3 * - Link/Media Layer Interface
9 #define MAX_PACKET_SIZE 2048
12 void Link_RegisterType(Uint16 Type, tPacketCallback Callback);
14 Uint32 Link_CalculateCRC(void *Data, int Length);
15 void Link_SendPacket(tAdapter *Adapter, Uint16 Type, tMacAddr To, int Length, void *Buffer);
16 void Link_WatchDevice(tAdapter *Adapter);
19 int giRegisteredTypes = 0;
20 int giRegisteredTypeSpace = 0;
23 tPacketCallback Callback;
25 int gbLink_CRCTableGenerated = 0;
26 Uint32 gaiLink_CRCTable[256];
30 * \fn void Link_RegisterType(Uint16 Type, tPacketCallback Callback)
31 * \brief Registers a callback for a specific packet type
33 * \todo Make thread safe (place a mutex on the list)
35 void Link_RegisterType(Uint16 Type, tPacketCallback Callback)
40 Type = htons(Type); // Set to network order
42 for( i = giRegisteredTypes; i -- ; )
44 if(gaRegisteredTypes[i].Type == Type) {
45 Log_Warning("NET", "Attempt to register 0x%x twice", Type);
49 if(gaRegisteredTypes[i].Callback == NULL) break;
54 giRegisteredTypeSpace += 5;
55 tmp = realloc(gaRegisteredTypes, giRegisteredTypeSpace*sizeof(*gaRegisteredTypes));
58 "Out of heap space! (Attempted to allocate %i)",
59 giRegisteredTypeSpace*sizeof(*gaRegisteredTypes)
63 gaRegisteredTypes = tmp;
64 i = giRegisteredTypes;
68 gaRegisteredTypes[i].Callback = Callback;
69 gaRegisteredTypes[i].Type = Type;
73 * \fn void Link_SendPacket(tAdapter *Adapter, Uint16 Type, tMacAddr To, int Length, void *Buffer)
74 * \brief Formats and sends a packet on the specified interface
76 void Link_SendPacket(tAdapter *Adapter, Uint16 Type, tMacAddr To, int Length, void *Buffer)
78 int bufSize = sizeof(tEthernetHeader) + ((Length+3)&~3) + 4;
79 Uint8 buf[bufSize]; // dynamic stack arrays ftw!
80 tEthernetHeader *hdr = (void*)buf;
82 Log_Log("NET", "Sending %i bytes to %02x:%02x:%02x:%02x:%02x:%02x (Type 0x%x)",
83 Length, To.B[0], To.B[1], To.B[2], To.B[3], To.B[4], To.B[5], Type);
86 hdr->Src = Adapter->MacAddr;
87 hdr->Type = htons(Type);
89 memcpy(hdr->Data, Buffer, Length);
91 *(Uint32*) &hdr->Data[bufSize-4] = 0;
92 *(Uint32*) &hdr->Data[bufSize-4] = htonl( Link_CalculateCRC(buf, bufSize) );
94 VFS_Write(Adapter->DeviceFD, bufSize, buf);
98 * \fn void Link_WatchDevice(tAdapter *Adapter)
99 * \brief Spawns a worker thread to watch the specified adapter
101 void Link_WatchDevice(tAdapter *Adapter)
103 int tid = Proc_SpawnWorker(); // Create a new worker thread
106 Log_Warning("NET", "Unable to create watcher thread for '%s'", Adapter->Device);
111 Log_Log("NET", "Watching '%s' using tid %i", Adapter->Device, tid);
115 if( !gbLink_CRCTableGenerated )
119 while(Adapter->DeviceFD != -1)
121 Uint8 buf[MAX_PACKET_SIZE];
122 tEthernetHeader *hdr = (void*)buf;
126 // Wait for a packet (Read on a network device is blocking)
127 ret = VFS_Read(Adapter->DeviceFD, MAX_PACKET_SIZE, buf);
130 if(ret <= (int)sizeof(tEthernetHeader)) {
131 Log_Log("NET", "Recieved an undersized packet");
135 Log_Log("NET", "Packet from %02x:%02x:%02x:%02x:%02x:%02x",
136 hdr->Src.B[0], hdr->Src.B[1], hdr->Src.B[2],
137 hdr->Src.B[3], hdr->Src.B[4], hdr->Src.B[5]
139 Log_Log("NET", "to %02x:%02x:%02x:%02x:%02x:%02x",
140 hdr->Dest.B[0], hdr->Dest.B[1], hdr->Dest.B[2],
141 hdr->Dest.B[3], hdr->Dest.B[4], hdr->Dest.B[5]
143 checksum = *(Uint32*)&hdr->Data[ret-sizeof(tEthernetHeader)-4];
144 Log_Log("NET", "Checksum 0x%08x", checksum);
146 // Check if there is a registered callback for this packet type
147 for( i = giRegisteredTypes; i--; )
149 if(gaRegisteredTypes[i].Type == hdr->Type) break;
153 Log_Log("NET", "Unregistered type 0x%x", ntohs(hdr->Type));
158 gaRegisteredTypes[i].Callback(
161 ret - sizeof(tEthernetHeader),
166 Log_Log("NET", "Watcher terminated (file closed)");
171 // From http://www.cl.cam.ac.uk/research/srg/bluebook/21/crc/node6.html
172 #define QUOTIENT 0x04c11db7
173 void Link_InitCRC(void)
178 for (i = 0; i < 256; i++)
181 for (j = 0; j < 8; j++)
183 if (crc & 0x80000000)
184 crc = (crc << 1) ^ QUOTIENT;
188 gaiLink_CRCTable[i] = crc;
191 gbLink_CRCTableGenerated = 1;
194 Uint32 Link_CalculateCRC(void *Data, int Length)
196 // x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1
201 if(Length < 4) return 0;
203 result = *data++ << 24;
204 result |= *data++ << 16;
205 result |= *data++ << 8;
210 for( i = 0; i < Length; i++ )
212 result = (result << 8 | *data++) ^ gaiLink_CRCTable[result >> 24];