Description
At this time, no official x/net package is available to create and use ethernet sockets in Go. I have written a couple of packages which can be used for this purpose, but I'd like to try to create an x/net/ethernet package as an official Go x/net subproject.
My packages can be found at:
Ethernet sockets are useful for low-level networking applications like ARP, LLDP, ATA over Ethernet, and a wide variety of other networking protocols. This package would make use of Linux's raw sockets and the BSD family's BPF to enable this functionality, and I already have working examples for these operating systems in my raw package. Adding support for other operating systems should be possible over time, but I have no personal experience working with ethernet sockets outside of Linux and BSD.
The proposed API could look something like:
package ethernet
// An Ethernet frame, which the Conn and RawConn types marshal
// and unmarshal to transport data
type Frame struct {
// Contains usual Ethernet fields
}
// net.Addr implementation which indicates source or destination
// hardware address of Ethernet frame
type Addr struct {
HardwareAddr net.HardwareAddr
}
func (a *Addr) Network() string
func (a *Addr) String() string
// Protocol identifier used to filter traffic by EtherType
type EtherType uint16
// A net.PacketConn which wraps and unwraps bytes from ethernet
// frames seamlessly.
type Conn struct {}
func Listen(ifi *net.Interface, et EtherType) (*Conn, error)
func (c *Conn) Close() error
func (c *Conn) LocalAddr() net.Addr
func (c *Conn) ReadFrom(b []byte) (int, net.Addr, error)
func (c *Conn) SetBPF(filter []bpf.RawInstruction) error
func (c *Conn) SetDeadline(t time.Time) error
func (c *Conn) SetReadDeadline(t time.Time) error
func (c *Conn) SetWriteDeadline(t time.Time) error
func (c *Conn) WriteTo(b []byte, addr net.Addr) (int, error)
// A modified Conn which returns all Ethernet frame data on incoming
// frames and enables writing arbitrary outgoing frames.
type RawConn struct{}
func ListenRaw(ifi *net.Interface, et EtherType) (*RawConn, error)
func (c *RawConn) Close() error
func (c *RawConn) ReadFrom(b []byte) (f *Frame, p []byte, error)
func (c *RawConn) SetBPF(filter []bpf.RawInstruction) error
func (c *RawConn) SetDeadline(t time.Time) error
func (c *RawConn) SetReadDeadline(t time.Time) error
func (c *RawConn) SetWriteDeadline(t time.Time) error
func (c *RawConn) WriteTo(f *Frame, b []byte) error
I am curious if 802.11Q VLAN tags should be included in this package. In general, the operating system seamlessly handles adding and removing VLAN tags as needed, so it may not be necessary, but could also be nice to have.
In addition, since the runtime network poller is not accessible outside of package net at the moment, the SetDeadline methods may just return an error until implemented later. See my other proposal at #15984 .
If implemented, this package would fix #8432.
Thanks for your time, and please feel free to ask for clarification if needed.