a bit more cleaning of the network header wrappers.

base/inet.hh:
    add functions to the various headers to grab the most common
    encapsulated protocols.  This could easily get out of hand, but
    we're just worrying about tcp, udp, and ip for now.

    add common functions size(), bytes(), and payload() to all wrappers.
    size() gets the header size
    bytes() returns a uint8_t * to the beginning of the header
    payload() returns a uint8_t * to the beginning of the payload.
dev/etherpkt.cc:
dev/etherpkt.hh:
    don't cache pointers to headers.  It's probably not worth the
    hassle.

--HG--
extra : convert_revision : ba9df85ac019b8a48233042dde79fb9da9546410

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__

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)
 {

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);