diff --git a/base/inet.hh b/base/inet.hh
index 86a04aae4..b20c90beb 100644
--- a/base/inet.hh
+++ b/base/inet.hh
@@ -53,15 +53,30 @@
 
 std::string eaddr_string(const uint8_t a[6]);
 
+struct EthHdr;
+struct IpHdr;
+struct TcpHdr;
+struct UdpHdr;
+
 struct EthHdr : protected eth_hdr
 {
     uint16_t type() const { return ntohs(eth_type); }
-    const uint8_t *payload() const { return (const uint8_t *)this + sizeof(*this); }
-    uint8_t *payload() { return (uint8_t *)this + sizeof(*this); }
+
+    const IpHdr *ip() const
+    { return type() == ETH_TYPE_IP ? (const IpHdr *)payload() : 0; }
+
+    IpHdr *ip()
+    { return type() == ETH_TYPE_IP ? (IpHdr *)payload() : 0; }
 
     bool unicast() { return eth_dst.data[0] == 0x00; }
     bool multicast() { return eth_dst.data[0] == 0x01; }
     bool broadcast() { return eth_dst.data[0] == 0xff; }
+
+    int size() const { return sizeof(EthHdr); }
+    const uint8_t *bytes() const { return (const uint8_t *)this; }
+    const uint8_t *payload() const { return bytes() + size(); }
+    uint8_t *bytes() { return (uint8_t *)this; }
+    uint8_t *payload() { return bytes() + size(); }
 };
 
 struct IpHdr : protected ip_hdr
@@ -83,8 +98,23 @@ struct IpHdr : protected ip_hdr
 
     uint16_t ip_cksum() const;
     uint16_t tu_cksum() const;
-    const uint8_t  *payload() const { return (const uint8_t *)this + hlen(); }
-    uint8_t  *payload() { return (uint8_t *)this + hlen(); }
+
+    const TcpHdr *tcp() const
+    { return proto() == IP_PROTO_TCP ? (const TcpHdr *)payload() : 0; }
+    const UdpHdr *udp() const
+    { return proto() == IP_PROTO_UDP ? (const UdpHdr *)payload() : 0; }
+
+    TcpHdr *tcp()
+    { return proto() == IP_PROTO_TCP ? (TcpHdr *)payload() : 0; }
+    UdpHdr *udp()
+    { return proto() == IP_PROTO_UDP ? (UdpHdr *)payload() : 0; }
+
+
+    int size() const { return hlen(); }
+    const uint8_t *bytes() const { return (const uint8_t *)this; }
+    const uint8_t *payload() const { return bytes() + size(); }
+    uint8_t *bytes() { return (uint8_t *)this; }
+    uint8_t *payload() { return bytes() + size(); }
 };
 
 struct TcpHdr : protected tcp_hdr
@@ -101,8 +131,11 @@ struct TcpHdr : protected tcp_hdr
 
     void sum(uint16_t sum) { th_sum = htons(sum); }
 
-    const uint8_t *payload() const { return (const uint8_t *)this + off(); }
-    uint8_t *payload() { return (uint8_t *)this + off(); }
+    int size() const { return off(); }
+    const uint8_t *bytes() const { return (const uint8_t *)this; }
+    const uint8_t *payload() const { return bytes() + size(); }
+    uint8_t *bytes() { return (uint8_t *)this; }
+    uint8_t *payload() { return bytes() + size(); }
 };
 
 struct UdpHdr : protected udp_hdr
@@ -114,8 +147,11 @@ struct UdpHdr : protected udp_hdr
 
     void sum(uint16_t sum) { uh_sum = htons(sum); }
 
-    const uint8_t *payload() const { return (const uint8_t *)this + sizeof(*this); }
-    uint8_t *payload() { return (uint8_t *)this + sizeof(*this); }
+    int size() const { return sizeof(UdpHdr); }
+    const uint8_t *bytes() const { return (const uint8_t *)this; }
+    const uint8_t *payload() const { return bytes() + size(); }
+    uint8_t *bytes() { return (uint8_t *)this; }
+    uint8_t *payload() { return bytes() + size(); }
 };
 
 #endif // __BASE_INET_HH__
diff --git a/dev/etherpkt.cc b/dev/etherpkt.cc
index 292fe7faf..273b8ee64 100644
--- a/dev/etherpkt.cc
+++ b/dev/etherpkt.cc
@@ -33,29 +33,6 @@
 
 using namespace std;
 
-void
-PacketData::doext()
-{
-    _eth = 0;
-    _ip = 0;
-    _tcp = 0;
-    _udp = 0;
-
-    if (!data)
-        return;
-
-    _eth = data;
-    if (eth()->type() == ETH_TYPE_IP) {
-        _ip = eth()->payload();
-
-        if (ip()->proto() == IP_PROTO_TCP)
-            _tcp = ip()->payload();
-
-        if (ip()->proto() == IP_PROTO_UDP)
-            _udp = ip()->payload();
-    }
-}
-
 void
 PacketData::serialize(ostream &os)
 {
diff --git a/dev/etherpkt.hh b/dev/etherpkt.hh
index 53612b830..9c5f00491 100644
--- a/dev/etherpkt.hh
+++ b/dev/etherpkt.hh
@@ -51,30 +51,22 @@ class PacketData : public RefCounted
     uint8_t *data;
     int length;
 
-  protected:
-    uint8_t *_eth;
-    uint8_t *_ip;
-    uint8_t *_tcp;
-    uint8_t *_udp;
-
-    void doext();
-    void ext()
-    {
-        if (_eth != data)
-            doext();
-    }
-
   public:
-    PacketData() : data(NULL), length(0) { doext(); }
+    PacketData() : data(NULL), length(0) { }
     PacketData(std::auto_ptr<uint8_t> d, int l)
-        : data(d.release()), length(l) { doext(); }
+        : data(d.release()), length(l) { }
     ~PacketData() { if (data) delete [] data; }
 
   public:
-    EthHdr *eth() { ext(); return (EthHdr *)_eth; }
-    IpHdr *ip() { ext(); return (IpHdr *)_ip; }
-    TcpHdr *tcp() { ext(); return (TcpHdr *)_tcp; }
-    UdpHdr *udp() { ext(); return (UdpHdr *)_udp; }
+    const EthHdr *eth() const { return (const EthHdr *)data; }
+    const IpHdr *ip() const {const EthHdr *h = eth(); return h ? h->ip() : 0;}
+    const TcpHdr *tcp() const {const IpHdr *h = ip(); return h ? h->tcp() : 0;}
+    const UdpHdr *udp() const {const IpHdr *h = ip(); return h ? h->udp() : 0;}
+
+    EthHdr *eth() { return (EthHdr *)data; }
+    IpHdr *ip()   { EthHdr *h = eth(); return h ? h->ip() : 0; }
+    TcpHdr *tcp() { IpHdr *h = ip(); return h ? h->tcp() : 0; }
+    UdpHdr *udp() { IpHdr *h = ip(); return h ? h->udp() : 0; }
 
   public:
     void serialize(std::ostream &os);