internal/netlink: optional check header as reply

Not every received message is a reply.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/netlink/netlink.go

@@ -232,6 +232,14 @@ func (e *InconsistentError) Error() string {
 	return s
 }
 
+// checkReply checks the message header of a reply from the kernel.
+func (c *conn) checkReply(header *syscall.NlMsghdr) error {
+	if header.Seq != c.seq || header.Pid != c.port {
+		return &InconsistentError{*header, c.seq, c.port}
+	}
+	return nil
+}
+
 // pending returns the valid slice of buf and initialises pos.
 func (c *conn) pending() []byte {
 	buf := c.buf[:c.pos]
@@ -275,12 +283,6 @@ func (c *conn) receive(ctx context.Context, f HandlerFunc, flags int) error {
 			return err
 		}
 
-		for i := range resp {
-			header := &resp[i].Header
-			if header.Seq != c.seq || header.Pid != c.port {
-				return &InconsistentError{*header, c.seq, c.port}
-			}
-		}
 		if err = f(resp); err != nil {
 			if err == (Complete{}) {
 				return nil

internal/netlink/rtnl.go

@@ -19,8 +19,12 @@ func DialRoute() (*RouteConn, error) {
 }
 
 // rtnlConsume consumes a message from rtnetlink.
-func rtnlConsume(resp []syscall.NetlinkMessage) error {
+func (c *conn) rtnlConsume(resp []syscall.NetlinkMessage) error {
 	for i := range resp {
+		if err := c.checkReply(&resp[i].Header); err != nil {
+			return err
+		}
+
 		switch resp[i].Header.Type {
 		case syscall.NLMSG_DONE:
 			return Complete{}
@@ -81,7 +85,7 @@ func (c *RouteConn) SendIfAddrmsg(
 	if !c.writeIfAddrmsg(typ, flags, msg, attrs...) {
 		return syscall.ENOMEM
 	}
-	return c.Roundtrip(ctx, rtnlConsume)
+	return c.Roundtrip(ctx, c.conn.rtnlConsume)
 }
 
 // writeNewaddrLo writes a RTM_NEWADDR message for the loopback address.
@@ -110,7 +114,7 @@ func (c *RouteConn) SendNewaddrLo(ctx context.Context, lo uint32) error {
 	if !c.writeNewaddrLo(lo) {
 		return syscall.ENOMEM
 	}
-	return c.Roundtrip(ctx, rtnlConsume)
+	return c.Roundtrip(ctx, c.conn.rtnlConsume)
 }
 
 // writeIfInfomsg writes an ifinfomsg structure to conn.
@@ -131,5 +135,5 @@ func (c *RouteConn) SendIfInfomsg(
 	if !c.writeIfInfomsg(typ, flags, msg) {
 		return syscall.ENOMEM
 	}
-	return c.Roundtrip(ctx, rtnlConsume)
+	return c.Roundtrip(ctx, c.conn.rtnlConsume)
 }