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 tMacAddr        ARP_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         struct sArpRequest4     req;
  68
  69         ENTER("pInterface xAddress", Interface, Address);
  70
  71         LOCK( &glARP_Cache4 );
  72         for( i = 0; i < giARP_Cache4Space; i++ )
  73         {
  74                 if(gaARP_Cache4[i].IP.L != Address.L)   continue;
  75
  76                 // Check if the entry needs to be refreshed
  77                 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE )  break;
  78
  79                 RELEASE( &glARP_Cache4 );
  80                 LOG("Return %x:%x:%x:%x:%x:%x",
  81                         gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
  82                         gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
  83                         gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
  84                         );
  85                 LEAVE('-');
  86                 return gaARP_Cache4[i].MAC;
  87         }
  88         RELEASE( &glARP_Cache4 );
  89
  90         lastID = giARP_LastUpdateID;
  91
  92         // Create request
  93         Log("[ARP4 ] Asking for address %i.%i.%i.%i",
  94                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]
  95                 );
  96         req.HWType = htons(1);  // Ethernet
  97         req.Type   = htons(0x0800);
  98         req.HWSize = 6;
  99         req.SWSize = 4;
 100         req.Request = htons(1);
 101         req.SourceMac = Interface->Adapter->MacAddr;
 102         req.SourceIP = Interface->IP4.Address;
 103         req.DestMac = cMAC_BROADCAST;
 104         req.DestIP = Address;
 105
 106         // Send Request
 107         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
 108
 109         // Wait for a reply
 110         for(;;)
 111         {
 112                 while(lastID == giARP_LastUpdateID)     Threads_Yield();
 113                 lastID = giARP_LastUpdateID;
 114
 115                 LOCK( &glARP_Cache4 );
 116                 for( i = 0; i < giARP_Cache4Space; i++ )
 117                 {
 118                         if(gaARP_Cache4[i].IP.L != Address.L)   continue;
 119
 120                         RELEASE( &glARP_Cache4 );
 121                         return gaARP_Cache4[i].MAC;
 122                 }
 123                 RELEASE( &glARP_Cache4 );
 124         }
 125 }
 126
 127 /**
 128  * \brief Updates the ARP Cache entry for an IPv4 Address
 129  */
 130 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
 131 {
 132          int    i;
 133          int    free = -1;
 134          int    oldest = 0;
 135
 136         // Find an entry for the IP address in the cache
 137         LOCK(&glARP_Cache4);
 138         for( i = giARP_Cache4Space; i--; )
 139         {
 140                 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
 141                         oldest = i;
 142                 }
 143                 if( gaARP_Cache4[i].IP.L == SWAddr.L )  break;
 144                 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 )     free = i;
 145         }
 146         // If there was no match, we need to make one
 147         if(i == -1) {
 148                 if(free != -1)
 149                         i = free;
 150                 else
 151                         i = oldest;
 152                 gaARP_Cache4[i].IP = SWAddr;
 153         }
 154
 155         gaARP_Cache4[i].MAC = HWAddr;
 156         gaARP_Cache4[i].LastUpdate = now();
 157         RELEASE(&glARP_Cache4);
 158 }
 159
 160 /**
 161  * \brief Updates the ARP Cache entry for an IPv6 Address
 162  */
 163 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
 164 {
 165          int    i;
 166          int    free = -1;
 167          int    oldest = 0;
 168
 169         // Find an entry for the MAC address in the cache
 170         LOCK(&glARP_Cache6);
 171         for( i = giARP_Cache6Space; i--; )
 172         {
 173                 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
 174                         oldest = i;
 175                 }
 176                 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) )      break;
 177                 if( gaARP_Cache6[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_Cache6[i].MAC = HWAddr;
 186         }
 187
 188         gaARP_Cache6[i].IP = SWAddr;
 189         gaARP_Cache6[i].LastUpdate = now();
 190         RELEASE(&glARP_Cache6);
 191 }
 192
 193 /**
 194  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 195  * \brief Called when an ARP packet is recieved
 196  */
 197 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 198 {
 199         tArpRequest4    *req4 = Buffer;
 200         tArpRequest6    *req6 = Buffer;
 201         tInterface      *iface;
 202
 203         // Sanity Check Packet
 204         if( Length < sizeof(tArpRequest4) ) {
 205                 Log("[ARP  ] Recieved undersized packet");
 206                 return ;
 207         }
 208         if( ntohs(req4->Type) != 0x0800 ) {
 209                 Log("[ARP  ] Recieved a packet with a bad type 0x%x", ntohs(req4->Type));
 210                 return ;
 211         }
 212         if( req4->HWSize != 6 ) {
 213                 Log("[ARP  ] Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
 214                 return;
 215         }
 216         if( !MAC_EQU(req4->SourceMac, From) ) {
 217                 Log("[ARP  ] ARP spoofing detected", req4->HWSize);
 218                 return;
 219         }
 220
 221         Log("[ARP  ] Request ID %i", ntohs(req4->Request));
 222
 223         switch( ntohs(req4->Request) )
 224         {
 225         case 1: // You want my IP?
 226                 Log("[ARP  ] ARP Request Address class %i", req4->SWSize);
 227                 // Check what type of IP it is
 228                 switch( req4->SWSize )
 229                 {
 230                 case 4:
 231                         Log("[ARP  ] From MAC %02x:%02x:%02x:%02x:%02x:%02x",
 232                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 233                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 234                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 235                         Log("[ARP  ] to MAC %02x:%02x:%02x:%02x:%02x:%02x",
 236                                 req4->DestMac.B[0], req4->DestMac.B[1],
 237                                 req4->DestMac.B[2], req4->DestMac.B[3],
 238                                 req4->DestMac.B[4], req4->DestMac.B[5]);
 239                         Log("[ARP  ] ARP Request IPv4 Address %i.%i.%i.%i",
 240                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 241                                 req4->DestIP.B[3]);
 242                         Log("[ARP  ] from %i.%i.%i.%i",
 243                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 244                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 245                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 246                         if( iface )
 247                         {
 248                                 Log("[ARP  ] Caching sender's IP Address");
 249                                 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
 250
 251                                 req4->DestIP = req4->SourceIP;
 252                                 req4->DestMac = req4->SourceMac;
 253                                 req4->SourceIP = iface->IP4.Address;
 254                                 req4->SourceMac = Adapter->MacAddr;
 255                                 req4->Request = htons(2);
 256                                 Log("[ARP  ] Hey, That's us!");
 257                                 Log("[ARP  ] Sending back %02x:%02x:%02x:%02x:%02x:%02x",
 258                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 259                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 260                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 261                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 262                         }
 263                         break;
 264                 case 6:
 265                         if( Length < sizeof(tArpRequest6) ) {
 266                                 Log("[ARP  ] Recieved undersized packet (IPv6)");
 267                                 return ;
 268                         }
 269                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 270                         if( iface )
 271                         {
 272                                 req6->DestIP = req6->SourceIP;
 273                                 req6->DestMac = req6->SourceMac;
 274                                 req6->SourceIP = iface->IP6.Address;
 275                                 req6->SourceMac = Adapter->MacAddr;
 276                                 req6->Request = htons(2);
 277                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 278                         }
 279                         break;
 280                 default:
 281                         Log("[ARP  ] Unknown Protocol Address size (%i)", req4->SWSize);
 282                         return ;
 283                 }
 284
 285                 break;
 286
 287         case 2: // Ooh! A response!
 288                 // Check what type of IP it is
 289                 switch( req4->SWSize )
 290                 {
 291                 case 4:
 292                         ARP_UpdateCache4( req4->SourceIP, From );
 293                         break;
 294                 case 6:
 295                         if( Length < sizeof(tArpRequest6) ) {
 296                                 Log("[ARP  ] Recieved undersized packet (IPv6)");
 297                                 return ;
 298                         }
 299                         ARP_UpdateCache6( req6->SourceIP, From );
 300                         break;
 301                 default:
 302                         Log("[ARP  ] Unknown Protocol Address size (%i)", req4->SWSize);
 303                         return ;
 304                 }
 305
 306                 break;
 307         }
 308 }