Unit TCP

Return to Unit Reference

Description

---

Notes:

Segment handling:

Send adds new segments to the end of the list only accepts ACKs for whole segments.

Recv adds/inserts segments in correct SEQ order accepts overlapping segments only sends ACKs for whole segments.

Send will coalesce small data writes into larger segments if options allow this.

Recv will store the segments exactly as received.

TCP Send and Recv do not use a block buffer as per UDP etc. Instead the data for each Segment is stored in memory (TCP_MAX_MSS) allocated with the Segment. The Free and Used values still track the amount of data in the buffer but this method allows OOB data to be handled correctly.

TCP Sequence numbers are compared using modulo 2^32 arithmetic. The following calculations provide the neccessary handling of wraparound etc.

LT = (A - B) < 0

LEQ = (A - B) <= 0

GT = (A - B) > 0

GEQ = (A - B) >= 0

See GlobalSock.pas for actual functions that implement this.

Constants

---

To be documented

Type definitions

---

To be documented

Public variables

---

To be documented

Function declarations

---

Initialization functions

procedure TCPInit;

Description: To be documented

Note	None documented

TCP functions

function CheckTCP(AFamily:Word; ABuffer:Pointer):Boolean;

Description: Verify that the packet is a valid TCP packet

Buffer	The complete packet including Transport header

function GetTCPHeaderOffset(AFamily:Word; ABuffer:Pointer):Word;

Description: To be documented

Buffer	The complete packet including Transport header

function GetTCPHeaderLength(AFamily:Word; ABuffer:Pointer):Word;

Description: TO be documented

Buffer	The complete packet including Transport header

function GetTCPOptionsLength(AFamily:Word; ABuffer:Pointer):Word;

Description: To be documented

Buffer	The complete packet including Transport header

function GetTCPDataOffset(AFamily:Word; ABuffer:Pointer):Word;

Description: To be documented

Buffer	The complete packet including Transport header

function GetTCPDataLength(AFamily:Word; ABuffer:Pointer):Word;

Description: To be documented

Buffer	The complete packet including Transport header

function ChecksumTCPRecv(AFamily:Word; APseudo:PIPPseudo; ABuffer:Pointer; AOffset,ALength:Word):Word;

Description: Validate the Checksum of TCP Pseudo, Header and Data on Receive

Note	None documented

function ChecksumTCPSend(AFamily:Word; APseudo:PIPPseudo; AHeader:PTCPHeader; AOptions,AData:Pointer; AOptionsLength,ADataLength:Word):Word;

Description: Checksum the TCP Pseudo, Header, Options and Data on Send

Note	None documented

Return to Unit Reference