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  * \param Iface Interface
  55  * \param Address       Destination IP
  56  * \param Protocol      Protocol ID
  57  * \param ID    Some random ID number
  58  * \param Length        Data Length
  59  * \param Data  Packet Data
  60  */
  61 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, void *Data)
  62 {
  63         tMacAddr        to = ARP_Resolve4(Iface, Address);
  64          int    bufSize = sizeof(tIPv4Header) + Length;
  65         char    buf[bufSize];
  66         tIPv4Header     *hdr = (void*)buf;
  67
  68         memcpy(&hdr->Options[0], Data, Length);
  69         hdr->Version = 4;
  70         hdr->HeaderLength = sizeof(tIPv4Header)/4;
  71         hdr->DiffServices = 0;  // TODO: Check
  72         hdr->TotalLength = htons( bufSize );
  73         hdr->Identifcation = htons( ID );       // TODO: Check
  74         hdr->TTL = DEFAULT_TTL;
  75         hdr->Protocol = Protocol;
  76         hdr->HeaderChecksum = 0;        // Will be set later
  77         hdr->Source = Iface->IP4.Address;
  78         hdr->Destination = Address;
  79         hdr->HeaderChecksum = IPv4_Checksum(hdr, sizeof(tIPv4Header));
  80
  81         Log("[IPv4 ] Sending packet to %i.%i.%i.%i",
  82                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
  83         Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, bufSize, buf);
  84         return 1;
  85 }
  86
  87 /**
  88  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
  89  * \brief Process an IPv4 Packet
  90  */
  91 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  92 {
  93         tIPv4Header     *hdr = Buffer;
  94         tInterface      *iface;
  95         Uint8   *data;
  96          int    dataLength;
  97         if(Length < sizeof(tIPv4Header))        return;
  98
  99         //Log("[IPv4 ] Version = %i", hdr->Version);
 100         Log("[IPv4 ] HeaderLength = %i", hdr->HeaderLength);
 101         Log("[IPv4 ] DiffServices = %i", hdr->DiffServices);
 102         Log("[IPv4 ] TotalLength = %i", ntohs(hdr->TotalLength) );
 103         //Log("[IPv4 ] Identifcation = %i", ntohs(hdr->Identifcation) );
 104         //Log("[IPv4 ] TTL = %i", hdr->TTL );
 105         Log("[IPv4 ] Protocol = %i", hdr->Protocol );
 106         //Log("[IPv4 ] HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
 107         Log("[IPv4 ] Source = %i.%i.%i.%i",
 108                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
 109         Log("[IPv4 ] Destination = %i.%i.%i.%i",
 110                 hdr->Destination.B[0], hdr->Destination.B[1],
 111                 hdr->Destination.B[2], hdr->Destination.B[3] );
 112
 113         // Check that the version IS IPv4
 114         if(hdr->Version != 4) {
 115                 Log("[IPv4 ] hdr->Version(%i) != 4", hdr->Version);
 116                 return;
 117         }
 118
 119         // Check Header checksum
 120         //TODO
 121
 122         // Check Packet length
 123         if( ntohs(hdr->TotalLength) > Length) {
 124                 Log("[IPv4 ] hdr->TotalLength(%i) > Length(%i)", ntohs(hdr->TotalLength), Length);
 125                 return;
 126         }
 127
 128         // Get Interface (allowing broadcasts)
 129         iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
 130         if(!iface) {
 131                 Log("[IPv4 ] Ignoring Packet (Not for us)");
 132                 return; // Not for us? Well, let's ignore it
 133         }
 134
 135         // Defragment
 136         //TODO
 137
 138         dataLength = ntohs(hdr->TotalLength) - sizeof(tIPv4Header);
 139         data = &hdr->Options[0];
 140
 141         // Send it on
 142         if( gaIPv4_Callbacks[hdr->Protocol] )
 143                 gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
 144         else
 145                 Log("[IPv4 ] Unknown Protocol %i", hdr->Protocol);
 146 }
 147
 148 /**
 149  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 150  * \brief Searches an adapter for a matching address
 151  */
 152 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 153 {
 154         tInterface      *iface = NULL;
 155         Uint32  netmask;
 156         Uint32  addr, this;
 157
 158         addr = ntohl( Address.L );
 159
 160         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 161         {
 162                 if( iface->Adapter != Adapter ) continue;
 163                 if( iface->Type != 4 )  continue;
 164                 if( IP4_EQU(Address, iface->IP4.Address) )
 165                         return iface;
 166
 167                 if( !Broadcast )        continue;
 168
 169                 this = ntohl( iface->IP4.Address.L );
 170
 171                 // Check for broadcast
 172                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
 173
 174                 //Log("netmask = 0x%08x", netmask);
 175                 //Log("addr = 0x%08x", addr);
 176                 //Log("this = 0x%08x", this);
 177                 //Log("%08x == %08x && %08x == %08x",
 178                 //      (addr & netmask), (this & netmask),
 179                 //      (addr & ~netmask), (0xFFFFFFFF & ~netmask)
 180                 //      );
 181                 if( (addr & netmask) == (this & netmask)
 182                  && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 183                         return iface;
 184         }
 185         return NULL;
 186 }
 187
 188 /**
 189  * \brief Convert a network prefix to a netmask
 190  *
 191  * For example /24 will become 255.255.255.0
 192  */
 193 Uint32 IPv4_Netmask(int FixedBits)
 194 {
 195         Uint32  ret = 0xFFFFFFFF;
 196         ret >>= (32-FixedBits);
 197         ret <<= (32-FixedBits);
 198         // Returs a little endian netmask
 199         return ret;
 200 }
 201
 202 /**
 203  * \brief Calculate the IPv4 Checksum
 204  */
 205 Uint16 IPv4_Checksum(void *Buf, int Size)
 206 {
 207         Uint16  sum = 0;
 208         Uint16  *arr = Buf;
 209          int    i;
 210
 211         Log("IPv4_Checksum: (%p, %i)", Buf, Size);
 212
 213         Size = (Size + 1) >> 1;
 214         for(i = 0; i < Size; i++ )
 215         {
 216                 if((int)sum + arr[i] > 0xFFFF)
 217                         sum ++; // Simulate 1's complement
 218                 sum += arr[i];
 219         }
 220         return ~sum ;
 221 }
 222
 223 /**
 224  * \brief Sends an ICMP Echo and waits for a reply
 225  */
 226 int IPv4_Ping(tInterface *Iface, tIPv4 Addr)
 227 {
 228         return ICMP_Ping(Iface, Addr);
 229 }