Modules/IPStack/arp.c

   1 /*
   2  * Acess2 IP Stack
   3  * - Address Resolution Protocol
   4  */
   5 #define DEBUG   0
   6 #include "ipstack.h"
   7 #include "arp.h"
   8 #include "link.h"
   9
  10 #define ARP_CACHE_SIZE  64
  11 #define ARP_MAX_AGE             (60*60*1000)    // 1Hr
  12
  13 // === IMPORTS ===
  14 extern tInterface       *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  15 extern tInterface       *IPv6_GetInterface(tAdapter *Adapter, tIPv6 Address, int Broadcast);
  16
  17 // === PROTOTYPES ===
  18  int    ARP_Initialise();
  19  int    ARP_int_Resolve4(tInterface *Interface, tIPv4 Address);
  20 void    ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer);
  21
  22 // === GLOBALS ===
  23 struct sARP_Cache4 {
  24         tIPv4   IP;
  25         tMacAddr        MAC;
  26         Sint64  LastUpdate;
  27         Sint64  LastUsed;
  28 }       *gaARP_Cache4;
  29  int    giARP_Cache4Space;
  30 tSpinlock       glARP_Cache4;
  31 struct sARP_Cache6 {
  32         tIPv6   IP;
  33         tMacAddr        MAC;
  34         Sint64  LastUpdate;
  35         Sint64  LastUsed;
  36 }       *gaARP_Cache6;
  37  int    giARP_Cache6Space;
  38 tSpinlock       glARP_Cache6;
  39  int    giARP_LastUpdateID = 0;
  40
  41 // === CODE ===
  42 /**
  43  * \fn int ARP_Initialise()
  44  * \brief Initalise the ARP section
  45  */
  46 int ARP_Initialise()
  47 {
  48         gaARP_Cache4 = malloc( ARP_CACHE_SIZE * sizeof(struct sARP_Cache4) );
  49         memset( gaARP_Cache4, 0, ARP_CACHE_SIZE * sizeof(struct sARP_Cache4) );
  50         giARP_Cache4Space = ARP_CACHE_SIZE;
  51
  52         gaARP_Cache6 = malloc( ARP_CACHE_SIZE * sizeof(struct sARP_Cache6) );
  53         memset( gaARP_Cache6, 0, ARP_CACHE_SIZE * sizeof(struct sARP_Cache6) );
  54         giARP_Cache6Space = ARP_CACHE_SIZE;
  55
  56         Link_RegisterType(0x0806, ARP_int_GetPacket);
  57         return 1;
  58 }
  59
  60 /**
  61  * \brief Resolves a MAC address from an IPv4 address
  62  */
  63 tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address)
  64 {
  65          int    lastID;
  66          int    i;
  67
  68         ENTER("pInterface xAddress", Interface, Address);
  69
  70         LOCK( &glARP_Cache4 );
  71         for( i = 0; i < giARP_Cache4Space; i++ )
  72         {
  73                 if(gaARP_Cache4[i].IP.L != Address.L)   continue;
  74
  75                 // Check if the entry needs to be refreshed
  76                 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE )  break;
  77
  78                 RELEASE( &glARP_Cache4 );
  79                 LOG("Return %x:%x:%x:%x:%x:%x",
  80                         gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
  81                         gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
  82                         gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
  83                         );
  84                 LEAVE('-');
  85                 return gaARP_Cache4[i].MAC;
  86         }
  87         RELEASE( &glARP_Cache4 );
  88
  89         lastID = giARP_LastUpdateID;
  90         ARP_int_Resolve4(Interface, Address);
  91         for(;;)
  92         {
  93                 while(lastID == giARP_LastUpdateID)     Threads_Yield();
  94                 lastID = giARP_LastUpdateID;
  95
  96                 LOCK( &glARP_Cache4 );
  97                 for( i = 0; i < giARP_Cache4Space; i++ )
  98                 {
  99                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 100
 101                         RELEASE( &glARP_Cache4 );
 102                         return gaARP_Cache4[i].MAC;
 103                 }
 104                 RELEASE( &glARP_Cache4 );
 105         }
 106 }
 107
 108 /**
 109  * \fn int ARP_int_Resolve4(tInterface *Interface, tIPv4 Address)
 110  * \brief Request the network to resolve an IPv4 Address
 111  * \return Boolean Success
 112  */
 113 int ARP_int_Resolve4(tInterface *Interface, tIPv4 Address)
 114 {
 115         struct sArpRequest4     req;
 116
 117         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(0x100);      // 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 = Interface->IP4.Address;
 127         req.DestMac = cMAC_BROADCAST;
 128         req.DestIP = Address;
 129
 130         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
 131
 132         return 0;
 133 }
 134
 135 /**
 136  * \brief Updates the ARP Cache entry for an IPv4 Address
 137  */
 138 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 139 {
 140          int    i;
 141          int    free = -1;
 142          int    oldest = 0;
 143
 144         // Find an entry for the IP address in the cache
 145         LOCK(&glARP_Cache4);
 146         for( i = giARP_Cache4Space; i--; )
 147         {
 148                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 149                         oldest = i;
 150                 }
 151                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 152                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 153         }
 154         // If there was no match, we need to make one
 155         if(i == -1) {
 156                 if(free != -1)
 157                         i = free;
 158                 else
 159                         i = oldest;
 160                 gaARP_Cache4[i].IP = SWAddr;
 161         }
 162
 163         gaARP_Cache4[i].MAC = HWAddr;
 164         gaARP_Cache4[i].LastUpdate = now();
 165         RELEASE(&glARP_Cache4);
 166 }
 167
 168 /**
 169  * \brief Updates the ARP Cache entry for an IPv6 Address
 170  */
 171 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 172 {
 173          int    i;
 174          int    free = -1;
 175          int    oldest = 0;
 176
 177         // Find an entry for the MAC address in the cache
 178         LOCK(&glARP_Cache6);
 179         for( i = giARP_Cache6Space; i--; )
 180         {
 181                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 182                         oldest = i;
 183                 }
 184                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 185                 if( gaARP_Cache6[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                 gaARP_Cache6[i].MAC = HWAddr;
 194         }
 195
 196         gaARP_Cache6[i].IP = SWAddr;
 197         gaARP_Cache6[i].LastUpdate = now();
 198         RELEASE(&glARP_Cache6);
 199 }
 200
 201 /**
 202  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 203  * \brief Called when an ARP packet is recieved
 204  */
 205 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 206 {
 207         tArpRequest4    *req4 = Buffer;
 208         tArpRequest6    *req6 = Buffer;
 209         tInterface      *iface;
 210
 211         // Sanity Check Packet
 212         if( Length < sizeof(tArpRequest4) ) {
 213                 Log("[ARP  ] Recieved undersized packet");
 214                 return ;
 215         }
 216         if( ntohs(req4->Type) != 0x0800 ) {
 217                 Log("[ARP  ] Recieved a packet with a bad type 0x%x", ntohs(req4->Type));
 218                 return ;
 219         }
 220         if( req4->HWSize != 6 ) {
 221                 Log("[ARP  ] Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 222                 return;
 223         }
 224         if( !MAC_EQU(req4->SourceMac, From) ) {
 225                 Log("[ARP  ] ARP spoofing detected", req4->HWSize);
 226                 return;
 227         }
 228
 229         Log("[ARP  ] Request ID %i", ntohs(req4->Request));
 230
 231         switch( ntohs(req4->Request) )
 232         {
 233         case 1: // You want my IP?
 234                 Log("[ARP  ] ARP Request Address class %i", req4->SWSize);
 235                 // Check what type of IP it is
 236                 switch( req4->SWSize )
 237                 {
 238                 case 4:
 239                         Log("[ARP  ] From MAC %02x:%02x:%02x:%02x:%02x:%02x",
 240                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 241                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 242                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 243                         Log("[ARP  ] to MAC %02x:%02x:%02x:%02x:%02x:%02x",
 244                                 req4->DestMac.B[0], req4->DestMac.B[1],
 245                                 req4->DestMac.B[2], req4->DestMac.B[3],
 246                                 req4->DestMac.B[4], req4->DestMac.B[5]);
 247                         Log("[ARP  ] ARP Request IPv4 Address %i.%i.%i.%i",
 248                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 249                                 req4->DestIP.B[3]);
 250                         Log("[ARP  ] from %i.%i.%i.%i",
 251                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 252                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 253                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 254                         if( iface )
 255                         {
 256                                 Log("[ARP  ] Caching sender's IP Address");
 257                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 258
 259                                 req4->DestIP = req4->SourceIP;
 260                                 req4->DestMac = req4->SourceMac;
 261                                 req4->SourceIP = iface->IP4.Address;
 262                                 req4->SourceMac = Adapter->MacAddr;
 263                                 req4->Request = htons(2);
 264                                 Log("[ARP  ] Hey, That's us!");
 265                                 Log("[ARP  ] Sending back %02x:%02x:%02x:%02x:%02x:%02x",
 266                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 267                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 268                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 269                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 270                         }
 271                         break;
 272                 case 6:
 273                         if( Length < sizeof(tArpRequest6) ) {
 274                                 Log("[ARP  ] Recieved undersized packet (IPv6)");
 275                                 return ;
 276                         }
 277                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 278                         if( iface )
 279                         {
 280                                 req6->DestIP = req6->SourceIP;
 281                                 req6->DestMac = req6->SourceMac;
 282                                 req6->SourceIP = iface->IP6.Address;
 283                                 req6->SourceMac = Adapter->MacAddr;
 284                                 req6->Request = htons(2);
 285                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 286                         }
 287                         break;
 288                 default:
 289                         Log("[ARP  ] Unknown Protocol Address size (%i)", req4->SWSize);
 290                         return ;
 291                 }
 292
 293                 break;
 294
 295         case 2: // Ooh! A response!
 296                 // Check what type of IP it is
 297                 switch( req4->SWSize )
 298                 {
 299                 case 4:
 300                         ARP_UpdateCache4( req4->SourceIP, From );
 301                         break;
 302                 case 6:
 303                         if( Length < sizeof(tArpRequest6) ) {
 304                                 Log("[ARP  ] Recieved undersized packet (IPv6)");
 305                                 return ;
 306                         }
 307                         ARP_UpdateCache6( req6->SourceIP, From );
 308                         break;
 309                 default:
 310                         Log("[ARP  ] Unknown Protocol Address size (%i)", req4->SWSize);
 311                         return ;
 312                 }
 313
 314                 break;
 315         }
 316 }