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 routing tables if not on this subnet
  81         if( IPStack_CompareAddress(4, &Address, Interface->Address, Interface->SubnetBits) == 0 )
  82         {
  83                 tRoute  *route = IPStack_FindRoute(4, Interface, &Address);
  84                 // If the next hop is defined, use it
  85                 // - 0.0.0.0 as the next hop means "no next hop / direct"
  86                 if( route && ((tIPv4*)route->NextHop)->L != 0 )
  87                 {
  88                         // Recursion: see /Recursion/
  89                         return ARP_Resolve4(Interface, *(tIPv4*)route->NextHop);
  90                 }
  91         }
  92
  93         // Check ARP Cache
  94         Mutex_Acquire( &glARP_Cache4 );
  95         for( i = 0; i < giARP_Cache4Space; i++ )
  96         {
  97                 if(gaARP_Cache4[i].IP.L != Address.L)   continue;
  98
  99                 // Check if the entry needs to be refreshed
 100                 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE )  break;
 101
 102                 Mutex_Release( &glARP_Cache4 );
 103                 LOG("Return %x:%x:%x:%x:%x:%x",
 104                         gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
 105                         gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
 106                         gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
 107                         );
 108                 LEAVE('-');
 109                 return gaARP_Cache4[i].MAC;
 110         }
 111         Mutex_Release( &glARP_Cache4 );
 112
 113         lastID = giARP_LastUpdateID;
 114
 115         // Create request
 116         Log_Log("ARP4", "Asking for address %i.%i.%i.%i",
 117                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]
 118                 );
 119         req.HWType = htons(0x0001);     // Ethernet
 120         req.Type   = htons(0x0800);
 121         req.HWSize = 6;
 122         req.SWSize = 4;
 123         req.Request = htons(1);
 124         req.SourceMac = Interface->Adapter->MacAddr;
 125         req.SourceIP = *(tIPv4*)Interface->Address;
 126         req.DestMac = cMAC_BROADCAST;
 127         req.DestIP = Address;
 128
 129         // Send Request
 130         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
 131
 132         timeout = now() + Interface->TimeoutDelay;
 133
 134         // Wait for a reply
 135         for(;;)
 136         {
 137                 while(lastID == giARP_LastUpdateID && now() < timeout) {
 138                         Threads_Yield();
 139                 }
 140
 141                 if( now() >= timeout ) {
 142                         Log_Log("ARP4", "Timeout");
 143                         break;  // Timeout
 144                 }
 145
 146                 lastID = giARP_LastUpdateID;
 147
 148                 Mutex_Acquire( &glARP_Cache4 );
 149                 for( i = 0; i < giARP_Cache4Space; i++ )
 150                 {
 151                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 152
 153                         Mutex_Release( &glARP_Cache4 );
 154                         Log_Debug("ARP4", "Return %02x:%02x:%02x:%02x:%02x:%02x",
 155                                 gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
 156                                 gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
 157                                 gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]);
 158                         return gaARP_Cache4[i].MAC;
 159                 }
 160                 Mutex_Release( &glARP_Cache4 );
 161         }
 162         {
 163                 tMacAddr        ret = {{0,0,0,0,0,0}};
 164                 return ret;
 165         }
 166 }
 167
 168 /**
 169  * \brief Updates the ARP Cache entry for an IPv4 Address
 170  */
 171 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 172 {
 173          int    i;
 174          int    free = -1;
 175          int    oldest = 0;
 176
 177         // Find an entry for the IP address in the cache
 178         Mutex_Acquire(&glARP_Cache4);
 179         for( i = giARP_Cache4Space; i--; )
 180         {
 181                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 182                         oldest = i;
 183                 }
 184                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 185                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 186         }
 187         // If there was no match, we need to make one
 188         if(i == -1) {
 189                 if(free != -1)
 190                         i = free;
 191                 else
 192                         i = oldest;
 193         }
 194
 195         Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
 196                 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
 197                 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
 198                 i
 199                 );
 200
 201         gaARP_Cache4[i].IP = SWAddr;
 202         gaARP_Cache4[i].MAC = HWAddr;
 203         gaARP_Cache4[i].LastUpdate = now();
 204         giARP_LastUpdateID ++;
 205         Mutex_Release(&glARP_Cache4);
 206 }
 207
 208 #if ARPv6
 209 /**
 210  * \brief Updates the ARP Cache entry for an IPv6 Address
 211  */
 212 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 213 {
 214          int    i;
 215          int    free = -1;
 216          int    oldest = 0;
 217
 218         // Find an entry for the MAC address in the cache
 219         Mutex_Acquire(&glARP_Cache6);
 220         for( i = giARP_Cache6Space; i--; )
 221         {
 222                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 223                         oldest = i;
 224                 }
 225                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 226                 if( gaARP_Cache6[i].LastUpdate == 0 && free == -1 )     free = i;
 227         }
 228         // If there was no match, we need to make one
 229         if(i == -1) {
 230                 if(free != -1)
 231                         i = free;
 232                 else
 233                         i = oldest;
 234                 gaARP_Cache6[i].MAC = HWAddr;
 235         }
 236
 237         gaARP_Cache6[i].IP = SWAddr;
 238         gaARP_Cache6[i].LastUpdate = now();
 239         giARP_LastUpdateID ++;
 240         Mutex_Release(&glARP_Cache6);
 241 }
 242 #endif
 243
 244 /**
 245  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 246  * \brief Called when an ARP packet is recieved
 247  */
 248 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 249 {
 250         tArpRequest4    *req4 = Buffer;
 251         #if ARPv6
 252         tArpRequest6    *req6 = Buffer;
 253         #endif
 254         tInterface      *iface;
 255
 256         // Sanity Check Packet
 257         if( Length < (int)sizeof(tArpRequest4) ) {
 258                 Log_Log("ARP", "Recieved undersized packet");
 259                 return ;
 260         }
 261         if( ntohs(req4->Type) != 0x0800 ) {
 262                 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
 263                 return ;
 264         }
 265         if( req4->HWSize != 6 ) {
 266                 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 267                 return;
 268         }
 269         #if ARP_DETECT_SPOOFS
 270         if( !MAC_EQU(req4->SourceMac, From) ) {
 271                 Log_Log("ARP", "ARP spoofing detected "
 272                         "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
 273                         req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
 274                         req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
 275                         From.B[0], From.B[1], From.B[2],
 276                         From.B[3], From.B[4], From.B[5]
 277                         );
 278                 return;
 279         }
 280         #endif
 281
 282         switch( ntohs(req4->Request) )
 283         {
 284         case 1: // You want my IP?
 285                 // Check what type of IP it is
 286                 switch( req4->SWSize )
 287                 {
 288                 case 4:
 289                         Log_Debug("ARP", "ARP Request IPv4 Address %i.%i.%i.%i from %i.%i.%i.%i",
 290                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 291                                 req4->DestIP.B[3],
 292                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 293                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 294                         Log_Debug("ARP", " from MAC %02x:%02x:%02x:%02x:%02x:%02x",
 295                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 296                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 297                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 298                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 299                         if( iface )
 300                         {
 301                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 302
 303                                 req4->DestIP = req4->SourceIP;
 304                                 req4->DestMac = req4->SourceMac;
 305                                 req4->SourceIP = *(tIPv4*)iface->Address;;
 306                                 req4->SourceMac = Adapter->MacAddr;
 307                                 req4->Request = htons(2);
 308                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 309                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 310                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 311                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 312                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 313                         }
 314                         break;
 315                 #if ARPv6
 316                 case 6:
 317                         if( Length < (int)sizeof(tArpRequest6) ) {
 318                                 Log_Log("ARP", "Recieved undersized packet (IPv6)");
 319                                 return ;
 320                         }
 321                         Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
 322                                 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
 323                                 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
 324                                 );
 325                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 326                         if( iface )
 327                         {
 328                                 req6->DestIP = req6->SourceIP;
 329                                 req6->DestMac = req6->SourceMac;
 330                                 req6->SourceIP = *(tIPv6*)iface->Address;
 331                                 req6->SourceMac = Adapter->MacAddr;
 332                                 req6->Request = htons(2);
 333                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 334                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 335                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 336                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 337                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 338                         }
 339                         break;
 340                 #endif
 341                 default:
 342                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 343                         return ;
 344                 }
 345
 346                 break;
 347
 348         case 2: // Ooh! A response!
 349                 // Check what type of IP it is
 350                 switch( req4->SWSize )
 351                 {
 352                 case 4:
 353                         ARP_UpdateCache4( req4->SourceIP, From );
 354                         break;
 355                 #if ARPv6
 356                 case 6:
 357                         if( Length < (int)sizeof(tArpRequest6) ) {
 358                                 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
 359                                 return ;
 360                         }
 361                         ARP_UpdateCache6( req6->SourceIP, From );
 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         default:
 372                 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));
 373                 break;
 374         }
 375 }