Select on connection close channel to prevent sending to a closed connection

[antoniomika]

Recent error found in demo instance:

panic: send on closed channel

goroutine 4128 [running]:
main.main.func4.1(0xc00024f380, 0xc000150880)
	/usr/local/go/src/github.com/antoniomika/sish/main.go:152 +0xa1
created by main.main.func4
	/usr/local/go/src/github.com/antoniomika/sish/main.go:142 +0x2d2

In regards to this change:

sish/main.go

Lines 142 to 156 in cc916eb

	go func() {
	time.Sleep(1 * time.Second)
	count := 0
	holderConn.Listeners.Range(func(key, value interface{}) bool {
	count++
	return true
	})
	if count == 0 {
	holderConn.Messages <- "No forwarding requests sent. Closing connection."
	time.Sleep(1 * time.Millisecond)
	holderConn.CleanUp(state)
	}
	}()

A quick fix for this would be to change this function to have

select {
case <-holderConn.Close:
	return
default:
	holderConn.Messages <- "No forwarding requests sent. Closing connection."
	time.Sleep(1 * time.Millisecond)
	holderConn.CleanUp(state)
}

or similar. A quick fix in the meantime would be to start the process with -sish.cleanupunbound=false

[antoniomika]

Resolved by: afba880