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 // === IMPORTS ===
  10 extern tInterface       *gIP_Interfaces;
  11
  12 // === PROTOTYPES ===
  13  int    IPv4_Initialise();
  14 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  15 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  16 Uint32  IPv4_Netmask(int FixedBits);
  17
  18 // === GLOBALS ===
  19 tIPCallback     gaIPv4_Callbacks[256];
  20
  21 // === CODE ===
  22 /**
  23  * \fn int IPv4_Initialise()
  24  */
  25 int IPv4_Initialise()
  26 {
  27         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  28         return 1;
  29 }
  30
  31 /**
  32  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
  33  * \brief Process an IPv4 Packet
  34  */
  35 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  36 {
  37         tIPv4Header     *hdr = Buffer;
  38         tInterface      *iface;
  39         Uint8   *data;
  40          int    dataLength;
  41         if(Length < sizeof(tIPv4Header))        return;
  42
  43         // Check that the version IS IPv4
  44         if(hdr->Version != 4)   return;
  45
  46         // Check Header checksum
  47         //TODO
  48
  49         // Check Packet length
  50         if(hdr->TotalLength > Length)   return;
  51
  52         // Get Interface (allowing broadcasts)
  53         iface = IPv4_GetInterface(Adapter, hdr->Source, 1);
  54         if(!iface)      return; // Not for us? Well, let's ignore it
  55
  56         // Defragment
  57         //TODO
  58
  59         dataLength = hdr->TotalLength - sizeof(tIPv4Header);
  60         data = &hdr->Options[0];
  61
  62         // Send it on
  63         gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
  64 }
  65
  66 /**
  67  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
  68  * \brief Searches an adapter for a matching address
  69  */
  70 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
  71 {
  72         tInterface      *iface = NULL;
  73         Uint32  netmask;
  74
  75         for( iface = gIP_Interfaces; iface; iface = iface->Next)
  76         {
  77                 if( iface->Adapter != Adapter ) continue;
  78                 if( iface->Type != 4 )  continue;
  79                 if( IP4_EQU(Address, iface->IP4.Address) )
  80                         return iface;
  81
  82                 if( !Broadcast )        continue;
  83
  84                 // Check for broadcast
  85                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
  86                 if( (Address.L & netmask) == (iface->IP4.Address.L & netmask)
  87                  && (Address.L & ~netmask) == (0xFFFFFFFF & ~netmask) )
  88                         return iface;
  89         }
  90         return NULL;
  91 }
  92
  93 /**
  94  * \brief Convert a network prefix to a netmask
  95  *
  96  * For example /24 will become 255.255.255.0
  97  */
  98 Uint32 IPv4_Netmask(int FixedBits)
  99 {
 100         Uint32  ret = 0xFFFFFFFF;
 101         ret >>= (32-FixedBits);
 102         ret <<= (32-FixedBits);
 103         return ret;
 104 }