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