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( route ) {
  85                         // If the next hop is defined, use it
  86                         // - 0.0.0.0 as the next hop means "no next hop / direct"
  87                         if( ((tIPv4*)route->NextHop)->L != 0 ) {
  88                                 // Recursion: see /Recursion/
  89                                 return ARP_Resolve4(Interface, *(tIPv4*)route->NextHop);
  90                         }
  91                 }
  92         }
  93
  94         // Check ARP Cache
  95         Mutex_Acquire( &glARP_Cache4 );
  96         for( i = 0; i < giARP_Cache4Space; i++ )
  97         {
  98                 if(gaARP_Cache4[i].IP.L != Address.L)   continue;
  99
 100                 // Check if the entry needs to be refreshed
 101                 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE )  break;
 102
 103                 Mutex_Release( &glARP_Cache4 );
 104                 LOG("Return %x:%x:%x:%x:%x:%x",
 105                         gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
 106                         gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
 107                         gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
 108                         );
 109                 LEAVE('-');
 110                 return gaARP_Cache4[i].MAC;
 111         }
 112         Mutex_Release( &glARP_Cache4 );
 113
 114         lastID = giARP_LastUpdateID;
 115
 116         // Create request
 117         Log_Log("ARP4", "Asking for address %i.%i.%i.%i",
 118                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]
 119                 );
 120         req.HWType = htons(0x0001);     // Ethernet
 121         req.Type   = htons(0x0800);
 122         req.HWSize = 6;
 123         req.SWSize = 4;
 124         req.Request = htons(1);
 125         req.SourceMac = Interface->Adapter->MacAddr;
 126         req.SourceIP = *(tIPv4*)Interface->Address;
 127         req.DestMac = cMAC_BROADCAST;
 128         req.DestIP = Address;
 129
 130         // Send Request
 131         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
 132
 133         timeout = now() + Interface->TimeoutDelay;
 134
 135         // Wait for a reply
 136         for(;;)
 137         {
 138                 while(lastID == giARP_LastUpdateID && now() < timeout)
 139                         Threads_Yield();
 140
 141                 if( now() >= timeout )  break;  // Timeout
 142
 143                 lastID = giARP_LastUpdateID;
 144
 145                 Mutex_Acquire( &glARP_Cache4 );
 146                 for( i = 0; i < giARP_Cache4Space; i++ )
 147                 {
 148                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 149
 150                         Mutex_Release( &glARP_Cache4 );
 151                         return gaARP_Cache4[i].MAC;
 152                 }
 153                 Mutex_Release( &glARP_Cache4 );
 154         }
 155         {
 156                 tMacAddr        ret = {{0,0,0,0,0,0}};
 157                 return ret;
 158         }
 159 }
 160
 161 /**
 162  * \brief Updates the ARP Cache entry for an IPv4 Address
 163  */
 164 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 165 {
 166          int    i;
 167          int    free = -1;
 168          int    oldest = 0;
 169
 170         // Find an entry for the IP address in the cache
 171         Mutex_Acquire(&glARP_Cache4);
 172         for( i = giARP_Cache4Space; i--; )
 173         {
 174                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 175                         oldest = i;
 176                 }
 177                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 178                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 179         }
 180         // If there was no match, we need to make one
 181         if(i == -1) {
 182                 if(free != -1)
 183                         i = free;
 184                 else
 185                         i = oldest;
 186                 gaARP_Cache4[i].IP = SWAddr;
 187         }
 188
 189         Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
 190                 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
 191                 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
 192                 i
 193                 );
 194
 195         gaARP_Cache4[i].MAC = HWAddr;
 196         gaARP_Cache4[i].LastUpdate = now();
 197         giARP_LastUpdateID ++;
 198         Mutex_Release(&glARP_Cache4);
 199 }
 200
 201 #if ARPv6
 202 /**
 203  * \brief Updates the ARP Cache entry for an IPv6 Address
 204  */
 205 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 206 {
 207          int    i;
 208          int    free = -1;
 209          int    oldest = 0;
 210
 211         // Find an entry for the MAC address in the cache
 212         Mutex_Acquire(&glARP_Cache6);
 213         for( i = giARP_Cache6Space; i--; )
 214         {
 215                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 216                         oldest = i;
 217                 }
 218                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 219                 if( gaARP_Cache6[i].LastUpdate == 0 && free == -1 )     free = i;
 220         }
 221         // If there was no match, we need to make one
 222         if(i == -1) {
 223                 if(free != -1)
 224                         i = free;
 225                 else
 226                         i = oldest;
 227                 gaARP_Cache6[i].MAC = HWAddr;
 228         }
 229
 230         gaARP_Cache6[i].IP = SWAddr;
 231         gaARP_Cache6[i].LastUpdate = now();
 232         giARP_LastUpdateID ++;
 233         Mutex_Release(&glARP_Cache6);
 234 }
 235 #endif
 236
 237 /**
 238  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 239  * \brief Called when an ARP packet is recieved
 240  */
 241 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 242 {
 243         tArpRequest4    *req4 = Buffer;
 244         #if ARPv6
 245         tArpRequest6    *req6 = Buffer;
 246         #endif
 247         tInterface      *iface;
 248
 249         // Sanity Check Packet
 250         if( Length < (int)sizeof(tArpRequest4) ) {
 251                 Log_Log("ARP", "Recieved undersized packet");
 252                 return ;
 253         }
 254         if( ntohs(req4->Type) != 0x0800 ) {
 255                 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
 256                 return ;
 257         }
 258         if( req4->HWSize != 6 ) {
 259                 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 260                 return;
 261         }
 262         #if ARP_DETECT_SPOOFS
 263         if( !MAC_EQU(req4->SourceMac, From) ) {
 264                 Log_Log("ARP", "ARP spoofing detected "
 265                         "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
 266                         req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
 267                         req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
 268                         From.B[0], From.B[1], From.B[2],
 269                         From.B[3], From.B[4], From.B[5]
 270                         );
 271                 return;
 272         }
 273         #endif
 274
 275         Log_Debug("ARP", "Request ID %i", ntohs(req4->Request));
 276
 277         switch( ntohs(req4->Request) )
 278         {
 279         case 1: // You want my IP?
 280                 Log_Debug("ARP", "ARP Request Address class %i", req4->SWSize);
 281                 // Check what type of IP it is
 282                 switch( req4->SWSize )
 283                 {
 284                 case 4:
 285                         Log_Debug("ARP", "From MAC %02x:%02x:%02x:%02x:%02x:%02x",
 286                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 287                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 288                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 289                         //Log_Debug("ARP", "to MAC %02x:%02x:%02x:%02x:%02x:%02x",
 290                         //      req4->DestMac.B[0], req4->DestMac.B[1],
 291                         //      req4->DestMac.B[2], req4->DestMac.B[3],
 292                         //      req4->DestMac.B[4], req4->DestMac.B[5]);
 293                         Log_Debug("ARP", "ARP Request IPv4 Address %i.%i.%i.%i from %i.%i.%i.%i",
 294                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 295                                 req4->DestIP.B[3],
 296                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 297                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 298                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 299                         if( iface )
 300                         {
 301                                 Log_Debug("ARP", "Caching sender's IP Address");
 302                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 303
 304                                 req4->DestIP = req4->SourceIP;
 305                                 req4->DestMac = req4->SourceMac;
 306                                 req4->SourceIP = *(tIPv4*)iface->Address;;
 307                                 req4->SourceMac = Adapter->MacAddr;
 308                                 req4->Request = htons(2);
 309                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 310                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 311                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 312                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 313                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 314                         }
 315                         break;
 316                 #if ARPv6
 317                 case 6:
 318                         if( Length < (int)sizeof(tArpRequest6) ) {
 319                                 Log_Log("ARP", "Recieved undersized packet (IPv6)");
 320                                 return ;
 321                         }
 322                         Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
 323                                 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
 324                                 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
 325                                 );
 326                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 327                         if( iface )
 328                         {
 329                                 req6->DestIP = req6->SourceIP;
 330                                 req6->DestMac = req6->SourceMac;
 331                                 req6->SourceIP = *(tIPv6*)iface->Address;
 332                                 req6->SourceMac = Adapter->MacAddr;
 333                                 req6->Request = htons(2);
 334                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 335                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 336                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 337                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 338                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 339                         }
 340                         break;
 341                 #endif
 342                 default:
 343                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 344                         return ;
 345                 }
 346
 347                 break;
 348
 349         case 2: // Ooh! A response!
 350                 // Check what type of IP it is
 351                 switch( req4->SWSize )
 352                 {
 353                 case 4:
 354                         ARP_UpdateCache4( req4->SourceIP, From );
 355                         break;
 356                 #if ARPv6
 357                 case 6:
 358                         if( Length < (int)sizeof(tArpRequest6) ) {
 359                                 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
 360                                 return ;
 361                         }
 362                         ARP_UpdateCache6( req6->SourceIP, From );
 363                         break;
 364                 #endif
 365                 default:
 366                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 367                         return ;
 368                 }
 369
 370                 break;
 371
 372         default:
 373                 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));
 374                 break;
 375         }
 376 }