3 * - Address Resolution Protocol
4 * - Part of the IPv4 protocol
12 #define ARP_CACHE_SIZE 64
13 #define ARP_MAX_AGE (60*60*1000) // 1Hr
16 extern tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast);
18 extern tInterface *IPv6_GetInterface(tAdapter *Adapter, tIPv6 Address, int Broadcast);
23 tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address);
24 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer);
33 int giARP_Cache4Space;
42 int giARP_Cache6Space;
45 volatile int giARP_LastUpdateID = 0;
49 * \fn int ARP_Initialise()
50 * \brief Initalise the ARP section
54 gaARP_Cache4 = malloc( ARP_CACHE_SIZE * sizeof(struct sARP_Cache4) );
55 memset( gaARP_Cache4, 0, ARP_CACHE_SIZE * sizeof(struct sARP_Cache4) );
56 giARP_Cache4Space = ARP_CACHE_SIZE;
59 gaARP_Cache6 = malloc( ARP_CACHE_SIZE * sizeof(struct sARP_Cache6) );
60 memset( gaARP_Cache6, 0, ARP_CACHE_SIZE * sizeof(struct sARP_Cache6) );
61 giARP_Cache6Space = ARP_CACHE_SIZE;
64 Link_RegisterType(0x0806, ARP_int_GetPacket);
69 * \brief Resolves a MAC address from an IPv4 address
71 tMacAddr ARP_Resolve4(tInterface *Interface, tIPv4 Address)
75 struct sArpRequest4 req;
78 ENTER("pInterface xAddress", Interface, Address);
80 // Check for broadcast
85 return cMAC_BROADCAST;
88 // Check routing tables if not on this subnet
89 if( IPStack_CompareAddress(4, &Address, Interface->Address, Interface->SubnetBits) == 0 )
91 tRoute *route = IPStack_FindRoute(4, Interface, &Address);
92 // If the next hop is defined, use it
93 // - 0.0.0.0 as the next hop means "no next hop / direct"
94 if( route && ((tIPv4*)route->NextHop)->L != 0 )
96 // Recursion: see /Recursion/
97 LOG("Recursing with %s", IPStack_PrintAddress(4, route->NextHop));
99 return ARP_Resolve4(Interface, *(tIPv4*)route->NextHop);
101 // No route, fall though
106 // Check for broadcast
107 netmask = IPv4_Netmask(Interface->SubnetBits);
108 if( (Address.L & ~netmask) == (0xFFFFFFFF & ~netmask) )
110 LOG("Local Broadcast");
112 return cMAC_BROADCAST;
117 Mutex_Acquire( &glARP_Cache4 );
118 for( i = 0; i < giARP_Cache4Space; i++ )
120 if(gaARP_Cache4[i].IP.L != Address.L) continue;
122 // Check if the entry needs to be refreshed
123 if( now() - gaARP_Cache4[i].LastUpdate > ARP_MAX_AGE ) break;
125 Mutex_Release( &glARP_Cache4 );
126 LOG("Return %x:%x:%x:%x:%x:%x",
127 gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
128 gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
129 gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]
132 return gaARP_Cache4[i].MAC;
134 Mutex_Release( &glARP_Cache4 );
136 lastID = giARP_LastUpdateID;
139 Log_Log("ARP4", "Asking for address %i.%i.%i.%i",
140 Address.B[0], Address.B[1], Address.B[2], Address.B[3]
142 req.HWType = htons(0x0001); // Ethernet
143 req.Type = htons(0x0800);
146 req.Request = htons(1);
147 req.SourceMac = Interface->Adapter->MacAddr;
148 req.SourceIP = *(tIPv4*)Interface->Address;
149 req.DestMac = cMAC_BROADCAST;
150 req.DestIP = Address;
153 Link_SendPacket(Interface->Adapter, 0x0806, req.DestMac, sizeof(struct sArpRequest4), &req);
155 timeout = now() + Interface->TimeoutDelay;
160 while(lastID == giARP_LastUpdateID && now() < timeout) {
164 if( now() >= timeout ) {
165 Log_Log("ARP4", "Timeout");
169 lastID = giARP_LastUpdateID;
171 Mutex_Acquire( &glARP_Cache4 );
172 for( i = 0; i < giARP_Cache4Space; i++ )
174 if(gaARP_Cache4[i].IP.L != Address.L) continue;
176 Mutex_Release( &glARP_Cache4 );
177 Log_Debug("ARP4", "Return %02x:%02x:%02x:%02x:%02x:%02x",
178 gaARP_Cache4[i].MAC.B[0], gaARP_Cache4[i].MAC.B[1],
179 gaARP_Cache4[i].MAC.B[2], gaARP_Cache4[i].MAC.B[3],
180 gaARP_Cache4[i].MAC.B[4], gaARP_Cache4[i].MAC.B[5]);
181 return gaARP_Cache4[i].MAC;
183 Mutex_Release( &glARP_Cache4 );
186 tMacAddr ret = {{0,0,0,0,0,0}};
192 * \brief Updates the ARP Cache entry for an IPv4 Address
194 void ARP_UpdateCache4(tIPv4 SWAddr, tMacAddr HWAddr)
200 // Find an entry for the IP address in the cache
201 Mutex_Acquire(&glARP_Cache4);
202 for( i = giARP_Cache4Space; i--; )
204 if(gaARP_Cache4[oldest].LastUpdate > gaARP_Cache4[i].LastUpdate) {
207 if( gaARP_Cache4[i].IP.L == SWAddr.L ) break;
208 if( gaARP_Cache4[i].LastUpdate == 0 && free == -1 ) free = i;
210 // If there was no match, we need to make one
218 Log_Log("ARP4", "Caching %i.%i.%i.%i (%02x:%02x:%02x:%02x:%02x:%02x) in %i",
219 SWAddr.B[0], SWAddr.B[1], SWAddr.B[2], SWAddr.B[3],
220 HWAddr.B[0], HWAddr.B[1], HWAddr.B[2], HWAddr.B[3], HWAddr.B[4], HWAddr.B[5],
224 gaARP_Cache4[i].IP = SWAddr;
225 gaARP_Cache4[i].MAC = HWAddr;
226 gaARP_Cache4[i].LastUpdate = now();
227 giARP_LastUpdateID ++;
228 Mutex_Release(&glARP_Cache4);
233 * \brief Updates the ARP Cache entry for an IPv6 Address
235 void ARP_UpdateCache6(tIPv6 SWAddr, tMacAddr HWAddr)
241 // Find an entry for the MAC address in the cache
242 Mutex_Acquire(&glARP_Cache6);
243 for( i = giARP_Cache6Space; i--; )
245 if(gaARP_Cache6[oldest].LastUpdate > gaARP_Cache6[i].LastUpdate) {
248 if( MAC_EQU(gaARP_Cache6[i].MAC, HWAddr) ) break;
249 if( gaARP_Cache6[i].LastUpdate == 0 && free == -1 ) free = i;
251 // If there was no match, we need to make one
257 gaARP_Cache6[i].MAC = HWAddr;
260 gaARP_Cache6[i].IP = SWAddr;
261 gaARP_Cache6[i].LastUpdate = now();
262 giARP_LastUpdateID ++;
263 Mutex_Release(&glARP_Cache6);
268 * \fn void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
269 * \brief Called when an ARP packet is recieved
271 void ARP_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buffer)
273 tArpRequest4 *req4 = Buffer;
275 tArpRequest6 *req6 = Buffer;
279 // Sanity Check Packet
280 if( Length < (int)sizeof(tArpRequest4) ) {
281 Log_Log("ARP", "Recieved undersized packet");
284 if( ntohs(req4->Type) != 0x0800 ) {
285 Log_Log("ARP", "Recieved a packet with a bad type (0x%x)", ntohs(req4->Type));
288 if( req4->HWSize != 6 ) {
289 Log_Log("ARP", "Recieved a packet with HWSize != 6 (%i)", req4->HWSize);
292 #if ARP_DETECT_SPOOFS
293 if( !MAC_EQU(req4->SourceMac, From) ) {
294 Log_Log("ARP", "ARP spoofing detected "
295 "(%02x%02x:%02x%02x:%02x%02x != %02x%02x:%02x%02x:%02x%02x)",
296 req4->SourceMac.B[0], req4->SourceMac.B[1], req4->SourceMac.B[2],
297 req4->SourceMac.B[3], req4->SourceMac.B[4], req4->SourceMac.B[5],
298 From.B[0], From.B[1], From.B[2],
299 From.B[3], From.B[4], From.B[5]
305 switch( ntohs(req4->Request) )
307 case 1: // You want my IP?
308 // Check what type of IP it is
309 switch( req4->SWSize )
312 Log_Debug("ARP", "ARP Request IPv4 Address %i.%i.%i.%i from %i.%i.%i.%i",
313 req4->DestIP.B[0], req4->DestIP.B[1], req4->DestIP.B[2],
315 req4->SourceIP.B[0], req4->SourceIP.B[1],
316 req4->SourceIP.B[2], req4->SourceIP.B[3]);
317 Log_Debug("ARP", " from MAC %02x:%02x:%02x:%02x:%02x:%02x",
318 req4->SourceMac.B[0], req4->SourceMac.B[1],
319 req4->SourceMac.B[2], req4->SourceMac.B[3],
320 req4->SourceMac.B[4], req4->SourceMac.B[5]);
321 iface = IPv4_GetInterface(Adapter, req4->DestIP, 0);
324 ARP_UpdateCache4(req4->SourceIP, req4->SourceMac);
326 req4->DestIP = req4->SourceIP;
327 req4->DestMac = req4->SourceMac;
328 req4->SourceIP = *(tIPv4*)iface->Address;;
329 req4->SourceMac = Adapter->MacAddr;
330 req4->Request = htons(2);
331 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
332 req4->SourceMac.B[0], req4->SourceMac.B[1],
333 req4->SourceMac.B[2], req4->SourceMac.B[3],
334 req4->SourceMac.B[4], req4->SourceMac.B[5]);
335 Link_SendPacket(Adapter, 0x0806, req4->DestMac, sizeof(tArpRequest4), req4);
340 if( Length < (int)sizeof(tArpRequest6) ) {
341 Log_Log("ARP", "Recieved undersized packet (IPv6)");
344 Log_Debug("ARP", "ARP Request IPv6 Address %08x:%08x:%08x:%08x",
345 ntohl(req6->DestIP.L[0]), ntohl(req6->DestIP.L[1]),
346 ntohl(req6->DestIP.L[2]), ntohl(req6->DestIP.L[3])
348 iface = IPv6_GetInterface(Adapter, req6->DestIP, 0);
351 req6->DestIP = req6->SourceIP;
352 req6->DestMac = req6->SourceMac;
353 req6->SourceIP = *(tIPv6*)iface->Address;
354 req6->SourceMac = Adapter->MacAddr;
355 req6->Request = htons(2);
356 Log_Debug("ARP", "Sending back us (%02x:%02x:%02x:%02x:%02x:%02x)",
357 req4->SourceMac.B[0], req4->SourceMac.B[1],
358 req4->SourceMac.B[2], req4->SourceMac.B[3],
359 req4->SourceMac.B[4], req4->SourceMac.B[5]);
360 Link_SendPacket(Adapter, 0x0806, req6->DestMac, sizeof(tArpRequest6), req6);
365 Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
371 case 2: // Ooh! A response!
372 // Check what type of IP it is
373 switch( req4->SWSize )
376 ARP_UpdateCache4( req4->SourceIP, From );
380 if( Length < (int)sizeof(tArpRequest6) ) {
381 Log_Debug("ARP", "Recieved undersized packet (IPv6)");
384 ARP_UpdateCache6( req6->SourceIP, From );
388 Log_Debug("ARP", "Unknown Protocol Address size (%i)", req4->SWSize);
395 Log_Warning("ARP", "Unknown Request ID %i", ntohs(req4->Request));