Allow setting socket timeout on Handle

Signed-off-by: Alessandro Boch <aboch@docker.com>

handle_linux.go

@@ -1,7 +1,9 @@
 package netlink
 
 import (
+	"fmt"
 	"syscall"
+	"time"
 
 	"github.com/vishvananda/netlink/nl"
 	"github.com/vishvananda/netns"
@@ -33,6 +35,29 @@ func NewHandle(nlFamilies ...int) (*Handle, error) {
 	return newHandle(netns.None(), netns.None(), nlFamilies...)
 }
 
+// SetSocketTimeout sets the send and receive timeout for each socket in the
+// netlink handle. Although the socket timeout has granularity of one
+// microsecond, the effective granularity is floored by the kernel timer tick,
+// which default value is four milliseconds.
+func (h *Handle) SetSocketTimeout(to time.Duration) error {
+	if to < time.Microsecond {
+		return fmt.Errorf("invalid timeout, minimul value is %s", time.Microsecond)
+	}
+	tv := syscall.NsecToTimeval(to.Nanoseconds())
+	for _, sh := range h.sockets {
+		fd := sh.Socket.GetFd()
+		err := syscall.SetsockoptTimeval(fd, syscall.SOL_SOCKET, syscall.SO_RCVTIMEO, &tv)
+		if err != nil {
+			return err
+		}
+		err = syscall.SetsockoptTimeval(fd, syscall.SOL_SOCKET, syscall.SO_SNDTIMEO, &tv)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // NewHandle returns a netlink handle on the network namespace
 // specified by ns. If ns=netns.None(), current network namespace
 // will be assumed

handle_test.go

@@ -8,7 +8,10 @@ import (
 	"net"
 	"sync"
 	"sync/atomic"
+	"syscall"
 	"testing"
+	"time"
+	"unsafe"
 
 	"github.com/vishvananda/netlink/nl"
 	"github.com/vishvananda/netns"
@@ -107,6 +110,48 @@ func TestHandleCreateNetns(t *testing.T) {
 	}
 }
 
+func TestHandleTimeout(t *testing.T) {
+	h, err := NewHandle()
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer h.Delete()
+
+	for _, sh := range h.sockets {
+		verifySockTimeVal(t, sh.Socket.GetFd(), syscall.Timeval{Sec: 0, Usec: 0})
+	}
+
+	h.SetSocketTimeout(2*time.Second + 8*time.Millisecond)
+
+	for _, sh := range h.sockets {
+		verifySockTimeVal(t, sh.Socket.GetFd(), syscall.Timeval{Sec: 2, Usec: 8000})
+	}
+}
+
+func verifySockTimeVal(t *testing.T, fd int, tv syscall.Timeval) {
+	var (
+		tr syscall.Timeval
+		v  = uint32(0x10)
+	)
+	_, _, errno := syscall.Syscall6(syscall.SYS_GETSOCKOPT, uintptr(fd), syscall.SOL_SOCKET, syscall.SO_SNDTIMEO, uintptr(unsafe.Pointer(&tr)), uintptr(unsafe.Pointer(&v)), 0)
+	if errno != 0 {
+		t.Fatal(errno)
+	}
+
+	if tr.Sec != tv.Sec || tr.Usec != tv.Usec {
+		t.Fatalf("Unexpected timeout value read: %v. Expected: %v", tr, tv)
+	}
+
+	_, _, errno = syscall.Syscall6(syscall.SYS_GETSOCKOPT, uintptr(fd), syscall.SOL_SOCKET, syscall.SO_RCVTIMEO, uintptr(unsafe.Pointer(&tr)), uintptr(unsafe.Pointer(&v)), 0)
+	if errno != 0 {
+		t.Fatal(errno)
+	}
+
+	if tr.Sec != tv.Sec || tr.Usec != tv.Usec {
+		t.Fatalf("Unexpected timeout value read: %v. Expected: %v", tr, tv)
+	}
+}
+
 var (
 	iter      = 10
 	numThread = uint32(4)