Modules/IPStack/ipv4.c

   1 /*
   2  * Acess2 IP Stack
   3  * - IPv4 Protcol Handling
   4  */
   5 #include "ipstack.h"
   6 #include "link.h"
   7 #include "ipv4.h"
   8 #include "firewall.h"
   9
  10 #define DEFAULT_TTL     32
  11
  12 // === IMPORTS ===
  13 extern tInterface       *gIP_Interfaces;
  14 extern void     ICMP_Initialise();
  15 extern  int     ICMP_Ping(tInterface *Interface, tIPv4 Addr);
  16 extern tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address);
  17
  18 // === PROTOTYPES ===
  19  int    IPv4_Initialise();
  20  int    IPv4_RegisterCallback(int ID, tIPCallback Callback);
  21 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  22 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  23 Uint32  IPv4_Netmask(int FixedBits);
  24 Uint16  IPv4_Checksum(const void *Buf, int Size);
  25  int    IPv4_Ping(tInterface *Iface, tIPv4 Addr);
  26
  27 // === GLOBALS ===
  28 tIPCallback     gaIPv4_Callbacks[256];
  29
  30 // === CODE ===
  31 /**
  32  * \fn int IPv4_Initialise()
  33  */
  34 int IPv4_Initialise()
  35 {
  36         ICMP_Initialise();
  37         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  38         return 1;
  39 }
  40
  41 /**
  42  * \fn int IPv4_RegisterCallback( int ID, tIPCallback Callback )
  43  * \brief Registers a callback
  44  */
  45 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  46 {
  47         if( ID < 0 || ID > 255 )        return 0;
  48         if( gaIPv4_Callbacks[ID] )      return 0;
  49         gaIPv4_Callbacks[ID] = Callback;
  50         return 1;
  51 }
  52
  53 /**
  54  * \brief Creates and sends an IPv4 Packet
  55  * \param Iface Interface
  56  * \param Address       Destination IP
  57  * \param Protocol      Protocol ID
  58  * \param ID    Some random ID number
  59  * \param Length        Data Length
  60  * \param Data  Packet Data
  61  */
  62 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, const void *Data)
  63 {
  64         tMacAddr        to = ARP_Resolve4(Iface, Address);
  65          int    bufSize = sizeof(tIPv4Header) + Length;
  66         char    buf[bufSize];
  67         tIPv4Header     *hdr = (void*)buf;
  68          int    ret;
  69
  70         // TODO: OUTPUT Firewall rule go here
  71         ret = IPTablesV4_TestChain("OUTPUT",
  72                 &Iface->IP4.Address, &Address,
  73                 Protocol, 0,
  74                 Length, Data);
  75
  76         if(ret != 0)
  77         {
  78                 // Just drop it
  79                 return 0;
  80         }
  81
  82         memcpy(&hdr->Options[0], Data, Length);
  83         hdr->Version = 4;
  84         hdr->HeaderLength = sizeof(tIPv4Header)/4;
  85         hdr->DiffServices = 0;  // TODO: Check
  86
  87         hdr->Reserved = 0;
  88         hdr->DontFragment = 0;
  89         hdr->MoreFragments = 0;
  90         hdr->FragOffLow = 0;
  91         hdr->FragOffHi = 0;
  92
  93         hdr->TotalLength = htons( bufSize );
  94         hdr->Identifcation = htons( ID );       // TODO: Check
  95         hdr->TTL = DEFAULT_TTL;
  96         hdr->Protocol = Protocol;
  97         hdr->HeaderChecksum = 0;        // Will be set later
  98         hdr->Source = Iface->IP4.Address;
  99         hdr->Destination = Address;
 100         hdr->HeaderChecksum = IPv4_Checksum(hdr, sizeof(tIPv4Header));
 101
 102         Log_Log("IPv4", "Sending packet to %i.%i.%i.%i",
 103                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
 104         Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, bufSize, buf);
 105         return 1;
 106 }
 107
 108 /**
 109  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
 110  * \brief Process an IPv4 Packet
 111  */
 112 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 113 {
 114         tIPv4Header     *hdr = Buffer;
 115         tInterface      *iface;
 116         Uint8   *data;
 117          int    dataLength;
 118          int    ret;
 119
 120         if(Length < sizeof(tIPv4Header))        return;
 121
 122         #if 0
 123         //Log_Log("IPv4", "Version = %i", hdr->Version);
 124         //Log_Log("IPv4", "HeaderLength = %i", hdr->HeaderLength);
 125         //Log_Log("IPv4", "DiffServices = %i", hdr->DiffServices);
 126         Log_Log("IPv4", "TotalLength = %i", ntohs(hdr->TotalLength) );
 127         //Log_Log("IPv4", "Identifcation = %i", ntohs(hdr->Identifcation) );
 128         //Log_Log("IPv4", "TTL = %i", hdr->TTL );
 129         Log_Log("IPv4", "Protocol = %i", hdr->Protocol );
 130         //Log_Log("IPv4", "HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
 131         Log_Log("IPv4", "Source = %i.%i.%i.%i",
 132                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
 133         Log_Log("IPv4", "Destination = %i.%i.%i.%i",
 134                 hdr->Destination.B[0], hdr->Destination.B[1],
 135                 hdr->Destination.B[2], hdr->Destination.B[3] );
 136         #endif
 137
 138         // Check that the version IS IPv4
 139         if(hdr->Version != 4) {
 140                 Log_Log("IPv4", "hdr->Version(%i) != 4", hdr->Version);
 141                 return;
 142         }
 143
 144         // Check Header checksum
 145         //TODO
 146
 147         // Check Packet length
 148         if( ntohs(hdr->TotalLength) > Length) {
 149                 Log_Log("IPv4", "hdr->TotalLength(%i) > Length(%i)", ntohs(hdr->TotalLength), Length);
 150                 return;
 151         }
 152
 153
 154         // TODO: Handle packet fragmentation
 155
 156         // Get Data and Data Length
 157         dataLength = ntohs(hdr->TotalLength) - sizeof(tIPv4Header);
 158         data = &hdr->Options[0];
 159
 160         // Get Interface (allowing broadcasts)
 161         iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
 162
 163         // TODO: INPUT Firewall Rule
 164         if( iface ) {
 165                 ret = IPTablesV4_TestChain("INPUT",
 166                         &hdr->Source, &hdr->Destination,
 167                         hdr->Protocol, 0,
 168                         dataLength, data
 169                         );
 170         }
 171         else {
 172                 ret = IPTablesV4_TestChain("FORWARD",
 173                         &hdr->Source, &hdr->Destination,
 174                         hdr->Protocol, 0,
 175                         dataLength, data
 176                         );
 177         }
 178         switch(ret)
 179         {
 180         // 0 - Allow
 181         case 0: break;
 182         // 1 - Silent Drop
 183         case 1: return ;
 184         // Unknown, silent drop
 185         default:
 186                 return ;
 187         }
 188
 189         // Routing
 190         if(!iface)
 191         {
 192                 Log_Log("IPv4", "Route the packet");
 193
 194                 // TODO: Parse Routing tables and determine where to send it
 195
 196                 return ;
 197         }
 198
 199         // Send it on
 200         if( gaIPv4_Callbacks[hdr->Protocol] )
 201                 gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
 202         else
 203                 Log_Log("IPv4", "Unknown Protocol %i", hdr->Protocol);
 204 }
 205
 206 /**
 207  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 208  * \brief Searches an adapter for a matching address
 209  */
 210 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 211 {
 212         tInterface      *iface = NULL;
 213         Uint32  netmask;
 214         Uint32  addr, this;
 215
 216         addr = ntohl( Address.L );
 217
 218         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 219         {
 220                 if( iface->Adapter != Adapter ) continue;
 221                 if( iface->Type != 4 )  continue;
 222                 if( IP4_EQU(Address, iface->IP4.Address) )
 223                         return iface;
 224
 225                 if( !Broadcast )        continue;
 226
 227                 this = ntohl( iface->IP4.Address.L );
 228
 229                 // Check for broadcast
 230                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
 231
 232                 if( (addr & netmask) == (this & netmask)
 233                  && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 234                         return iface;
 235         }
 236         return NULL;
 237 }
 238
 239 /**
 240  * \brief Convert a network prefix to a netmask
 241  *
 242  * For example /24 will become 255.255.255.0
 243  */
 244 Uint32 IPv4_Netmask(int FixedBits)
 245 {
 246         Uint32  ret = 0xFFFFFFFF;
 247         ret >>= (32-FixedBits);
 248         ret <<= (32-FixedBits);
 249         // Returns a native endian netmask
 250         return ret;
 251 }
 252
 253 /**
 254  * \brief Calculate the IPv4 Checksum
 255  */
 256 Uint16 IPv4_Checksum(const void *Buf, int Size)
 257 {
 258         Uint16  sum = 0;
 259         const Uint16    *arr = Buf;
 260          int    i;
 261
 262         Size = (Size + 1) >> 1; // 16-bit word count
 263         for(i = 0; i < Size; i++ )
 264         {
 265                 if((int)sum + arr[i] > 0xFFFF)
 266                         sum ++; // Simulate 1's complement
 267                 sum += arr[i];
 268         }
 269         return ~sum ;
 270 }
 271
 272 /**
 273  * \brief Sends an ICMP Echo and waits for a reply
 274  */
 275 int IPv4_Ping(tInterface *Iface, tIPv4 Addr)
 276 {
 277         return ICMP_Ping(Iface, Addr);
 278 }