Rework some things into packages (#489)

udp/udp_generic.go

@@ -0,0 +1,91 @@
+//go:build (!linux || android) && !e2e_testing
+// +build !linux android
+// +build !e2e_testing
+
+// udp_generic implements the nebula UDP interface in pure Go stdlib. This
+// means it can be used on platforms like Darwin and Windows.
+
+package udp
+
+import (
+	"context"
+	"fmt"
+	"net"
+
+	"github.com/sirupsen/logrus"
+	"github.com/slackhq/nebula/config"
+	"github.com/slackhq/nebula/firewall"
+	"github.com/slackhq/nebula/header"
+)
+
+type Conn struct {
+	*net.UDPConn
+	l *logrus.Logger
+}
+
+func NewListener(l *logrus.Logger, ip string, port int, multi bool, batch int) (*Conn, error) {
+	lc := NewListenConfig(multi)
+	pc, err := lc.ListenPacket(context.TODO(), "udp", fmt.Sprintf("%s:%d", ip, port))
+	if err != nil {
+		return nil, err
+	}
+	if uc, ok := pc.(*net.UDPConn); ok {
+		return &Conn{UDPConn: uc, l: l}, nil
+	}
+	return nil, fmt.Errorf("Unexpected PacketConn: %T %#v", pc, pc)
+}
+
+func (uc *Conn) WriteTo(b []byte, addr *Addr) error {
+	_, err := uc.UDPConn.WriteToUDP(b, &net.UDPAddr{IP: addr.IP, Port: int(addr.Port)})
+	return err
+}
+
+func (uc *Conn) LocalAddr() (*Addr, error) {
+	a := uc.UDPConn.LocalAddr()
+
+	switch v := a.(type) {
+	case *net.UDPAddr:
+		addr := &Addr{IP: make([]byte, len(v.IP))}
+		copy(addr.IP, v.IP)
+		addr.Port = uint16(v.Port)
+		return addr, nil
+
+	default:
+		return nil, fmt.Errorf("LocalAddr returned: %#v", a)
+	}
+}
+
+func (u *Conn) ReloadConfig(c *config.C) {
+	// TODO
+}
+
+func NewUDPStatsEmitter(udpConns []*Conn) func() {
+	// No UDP stats for non-linux
+	return func() {}
+}
+
+type rawMessage struct {
+	Len uint32
+}
+
+func (u *Conn) ListenOut(r EncReader, lhf LightHouseHandlerFunc, cache *firewall.ConntrackCacheTicker, q int) {
+	plaintext := make([]byte, MTU)
+	buffer := make([]byte, MTU)
+	h := &header.H{}
+	fwPacket := &firewall.Packet{}
+	udpAddr := &Addr{IP: make([]byte, 16)}
+	nb := make([]byte, 12, 12)
+
+	for {
+		// Just read one packet at a time
+		n, rua, err := u.ReadFromUDP(buffer)
+		if err != nil {
+			u.l.WithError(err).Error("Failed to read packets")
+			continue
+		}
+
+		udpAddr.IP = rua.IP
+		udpAddr.Port = uint16(rua.Port)
+		r(udpAddr, plaintext[:0], buffer[:n], h, fwPacket, lhf, nb, q, cache.Get(u.l))
+	}
+}