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afpacket: add protocol option that can be passed to NewTPacket #135

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Merged
mosajjal merged 1 commit into from
Oct 25, 2025
Merged

afpacket: add protocol option that can be passed to NewTPacket #135

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4 changes: 2 additions & 2 deletions afpacket/afpacket.go
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Original file line number Diff line number Diff line change
Expand Up @@ -164,7 +164,7 @@ func (h *TPacket) bindToInterface(ifaceName string) error {
}
h.ifIndex = ifIndex
s := &unix.SockaddrLinklayer{
Protocol: endian.Htons(uint16(unix.ETH_P_ALL)),
Protocol: endian.Htons(h.opts.protocol),
Ifindex: ifIndex,
}
return unix.Bind(h.fd, s)
Expand Down Expand Up @@ -255,7 +255,7 @@ func NewTPacket(opts ...interface{}) (h *TPacket, err error) {
if h.opts, err = parseOptions(opts...); err != nil {
return nil, err
}
fd, err := unix.Socket(unix.AF_PACKET, int(h.opts.socktype), int(endian.Htons(unix.ETH_P_ALL)))
fd, err := unix.Socket(unix.AF_PACKET, int(h.opts.socktype), int(endian.Htons(h.opts.protocol)))
if err != nil {
return nil, err
}
Expand Down
12 changes: 12 additions & 0 deletions afpacket/options.go
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,14 @@ const (
SocketDgram = OptSocketType(unix.SOCK_DGRAM)
)

// OptProtocol is the protocol that should be received by the socket.
// It can be passed into NewTPacket.
//
// This should be an IEEE 802.3 protocol number in host byte order. To receive
// packets of all protocols, use [unix.ETH_P_ALL] (this is the default). If set
// to zero, no packets are received.
type OptProtocol uint16

// OptInterface is the specific interface to bind to.
// It can be passed into NewTPacket.
type OptInterface string
Expand Down Expand Up @@ -126,6 +134,7 @@ type options struct {
pollTimeout time.Duration
version OptTPacketVersion
socktype OptSocketType
protocol uint16
iface string
}

Expand All @@ -137,6 +146,7 @@ var defaultOpts = options{
pollTimeout: DefaultPollTimeout,
version: TPacketVersionHighestAvailable,
socktype: SocketRaw,
protocol: unix.ETH_P_ALL,
}

func parseOptions(opts ...interface{}) (ret options, err error) {
Expand All @@ -155,6 +165,8 @@ func parseOptions(opts ...interface{}) (ret options, err error) {
ret.pollTimeout = time.Duration(v)
case OptTPacketVersion:
ret.version = v
case OptProtocol:
ret.protocol = uint16(v)
case OptInterface:
ret.iface = string(v)
case OptSocketType:
Expand Down
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