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 #define DEFAULT_TTL     32
  10
  11 // === IMPORTS ===
  12 extern tInterface       *gIP_Interfaces;
  13 extern void     ICMP_Initialise();
  14 extern  int     ICMP_Ping(tInterface *Interface, tIPv4 Addr);
  15 extern void     UDP_Initialise();
  16 extern tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address);
  17
  18 // === PROTOTYPES ===
  19  int    IPv4_Initialise();
  20  int    IPv4_RegisterCallback(int ID, tIPCallback Callback);
  21 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  22 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  23 Uint32  IPv4_Netmask(int FixedBits);
  24 Uint16  IPv4_Checksum(void *Buf, int Size);
  25  int    IPv4_Ping(tInterface *Iface, tIPv4 Addr);
  26
  27 // === GLOBALS ===
  28 tIPCallback     gaIPv4_Callbacks[256];
  29
  30 // === CODE ===
  31 /**
  32  * \fn int IPv4_Initialise()
  33  */
  34 int IPv4_Initialise()
  35 {
  36         ICMP_Initialise();
  37         UDP_Initialise();
  38         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  39         return 1;
  40 }
  41
  42 /**
  43  * \fn int IPv4_RegisterCallback( int ID, tIPCallback Callback )
  44  * \brief Registers a callback
  45  */
  46 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  47 {
  48         if( ID < 0 || ID > 255 )        return 0;
  49         if( gaIPv4_Callbacks[ID] )      return 0;
  50         gaIPv4_Callbacks[ID] = Callback;
  51         return 1;
  52 }
  53
  54 /**
  55  * \brief Creates and sends an IPv4 Packet
  56  */
  57 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, void *Data)
  58 {
  59         tMacAddr        to = ARP_Resolve4(Iface, Address);
  60          int    bufSize = sizeof(tIPv4Header) + Length;
  61         char    buf[bufSize];
  62         tIPv4Header     *hdr = (void*)buf;
  63
  64         memcpy(&hdr->Options[0], Data, Length);
  65         hdr->Version = 4;
  66         hdr->HeaderLength = htons( sizeof(tIPv4Header) );
  67         hdr->DiffServices = 0;  // TODO: Check
  68         hdr->TotalLength = htons( bufSize );
  69         hdr->Identifcation = htons( ID );       // TODO: Check
  70         hdr->TTL = DEFAULT_TTL;
  71         hdr->Protocol = Protocol;
  72         hdr->HeaderChecksum = 0;        // Will be set later
  73         hdr->Source = Iface->IP4.Address;
  74         hdr->Destination = Address;
  75         hdr->HeaderChecksum = htons( IPv4_Checksum(hdr, sizeof(tIPv4Header)) );
  76
  77         Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, bufSize, buf);
  78         return 1;
  79 }
  80
  81 /**
  82  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
  83  * \brief Process an IPv4 Packet
  84  */
  85 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  86 {
  87         tIPv4Header     *hdr = Buffer;
  88         tInterface      *iface;
  89         Uint8   *data;
  90          int    dataLength;
  91         if(Length < sizeof(tIPv4Header))        return;
  92
  93         //Log("[IPv4 ] Version = %i", hdr->Version);
  94         Log("[IPv4 ] HeaderLength = %i", hdr->HeaderLength);
  95         Log("[IPv4 ] DiffServices = %i", hdr->DiffServices);
  96         //Log("[IPv4 ] TotalLength = %i", ntohs(hdr->TotalLength) );
  97         //Log("[IPv4 ] Identifcation = %i", ntohs(hdr->Identifcation) );
  98         //Log("[IPv4 ] TTL = %i", hdr->TTL );
  99         Log("[IPv4 ] Protocol = %i", hdr->Protocol );
 100         //Log("[IPv4 ] HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
 101         Log("[IPv4 ] Source = %i.%i.%i.%i",
 102                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
 103         Log("[IPv4 ] Destination = %i.%i.%i.%i",
 104                 hdr->Destination.B[0], hdr->Destination.B[1],
 105                 hdr->Destination.B[2], hdr->Destination.B[3] );
 106
 107         // Check that the version IS IPv4
 108         if(hdr->Version != 4) {
 109                 Log("[IPv4 ] hdr->Version(%i) != 4", hdr->Version);
 110                 return;
 111         }
 112
 113         // Check Header checksum
 114         //TODO
 115
 116         // Check Packet length
 117         if( ntohs(hdr->TotalLength) > Length) {
 118                 Log("[IPv4 ] hdr->TotalLength(%i) > Length(%i)", hdr->TotalLength, Length);
 119                 return;
 120         }
 121
 122         // Get Interface (allowing broadcasts)
 123         iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
 124         if(!iface) {
 125                 Log("[IPv4 ] Ignoring Packet (Not for us)");
 126                 return; // Not for us? Well, let's ignore it
 127         }
 128
 129         // Defragment
 130         //TODO
 131
 132         dataLength = hdr->TotalLength - sizeof(tIPv4Header);
 133         data = &hdr->Options[0];
 134
 135         // Send it on
 136         gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
 137 }
 138
 139 /**
 140  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 141  * \brief Searches an adapter for a matching address
 142  */
 143 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 144 {
 145         tInterface      *iface = NULL;
 146         Uint32  netmask;
 147         Uint32  addr, this;
 148
 149         addr = ntohl( Address.L );
 150
 151         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 152         {
 153                 if( iface->Adapter != Adapter ) continue;
 154                 if( iface->Type != 4 )  continue;
 155                 if( IP4_EQU(Address, iface->IP4.Address) )
 156                         return iface;
 157
 158                 if( !Broadcast )        continue;
 159
 160                 this = ntohl( iface->IP4.Address.L );
 161
 162                 // Check for broadcast
 163                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
 164
 165                 //Log("netmask = 0x%08x", netmask);
 166                 //Log("addr = 0x%08x", addr);
 167                 //Log("this = 0x%08x", this);
 168                 //Log("%08x == %08x && %08x == %08x",
 169                 //      (addr & netmask), (this & netmask),
 170                 //      (addr & ~netmask), (0xFFFFFFFF & ~netmask)
 171                 //      );
 172                 if( (addr & netmask) == (this & netmask)
 173                  && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 174                         return iface;
 175         }
 176         return NULL;
 177 }
 178
 179 /**
 180  * \brief Convert a network prefix to a netmask
 181  *
 182  * For example /24 will become 255.255.255.0
 183  */
 184 Uint32 IPv4_Netmask(int FixedBits)
 185 {
 186         Uint32  ret = 0xFFFFFFFF;
 187         ret >>= (32-FixedBits);
 188         ret <<= (32-FixedBits);
 189         // Returs a little endian netmask
 190         return ret;
 191 }
 192
 193 /**
 194  * \brief Calculate the IPv4 Checksum
 195  */
 196 Uint16 IPv4_Checksum(void *Buf, int Size)
 197 {
 198         Uint16  sum = 0;
 199         Uint16  *arr = Buf;
 200          int    i;
 201
 202         Size = (Size + 1) >> 1;
 203         for(i = 0; i < Size; i++ )
 204         {
 205                 if((int)sum + arr[i] > 0xFFFF)
 206                         sum ++; // Simulate 1's complement
 207                 sum += arr[i];
 208         }
 209         return ~sum;
 210 }
 211
 212 /**
 213  * \brief Sends an ICMP Echo and waits for a reply
 214  */
 215 int IPv4_Ping(tInterface *Iface, tIPv4 Addr)
 216 {
 217         return ICMP_Ping(Iface, Addr);
 218 }