Trying COMPRESS

imap-core/lib/commands/capability.js

@@ -31,6 +31,7 @@ module.exports = {
             capabilities.push('QUOTA');
 
             capabilities.push('MOVE');
+            capabilities.push('COMPRESS=DEFLATE');
 
             if (this._server.options.maxMessage) {
                 capabilities.push('APPENDLIMIT=' + this._server.options.maxMessage);

imap-core/lib/commands/compress.js

@@ -0,0 +1,56 @@
+'use strict';
+
+const zlib = require('zlib');
+
+// tag COMPRESS DEFLATE
+module.exports = {
+    state: ['Authenticated', 'Selected'],
+
+    schema: [{
+        name: 'mechanism',
+        type: 'string'
+    }],
+
+    handler(command, callback) {
+
+        let mechanism = (command.attributes[0] && command.attributes[0].value || '').toString().toUpperCase().trim();
+
+        if (!mechanism) {
+            return callback(null, {
+                response: 'BAD'
+            });
+        }
+
+        if (mechanism !== 'DEFLATE') {
+            return callback(null, {
+                response: 'BAD',
+                code: 'CANNOT',
+                message: 'Unsupported compression mechanism'
+            });
+        }
+
+        setImmediate(() => {
+            this.compression = true;
+
+            this._deflate = zlib.createDeflateRaw();
+            this._inflate = zlib.createDeflateRaw();
+
+            this._deflate.once('error', err => {
+                this._socket.emit('error', err);
+            });
+
+            this._deflate.pipe(this._socket);
+
+            this.writeStream.unpipe(this._socket);
+            this.writeStream.pipe(this._deflate);
+
+            this._socket.unpipe(this._parser);
+            this._socket.pipe(this._inflate).pipe(this._parser);
+        });
+
+        callback(null, {
+            response: 'OK',
+            message: 'DEFLATE active'
+        });
+    }
+};

imap-core/lib/imap-command.js

@@ -45,7 +45,8 @@ let commands = new Map([
     ['ENABLE', require('./commands/enable')],
     ['GETQUOTAROOT', require('./commands/getquotaroot')],
     ['SETQUOTA', require('./commands/setquota')],
-    ['GETQUOTA', require('./commands/getquota')]
+    ['GETQUOTA', require('./commands/getquota')],
+    ['COMPRESS', require('./commands/compress')]
     /*eslint-enable global-require*/
 ]);
 

imap-core/lib/imap-connection.js

@@ -28,6 +28,10 @@ class IMAPConnection extends EventEmitter {
         // Random session ID, used for logging
         this.id = crypto.randomBytes(9).toString('base64');
 
+        this.compression = false;
+        this._deflate = false;
+        this._inflate = false;
+
         this._server = server;
         this._socket = socket;
 
@@ -118,7 +122,7 @@ class IMAPConnection extends EventEmitter {
      */
     send(payload, callback) {
         if (this._socket && this._socket.writable) {
-            this._socket.write(payload + '\r\n', 'binary', callback);
+            (!this.compression ? this._socket : this._deflate).write(payload + '\r\n', 'binary', callback);
             this._server.logger.debug('[%s] S:', this.id, payload);
         }
     }
@@ -178,6 +182,14 @@ class IMAPConnection extends EventEmitter {
             this._dataStream = null;
         }
 
+        if (this._deflate) {
+            this._deflate = null;
+        }
+
+        if (this._inflate) {
+            this._inflate = null;
+        }
+
         if (this._listenerData) {
             this._listenerData.clear();
         }