*add validateChain higher order function for RPC validation

src/rpc/common.ts

@@ -8,6 +8,10 @@ import { ERR_INVALID_CHAIN } from "../error.js";
 
 type RpcProviderMethod = (method: string, params: Array<any>) => Promise<any>;
 
+interface RpcContext {
+  chain?: string;
+}
+
 const gatewayProviders: { [name: string]: RpcProviderMethod } = {};
 
 const gatewayMethods: {
@@ -126,3 +130,13 @@ class RpcError extends Error {
 export function rpcError(message: string): Promise<RpcError> {
   return Promise.reject(new RpcError(message));
 }
+
+export function validateChain(chain: string, handler: any) {
+  return async (args: any, context: RpcContext) => {
+    if (!context?.chain || "hns" !== context?.chain) {
+      return rpcError(ERR_INVALID_CHAIN);
+    }
+
+    return handler(args, context);
+  };
+}

src/rpc/dns.ts

@@ -2,7 +2,7 @@
 //const require = createRequire(import.meta.url);
 
 import { isIp } from "../util.js";
-import { RpcMethodList } from "./index.js";
+import { RpcMethodList, validateChain } from "./index.js";
 // @ts-ignore
 import bns from "bns";
 const { StubResolver, RecursiveResolver } = bns;
@@ -59,7 +59,7 @@ async function getDnsRecords(
 }
 
 export default {
-  dnslookup: async function (args: any) {
+  dnslookup: validateChain("icann", async function (args: any) {
     let dnsResults: string[] = [];
     let domain = args.domain;
     let ns = args.nameserver;
@@ -104,5 +104,5 @@ export default {
     }
 
     return false;
-  },
+  }),
 } as RpcMethodList;

src/rpc/handshake.ts

@@ -1,7 +1,7 @@
 //const require = createRequire(import.meta.url);
 //import { createRequire } from "module";
 
-import { rpcError, RpcMethodList } from "./index.js";
+import { rpcError, RpcMethodList, validateChain } from "./index.js";
 // @ts-ignore
 import rand from "random-key";
 // @ts-ignore
@@ -78,12 +78,7 @@ if (!config.bool("hsd-use-external-node")) {
 const hnsClient = new NodeClient(clientArgs);
 
 export default {
-  getnameresource: async (args: any, context: object) => {
-    // @ts-ignore
-    if ("hns" !== context.chain) {
-      throw rpcError(ERR_INVALID_CHAIN);
-    }
-
+  getnameresource: validateChain("hns", async (args: any) => {
     let resp;
     try {
       resp = await hnsClient.execute("getnameresource", args);
@@ -100,5 +95,5 @@ export default {
     }
 
     return resp;
-  },
+  }),
 } as RpcMethodList;

src/rpc/misc.ts

@@ -1,7 +1,7 @@
-import { RpcMethodList } from "./index";
+import { RpcMethodList, validateChain } from "./index.js";
 
 export default {
-  ping: async () => {
+  ping: validateChain("misc", async () => {
     return { pong: true };
-  },
+  }),
 } as RpcMethodList;