From beb488f6fad992aaa8b5724377d6b500b83f7618 Mon Sep 17 00:00:00 2001
From: Michael Stapelberg <stapelberg@google.com>
Date: Thu, 28 Jun 2018 20:05:27 +0200
Subject: [PATCH] implement expr.Payload unmarshaling

---
 expr/payload.go | 21 ++++++++++++++++++---
 nftables.go     |  2 ++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/expr/payload.go b/expr/payload.go
index d04b9fa..11727c3 100644
--- a/expr/payload.go
+++ b/expr/payload.go
@@ -15,8 +15,6 @@
 package expr
 
 import (
-	"fmt"
-
 	"github.com/google/nftables/binaryutil"
 	"github.com/mdlayher/netlink"
 	"golang.org/x/sys/unix"
@@ -55,5 +53,22 @@ func (e *Payload) marshal() ([]byte, error) {
 }
 
 func (e *Payload) unmarshal(data []byte) error {
-	return fmt.Errorf("not yet implemented")
+	attrs, err := netlink.UnmarshalAttributes(data)
+	if err != nil {
+		return err
+	}
+	for _, attr := range attrs {
+		switch attr.Type {
+		case unix.NFTA_PAYLOAD_DREG:
+			e.DestRegister = binaryutil.BigEndian.Uint32(attr.Data)
+		case unix.NFTA_PAYLOAD_BASE:
+			e.Base = PayloadBase(binaryutil.BigEndian.Uint32(attr.Data))
+		case unix.NFTA_PAYLOAD_OFFSET:
+			e.Offset = binaryutil.BigEndian.Uint32(attr.Data)
+		case unix.NFTA_PAYLOAD_LEN:
+			e.Len = binaryutil.BigEndian.Uint32(attr.Data)
+		}
+	}
+
+	return nil
 }
diff --git a/nftables.go b/nftables.go
index b2d07a2..d6f54a9 100644
--- a/nftables.go
+++ b/nftables.go
@@ -213,6 +213,8 @@ func exprsFromMsg(b []byte) ([]expr.Any, error) {
 			e = &expr.Cmp{}
 		case "counter":
 			e = &expr.Counter{}
+		case "payload":
+			e = &expr.Payload{}
 		}
 		if e == nil {
 			// TODO: introduce an opaque expression type so that users know