server: also modify torrent file on "Set Tracker"

Changes in v2:

- sessionPath does not belong to torrentListPropMap. Don't use it.
- Instead, request sessionPath when we want to do file ops on torrents.

package-lock.json

@@ -3298,6 +3298,14 @@
         "tweetnacl": "^0.14.3"
       }
     },
+    "bencode": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/bencode/-/bencode-2.0.1.tgz",
+      "integrity": "sha512-2uhEl8FdjSBUyb69qDTgOEeeqDTa+n3yMQzLW0cOzNf1Ow5bwcg3idf+qsWisIKRH8Bk8oC7UXL8irRcPA8ZEQ==",
+      "requires": {
+        "safe-buffer": "^5.1.1"
+      }
+    },
     "big.js": {
       "version": "5.2.2",
       "resolved": "https://registry.npmjs.org/big.js/-/big.js-5.2.2.tgz",
@@ -14493,6 +14501,14 @@
       "resolved": "https://registry.npmjs.org/safer-buffer/-/safer-buffer-2.1.2.tgz",
       "integrity": "sha512-YZo3K82SD7Riyi0E1EQPojLz7kpepnSQI9IyPbHHg1XXXevb5dJI7tpyN2ADxGcQbHG7vcyRHk0cbwqcQriUtg=="
     },
+    "sanitize-filename": {
+      "version": "1.6.3",
+      "resolved": "https://registry.npmjs.org/sanitize-filename/-/sanitize-filename-1.6.3.tgz",
+      "integrity": "sha512-y/52Mcy7aw3gRm7IrcGDFx/bCk4AhRh2eI9luHOQM86nZsqwiRkkq2GekHXBBD+SmPidc8i2PqtYZl+pWJ8Oeg==",
+      "requires": {
+        "truncate-utf8-bytes": "^1.0.0"
+      }
+    },
     "sass-graph": {
       "version": "2.2.5",
       "resolved": "https://registry.npmjs.org/sass-graph/-/sass-graph-2.2.5.tgz",
@@ -16198,6 +16214,14 @@
         "glob": "^7.1.2"
       }
     },
+    "truncate-utf8-bytes": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/truncate-utf8-bytes/-/truncate-utf8-bytes-1.0.2.tgz",
+      "integrity": "sha1-QFkjkJWS1W94pYGENLC3hInKXys=",
+      "requires": {
+        "utf8-byte-length": "^1.0.1"
+      }
+    },
     "tsconfig-paths": {
       "version": "3.9.0",
       "resolved": "https://registry.npmjs.org/tsconfig-paths/-/tsconfig-paths-3.9.0.tgz",
@@ -16917,6 +16941,11 @@
       "integrity": "sha512-cwESVXlO3url9YWlFW/TA9cshCEhtu7IKJ/p5soJ/gGpj7vbvFrAY/eIioQ6Dw23KjZhYgiIo8HOs1nQ2vr/oQ==",
       "dev": true
     },
+    "utf8-byte-length": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/utf8-byte-length/-/utf8-byte-length-1.0.4.tgz",
+      "integrity": "sha1-9F8VDExm7uloGGUFq5P8u4rWv2E="
+    },
     "util": {
       "version": "0.11.1",
       "resolved": "https://registry.npmjs.org/util/-/util-0.11.1.tgz",

package.json

@@ -49,6 +49,7 @@
     "axios": "^0.20.0",
     "babel-eslint": "^10.1.0",
     "babel-loader": "^8.0.6",
+    "bencode": "^2.0.1",
     "body-parser": "^1.18.3",
     "case-sensitive-paths-webpack-plugin": "2.3.0",
     "chalk": "^4.1.0",
@@ -99,6 +100,7 @@
     "react-transition-group": "^4.4.1",
     "ress": "^3.0.0",
     "run-series": "^1.1.6",
+    "sanitize-filename": "^1.6.3",
     "sass-loader": "^10.0.1",
     "saxen": "^8.1.2",
     "source-map-loader": "^1.1.0",

server/models/ClientRequest.js

@@ -380,6 +380,10 @@ class ClientRequest {
       this.requests.push(getMethodCall('d.close', [hash]));
     });
   }
+
+  getSessionPath() {
+    this.requests.push(getMethodCall('session.path'));
+  }
 }
 
 module.exports = ClientRequest;

server/models/client.js

@@ -1,5 +1,6 @@
 const fs = require('fs');
 const path = require('path');
+const sanitize = require('sanitize-filename');
 const series = require('run-series');
 const tar = require('tar-stream');
 
@@ -10,6 +11,7 @@ const fileUtil = require('../util/fileUtil');
 const settings = require('./settings');
 const torrentFilePropsMap = require('../../shared/constants/torrentFilePropsMap');
 const torrentPeerPropsMap = require('../../shared/constants/torrentPeerPropsMap');
+const torrentFileUtil = require('../util/torrentFileUtil');
 const torrentStatusMap = require('../../shared/constants/torrentStatusMap');
 const torrentTrackerPropsMap = require('../../shared/constants/torrentTrackerPropsMap');
 
@@ -383,7 +385,23 @@ const client = {
   setTracker(user, services, data, callback) {
     const request = new ClientRequest(user, services);
 
+    request.getSessionPath();
     request.setTracker(data);
+    request.postProcess((response) => {
+      // Modify tracker URL in torrent files
+      const {tracker, hashes} = data;
+      const sessionPath = `${response.shift()}`;
+
+      if (typeof sessionPath === 'string') {
+        // Deduplicate hashes via Set() to avoid file ops on the same files
+        [...new Set(hashes)].forEach((hash) => {
+          const torrent = path.join(sessionPath, sanitize(`${hash}.torrent`));
+          torrentFileUtil.setTracker(torrent, tracker);
+        });
+      }
+
+      return response;
+    });
     request.onComplete((response, error) => {
       // Fetch the latest torrent list to re-index trackerURI.
       services.torrentService.fetchTorrentList();

server/util/torrentFileUtil.js

@@ -0,0 +1,24 @@
+const bencode = require('bencode');
+const fs = require('fs');
+
+const setTracker = (torrent, tracker) => {
+  fs.readFile(torrent, (err, data) => {
+    if (err) {
+      return;
+    }
+
+    const torrentData = bencode.decode(data);
+
+    if (torrentData.announce != null) {
+      torrentData.announce = Buffer.from(tracker);
+
+      fs.writeFileSync(torrent, bencode.encode(torrentData));
+    }
+  });
+};
+
+const torrentFileUtil = {
+  setTracker,
+};
+
+module.exports = torrentFileUtil;