diff --git a/Makefile b/Makefile
index ca9c3f25..9a1786ff 100644
--- a/Makefile
+++ b/Makefile
@@ -19,6 +19,7 @@ GOFILES=\
 	nsec3.go \
 	qnamestring.go\
 	server.go \
+	rawmsg.go \
 	tsig.go\
 	types.go\
 	xfr.go\
diff --git a/msg.go b/msg.go
index d5b288cf..a7f6cf52 100644
--- a/msg.go
+++ b/msg.go
@@ -47,7 +47,7 @@ var (
 	ErrXfrSoa    os.Error = &Error{Error: "no SOA seen"}
 	ErrHandle    os.Error = &Error{Error: "handle is nil"}
 	ErrChan      os.Error = &Error{Error: "channel is nil"}
-        ErrName      os.Error = &Error{Error: "type not found for name"}
+	ErrName      os.Error = &Error{Error: "type not found for name"}
 )
 
 // A manually-unpacked version of (id, bits).
@@ -360,47 +360,47 @@ func packStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok bool)
 			}
 		case reflect.Struct:
 			off, ok = packStructValue(fv, msg, off)
-                case reflect.Uint8:
-                        if off+1 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow packing uint8")
-                                return len(msg), false
-                        }
-                        msg[off] = byte(fv.Uint())
-                        off++
-                case reflect.Uint16:
-                        if off+2 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow packing uint16")
-                                return len(msg), false
-                        }
-                        i := fv.Uint()
-                        msg[off] = byte(i >> 8)
-                        msg[off+1] = byte(i)
-                        off += 2
-                case reflect.Uint32:
-                        if off+4 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow packing uint32")
-                                return len(msg), false
-                        }
-                        i := fv.Uint()
-                        msg[off] = byte(i >> 24)
-                        msg[off+1] = byte(i >> 16)
-                        msg[off+2] = byte(i >> 8)
-                        msg[off+3] = byte(i)
-                        off += 4
-                case reflect.Uint64:
-                        // Only used in TSIG, where it stops at 48 bits, so we discard the upper 16
-                        if off+6 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow packing uint64")
-                                return len(msg), false
-                        }
-                        i := fv.Uint()
-                        msg[off] = byte(i >> 40)
-                        msg[off+1] = byte(i >> 32)
-                        msg[off+2] = byte(i >> 24)
-                        msg[off+3] = byte(i >> 16)
-                        msg[off+4] = byte(i >> 8)
-                        msg[off+5] = byte(i)
-                        off += 6
+		case reflect.Uint8:
+			if off+1 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow packing uint8")
+				return len(msg), false
+			}
+			msg[off] = byte(fv.Uint())
+			off++
+		case reflect.Uint16:
+			if off+2 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow packing uint16")
+				return len(msg), false
+			}
+			i := fv.Uint()
+			msg[off] = byte(i >> 8)
+			msg[off+1] = byte(i)
+			off += 2
+		case reflect.Uint32:
+			if off+4 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow packing uint32")
+				return len(msg), false
+			}
+			i := fv.Uint()
+			msg[off] = byte(i >> 24)
+			msg[off+1] = byte(i >> 16)
+			msg[off+2] = byte(i >> 8)
+			msg[off+3] = byte(i)
+			off += 4
+		case reflect.Uint64:
+			// Only used in TSIG, where it stops at 48 bits, so we discard the upper 16
+			if off+6 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow packing uint64")
+				return len(msg), false
+			}
+			i := fv.Uint()
+			msg[off] = byte(i >> 40)
+			msg[off+1] = byte(i >> 32)
+			msg[off+2] = byte(i >> 24)
+			msg[off+3] = byte(i >> 16)
+			msg[off+4] = byte(i >> 8)
+			msg[off+5] = byte(i)
+			off += 6
 		case reflect.String:
 			// There are multiple string encodings.
 			// The tag distinguishes ordinary strings from domain names.
@@ -591,41 +591,41 @@ func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, ok boo
 			}
 		case reflect.Struct:
 			off, ok = unpackStructValue(fv, msg, off)
-                case reflect.Uint8:
-                        if off+1 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint8")
-                                return len(msg), false
-                        }
-                        i := uint8(msg[off])
-                        fv.SetUint(uint64(i))
-                        off++
-                case reflect.Uint16:
-                        var i uint16
-                        if off+2 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint16")
-                                return len(msg), false
-                        }
-                        i, off = unpackUint16(msg, off)
-                        fv.SetUint(uint64(i))
-                case reflect.Uint32:
-                        if off+4 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint32")
-                                return len(msg), false
-                        }
-                        i := uint32(msg[off])<<24 | uint32(msg[off+1])<<16 | uint32(msg[off+2])<<8 | uint32(msg[off+3])
-                        fv.SetUint(uint64(i))
-                        off += 4
-                case reflect.Uint64:
-                        // This is *only* used in TSIG where the last 48 bits are occupied
-                        // So for now, assume a uint48 (6 bytes)
-                        if off+6 > len(msg) {
-                                //fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint64")
-                                return len(msg), false
-                        }
-                        i := uint64(msg[off])<<40 | uint64(msg[off+1])<<32 | uint64(msg[off+2])<<24 | uint64(msg[off+3])<<16 |
-                                uint64(msg[off+4])<<8 | uint64(msg[off+5])
-                        fv.SetUint(uint64(i))
-                        off += 6
+		case reflect.Uint8:
+			if off+1 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint8")
+				return len(msg), false
+			}
+			i := uint8(msg[off])
+			fv.SetUint(uint64(i))
+			off++
+		case reflect.Uint16:
+			var i uint16
+			if off+2 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint16")
+				return len(msg), false
+			}
+			i, off = unpackUint16(msg, off)
+			fv.SetUint(uint64(i))
+		case reflect.Uint32:
+			if off+4 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint32")
+				return len(msg), false
+			}
+			i := uint32(msg[off])<<24 | uint32(msg[off+1])<<16 | uint32(msg[off+2])<<8 | uint32(msg[off+3])
+			fv.SetUint(uint64(i))
+			off += 4
+		case reflect.Uint64:
+			// This is *only* used in TSIG where the last 48 bits are occupied
+			// So for now, assume a uint48 (6 bytes)
+			if off+6 > len(msg) {
+				//fmt.Fprintf(os.Stderr, "dns: overflow unpacking uint64")
+				return len(msg), false
+			}
+			i := uint64(msg[off])<<40 | uint64(msg[off+1])<<32 | uint64(msg[off+2])<<24 | uint64(msg[off+3])<<16 |
+				uint64(msg[off+4])<<8 | uint64(msg[off+5])
+			fv.SetUint(uint64(i))
+			off += 6
 		case reflect.String:
 			var s string
 			switch f.Tag {
@@ -829,11 +829,9 @@ func packRR(rr RR, msg []byte, off int) (off2 int, ok bool) {
 	if !ok {
 		return len(msg), false
 	}
-
-	// TODO make this quicker
-	// pack a third time; redo header with correct data length
-	rr.Header().Rdlength = uint16(off2 - off1)
-	packStruct(rr.Header(), msg, off)
+	if !RawSetRdlength(msg, uint16(off2-off1)) {
+                return len(msg), false
+        }
 	return off2, true
 }
 
diff --git a/rawmsg.go b/rawmsg.go
new file mode 100644
index 00000000..f1b53440
--- /dev/null
+++ b/rawmsg.go
@@ -0,0 +1,25 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dns
+
+/* Function defined in this subpackage work on []byte and but still
+ * provide some higher level functions
+ */
+
+
+// SetRdlength sets the length of the length of the rdata
+// directly at the correct position in the buffer buf.
+// If buf does not look like a DNS message false is returned,
+// otherwise true.
+func RawSetRdlength(buf []byte, i uint16) bool {
+        var off int
+        var ok bool
+	if _, off, ok = unpackDomainName(buf, 0); !ok {
+		return false
+	}
+        // off + type(2) + class(2) + ttl(4) -> rdlength
+        buf[off+2+2+4], buf[off+2+2+4+1] = packUint16(i)
+        return true
+}