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 tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address);
  16
  17 // === PROTOTYPES ===
  18  int    IPv4_Initialise();
  19  int    IPv4_RegisterCallback(int ID, tIPCallback Callback);
  20 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  21 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  22 Uint32  IPv4_Netmask(int FixedBits);
  23 Uint16  IPv4_Checksum(void *Buf, int Size);
  24  int    IPv4_Ping(tInterface *Iface, tIPv4 Addr);
  25
  26 // === GLOBALS ===
  27 tIPCallback     gaIPv4_Callbacks[256];
  28
  29 // === CODE ===
  30 /**
  31  * \fn int IPv4_Initialise()
  32  */
  33 int IPv4_Initialise()
  34 {
  35         ICMP_Initialise();
  36         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  37         return 1;
  38 }
  39
  40 /**
  41  * \fn int IPv4_RegisterCallback( int ID, tIPCallback Callback )
  42  * \brief Registers a callback
  43  */
  44 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  45 {
  46         if( ID < 0 || ID > 255 )        return 0;
  47         if( gaIPv4_Callbacks[ID] )      return 0;
  48         gaIPv4_Callbacks[ID] = Callback;
  49         return 1;
  50 }
  51
  52 /**
  53  * \brief Creates and sends an IPv4 Packet
  54  */
  55 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, void *Data)
  56 {
  57         tMacAddr        to = ARP_Resolve4(Iface, Address);
  58          int    bufSize = sizeof(tIPv4Header) + Length;
  59         char    buf[bufSize];
  60         tIPv4Header     *hdr = (void*)buf;
  61
  62         memcpy(&hdr->Options[0], Data, Length);
  63         hdr->Version = 4;
  64         hdr->HeaderLength = sizeof(tIPv4Header)/4;
  65         hdr->DiffServices = 0;  // TODO: Check
  66         hdr->TotalLength = htons( bufSize );
  67         hdr->Identifcation = htons( ID );       // TODO: Check
  68         hdr->TTL = DEFAULT_TTL;
  69         hdr->Protocol = Protocol;
  70         hdr->HeaderChecksum = 0;        // Will be set later
  71         hdr->Source = Iface->IP4.Address;
  72         hdr->Destination = Address;
  73         hdr->HeaderChecksum = htons( IPv4_Checksum(hdr, sizeof(tIPv4Header)) );
  74
  75         Log("[IPv4 ] Sending packet to %i.%i.%i.%i",
  76                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
  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)", ntohs(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 = ntohs(hdr->TotalLength) - sizeof(tIPv4Header);
 133         data = &hdr->Options[0];
 134
 135         // Send it on
 136         if( gaIPv4_Callbacks[hdr->Protocol] )
 137                 gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
 138         else
 139                 Log("[IPv4 ] Unknown Protocol %i", hdr->Protocol);
 140 }
 141
 142 /**
 143  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 144  * \brief Searches an adapter for a matching address
 145  */
 146 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 147 {
 148         tInterface      *iface = NULL;
 149         Uint32  netmask;
 150         Uint32  addr, this;
 151
 152         addr = ntohl( Address.L );
 153
 154         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 155         {
 156                 if( iface->Adapter != Adapter ) continue;
 157                 if( iface->Type != 4 )  continue;
 158                 if( IP4_EQU(Address, iface->IP4.Address) )
 159                         return iface;
 160
 161                 if( !Broadcast )        continue;
 162
 163                 this = ntohl( iface->IP4.Address.L );
 164
 165                 // Check for broadcast
 166                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
 167
 168                 //Log("netmask = 0x%08x", netmask);
 169                 //Log("addr = 0x%08x", addr);
 170                 //Log("this = 0x%08x", this);
 171                 //Log("%08x == %08x && %08x == %08x",
 172                 //      (addr & netmask), (this & netmask),
 173                 //      (addr & ~netmask), (0xFFFFFFFF & ~netmask)
 174                 //      );
 175                 if( (addr & netmask) == (this & netmask)
 176                  && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 177                         return iface;
 178         }
 179         return NULL;
 180 }
 181
 182 /**
 183  * \brief Convert a network prefix to a netmask
 184  *
 185  * For example /24 will become 255.255.255.0
 186  */
 187 Uint32 IPv4_Netmask(int FixedBits)
 188 {
 189         Uint32  ret = 0xFFFFFFFF;
 190         ret >>= (32-FixedBits);
 191         ret <<= (32-FixedBits);
 192         // Returs a little endian netmask
 193         return ret;
 194 }
 195
 196 /**
 197  * \brief Calculate the IPv4 Checksum
 198  */
 199 Uint16 IPv4_Checksum(void *Buf, int Size)
 200 {
 201         Uint16  sum = 0;
 202         Uint16  *arr = Buf;
 203          int    i;
 204
 205         Log("IPv4_Checksum: (%p, %i)", Buf, Size);
 206
 207         Size = (Size + 1) >> 1;
 208         for(i = 0; i < Size; i++ )
 209         {
 210                 if((int)sum + arr[i] > 0xFFFF)
 211                         sum ++; // Simulate 1's complement
 212                 sum += arr[i];
 213         }
 214         return htons( ~sum );
 215 }
 216
 217 /**
 218  * \brief Sends an ICMP Echo and waits for a reply
 219  */
 220 int IPv4_Ping(tInterface *Iface, tIPv4 Addr)
 221 {
 222         return ICMP_Ping(Iface, Addr);
 223 }