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|
package ndpcmd
import (
"fmt"
"io"
"log"
"net/netip"
"strings"
"github.com/mdlayher/ndp"
)
func printMessage(ll *log.Logger, m ndp.Message, from netip.Addr) {
switch m := m.(type) {
case *ndp.NeighborAdvertisement:
printNA(ll, m, from)
case *ndp.NeighborSolicitation:
printNS(ll, m, from)
case *ndp.RouterAdvertisement:
printRA(ll, m, from)
case *ndp.RouterSolicitation:
printRS(ll, m, from)
default:
ll.Printf("%s %#v", from, m)
}
}
func printRA(ll *log.Logger, ra *ndp.RouterAdvertisement, from netip.Addr) {
var flags []string
if ra.ManagedConfiguration {
flags = append(flags, "managed")
}
if ra.OtherConfiguration {
flags = append(flags, "other")
}
if ra.MobileIPv6HomeAgent {
flags = append(flags, "mobile")
}
if ra.NeighborDiscoveryProxy {
flags = append(flags, "proxy")
}
var s strings.Builder
writef(&s, "router advertisement from: %s:\n", from)
if ra.CurrentHopLimit > 0 {
writef(&s, " - hop limit: %d\n", ra.CurrentHopLimit)
}
if len(flags) > 0 {
writef(&s, " - flags: [%s]\n", strings.Join(flags, ", "))
}
writef(&s, " - preference: %s\n", ra.RouterSelectionPreference)
if ra.RouterLifetime > 0 {
writef(&s, " - router lifetime: %s\n", ra.RouterLifetime)
}
if ra.ReachableTime != 0 {
writef(&s, " - reachable time: %s\n", ra.ReachableTime)
}
if ra.RetransmitTimer != 0 {
writef(&s, " - retransmit timer: %s\n", ra.RetransmitTimer)
}
_, _ = s.WriteString(optionsString(ra.Options))
ll.Print(s.String())
}
func printRS(ll *log.Logger, rs *ndp.RouterSolicitation, from netip.Addr) {
s := fmt.Sprintf(
rsFormat,
from.String(),
)
ll.Print(s + optionsString(rs.Options))
}
const rsFormat = "router solicitation from %s:\n"
func printNA(ll *log.Logger, na *ndp.NeighborAdvertisement, from netip.Addr) {
s := fmt.Sprintf(
naFormat,
from.String(),
na.Router,
na.Solicited,
na.Override,
na.TargetAddress.String(),
)
ll.Print(s + optionsString(na.Options))
}
const naFormat = `neighbor advertisement from %s:
- router: %t
- solicited: %t
- override: %t
- target address: %s
`
func printNS(ll *log.Logger, ns *ndp.NeighborSolicitation, from netip.Addr) {
s := fmt.Sprintf(
nsFormat,
from.String(),
ns.TargetAddress.String(),
)
ll.Print(s + optionsString(ns.Options))
}
const nsFormat = `neighbor solicitation from %s:
- target address: %s
`
func optionsString(options []ndp.Option) string {
if len(options) == 0 {
return ""
}
var s strings.Builder
s.WriteString(" - options:\n")
for _, o := range options {
writef(&s, " - %s\n", optStr(o))
}
return s.String()
}
func optStr(o ndp.Option) string {
switch o := o.(type) {
case *ndp.LinkLayerAddress:
dir := "source"
if o.Direction == ndp.Target {
dir = "target"
}
return fmt.Sprintf("%s link-layer address: %s", dir, o.Addr.String())
case *ndp.MTU:
return fmt.Sprintf("MTU: %d", o.MTU)
case *ndp.PrefixInformation:
var flags []string
if o.OnLink {
flags = append(flags, "on-link")
}
if o.AutonomousAddressConfiguration {
flags = append(flags, "autonomous")
}
return fmt.Sprintf("prefix information: %s/%d, flags: [%s], valid: %s, preferred: %s",
o.Prefix.String(),
o.PrefixLength,
strings.Join(flags, ", "),
o.ValidLifetime,
o.PreferredLifetime,
)
case *ndp.RawOption:
return fmt.Sprintf("type: %03d, value: %v", o.Type, o.Value)
case *ndp.RouteInformation:
return fmt.Sprintf("route information: %s/%d, preference: %s, lifetime: %s",
o.Prefix.String(),
o.PrefixLength,
o.Preference.String(),
o.RouteLifetime,
)
case *ndp.RecursiveDNSServer:
var ss []string
for _, s := range o.Servers {
ss = append(ss, s.String())
}
servers := strings.Join(ss, ", ")
return fmt.Sprintf("recursive DNS servers: lifetime: %s, servers: %s", o.Lifetime, servers)
case *ndp.RAFlagsExtension:
return fmt.Sprintf("RA flags extension: [%# 02x]", o.Flags)
case *ndp.DNSSearchList:
return fmt.Sprintf("DNS search list: lifetime: %s, domain names: %s", o.Lifetime, strings.Join(o.DomainNames, ", "))
case *ndp.CaptivePortal:
return fmt.Sprintf("captive portal: %s", o.URI)
case *ndp.PREF64:
return fmt.Sprintf("pref64: %s, lifetime: %s", o.Prefix, o.Lifetime)
case *ndp.Nonce:
return fmt.Sprintf("nonce: %s", o)
default:
panic(fmt.Sprintf("unrecognized option: %v", o))
}
}
func writef(sw io.StringWriter, format string, a ...any) {
_, _ = sw.WriteString(fmt.Sprintf(format, a...))
}
|
