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  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
  77         ENTER("pInterface xAddress", Interface, Address);
  78
  79         // Check routing tables if not on this subnet
  80         if( IPStack_CompareAddress(4, &Address, Interface->Address, Interface->SubnetBits) == 0 )
  81         {
  82                 tRoute  *route = IPStack_FindRoute(4, Interface, &Address);
  83                 if( route ) {
  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( ((tIPv4*)route->NextHop)->L != 0 ) {
  87                                 // Recursion: see /Recursion/
  88                                 return ARP_Resolve4(Interface, *(tIPv4*)route->NextHop);
  89                         }
  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         // Wait for a reply
 133         for(;;)
 134         {
 135                 while(lastID == giARP_LastUpdateID)     Threads_Yield();
 136                 lastID = giARP_LastUpdateID;
 137
 138                 Mutex_Acquire( &glARP_Cache4 );
 139                 for( i = 0; i < giARP_Cache4Space; i++ )
 140                 {
 141                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 142
 143                         Mutex_Release( &glARP_Cache4 );
 144                         return gaARP_Cache4[i].MAC;
 145                 }
 146                 Mutex_Release( &glARP_Cache4 );
 147         }
 148 }
 149
 150 /**
 151  * \brief Updates the ARP Cache entry for an IPv4 Address
 152  */
 153 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 154 {
 155          int    i;
 156          int    free = -1;
 157          int    oldest = 0;
 158
 159         // Find an entry for the IP address in the cache
 160         Mutex_Acquire(&glARP_Cache4);
 161         for( i = giARP_Cache4Space; i--; )
 162         {
 163                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 164                         oldest = i;
 165                 }
 166                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 167                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 168         }
 169         // If there was no match, we need to make one
 170         if(i == -1) {
 171                 if(free != -1)
 172                         i = free;
 173                 else
 174                         i = oldest;
 175                 gaARP_Cache4[i].IP = SWAddr;
 176         }
 177
 178         Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
 179                 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
 180                 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
 181                 i
 182                 );
 183
 184         gaARP_Cache4[i].MAC = HWAddr;
 185         gaARP_Cache4[i].LastUpdate = now();
 186         giARP_LastUpdateID ++;
 187         Mutex_Release(&glARP_Cache4);
 188 }
 189
 190 #if ARPv6
 191 /**
 192  * \brief Updates the ARP Cache entry for an IPv6 Address
 193  */
 194 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 195 {
 196          int    i;
 197          int    free = -1;
 198          int    oldest = 0;
 199
 200         // Find an entry for the MAC address in the cache
 201         Mutex_Acquire(&glARP_Cache6);
 202         for( i = giARP_Cache6Space; i--; )
 203         {
 204                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 205                         oldest = i;
 206                 }
 207                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 208                 if( gaARP_Cache6[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                 gaARP_Cache6[i].MAC = HWAddr;
 217         }
 218
 219         gaARP_Cache6[i].IP = SWAddr;
 220         gaARP_Cache6[i].LastUpdate = now();
 221         giARP_LastUpdateID ++;
 222         Mutex_Release(&glARP_Cache6);
 223 }
 224 #endif
 225
 226 /**
 227  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 228  * \brief Called when an ARP packet is recieved
 229  */
 230 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 231 {
 232         tArpRequest4    *req4 = Buffer;
 233         #if ARPv6
 234         tArpRequest6    *req6 = Buffer;
 235         #endif
 236         tInterface      *iface;
 237
 238         // Sanity Check Packet
 239         if( Length < (int)sizeof(tArpRequest4) ) {
 240                 Log_Log("ARP", "Recieved undersized packet");
 241                 return ;
 242         }
 243         if( ntohs(req4->Type) != 0x0800 ) {
 244                 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
 245                 return ;
 246         }
 247         if( req4->HWSize != 6 ) {
 248                 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 249                 return;
 250         }
 251         #if ARP_DETECT_SPOOFS
 252         if( !MAC_EQU(req4->SourceMac, From) ) {
 253                 Log_Log("ARP", "ARP spoofing detected "
 254                         "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
 255                         req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
 256                         req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
 257                         From.B[0], From.B[1], From.B[2],
 258                         From.B[3], From.B[4], From.B[5]
 259                         );
 260                 return;
 261         }
 262         #endif
 263
 264         Log_Debug("ARP", "Request ID %i", ntohs(req4->Request));
 265
 266         switch( ntohs(req4->Request) )
 267         {
 268         case 1: // You want my IP?
 269                 Log_Debug("ARP", "ARP Request Address class %i", req4->SWSize);
 270                 // Check what type of IP it is
 271                 switch( req4->SWSize )
 272                 {
 273                 case 4:
 274                         Log_Debug("ARP", "From MAC %02x:%02x:%02x:%02x:%02x:%02x",
 275                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 276                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 277                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 278                         //Log_Debug("ARP", "to MAC %02x:%02x:%02x:%02x:%02x:%02x",
 279                         //      req4->DestMac.B[0], req4->DestMac.B[1],
 280                         //      req4->DestMac.B[2], req4->DestMac.B[3],
 281                         //      req4->DestMac.B[4], req4->DestMac.B[5]);
 282                         Log_Debug("ARP", "ARP Request IPv4 Address %i.%i.%i.%i from %i.%i.%i.%i",
 283                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 284                                 req4->DestIP.B[3],
 285                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 286                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 287                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 288                         if( iface )
 289                         {
 290                                 Log_Debug("ARP", "Caching sender's IP Address");
 291                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 292
 293                                 req4->DestIP = req4->SourceIP;
 294                                 req4->DestMac = req4->SourceMac;
 295                                 req4->SourceIP = *(tIPv4*)iface->Address;;
 296                                 req4->SourceMac = Adapter->MacAddr;
 297                                 req4->Request = htons(2);
 298                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 299                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 300                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 301                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 302                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 303                         }
 304                         break;
 305                 #if ARPv6
 306                 case 6:
 307                         if( Length < (int)sizeof(tArpRequest6) ) {
 308                                 Log_Log("ARP", "Recieved undersized packet (IPv6)");
 309                                 return ;
 310                         }
 311                         Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
 312                                 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
 313                                 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
 314                                 );
 315                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 316                         if( iface )
 317                         {
 318                                 req6->DestIP = req6->SourceIP;
 319                                 req6->DestMac = req6->SourceMac;
 320                                 req6->SourceIP = *(tIPv6*)iface->Address;
 321                                 req6->SourceMac = Adapter->MacAddr;
 322                                 req6->Request = htons(2);
 323                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 324                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 325                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 326                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 327                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 328                         }
 329                         break;
 330                 #endif
 331                 default:
 332                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 333                         return ;
 334                 }
 335
 336                 break;
 337
 338         case 2: // Ooh! A response!
 339                 // Check what type of IP it is
 340                 switch( req4->SWSize )
 341                 {
 342                 case 4:
 343                         ARP_UpdateCache4( req4->SourceIP, From );
 344                         break;
 345                 #if ARPv6
 346                 case 6:
 347                         if( Length < (int)sizeof(tArpRequest6) ) {
 348                                 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
 349                                 return ;
 350                         }
 351                         ARP_UpdateCache6( req6->SourceIP, From );
 352                         break;
 353                 #endif
 354                 default:
 355                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 356                         return ;
 357                 }
 358
 359                 break;
 360
 361         default:
 362                 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));
 363                 break;
 364         }
 365 }