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         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                 if( now() >= timeout )  break;  // Timeout
 141
 142                 lastID = giARP_LastUpdateID;
 143
 144                 Mutex_Acquire( &glARP_Cache4 );
 145                 for( i = 0; i < giARP_Cache4Space; i++ )
 146                 {
 147                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 148
 149                         Mutex_Release( &glARP_Cache4 );
 150                         return gaARP_Cache4[i].MAC;
 151                 }
 152                 Mutex_Release( &glARP_Cache4 );
 153         }
 154         {
 155                 tMacAddr        ret = {{0,0,0,0,0,0}};
 156                 return ret;
 157         }
 158 }
 159
 160 /**
 161  * \brief Updates the ARP Cache entry for an IPv4 Address
 162  */
 163 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 164 {
 165          int    i;
 166          int    free = -1;
 167          int    oldest = 0;
 168
 169         // Find an entry for the IP address in the cache
 170         Mutex_Acquire(&glARP_Cache4);
 171         for( i = giARP_Cache4Space; i--; )
 172         {
 173                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 174                         oldest = i;
 175                 }
 176                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 177                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 178         }
 179         // If there was no match, we need to make one
 180         if(i == -1) {
 181                 if(free != -1)
 182                         i = free;
 183                 else
 184                         i = oldest;
 185                 gaARP_Cache4[i].IP = SWAddr;
 186         }
 187
 188         Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
 189                 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
 190                 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
 191                 i
 192                 );
 193
 194         gaARP_Cache4[i].MAC = HWAddr;
 195         gaARP_Cache4[i].LastUpdate = now();
 196         giARP_LastUpdateID ++;
 197         Mutex_Release(&glARP_Cache4);
 198 }
 199
 200 #if ARPv6
 201 /**
 202  * \brief Updates the ARP Cache entry for an IPv6 Address
 203  */
 204 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 205 {
 206          int    i;
 207          int    free = -1;
 208          int    oldest = 0;
 209
 210         // Find an entry for the MAC address in the cache
 211         Mutex_Acquire(&glARP_Cache6);
 212         for( i = giARP_Cache6Space; i--; )
 213         {
 214                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 215                         oldest = i;
 216                 }
 217                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 218                 if( gaARP_Cache6[i].LastUpdate == 0 && free == -1 )     free = i;
 219         }
 220         // If there was no match, we need to make one
 221         if(i == -1) {
 222                 if(free != -1)
 223                         i = free;
 224                 else
 225                         i = oldest;
 226                 gaARP_Cache6[i].MAC = HWAddr;
 227         }
 228
 229         gaARP_Cache6[i].IP = SWAddr;
 230         gaARP_Cache6[i].LastUpdate = now();
 231         giARP_LastUpdateID ++;
 232         Mutex_Release(&glARP_Cache6);
 233 }
 234 #endif
 235
 236 /**
 237  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 238  * \brief Called when an ARP packet is recieved
 239  */
 240 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 241 {
 242         tArpRequest4    *req4 = Buffer;
 243         #if ARPv6
 244         tArpRequest6    *req6 = Buffer;
 245         #endif
 246         tInterface      *iface;
 247
 248         // Sanity Check Packet
 249         if( Length < (int)sizeof(tArpRequest4) ) {
 250                 Log_Log("ARP", "Recieved undersized packet");
 251                 return ;
 252         }
 253         if( ntohs(req4->Type) != 0x0800 ) {
 254                 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
 255                 return ;
 256         }
 257         if( req4->HWSize != 6 ) {
 258                 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 259                 return;
 260         }
 261         #if ARP_DETECT_SPOOFS
 262         if( !MAC_EQU(req4->SourceMac, From) ) {
 263                 Log_Log("ARP", "ARP spoofing detected "
 264                         "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
 265                         req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
 266                         req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
 267                         From.B[0], From.B[1], From.B[2],
 268                         From.B[3], From.B[4], From.B[5]
 269                         );
 270                 return;
 271         }
 272         #endif
 273
 274         switch( ntohs(req4->Request) )
 275         {
 276         case 1: // You want my IP?
 277                 // Check what type of IP it is
 278                 switch( req4->SWSize )
 279                 {
 280                 case 4:
 281                         Log_Debug("ARP", "ARP Request IPv4 Address %i.%i.%i.%i from %i.%i.%i.%i",
 282                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 283                                 req4->DestIP.B[3],
 284                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 285                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 286                         Log_Debug("ARP", " from MAC %02x:%02x:%02x:%02x:%02x:%02x",
 287                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 288                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 289                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 290                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 291                         if( iface )
 292                         {
 293                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 294
 295                                 req4->DestIP = req4->SourceIP;
 296                                 req4->DestMac = req4->SourceMac;
 297                                 req4->SourceIP = *(tIPv4*)iface->Address;;
 298                                 req4->SourceMac = Adapter->MacAddr;
 299                                 req4->Request = htons(2);
 300                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 301                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 302                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 303                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 304                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 305                         }
 306                         break;
 307                 #if ARPv6
 308                 case 6:
 309                         if( Length < (int)sizeof(tArpRequest6) ) {
 310                                 Log_Log("ARP", "Recieved undersized packet (IPv6)");
 311                                 return ;
 312                         }
 313                         Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
 314                                 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
 315                                 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
 316                                 );
 317                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 318                         if( iface )
 319                         {
 320                                 req6->DestIP = req6->SourceIP;
 321                                 req6->DestMac = req6->SourceMac;
 322                                 req6->SourceIP = *(tIPv6*)iface->Address;
 323                                 req6->SourceMac = Adapter->MacAddr;
 324                                 req6->Request = htons(2);
 325                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 326                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 327                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 328                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 329                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 330                         }
 331                         break;
 332                 #endif
 333                 default:
 334                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 335                         return ;
 336                 }
 337
 338                 break;
 339
 340         case 2: // Ooh! A response!
 341                 // Check what type of IP it is
 342                 switch( req4->SWSize )
 343                 {
 344                 case 4:
 345                         ARP_UpdateCache4( req4->SourceIP, From );
 346                         break;
 347                 #if ARPv6
 348                 case 6:
 349                         if( Length < (int)sizeof(tArpRequest6) ) {
 350                                 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
 351                                 return ;
 352                         }
 353                         ARP_UpdateCache6( req6->SourceIP, From );
 354                         break;
 355                 #endif
 356                 default:
 357                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 358                         return ;
 359                 }
 360
 361                 break;
 362
 363         default:
 364                 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));
 365                 break;
 366         }
 367 }