internal/netlink: switch to recvmsg/sendmsg

These are more flexible than recvfrom/sendto.

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

internal/netlink/netlink.go

@@ -101,13 +101,13 @@ func (c *Conn) Close() error {
 	return c.f.Close()
 }
 
-// Recvfrom wraps recv(2) with nonblocking behaviour via the runtime network poller.
+// Recvmsg wraps recv(2) with nonblocking behaviour via the runtime network poller.
 //
-// The returned slice is valid until the next call to Recvfrom.
-func (c *Conn) Recvfrom(
+// The returned slice is valid until the next call to Recvmsg.
+func (c *Conn) Recvmsg(
 	ctx context.Context,
 	flags int,
-) (data []byte, from syscall.Sockaddr, err error) {
+) (data []byte, recvflags int, from syscall.Sockaddr, err error) {
 	if err = c.f.SetReadDeadline(time.Time{}); err != nil {
 		return
 	}
@@ -117,7 +117,7 @@ func (c *Conn) Recvfrom(
 	done := make(chan error, 1)
 	go func() {
 		rcErr := c.raw.Read(func(fd uintptr) (done bool) {
-			n, from, err = syscall.Recvfrom(int(fd), data, flags)
+			n, _, recvflags, from, err = syscall.Recvmsg(int(fd), data, nil, flags)
 			return err != syscall.EWOULDBLOCK
 		})
 		if n >= 0 {
@@ -129,7 +129,7 @@ func (c *Conn) Recvfrom(
 	select {
 	case rcErr := <-done:
 		if err != nil {
-			err = os.NewSyscallError("recvfrom", err)
+			err = os.NewSyscallError("recvmsg", err)
 		} else {
 			err = rcErr
 		}
@@ -147,12 +147,12 @@ func (c *Conn) Recvfrom(
 	}
 }
 
-// Sendto wraps send(2) with nonblocking behaviour via the runtime network poller.
-func (c *Conn) Sendto(
+// Sendmsg wraps send(2) with nonblocking behaviour via the runtime network poller.
+func (c *Conn) Sendmsg(
 	ctx context.Context,
 	p []byte,
-	flags int,
 	to syscall.Sockaddr,
+	flags int,
 ) (err error) {
 	if err = c.f.SetWriteDeadline(time.Time{}); err != nil {
 		return
@@ -161,7 +161,7 @@ func (c *Conn) Sendto(
 	done := make(chan error, 1)
 	go func() {
 		done <- c.raw.Write(func(fd uintptr) (done bool) {
-			err = syscall.Sendto(int(fd), p, flags, to)
+			err = syscall.Sendmsg(int(fd), p, nil, to, flags)
 			return err != syscall.EWOULDBLOCK
 		})
 	}()
@@ -169,7 +169,7 @@ func (c *Conn) Sendto(
 	select {
 	case rcErr := <-done:
 		if err != nil {
-			err = os.NewSyscallError("sendto", err)
+			err = os.NewSyscallError("sendmsg", err)
 		} else {
 			err = rcErr
 		}
@@ -278,7 +278,7 @@ type HandlerFunc func(resp []syscall.NetlinkMessage) error
 func (c *Conn) receive(ctx context.Context, f HandlerFunc, flags int) error {
 	for {
 		var resp []syscall.NetlinkMessage
-		if data, _, err := c.Recvfrom(ctx, flags); err != nil {
+		if data, _, _, err := c.Recvmsg(ctx, flags); err != nil {
 			return err
 		} else if len(data) < syscall.NLMSG_HDRLEN {
 			return syscall.EBADE
@@ -302,9 +302,9 @@ func (c *Conn) Roundtrip(ctx context.Context, f HandlerFunc) error {
 	}
 	defer func() { c.seq++ }()
 
-	if err := c.Sendto(ctx, c.pending(), 0, &syscall.SockaddrNetlink{
+	if err := c.Sendmsg(ctx, c.pending(), &syscall.SockaddrNetlink{
 		Family: syscall.AF_NETLINK,
-	}); err != nil {
+	}, 0); err != nil {
 		return err
 	}
 

internal/uevent/uevent.go

@@ -82,7 +82,7 @@ func (c *Conn) Consume(ctx context.Context, events chan<- *Message) error {
 	defer c.exitExcl()
 
 	for {
-		data, from, err := c.conn.Recvfrom(ctx, 0)
+		data, _, from, err := c.conn.Recvmsg(ctx, 0)
 		if err != nil {
 			return err
 		}