3 * - IPv4 Protcol Handling
9 #include "hwaddr_cache.h"
13 #define DEFAULT_TTL 32
14 #define IPV4_TRACE 1 // set to 1 to enable packet tracing
17 extern tInterface *gIP_Interfaces;
18 extern void ICMP_Initialise();
19 extern int ICMP_Ping(tInterface *Interface, tIPv4 Addr);
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);
33 tIPErrorCallback* err_cb;
34 } gaIPv4_Callbacks[256];
38 * \brief Initialise the IPv4 Code
43 Link_RegisterType(IPV4_ETHERNET_ID, IPv4_int_GetPacket);
48 * \brief Registers a callback
49 * \param ID 8-bit packet type ID
50 * \param Callback Callback function
52 int IPv4_RegisterCallback(int ID, tIPRxCallback *RxCallback, tIPErrorCallback *ErrCallback)
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;
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
71 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, tIPStackBuffer *Buffer)
75 int length = IPStack_Buffer_GetLength(Buffer);
77 // --- Resolve destination MAC address
78 tMacAddr to = HWCache_Resolve(Iface, &Address);
79 if( MAC_EQU(to, cMAC_ZERO) ) {
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]);
86 // --- Handle OUTPUT firewall rules
87 // TODO: Update firewall rules for tIPStackBuffer
89 int ret = IPTables_TestChain("OUTPUT",
90 4, (tIPv4*)Iface->Address, &Address,
94 // Just drop it (with an error)
95 Log_Notice("IPv4", "Firewall dropped packet");
100 // --- Initialise header
102 hdr.HeaderLength = sizeof(tIPv4Header)/4;
103 hdr.DiffServices = 0; // TODO: Check
106 hdr.DontFragment = 0;
107 hdr.MoreFragments = 0;
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;
119 // Actually set checksum (zeroed above)
120 hdr.HeaderChecksum = htons( IPv4_Checksum(&hdr, sizeof(tIPv4Header)) );
122 IPStack_Buffer_AppendSubBuffer(Buffer, sizeof(tIPv4Header), 0, &hdr, NULL, NULL);
125 Log_Log("IPv4", "Sending packet to %i.%i.%i.%i",
126 Address.B[0], Address.B[1], Address.B[2], Address.B[3]);
128 Link_SendPacket(Iface->Adapter, IPV4_ETHERNET_ID, to, Buffer);
133 * \fn void IPv4_int_GetPacket(tInterface *Adapter, tMacAddr From, int Length, void *Buffer)
134 * \brief Process an IPv4 Packet
136 void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
138 tIPv4Header *hdr = Buffer;
143 if(Length < sizeof(tIPv4Header)) return;
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] );
161 // Check that the version IS IPv4
162 if(hdr->Version != 4) {
163 Log_Log("IPv4", "hdr->Version(%i) != 4", hdr->Version);
167 // Check Header checksum
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);
177 hdr->HeaderChecksum = hdrVal;
180 // Check Packet length
181 if( ntohs(hdr->TotalLength) > Length) {
182 Log_Log("IPv4", "hdr->TotalLength(%i) > Length(%i)", ntohs(hdr->TotalLength), Length);
186 // TODO: Handle packet fragmentation
189 Log_Debug("IPv4", "Proto 0x%x From %i.%i.%i.%i to %i.%i.%i.%i",
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]
196 // Get Data and Data Length
197 dataLength = ntohs(hdr->TotalLength) - sizeof(tIPv4Header);
198 data = &hdr->Options[0];
200 // Get Interface (allowing broadcasts)
201 tInterface *iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
206 ret = IPTables_TestChain("INPUT",
207 4, &hdr->Source, &hdr->Destination,
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");
221 ret = IPTables_TestChain("FORWARD",
222 4, &hdr->Source, &hdr->Destination,
233 Log_Debug("IPv4", "Silently dropping packet");
238 // Unknown, silent drop
240 Log_Warning("IPv4", "Unknown firewall rule");
247 //IPStack_RoutePacket(4, &hdr->Destination, Length, Buffer);
251 // Populate ARP cache from recieved packets
253 if( IPStack_CompareAddress(4, &hdr->Source, iface->Address, iface->SubnetBits) )
255 HWCache_Set(Adapter, 4, &hdr->Source, &From);
259 if( !gaIPv4_Callbacks[hdr->Protocol].rx_cb ) {
260 Log_Log("IPv4", "Unknown Protocol %i", hdr->Protocol);
264 gaIPv4_Callbacks[hdr->Protocol].rx_cb( iface, &hdr->Source, dataLength, data );
268 * Handles an error from the ICMPv4 code, 'Buf' contains part of an IPv4 packet
270 void IPv4_HandleError(tInterface *Iface, tIPErrorMode Mode, size_t Length, const void *Buf)
272 if(Length < sizeof(tIPv4Header)) return;
273 const tIPv4Header* hdr = Buf;
274 if(hdr->Version != 4) return;
276 // Get Data and Data Length
277 size_t dataLength = MIN(Length, ntohs(hdr->TotalLength)) - sizeof(tIPv4Header);
278 const void *data = &hdr->Options[0];
280 if( gaIPv4_Callbacks[hdr->Protocol].err_cb )
281 gaIPv4_Callbacks[hdr->Protocol].err_cb(Iface, Mode, &hdr->Source, dataLength, data);
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
291 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
293 tInterface *zero_iface = NULL;
295 ENTER("pAdapter xAddress bBroadcast", Adapter, Address, Broadcast);
297 Uint32 addr = ntohl( Address.L );
298 LOG("addr = 0x%x", addr);
300 for( tInterface *iface = gIP_Interfaces; iface; iface = iface->Next)
302 if( iface->Adapter != Adapter ) continue;
303 if( iface->Type != 4 ) continue;
304 if( IP4_EQU(Address, *(tIPv4*)iface->Address) ) {
310 LOG("iface->Address = 0x%x", *(Uint32*)iface->Address);
312 if( *(Uint32*)iface->Address == 0 ) {
314 Log_Notice("IPv4", "Multiple 0.0.0.0 interfaces on the same adapter, ignoring");
318 LOG("Zero IF %p", iface);
323 if( !Broadcast ) continue;
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);
330 if( (addr & netmask) == (this & netmask) && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
332 LOG("Broadcast match");
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 )
343 LOG("Using 0.0.0.0 interface with magic!");
344 LEAVE('p', zero_iface);
353 * \brief Convert a network prefix to a netmask
354 * \param FixedBits Netmask size (/n)
356 * For example /24 will become 255.255.255.0 (0xFFFFFF00)
358 Uint32 IPv4_Netmask(int FixedBits)
360 Uint32 ret = 0xFFFFFFFF;
365 ret >>= (32-FixedBits);
366 ret <<= (32-FixedBits);
368 // Returns a native endian netmask
373 * \brief Calculate the IPv4 Checksum
374 * \param Buf Input buffer
375 * \param Size Size of input
377 * One's complement sum of all 16-bit words (bitwise inverted)
379 Uint16 IPv4_Checksum(const void *Buf, size_t Length)
381 //Debug_HexDump("IPv4_Checksum", Buf, Length);
382 const Uint16 *words = Buf;
386 // Sum all whole words
387 for(i = 0; i < Length/2; i++ )
389 sum += ntohs(words[i]);
392 sum += ntohs( words[i] & 0xFF );
394 // Apply one's complement
396 sum = (sum & 0xFFFF) + (sum >> 16);
402 * \brief Sends an ICMP Echo and waits for a reply
403 * \param IFace Interface
404 * \param Addr Destination address
406 int IPv4_Ping(tInterface *IFace, tIPv4 Addr)
408 return ICMP_Ping(IFace, Addr);