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 extern void     ICMP_Initialise();
  12 extern void     UDP_Initialise();
  13
  14 // === PROTOTYPES ===
  15  int    IPv4_Initialise();
  16  int    IPv4_RegisterCallback(int ID, tIPCallback Callback);
  17 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  18 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  19 Uint32  IPv4_Netmask(int FixedBits);
  20
  21 // === GLOBALS ===
  22 tIPCallback     gaIPv4_Callbacks[256];
  23
  24 // === CODE ===
  25 /**
  26  * \fn int IPv4_Initialise()
  27  */
  28 int IPv4_Initialise()
  29 {
  30         ICMP_Initialise();
  31         UDP_Initialise();
  32         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  33         return 1;
  34 }
  35
  36 /**
  37  * \fn int IPv4_RegisterCallback( int ID, tIPCallback Callback )
  38  * \brief Registers a callback
  39  */
  40 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  41 {
  42         if( ID < 0 || ID > 255 )        return 0;
  43         if( gaIPv4_Callbacks[ID] )      return 0;
  44         gaIPv4_Callbacks[ID] = Callback;
  45         return 1;
  46 }
  47
  48 /**
  49  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
  50  * \brief Process an IPv4 Packet
  51  */
  52 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  53 {
  54         tIPv4Header     *hdr = Buffer;
  55         tInterface      *iface;
  56         Uint8   *data;
  57          int    dataLength;
  58         if(Length < sizeof(tIPv4Header))        return;
  59
  60         //Log("[IPv4 ] Version = %i", hdr->Version);
  61         Log("[IPv4 ] HeaderLength = %i", hdr->HeaderLength);
  62         Log("[IPv4 ] DiffServices = %i", hdr->DiffServices);
  63         //Log("[IPv4 ] TotalLength = %i", ntohs(hdr->TotalLength) );
  64         //Log("[IPv4 ] Identifcation = %i", ntohs(hdr->Identifcation) );
  65         //Log("[IPv4 ] TTL = %i", hdr->TTL );
  66         Log("[IPv4 ] Protocol = %i", hdr->Protocol );
  67         //Log("[IPv4 ] HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
  68         Log("[IPv4 ] Source = %i.%i.%i.%i",
  69                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
  70         Log("[IPv4 ] Destination = %i.%i.%i.%i",
  71                 hdr->Destination.B[0], hdr->Destination.B[1],
  72                 hdr->Destination.B[2], hdr->Destination.B[3] );
  73
  74         // Check that the version IS IPv4
  75         if(hdr->Version != 4) {
  76                 Log("[IPv4 ] hdr->Version(%i) != 4", hdr->Version);
  77                 return;
  78         }
  79
  80         // Check Header checksum
  81         //TODO
  82
  83         // Check Packet length
  84         if( ntohs(hdr->TotalLength) > Length) {
  85                 Log("[IPv4 ] hdr->TotalLength(%i) > Length(%i)", hdr->TotalLength, Length);
  86                 return;
  87         }
  88
  89         // Get Interface (allowing broadcasts)
  90         iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
  91         if(!iface) {
  92                 Log("[IPv4 ] Ignoring Packet (Not for us)");
  93                 return; // Not for us? Well, let's ignore it
  94         }
  95
  96         // Defragment
  97         //TODO
  98
  99         dataLength = hdr->TotalLength - sizeof(tIPv4Header);
 100         data = &hdr->Options[0];
 101
 102         // Send it on
 103         gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
 104 }
 105
 106 /**
 107  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 108  * \brief Searches an adapter for a matching address
 109  */
 110 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 111 {
 112         tInterface      *iface = NULL;
 113         Uint32  netmask;
 114         Uint32  addr, this;
 115
 116         addr = ntohl( Address.L );
 117
 118         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 119         {
 120                 if( iface->Adapter != Adapter ) continue;
 121                 if( iface->Type != 4 )  continue;
 122                 if( IP4_EQU(Address, iface->IP4.Address) )
 123                         return iface;
 124
 125                 if( !Broadcast )        continue;
 126
 127                 this = ntohl( iface->IP4.Address.L );
 128
 129                 // Check for broadcast
 130                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
 131
 132                 //Log("netmask = 0x%08x", netmask);
 133                 //Log("addr = 0x%08x", addr);
 134                 //Log("this = 0x%08x", this);
 135                 //Log("%08x == %08x && %08x == %08x",
 136                 //      (addr & netmask), (this & netmask),
 137                 //      (addr & ~netmask), (0xFFFFFFFF & ~netmask)
 138                 //      );
 139                 if( (addr & netmask) == (this & netmask)
 140                  && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 141                         return iface;
 142         }
 143         return NULL;
 144 }
 145
 146 /**
 147  * \brief Convert a network prefix to a netmask
 148  *
 149  * For example /24 will become 255.255.255.0
 150  */
 151 Uint32 IPv4_Netmask(int FixedBits)
 152 {
 153         Uint32  ret = 0xFFFFFFFF;
 154         ret >>= (32-FixedBits);
 155         ret <<= (32-FixedBits);
 156         // Returs a little endian netmask
 157         return ret;
 158 }