@metamask/snaps-rpc-methods/dist/permitted/middleware.mjs

MetaMask Snaps JSON-RPC method implementations

import { rpcErrors } from "@metamask/rpc-errors";
import { logError } from "@metamask/snaps-utils";
import { methodHandlers } from "./handlers.mjs";
import { selectHooks } from "../utils.mjs";
/**
 * Creates a middleware that handles permitted snap RPC methods.
 *
 * @param isSnap - A flag that should indicate whether the requesting origin is a snap or not.
 * @param hooks - An object containing the hooks made available to the permitted RPC methods.
 * @returns The middleware.
 */
export function createSnapsMethodMiddleware(isSnap, hooks) {
    // This is not actually a misused promise, the type is just wrong
    // eslint-disable-next-line @typescript-eslint/no-misused-promises
    return async function methodMiddleware(request, response, next, end) {
        const handler = methodHandlers[request.method];
        if (handler) {
            if (String.prototype.startsWith.call(request.method, 'snap_') &&
                !isSnap) {
                return end(rpcErrors.methodNotFound());
            }
            // TODO: Once json-rpc-engine types are up to date, we should type this correctly
            const { implementation, hookNames } = handler;
            try {
                // Implementations may or may not be async, so we must await them.
                return await implementation(request, response, next, end, selectHooks(hooks, hookNames));
            }
            catch (error) {
                logError(error);
                return end(error);
            }
        }
        return next();
    };
}
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