Kernel - Cleaning up messages
[tpg/acess2.git] / Modules / IPStack / tcp.c
index 3741503..bb71fdb 100644 (file)
@@ -5,8 +5,14 @@
 #define DEBUG  1
 #include "ipstack.h"
 #include "ipv4.h"
+#include "ipv6.h"
 #include "tcp.h"
 
+#define USE_SELECT     1
+#define HEXDUMP_INCOMING       0
+#define HEXDUMP_OUTGOING       0
+#define        CACHE_FUTURE_PACKETS_IN_BYTES   1       // Use a ring buffer to cache out of order packets
+
 #define TCP_MIN_DYNPORT        0xC000
 #define TCP_MAX_HALFOPEN       1024    // Should be enough
 
 #define TCP_RECIEVE_BUFFER_SIZE        0x4000
 
 // === PROTOTYPES ===
-void   TCP_Initialise();
+void   TCP_Initialise(void);
 void   TCP_StartConnection(tTCPConnection *Conn);
 void   TCP_SendPacket(tTCPConnection *Conn, size_t Length, tTCPHeader *Data);
 void   TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffer);
 void   TCP_INT_HandleConnectionPacket(tTCPConnection *Connection, tTCPHeader *Header, int Length);
-void   TCP_INT_AppendRecieved(tTCPConnection *Connection, tTCPStoredPacket *Ptk);
+int    TCP_INT_AppendRecieved(tTCPConnection *Connection, const void *Data, size_t Length);
 void   TCP_INT_UpdateRecievedFromFuture(tTCPConnection *Connection);
 Uint16 TCP_GetUnusedPort();
  int   TCP_AllocatePort(Uint16 Port);
@@ -37,6 +43,8 @@ Uint64        TCP_Client_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buff
 Uint64 TCP_Client_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer);
  int   TCP_Client_IOCtl(tVFS_Node *Node, int ID, void *Data);
 void   TCP_Client_Close(tVFS_Node *Node);
+// --- Helpers
+ int   WrapBetween(Uint32 Lower, Uint32 Value, Uint32 Higher, Uint32 MaxValue);
 
 // === TEMPLATES ===
 tSocketFile    gTCP_ServerFile = {NULL, "tcps", TCP_Server_Init};
@@ -57,11 +65,13 @@ Uint32      gaTCP_PortBitmap[0x800];
  * 
  * Registers the client and server files and the GetPacket callback
  */
-void TCP_Initialise()
+void TCP_Initialise(void)
 {
+       giTCP_NextOutPort += rand()%32;
        IPStack_AddFile(&gTCP_ServerFile);
        IPStack_AddFile(&gTCP_ClientFile);
        IPv4_RegisterCallback(IP4PROT_TCP, TCP_GetPacket);
+       IPv6_RegisterCallback(IP4PROT_TCP, TCP_GetPacket);
 }
 
 /**
@@ -72,22 +82,43 @@ void TCP_Initialise()
  */
 void TCP_SendPacket( tTCPConnection *Conn, size_t Length, tTCPHeader *Data )
 {
-       size_t  buflen;
-       Uint32  *buf;
+       Uint16  checksum[2];
+       
+       Data->Checksum = 0;
+       checksum[1] = htons( ~IPv4_Checksum( (void*)Data, Length ) );   // Partial checksum
+       if(Length & 1)
+               ((Uint8*)Data)[Length] = 0;
+       
+       // TODO: Fragment packet
+       
        switch( Conn->Interface->Type )
        {
-       case 4: // Append IPv4 Pseudo Header
-               buflen = 4 + 4 + 4 + ((Length+1)&~1);
-               buf = malloc( buflen );
-               buf[0] = ((tIPv4*)Conn->Interface->Address)->L;
-               buf[1] = Conn->RemoteIP.v4.L;
-               buf[2] = (htons(Length)<<16) | (6<<8) | 0;
-               Data->Checksum = 0;
-               memcpy( &buf[3], Data, Length );
-               Data->Checksum = IPv4_Checksum( buf, buflen );
-               free(buf);
+       case 4:
+               // Append IPv4 Pseudo Header
+               {
+                       Uint32  buf[3];
+                       buf[0] = ((tIPv4*)Conn->Interface->Address)->L;
+                       buf[1] = Conn->RemoteIP.v4.L;
+                       buf[2] = (htons(Length)<<16) | (6<<8) | 0;
+                       checksum[0] = htons( ~IPv4_Checksum(buf, sizeof(buf)) );        // Partial checksum
+               }
+               Data->Checksum = htons( IPv4_Checksum(checksum, 2*2) ); // Combine the two
                IPv4_SendPacket(Conn->Interface, Conn->RemoteIP.v4, IP4PROT_TCP, 0, Length, Data);
                break;
+               
+       case 6:
+               // Append IPv6 Pseudo Header
+               {
+                       Uint32  buf[4+4+1+1];
+                       memcpy(buf, Conn->Interface->Address, 16);
+                       memcpy(&buf[4], &Conn->RemoteIP, 16);
+                       buf[8] = htonl(Length);
+                       buf[9] = htonl(6);
+                       checksum[0] = htons( ~IPv4_Checksum(buf, sizeof(buf)) );        // Partial checksum
+               }
+               Data->Checksum = htons( IPv4_Checksum(checksum, 2*2) ); // Combine the two
+               IPv6_SendPacket(Conn->Interface, Conn->RemoteIP.v6, IP4PROT_TCP, Length, Data);
+               break;
        }
 }
 
@@ -104,27 +135,10 @@ void TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffe
        tTCPListener    *srv;
        tTCPConnection  *conn;
 
-       Log_Log("TCP", "SourcePort = %i, DestPort = %i",
-               ntohs(hdr->SourcePort), ntohs(hdr->DestPort));
-/*
-       Log_Log("TCP", "SequenceNumber = 0x%x", ntohl(hdr->SequenceNumber));
-       Log_Log("TCP", "AcknowlegementNumber = 0x%x", ntohl(hdr->AcknowlegementNumber));
-       Log_Log("TCP", "DataOffset = %i", hdr->DataOffset >> 4);
-       Log_Log("TCP", "Flags = {");
-       Log_Log("TCP", "  CWR = %B, ECE = %B",
-               !!(hdr->Flags & TCP_FLAG_CWR), !!(hdr->Flags & TCP_FLAG_ECE));
-       Log_Log("TCP", "  URG = %B, ACK = %B",
-               !!(hdr->Flags & TCP_FLAG_URG), !!(hdr->Flags & TCP_FLAG_ACK));
-       Log_Log("TCP", "  PSH = %B, RST = %B",
-               !!(hdr->Flags & TCP_FLAG_PSH), !!(hdr->Flags & TCP_FLAG_RST));
-       Log_Log("TCP", "  SYN = %B, FIN = %B",
-               !!(hdr->Flags & TCP_FLAG_SYN), !!(hdr->Flags & TCP_FLAG_FIN));
-       Log_Log("TCP", "}");
-       Log_Log("TCP", "WindowSize = %i", htons(hdr->WindowSize));
-       Log_Log("TCP", "Checksum = 0x%x", htons(hdr->Checksum));
-       Log_Log("TCP", "UrgentPointer = 0x%x", htons(hdr->UrgentPointer));
-*/
-       Log_Log("TCP", "Flags = %s%s%s%s%s%s",
+       Log_Log("TCP", "TCP_GetPacket: <Local>:%i from [%s]:%i, Flags= %s%s%s%s%s%s%s%s",
+               ntohs(hdr->SourcePort),
+               IPStack_PrintAddress(Interface->Type, Address),
+               ntohs(hdr->DestPort),
                (hdr->Flags & TCP_FLAG_CWR) ? "CWR " : "",
                (hdr->Flags & TCP_FLAG_ECE) ? "ECE " : "",
                (hdr->Flags & TCP_FLAG_URG) ? "URG " : "",
@@ -137,11 +151,14 @@ void TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffe
 
        if( Length > (hdr->DataOffset >> 4)*4 )
        {
+               Log_Log("TCP", "TCP_GetPacket: SequenceNumber = 0x%x", ntohl(hdr->SequenceNumber));
+#if HEXDUMP_INCOMING
                Debug_HexDump(
-                       "[TCP  ] Packet Data = ",
+                       "TCP_GetPacket: Packet Data = ",
                        (Uint8*)hdr + (hdr->DataOffset >> 4)*4,
                        Length - (hdr->DataOffset >> 4)*4
                        );
+#endif
        }
 
        // Check Servers
@@ -155,44 +172,40 @@ void TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffe
                        // Check the destination port
                        if(srv->Port != htons(hdr->DestPort))   continue;
                        
-                       Log_Log("TCP", "Matches server %p", srv);
+                       Log_Log("TCP", "TCP_GetPacket: Matches server %p", srv);
                        // Is this in an established connection?
                        for( conn = srv->Connections; conn; conn = conn->Next )
                        {
-                               Log_Log("TCP", "conn->Interface(%p) == Interface(%p)",
-                                       conn->Interface, Interface);
                                // Check that it is coming in on the same interface
                                if(conn->Interface != Interface)        continue;
 
                                // Check Source Port
-                               Log_Log("TCP", "conn->RemotePort(%i) == hdr->SourcePort(%i)",
+                               Log_Log("TCP", "TCP_GetPacket: conn->RemotePort(%i) == hdr->SourcePort(%i)",
                                        conn->RemotePort, ntohs(hdr->SourcePort));
                                if(conn->RemotePort != ntohs(hdr->SourcePort))  continue;
 
                                // Check Source IP
-                               if(conn->Interface->Type == 6 && !IP6_EQU(conn->RemoteIP.v6, *(tIPv6*)Address))
-                                       continue;
-                               if(conn->Interface->Type == 4 && !IP4_EQU(conn->RemoteIP.v4, *(tIPv4*)Address))
-                                       continue;
+                               if( IPStack_CompareAddress(conn->Interface->Type, &conn->RemoteIP, Address, -1) != 0 )
+                                       continue ;
 
-                               Log_Log("TCP", "Matches connection %p", conn);
+                               Log_Log("TCP", "TCP_GetPacket: Matches connection %p", conn);
                                // We have a response!
                                TCP_INT_HandleConnectionPacket(conn, hdr, Length);
 
                                return;
                        }
 
-                       Log_Log("TCP", "Opening Connection");
+                       Log_Log("TCP", "TCP_GetPacket: Opening Connection");
                        // Open a new connection (well, check that it's a SYN)
                        if(hdr->Flags != TCP_FLAG_SYN) {
-                               Log_Log("TCP", "Packet is not a SYN");
+                               Log_Log("TCP", "TCP_GetPacket: Packet is not a SYN");
                                return ;
                        }
                        
                        // TODO: Check for halfopen max
                        
                        conn = calloc(1, sizeof(tTCPConnection));
-                       conn->State = TCP_ST_HALFOPEN;
+                       conn->State = TCP_ST_SYN_RCVD;
                        conn->LocalPort = srv->Port;
                        conn->RemotePort = ntohs(hdr->SourcePort);
                        conn->Interface = Interface;
@@ -231,7 +244,7 @@ void TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffe
                        srv->ConnectionsTail = conn;
                        if(!srv->NewConnections)
                                srv->NewConnections = conn;
-                       SHORTLOCK(&srv->lConnections);
+                       SHORTREL(&srv->lConnections);
 
                        // Send the SYN ACK
                        hdr->Flags |= TCP_FLAG_ACK;
@@ -268,7 +281,7 @@ void TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffe
                }
        }
        
-       Log_Log("TCP", "No Match");
+       Log_Log("TCP", "TCP_GetPacket: No Match");
 }
 
 /**
@@ -278,18 +291,49 @@ void TCP_GetPacket(tInterface *Interface, void *Address, int Length, void *Buffe
  * \param Length       Length of the packet
  */
 void TCP_INT_HandleConnectionPacket(tTCPConnection *Connection, tTCPHeader *Header, int Length)
-{      
-       tTCPStoredPacket        *pkt;
+{
         int    dataLen;
+       Uint32  sequence_num;
+       
+       // Silently drop once finished
+       // TODO: Check if this needs to be here
+       if( Connection->State == TCP_ST_FINISHED ) {
+               Log_Log("TCP", "Packet ignored - connection finnished");
+               return ;
+       }
        
+       // Syncronise sequence values
        if(Header->Flags & TCP_FLAG_SYN) {
-               Connection->NextSequenceRcv = ntohl(Header->SequenceNumber) + 1;
+               // TODO: What if the packet also has data?
+               Connection->NextSequenceRcv = ntohl(Header->SequenceNumber);
+       }
+       
+       // Ackowledge a sent packet
+       if(Header->Flags & TCP_FLAG_ACK) {
+               // TODO: Process an ACKed Packet
+               Log_Log("TCP", "Conn %p, Sent packet 0x%x ACKed", Connection, Header->AcknowlegementNumber);
        }
        
-       if( Connection->State == TCP_ST_SYN_SENT )
+       // Get length of data
+       dataLen = Length - (Header->DataOffset>>4)*4;
+       Log_Log("TCP", "HandleConnectionPacket - dataLen = %i", dataLen);
+       
+       // 
+       // State Machine
+       //
+       switch( Connection->State )
        {
-               if( (Header->Flags & (TCP_FLAG_SYN|TCP_FLAG_ACK)) == (TCP_FLAG_SYN|TCP_FLAG_ACK) ) {
-                       
+       // Pre-init connection?
+       case TCP_ST_CLOSED:
+               Log_Log("TCP", "Packets to a closed connection?!");
+               break;
+       
+       // --- Init States ---
+       // SYN sent, expecting SYN-ACK Connection Opening
+       case TCP_ST_SYN_SENT:
+               if( Header->Flags & TCP_FLAG_SYN )
+               {
+                       Connection->NextSequenceRcv ++;
                        Header->DestPort = Header->SourcePort;
                        Header->SourcePort = htons(Connection->LocalPort);
                        Header->AcknowlegementNumber = htonl(Connection->NextSequenceRcv);
@@ -297,127 +341,300 @@ void TCP_INT_HandleConnectionPacket(tTCPConnection *Connection, tTCPHeader *Head
                        Header->WindowSize = htons(TCP_WINDOW_SIZE);
                        Header->Flags = TCP_FLAG_ACK;
                        Header->DataOffset = (sizeof(tTCPHeader)/4) << 4;
-                       Log_Log("TCP", "ACKing SYN-ACK");
                        TCP_SendPacket( Connection, sizeof(tTCPHeader), Header );
-                       Connection->State = TCP_ST_OPEN;
+                       
+                       if( Header->Flags & TCP_FLAG_ACK )
+                       {       
+                               Log_Log("TCP", "ACKing SYN-ACK");
+                               Connection->State = TCP_ST_OPEN;
+                       }
+                       else
+                       {
+                               Log_Log("TCP", "ACKing SYN");
+                               Connection->State = TCP_ST_SYN_RCVD;
+                       }
                }
-       }
-       
-       // Get length of data
-       dataLen = Length - (Header->DataOffset>>4)*4;
-       Log_Log("TCP", "HandleConnectionPacket - dataLen = %i", dataLen);
+               break;
        
-       if(Header->Flags & TCP_FLAG_ACK) {
-               // TODO: Process an ACKed Packet
-               Log_Log("TCP", "Conn %p, Packet 0x%x ACKed", Connection, Header->AcknowlegementNumber);
-       }
+       // SYN-ACK sent, expecting ACK
+       case TCP_ST_SYN_RCVD:
+               if( Header->Flags & TCP_FLAG_ACK )
+               {
+                       // TODO: Handle max half-open limit
+                       Connection->State = TCP_ST_OPEN;
+                       Log_Log("TCP", "Connection fully opened");
+               }
+               break;
+               
+       // --- Established State ---
+       case TCP_ST_OPEN:
+               // - Handle State changes
+               //
+               if( Header->Flags & TCP_FLAG_FIN ) {
+                       Log_Log("TCP", "Conn %p closed, recieved FIN", Connection);
+                       VFS_MarkError(&Connection->Node, 1);
+                       Connection->State = TCP_ST_CLOSE_WAIT;
+//                     Header->Flags &= ~TCP_FLAG_FIN;
+                       // CLOSE WAIT requires the client to close (or does it?)
+                       #if 0
+                       
+                       #endif
+               }
        
-       // TODO: Check what to do here
-       if(Header->Flags & TCP_FLAG_FIN) {
-               if( Connection->State == TCP_ST_FIN_SENT ) {
-                       Connection->State = TCP_ST_FINISHED;
+               // Check for an empty packet
+               if(dataLen == 0) {
+                       if( Header->Flags == TCP_FLAG_ACK )
+                       {
+                               Log_Log("TCP", "ACK only packet");
+                               return ;
+                       }
+                       Connection->NextSequenceRcv ++; // TODO: Is this right? (empty packet counts as one byte)
+                       Log_Log("TCP", "Empty Packet, inc and ACK the current sequence number");
+                       Header->DestPort = Header->SourcePort;
+                       Header->SourcePort = htons(Connection->LocalPort);
+                       Header->AcknowlegementNumber = htonl(Connection->NextSequenceRcv);
+                       Header->SequenceNumber = htonl(Connection->NextSequenceSend);
+                       Header->Flags |= TCP_FLAG_ACK;
+                       TCP_SendPacket( Connection, sizeof(tTCPHeader), Header );
                        return ;
                }
-               else {
-                       Connection->State = TCP_ST_FINISHED;
+               
+               // NOTES:
+               // Flags
+               //    PSH - Has Data?
+               // /NOTES
+               
+               sequence_num = ntohl(Header->SequenceNumber);
+               
+               Log_Log("TCP", "0x%08x <= 0x%08x < 0x%08x",
+                       Connection->NextSequenceRcv,
+                       ntohl(Header->SequenceNumber),
+                       Connection->NextSequenceRcv + TCP_WINDOW_SIZE
+                       );
+               
+               // Is this packet the next expected packet?
+               if( sequence_num == Connection->NextSequenceRcv )
+               {
+                        int    rv;
+                       // Ooh, Goodie! Add it to the recieved list
+                       rv = TCP_INT_AppendRecieved(Connection,
+                               (Uint8*)Header + (Header->DataOffset>>4)*4,
+                               dataLen
+                               );
+                       if(rv != 0) {
+                               break;
+                       }
+                       Log_Log("TCP", "0x%08x += %i", Connection->NextSequenceRcv, dataLen);
+                       Connection->NextSequenceRcv += dataLen;
+                       
+                       // TODO: This should be moved out of the watcher thread,
+                       // so that a single lost packet on one connection doesn't cause
+                       // all connections on the interface to lag.
+                       // - Meh, no real issue, as the cache shouldn't be that large
+                       TCP_INT_UpdateRecievedFromFuture(Connection);
+               
+                       // ACK Packet
                        Header->DestPort = Header->SourcePort;
                        Header->SourcePort = htons(Connection->LocalPort);
                        Header->AcknowlegementNumber = htonl(Connection->NextSequenceRcv);
                        Header->SequenceNumber = htonl(Connection->NextSequenceSend);
-                       Header->Flags = TCP_FLAG_ACK;
+                       Header->WindowSize = htons(TCP_WINDOW_SIZE);
+                       Header->Flags &= TCP_FLAG_SYN;  // Eliminate all flags save for SYN
+                       Header->Flags |= TCP_FLAG_ACK;  // Add ACK
+                       Log_Log("TCP", "Sending ACK for 0x%08x", Connection->NextSequenceRcv);
                        TCP_SendPacket( Connection, sizeof(tTCPHeader), Header );
-                       return ;
+                       //Connection->NextSequenceSend ++;
                }
-       }
-       
-       if(dataLen == 0) {
-               Log_Log("TCP", "Empty Packet");
-               return ;
-       }
-       
-       // NOTES:
-       // Flags
-       //    PSH - Has Data?
-       // /NOTES
-       
-       // Allocate and fill cached packet
-       pkt = malloc( dataLen + sizeof(tTCPStoredPacket) );
-       pkt->Next = NULL;
-       pkt->Sequence = ntohl(Header->SequenceNumber);
-       pkt->Length = dataLen;
-       memcpy(pkt->Data, (Uint8*)Header + (Header->DataOffset>>4)*4, dataLen);
+               // Check if the packet is in window
+               else if( WrapBetween(Connection->NextSequenceRcv, sequence_num,
+                               Connection->NextSequenceRcv+TCP_WINDOW_SIZE, 0xFFFFFFFF) )
+               {
+                       Uint8   *dataptr = (Uint8*)Header + (Header->DataOffset>>4)*4;
+                       #if CACHE_FUTURE_PACKETS_IN_BYTES
+                       Uint32  index;
+                        int    i;
+                       
+                       index = sequence_num % TCP_WINDOW_SIZE;
+                       for( i = 0; i < dataLen; i ++ )
+                       {
+                               Connection->FuturePacketValidBytes[index/8] |= 1 << (index%8);
+                               Connection->FuturePacketData[index] = dataptr[i];
+                               // Do a wrap increment
+                               index ++;
+                               if(index == TCP_WINDOW_SIZE)    index = 0;
+                       }
+                       #else
+                       tTCPStoredPacket        *pkt, *tmp, *prev = NULL;
+                       
+                       // Allocate and fill cached packet
+                       pkt = malloc( sizeof(tTCPStoredPacket) + dataLen );
+                       pkt->Next = NULL;
+                       pkt->Sequence = ntohl(Header->SequenceNumber);
+                       pkt->Length = dataLen;
+                       memcpy(pkt->Data, dataptr, dataLen);
+                       
+                       Log_Log("TCP", "We missed a packet, caching",
+                               pkt->Sequence, Connection->NextSequenceRcv);
+                       
+                       // No? Well, let's cache it and look at it later
+                       SHORTLOCK( &Connection->lFuturePackets );
+                       for(tmp = Connection->FuturePackets;
+                               tmp;
+                               prev = tmp, tmp = tmp->Next)
+                       {
+                               if(tmp->Sequence >= pkt->Sequence)      break;
+                       }
+                       
+                       // Add if before first, or sequences don't match 
+                       if( !tmp || tmp->Sequence != pkt->Sequence )
+                       {
+                               if(prev)
+                                       prev->Next = pkt;
+                               else
+                                       Connection->FuturePackets = pkt;
+                               pkt->Next = tmp;
+                       }
+                       // Replace if larger
+                       else if(pkt->Length > tmp->Length)
+                       {
+                               if(prev)
+                                       prev->Next = pkt;
+                               pkt->Next = tmp->Next;
+                               free(tmp);
+                       }
+                       else
+                       {
+                               free(pkt);      // TODO: Find some way to remove this
+                       }
+                       SHORTREL( &Connection->lFuturePackets );
+                       #endif
+               }
+               // Badly out of sequence packet
+               else
+               {
+                       Log_Log("TCP", "Fully out of sequence packet (0x%08x not between 0x%08x and 0x%08x), dropped",
+                               sequence_num, Connection->NextSequenceRcv, Connection->NextSequenceRcv+TCP_WINDOW_SIZE);
+                       // TODO: Spec says we should send an empty ACK with the current state
+               }
+               break;
        
-       // Is this packet the next expected packet?
-       // TODO: Fix this to check if the packet is in the window.
-       if( pkt->Sequence != Connection->NextSequenceRcv )
-       {
-               tTCPStoredPacket        *tmp, *prev = NULL;
+       // --- Remote close states
+       case TCP_ST_CLOSE_WAIT:
                
-               Log_Log("TCP", "Out of sequence packet (0x%08x != 0x%08x)",
-                       pkt->Sequence, Connection->NextSequenceRcv);
+               // Ignore everything, CLOSE_WAIT is terminated by the client
+               Log_Debug("TCP", "CLOSE WAIT - Ignoring packets");
                
-               // No? Well, let's cache it and look at it later
-               SHORTLOCK( &Connection->lFuturePackets );
-               for(tmp = Connection->FuturePackets;
-                       tmp;
-                       prev = tmp, tmp = tmp->Next)
+               break;
+       
+       // LAST-ACK - Waiting for the ACK of FIN (from CLOSE WAIT)
+       case TCP_ST_LAST_ACK:
+               if( Header->Flags & TCP_FLAG_ACK )
                {
-                       if(tmp->Sequence > pkt->Sequence)       break;
+                       Connection->State = TCP_ST_FINISHED;    // Connection completed
+                       Log_Log("TCP", "LAST-ACK to CLOSED - Connection remote closed");
+                       // TODO: Destrory the TCB
+               }
+               break;
+       
+       // --- Local close States
+       case TCP_ST_FIN_WAIT1:
+               if( Header->Flags & TCP_FLAG_FIN )
+               {
+                       Connection->State = TCP_ST_CLOSING;
+                       Log_Debug("TCP", "Conn %p closed, sent FIN and recieved FIN", Connection);
+                       VFS_MarkError(&Connection->Node, 1);
+                       
+                       // ACK Packet
+                       Header->DestPort = Header->SourcePort;
+                       Header->SourcePort = htons(Connection->LocalPort);
+                       Header->AcknowlegementNumber = Header->SequenceNumber;
+                       Header->SequenceNumber = htonl(Connection->NextSequenceSend);
+                       Header->WindowSize = htons(TCP_WINDOW_SIZE);
+                       Header->Flags = TCP_FLAG_ACK;
+                       TCP_SendPacket( Connection, sizeof(tTCPHeader), Header );
+                       break ;
                }
-               if(prev)
-                       prev->Next = pkt;
-               else
-                       Connection->FuturePackets = pkt;
-               pkt->Next = tmp;
-               SHORTREL( &Connection->lFuturePackets );
-       }
-       else
-       {
-               // Ooh, Goodie! Add it to the recieved list
-               TCP_INT_AppendRecieved(Connection, pkt);
-               free(pkt);
-               Log_Log("TCP", "0x%08x += %i", Connection->NextSequenceRcv, dataLen);
-               Connection->NextSequenceRcv += dataLen;
                
-               // TODO: This should be moved out of the watcher thread,
-               // so that a single lost packet on one connection doesn't cause
-               // all connections on the interface to lag.
-               TCP_INT_UpdateRecievedFromFuture(Connection);
-       
-               // ACK Packet
-               Header->DestPort = Header->SourcePort;
-               Header->SourcePort = htons(Connection->LocalPort);
-               Header->AcknowlegementNumber = htonl(Connection->NextSequenceRcv);
-               Header->SequenceNumber = htonl(Connection->NextSequenceSend);
-               Header->WindowSize = htons(TCP_WINDOW_SIZE);
-               Header->Flags &= TCP_FLAG_SYN;  // Eliminate all flags save for SYN
-               Header->Flags |= TCP_FLAG_ACK;  // Add ACK
-               Log_Log("TCP", "Sending ACK for 0x%08x", Connection->NextSequenceRcv);
-               TCP_SendPacket( Connection, sizeof(tTCPHeader), Header );
-               //Connection->NextSequenceSend ++;
+               // TODO: Make sure that the packet is actually ACKing the FIN
+               if( Header->Flags & TCP_FLAG_ACK )
+               {
+                       Connection->State = TCP_ST_FIN_WAIT2;
+                       Log_Debug("TCP", "Conn %p closed, sent FIN ACKed", Connection);
+                       VFS_MarkError(&Connection->Node, 1);
+                       return ;
+               }
+               break;
+       
+       case TCP_ST_FIN_WAIT2:
+               if( Header->Flags & TCP_FLAG_FIN )
+               {
+                       Connection->State = TCP_ST_TIME_WAIT;
+                       Log_Debug("TCP", "FIN sent and recieved, ACKing and going into TIME WAIT %p FINWAIT-2 -> TIME WAIT", Connection);
+                       // Send ACK
+                       Header->DestPort = Header->SourcePort;
+                       Header->SourcePort = htons(Connection->LocalPort);
+                       Header->AcknowlegementNumber = Header->SequenceNumber;
+                       Header->SequenceNumber = htonl(Connection->NextSequenceSend);
+                       Header->WindowSize = htons(TCP_WINDOW_SIZE);
+                       Header->Flags = TCP_FLAG_ACK;
+                       TCP_SendPacket( Connection, sizeof(tTCPHeader), Header );
+               }
+               break;
+       
+       case TCP_ST_CLOSING:
+               // TODO: Make sure that the packet is actually ACKing the FIN
+               if( Header->Flags & TCP_FLAG_ACK )
+               {
+                       Connection->State = TCP_ST_TIME_WAIT;
+                       Log_Debug("TCP", "Conn %p CLOSING -> TIME WAIT", Connection);
+                       VFS_MarkError(&Connection->Node, 1);
+                       return ;
+               }
+               break;
+       
+       // --- Closed (or near closed) states) ---
+       case TCP_ST_TIME_WAIT:
+               Log_Log("TCP", "Packets on Time-Wait, ignored");
+               break;
+       
+       case TCP_ST_FINISHED:
+               Log_Log("TCP", "Packets when CLOSED, ignoring");
+               break;
+       
+       //default:
+       //      Log_Warning("TCP", "Unhandled TCP state %i", Connection->State);
+       //      break;
        }
+       
 }
 
 /**
  * \brief Appends a packet to the recieved list
  * \param Connection   Connection structure
- * \param Pkt  Packet structure on heap
+ * \param Data Packet contents
+ * \param Length       Length of \a Data
  */
-void TCP_INT_AppendRecieved(tTCPConnection *Connection, tTCPStoredPacket *Pkt)
+int TCP_INT_AppendRecieved(tTCPConnection *Connection, const void *Data, size_t Length)
 {
        Mutex_Acquire( &Connection->lRecievedPackets );
-       if(Connection->RecievedBuffer->Length + Pkt->Length > Connection->RecievedBuffer->Space )
+
+       if(Connection->RecievedBuffer->Length + Length > Connection->RecievedBuffer->Space )
        {
-               Log_Error("TCP", "Buffer filled, packet dropped (%s)",
-               //      TCP_INT_DumpConnection(Connection)
-                       ""
+               VFS_MarkAvaliable(&Connection->Node, 1);
+               Log_Error("TCP", "Buffer filled, packet dropped (:%i) - %i + %i > %i",
+                       Connection->LocalPort, Connection->RecievedBuffer->Length, Length,
+                       Connection->RecievedBuffer->Space
                        );
-               return ;
+               Mutex_Release( &Connection->lRecievedPackets );
+               return 1;
        }
        
-       RingBuffer_Write( Connection->RecievedBuffer, Pkt->Data, Pkt->Length );
+       RingBuffer_Write( Connection->RecievedBuffer, Data, Length );
+
+       VFS_MarkAvaliable(&Connection->Node, 1);
        
        Mutex_Release( &Connection->lRecievedPackets );
+       return 0;
 }
 
 /**
@@ -430,27 +647,101 @@ void TCP_INT_AppendRecieved(tTCPConnection *Connection, tTCPStoredPacket *Pkt)
  */
 void TCP_INT_UpdateRecievedFromFuture(tTCPConnection *Connection)
 {
-       tTCPStoredPacket        *pkt, *prev;
+       #if CACHE_FUTURE_PACKETS_IN_BYTES
+        int    i, length = 0;
+       Uint32  index;
+       
+       // Calculate length of contiguous bytes
+       length = Connection->HighestSequenceRcvd - Connection->NextSequenceRcv;
+       index = Connection->NextSequenceRcv % TCP_WINDOW_SIZE;
+       for( i = 0; i < length; i ++ )
+       {
+               if( Connection->FuturePacketValidBytes[i / 8] == 0xFF ) {
+                       i += 7; index += 7;
+                       continue;
+               }
+               else if( !(Connection->FuturePacketValidBytes[i / 8] & (1 << (i%8))) )
+                       break;
+               
+               index ++;
+               if(index > TCP_WINDOW_SIZE)
+                       index -= TCP_WINDOW_SIZE;
+       }
+       length = i;
+       
+       index = Connection->NextSequenceRcv % TCP_WINDOW_SIZE;
+       
+       // Write data to to the ring buffer
+       if( TCP_WINDOW_SIZE - index > length )
+       {
+               // Simple case
+               RingBuffer_Write( Connection->RecievedBuffer, Connection->FuturePacketData + index, length );
+       }
+       else
+       {
+                int    endLen = TCP_WINDOW_SIZE - index;
+               // 2-part case
+               RingBuffer_Write( Connection->RecievedBuffer, Connection->FuturePacketData + index, endLen );
+               RingBuffer_Write( Connection->RecievedBuffer, Connection->FuturePacketData, endLen - length );
+       }
+       
+       // Mark (now saved) bytes as invalid
+       // - Align index
+       while(index % 8 && length)
+       {
+               Connection->FuturePacketData[index] = 0;
+               Connection->FuturePacketData[index/8] &= ~(1 << (index%8));
+               index ++;
+               if(index > TCP_WINDOW_SIZE)
+                       index -= TCP_WINDOW_SIZE;
+               length --;
+       }
+       while( length > 7 )
+       {
+               Connection->FuturePacketData[index] = 0;
+               Connection->FuturePacketValidBytes[index/8] = 0;
+               length -= 8;
+               index += 8;
+               if(index > TCP_WINDOW_SIZE)
+                       index -= TCP_WINDOW_SIZE;
+       }
+       while(length)
+       {
+               Connection->FuturePacketData[index] = 0;
+               Connection->FuturePacketData[index/8] &= ~(1 << (index%8));
+               index ++;
+               if(index > TCP_WINDOW_SIZE)
+                       index -= TCP_WINDOW_SIZE;
+               length --;
+       }
+       
+       #else
+       tTCPStoredPacket        *pkt;
        for(;;)
        {
-               prev = NULL;
-               // Look for the next expected packet in the cache.
                SHORTLOCK( &Connection->lFuturePackets );
-               for(pkt = Connection->FuturePackets;
-                       pkt && pkt->Sequence < Connection->NextSequenceRcv;
-                       prev = pkt, pkt = pkt->Next);
                
-               // If we can't find the expected next packet, stop looking
+               // Clear out duplicates from cache
+               // - If a packet has just been recieved, and it is expected, then
+               //   (since NextSequenceRcv = rcvd->Sequence + rcvd->Length) all
+               //   packets in cache that are smaller than the next expected
+               //   are now defunct.
+               pkt = Connection->FuturePackets;
+               while(pkt && pkt->Sequence < Connection->NextSequenceRcv)
+               {
+                       tTCPStoredPacket        *next = pkt->Next;
+                       free(pkt);
+                       pkt = next;
+               }
+               
+               // If there's no packets left in cache, stop looking
                if(!pkt || pkt->Sequence > Connection->NextSequenceRcv) {
                        SHORTREL( &Connection->lFuturePackets );
                        return;
                }
                
                // Delete packet from future list
-               if(prev)
-                       prev->Next = pkt->Next;
-               else
-                       Connection->FuturePackets = pkt->Next;
+               Connection->FuturePackets = pkt->Next;
                
                // Release list
                SHORTREL( &Connection->lFuturePackets );
@@ -460,6 +751,7 @@ void TCP_INT_UpdateRecievedFromFuture(tTCPConnection *Connection)
                Connection->NextSequenceRcv += pkt->Length;
                free(pkt);
        }
+       #endif
 }
 
 /**
@@ -701,13 +993,12 @@ void TCP_Server_Close(tVFS_Node *Node)
  */
 tVFS_Node *TCP_Client_Init(tInterface *Interface)
 {
-       tTCPConnection  *conn = malloc( sizeof(tTCPConnection) );
+       tTCPConnection  *conn = calloc( sizeof(tTCPConnection) + TCP_WINDOW_SIZE + TCP_WINDOW_SIZE/8, 1 );
 
        conn->State = TCP_ST_CLOSED;
        conn->Interface = Interface;
        conn->LocalPort = -1;
        conn->RemotePort = -1;
-       memset( &conn->RemoteIP, 0, sizeof(conn->RemoteIP) );
 
        conn->Node.ImplPtr = conn;
        conn->Node.NumACLs = 1;
@@ -718,6 +1009,16 @@ tVFS_Node *TCP_Client_Init(tInterface *Interface)
        conn->Node.Close = TCP_Client_Close;
 
        conn->RecievedBuffer = RingBuffer_Create( TCP_RECIEVE_BUFFER_SIZE );
+       #if 0
+       conn->SentBuffer = RingBuffer_Create( TCP_SEND_BUFFER_SIZE );
+       Semaphore_Init(conn->SentBufferSpace, 0, TCP_SEND_BUFFER_SIZE, "TCP SentBuffer", conn->Name);
+       #endif
+       
+       #if CACHE_FUTURE_PACKETS_IN_BYTES
+       // Future recieved data (ahead of the expected sequence number)
+       conn->FuturePacketData = (Uint8*)conn + sizeof(tTCPConnection);
+       conn->FuturePacketValidBytes = conn->FuturePacketData + TCP_WINDOW_SIZE;
+       #endif
 
        SHORTLOCK(&glTCP_OutbountCons);
        conn->Next = gTCP_OutbountCons;
@@ -735,42 +1036,51 @@ tVFS_Node *TCP_Client_Init(tInterface *Interface)
 Uint64 TCP_Client_Read(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
 {
        tTCPConnection  *conn = Node->ImplPtr;
-       char    *destbuf = Buffer;
        size_t  len;
        
        ENTER("pNode XOffset XLength pBuffer", Node, Offset, Length, Buffer);
-       LOG("conn = %p", conn);
-       LOG("conn->State = %i", conn->State);
+       LOG("conn = %p {State:%i}", conn, conn->State);
        
-       // Check if connection is open
-       while( conn->State == TCP_ST_HALFOPEN || conn->State == TCP_ST_SYN_SENT )
+       // Check if connection is estabilishing
+       // - TODO: Sleep instead (maybe using VFS_SelectNode to wait for the
+       //   data to be availiable
+       while( conn->State == TCP_ST_SYN_RCVD || conn->State == TCP_ST_SYN_SENT )
                Threads_Yield();
-       if( conn->State != TCP_ST_OPEN ) {
-               LEAVE('i', 0);
-               return 0;
-       }
        
-       // Poll packets
-       for(;;)
+       // If the conneciton is not open, then clean out the recieved buffer
+       if( conn->State != TCP_ST_OPEN )
        {
-               // Lock list and check if there is a packet
                Mutex_Acquire( &conn->lRecievedPackets );
-               if( conn->RecievedBuffer->Length == 0 ) {
-                       // If not, release the lock, yield and try again
-                       Mutex_Release( &conn->lRecievedPackets );
-                       Threads_Yield();        // TODO: Less expensive wait
-                       continue;
-               }
+               len = RingBuffer_Read( Buffer, conn->RecievedBuffer, Length );
+               Mutex_Release( &conn->lRecievedPackets );
                
-               // Attempt to read all `Length` bytes
-               len = RingBuffer_Read( destbuf, conn->RecievedBuffer, Length );
+               if( len == 0 ) {
+                       VFS_MarkAvaliable(Node, 0);
+                       LEAVE('i', -1);
+                       return -1;
+               }
                
-               // Release the lock (we don't need it any more)
-               Mutex_Release( &conn->lRecievedPackets );
-       
                LEAVE('i', len);
                return len;
        }
+       
+       // Wait
+       VFS_SelectNode(Node, VFS_SELECT_READ|VFS_SELECT_ERROR, NULL, "TCP_Client_Read");
+       
+       // Lock list and read as much as possible (up to `Length`)
+       Mutex_Acquire( &conn->lRecievedPackets );
+       len = RingBuffer_Read( Buffer, conn->RecievedBuffer, Length );
+       
+       if( len == 0 || conn->RecievedBuffer->Length == 0 ) {
+               LOG("Marking as none avaliable (len = %i)", len);
+               VFS_MarkAvaliable(Node, 0);
+       }
+               
+       // Release the lock (we don't need it any more)
+       Mutex_Release( &conn->lRecievedPackets );
+
+       LEAVE('i', len);
+       return len;
 }
 
 /**
@@ -784,7 +1094,7 @@ void TCP_INT_SendDataPacket(tTCPConnection *Connection, size_t Length, void *Dat
        packet->SourcePort = htons(Connection->LocalPort);
        packet->DestPort = htons(Connection->RemotePort);
        packet->DataOffset = (sizeof(tTCPHeader)/4)*16;
-       packet->WindowSize = TCP_WINDOW_SIZE;
+       packet->WindowSize = htons(TCP_WINDOW_SIZE);
        
        packet->AcknowlegementNumber = htonl(Connection->NextSequenceRcv);
        packet->SequenceNumber = htonl(Connection->NextSequenceSend);
@@ -792,6 +1102,11 @@ void TCP_INT_SendDataPacket(tTCPConnection *Connection, size_t Length, void *Dat
        
        memcpy(packet->Options, Data, Length);
        
+       Log_Debug("TCP", "Send sequence 0x%08x", Connection->NextSequenceSend);
+#if HEXDUMP_OUTGOING
+       Debug_HexDump("TCP_INT_SendDataPacket: Data = ", Data, Length);
+#endif
+       
        TCP_SendPacket( Connection, sizeof(tTCPHeader)+Length, packet );
        
        Connection->NextSequenceSend += Length;
@@ -807,21 +1122,39 @@ Uint64 TCP_Client_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buf
        
        ENTER("pNode XOffset XLength pBuffer", Node, Offset, Length, Buffer);
        
+//     #if DEBUG
+//     Debug_HexDump("TCP_Client_Write: Buffer = ",
+//             Buffer, Length);
+//     #endif
+       
        // Check if connection is open
-       while( conn->State == TCP_ST_HALFOPEN || conn->State == TCP_ST_SYN_SENT )
+       while( conn->State == TCP_ST_SYN_RCVD || conn->State == TCP_ST_SYN_SENT )
                Threads_Yield();
+       
        if( conn->State != TCP_ST_OPEN ) {
-               LEAVE('i', 0);
-               return 0;
+               VFS_MarkError(Node, 1);
+               LEAVE('i', -1);
+               return -1;
        }
        
-       while( rem > TCP_MAX_PACKET_SIZE )
+       do
        {
-               TCP_INT_SendDataPacket(conn, TCP_MAX_PACKET_SIZE, Buffer);
-               Buffer += TCP_MAX_PACKET_SIZE;
-       }
-       
-       TCP_INT_SendDataPacket(conn, rem, Buffer);
+                int    len = (rem < TCP_MAX_PACKET_SIZE) ? rem : TCP_MAX_PACKET_SIZE;
+               
+               #if 0
+               // Wait for space in the buffer
+               Semaphore_Signal( &Connection->SentBufferSpace, len );
+               
+               // Save data to buffer (and update the length read by the ammount written)
+               len = RingBuffer_Write( &Connection->SentBuffer, Buffer, len);
+               #endif
+               
+               // Send packet
+               TCP_INT_SendDataPacket(conn, len, Buffer);
+               
+               Buffer += len;
+               rem -= len;
+       } while( rem > 0 );
        
        LEAVE('i', Length);
        return Length;
@@ -850,6 +1183,7 @@ void TCP_StartConnection(tTCPConnection *Conn)
        
        Conn->NextSequenceSend ++;
        Conn->State = TCP_ST_SYN_SENT;
+
        return ;
 }
 
@@ -859,57 +1193,70 @@ void TCP_StartConnection(tTCPConnection *Conn)
 int TCP_Client_IOCtl(tVFS_Node *Node, int ID, void *Data)
 {
        tTCPConnection  *conn = Node->ImplPtr;
+       
+       ENTER("pNode iID pData", Node, ID, Data);
 
        switch(ID)
        {
        case 4: // Get/Set local port
                if(!Data)
-                       return conn->LocalPort;
+                       LEAVE_RET('i', conn->LocalPort);
                if(conn->State != TCP_ST_CLOSED)
-                       return -1;
+                       LEAVE_RET('i', -1);
                if(!CheckMem(Data, sizeof(Uint16)))
-                       return -1;
+                       LEAVE_RET('i', -1);
 
                if(Threads_GetUID() != 0 && *(Uint16*)Data < 1024)
-                       return -1;
+                       LEAVE_RET('i', -1);
 
                conn->LocalPort = *(Uint16*)Data;
-               return 0;
+               LEAVE_RET('i', conn->LocalPort);
 
        case 5: // Get/Set remote port
-               if(!Data)       return conn->RemotePort;
-               if(conn->State != TCP_ST_CLOSED)        return -1;
-               if(!CheckMem(Data, sizeof(Uint16)))     return -1;
+               if(!Data)       LEAVE_RET('i', conn->RemotePort);
+               if(conn->State != TCP_ST_CLOSED)        LEAVE_RET('i', -1);
+               if(!CheckMem(Data, sizeof(Uint16)))     LEAVE_RET('i', -1);
                conn->RemotePort = *(Uint16*)Data;
-               return conn->RemotePort;
+               LEAVE_RET('i', conn->RemotePort);
 
        case 6: // Set Remote IP
                if( conn->State != TCP_ST_CLOSED )
-                       return -1;
+                       LEAVE_RET('i', -1);
                if( conn->Interface->Type == 4 )
                {
-                       if(!CheckMem(Data, sizeof(tIPv4)))      return -1;
+                       if(!CheckMem(Data, sizeof(tIPv4)))      LEAVE_RET('i', -1);
                        conn->RemoteIP.v4 = *(tIPv4*)Data;
                }
                else if( conn->Interface->Type == 6 )
                {
-                       if(!CheckMem(Data, sizeof(tIPv6)))      return -1;
+                       if(!CheckMem(Data, sizeof(tIPv6)))      LEAVE_RET('i', -1);
                        conn->RemoteIP.v6 = *(tIPv6*)Data;
                }
-               return 0;
+               LEAVE_RET('i', 0);
 
        case 7: // Connect
                if(conn->LocalPort == 0xFFFF)
                        conn->LocalPort = TCP_GetUnusedPort();
                if(conn->RemotePort == -1)
-                       return 0;
+                       LEAVE_RET('i', 0);
 
-               TCP_StartConnection(conn);
-               return 1;
+               {
+                       tTime   timeout_end = now() + conn->Interface->TimeoutDelay;
+       
+                       TCP_StartConnection(conn);
+                       // TODO: Wait for connection to open
+                       while( conn->State == TCP_ST_SYN_SENT && timeout_end > now() ) {
+                               Threads_Yield();
+                       }
+                       if( conn->State == TCP_ST_SYN_SENT )
+                               LEAVE_RET('i', 0);
+               }
+
+               LEAVE_RET('i', 1);
        
        // Get recieve buffer length
        case 8:
-               return conn->RecievedBuffer->Length;
+               LEAVE_RET('i', conn->RecievedBuffer->Length);
        }
 
        return 0;
@@ -920,20 +1267,75 @@ void TCP_Client_Close(tVFS_Node *Node)
        tTCPConnection  *conn = Node->ImplPtr;
        tTCPHeader      packet;
        
-       packet.SourcePort = htons(conn->LocalPort);
-       packet.DestPort = htons(conn->RemotePort);
-       packet.DataOffset = (sizeof(tTCPHeader)/4)*16;
-       packet.WindowSize = TCP_WINDOW_SIZE;
+       ENTER("pNode", Node);
        
-       packet.AcknowlegementNumber = 0;
-       packet.SequenceNumber = htonl(conn->NextSequenceSend);
-       packet.Flags = TCP_FLAG_FIN;
+       if( conn->State == TCP_ST_CLOSE_WAIT || conn->State == TCP_ST_OPEN )
+       {
+               packet.SourcePort = htons(conn->LocalPort);
+               packet.DestPort = htons(conn->RemotePort);
+               packet.DataOffset = (sizeof(tTCPHeader)/4)*16;
+               packet.WindowSize = TCP_WINDOW_SIZE;
+               
+               packet.AcknowlegementNumber = 0;
+               packet.SequenceNumber = htonl(conn->NextSequenceSend);
+               packet.Flags = TCP_FLAG_FIN;
+               
+               TCP_SendPacket( conn, sizeof(tTCPHeader), &packet );
+       }
        
-       conn->State = TCP_ST_FIN_SENT;
+       switch( conn->State )
+       {
+       case TCP_ST_CLOSE_WAIT:
+               conn->State = TCP_ST_LAST_ACK;
+               break;
+       case TCP_ST_OPEN:
+               conn->State = TCP_ST_FIN_WAIT1;
+               while( conn->State == TCP_ST_FIN_WAIT1 )        Threads_Yield();
+               break;
+       default:
+               Log_Warning("TCP", "Unhandled connection state in TCP_Client_Close");
+               break;
+       }
        
-       TCP_SendPacket( conn, sizeof(tTCPHeader), &packet );
+       free(conn);
        
-       while( conn->State == TCP_ST_FIN_SENT ) Threads_Yield();
+       LEAVE('-');
+}
+
+/**
+ * \brief Checks if a value is between two others (after taking into account wrapping)
+ */
+int WrapBetween(Uint32 Lower, Uint32 Value, Uint32 Higher, Uint32 MaxValue)
+{
+       if( MaxValue < 0xFFFFFFFF )
+       {
+               Lower %= MaxValue + 1;
+               Value %= MaxValue + 1;
+               Higher %= MaxValue + 1;
+       }
        
-       free(conn);
+       // Simple Case, no wrap ?
+       //       Lower Value Higher
+       // | ... + ... + ... + ... |
+
+       if( Lower < Higher ) {
+               return Lower < Value && Value < Higher;
+       }
+       // Higher has wrapped below lower
+       
+       // Value > Lower ?
+       //       Higher Lower Value
+       // | ... +  ... + ... + ... |
+       if( Value > Lower ) {
+               return 1;
+       }
+       
+       // Value < Higher ?
+       //       Value Higher Lower
+       // | ... + ... +  ... + ... |
+       if( Value < Higher ) {
+               return 1;
+       }
+       
+       return 0;
 }

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