.
  */
-export async function externalSignerUpCheck(remoteUrl: string): Promise<boolean> {
+export async function externalSignerUpCheck(remoteUrl: string, logger?: MinimalLogger): Promise<boolean> {
   const res = await fetch(`${remoteUrl}/upcheck`, {
     method: "GET",
     headers: {"Content-Type": "application/json"},
   });
 
-  const data = await handlerExternalSignerResponse<{status: string}>(res);
-  return data.status === "OK";
-}
-
-async function handlerExternalSignerResponse<T>(res: Response): Promise<T> {
   if (!res.ok) {
     const errBody = await res.text();
-    throw Error(`${errBody}`);
+    throw Error(`External signer UpCheck: statusCode=${res.status}, errorBody=${errBody}`);
   }
 
-  return JSON.parse(await res.text()) as T;
+  const resBody = await res.text();
+  const resContentType = res.headers?.get("Content-Type")?.split(";", 1)[0].trim().toLowerCase();
+
+  logger?.debug("External signer UpCheck response", {contentType: resContentType, body: resBody});
+
+  if(resContentType === "application/json") {
+    const data = JSON.parse(resBody) as {status: string};
+    return data.status === "OK";
+  }
+  else if (resContentType === "text/plain") {
+    return resBody === "OK";
+  }
+  else{
+    throw Error(`External signer UpCheck: content type ${resContentType} not supported`);
+  }
 }
 
 function serializerSignableMessagePayload(config: BeaconConfig, payload: SignableMessage): Record<string, unknown> {