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