net: Listen("tcp", ":123456789") works

[pierrre]

CL: https://golang.org/cl/12213

Go version: go1.4.2 linux/amd64 (same result with Go 1.5beta1)
My code:

package main

import (
    "fmt"
    "net"
)

func main() {
    l, err := net.Listen("tcp", ":123456789")
    if err != nil {
        panic(err)
    }
    fmt.Println(l.Addr())
}

It prints: [::]:52501 (always this port)
What I expected: it should return an error.

If I use port ":66666", it prints: panic: listen tcp: invalid port 66666

[jnjackins]

This will happen for any ports higher than 0xFFFFFF. dtoi fails for inputs larger than that, which causes parsePort to take a different error path.

The error message for ports >= 0xFFFFFF (16777215) on darwin is a bit more reasonable:

panic: listen tcp: lookup tcp/16777215: nodename nor servname provided, or not known

[jnjackins]

Actually, I get a decent error message on linux as well:

$ uname -a
Linux foo.bar.com 2.6.32-504.23.4.el6.x86_64 #1 SMP Fri May 29 10:16:43 EDT 2015 x86_64 x86_64 x86_64 GNU/Linux
$ ./test2 
panic: listen tcp: unknown port tcp/16777215

[jnjackins]

I mailed https://go-review.googlesource.com/#/c/12213, although I don't know if it's an acceptable fix and I'm sure it's not important for go1.5.

[jnjackins]

Oh, I've realized now that I read your message wrong from the beginning. I thought you were getting a strange error message, but you're not getting an error at all for the higher port. I wasn't reproducing it correctly, as I was cross-compiling for linux from darwin. I see the real issue now when I compile and run from linux.

[gopherbot]

CL https://golang.org/cl/12213 mentions this issue.

[mikioh]

@jnjackins,

Please open a new issue for consistent error messages. This issue needs to focus on the behavior of Listen w/ invalid arguments.

[gopherbot]

CL https://golang.org/cl/12447 mentions this issue.