SSH2Stream: fix decompression of large packets

When a zlib decompression stream exceeds the highWaterMark, the
flush() callback won't be called until all of the current
uncompressed data is read.

lib/ssh.js

@@ -547,8 +547,18 @@ SSH2Stream.prototype._transform = function(chunk, encoding, callback, decomp) {
         if (!decomp) {
           debug('DEBUG: Parser: Decompressing');
           decompress.instance.write(instate.payload);
-          decompress.instance.flush(Z_PARTIAL_FLUSH, function() {
-            instate.payload = decompress.instance.read();
+          var decompBuf = [];
+          var decompBufLen = 0;
+          decompress.instance.on('readable', function() {
+            var buf;
+            while (buf = this.read()) {
+              decompBuf.push(buf);
+              decompBufLen += buf.length;
+            }
+          }).flush(Z_PARTIAL_FLUSH, function() {
+            decompress.instance.removeAllListeners('readable');
+            instate.payload = Buffer.concat(decompBuf, decompBufLen);
+            decompBuf = null;
             var nextSlice;
             if (i === chlen)
               nextSlice = EMPTY_BUFFER; // Avoid slicing a zero-length buffer