From ce80e52923fc0caa2de8661fc09dfcc546b94c48 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20Tollk=C3=BChn?= <s.tollkuehn@bnvb-ingenieure.de>
Date: Thu, 22 Oct 2026 17:09:16 +0200
Subject: [PATCH] - fix escaping in ICS generation - add CRLF line endings in
 ICS - add line folding in ICS - fix downloadICS()

---
 assets/launch.js | 141 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 109 insertions(+), 32 deletions(-)

diff --git a/assets/launch.js b/assets/launch.js
index fdaf642..e73df4e 100644
--- a/assets/launch.js
+++ b/assets/launch.js
@@ -889,6 +889,66 @@ function createRoomName(meetingName) {
  * ============================================================
  */
 
+const ICS_LINE_LIMIT = 75;
+
+/*
+ * UTF-8 byte length of a string.
+ */
+function byteLength(text) {
+  let length = 0;
+
+  for (const char of text) {
+    const code = char.codePointAt(0);
+
+    length += code <= 0x7f ? 1 : code <= 0x7ff ? 2 : code <= 0xffff ? 3 : 4;
+  }
+
+  return length;
+}
+
+/*
+ * Escape a text value per RFC 5545: backslash first,
+ * then semicolon and comma, newlines as literal "\n".
+ */
+function escapeICS(text) {
+  return text
+    .replace(/\\/g, "\\\\")
+    .replace(/;/g, "\\;")
+    .replace(/,/g, "\\,")
+    .replace(/\r?\n/g, "\\n");
+}
+
+/*
+ * Fold lines longer than 75 octets into CRLF + space
+ * continuations (RFC 5545).
+ */
+function foldICS(content) {
+  return content
+    .split("\r\n")
+    .map((line) => {
+      if (byteLength(line) <= ICS_LINE_LIMIT) {
+        return line;
+      }
+
+      const parts = [];
+      let current = "";
+
+      for (const char of line) {
+        if (byteLength(current + char) > ICS_LINE_LIMIT) {
+          parts.push(current);
+          current = " " + char;
+        } else {
+          current += char;
+        }
+      }
+
+      parts.push(current);
+
+      return parts.join("\r\n");
+    })
+    .join("\r\n");
+}
+
 function generateICS(meetingName, description, startTime, endTime, organizer) {
   /* Generate a unique room name from the meeting name */
   const roomName = createRoomName(meetingName);
@@ -911,32 +971,39 @@ function generateICS(meetingName, description, startTime, endTime, organizer) {
   const dtStart = formatICSDate(startTime);
   const dtEnd = formatICSDate(endTime);
 
-  /* Build ICS content */
-  const icsContent = `BEGIN:VCALENDAR
-VERSION:2.0
-PRODID:-//BNVB//Jitsi Meeting//EN
-CALSCALE:GREGORIAN
-METHOD:PUBLISH
-BEGIN:VEVENT
-UID:${uid}
-DTSTAMP:${dtStamp}
-DTSTART:${dtStart}
-DTEND:${dtEnd}
-SUMMARY:${meetingName.replace(/,/g, '\\,')}
-DESCRIPTION:${description.replace(/,/g, '\\,').replace(/\n/g, '\\n')}
-LOCATION:${meetingUrl}
-ORGANIZER:MAILTO:${organizer}
-STATUS:CONFIRMED
-URL:${meetingUrl}
-SEQUENCE:0
-TRANSP:OPAQUE
-BEGIN:VALARM
-ACTION:DISPLAY
-DESCRIPTION:Reminder
-TRIGGER:-PT15M
-END:VALARM
-END:VEVENT
-END:VCALENDAR`;
+  /*
+   * One property per line, CRLF endings, folded at
+   * 75 octets (RFC 5545).
+   */
+  const lines = [
+    "BEGIN:VCALENDAR",
+    "VERSION:2.0",
+    `PRODID:-//Jitsi Meeting Launcher//NONSGML (${CONFIG.jitsiLauncher})//EN`,
+    "CALSCALE:GREGORIAN",
+    "METHOD:PUBLISH",
+    "BEGIN:VEVENT",
+    `UID:${uid}`,
+    `DTSTAMP:${dtStamp}`,
+    `DTSTART:${dtStart}`,
+    `DTEND:${dtEnd}`,
+    `SUMMARY:${escapeICS(meetingName)}`,
+    `DESCRIPTION:${escapeICS(description)}`,
+    `LOCATION:${meetingUrl}`,
+    `ORGANIZER:MAILTO:${organizer}`,
+    "STATUS:CONFIRMED",
+    `URL:${meetingUrl}`,
+    "SEQUENCE:0",
+    "TRANSP:OPAQUE",
+    "BEGIN:VALARM",
+    "ACTION:DISPLAY",
+    "DESCRIPTION:Reminder",
+    "TRIGGER:-PT15M",
+    "END:VALARM",
+    "END:VEVENT",
+    "END:VCALENDAR"
+  ];
+
+  const icsContent = foldICS(lines.join("\r\n")) + "\r\n";
 
   return {
     content: icsContent,
@@ -945,10 +1012,22 @@ END:VCALENDAR`;
   };
 }
 
-function downloadICS(content, filename) {
+let icsObjectUrl = null;
+
+/*
+ * Download URL for the ICS content. Revokes the URL of
+ * the previous download.
+ */
+function downloadICS(content) {
   const blob = new Blob([content], { type: 'text/calendar;charset=utf-8' });
-  const url = URL.createObjectURL(blob);
-  return url;
+
+  if (icsObjectUrl !== null) {
+    URL.revokeObjectURL(icsObjectUrl);
+  }
+
+  icsObjectUrl = URL.createObjectURL(blob);
+
+  return icsObjectUrl;
 }
 
 const MINUTES_STEP = 15;
@@ -1159,9 +1238,7 @@ function createMeeting() {
   const icsData = generateICS(meetingName, description || meetingName, startTime, endTime, organizer);
 
   /* Create download link */
-  const blob = new Blob([icsData.content], { type: 'text/calendar;charset=utf-8' });
-  const url = URL.createObjectURL(blob);
-  downloadIcsLink.href = url;
+  downloadIcsLink.href = downloadICS(icsData.content);
   downloadIcsLink.download = `${icsData.roomName}.ics`;
 
   /* Show success message */