V2 Netbird integration - UDP MIMO/SIMO, ICMPv6, DHCPv6 implementations (#106)

* begin adding udp.MuxHandler * add udp MuxHandlerSIMO/MIMO * add tcp rx shutdown * icmpv6 client * icmpv6 Client shared NDP/Echo preparation * icmpv6 client ndp/echo split * icmpv6 client ndp/echo split done * icmpv6 adjustments * add dhcpv6 stubs * dhcpv4 preliminary revision * add dns.NextLabel * dns label name tweaks * dns begin work on TCP client * add dnstcp package * apply gofmt changes * add udp mux tests * clean up, remove StackBig for now * remove dnstcp so as to merged confident parts and we continue dnstcp work elsewhere
2026-09-11 00:59:30 +00:00 · 2026-05-10 12:16:30 -03:00
parent bdbd38ab44
commit 7d5830d7ab
22 changed files with 2785 additions and 75 deletions
@@ -0,0 +1,136 @@
+package icmpv6
+
+import (
+	"github.com/soypat/lneto"
+	"github.com/soypat/lneto/internal"
+)
+
+type ndpCache struct {
+	entries []ndpEntry
+}
+
+// ndpEntry maps an IPv6 address to a MAC. Designed for compactness: 24 bytes.
+type ndpEntry struct {
+	addr  [16]byte
+	mac   [6]byte
+	age   uint8
+	flags ndpFlags
+}
+
+type ndpFlags uint8
+
+// unset ndpFlagInUse to signal the entry can be acquired for a new query.
+const (
+	ndpFlagInUse                   ndpFlags = 1 << iota
+	ndpFlagPendingResponse                  // received a NS for our addr; must send NA
+	ndpFlagIncomplete                       // query in flight; MAC not yet resolved
+	ndpFlagIncompletePendingQuery           // NS not yet transmitted
+	ndpFlagPriority                         // user query; evicted last
+	ndpFlagResolveTriggersCallback          // call onresolve when MAC is learned
+)
+
+func (f ndpFlags) hasAny(bits ndpFlags) bool { return f&bits != 0 }
+
+func (e *ndpEntry) use(mac [6]byte, addr [16]byte, flags ndpFlags) {
+	e.flags = ndpFlagInUse | flags
+	e.addr = addr
+	e.age = 0
+	e.mac = mac
+}
+
+func (e *ndpEntry) destroy() { *e = ndpEntry{} }
+
+func (e *ndpEntry) put(buf []byte, ourAddr [16]byte, ourMAC [6]byte, tp Type) (int, error) {
+	if len(buf) < sizeNDP {
+		return 0, lneto.ErrShortBuffer
+	}
+	buf[0] = uint8(tp)
+	buf[1] = 0
+	buf[2], buf[3] = 0, 0 // checksum zeroed; caller computes it
+	switch tp {
+	case TypeNeighborSolicitation:
+		buf[4], buf[5], buf[6], buf[7] = 0, 0, 0, 0
+		copy(buf[8:24], e.addr[:]) // target = address being queried
+		buf[24] = ndpOptSourceLinkAddr
+		buf[25] = 1 // length in units of 8 bytes
+		copy(buf[26:32], ourMAC[:])
+	case TypeNeighborAdvertisement:
+		buf[4] = 0x60 // S=1 (solicited), O=1 (override)
+		buf[5], buf[6], buf[7] = 0, 0, 0
+		copy(buf[8:24], ourAddr[:]) // target = our address being announced
+		buf[24] = ndpOptTargetLinkAddr
+		buf[25] = 1
+		copy(buf[26:32], ourMAC[:])
+	default:
+		return 0, lneto.ErrUnsupported
+	}
+	return sizeNDP, nil
+}
+
+func (c *ndpCache) ageEntries() {
+	for i := range c.entries {
+		if c.entries[i].flags&ndpFlagInUse != 0 && c.entries[i].age < 255 {
+			c.entries[i].age++
+		}
+	}
+}
+
+func (c *ndpCache) reset(maxLimit int) {
+	internal.SliceReuse(&c.entries, maxLimit)
+	c.entries = c.entries[:cap(c.entries)]
+}
+
+func (c *ndpCache) getNextFlagged(flags ndpFlags) *ndpEntry {
+	for i := range c.entries {
+		f := c.entries[i].flags
+		if f&ndpFlagInUse != 0 && f.hasAny(flags) {
+			return &c.entries[i]
+		}
+	}
+	return nil
+}
+
+func (c *ndpCache) clearFlags(entryHasFlags, clrTheseFlagsIfMatch ndpFlags) {
+	for i := range c.entries {
+		if c.entries[i].flags&entryHasFlags != 0 {
+			c.entries[i].flags &^= clrTheseFlagsIfMatch
+		}
+	}
+}
+
+func (c *ndpCache) Lookup(addr [16]byte) *ndpEntry {
+	for i := range c.entries {
+		if c.entries[i].flags&ndpFlagInUse != 0 && c.entries[i].addr == addr {
+			return &c.entries[i]
+		}
+	}
+	return nil
+}
+
+// acquireNext returns the next available entry, evicting the oldest passive
+// (passively-learned) entry before touching active user queries or pending responses.
+func (c *ndpCache) acquireNext() *ndpEntry {
+	const priorityFlags = ndpFlagPendingResponse | ndpFlagIncomplete | ndpFlagPriority
+	oldest, oldestPassive := 0, -1
+	for i := range c.entries {
+		if c.entries[i].flags&ndpFlagInUse == 0 {
+			oldest = i
+			break
+		}
+		if !c.entries[i].flags.hasAny(priorityFlags) {
+			if oldestPassive < 0 || c.entries[i].age > c.entries[oldestPassive].age {
+				oldestPassive = i
+			}
+		}
+		if c.entries[i].age > c.entries[oldest].age {
+			oldest = i
+		}
+	}
+	if oldestPassive >= 0 && c.entries[oldest].flags&ndpFlagInUse != 0 {
+		oldest = oldestPassive
+	}
+	c.ageEntries()
+	e := &c.entries[oldest]
+	e.destroy()
+	return e
+}