golang.org/x/sys/unix: SockAddrInet4 doesn't implement SockAddr?

[kinoshita...@gmail.com]

Hi everyone,

I am sorry for my newbie question.

I want to study law-level socket programming in go using system calls (such as to implement ARP).

For my first trial I have tested the code below named socket.go on Mac OS X 10.11.5 (darwin amd64),

but I got the following error:

# go run packet.go

./socket.go:17: cannot use sa (type unix.SockaddrInet4) as type unix.Sockaddr in argument to unix.Connect:

        unix.SockaddrInet4 does not implement unix.Sockaddr (unix.sockaddr method has pointer receiver)

Whereas $GOPATH/src/golang.org/x/sys/unix/syscall_darwin.go seems not to implement sockaddr for

SockaddrInet4, $GOPATH/src/golang.org/x/sys/unix/syscall_linux.go implements sockaddr for SockaddrInet4.

So I tested the same code on Linux VM (Arch Linux), but I got the same error.

My questions:

- Why my code causes the error in Linux?

- Is it impossible to use unix.SockaddrInet4 as type unix.Sockaddr in darwin?

Thank you.

----

packet.go

----

package main

import (

"fmt"

"os"

"golang.org/x/sys/unix"

)

func main() {

fd, err := unix.Socket(unix.AF_INET, unix.SOCK_RAW, 0)

if err != nil {

fmt.Println("Can't open the socket:", err)

os.Exit(1)

}

sa := unix.SockaddrInet4{Port: 0, Addr: [4]byte{127, 0, 0, 1}}

err = unix.Connect(fd, sa)

if err != nil {

fmt.Println("Can't connect:", err)

os.Exit(1)

}

}

[Michael Jones]

The compilation error is because Connect wants a pointer. Do this instead… 

sa := &unix.SockaddrInet4{Port: 0, Addr: [4]byte{127, 0, 0, 1}}

Michael Jones

michae...@gmail.com

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[Minoru KINOSHITA]

Oh, I can successfully compiled my code both on Darwin and Linux.  Thank you!

--

KINOSHITA Minoru

kinoshita...@gmail.com

2016年6月28日(火) 1:17 Michael Jones <michae...@gmail.com>: