avoid checking read timeouts continuously

Signed-off-by: Florian Lehner <[email protected]>

Author: florianl

conntrack.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"fmt"
 	"log"
+	"time"
 	"unsafe"
 
 	"github.com/florianl/go-conntrack/internal/unix"
@@ -335,6 +336,13 @@ func (nfct *Nfct) register(ctx context.Context, t Table, groups NetlinkGroup, fi
 	}
 
 	go func() {
+		go func() {
+			// block until context is done
+			<-ctx.Done()
+			// Set the read deadline to a point in the past to interrupt
+			// possible blocking Receive() calls.
+			nfct.Con.SetReadDeadline(time.Now().Add(-1 * time.Second))
+		}()
 		defer func() {
 			if err := nfct.removeFilter(); err != nil {
 				nfct.logger.Printf("could not remove filter: %v", err)
@@ -351,19 +359,17 @@ func (nfct *Nfct) register(ctx context.Context, t Table, groups NetlinkGroup, fi
 				return
 			default:
 			}
-			if err := nfct.setReadTimeout(); err != nil {
-				nfct.logger.Printf("could not set read timeout: %v", err)
-			}
 			reply, err := nfct.Con.Receive()
 			if err != nil {
 				if opError, ok := err.(*netlink.OpError); ok {
 					if opError.Timeout() || opError.Temporary() {
 						continue
 					}
 				}
-				nfct.logger.Printf("receiving error: %v", err)
 				if nfct.errChan != nil {
 					nfct.errChan <- err
+				} else {
+					nfct.logger.Printf("receiving error: %v", err)
 				}
 				return
 			}
@@ -487,9 +493,6 @@ func (nfct *Nfct) send(req netlink.Message) error {
 		return err
 	}
 
-	if err := nfct.setReadTimeout(); err != nil {
-		nfct.logger.Printf("could not set read timeout: %v", err)
-	}
 	return nil
 }
 

conntrack_gteq_1.12.go

@@ -26,14 +26,6 @@ func Open(config *Config) (*Nfct, error) {
 	} else {
 		nfct.logger = config.Logger
 	}
-	if config.ReadTimeout > 0 {
-		nfct.setReadTimeout = func() error {
-			deadline := time.Now().Add(config.ReadTimeout)
-			return nfct.Con.SetReadDeadline(deadline)
-		}
-	} else {
-		nfct.setReadTimeout = func() error { return nil }
-	}
 
 	if config.WriteTimeout > 0 {
 		nfct.setWriteTimeout = func() error {

conntrack_lt_1.12.go

@@ -25,7 +25,6 @@ func Open(config *Config) (*Nfct, error) {
 	} else {
 		nfct.logger = config.Logger
 	}
-	nfct.setReadTimeout = func() error { return nil }
 	nfct.setWriteTimeout = func() error { return nil }
 
 	return &nfct, nil

conntrack_test.go

@@ -160,7 +160,6 @@ func TestCreate(t *testing.T) {
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
 			nfct := &Nfct{}
-			AdjustReadTimeout(nfct, func() error { return nil })
 			AdjustWriteTimeout(nfct, func() error { return nil })
 			nfct.Con = nltest.Dial(func(reqs []netlink.Message) ([]netlink.Message, error) {
 				if len(reqs) == 0 {

export_test.go

@@ -1,5 +1,4 @@
 package conntrack
 
 // Export for testing
-var AdjustReadTimeout = adjustReadTimeout
 var AdjustWriteTimeout = adjustWriteTimeout

types.go

@@ -30,6 +30,10 @@ type Config struct {
 	NetNS int
 
 	// Time till a read action times out - only available for Go >= 1.12
+	//
+	// Deprecated: Cancel the context passed to RegisterFiltered() or Register()
+	// to remove the conntrack gracefully. Setting this value does no longer
+	// have an effect on conntrack.
 	ReadTimeout time.Duration
 
 	// Time till a write action times out - only available for Go >= 1.12
@@ -66,15 +70,9 @@ type Nfct struct {
 
 	errChan chan error
 
-	setReadTimeout  func() error
 	setWriteTimeout func() error
 }
 
-// adjust the ReadTimeout (mostly for testing)
-func adjustReadTimeout(nfct *Nfct, fn func() error) {
-	nfct.setReadTimeout = fn
-}
-
 // adjust the WriteTimeout (mostly for testing)
 func adjustWriteTimeout(nfct *Nfct, fn func() error) {
 	nfct.setWriteTimeout = fn