GRPC port forwarding hangs when using mysql connection

[balajiv113]

Description

Steps to reproduce

• Run limactl start --name=lima-vz --vm-type=vz --mount-type=virtiofs template://docker
• Run docker run --detach --name mariadb -p 127.0.0.1:10099:3606 --env MARIADB_DATABASE=db --env MARIADB_ROOT_PASSWORD=root mariadb:latest --port 3606
• Run mysql -uroot -proot --database=db --host=127.0.0.1 --port=10099 -e "SHOW TABLES;" from host and notice it hangs
• Same running from guest works

Note: Identified this issue by running ddev tests

[nirs]

@balajiv113 can this be related to #2970?

[balajiv113]

I don't think so, as its TCP connection in our case

What's happening with mysql is,
As soon connection is established,

• Host accepts a TCP connection
• Starts a tunnel
• Sends empty data via tunnel (Implemented now, to start tunnel on guest as well)
• Once tunnel msg is received on guest, it does a dial
• Start io.copy in guest. For some reason this immediately fails with no error but just says 0 read and error is nil

I have done a change to support retry in these cases
master...balajiv113:lima:grpc-hangs

This works but need to see why it's failing in first place