KernelLand/Modules/IPStack/ipv4.c

   1 /*
   2  * Acess2 IP Stack
   3  * - IPv4 Protcol Handling
   4  */
   5 #define DEBUG   0
   6 #include "ipstack.h"
   7 #include "link.h"
   8 #include "ipv4.h"
   9 #include "firewall.h"
  10
  11 // === CONSTANTS ===
  12 #define DEFAULT_TTL     32
  13 #define IPV4_TRACE      1       // set to 1 to enable packet tracing
  14
  15 // === IMPORTS ===
  16 extern tInterface       *gIP_Interfaces;
  17 extern void     ICMP_Initialise();
  18 extern  int     ICMP_Ping(tInterface *Interface, tIPv4 Addr);
  19 extern tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address);
  20 extern void     ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr);
  21
  22 // === PROTOTYPES ===
  23  int    IPv4_Initialise();
  24  int    IPv4_RegisterCallback(int ID, tIPCallback Callback);
  25 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  26 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  27 Uint32  IPv4_Netmask(int FixedBits);
  28 Uint16  IPv4_Checksum(const void *Buf, size_t Length);
  29  int    IPv4_Ping(tInterface *Iface, tIPv4 Addr);
  30
  31 // === GLOBALS ===
  32 tIPCallback     gaIPv4_Callbacks[256];
  33
  34 // === CODE ===
  35 /**
  36  * \brief Initialise the IPv4 Code
  37  */
  38 int IPv4_Initialise()
  39 {
  40         ICMP_Initialise();
  41         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  42         return 1;
  43 }
  44
  45 /**
  46  * \brief Registers a callback
  47  * \param ID    8-bit packet type ID
  48  * \param Callback      Callback function
  49  */
  50 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  51 {
  52         if( ID < 0 || ID > 255 )        return 0;
  53         if( gaIPv4_Callbacks[ID] )      return 0;
  54         gaIPv4_Callbacks[ID] = Callback;
  55         return 1;
  56 }
  57
  58 /**
  59  * \brief Creates and sends an IPv4 Packet
  60  * \param Iface Interface
  61  * \param Address       Destination IP
  62  * \param Protocol      Protocol ID
  63  * \param ID    Some random ID number
  64  * \param Length        Data Length
  65  * \param Data  Packet Data
  66  * \return Boolean Success
  67  */
  68 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, tIPStackBuffer *Buffer)
  69 {
  70         tMacAddr        to;
  71         tIPv4Header     hdr;
  72          int    length;
  73
  74         length = IPStack_Buffer_GetLength(Buffer);
  75
  76         // --- Resolve destination MAC address
  77         to = ARP_Resolve4(Iface, Address);
  78         if( MAC_EQU(to, cMAC_ZERO) ) {
  79                 // No route to host
  80                 Log_Notice("IPv4", "No route to host %i.%i.%i.%i",
  81                         Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
  82                 return 0;
  83         }
  84
  85         // --- Handle OUTPUT firewall rules
  86         // TODO: Update firewall rules for tIPStackBuffer
  87         #if 0
  88         int ret = IPTables_TestChain("OUTPUT",
  89                 4, (tIPv4*)Iface->Address, &Address,
  90                 Protocol, 0,
  91                 length, Data);
  92         if(ret > 0) {
  93                 // Just drop it (with an error)
  94                 Log_Notice("IPv4", "Firewall dropped packet");
  95                 return 0;
  96         }
  97         #endif
  98
  99         // --- Initialise header
 100         hdr.Version = 4;
 101         hdr.HeaderLength = sizeof(tIPv4Header)/4;
 102         hdr.DiffServices = 0;   // TODO: Check
 103
 104         hdr.Reserved = 0;
 105         hdr.DontFragment = 0;
 106         hdr.MoreFragments = 0;
 107         hdr.FragOffLow = 0;
 108         hdr.FragOffHi = 0;
 109
 110         hdr.TotalLength = htons( sizeof(tIPv4Header) + length );
 111         hdr.Identifcation = htons( ID );        // TODO: Check
 112         hdr.TTL = DEFAULT_TTL;
 113         hdr.Protocol = Protocol;
 114         hdr.HeaderChecksum = 0; // Will be set later
 115         hdr.Source = *(tIPv4*)Iface->Address;
 116         hdr.Destination = Address;
 117
 118         // Actually set checksum (zeroed above)
 119         hdr.HeaderChecksum = htons( IPv4_Checksum(&hdr, sizeof(tIPv4Header)) );
 120
 121         IPStack_Buffer_AppendSubBuffer(Buffer, sizeof(tIPv4Header), 0, &hdr, NULL, NULL);
 122
 123         #if IPV4_TRACE
 124         Log_Log("IPv4", "Sending packet to %i.%i.%i.%i",
 125                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
 126         #endif
 127         Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, Buffer);
 128         return 1;
 129 }
 130
 131 /**
 132  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
 133  * \brief Process an IPv4 Packet
 134  */
 135 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 136 {
 137         tIPv4Header     *hdr = Buffer;
 138         tInterface      *iface;
 139         Uint8   *data;
 140          int    dataLength;
 141          int    ret;
 142
 143         if(Length < sizeof(tIPv4Header))        return;
 144
 145         #if 0
 146         //Log_Log("IPv4", "Version = %i", hdr->Version);
 147         //Log_Log("IPv4", "HeaderLength = %i", hdr->HeaderLength);
 148         //Log_Log("IPv4", "DiffServices = %i", hdr->DiffServices);
 149         Log_Debug("IPv4", "TotalLength = %i", ntohs(hdr->TotalLength) );
 150         //Log_Log("IPv4", "Identifcation = %i", ntohs(hdr->Identifcation) );
 151         //Log_Log("IPv4", "TTL = %i", hdr->TTL );
 152         Log_Debug("IPv4", "Protocol = %i", hdr->Protocol );
 153         //Log_Log("IPv4", "HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
 154         Log_Debug("IPv4", "Source = %i.%i.%i.%i",
 155                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
 156         Log_Debug("IPv4", "Destination = %i.%i.%i.%i",
 157                 hdr->Destination.B[0], hdr->Destination.B[1],
 158                 hdr->Destination.B[2], hdr->Destination.B[3] );
 159         #endif
 160
 161         // Check that the version IS IPv4
 162         if(hdr->Version != 4) {
 163                 Log_Log("IPv4", "hdr->Version(%i) != 4", hdr->Version);
 164                 return;
 165         }
 166
 167         // Check Header checksum
 168         {
 169                 Uint16  hdrVal, compVal;
 170                 hdrVal = ntohs(hdr->HeaderChecksum);
 171                 hdr->HeaderChecksum = 0;
 172                 compVal = IPv4_Checksum(hdr, hdr->HeaderLength * 4);
 173                 if(hdrVal != compVal) {
 174                         Log_Log("IPv4", "Header checksum fails (%04x != %04x)", hdrVal, compVal);
 175                         return ;
 176                 }
 177                 hdr->HeaderChecksum = hdrVal;
 178         }
 179
 180         // Check Packet length
 181         if( ntohs(hdr->TotalLength) > Length) {
 182                 Log_Log("IPv4", "hdr->TotalLength(%i) > Length(%i)", ntohs(hdr->TotalLength), Length);
 183                 return;
 184         }
 185
 186         // TODO: Handle packet fragmentation
 187
 188         #if IPV4_TRACE
 189         Log_Debug("IPv4", "Proto 0x%x From %i.%i.%i.%i to %i.%i.%i.%i",
 190                 hdr->Protocol,
 191                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3],
 192                 hdr->Destination.B[0], hdr->Destination.B[1], hdr->Destination.B[2], hdr->Destination.B[3]
 193                 );
 194         #endif
 195
 196         // Get Data and Data Length
 197         dataLength = ntohs(hdr->TotalLength) - sizeof(tIPv4Header);
 198         data = &hdr->Options[0];
 199
 200         // Populate ARP cache from sniffing.
 201         // - Downside: Poisoning, polluting from routed packets
 202         //ARP_UpdateCache4(hdr->Source, From);
 203
 204         // Get Interface (allowing broadcasts)
 205         iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
 206
 207         // Firewall rules
 208         if( iface ) {
 209                 // Incoming Packets
 210                 ret = IPTables_TestChain("INPUT",
 211                         4, &hdr->Source, &hdr->Destination,
 212                         hdr->Protocol, 0,
 213                         dataLength, data
 214                         );
 215         }
 216         else {
 217                 // Routed packets
 218                 ret = IPTables_TestChain("FORWARD",
 219                         4, &hdr->Source, &hdr->Destination,
 220                         hdr->Protocol, 0,
 221                         dataLength, data
 222                         );
 223         }
 224         switch(ret)
 225         {
 226         // 0 - Allow
 227         case 0: break;
 228         // 1 - Silent Drop
 229         case 1:
 230                 Log_Debug("IPv4", "Silently dropping packet");
 231                 return ;
 232         case -1:
 233                 // Bad rule
 234                 break ;
 235         // Unknown, silent drop
 236         default:
 237                 Log_Warning("IPv4", "Unknown firewall rule");
 238                 return ;
 239         }
 240
 241         // Routing
 242         if(!iface)
 243         {
 244                 #if 0
 245                 tMacAddr        to;
 246                 tRoute  *rt;
 247
 248
 249                 // TODO: Put this in another thread to avoid delays in the RX thread
 250                 Log_Debug("IPv4", "Route the packet");
 251                 // Drop the packet if the TTL is zero
 252                 if( hdr->TTL == 0 ) {
 253                         Log_Warning("IPv4", "TODO: Send ICMP-Timeout when TTL exceeded");
 254                         return ;
 255                 }
 256
 257                 hdr->TTL --;
 258
 259                 rt = IPStack_FindRoute(4, NULL, &hdr->Destination);     // Get the route (gets the interface)
 260                 if( !rt || !rt->Interface )
 261                         return ;
 262                 to = ARP_Resolve4(rt->Interface, hdr->Destination);     // Resolve address
 263                 if( MAC_EQU(to, cMAC_ZERO) )
 264                         return ;
 265
 266                 // Send packet
 267                 Log_Log("IPv4", "Forwarding packet to %i.%i.%i.%i (via %i.%i.%i.%i)",
 268                         hdr->Destination.B[0], hdr->Destination.B[1],
 269                         hdr->Destination.B[2], hdr->Destination.B[3],
 270                         ((tIPv4*)rt->NextHop)->B[0], ((tIPv4*)rt->NextHop)->B[1],
 271                         ((tIPv4*)rt->NextHop)->B[2], ((tIPv4*)rt->NextHop)->B[3]);
 272                 Log_Warning("IPv4", "TODO: Implement forwarding with tIPStackBuffer");
 273 //              Link_SendPacket(rt->Interface->Adapter, IPV4_ETHERNET_ID, to, Length, Buffer);
 274                 #endif
 275
 276                 return ;
 277         }
 278
 279         // Populate ARP cache from recieved packets
 280         // - Should be safe
 281         ARP_UpdateCache4(hdr->Source, From);
 282
 283         // Send it on
 284         if( !gaIPv4_Callbacks[hdr->Protocol] ) {
 285                 Log_Log("IPv4", "Unknown Protocol %i", hdr->Protocol);
 286                 return ;
 287         }
 288
 289         gaIPv4_Callbacks[hdr->Protocol]( iface, &hdr->Source, dataLength, data );
 290 }
 291
 292 /**
 293  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 294  * \brief Searches an adapter for a matching address
 295  * \param Adapter       Incoming Adapter
 296  * \param Address       Destination Address
 297  * \param Broadcast     Allow broadcast packets
 298  */
 299 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 300 {
 301         tInterface      *iface = NULL, *zero_iface = NULL;
 302         Uint32  netmask;
 303         Uint32  addr, this;
 304
 305         ENTER("pAdapter xAddress bBroadcast", Adapter, Address, Broadcast);
 306
 307         addr = ntohl( Address.L );
 308         LOG("addr = 0x%x", addr);
 309
 310         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 311         {
 312                 if( iface->Adapter != Adapter ) continue;
 313                 if( iface->Type != 4 )  continue;
 314                 if( IP4_EQU(Address, *(tIPv4*)iface->Address) ) {
 315                         LOG("Exact match");
 316                         LEAVE('p', iface);
 317                         return iface;
 318                 }
 319
 320                 LOG("iface->Address = 0x%x", *(Uint32*)iface->Address);
 321
 322                 if( *(Uint32*)iface->Address == 0 ) {
 323                         if( zero_iface ) {
 324                                 Log_Notice("IPv4", "Multiple 0.0.0.0 interfaces on the same adapter, ignoring");
 325                         }
 326                         else {
 327                                 zero_iface = iface;
 328                                 LOG("Zero IF %p", iface);
 329                         }
 330                         continue ;
 331                 }
 332
 333                 if( !Broadcast )        continue;
 334
 335                 // Check for broadcast
 336                 this = ntohl( ((tIPv4*)iface->Address)->L );
 337                 netmask = IPv4_Netmask(iface->SubnetBits);
 338                 LOG("iface addr = 0x%x, netmask = 0x%x (bits = %i)", this, netmask, iface->SubnetBits);
 339
 340                 if( (addr & netmask) == (this & netmask) && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 341                 {
 342                         LOG("Broadcast match");
 343                         LEAVE('p', iface);
 344                         return iface;
 345                 }
 346         }
 347
 348         // Special case for intefaces that are being DHCP configured
 349         // - If the interface address is 0.0.0.0, then if there is no match for the
 350         //   destination the packet is treated as if it was addressed to 0.0.0.0
 351         if( zero_iface && Broadcast )
 352         {
 353                 LOG("Using 0.0.0.0 interface with magic!");
 354                 LEAVE('p', zero_iface);
 355                 return zero_iface;
 356         }
 357
 358         LEAVE('n');
 359         return NULL;
 360 }
 361
 362 /**
 363  * \brief Convert a network prefix to a netmask
 364  * \param FixedBits     Netmask size (/n)
 365  *
 366  * For example /24 will become 255.255.255.0 (0xFFFFFF00)
 367  */
 368 Uint32 IPv4_Netmask(int FixedBits)
 369 {
 370         Uint32  ret = 0xFFFFFFFF;
 371         if( FixedBits == 0 )
 372                 return 0;
 373         if( FixedBits < 32 )
 374         {
 375                 ret >>= (32-FixedBits);
 376                 ret <<= (32-FixedBits);
 377         }
 378         // Returns a native endian netmask
 379         return ret;
 380 }
 381
 382 /**
 383  * \brief Calculate the IPv4 Checksum
 384  * \param Buf   Input buffer
 385  * \param Size  Size of input
 386  *
 387  * One's complement sum of all 16-bit words (bitwise inverted)
 388  */
 389 Uint16 IPv4_Checksum(const void *Buf, size_t Length)
 390 {
 391         const Uint16    *words = Buf;
 392         Uint32  sum = 0;
 393          int    i;
 394
 395         // Sum all whole words
 396         for(i = 0; i < Length/2; i++ )
 397         {
 398                 sum += ntohs(words[i]);
 399         }
 400         if( Length & 1 )
 401                 sum += ntohs( words[i] & 0xFF );
 402
 403         // Apply one's complement
 404         while (sum >> 16)
 405                 sum = (sum & 0xFFFF) + (sum >> 16);
 406
 407         return ~sum;
 408 }
 409
 410 /**
 411  * \brief Sends an ICMP Echo and waits for a reply
 412  * \param IFace Interface
 413  * \param Addr  Destination address
 414  */
 415 int IPv4_Ping(tInterface *IFace, tIPv4 Addr)
 416 {
 417         return ICMP_Ping(IFace, Addr);
 418 }