Fixed IPv4 checksum (network byte order, dimwit)

[tpg/acess2.git] / Modules / IPStack / ipv4.c

diff --git a/Modules/IPStack/ipv4.c b/Modules/IPStack/ipv4.c
index b6c7085..31d6f02 100644 (file)
--- a/Modules/IPStack/ipv4.c
+++ b/Modules/IPStack/ipv4.c
@@ -29,7 +29,7 @@ tIPCallback   gaIPv4_Callbacks[256];
 
 // === CODE ===
 /**
- * \fn int IPv4_Initialise()
+ * \brief Initialise the IPv4 Code
  */
 int IPv4_Initialise()
 {
@@ -39,8 +39,9 @@ int IPv4_Initialise()
 }
 
 /**
- * \fn int IPv4_RegisterCallback( int ID, tIPCallback Callback )
  * \brief Registers a callback
+ * \param ID   8-bit packet type ID
+ * \param Callback     Callback function
  */
 int IPv4_RegisterCallback(int ID, tIPCallback Callback)
 {
@@ -58,6 +59,7 @@ int IPv4_RegisterCallback(int ID, tIPCallback Callback)
  * \param ID   Some random ID number
  * \param Length       Data Length
  * \param Data Packet Data
+ * \return Boolean Success
  */
 int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, const void *Data)
 {
@@ -67,15 +69,13 @@ int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int
        tIPv4Header     *hdr = (void*)buf;
         int    ret;
        
-       // TODO: OUTPUT Firewall rule go here
+       // OUTPUT Firewall rule go here
        ret = IPTablesV4_TestChain("OUTPUT",
-               &Iface->IP4.Address, &Address,
+               (tIPv4*)Iface->Address, &Address,
                Protocol, 0,
                Length, Data);
-       
-       if(ret != 0)
-       {
-               // Just drop it
+       if(ret != 0) {
+               // Just drop it (with an error)
                return 0;
        }
        
@@ -95,7 +95,7 @@ int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int
        hdr->TTL = DEFAULT_TTL;
        hdr->Protocol = Protocol;
        hdr->HeaderChecksum = 0;        // Will be set later
-       hdr->Source = Iface->IP4.Address;
+       hdr->Source = *(tIPv4*)Iface->Address;
        hdr->Destination = Address;
        hdr->HeaderChecksum = IPv4_Checksum(hdr, sizeof(tIPv4Header));
        
@@ -123,14 +123,14 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
        //Log_Log("IPv4", "Version = %i", hdr->Version);
        //Log_Log("IPv4", "HeaderLength = %i", hdr->HeaderLength);
        //Log_Log("IPv4", "DiffServices = %i", hdr->DiffServices);
-       Log_Log("IPv4", "TotalLength = %i", ntohs(hdr->TotalLength) );
+       Log_Debug("IPv4", "TotalLength = %i", ntohs(hdr->TotalLength) );
        //Log_Log("IPv4", "Identifcation = %i", ntohs(hdr->Identifcation) );
        //Log_Log("IPv4", "TTL = %i", hdr->TTL );
-       Log_Log("IPv4", "Protocol = %i", hdr->Protocol );
+       Log_Debug("IPv4", "Protocol = %i", hdr->Protocol );
        //Log_Log("IPv4", "HeaderChecksum = 0x%x", ntohs(hdr->HeaderChecksum) );
-       Log_Log("IPv4", "Source = %i.%i.%i.%i",
+       Log_Debug("IPv4", "Source = %i.%i.%i.%i",
                hdr->Source.B[0], hdr->Source.B[1], hdr->Source.B[2], hdr->Source.B[3] );
-       Log_Log("IPv4", "Destination = %i.%i.%i.%i",
+       Log_Debug("IPv4", "Destination = %i.%i.%i.%i",
                hdr->Destination.B[0], hdr->Destination.B[1],
                hdr->Destination.B[2], hdr->Destination.B[3] );
        #endif  
@@ -142,7 +142,17 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
        }
        
        // Check Header checksum
-       //TODO
+       {
+               Uint16  hdrVal, compVal;
+               hdrVal = hdr->HeaderChecksum;
+               hdr->HeaderChecksum = 0;
+               compVal = IPv4_Checksum(hdr, hdr->HeaderLength);
+               if(hdrVal != compVal) {
+                       Log_Log("IPv4", "Header checksum fails (%04x != %04x)", hdrVal, compVal);
+                       return ;
+               }
+               hdr->HeaderChecksum = hdrVal;
+       }
        
        // Check Packet length
        if( ntohs(hdr->TotalLength) > Length) {
@@ -150,9 +160,9 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
                return;
        }
        
-       
        // TODO: Handle packet fragmentation
        
+       
        // Get Data and Data Length
        dataLength = ntohs(hdr->TotalLength) - sizeof(tIPv4Header);
        data = &hdr->Options[0];
@@ -160,8 +170,9 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
        // Get Interface (allowing broadcasts)
        iface = IPv4_GetInterface(Adapter, hdr->Destination, 1);
        
-       // TODO: INPUT Firewall Rule
+       // Firewall rules
        if( iface ) {
+               // Incoming Packets
                ret = IPTablesV4_TestChain("INPUT",
                        &hdr->Source, &hdr->Destination,
                        hdr->Protocol, 0,
@@ -169,6 +180,7 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
                        );
        }
        else {
+               // Routed packets
                ret = IPTablesV4_TestChain("FORWARD",
                        &hdr->Source, &hdr->Destination,
                        hdr->Protocol, 0,
@@ -180,7 +192,9 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
        // 0 - Allow
        case 0: break;
        // 1 - Silent Drop
-       case 1: return ;
+       case 1:
+               Log_Debug("IPv4", "Silently dropping packet");
+               return ;
        // Unknown, silent drop
        default:
                return ;
@@ -189,7 +203,7 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
        // Routing
        if(!iface)
        {
-               Log_Log("IPv4", "Route the packet");
+               Log_Debug("IPv4", "Route the packet");
                
                // TODO: Parse Routing tables and determine where to send it
                
@@ -198,7 +212,7 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
        
        // Send it on
        if( gaIPv4_Callbacks[hdr->Protocol] )
-               gaIPv4_Callbacks[hdr->Protocol] (iface, &hdr->Source, dataLength, data);
+               gaIPv4_Callbacks[hdr->Protocol]( iface, &hdr->Source, dataLength, data );
        else
                Log_Log("IPv4", "Unknown Protocol %i", hdr->Protocol);
 }
@@ -206,6 +220,9 @@ void IPv4_int_GetPacket(tAdapter *Adapter, tMacAddr From, int Length, void *Buff
 /**
  * \fn tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address)
  * \brief Searches an adapter for a matching address
+ * \param Adapter      Incoming Adapter
+ * \param Address      Destination Address
+ * \param Broadcast    Allow broadcast packets
  */
 tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 {
@@ -219,15 +236,15 @@ tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
        {
                if( iface->Adapter != Adapter ) continue;
                if( iface->Type != 4 )  continue;
-               if( IP4_EQU(Address, iface->IP4.Address) )
+               if( IP4_EQU(Address, *(tIPv4*)iface->Address) )
                        return iface;
                
                if( !Broadcast )        continue;
                
-               this = ntohl( iface->IP4.Address.L );
+               this = ntohl( ((tIPv4*)iface->Address)->L );
                
                // Check for broadcast
-               netmask = IPv4_Netmask(iface->IP4.SubnetBits);
+               netmask = IPv4_Netmask(iface->SubnetBits);
                
                if( (addr & netmask) == (this & netmask)
                 && (addr & ~netmask) == (0xFFFFFFFF & ~netmask) )
@@ -238,6 +255,7 @@ tInterface *IPv4_GetInterface(tAdapter *Adapter, tIPv4 Address, int Broadcast)
 
 /**
  * \brief Convert a network prefix to a netmask
+ * \param FixedBits    Netmask size (/n)
  * 
  * For example /24 will become 255.255.255.0
  */
@@ -252,6 +270,10 @@ Uint32 IPv4_Netmask(int FixedBits)
 
 /**
  * \brief Calculate the IPv4 Checksum
+ * \param Buf  Input buffer
+ * \param Size Size of input
+ * 
+ * One's complement sum of all 16-bit words (bitwise inverted)
  */
 Uint16 IPv4_Checksum(const void *Buf, int Size)
 {
@@ -262,17 +284,20 @@ Uint16 IPv4_Checksum(const void *Buf, int Size)
        Size = (Size + 1) >> 1; // 16-bit word count
        for(i = 0; i < Size; i++ )
        {
-               if((int)sum + arr[i] > 0xFFFF)
+               Uint16  val = ntohs(arr[i]);
+               if((int)sum + val > 0xFFFF)
                        sum ++; // Simulate 1's complement
-               sum += arr[i];
+               sum += val;
        }
        return ~sum ;
 }
 
 /**
  * \brief Sends an ICMP Echo and waits for a reply
+ * \param IFace        Interface
+ * \param Addr Destination address
  */
-int IPv4_Ping(tInterface *Iface, tIPv4 Addr)
+int IPv4_Ping(tInterface *IFace, tIPv4 Addr)
 {
-       return ICMP_Ping(Iface, Addr);
+       return ICMP_Ping(IFace, Addr);
 }