Modules/IPStack/arp.c

   1 /*
   2  * Acess2 IP Stack
   3  * - Address Resolution Protocol
   4  * - Part of the IPv4 protocol
   5  */
   6 #define DEBUG   0
   7 #include "ipstack.h"
   8 #include "arp.h"
   9 #include "link.h"
  10
  11 #define ARPv6   0
  12 #define ARP_CACHE_SIZE  64
  13 #define ARP_MAX_AGE             (60*60*1000)    // 1Hr
  14
  15 // === IMPORTS ===
  16 extern tInterface       *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  17 #if ARPv6
  18 extern tInterface       *IPv6_GetInterface(tAdapter *Adapter, tIPv6 Address, int Broadcast);
  19 #endif
  20
  21 // === PROTOTYPES ===
  22  int    ARP_Initialise();
  23 tMacAddr        ARP_Resolve4(tInterface *Interface, tIPv4 Address);
  24 void    ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer);
  25
  26 // === GLOBALS ===
  27 struct sARP_Cache4 {
  28         tIPv4   IP;
  29         tMacAddr        MAC;
  30         Sint64  LastUpdate;
  31         Sint64  LastUsed;
  32 }       *gaARP_Cache4;
  33  int    giARP_Cache4Space;
  34 tMutex  glARP_Cache4;
  35 #if ARPv6
  36 struct sARP_Cache6 {
  37         tIPv6   IP;
  38         tMacAddr        MAC;
  39         Sint64  LastUpdate;
  40         Sint64  LastUsed;
  41 }       *gaARP_Cache6;
  42  int    giARP_Cache6Space;
  43 tMutex  glARP_Cache6;
  44 #endif
  45 volatile int    giARP_LastUpdateID = 0;
  46
  47 // === CODE ===
  48 /**
  49  * \fn int ARP_Initialise()
  50  * \brief Initalise the ARP section
  51  */
  52 int ARP_Initialise()
  53 {
  54         gaARP_Cache4 = malloc( ARP_CACHE_SIZE * sizeof(struct sARP_Cache4) );
  55         memset( gaARP_Cache4, 0, ARP_CACHE_SIZE * sizeof(struct sARP_Cache4) );
  56         giARP_Cache4Space = ARP_CACHE_SIZE;
  57
  58         #if ARPv6
  59         gaARP_Cache6 = malloc( ARP_CACHE_SIZE * sizeof(struct sARP_Cache6) );
  60         memset( gaARP_Cache6, 0, ARP_CACHE_SIZE * sizeof(struct sARP_Cache6) );
  61         giARP_Cache6Space = ARP_CACHE_SIZE;
  62         #endif
  63
  64         Link_RegisterType(0x0806, ARP_int_GetPacket);
  65         return 1;
  66 }
  67
  68 /**
  69  * \brief Resolves a MAC address from an IPv4 address
  70  */
  71 tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address)
  72 {
  73          int    lastID;
  74          int    i;
  75         struct sArpRequest4     req;
  76         Sint64  timeout;
  77
  78         ENTER("pInterface xAddress", Interface, Address);
  79
  80         // Check for broadcast
  81         if( Address.L == -1 )
  82         {
  83                 LOG("Broadcast");
  84                 LEAVE('-');
  85                 return cMAC_BROADCAST;
  86         }
  87
  88         // Check routing tables if not on this subnet
  89         if( IPStack_CompareAddress(4, &Address, Interface->Address, Interface->SubnetBits) == 0 )
  90         {
  91                 tRoute  *route = IPStack_FindRoute(4, Interface, &Address);
  92                 // If the next hop is defined, use it
  93                 // - 0.0.0.0 as the next hop means "no next hop / direct"
  94                 if( route && ((tIPv4*)route->NextHop)->L != 0 )
  95                 {
  96                         // Recursion: see /Recursion/
  97                         LOG("Recursing with %s", IPStack_PrintAddress(4, route->NextHop));
  98                         LEAVE('-');
  99                         return ARP_Resolve4(Interface, *(tIPv4*)route->NextHop);
 100                 }
 101                 // No route, fall though
 102         }
 103         else
 104         {
 105                 Uint32  netmask;
 106                 // Check for broadcast
 107                 netmask = IPv4_Netmask(Interface->SubnetBits);
 108                 if( (Address.L & ~netmask) == (0xFFFFFFFF & ~netmask) )
 109                 {
 110                         LOG("Local Broadcast");
 111                         LEAVE('-');
 112                         return cMAC_BROADCAST;
 113                 }
 114         }
 115
 116         // Check ARP Cache
 117         Mutex_Acquire( &glARP_Cache4 );
 118         for( i = 0; i < giARP_Cache4Space; i++ )
 119         {
 120                 if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 121
 122                 // Check if the entry needs to be refreshed
 123                 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE )  break;
 124
 125                 Mutex_Release( &glARP_Cache4 );
 126                 LOG("Return %x:%x:%x:%x:%x:%x",
 127                         gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
 128                         gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
 129                         gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
 130                         );
 131                 LEAVE('-');
 132                 return gaARP_Cache4[i].MAC;
 133         }
 134         Mutex_Release( &glARP_Cache4 );
 135
 136         lastID = giARP_LastUpdateID;
 137
 138         // Create request
 139         Log_Log("ARP4", "Asking for address %i.%i.%i.%i",
 140                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]
 141                 );
 142         req.HWType = htons(0x0001);     // Ethernet
 143         req.Type   = htons(0x0800);
 144         req.HWSize = 6;
 145         req.SWSize = 4;
 146         req.Request = htons(1);
 147         req.SourceMac = Interface->Adapter->MacAddr;
 148         req.SourceIP = *(tIPv4*)Interface->Address;
 149         req.DestMac = cMAC_BROADCAST;
 150         req.DestIP = Address;
 151
 152         // Send Request
 153         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
 154
 155         timeout = now() + Interface->TimeoutDelay;
 156
 157         // Wait for a reply
 158         for(;;)
 159         {
 160                 while(lastID == giARP_LastUpdateID && now() < timeout) {
 161                         Threads_Yield();
 162                 }
 163
 164                 if( now() >= timeout ) {
 165                         Log_Log("ARP4", "Timeout");
 166                         break;  // Timeout
 167                 }
 168
 169                 lastID = giARP_LastUpdateID;
 170
 171                 Mutex_Acquire( &glARP_Cache4 );
 172                 for( i = 0; i < giARP_Cache4Space; i++ )
 173                 {
 174                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 175
 176                         Mutex_Release( &glARP_Cache4 );
 177                         Log_Debug("ARP4", "Return %02x:%02x:%02x:%02x:%02x:%02x",
 178                                 gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
 179                                 gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
 180                                 gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]);
 181                         return gaARP_Cache4[i].MAC;
 182                 }
 183                 Mutex_Release( &glARP_Cache4 );
 184         }
 185         {
 186                 tMacAddr        ret = {{0,0,0,0,0,0}};
 187                 return ret;
 188         }
 189 }
 190
 191 /**
 192  * \brief Updates the ARP Cache entry for an IPv4 Address
 193  */
 194 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 195 {
 196          int    i;
 197          int    free = -1;
 198          int    oldest = 0;
 199
 200         // Find an entry for the IP address in the cache
 201         Mutex_Acquire(&glARP_Cache4);
 202         for( i = giARP_Cache4Space; i--; )
 203         {
 204                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 205                         oldest = i;
 206                 }
 207                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 208                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 209         }
 210         // If there was no match, we need to make one
 211         if(i == -1) {
 212                 if(free != -1)
 213                         i = free;
 214                 else
 215                         i = oldest;
 216         }
 217
 218         Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
 219                 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
 220                 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
 221                 i
 222                 );
 223
 224         gaARP_Cache4[i].IP = SWAddr;
 225         gaARP_Cache4[i].MAC = HWAddr;
 226         gaARP_Cache4[i].LastUpdate = now();
 227         giARP_LastUpdateID ++;
 228         Mutex_Release(&glARP_Cache4);
 229 }
 230
 231 #if ARPv6
 232 /**
 233  * \brief Updates the ARP Cache entry for an IPv6 Address
 234  */
 235 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 236 {
 237          int    i;
 238          int    free = -1;
 239          int    oldest = 0;
 240
 241         // Find an entry for the MAC address in the cache
 242         Mutex_Acquire(&glARP_Cache6);
 243         for( i = giARP_Cache6Space; i--; )
 244         {
 245                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 246                         oldest = i;
 247                 }
 248                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 249                 if( gaARP_Cache6[i].LastUpdate == 0 && free == -1 )     free = i;
 250         }
 251         // If there was no match, we need to make one
 252         if(i == -1) {
 253                 if(free != -1)
 254                         i = free;
 255                 else
 256                         i = oldest;
 257                 gaARP_Cache6[i].MAC = HWAddr;
 258         }
 259
 260         gaARP_Cache6[i].IP = SWAddr;
 261         gaARP_Cache6[i].LastUpdate = now();
 262         giARP_LastUpdateID ++;
 263         Mutex_Release(&glARP_Cache6);
 264 }
 265 #endif
 266
 267 /**
 268  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 269  * \brief Called when an ARP packet is recieved
 270  */
 271 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 272 {
 273         tArpRequest4    *req4 = Buffer;
 274         #if ARPv6
 275         tArpRequest6    *req6 = Buffer;
 276         #endif
 277         tInterface      *iface;
 278
 279         // Sanity Check Packet
 280         if( Length < (int)sizeof(tArpRequest4) ) {
 281                 Log_Log("ARP", "Recieved undersized packet");
 282                 return ;
 283         }
 284         if( ntohs(req4->Type) != 0x0800 ) {
 285                 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
 286                 return ;
 287         }
 288         if( req4->HWSize != 6 ) {
 289                 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 290                 return;
 291         }
 292         #if ARP_DETECT_SPOOFS
 293         if( !MAC_EQU(req4->SourceMac, From) ) {
 294                 Log_Log("ARP", "ARP spoofing detected "
 295                         "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
 296                         req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
 297                         req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
 298                         From.B[0], From.B[1], From.B[2],
 299                         From.B[3], From.B[4], From.B[5]
 300                         );
 301                 return;
 302         }
 303         #endif
 304
 305         switch( ntohs(req4->Request) )
 306         {
 307         case 1: // You want my IP?
 308                 // Check what type of IP it is
 309                 switch( req4->SWSize )
 310                 {
 311                 case 4:
 312                         Log_Debug("ARP", "ARP Request IPv4 Address %i.%i.%i.%i from %i.%i.%i.%i",
 313                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 314                                 req4->DestIP.B[3],
 315                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 316                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 317                         Log_Debug("ARP", " from MAC %02x:%02x:%02x:%02x:%02x:%02x",
 318                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 319                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 320                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 321                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 322                         if( iface )
 323                         {
 324                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 325
 326                                 req4->DestIP = req4->SourceIP;
 327                                 req4->DestMac = req4->SourceMac;
 328                                 req4->SourceIP = *(tIPv4*)iface->Address;;
 329                                 req4->SourceMac = Adapter->MacAddr;
 330                                 req4->Request = htons(2);
 331                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 332                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 333                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 334                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 335                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 336                         }
 337                         break;
 338                 #if ARPv6
 339                 case 6:
 340                         if( Length < (int)sizeof(tArpRequest6) ) {
 341                                 Log_Log("ARP", "Recieved undersized packet (IPv6)");
 342                                 return ;
 343                         }
 344                         Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
 345                                 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
 346                                 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
 347                                 );
 348                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 349                         if( iface )
 350                         {
 351                                 req6->DestIP = req6->SourceIP;
 352                                 req6->DestMac = req6->SourceMac;
 353                                 req6->SourceIP = *(tIPv6*)iface->Address;
 354                                 req6->SourceMac = Adapter->MacAddr;
 355                                 req6->Request = htons(2);
 356                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 357                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 358                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 359                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 360                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 361                         }
 362                         break;
 363                 #endif
 364                 default:
 365                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 366                         return ;
 367                 }
 368
 369                 break;
 370
 371         case 2: // Ooh! A response!
 372                 // Check what type of IP it is
 373                 switch( req4->SWSize )
 374                 {
 375                 case 4:
 376                         ARP_UpdateCache4( req4->SourceIP, From );
 377                         break;
 378                 #if ARPv6
 379                 case 6:
 380                         if( Length < (int)sizeof(tArpRequest6) ) {
 381                                 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
 382                                 return ;
 383                         }
 384                         ARP_UpdateCache6( req6->SourceIP, From );
 385                         break;
 386                 #endif
 387                 default:
 388                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 389                         return ;
 390                 }
 391
 392                 break;
 393
 394         default:
 395                 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));
 396                 break;
 397         }
 398 }