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
  80         {
  81                 tRoute  *route = IPStack_FindRoute(4, Interface, &Address);
  82                 if( route ) {
  83                         // If the next hop is defined, use it
  84                         // - 0.0.0.0 as the next hop means "no next hop / direct"
  85                         if( ((tIPv4*)route->NextHop)->L != 0 ) {
  86                                 // Recursion: see /Recursion/
  87                                 return ARP_Resolve4(Interface, *(tIPv4*)route->NextHop);
  88                         }
  89                 }
  90         }
  91
  92         // Check ARP Cache
  93         Mutex_Acquire( &glARP_Cache4 );
  94         for( i = 0; i < giARP_Cache4Space; i++ )
  95         {
  96                 if(gaARP_Cache4[i].IP.L != Address.L)   continue;
  97
  98                 // Check if the entry needs to be refreshed
  99                 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE )  break;
 100
 101                 Mutex_Release( &glARP_Cache4 );
 102                 LOG("Return %x:%x:%x:%x:%x:%x",
 103                         gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
 104                         gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
 105                         gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
 106                         );
 107                 LEAVE('-');
 108                 return gaARP_Cache4[i].MAC;
 109         }
 110         Mutex_Release( &glARP_Cache4 );
 111
 112         lastID = giARP_LastUpdateID;
 113
 114         // Create request
 115         Log_Log("ARP4", "Asking for address %i.%i.%i.%i",
 116                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]
 117                 );
 118         req.HWType = htons(0x0001);     // Ethernet
 119         req.Type   = htons(0x0800);
 120         req.HWSize = 6;
 121         req.SWSize = 4;
 122         req.Request = htons(1);
 123         req.SourceMac = Interface->Adapter->MacAddr;
 124         req.SourceIP = *(tIPv4*)Interface->Address;
 125         req.DestMac = cMAC_BROADCAST;
 126         req.DestIP = Address;
 127
 128         // Send Request
 129         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
 130
 131         // Wait for a reply
 132         for(;;)
 133         {
 134                 while(lastID == giARP_LastUpdateID)     Threads_Yield();
 135                 lastID = giARP_LastUpdateID;
 136
 137                 Mutex_Acquire( &glARP_Cache4 );
 138                 for( i = 0; i < giARP_Cache4Space; i++ )
 139                 {
 140                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 141
 142                         Mutex_Release( &glARP_Cache4 );
 143                         return gaARP_Cache4[i].MAC;
 144                 }
 145                 Mutex_Release( &glARP_Cache4 );
 146         }
 147 }
 148
 149 /**
 150  * \brief Updates the ARP Cache entry for an IPv4 Address
 151  */
 152 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 153 {
 154          int    i;
 155          int    free = -1;
 156          int    oldest = 0;
 157
 158         // Find an entry for the IP address in the cache
 159         Mutex_Acquire(&glARP_Cache4);
 160         for( i = giARP_Cache4Space; i--; )
 161         {
 162                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 163                         oldest = i;
 164                 }
 165                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 166                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 167         }
 168         // If there was no match, we need to make one
 169         if(i == -1) {
 170                 if(free != -1)
 171                         i = free;
 172                 else
 173                         i = oldest;
 174                 gaARP_Cache4[i].IP = SWAddr;
 175         }
 176
 177         Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
 178                 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
 179                 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
 180                 i
 181                 );
 182
 183         gaARP_Cache4[i].MAC = HWAddr;
 184         gaARP_Cache4[i].LastUpdate = now();
 185         giARP_LastUpdateID ++;
 186         Mutex_Release(&glARP_Cache4);
 187 }
 188
 189 #if ARPv6
 190 /**
 191  * \brief Updates the ARP Cache entry for an IPv6 Address
 192  */
 193 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 194 {
 195          int    i;
 196          int    free = -1;
 197          int    oldest = 0;
 198
 199         // Find an entry for the MAC address in the cache
 200         Mutex_Acquire(&glARP_Cache6);
 201         for( i = giARP_Cache6Space; i--; )
 202         {
 203                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 204                         oldest = i;
 205                 }
 206                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 207                 if( gaARP_Cache6[i].LastUpdate == 0 && free == -1 )     free = i;
 208         }
 209         // If there was no match, we need to make one
 210         if(i == -1) {
 211                 if(free != -1)
 212                         i = free;
 213                 else
 214                         i = oldest;
 215                 gaARP_Cache6[i].MAC = HWAddr;
 216         }
 217
 218         gaARP_Cache6[i].IP = SWAddr;
 219         gaARP_Cache6[i].LastUpdate = now();
 220         giARP_LastUpdateID ++;
 221         Mutex_Release(&glARP_Cache6);
 222 }
 223 #endif
 224
 225 /**
 226  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 227  * \brief Called when an ARP packet is recieved
 228  */
 229 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 230 {
 231         tArpRequest4    *req4 = Buffer;
 232         #if ARPv6
 233         tArpRequest6    *req6 = Buffer;
 234         #endif
 235         tInterface      *iface;
 236
 237         // Sanity Check Packet
 238         if( Length < (int)sizeof(tArpRequest4) ) {
 239                 Log_Log("ARP", "Recieved undersized packet");
 240                 return ;
 241         }
 242         if( ntohs(req4->Type) != 0x0800 ) {
 243                 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
 244                 return ;
 245         }
 246         if( req4->HWSize != 6 ) {
 247                 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 248                 return;
 249         }
 250         #if ARP_DETECT_SPOOFS
 251         if( !MAC_EQU(req4->SourceMac, From) ) {
 252                 Log_Log("ARP", "ARP spoofing detected "
 253                         "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
 254                         req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
 255                         req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
 256                         From.B[0], From.B[1], From.B[2],
 257                         From.B[3], From.B[4], From.B[5]
 258                         );
 259                 return;
 260         }
 261         #endif
 262
 263         Log_Debug("ARP", "Request ID %i", ntohs(req4->Request));
 264
 265         switch( ntohs(req4->Request) )
 266         {
 267         case 1: // You want my IP?
 268                 Log_Debug("ARP", "ARP Request Address class %i", req4->SWSize);
 269                 // Check what type of IP it is
 270                 switch( req4->SWSize )
 271                 {
 272                 case 4:
 273                         Log_Debug("ARP", "From MAC %02x:%02x:%02x:%02x:%02x:%02x",
 274                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 275                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 276                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 277                         //Log_Debug("ARP", "to MAC %02x:%02x:%02x:%02x:%02x:%02x",
 278                         //      req4->DestMac.B[0], req4->DestMac.B[1],
 279                         //      req4->DestMac.B[2], req4->DestMac.B[3],
 280                         //      req4->DestMac.B[4], req4->DestMac.B[5]);
 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                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 287                         if( iface )
 288                         {
 289                                 Log_Debug("ARP", "Caching sender's IP Address");
 290                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 291
 292                                 req4->DestIP = req4->SourceIP;
 293                                 req4->DestMac = req4->SourceMac;
 294                                 req4->SourceIP = *(tIPv4*)iface->Address;;
 295                                 req4->SourceMac = Adapter->MacAddr;
 296                                 req4->Request = htons(2);
 297                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 298                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 299                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 300                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 301                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 302                         }
 303                         break;
 304                 #if ARPv6
 305                 case 6:
 306                         if( Length < (int)sizeof(tArpRequest6) ) {
 307                                 Log_Log("ARP", "Recieved undersized packet (IPv6)");
 308                                 return ;
 309                         }
 310                         Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
 311                                 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
 312                                 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
 313                                 );
 314                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 315                         if( iface )
 316                         {
 317                                 req6->DestIP = req6->SourceIP;
 318                                 req6->DestMac = req6->SourceMac;
 319                                 req6->SourceIP = *(tIPv6*)iface->Address;
 320                                 req6->SourceMac = Adapter->MacAddr;
 321                                 req6->Request = htons(2);
 322                                 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
 323                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 324                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 325                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 326                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 327                         }
 328                         break;
 329                 #endif
 330                 default:
 331                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 332                         return ;
 333                 }
 334
 335                 break;
 336
 337         case 2: // Ooh! A response!
 338                 // Check what type of IP it is
 339                 switch( req4->SWSize )
 340                 {
 341                 case 4:
 342                         ARP_UpdateCache4( req4->SourceIP, From );
 343                         break;
 344                 #if ARPv6
 345                 case 6:
 346                         if( Length < (int)sizeof(tArpRequest6) ) {
 347                                 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
 348                                 return ;
 349                         }
 350                         ARP_UpdateCache6( req6->SourceIP, From );
 351                         break;
 352                 #endif
 353                 default:
 354                         Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
 355                         return ;
 356                 }
 357
 358                 break;
 359
 360         default:
 361                 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));
 362                 break;
 363         }
 364 }