From 38605915c65e728bfb6c71c24b56d8804f297370 Mon Sep 17 00:00:00 2001
From: Jesse Chan <jc@linux.com>
Date: Wed, 3 Mar 2021 12:47:13 +0800
Subject: [PATCH] server: rTorrent: use JSON-RPC when available

---
 .../services/rTorrent/clientGatewayService.ts | 23 +++++--
 .../services/rTorrent/clientRequestManager.ts |  9 ++-
 server/services/rTorrent/util/scgiUtil.ts     | 67 ++++++++++++++++++-
 3 files changed, 90 insertions(+), 9 deletions(-)

diff --git a/server/services/rTorrent/clientGatewayService.ts b/server/services/rTorrent/clientGatewayService.ts
index 165a9baa..c6e1d4e3 100644
--- a/server/services/rTorrent/clientGatewayService.ts
+++ b/server/services/rTorrent/clientGatewayService.ts
@@ -804,14 +804,29 @@ class RTorrentClientGatewayService extends ClientGatewayService {
     torrentTracker: string[];
     transferSummary: string[];
   }> {
-    const methodList: Array<string> = await this.clientRequestManager
-      .methodCall('system.listMethods', [])
-      .then(this.processClientRequestSuccess, this.processRTorrentRequestError)
-      .catch((e) => {
+    let methodList: Array<string> = [];
+    const listMethods = () => {
+      return this.clientRequestManager
+        .methodCall('system.listMethods', [])
+        .then(this.processClientRequestSuccess, this.processRTorrentRequestError);
+    };
+
+    this.clientRequestManager.isJSONCapable = true;
+    methodList = await listMethods().catch((e: RPCError) => {
+      if (e.isRPCError || e.name == 'SyntaxError') {
+        this.clientRequestManager.isJSONCapable = false;
+      } else if (!fallback) {
+        throw e;
+      }
+    });
+
+    if (!this.clientRequestManager.isJSONCapable) {
+      methodList = await listMethods().catch((e) => {
         if (!fallback) {
           throw e;
         }
       });
+    }
 
     const getAvailableMethodCalls =
       methodList?.length > 0
diff --git a/server/services/rTorrent/clientRequestManager.ts b/server/services/rTorrent/clientRequestManager.ts
index c2ba1b6c..e934460c 100644
--- a/server/services/rTorrent/clientRequestManager.ts
+++ b/server/services/rTorrent/clientRequestManager.ts
@@ -2,8 +2,8 @@ import type {NetConnectOpts} from 'net';
 
 import type {RTorrentConnectionSettings} from '@shared/schema/ClientConnectionSettings';
 
+import {methodCallJSON, methodCallXML} from './util/scgiUtil';
 import {sanitizePath} from '../../util/fileUtil';
-import scgiUtil from './util/scgiUtil';
 
 import type {MultiMethodCalls} from './util/rTorrentMethodCallUtil';
 
@@ -11,6 +11,7 @@ type MethodCallParameters = Array<string | Buffer | MultiMethodCalls>;
 
 class ClientRequestManager {
   connectionSettings: RTorrentConnectionSettings;
+  isJSONCapable = false;
   isRequestPending = false;
   lastResponseTimestamp = 0;
   pendingRequests: Array<{
@@ -70,7 +71,11 @@ class ClientRequestManager {
             port: this.connectionSettings.port,
           };
 
-    return scgiUtil.methodCall(connectionOptions, methodName, parameters).then(
+    const methodCall = this.isJSONCapable
+      ? methodCallJSON(connectionOptions, methodName, parameters)
+      : methodCallXML(connectionOptions, methodName, parameters);
+
+    return methodCall.then(
       (response) => {
         this.handleRequestEnd();
         return response;
diff --git a/server/services/rTorrent/util/scgiUtil.ts b/server/services/rTorrent/util/scgiUtil.ts
index 8d7aa0e5..961decf6 100644
--- a/server/services/rTorrent/util/scgiUtil.ts
+++ b/server/services/rTorrent/util/scgiUtil.ts
@@ -1,6 +1,11 @@
 import net from 'net';
+
 import deserializer from './XMLRPCDeserializer';
-import serializer, {XMLRPCValue} from './XMLRPCSerializer';
+import serializer from './XMLRPCSerializer';
+import {RPCError} from '../types/RPCError';
+
+import type {MultiMethodCalls} from './rTorrentMethodCallUtil';
+import type {XMLRPCValue} from './XMLRPCSerializer';
 
 const NULL_CHAR = String.fromCharCode(0);
 
@@ -13,7 +18,7 @@ const bufferStream = (stream: net.Socket): Promise<string> => {
   });
 };
 
-const methodCall = (options: net.NetConnectOpts, methodName: string, params: XMLRPCValue[]) =>
+export const methodCallXML = (options: net.NetConnectOpts, methodName: string, params: XMLRPCValue[]) =>
   // TODO: better typings
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   new Promise<any>((resolve, reject) => {
@@ -39,4 +44,60 @@ const methodCall = (options: net.NetConnectOpts, methodName: string, params: XML
       .then(resolve, reject);
   });
 
-export default {methodCall};
+export const methodCallJSON = (options: net.NetConnectOpts, methodName: string, params: unknown[]) =>
+  // TODO: better typings
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  new Promise<any>((resolve, reject) => {
+    const stream = net.connect(options);
+    const request =
+      methodName == 'system.multicall'
+        ? (params[0] as MultiMethodCalls).map((call) => ({
+            jsonrpc: '2.0',
+            id: null,
+            method: call.methodName,
+            params: call.params,
+          }))
+        : {
+            jsonrpc: '2.0',
+            id: null,
+            method: methodName,
+            params,
+          };
+
+    const json = JSON.stringify(request);
+    const jsonLength = Buffer.byteLength(json, 'utf8');
+
+    stream.on('error', reject);
+    stream.setEncoding('UTF8');
+
+    const headerItems = [
+      `CONTENT_LENGTH${NULL_CHAR}${jsonLength}${NULL_CHAR}`,
+      `CONTENT_TYPE${NULL_CHAR}application/json${NULL_CHAR}`,
+      `SCGI${NULL_CHAR}1${NULL_CHAR}`,
+    ];
+
+    const headerLength = headerItems.reduce((accumulator, headerItem) => accumulator + headerItem.length, 0);
+
+    stream.end(`${headerLength}:${headerItems.join('')},${json}`);
+
+    bufferStream(stream)
+      .then((data: string) => {
+        const jsonResponse = JSON.parse(data.slice(data.lastIndexOf('\n')));
+        if (Array.isArray(jsonResponse)) {
+          return jsonResponse.map((response) => {
+            if (response.result == null) {
+              const {code, message} = response.error || {};
+              throw RPCError(code, message);
+            }
+            return response.result;
+          });
+        } else {
+          if (jsonResponse.result == null) {
+            const {code, message} = jsonResponse.error || {};
+            throw RPCError(code, message);
+          }
+          return jsonResponse.result;
+        }
+      })
+      .then(resolve, reject);
+  });