Modules/IPStack/link.c

   1 /*
   2  * Acess2 IP Stack
   3  * - Link/Media Layer Interface
   4  */
   5 #include "ipstack.h"
   6 #include "link.h"
   7
   8 // === CONSTANTS ===
   9 #define MAX_PACKET_SIZE 2048
  10
  11 // === PROTOTYPES ===
  12 void    Link_RegisterType(Uint16 Type, tPacketCallback Callback);
  13 void    Link_InitCRC();
  14 Uint32  Link_CalculateCRC(void *Data, int Length);
  15 void    Link_SendPacket(tAdapter *Adapter, Uint16 Type, tMacAddr To, int Length, void *Buffer);
  16 void    Link_WatchDevice(tAdapter *Adapter);
  17
  18 // === GLOBALS ===
  19  int    giRegisteredTypes = 0;
  20  int    giRegisteredTypeSpace = 0;
  21 struct {
  22         Uint16  Type;
  23         tPacketCallback Callback;
  24 }       *gaRegisteredTypes;
  25  int    gbLink_CRCTableGenerated = 0;
  26 Uint32  gaiLink_CRCTable[256];
  27
  28 // === CODE ===
  29 /**
  30  * \fn void Link_RegisterType(Uint16 Type, tPacketCallback Callback)
  31  * \brief Registers a callback for a specific packet type
  32  *
  33  * \todo Make thread safe (place a mutex on the list)
  34  */
  35 void Link_RegisterType(Uint16 Type, tPacketCallback Callback)
  36 {
  37          int    i;
  38         void    *tmp;
  39
  40         Type = htons(Type);     // Set to network order
  41
  42         for( i = giRegisteredTypes; i -- ; )
  43         {
  44                 if(gaRegisteredTypes[i].Type == Type) {
  45                         Log_Warning("NET", "Attempt to register 0x%x twice", Type);
  46                         return ;
  47                 }
  48                 // Ooh! Free slot!
  49                 if(gaRegisteredTypes[i].Callback == NULL)       break;
  50         }
  51
  52         if(i == -1)
  53         {
  54                 giRegisteredTypeSpace += 5;
  55                 tmp = realloc(gaRegisteredTypes, giRegisteredTypeSpace*sizeof(*gaRegisteredTypes));
  56                 if(!tmp) {
  57                         Log_Warning("NET",
  58                                 "Out of heap space! (Attempted to allocate %i)",
  59                                 giRegisteredTypeSpace*sizeof(*gaRegisteredTypes)
  60                                 );
  61                         return ;
  62                 }
  63                 gaRegisteredTypes = tmp;
  64                 i = giRegisteredTypes;
  65                 giRegisteredTypes ++;
  66         }
  67
  68         gaRegisteredTypes[i].Callback = Callback;
  69         gaRegisteredTypes[i].Type = Type;
  70 }
  71
  72 /**
  73  * \fn void Link_SendPacket(tAdapter *Adapter, Uint16 Type, tMacAddr To, int Length, void *Buffer)
  74  * \brief Formats and sends a packet on the specified interface
  75  */
  76 void Link_SendPacket(tAdapter *Adapter, Uint16 Type, tMacAddr To, int Length, void *Buffer)
  77 {
  78          int    bufSize = sizeof(tEthernetHeader) + ((Length+3)&~3) + 4;
  79         Uint8   buf[bufSize];   // dynamic stack arrays ftw!
  80         tEthernetHeader *hdr = (void*)buf;
  81
  82         Log_Log("NET", "Sending %i bytes to %02x:%02x:%02x:%02x:%02x:%02x (Type 0x%x)",
  83                 Length, To.B[0], To.B[1], To.B[2], To.B[3], To.B[4], To.B[5], Type);
  84
  85         hdr->Dest = To;
  86         hdr->Src = Adapter->MacAddr;
  87         hdr->Type = htons(Type);
  88
  89         memcpy(hdr->Data, Buffer, Length);
  90
  91         *(Uint32*) &hdr->Data[bufSize-4] = 0;
  92         *(Uint32*) &hdr->Data[bufSize-4] = htonl( Link_CalculateCRC(buf, bufSize) );
  93
  94         VFS_Write(Adapter->DeviceFD, bufSize, buf);
  95 }
  96
  97 /**
  98  * \fn void Link_WatchDevice(tAdapter *Adapter)
  99  * \brief Spawns a worker thread to watch the specified adapter
 100  */
 101 void Link_WatchDevice(tAdapter *Adapter)
 102 {
 103          int    tid = Proc_SpawnWorker();       // Create a new worker thread
 104
 105         if(tid < 0) {
 106                 Log_Warning("NET", "Unable to create watcher thread for '%s'", Adapter->Device);
 107                 return ;
 108         }
 109
 110         if(tid > 0) {
 111                 Log_Log("NET", "Watching '%s' using tid %i", Adapter->Device, tid);
 112                 return ;
 113         }
 114
 115         if( !gbLink_CRCTableGenerated )
 116                 Link_InitCRC();
 117
 118         // Child Thread
 119         while(Adapter->DeviceFD != -1)
 120         {
 121                 Uint8   buf[MAX_PACKET_SIZE];
 122                 tEthernetHeader *hdr = (void*)buf;
 123                  int    ret, i;
 124                 Uint32  checksum;
 125
 126                 // Wait for a packet (Read on a network device is blocking)
 127                 ret = VFS_Read(Adapter->DeviceFD, MAX_PACKET_SIZE, buf);
 128                 if(ret == -1)   break;
 129
 130                 if(ret <= (int)sizeof(tEthernetHeader)) {
 131                         Log_Log("NET", "Recieved an undersized packet");
 132                         continue;
 133                 }
 134
 135                 Log_Log("NET", "Packet from %02x:%02x:%02x:%02x:%02x:%02x",
 136                         hdr->Src.B[0], hdr->Src.B[1], hdr->Src.B[2],
 137                         hdr->Src.B[3], hdr->Src.B[4], hdr->Src.B[5]
 138                         );
 139                 Log_Log("NET", "to %02x:%02x:%02x:%02x:%02x:%02x",
 140                         hdr->Dest.B[0], hdr->Dest.B[1], hdr->Dest.B[2],
 141                         hdr->Dest.B[3], hdr->Dest.B[4], hdr->Dest.B[5]
 142                         );
 143                 checksum = *(Uint32*)&hdr->Data[ret-sizeof(tEthernetHeader)-4];
 144                 Log_Log("NET", "Checksum 0x%08x", checksum);
 145
 146                 // Check if there is a registered callback for this packet type
 147                 for( i = giRegisteredTypes; i--; )
 148                 {
 149                         if(gaRegisteredTypes[i].Type == hdr->Type)      break;
 150                 }
 151                 // No? Ignore it
 152                 if( i == -1 ) {
 153                         Log_Log("NET", "Unregistered type 0x%x", ntohs(hdr->Type));
 154                         continue;
 155                 }
 156
 157                 // Call the callback
 158                 gaRegisteredTypes[i].Callback(
 159                         Adapter,
 160                         hdr->Src,
 161                         ret - sizeof(tEthernetHeader),
 162                         hdr->Data
 163                         );
 164         }
 165
 166         Log_Log("NET", "Watcher terminated (file closed)");
 167
 168         Threads_Exit(0, 0);
 169 }
 170
 171 // From http://www.cl.cam.ac.uk/research/srg/bluebook/21/crc/node6.html
 172 #define QUOTIENT        0x04c11db7
 173 void Link_InitCRC(void)
 174 {
 175      int        i, j;
 176     Uint32      crc;
 177
 178     for (i = 0; i < 256; i++)
 179     {
 180         crc = i << 24;
 181         for (j = 0; j < 8; j++)
 182         {
 183             if (crc & 0x80000000)
 184                 crc = (crc << 1) ^ QUOTIENT;
 185             else
 186                 crc = crc << 1;
 187         }
 188         gaiLink_CRCTable[i] = crc;
 189     }
 190
 191         gbLink_CRCTableGenerated = 1;
 192 }
 193
 194 Uint32 Link_CalculateCRC(void *Data, int Length)
 195 {
 196         // x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1
 197         Uint32  result;
 198      int        i;
 199         Uint32  *data = Data;
 200
 201     if(Length < 4)      return 0;
 202
 203     result = *data++ << 24;
 204     result |= *data++ << 16;
 205     result |= *data++ << 8;
 206     result |= *data++;
 207     result = ~ result;
 208     Length -= 4;
 209
 210     for( i = 0; i < Length; i++ )
 211     {
 212         result = (result << 8 | *data++) ^ gaiLink_CRCTable[result >> 24];
 213     }
 214
 215     return ~result;
 216 }