Modules/IPStack/arp.c

   1 /*
   2  * Acess2 IP Stack
   3  * - Address Resolution Protocol
   4  */
   5 #include "ipstack.h"
   6 #include "arp.h"
   7 #include "link.h"
   8
   9 #define ARP_CACHE_SIZE  64
  10
  11 // === IMPORTS ===
  12 extern tInterface       *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  13 extern tInterface       *IPv6_GetInterface(tAdapter *Adapter, tIPv6 Address, int Broadcast);
  14
  15 // === PROTOTYPES ===
  16  int    ARP_Initialise();
  17  int    ARP_int_Resolve4(tInterface *Interface, tIPv4 Address);
  18 void    ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer);
  19
  20 // === GLOBALS ===
  21 struct sARP_Cache {
  22         tMacAddr        MAC;
  23         tIPv4   IP4;
  24         tIPv6   IP6;
  25         Sint64  LastUpdate;
  26 }       *gaARP_Cache;
  27  int    giARP_CacheSpace;
  28
  29 // === CODE ===
  30 /**
  31  * \fn int ARP_Initialise()
  32  * \brief Initalise the ARP section
  33  */
  34 int ARP_Initialise()
  35 {
  36         gaARP_Cache = malloc( ARP_CACHE_SIZE * sizeof(*gaARP_Cache) );
  37         memset( gaARP_Cache, 0, ARP_CACHE_SIZE * sizeof(*gaARP_Cache) );
  38         giARP_CacheSpace = ARP_CACHE_SIZE;
  39
  40         Link_RegisterType(0x0806, ARP_int_GetPacket);
  41         return 1;
  42 }
  43
  44 /**
  45  * \fn int ARP_int_Resolve4(tInterface *Interface, tIPv4 Address)
  46  * \brief Request the network to resolve an IPv4 Address
  47  * \return Boolean Success
  48  */
  49 int ARP_int_Resolve4(tInterface *Interface, tIPv4 Address)
  50 {
  51         struct sArpRequest4     req;
  52
  53         req.HWType = htons(0x100);      // Ethernet
  54         req.Type   = htons(0x0800);
  55         req.HWSize = 6;
  56         req.SWSize = 4;
  57         req.Request = htons(1);
  58         req.SourceMac = Interface->Adapter->MacAddr;
  59         req.SourceIP = Interface->IP4.Address;
  60         req.DestMac = cMAC_BROADCAST;
  61         req.DestIP = Address;
  62
  63         Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
  64
  65         return 0;
  66 }
  67
  68 /**
  69  * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  70  * \brief Called when an ARP packet is recieved
  71  */
  72 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  73 {
  74          int    i, free = -1;
  75          int    oldest = 0;
  76         tArpRequest4    *req4 = Buffer;
  77         tArpRequest6    *req6 = Buffer;
  78         tInterface      *iface;
  79
  80         // Sanity Check Packet
  81         if( Length < sizeof(tArpRequest4) ) {
  82                 Log("[ARP  ] Recieved undersized packet");
  83                 return ;
  84         }
  85         if( ntohs(req4->Type) != 0x0800 ) {
  86                 Log("[ARP  ] Recieved a packet with a bad type 0x%x", ntohs(req4->Type));
  87                 return ;
  88         }
  89         if( req4->HWSize != 6 ) {
  90                 Log("[ARP  ] Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
  91                 return;
  92         }
  93         if( !MAC_EQU(req4->SourceMac, From) ) {
  94                 Log("[ARP  ] ARP spoofing detected", req4->HWSize);
  95                 return;
  96         }
  97
  98         Log("[ARP  ] Request ID %i", ntohs(req4->Request));
  99
 100         switch( ntohs(req4->Request) )
 101         {
 102         case 1: // You want my IP?
 103                 Log("[ARP  ] ARP Request Address class %i", req4->SWSize);
 104                 // Check what type of IP it is
 105                 switch( req4->SWSize )
 106                 {
 107                 case 4:
 108                         Log("[ARP  ] From MAC %02x:%02x:%02x:%02x:%02x:%02x",
 109                                 req4->SourceMac.B[0], req4->SourceMac.B[1],
 110                                 req4->SourceMac.B[2], req4->SourceMac.B[3],
 111                                 req4->SourceMac.B[4], req4->SourceMac.B[5]);
 112                         Log("[ARP  ] to MAC %02x:%02x:%02x:%02x:%02x:%02x",
 113                                 req4->DestMac.B[0], req4->DestMac.B[1],
 114                                 req4->DestMac.B[2], req4->DestMac.B[3],
 115                                 req4->DestMac.B[4], req4->DestMac.B[5]);
 116                         Log("[ARP  ] ARP Request IPv4 Address %i.%i.%i.%i",
 117                                 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
 118                                 req4->DestIP.B[3]);
 119                         Log("[ARP  ] from %i.%i.%i.%i",
 120                                 req4->SourceIP.B[0], req4->SourceIP.B[1],
 121                                 req4->SourceIP.B[2], req4->SourceIP.B[3]);
 122                         iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
 123                         if( iface )
 124                         {
 125                                 req4->DestIP = req4->SourceIP;
 126                                 req4->DestMac = req4->SourceMac;
 127                                 req4->SourceIP = iface->IP4.Address;
 128                                 req4->SourceMac = Adapter->MacAddr;
 129                                 req4->Request = htons(2);
 130                                 Log("[ARP  ] Hey, That's us!");
 131                                 Log("[ARP  ] Sending back %02x:%02x:%02x:%02x:%02x:%02x",
 132                                         req4->SourceMac.B[0], req4->SourceMac.B[1],
 133                                         req4->SourceMac.B[2], req4->SourceMac.B[3],
 134                                         req4->SourceMac.B[4], req4->SourceMac.B[5]);
 135                                 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
 136                         }
 137                         break;
 138                 case 6:
 139                         if( Length < sizeof(tArpRequest6) ) {
 140                                 Log("[ARP  ] Recieved undersized packet (IPv6)");
 141                                 return ;
 142                         }
 143                         iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
 144                         if( iface )
 145                         {
 146                                 req6->DestIP = req6->SourceIP;
 147                                 req6->DestMac = req6->SourceMac;
 148                                 req6->SourceIP = iface->IP6.Address;
 149                                 req6->SourceMac = Adapter->MacAddr;
 150                                 req6->Request = htons(2);
 151                                 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
 152                         }
 153                         break;
 154                 default:
 155                         Log("[ARP  ] Unknown Protocol Address size (%i)", req4->SWSize);
 156                         return ;
 157                 }
 158
 159                 break;
 160
 161         case 2: // Ooh! A response!
 162                 // Find an entry for the MAC address in the cache
 163                 for( i = giARP_CacheSpace; i--; )
 164                 {
 165                         if(gaARP_Cache[oldest].LastUpdate > gaARP_Cache[i].LastUpdate) {
 166                                 oldest = i;
 167                         }
 168                         if( MAC_EQU(gaARP_Cache[i].MAC, From) ) break;
 169                         if( gaARP_Cache[i].LastUpdate == 0 && free==-1 )        free = i;
 170                 }
 171                 if(i + 1 == 0) {
 172                         if(free != -1)
 173                                 i = free;
 174                         else
 175                                 i = oldest;
 176                 }
 177
 178                 // Check what type of IP it is
 179                 switch( req4->SWSize )
 180                 {
 181                 case 4:
 182                         gaARP_Cache[i].IP4 = req4->SourceIP;
 183                         break;
 184                 case 6:
 185                         if( Length < sizeof(tArpRequest6) ) {
 186                                 Log("[ARP  ] Recieved undersized packet (IPv6)");
 187                                 return ;
 188                         }
 189                         gaARP_Cache[i].IP6 = req6->SourceIP;
 190                         break;
 191                 default:
 192                         Log("[ARP  ] Unknown Protocol Address size (%i)", req4->SWSize);
 193                         return ;
 194                 }
 195
 196                 gaARP_Cache[i].LastUpdate = now();
 197                 break;
 198         }
 199 }