Modules/IPStack - Abstract TCP checksums to allow verifcation

diff --git a/KernelLand/Modules/IPStack/tcp.c b/KernelLand/Modules/IPStack/tcp.c
index ac58ec3..bbf7951 100644 (file)
--- a/KernelLand/Modules/IPStack/tcp.c
+++ b/KernelLand/Modules/IPStack/tcp.c
@@ -107,14 +107,42 @@ void TCP_SendPacket( tTCPConnection *Conn, tTCPHeader *Header, size_t Length, co
        TCP_int_SendPacket(Conn->Interface, &Conn->RemoteIP, Header, Length, Data);
 }
 
-void TCP_int_SendPacket(tInterface *Interface, const void *Dest, tTCPHeader *Header, size_t Length, const void *Data )
+Uint16 TCP_int_CalculateChecksum(int AddrType, const void *LAddr, const void *RAddr,
+       size_t HeaderLength, const tTCPHeader *Header, size_t DataLength, const void *Data)
 {
-       tIPStackBuffer  *buffer;
+       size_t packlen = HeaderLength + DataLength;
        Uint16  checksum[3];
-        int    packlen = sizeof(*Header) + Length;
-       
-       buffer = IPStack_Buffer_CreateBuffer(2 + IPV4_BUFFERS);
-       if( Data && Length )
+
+       switch(AddrType)
+       {
+       case 4: {
+               Uint32  buf[3];
+               buf[0] = ((tIPv4*)LAddr)->L;
+               buf[1] = ((tIPv4*)RAddr)->L;
+               buf[2] = htonl( (packlen) | (IP4PROT_TCP<<16) | (0<<24) );
+               checksum[0] = htons( ~IPv4_Checksum(buf, sizeof(buf)) );        // Partial checksum
+               break; }
+       case 6: {
+               Uint32  buf[4+4+1+1];
+               memcpy(&buf[0], LAddr, 16);
+               memcpy(&buf[4], RAddr, 16);
+               buf[8] = htonl(packlen);
+               buf[9] = htonl(IP4PROT_TCP);
+               checksum[0] = htons( ~IPv4_Checksum(buf, sizeof(buf)) );        // Partial checksum
+               break; }
+       default:
+               return 0;
+       }
+       checksum[1] = htons( ~IPv4_Checksum(Header, HeaderLength) );
+       checksum[2] = htons( ~IPv4_Checksum(Data, DataLength) );
+
+       return htons( IPv4_Checksum(checksum, sizeof(checksum)) );
+}
+
+void TCP_int_SendPacket(tInterface *Interface, const void *Dest, tTCPHeader *Header, size_t Length, const void *Data )
+{
+       tIPStackBuffer  *buffer = IPStack_Buffer_CreateBuffer(2 + IPV4_BUFFERS);
+       if( Length > 0 )
                IPStack_Buffer_AppendSubBuffer(buffer, Length, 0, Data, NULL, NULL);
        IPStack_Buffer_AppendSubBuffer(buffer, sizeof(*Header), 0, Header, NULL, NULL);
 
@@ -124,38 +152,17 @@ void TCP_int_SendPacket(tInterface *Interface, const void *Dest, tTCPHeader *Hea
                );
 
        Header->Checksum = 0;
-       checksum[1] = htons( ~IPv4_Checksum(Header, sizeof(tTCPHeader)) );
-       checksum[2] = htons( ~IPv4_Checksum(Data, Length) );
+       Header->Checksum = TCP_int_CalculateChecksum(Interface->Type, Interface->Address, Dest,
+               sizeof(tTCPHeader), Header, Length, Data);
        
        // TODO: Fragment packet
        
        switch( Interface->Type )
        {
        case 4:
-               // Get IPv4 pseudo-header checksum
-               {
-                       Uint32  buf[3];
-                       buf[0] = ((tIPv4*)Interface->Address)->L;
-                       buf[1] = ((tIPv4*)Dest)->L;
-                       buf[2] = htonl( (packlen) | (IP4PROT_TCP<<16) | (0<<24) );
-                       checksum[0] = htons( ~IPv4_Checksum(buf, sizeof(buf)) );        // Partial checksum
-               }
-               // - Combine checksums
-               Header->Checksum = htons( IPv4_Checksum(checksum, sizeof(checksum)) );
                IPv4_SendPacket(Interface, *(tIPv4*)Dest, IP4PROT_TCP, 0, buffer);
                break;
-               
        case 6:
-               // Append IPv6 Pseudo Header
-               {
-                       Uint32  buf[4+4+1+1];
-                       memcpy(buf, Interface->Address, 16);
-                       memcpy(&buf[4], Dest, 16);
-                       buf[8] = htonl(packlen);
-                       buf[9] = htonl(IP4PROT_TCP);
-                       checksum[0] = htons( ~IPv4_Checksum(buf, sizeof(buf)) );        // Partial checksum
-               }
-               Header->Checksum = htons( IPv4_Checksum(checksum, sizeof(checksum)) );  // Combine the two
                IPv6_SendPacket(Interface, *(tIPv6*)Dest, IP4PROT_TCP, buffer);
                break;
        }