MySQL Bugs: #83649: IPv6 connections do not work

Bug #83649	IPv6 connections do not work
Submitted:	2 Nov 2016 11:11	Modified:	15 Oct 2019 7:50
Reporter:	Michiel Hazelhof	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / NET	Severity:	S1 (Critical)
Version:	7.0.6m5	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	ipv6

Description:
We are lucky enough to have a few connections which are IPv6 only, unfortunately this doesn't play well with the .net connector.

The connection is made via hostname which resolves to both IPv4 and a IPv6 addresses (obviously only the IPv6 is available for the machines in question).

Other SQL tools can connect from the IPv6 only connection to the same database server, the problem appears to reside exclusively in the .net connector.

How to repeat:
Use a computer with both IPv4 and IPv6 connectivity and simply disable IPv4 or a machine on a IPv6 only connection (hard to come by).

Hello  Michiel Hazelhof,

Thank you for the bug report.
Verified as described.

Thanks,
Chiranjeevi.

Temporary fix, not the greatest (I *hope* that TcpClient should be able to handle it just by the hostname, but apperantely I cannot find the correct settings to do so).

        private static Stream GetTcpStream(MySqlConnectionStringBuilder settings)
        {
            IPHostEntry host = Dns.GetHostEntry(settings.Server);
            foreach (IPAddress ipAddress in host.AddressList)
            {
                if (ipAddress.AddressFamily != AddressFamily.InterNetwork && ipAddress.AddressFamily != AddressFamily.InterNetworkV6) continue;

                TcpClient client = new TcpClient(ipAddress.AddressFamily);
                Task task = client.ConnectAsync(settings.Server, (int)settings.Port);

                if (!task.Wait(((int)settings.ConnectionTimeout * 1000)))
                    throw new MySqlException(Resources.Timeout);
                return client.GetStream();
                //TODO:  reimplement or remove keepalive
            }

            throw new MySqlConversionException(Resources.UnableToConnectToHost);
        }

Quick fix to support ip based hosts:

            IPAddress parsed;
            IPAddress.TryParse(settings.Server, out parsed);
            IPHostEntry host = parsed != null ? new IPHostEntry { AddressList = new[] { parsed } } : Dns.GetHostEntry(settings.Server);

Should this bug now be closed because it's fixed in 8.0.18?

https://dev.mysql.com/doc/relnotes/connector-net/en/news-8-0-18.html

> Connector/NET now supports IPV6 connections made using the classic MySQL protocol when the operating system on the server host also supports IPV6. (Bug #29682333)

Verified working, can be closed