mime decoder

src/haraka-plugins/queue/store_message.js

@@ -3,6 +3,10 @@ exports.register = function () {
   const MessageService = require("../../services/MessageService");
   const path = require('path');
   const DailyStats = require(path.join(__dirname, '../../../db/models/DailyStats'));
+    const MimeDecoder = require(path.join(
+      __dirname,
+      "../../../utils/mimeDecoder"
+    ));
 
     plugin.store_message = async function (next, connection) {
       const transaction = connection.transaction;
@@ -10,24 +14,31 @@ exports.register = function () {
 
       try {
         // Get the body content by processing the message stream buffers
-      let body = '';
+        let body = "";
 
         if (transaction.message_stream && transaction.message_stream._queue) {
           // Convert the buffer to string
-        const fullMessage = Buffer.from(transaction.message_stream._queue[0]).toString('utf8');
+          const fullMessage = Buffer.from(
+            transaction.message_stream._queue[0]
+          ).toString("utf8");
 
           // Split on double newline to separate headers and body
-        const parts = fullMessage.split('\r\n\r\n');
+          const parts = fullMessage.split("\r\n\r\n");
           if (parts.length > 1) {
             // Get everything after the headers
-          body = parts.slice(1).join('\r\n\r\n').trim();
+            body = parts.slice(1).join("\r\n\r\n").trim();
           }
         }
 
+        const rawSubject = transaction.header
+          ? transaction.header.get("subject")
+          : "";
+        const decodedSubject = MimeDecoder.decode(rawSubject);
+
         const messageData = {
           from: transaction.mail_from.address(),
           to: transaction.rcpt_to.map((addr) => addr.address()).join(", "),
-        subject: transaction.header ? transaction.header.get('subject') : '',
+          subject: decodedSubject,
           body: body,
           headers: transaction.header ? transaction.header.headers_decoded : {},
         };
@@ -36,7 +47,10 @@ exports.register = function () {
         await DailyStats.incrementMessageCount();
         next();
       } catch (error) {
-      connection.logerror(plugin, `Failed to store message: ${error.message}`);
+        connection.logerror(
+          plugin,
+          `Failed to store message: ${error.message}`
+        );
         next();
       }
     };

src/utils/mimeDecoder.js

@@ -0,0 +1,87 @@
+// mimeDecoder.js
+
+/**
+ * Decodes MIME encoded-word format strings commonly used in email headers
+ * Handles both Base64 and Quoted-Printable encoding methods
+ * Format: =?charset?encoding?encoded-text?=
+ */
+class MimeDecoder {
+  /**
+   * Decodes a complete MIME encoded-word string
+   * @param {string} str - The MIME encoded string
+   * @returns {string} - The decoded string
+   */
+  static decode(str) {
+    if (!str) return "";
+
+    // Remove any newlines that might be present
+    str = str.replace(/\n/g, "");
+
+    // Regular expression to match MIME encoded-word format
+    const mimeRegex = /=\?([^?]+)\?([BQbq])\?([^?]*)\?=/g;
+
+    return str.replace(mimeRegex, (match, charset, encoding, text) => {
+      try {
+        if (encoding.toUpperCase() === "B") {
+          // Handle Base64 encoding
+          const buffer = Buffer.from(text, "base64");
+          return buffer.toString(this.normalizeCharset(charset));
+        } else if (encoding.toUpperCase() === "Q") {
+          // Handle Quoted-Printable encoding
+          return this.decodeQuotedPrintable(text, charset);
+        }
+        return text;
+      } catch (error) {
+        console.error("Error decoding MIME string:", error);
+        return match; // Return original string if decoding fails
+      }
+    });
+  }
+
+  /**
+   * Normalizes charset names to Node.js compatible charset encodings
+   * @param {string} charset - The charset name from the MIME string
+   * @returns {string} - Normalized charset name
+   */
+  static normalizeCharset(charset) {
+    const charsetMap = {
+      utf8: "utf8",
+      "utf-8": "utf8",
+      "iso-8859-1": "latin1",
+      "iso8859-1": "latin1",
+      "windows-1252": "latin1",
+    };
+
+    return charsetMap[charset.toLowerCase()] || charset;
+  }
+
+  /**
+   * Decodes Quoted-Printable encoded text
+   * @param {string} text - The Quoted-Printable encoded text
+   * @param {string} charset - The character set of the encoded text
+   * @returns {string} - Decoded text
+   */
+  static decodeQuotedPrintable(text, charset) {
+    // Replace underscore with space (per QP spec)
+    text = text.replace(/_/g, " ");
+
+    // Replace hex encoded characters
+    text = text.replace(/=([0-9A-F]{2})/gi, (match, hex) => {
+      try {
+        return Buffer.from(hex, "hex").toString(this.normalizeCharset(charset));
+      } catch (error) {
+        return match;
+      }
+    });
+
+    return text;
+  }
+}
+
+// Example usage:
+/*
+const decodedSubject = MimeDecoder.decode('=?utf-8?B?TUVHQS1FbWFpbGJlc3TDpHRpZ3VuZyBlcmZvcmRlcmxpY2g=?=');
+console.log(decodedSubject); // Outputs: MEGA-Emailbestätigung erforderlich
+*/
+
+module.exports = MimeDecoder;