nebula/firewall/packet.go

package firewall

import (
	"encoding/json"
	"fmt"
	"net/netip"

	"github.com/slackhq/nebula/iputil"
)

type m = map[string]any

const (
	ProtoAny     = 0  // When we want to handle HOPOPT (0) we can change this, if ever
	PortAny      = 0  // Special value for matching `port: any`
	PortFragment = -1 // Special value for matching `port: fragment`
)

type Packet struct {
	LocalAddr  netip.Addr
	RemoteAddr netip.Addr
	// LocalPort is the destination port for incoming traffic, or the source port for outgoing. Zero for ICMP.
	LocalPort uint16
	// RemotePort is the source port for incoming traffic, or the destination port for outgoing.
	// For ICMP, it's the "identifier". This is only used for connection tracking, actual firewall rules will not filter on ICMP identifier
	RemotePort uint16
	Protocol   uint8
	Fragment   bool

	// pad fills what would otherwise be compiler padding. A Packet with no padding hashes as one
	// block of memory, which makes it a much faster map key. Always zero.
	pad [2]byte
}

func (fp *Packet) Copy() *Packet {
	return &Packet{
		LocalAddr:  fp.LocalAddr,
		RemoteAddr: fp.RemoteAddr,
		LocalPort:  fp.LocalPort,
		RemotePort: fp.RemotePort,
		Protocol:   fp.Protocol,
		Fragment:   fp.Fragment,
	}
}

func (fp Packet) MarshalJSON() ([]byte, error) {
	var proto string
	switch fp.Protocol {
	case iputil.IPProtocolTCP:
		proto = "tcp"
	case iputil.IPProtocolICMP:
		proto = "icmp"
	case iputil.IPProtocolICMPv6:
		proto = "icmpv6"
	case iputil.IPProtocolUDP:
		proto = "udp"
	default:
		proto = fmt.Sprintf("unknown %v", fp.Protocol)
	}
	return json.Marshal(m{
		"LocalAddr":  fp.LocalAddr.String(),
		"RemoteAddr": fp.RemoteAddr.String(),
		"LocalPort":  fp.LocalPort,
		"RemotePort": fp.RemotePort,
		"Protocol":   proto,
		"Fragment":   fp.Fragment,
	})
}

// ParsedPacket is a Packet plus the parse byproducts the RX path reuses
type ParsedPacket struct {
	Packet
	IPHdrLen int
	// FragAny reports any fragmentation at all: MF flag or nonzero offset for IPv4, a fragment extension header for IPv6.
	// Distinct from Packet.Fragment, which is true only for NON-FIRST fragments
	FragAny bool
}