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 "hwaddr_cache.h"
  10 #include "firewall.h"
  11
  12 // === CONSTANTS ===
  13 #define DEFAULT_TTL     32
  14 #define IPV4_TRACE      1       // set to 1 to enable packet tracing
  15
  16 // === IMPORTS ===
  17 extern tInterface       *gIP_Interfaces;
  18 extern void     ICMP_Initialise();
  19 extern  int     ICMP_Ping(tInterface *Interface, tIPv4 Addr);
  20
  21 // === PROTOTYPES ===
  22  int    IPv4_Initialise();
  23 // int  IPv4_RegisterCallback(int ID, tIPRxCallback Callback, );
  24 void    IPv4_int_GetPacket(tAdapter *Interface, tMacAddr From, int Length, void *Buffer);
  25 tInterface      *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
  26 Uint32  IPv4_Netmask(int FixedBits);
  27 Uint16  IPv4_Checksum(const void *Buf, size_t Length);
  28  int    IPv4_Ping(tInterface *Iface, tIPv4 Addr);
  29
  30 // === GLOBALS ===
  31 struct {
  32         tIPRxCallback*  rx_cb;
  33         tIPErrorCallback*       err_cb;
  34 } gaIPv4_Callbacks[256];
  35
  36 // === CODE ===
  37 /**
  38  * \brief Initialise the IPv4 Code
  39  */
  40 int IPv4_Initialise()
  41 {
  42         ICMP_Initialise();
  43         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  44         return 1;
  45 }
  46
  47 /**
  48  * \brief Registers a callback
  49  * \param ID    8-bit packet type ID
  50  * \param Callback      Callback function
  51  */
  52 int IPv4_RegisterCallback(int ID, tIPRxCallback *RxCallback, tIPErrorCallback *ErrCallback)
  53 {
  54         if( ID < 0 || ID > 255 )        return 0;
  55         if( gaIPv4_Callbacks[ID].rx_cb )        return 0;
  56         gaIPv4_Callbacks[ID].rx_cb = RxCallback;
  57         gaIPv4_Callbacks[ID].err_cb = ErrCallback;
  58         return 1;
  59 }
  60
  61 /**
  62  * \brief Creates and sends an IPv4 Packet
  63  * \param Iface Interface
  64  * \param Address       Destination IP
  65  * \param Protocol      Protocol ID
  66  * \param ID    Some random ID number
  67  * \param Length        Data Length
  68  * \param Data  Packet Data
  69  * \return Boolean Success
  70  */
  71 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, tIPStackBuffer *Buffer)
  72 {
  73         tIPv4Header     hdr;
  74
  75         int length = IPStack_Buffer_GetLength(Buffer);
  76
  77         // --- Resolve destination MAC address
  78         tMacAddr to = HWCache_Resolve(Iface, &Address);
  79         if( MAC_EQU(to, cMAC_ZERO) ) {
  80                 // No route to host
  81                 Log_Notice("IPv4", "No route to host %i.%i.%i.%i",
  82                         Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
  83                 return 0;
  84         }
  85
  86         // --- Handle OUTPUT firewall rules
  87         // TODO: Update firewall rules for tIPStackBuffer
  88         #if 0
  89         int ret = IPTables_TestChain("OUTPUT",
  90                 4, (tIPv4*)Iface->Address, &Address,
  91                 Protocol, 0,
  92                 length, Data);
  93         if(ret > 0) {
  94                 // Just drop it (with an error)
  95                 Log_Notice("IPv4", "Firewall dropped packet");
  96                 return 0;
  97         }
  98         #endif
  99
 100         // --- Initialise header
 101         hdr.Version = 4;
 102         hdr.HeaderLength = sizeof(tIPv4Header)/4;
 103         hdr.DiffServices = 0;   // TODO: Check
 104
 105         hdr.Reserved = 0;
 106         hdr.DontFragment = 0;
 107         hdr.MoreFragments = 0;
 108         hdr.FragOffLow = 0;
 109         hdr.FragOffHi = 0;
 110
 111         hdr.TotalLength = htons( sizeof(tIPv4Header) + length );
 112         hdr.Identifcation = htons( ID );        // TODO: Check
 113         hdr.TTL = DEFAULT_TTL;
 114         hdr.Protocol = Protocol;
 115         hdr.HeaderChecksum = 0; // Will be set later
 116         hdr.Source = *(tIPv4*)Iface->Address;
 117         hdr.Destination = Address;
 118
 119         // Actually set checksum (zeroed above)
 120         hdr.HeaderChecksum = htons( IPv4_Checksum(&hdr, sizeof(tIPv4Header)) );
 121
 122         IPStack_Buffer_AppendSubBuffer(Buffer, sizeof(tIPv4Header), 0, &hdr, NULL, NULL);
 123
 124         #if IPV4_TRACE
 125         Log_Log("IPv4", "Sending packet to %i.%i.%i.%i",
 126                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
 127         #endif
 128         Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, Buffer);
 129         return 1;
 130 }
 131
 132 /**
 133  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
 134  * \brief Process an IPv4 Packet
 135  */
 136 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
 137 {
 138         tIPv4Header     *hdr = Buffer;
 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         // Get Interface (allowing broadcasts)
 201         tInterface *iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
 202
 203         // Firewall rules
 204         if( iface ) {
 205                 // Incoming Packets
 206                 ret = IPTables_TestChain("INPUT",
 207                         4, &hdr->Source, &hdr->Destination,
 208                         hdr->Protocol, 0,
 209                         dataLength, data
 210                         );
 211         }
 212         else {
 213                 // Routed packets
 214                 // Drop the packet if the TTL is zero
 215                 if( hdr->TTL == 0 ) {
 216                         Log_Warning("IPv4", "TODO: Send ICMP-Timeout when TTL exceeded");
 217                         return ;
 218                 }
 219                 hdr->TTL --;
 220
 221                 ret = IPTables_TestChain("FORWARD",
 222                         4, &hdr->Source, &hdr->Destination,
 223                         hdr->Protocol, 0,
 224                         dataLength, data
 225                         );
 226         }
 227         switch(ret)
 228         {
 229         // 0 - Allow
 230         case 0: break;
 231         // 1 - Silent Drop
 232         case 1:
 233                 Log_Debug("IPv4", "Silently dropping packet");
 234                 return ;
 235         case -1:
 236                 // Bad rule
 237                 break ;
 238         // Unknown, silent drop
 239         default:
 240                 Log_Warning("IPv4", "Unknown firewall rule");
 241                 return ;
 242         }
 243
 244         // Routing
 245         if(!iface)
 246         {
 247                 //IPStack_RoutePacket(4, &hdr->Destination, Length, Buffer);
 248                 return ;
 249         }
 250
 251         // Populate ARP cache from recieved packets
 252         // - Should be safe
 253         if( IPStack_CompareAddress(4, &hdr->Source, iface->Address, iface->SubnetBits) )
 254         {
 255                 HWCache_Set(Adapter, 4, &hdr->Source, &From);
 256         }
 257
 258         // Send it on
 259         if( !gaIPv4_Callbacks[hdr->Protocol].rx_cb ) {
 260                 Log_Log("IPv4", "Unknown Protocol %i", hdr->Protocol);
 261                 return ;
 262         }
 263
 264         gaIPv4_Callbacks[hdr->Protocol].rx_cb( iface, &hdr->Source, dataLength, data );
 265 }
 266
 267 /*
 268  * Handles an error from the ICMPv4 code, 'Buf' contains part of an IPv4 packet
 269  */
 270 void IPv4_HandleError(tInterface *Iface, tIPErrorMode Mode, size_t Length, const void *Buf)
 271 {
 272         if(Length < sizeof(tIPv4Header))        return;
 273         const tIPv4Header*      hdr = Buf;
 274         if(hdr->Version != 4)   return;
 275
 276         // Get Data and Data Length
 277         size_t dataLength = MIN(Length, ntohs(hdr->TotalLength)) - sizeof(tIPv4Header);
 278         const void *data = &hdr->Options[0];
 279
 280         if( gaIPv4_Callbacks[hdr->Protocol].err_cb )
 281                 gaIPv4_Callbacks[hdr->Protocol].err_cb(Iface, Mode, &hdr->Source, dataLength, data);
 282 }
 283
 284 /**
 285  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 286  * \brief Searches an adapter for a matching address
 287  * \param Adapter       Incoming Adapter
 288  * \param Address       Destination Address
 289  * \param Broadcast     Allow broadcast packets
 290  */
 291 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 292 {
 293         tInterface      *zero_iface = NULL;
 294
 295         ENTER("pAdapter xAddress bBroadcast", Adapter, Address, Broadcast);
 296
 297         Uint32 addr = ntohl( Address.L );
 298         LOG("addr = 0x%x", addr);
 299
 300         for( tInterface *iface = gIP_Interfaces; iface; iface = iface->Next)
 301         {
 302                 if( iface->Adapter != Adapter ) continue;
 303                 if( iface->Type != 4 )  continue;
 304                 if( IP4_EQU(Address, *(tIPv4*)iface->Address) ) {
 305                         LOG("Exact match");
 306                         LEAVE('p', iface);
 307                         return iface;
 308                 }
 309
 310                 LOG("iface->Address = 0x%x", *(Uint32*)iface->Address);
 311
 312                 if( *(Uint32*)iface->Address == 0 ) {
 313                         if( zero_iface ) {
 314                                 Log_Notice("IPv4", "Multiple 0.0.0.0 interfaces on the same adapter, ignoring");
 315                         }
 316                         else {
 317                                 zero_iface = iface;
 318                                 LOG("Zero IF %p", iface);
 319                         }
 320                         continue ;
 321                 }
 322
 323                 if( !Broadcast )        continue;
 324
 325                 // Check for broadcast
 326                 Uint32 this = ntohl( ((tIPv4*)iface->Address)->L );
 327                 Uint32 netmask = IPv4_Netmask(iface->SubnetBits);
 328                 LOG("iface addr = 0x%x, netmask = 0x%x (bits = %i)", this, netmask, iface->SubnetBits);
 329
 330                 if( (addr & netmask) == (this & netmask) && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 331                 {
 332                         LOG("Broadcast match");
 333                         LEAVE('p', iface);
 334                         return iface;
 335                 }
 336         }
 337
 338         // Special case for intefaces that are being DHCP configured
 339         // - If the interface address is 0.0.0.0, then if there is no match for the
 340         //   destination the packet is treated as if it was addressed to 0.0.0.0
 341         if( zero_iface && Broadcast )
 342         {
 343                 LOG("Using 0.0.0.0 interface with magic!");
 344                 LEAVE('p', zero_iface);
 345                 return zero_iface;
 346         }
 347
 348         LEAVE('n');
 349         return NULL;
 350 }
 351
 352 /**
 353  * \brief Convert a network prefix to a netmask
 354  * \param FixedBits     Netmask size (/n)
 355  *
 356  * For example /24 will become 255.255.255.0 (0xFFFFFF00)
 357  */
 358 Uint32 IPv4_Netmask(int FixedBits)
 359 {
 360         Uint32  ret = 0xFFFFFFFF;
 361         if( FixedBits == 0 )
 362                 return 0;
 363         if( FixedBits < 32 )
 364         {
 365                 ret >>= (32-FixedBits);
 366                 ret <<= (32-FixedBits);
 367         }
 368         // Returns a native endian netmask
 369         return ret;
 370 }
 371
 372 /**
 373  * \brief Calculate the IPv4 Checksum
 374  * \param Buf   Input buffer
 375  * \param Size  Size of input
 376  *
 377  * One's complement sum of all 16-bit words (bitwise inverted)
 378  */
 379 Uint16 IPv4_Checksum(const void *Buf, size_t Length)
 380 {
 381         //Debug_HexDump("IPv4_Checksum", Buf, Length);
 382         const Uint16    *words = Buf;
 383         Uint32  sum = 0;
 384          int    i;
 385
 386         // Sum all whole words
 387         for(i = 0; i < Length/2; i++ )
 388         {
 389                 sum += ntohs(words[i]);
 390         }
 391         if( Length & 1 )
 392                 sum += ntohs( words[i] & 0xFF );
 393
 394         // Apply one's complement
 395         while (sum >> 16)
 396                 sum = (sum & 0xFFFF) + (sum >> 16);
 397
 398         return ~sum;
 399 }
 400
 401 /**
 402  * \brief Sends an ICMP Echo and waits for a reply
 403  * \param IFace Interface
 404  * \param Addr  Destination address
 405  */
 406 int IPv4_Ping(tInterface *IFace, tIPv4 Addr)
 407 {
 408         return ICMP_Ping(IFace, Addr);
 409 }