Add initial version of querying by hash prefix

src/app.js

@@ -10,6 +10,7 @@ var loggerMiddleware = require('./middleware/logger.js');
 // Routes
 var getSkipSegments = require('./routes/getSkipSegments.js').endpoint;
 var postSkipSegments = require('./routes/postSkipSegments.js');
+var getSkipSegmentsByHash = require('./routes/getSkipSegmentsByHash.js');
 var voteOnSponsorTime = require('./routes/voteOnSponsorTime.js');
 var viewedVideoSponsorTime = require('./routes/viewedVideoSponsorTime.js');
 var setUsername = require('./routes/setUsername.js');
@@ -48,6 +49,9 @@ app.post('/api/postVideoSponsorTimes', oldSubmitSponsorTimes);
 app.get('/api/skipSegments', getSkipSegments);
 app.post('/api/skipSegments', postSkipSegments);
 
+// add the privacy protecting skip segments functions
+app.get('/api/skipSegments/:prefix', getSkipSegmentsByHash);
+
 //voting endpoint
 app.get('/api/voteOnSponsorTime', voteOnSponsorTime);
 app.post('/api/voteOnSponsorTime', voteOnSponsorTime);

src/databases/databases.js

@@ -26,6 +26,10 @@ if (config.createDatabaseIfNotExist && !config.readOnly) {
 
 // Upgrade database if required
 if (!config.readOnly) {
+  // Register hashing function needed for running database upgrade
+  db.function("sha256", function (string) {
+    return require('crypto').createHash("sha256").update(string).digest("hex");
+  });
   ugradeDB(db, "sponsorTimes");
   ugradeDB(privateDB, "private")
 }

src/routes/getSkipSegmentsByHash.js

@@ -0,0 +1,69 @@
+const config = require('../config.js');
+const { db, privateDB } = require('../databases/databases.js');
+
+const getHash = require('../utils/getHash.js');
+const getIP = require('../utils/getIP.js');
+
+/**
+ * @typedef {Object} Segment
+ * @property {string} videoID YouTube video ID the segment is meant for
+ * @property {number[]} segment Tuple of start and end times in seconds
+ * @property {string} category Category of content to skip
+ * @property {string} UUID Unique identifier for the specific segment
+ */
+
+/**
+ * @param {string} prefix Lowercased hexadecimal hash prefix
+ * @param {string} hashedIP Custom hash of the visitor’s IP address
+ * @returns {Segment[]}
+ */
+function getSkipSegmentsByHash(prefix, hashedIP) {
+    /**
+     * @constant
+     * @type {Segment[]}
+     * @default
+     */
+    const segments = [];
+
+    const rows = db.prepare('SELECT videoID, startTime, endTime, UUID, category, shadowHidden FROM sponsorTimes WHERE votes >= -1 AND hashedVideoID LIKE ? ORDER BY startTime')
+            .all(prefix + '%');
+
+    const onlyForCurrentUser = privateDB.prepare('SELECT videoID FROM sponsorTimes WHERE hashedIP = ?').all(hashedIP).map(row => row.videoID);
+
+    for (const row of rows) {
+        /** @TODO check if this logic does what is expected. */
+        if (row.shadowHidden === 1 && onlyForCurrentUser.indexOf(row.videoID) === -1) {
+            // The current visitor’s IP did not submit for the current video.
+            // Do not send shadowHidden segments to them.
+            continue;
+        }
+
+        segments.push({
+            videoID: row.videoID,
+            segment: [row.startTime, row.endTime],
+            category: row.category,
+            UUID: row.UUID
+        });
+    }
+
+    return segments;
+}
+
+const minimumPrefix = config.minimumPrefix || '3';
+const maximumPrefix = config.maximumPrefix || '32'; // Half the hash.
+const prefixChecker = new RegExp('^[\\dA-F]{' + minimumPrefix + ',' + maximumPrefix + '}$', 'i');
+
+module.exports = async function (req, res) {
+    if (!prefixChecker.test(req.params.prefix)) {
+        res.sendStatus(400).end(); // Exit early on faulty prefix
+    }
+
+    const segments = getSkipSegmentsByHash(
+        req.params.prefix.toLowerCase(),
+        getHash(getIP(req) + config.globalSalt)
+    );
+
+    if (segments) {
+        res.send(segments)
+    }
+}