Server: PROTOCOL_CONNECTION_LOST when connecting with mysqli

We are using mysql2 proxy example and see a fatal PROTOCOL_CONNECTION_LOST exception after several sql queries have successfully executed. MySQL version is 5.7.

My guess is that we are not handling the sequenceId correctly somewhere as we also see Warning: got packets out of order. Expected 2 but received 0.

For testing, the proxy code is as per the vanilla example with the exception that we set the sequencId to 0 in the authCallback and to 1 on query. Here is the full code:

"use strict";

const mysql = require("mysql2");
const ClientFlags = require("mysql2/lib/constants/client.js");

const server = mysql.createServer();
server.listen(3300);

server.on("connection", (conn) => {
  console.log("connection");

  conn.serverHandshake({
    protocolVersion: 10,
    serverVersion: "node.js rocks",
    connectionId: 1234,
    statusFlags: 2,
    characterSet: 8,
    capabilityFlags: 0xffffff,
    authCallback: () => {
      conn.writeOk();
      conn.sequenceId = 0;
    },
  });

  conn.on("field_list", (table, fields) => {
    console.log("field list:", table, fields);
    conn.writeEof();
  });

  const remote = mysql.createConnection({
    user: "root",
    database: "wordpress",
    host: "127.0.0.1",
    password: "supersecret",
    port: 3310,
  });

  conn.on("query", (sql) => {
    console.log(`${sql}\n`);
    conn.sequenceId = 1;
    remote.query(sql, function (err) {
      // overloaded args, either (err, result :object)
      // or (err, rows :array, columns :array)
      if (Array.isArray(arguments[1])) {
        // response to a 'select', 'show' or similar
        const rows = arguments[1],
          columns = arguments[2];
        conn.writeTextResult(rows, columns);
      } else {
        // response to an 'insert', 'update' or 'delete'
        const result = arguments[1];
        conn.writeOk(result);
      }
    });
  });

  conn.on("end", remote.end.bind(remote));
});

Connecting a wordpress site, when loading, it fires a few sql queries and I see:

connection
SELECT @@SESSION.sql_mode

Warning: got packets out of order. Expected 6 but received 0
SET SESSION sql_mode='IGNORE_SPACE,NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION'

Warning: got packets out of order. Expected 2 but received 0
events.js:291
      throw er; // Unhandled 'error' event
      ^

Error: Connection lost: The server closed the connection.
    at Socket.<anonymous> (/Users/VisualStudio/node_modules/mysql2/lib/connection.js:91:31)
    at Socket.emit (events.js:314:20)
    at TCP.<anonymous> (net.js:673:12)
Emitted 'error' event on Connection instance at:
    at Connection._notifyError (/Users/VisualStudio/node_modules/mysql2/lib/connection.js:221:12)
    at Socket.<anonymous> (/Users/VisualStudio/node_modules/mysql2/lib/connection.js:97:12)
    at Socket.emit (events.js:314:20)
    at TCP.<anonymous> (net.js:673:12) {
  fatal: true,

Now, if i reset the sequence id at the end of the remote.query, it gets s lot further (successfully completes multiple sql statements and then fails with the same error. Here is the code with the addition:

conn.on("query", (sql) => {
    console.log(`${sql}\n`);
    conn.sequenceId = 1;
    remote.query(sql, function (err) {
      // overloaded args, either (err, result :object)
      // or (err, rows :array, columns :array)
      if (Array.isArray(arguments[1])) {
        // response to a 'select', 'show' or similar
        const rows = arguments[1],
          columns = arguments[2];
        conn.writeTextResult(rows, columns);
      } else {
        // response to an 'insert', 'update' or 'delete'
        const result = arguments[1];
        conn.writeOk(result);
      }
      conn.sequenceId = 0;
    });
  });

Here is the output when executing with the additional conn.sequenceId = 0;:

connection
SELECT @@SESSION.sql_mode

SET SESSION sql_mode='IGNORE_SPACE,NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION'

Warning: got packets out of order. Expected 2 but received 0
SELECT option_name, option_value FROM wp_options WHERE autoload = 'yes'

SELECT option_value FROM wp_options WHERE option_name = 'WPLANG' LIMIT 1

SELECT * FROM wp_users WHERE user_login = 'ben' LIMIT 1

SELECT user_id, meta_key, meta_value FROM wp_usermeta WHERE user_id IN (1) ORDER BY umeta_id ASC

SELECT option_value FROM wp_options WHERE option_name = 'can_compress_scripts' LIMIT 1

SELECT option_value FROM wp_options WHERE option_name = 'theme_switched' LIMIT 1

SELECT SQL_CALC_FOUND_ROWS  wp_posts.ID FROM wp_posts  WHERE 1=1  AND wp_posts.post_type = 'post' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private')  ORDER BY wp_posts.post_date DESC LIMIT 0, 10

SELECT FOUND_ROWS()

SELECT wp_posts.* FROM wp_posts WHERE ID IN (1)

SELECT  t.*, tt.*, tr.object_id FROM wp_terms AS t  INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id INNER JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id WHERE tt.taxonomy IN ('category', 'post_tag', 'post_format') AND tr.object_id IN (1) ORDER BY t.name ASC 

SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (1) ORDER BY meta_id ASC

SELECT option_value FROM wp_options WHERE option_name = '_site_transient_update_plugins' LIMIT 1

SELECT option_value FROM wp_options WHERE option_name = '_site_transient_update_themes' LIMIT 1

SELECT option_value FROM wp_options WHERE option_name = '_site_transient_update_core' LIMIT 1


                SELECT comment_approved, COUNT( * ) AS total
                FROM wp_comments

                GROUP BY comment_approved


SELECT * FROM wp_posts  WHERE (post_type = 'page' AND post_status = 'publish')     ORDER BY menu_order,wp_posts.post_title ASC

SELECT   wp_posts.ID FROM wp_posts  WHERE 1=1  AND wp_posts.post_type = 'post' AND ((wp_posts.post_status = 'publish'))  ORDER BY wp_posts.post_date DESC LIMIT 0, 5

SELECT  wp_comments.comment_ID FROM wp_comments JOIN wp_posts ON wp_posts.ID = wp_comments.comment_post_ID WHERE ( comment_approved = '1' ) AND  wp_posts.post_status IN ('publish')  ORDER BY wp_comments.comment_date_gmt DESC LIMIT 0,5

SELECT wp_comments.* FROM wp_comments WHERE comment_ID IN (1)

SELECT comment_id, meta_key, meta_value FROM wp_commentmeta WHERE comment_id IN (1) ORDER BY meta_id ASC

SELECT YEAR(post_date) AS `year`, MONTH(post_date) AS `month`, count(ID) as posts FROM wp_posts  WHERE post_type = 'post' AND post_status = 'publish' GROUP BY YEAR(post_date), MONTH(post_date) ORDER BY post_date DESC 

SELECT  t.*, tt.* FROM wp_terms AS t  INNER JOIN wp_term_taxonomy AS tt ON t.term_id = tt.term_id WHERE tt.taxonomy IN ('category') AND tt.count > 0 ORDER BY t.name ASC 

SELECT term_id, meta_key, meta_value FROM wp_termmeta WHERE term_id IN (1) ORDER BY meta_id ASC

events.js:291
      throw er; // Unhandled 'error' event
      ^

Error: Connection lost: The server closed the connection.
    at Socket.<anonymous> (/Users/VisualStudio/node_modules/mysql2/lib/connection.js:91:31)
    at Socket.emit (events.js:314:20)
    at TCP.<anonymous> (net.js:673:12)
Emitted 'error' event on Connection instance at:
    at Connection._notifyError (/Users/VisualStudio/node_modules/mysql2/lib/connection.js:221:12)
    at Socket.<anonymous> (/Users/VisualStudio/node_modules/mysql2/lib/connection.js:97:12)
    at Socket.emit (events.js:314:20)
    at TCP.<anonymous> (net.js:673:12) {
  fatal: true,
  code: 'PROTOCOL_CONNECTION_LOST'
}

So it looks like we are not handling the sequenceId’s correctly. We would be very grateful for some advice 👍

[sidorares]

1 is for COM_QUIT - php client might be closing connection ( and 3 is COM_QUERY )

thanks for more debug examples, investigating right now

[sidorares]

Hi @haganbt , thanks for more debug info

simple php mysqli “select 1+1” script worked for me with a server from https://github.com/sidorares/node-mysql2/tree/passthrough-auth-token branch. I’m currently attempting to provide example that would work with master