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