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
   9 #define DEFAULT_TTL     32
  10
  11 // === IMPORTS ===
  12 extern tInterface       *gIP_Interfaces;
  13 extern void     ICMP_Initialise();
  14 extern  int     ICMP_Ping(tInterface *Interface, tIPv4 Addr);
  15 extern void     UDP_Initialise();
  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(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         UDP_Initialise();
  38         Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
  39         return 1;
  40 }
  41
  42 /**
  43  * \fn int IPv4_RegisterCallback( int ID, tIPCallback Callback )
  44  * \brief Registers a callback
  45  */
  46 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  47 {
  48         if( ID < 0 || ID > 255 )        return 0;
  49         if( gaIPv4_Callbacks[ID] )      return 0;
  50         gaIPv4_Callbacks[ID] = Callback;
  51         return 1;
  52 }
  53
  54 /**
  55  * \brief Creates and sends an IPv4 Packet
  56  */
  57 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, void *Data)
  58 {
  59         tMacAddr        to = ARP_Resolve4(Iface, Address);
  60          int    bufSize = sizeof(tIPv4Header) + Length;
  61         char    buf[bufSize];
  62         tIPv4Header     *hdr = (void*)buf;
  63
  64         memcpy(&hdr->Options[0], Data, Length);
  65         hdr->Version = 4;
  66         hdr->HeaderLength = htons( sizeof(tIPv4Header) );
  67         hdr->DiffServices = 0;  // TODO: Check
  68         hdr->TotalLength = htons( bufSize );
  69         hdr->Identifcation = htons( ID );       // TODO: Check
  70         hdr->TTL = DEFAULT_TTL;
  71         hdr->Protocol = Protocol;
  72         hdr->HeaderChecksum = 0;        // Will be set later
  73         hdr->Source = Iface->IP4.Address;
  74         hdr->Destination = Address;
  75         hdr->HeaderChecksum = htons( IPv4_Checksum(hdr, sizeof(tIPv4Header)) );
  76
  77         Log("[IPv4 ] Sending packet to %i.%i.%i.%i",
  78                 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
  79         Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, bufSize, buf);
  80         return 1;
  81 }
  82
  83 /**
  84  * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
  85  * \brief Process an IPv4 Packet
  86  */
  87 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
  88 {
  89         tIPv4Header     *hdr = Buffer;
  90         tInterface      *iface;
  91         Uint8   *data;
  92          int    dataLength;
  93         if(Length < sizeof(tIPv4Header))        return;
  94
  95         //Log("[IPv4 ] Version = %i", hdr->Version);
  96         Log("[IPv4 ] HeaderLength = %i", hdr->HeaderLength);
  97         Log("[IPv4 ] DiffServices = %i", hdr->DiffServices);
  98         //Log("[IPv4 ] TotalLength = %i", ntohs(hdr->TotalLength) );
  99         //Log("[IPv4 ] Identifcation = %i", ntohs(hdr->Identifcation) );
 100         //Log("[IPv4 ] TTL = %i", hdr->TTL );
 101         Log("[IPv4 ] Protocol = %i", hdr->Protocol );
 102         //Log("[IPv4 ] HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
 103         Log("[IPv4 ] Source = %i.%i.%i.%i",
 104                 hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
 105         Log("[IPv4 ] Destination = %i.%i.%i.%i",
 106                 hdr->Destination.B[0], hdr->Destination.B[1],
 107                 hdr->Destination.B[2], hdr->Destination.B[3] );
 108
 109         // Check that the version IS IPv4
 110         if(hdr->Version != 4) {
 111                 Log("[IPv4 ] hdr->Version(%i) != 4", hdr->Version);
 112                 return;
 113         }
 114
 115         // Check Header checksum
 116         //TODO
 117
 118         // Check Packet length
 119         if( ntohs(hdr->TotalLength) > Length) {
 120                 Log("[IPv4 ] hdr->TotalLength(%i) > Length(%i)", hdr->TotalLength, Length);
 121                 return;
 122         }
 123
 124         // Get Interface (allowing broadcasts)
 125         iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
 126         if(!iface) {
 127                 Log("[IPv4 ] Ignoring Packet (Not for us)");
 128                 return; // Not for us? Well, let's ignore it
 129         }
 130
 131         // Defragment
 132         //TODO
 133
 134         dataLength = hdr->TotalLength - sizeof(tIPv4Header);
 135         data = &hdr->Options[0];
 136
 137         // Send it on
 138         gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
 139 }
 140
 141 /**
 142  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
 143  * \brief Searches an adapter for a matching address
 144  */
 145 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 146 {
 147         tInterface      *iface = NULL;
 148         Uint32  netmask;
 149         Uint32  addr, this;
 150
 151         addr = ntohl( Address.L );
 152
 153         for( iface = gIP_Interfaces; iface; iface = iface->Next)
 154         {
 155                 if( iface->Adapter != Adapter ) continue;
 156                 if( iface->Type != 4 )  continue;
 157                 if( IP4_EQU(Address, iface->IP4.Address) )
 158                         return iface;
 159
 160                 if( !Broadcast )        continue;
 161
 162                 this = ntohl( iface->IP4.Address.L );
 163
 164                 // Check for broadcast
 165                 netmask = IPv4_Netmask(iface->IP4.SubnetBits);
 166
 167                 //Log("netmask = 0x%08x", netmask);
 168                 //Log("addr = 0x%08x", addr);
 169                 //Log("this = 0x%08x", this);
 170                 //Log("%08x == %08x && %08x == %08x",
 171                 //      (addr & netmask), (this & netmask),
 172                 //      (addr & ~netmask), (0xFFFFFFFF & ~netmask)
 173                 //      );
 174                 if( (addr & netmask) == (this & netmask)
 175                  && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
 176                         return iface;
 177         }
 178         return NULL;
 179 }
 180
 181 /**
 182  * \brief Convert a network prefix to a netmask
 183  *
 184  * For example /24 will become 255.255.255.0
 185  */
 186 Uint32 IPv4_Netmask(int FixedBits)
 187 {
 188         Uint32  ret = 0xFFFFFFFF;
 189         ret >>= (32-FixedBits);
 190         ret <<= (32-FixedBits);
 191         // Returs a little endian netmask
 192         return ret;
 193 }
 194
 195 /**
 196  * \brief Calculate the IPv4 Checksum
 197  */
 198 Uint16 IPv4_Checksum(void *Buf, int Size)
 199 {
 200         Uint16  sum = 0;
 201         Uint16  *arr = Buf;
 202          int    i;
 203
 204         Size = (Size + 1) >> 1;
 205         for(i = 0; i < Size; i++ )
 206         {
 207                 if((int)sum + arr[i] > 0xFFFF)
 208                         sum ++; // Simulate 1's complement
 209                 sum += arr[i];
 210         }
 211         return ~sum;
 212 }
 213
 214 /**
 215  * \brief Sends an ICMP Echo and waits for a reply
 216  */
 217 int IPv4_Ping(tInterface *Iface, tIPv4 Addr)
 218 {
 219         return ICMP_Ping(Iface, Addr);
 220 }