internal/netlink: make full response available

The previous API makes it impossible to retrieve remaining messages in the current iteration.

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

internal/netlink/netlink.go

@@ -143,8 +143,45 @@ type Complete struct{}
 // Error returns a hardcoded string that should never be displayed to the user.
 func (Complete) Error() string { return "returning from roundtrip" }
 
+// HandlerFunc handles [syscall.NetlinkMessage] and returns a non-nil error to
+// discontinue the receiving of more messages.
+type HandlerFunc func(resp []syscall.NetlinkMessage) error
+
+// receive receives from a socket with specified flags until a non-nil error is
+// returned by f. An error of type [Complete] is returned as nil.
+func (c *conn) receive(f HandlerFunc, flags int) error {
+	for {
+		buf := c.buf
+		if n, _, err := syscall.Recvfrom(c.fd, buf, flags); err != nil {
+			return os.NewSyscallError("recvfrom", err)
+		} else if n < syscall.NLMSG_HDRLEN {
+			return syscall.EBADE
+		} else {
+			buf = buf[:n]
+		}
+
+		resp, err := syscall.ParseNetlinkMessage(buf)
+		if err != nil {
+			return err
+		}
+
+		for i := range resp {
+			header := &resp[i].Header
+			if header.Seq != c.seq || header.Pid != getpid() {
+				return &InconsistentError{*header, c.seq, getpid()}
+			}
+		}
+		if err = f(resp); err != nil {
+			if err == (Complete{}) {
+				return nil
+			}
+			return err
+		}
+	}
+}
+
 // Roundtrip sends the pending message and handles the reply.
-func (c *conn) Roundtrip(f func(msg *syscall.NetlinkMessage) error) error {
+func (c *conn) Roundtrip(f HandlerFunc) error {
 	if c.buf == nil {
 		return syscall.EINVAL
 	}
@@ -158,38 +195,3 @@ func (c *conn) Roundtrip(f func(msg *syscall.NetlinkMessage) error) error {
 
 	return c.receive(f, 0)
 }
-
-// receive receives from a socket with specified flags until a non-nil error is
-// returned by f. An error of type [Complete] is returned as nil.
-func (c *conn) receive(
-	f func(msg *syscall.NetlinkMessage) error,
-	flags int,
-) error {
-	for {
-		buf := c.buf
-		if n, _, err := syscall.Recvfrom(c.fd, buf, flags); err != nil {
-			return os.NewSyscallError("recvfrom", err)
-		} else if n < syscall.NLMSG_HDRLEN {
-			return syscall.EBADE
-		} else {
-			buf = buf[:n]
-		}
-
-		msgs, err := syscall.ParseNetlinkMessage(buf)
-		if err != nil {
-			return err
-		}
-
-		for _, msg := range msgs {
-			if msg.Header.Seq != c.seq || msg.Header.Pid != getpid() {
-				return &InconsistentError{msg.Header, c.seq, getpid()}
-			}
-			if err = f(&msg); err != nil {
-				if err == (Complete{}) {
-					return nil
-				}
-				return err
-			}
-		}
-	}
-}

internal/netlink/rtnl.go

@@ -18,23 +18,23 @@ func DialRoute() (*RouteConn, error) {
 }
 
 // rtnlConsume consumes a message from rtnetlink.
-func rtnlConsume(msg *syscall.NetlinkMessage) error {
-	switch msg.Header.Type {
-	case syscall.NLMSG_DONE:
-		return Complete{}
+func rtnlConsume(resp []syscall.NetlinkMessage) error {
+	for i := range resp {
+		switch resp[i].Header.Type {
+		case syscall.NLMSG_DONE:
+			return Complete{}
 
-	case syscall.NLMSG_ERROR:
-		if e := As[syscall.NlMsgerr](msg.Data); e != nil {
-			if e.Error == 0 {
-				return Complete{}
+		case syscall.NLMSG_ERROR:
+			if e := As[syscall.NlMsgerr](resp[i].Data); e != nil {
+				if e.Error == 0 {
+					return Complete{}
+				}
+				return syscall.Errno(-e.Error)
 			}
-			return syscall.Errno(-e.Error)
+			return syscall.EBADE
 		}
-		return syscall.EBADE
-
-	default:
-		return nil
 	}
+	return nil
 }
 
 // InAddr is equivalent to struct in_addr.