Modules/IPStack/ipv4.c

   1 /*
   2  * Acess2 IP Stack
   3  * - IPv4 Protcol Handling
   4  */
   5 #include "ipstack.h"
   6 #include "link.h"
   7 #include "ipv4.h"
   8
   9 // === PROTOTYPES ===
  10  int    IPv4_Initialise();
  11 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  12 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  13 Uint32  IPv4_Netmask(int FixedBits);
  14
  15 // === GLOBALS ===
  16 tIPCallback     gaIPv4_Callbacks[256];
  17
  18 // === CODE ===
  19 /**
  20  * \fn int IPv4_Initialise()
  21  */
  22 int IPv4_Initialise()
  23 {
  24         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  25         return 1;
  26 }
  27
  28 /**
  29  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
  30  * \brief Process an IPv4 Packet
  31  */
  32 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  33 {
  34         tIPv4Header     *hdr = Buffer;
  35         tInterface      *iface;
  36         char    *data;
  37          int    dataLength;
  38         if(Length < sizeof(tIPv4Header))        return;
  39
  40         // Check that the version IS IPv4
  41         if(hdr->Version != 4)   return;
  42
  43         // Check Header checksum
  44         //TODO
  45
  46         // Check Packet length
  47         if(hdr->TotalLength > Length)   return;
  48
  49         // Get Interface (allowing broadcasts)
  50         iface = IPv4_GetInterface(Adapter, hdr->Source, 1);
  51         if(!iface)      return; // Not for us? Well, let's ignore it
  52
  53         // Defragment
  54         //TODO
  55
  56         dataLength = hdr->TotalLength - sizeof(tIPv4Header);
  57         data = &hdr->Options[0];
  58
  59         // Send it on
  60         gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
  61 }
  62
  63 /**
  64  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
  65  * \brief Searches an adapter for a matching address
  66  */
  67 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
  68 {
  69         tInterface      *iface = NULL;
  70         Uint32  netmask;
  71
  72         for( iface = Adapter->Interfaces; iface; iface = iface->Next)
  73         {
  74                 if( iface->Type != 4 )  continue;
  75                 if( IP4_EQU(Address, iface->IP4.Address) )
  76                         return iface;
  77
  78                 if( !Broadcast )        continue;
  79
  80                 // Check for broadcast
  81                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
  82                 if( (Address.L & netmask) == (iface->IP4.Address.L & netmask)
  83                  && (Address.L & ~netmask) == (0xFFFFFFFF & ~netmask) )
  84                         return iface;
  85         }
  86         return NULL;
  87 }
  88
  89 /**
  90  * \brief Convert a network prefix to a netmask
  91  *
  92  * For example /24 will become 255.255.255.0
  93  */
  94 Uint32 IPv4_Netmask(int FixedBits)
  95 {
  96         Uint32  ret = 0xFFFFFFFF;
  97         ret >>= (32-FixedBits);
  98         ret <<= (32-FixedBits);
  99         return ret;
 100 }