Merge pull request #1004 from sidorares/fix/session-track

Fix crashing when session info packet does not start with length-coded string

lib/constants/session_track.js

@@ -0,0 +1,11 @@
+'use strict';
+
+exports.SYSTEM_VARIABLES = 0;
+exports.SCHEMA = 1;
+exports.STATE_CHANGE = 2;
+exports.STATE_GTIDS = 3;
+exports.TRANSACTION_CHARACTERISTICS = 4;
+exports.TRANSACTION_STATE = 5;
+
+exports.FIRST_KEY = exports.SYSTEM_VARIABLES;
+exports.LAST_KEY = exports.TRANSACTION_STATE;

lib/packets/resultset_header.js

@@ -36,7 +36,9 @@ class ResultSetHeader {
     }
     let stateChanges = null;
     if (isSet('SESSION_TRACK') && packet.offset < packet.end) {
+      const sessionInfoTypes = require('../constants/session_track.js');
       this.info = packet.readLengthCodedString(encoding);
+
       if (this.serverStatus && ServerSatusFlags.SERVER_SESSION_STATE_CHANGED) {
         // session change info record - see
         // https://dev.mysql.com/doc/internals/en/packet-OK_Packet.html#cs-sect-packet-ok-sessioninfo
@@ -48,31 +50,30 @@ class ResultSetHeader {
           stateChanges = {
             systemVariables: {},
             schema: null,
-            // gtids: {},
             trackStateChange: null
           };
         }
         while (packet.offset < end) {
           type = packet.readInt8();
           len = packet.readLengthCodedNumber();
           stateEnd = packet.offset + len;
-          key = packet.readLengthCodedString(encoding);
-          if (type === 0) {
+          if (type === sessionInfoTypes.SYSTEM_VARIABLES) {
+            key = packet.readLengthCodedString(encoding);
             const val = packet.readLengthCodedString(encoding);
             stateChanges.systemVariables[key] = val;
             if (key === 'character_set_client') {
               const charsetNumber = EncodingToCharset[val];
               connection.config.charsetNumber = charsetNumber;
             }
-          } else if (type === 1) {
-            // TODO double check it's supposed to be the only value, not a list.
+          } else if (type === sessionInfoTypes.SCHEMA) {
+            key = packet.readLengthCodedString(encoding);
             stateChanges.schema = key;
-          } else if (type === 2) {
+          } else if (type === sessionInfoTypes.STATE_CHANGE) {
             stateChanges.trackStateChange = packet.readLengthCodedString(
               encoding
             );
           } else {
-            // GTIDs (type == 3) or unknown type - just skip for now
+            // unsupported session track type. For now just ignore
           }
           packet.offset = stateEnd;
         }

test/unit/packets/test-ok-sessiontrack.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const assert = require('assert');
+const Packet = require('../../../lib/packets/packet');
+const ResultSetHeader = require('../../../lib/packets/resultset_header.js');
+const clientConstants = require('../../../lib/constants/client');
+
+const mockConnection = {
+  config: {},
+  serverEncoding: 'utf8',
+  _handshakePacket: {
+    capabilityFlags: clientConstants.PROTOCOL_41 + clientConstants.SESSION_TRACK
+  }
+};
+
+const mkpacket = str => {
+  const buf = Buffer.from(str.split(/[ \n]+/).join(''), 'hex');
+  return new Packet(0, buf, 0, buf.length);
+};
+
+// regression examples from https://github.com/sidorares/node-mysql2/issues/989
+
+assert.doesNotThrow(() => {
+  const packet = mkpacket(
+    `1b 00 00 01
+           00 
+           01 fe 65 96 fc 02 00 00 00 00 03 40 00 00 00 0a 14 08 fe 60 63 9b 05 00 00 00
+          `
+  );
+  new ResultSetHeader(packet, mockConnection);
+});
+
+assert.doesNotThrow(() => {
+  const packet = mkpacket(
+    `13 00 00 01 00 01 00 02 40 00 00 00 0a 14 08 fe 18 25 e7 06 00 00 00`
+  );
+  new ResultSetHeader(packet, mockConnection);
+});