Remove more os.Exit calls and give a more reliable wait for stop function

udp/conn.go

@@ -16,7 +16,7 @@ type EncReader func(
 type Conn interface {
 	Rebind() error
 	LocalAddr() (netip.AddrPort, error)
-	ListenOut(r EncReader)
+	ListenOut(r EncReader) error
 	WriteTo(b []byte, addr netip.AddrPort) error
 	ReloadConfig(c *config.C)
 	SupportsMultipleReaders() bool
@@ -31,8 +31,8 @@ func (NoopConn) Rebind() error {
 func (NoopConn) LocalAddr() (netip.AddrPort, error) {
 	return netip.AddrPort{}, nil
 }
-func (NoopConn) ListenOut(_ EncReader) {
-	return
+func (NoopConn) ListenOut(_ EncReader) error {
+	return nil
 }
 func (NoopConn) SupportsMultipleReaders() bool {
 	return false

udp/udp_darwin.go

@@ -165,7 +165,7 @@ func NewUDPStatsEmitter(udpConns []Conn) func() {
 	return func() {}
 }
 
-func (u *StdConn) ListenOut(r EncReader) {
+func (u *StdConn) ListenOut(r EncReader) error {
 	buffer := make([]byte, MTU)
 
 	for {
@@ -173,8 +173,7 @@ func (u *StdConn) ListenOut(r EncReader) {
 		n, rua, err := u.ReadFromUDPAddrPort(buffer)
 		if err != nil {
 			if errors.Is(err, net.ErrClosed) {
-				u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-				return
+				return err
 			}
 
 			u.l.WithError(err).Error("unexpected udp socket receive error")

udp/udp_generic.go

@@ -10,11 +10,9 @@ package udp
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"net/netip"
-	"time"
 
 	"github.com/sirupsen/logrus"
 	"github.com/slackhq/nebula/config"
@@ -73,25 +71,14 @@ type rawMessage struct {
 	Len uint32
 }
 
-func (u *GenericConn) ListenOut(r EncReader) {
+func (u *GenericConn) ListenOut(r EncReader) error {
 	buffer := make([]byte, MTU)
 
-	var lastRecvErr time.Time
-
 	for {
 		// Just read one packet at a time
 		n, rua, err := u.ReadFromUDPAddrPort(buffer)
 		if err != nil {
-			if errors.Is(err, net.ErrClosed) {
-				u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-				return
-			}
-			// Dampen unexpected message warns to once per minute
-			if lastRecvErr.IsZero() || time.Since(lastRecvErr) > time.Minute {
-				lastRecvErr = time.Now()
-				u.l.WithError(err).Warn("unexpected udp socket receive error")
-			}
-			continue
+			return err
 		}
 
 		r(netip.AddrPortFrom(rua.Addr().Unmap(), rua.Port()), buffer[:n])

udp/udp_linux.go

@@ -171,7 +171,7 @@ func recvmmsg(fd uintptr, msgs []rawMessage) (int, bool, error) {
 	return int(n), true, nil
 }
 
-func (u *StdConn) listenOutSingle(r EncReader) {
+func (u *StdConn) listenOutSingle(r EncReader) error {
 	var err error
 	var n int
 	var from netip.AddrPort
@@ -180,15 +180,14 @@ func (u *StdConn) listenOutSingle(r EncReader) {
 	for {
 		n, from, err = u.udpConn.ReadFromUDPAddrPort(buffer)
 		if err != nil {
-			u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-			return
+			return err
 		}
 		from = netip.AddrPortFrom(from.Addr().Unmap(), from.Port())
 		r(from, buffer[:n])
 	}
 }
 
-func (u *StdConn) listenOutBatch(r EncReader) {
+func (u *StdConn) listenOutBatch(r EncReader) error {
 	var ip netip.Addr
 	var n int
 	var operr error
@@ -205,12 +204,10 @@ func (u *StdConn) listenOutBatch(r EncReader) {
 	for {
 		err := u.rawConn.Read(reader)
 		if err != nil {
-			u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-			return
+			return err
 		}
 		if operr != nil {
-			u.l.WithError(operr).Debug("operr: udp socket is closed, exiting read loop")
-			return
+			return operr
 		}
 
 		for i := 0; i < n; i++ {
@@ -225,14 +222,11 @@ func (u *StdConn) listenOutBatch(r EncReader) {
 	}
 }
 
-func (u *StdConn) ListenOut(r EncReader) {
+func (u *StdConn) ListenOut(r EncReader) error {
 	if u.batch == 1 {
-		//save some ram by not calling PrepareRawMessages for fields we won't use
-		//we could also make this path more common by calling recvmmsg with msgs[:1],
-		//but that's still the recvmmsg syscall, which would be a change
-		u.listenOutSingle(r)
+		return u.listenOutSingle(r)
 	} else {
-		u.listenOutBatch(r)
+		return u.listenOutBatch(r)
 	}
 }
 
@@ -290,7 +284,7 @@ func (u *StdConn) ReloadConfig(c *config.C) {
 }
 
 func (u *StdConn) getMemInfo(meminfo *[unix.SK_MEMINFO_VARS]uint32) error {
-	var vallen uint32 = 4 * unix.SK_MEMINFO_VARS
+	const vallen uint32 = 4 * unix.SK_MEMINFO_VARS
 
 	if u.rawConn == nil {
 		return fmt.Errorf("no UDP connection")

udp/udp_rio_windows.go

@@ -140,7 +140,7 @@ func (u *RIOConn) bind(l *logrus.Logger, sa windows.Sockaddr) error {
 	return nil
 }
 
-func (u *RIOConn) ListenOut(r EncReader) {
+func (u *RIOConn) ListenOut(r EncReader) error {
 	buffer := make([]byte, MTU)
 
 	var lastRecvErr time.Time
@@ -151,8 +151,7 @@ func (u *RIOConn) ListenOut(r EncReader) {
 
 		if err != nil {
 			if errors.Is(err, net.ErrClosed) {
-				u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
-				return
+				return err
 			}
 			// Dampen unexpected message warns to once per minute
 			if lastRecvErr.IsZero() || time.Since(lastRecvErr) > time.Minute {

udp/udp_tester.go

@@ -6,6 +6,7 @@ package udp
 import (
 	"io"
 	"net/netip"
+	"os"
 	"sync/atomic"
 
 	"github.com/sirupsen/logrus"
@@ -106,11 +107,11 @@ func (u *TesterConn) WriteTo(b []byte, addr netip.AddrPort) error {
 	return nil
 }
 
-func (u *TesterConn) ListenOut(r EncReader) {
+func (u *TesterConn) ListenOut(r EncReader) error {
 	for {
 		p, ok := <-u.RxPackets
 		if !ok {
-			return
+			return os.ErrClosed
 		}
 		r(p.From, p.Data)
 	}