Difference between revisions of "Unit TCP"

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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 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.
+
TCP Sequence numbers are compared using modulo 2^32 arithmetic. The following calculations provide the necessary handling of wraparound etc.
  
 
LT  = (A - B) < 0
 
LT  = (A - B) < 0
Line 85: Line 85:
 
| 65536; TCP Send/Receive Buffer Sizes
 
| 65536; TCP Send/Receive Buffer Sizes
 
|-
 
|-
−
| <code>TCP_WINDOW_SIZE = 16060;</code>
+
| <code>TCP_WINDOW_SIZE = 64240;</code>
−
| 64240; Sliding Window Receive Size (44 x MSS)
+
| Sliding Window Receive Size (44 x MSS)
 
|-
 
|-
 
| <code>TCP_INITIAL_WINDOW = 8192;</code>
 
| <code>TCP_INITIAL_WINDOW = 8192;</code>
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|colspan="2"|&nbsp;  
 
|colspan="2"|&nbsp;  
 
|-
 
|-
−
| <code>TCP_WINDOW_TIMEOUT = 300;</code>
+
| <code>TCP_TIMEOUT_OFFSET = 10;</code>
 +
| How much time offset to allow from the designated value
 +
|-
 +
|colspan="2"|&nbsp;
 +
|-
 +
| <code>TCP_ADVERT_TIMEOUT = 100;</code>
 +
| Time to wait before sending a window size update after closing the receive window
 +
|-
 +
|colspan="2"|&nbsp;
 +
|-
 +
| <code>TCP_WINDOW_TIMEOUT = 5000;</code>
 
| Time to wait before probing small/zero Window
 
| Time to wait before probing small/zero Window
 
|-
 
|-
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|-
 
|-
 
| <code>TCP_HEADER_SIZE = 20;</code>
 
| <code>TCP_HEADER_SIZE = 20;</code>
−
| SizeOf(TTCPHeader); Does Not Allow for Options
+
| SizeOf(TTCPHeader) Does Not Allow for Options
 
|-
 
|-
 
| <code>TCP_OPTIONS_SIZE = 40;</code>
 
| <code>TCP_OPTIONS_SIZE = 40;</code>
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|colspan="2"|&nbsp;
 
|colspan="2"|&nbsp;
 
|-
 
|-
−
| <code>TCP_SEGMENT_SIZE = 48;</code>
+
| <code>TCP_SEGMENT_SIZE = 68;</code>
−
| SizeOf(TTCPSegment)
+
| SizeOf(TTCPSegment) Including TSocketTimerItem
 
|-
 
|-
 
|}
 
|}
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<br />
 
<br />
 
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
 
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
−
<div style="font-size: 14px; padding-left: 12px;">'''TCP socket state constants''' <code> TCP_STATE_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''TCP socket state''' <code> TCP_STATE_* </code></div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
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<br />  
 
<br />  
 
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
 
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
−
<div style="font-size: 14px; padding-left: 12px;">'''TCP header option constants''' <code> TCPOPT_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''TCP header option''' <code> TCPOPT_* </code></div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
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<br />  
 
<br />  
 
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<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
−
<div style="font-size: 14px; padding-left: 12px;">'''TCP header flag constants''' <code> TCP_FLAG_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''TCP header flag''' <code> TCP_FLAG_* </code></div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
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<br />  
 
<br />  
 
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
 
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial; padding-top: 20px; padding-bottom: 15px;">
−
<div style="font-size: 14px; padding-left: 12px;">'''TCP port constants''' <code> TCP_PORT_* </code></div>
+
<div style="font-size: 14px; padding-left: 12px;">'''TCP port''' <code> TCP_PORT_* </code></div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
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----
 
----
  
−
''To be documented''
+
 
 +
'''TCP header'''
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PTCPHeader = ^TTCPHeader;</code>
 +
 
 +
<code>TTCPHeader = packed record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
|colspan="2"|Note: Some TCP definitions are in the Protocol or IP modules
 +
|-
 +
|colspan="2"|Note: 20 Bytes unless TCP Options are added
 +
|-
 +
| <code>SourcePort:Word;</code>
 +
| Network Order
 +
|-
 +
| <code>DestPort:Word;</code>
 +
| Network Order
 +
|-
 +
| <code>Sequence:LongWord;</code>
 +
| First Sequence number in Data
 +
|-
 +
| <code>Acknowledge:LongWord;</code>
 +
| Next Sequence number expected
 +
|-
 +
| <code>HeaderLength:Byte;</code>
 +
| Number of 32 bit words in Header and Options (Bits 4-7 Reserved)
 +
|-
 +
| <code>Flags:Byte;</code>
 +
| Flags for TCP Control (Bits 1-2 Reserved)
 +
|-
 +
| <code>WindowSize:Word;</code>
 +
| Max 65536 (See WindowScale for higher values)
 +
|-
 +
| <code>Checksum:Word;</code>
 +
| As per standard (Header, Options and Data)
 +
|-
 +
| <code>Urgent:Word;</code>
 +
| &nbsp;
 +
|-
 +
|}
 +
</div></div> 
 +
 
 +
'''TCP segment''' 
 +
 
 +
<div class="toccolours mw-collapsible mw-collapsed" style="border: 1; font-family: arial;">
 +
<code>PTCPSegment = ^TTCPSegment;</code>
 +
 
 +
<code>TTCPSegment = record</code>
 +
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 +
{| class="wikitable" style="font-size: 14px; background: white;"
 +
|-
 +
|colspan="2"|Note: 48 Bytes (Used by TCPSendBuffer/TCPRecvBuffer)
 +
|-
 +
| <code>Size:Word;</code>
 +
| Size of Segment Data (Can be zero)
 +
|-
 +
| <code>Data:Pointer;</code>
 +
| Pointer to Data in Buffer (Can be nil)
 +
|-
 +
| <code>FirstSequence:LongWord;</code>
 +
| Start Sequence of Data
 +
|-
 +
| <code>LastSequence:LongWord;</code>
 +
| End Sequence of Data (including Control bits)(actually the Start Sequence of next Segment)
 +
|-
 +
|colspan="2"|&nbsp;
 +
|-
 +
| <code>Control:Word;</code>
 +
| Control Bits on this segment (SYN/FIN/URG) (Send/Recv)
 +
|-
 +
| <code>Transferred:WordBool;</code>
 +
| Data has been Transferred to/from Buffer (Send/Recv)
 +
|-
 +
| <code>Acknowledged:WordBool;</code>
 +
| Data has been Acknowledged (Send/Recv)
 +
|-
 +
| <code>SelectiveAck:WordBool;</code>
 +
| Data has been Selective Acknowledged (Send/Recv)
 +
|-
 +
| <code>RoundTripTime:Int64;</code>
 +
| &nbsp;
 +
|-
 +
|colspan="2"|&nbsp;
 +
|-
 +
| <code>Count:Word;</code>
 +
| Transmit Count (Send)
 +
|-
 +
| <code>Timeout:Int64;</code>
 +
| Transmit (Send)/Acknowledge (Recv) Timeout
 +
|-
 +
| <code>Prev:PTCPSegment;</code>
 +
| Pointer to Prev Segment
 +
|-
 +
| <code>Next:PTCPSegment;</code>
 +
| Pointer to Next Segment
 +
|-
 +
|colspan="2"|&nbsp;
 +
|-
 +
| <code>Item:TSocketTimerItem;</code>
 +
| Socket Timer Item for this Segment
 +
|-
 +
|}
 +
</div></div>
 +
<br />
  
 
=== Class definitions ===
 
=== Class definitions ===
 
----
 
----
  
−
''To be documented''
+
 
 +
'''TCP specific classes'''
 +
 
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPProtocolTransport|<code>TTCPProtocolTransport = class(TProtocolTransport)</code>]]
 +
|-
 +
|}
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPProtocol|<code>TTCPProtocol = class(TNetworkProtocol)</code>]]
 +
|-
 +
|}
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPSocket|<code>TTCPSocket = class(TProtocolSocket)</code>]]
 +
|-
 +
|}
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPState|<code>TTCPState = class(TProtocolState)</code>]]
 +
|-
 +
|}
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPOptions|<code>TTCPOptions = class(TProtocolOptions)</code>]]
 +
|-
 +
|}
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPSendBuffer|<code>TTCPSendBuffer = class(TSocketBuffer)</code>]]
 +
|-
 +
|}
 +
{| class="wikitable" style="font-size: 14px; text-align: left; width: 100%; height: 50px;"
 +
|-
 +
| [[TTCPRecvBuffer|<code>TTCPRecvBuffer = class(TSocketBuffer)</code>]]
 +
|-
 +
|}
 +
<br />
  
 
=== Public variables ===
 
=== Public variables ===
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{| class="wikitable" style="font-size: 14px; background: white;"
−
|-
+
|-https://ultibo.org/wiki/Unit_Sockets#
−
! '''Note'''
+
! Note
 
| None documented
 
| None documented
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Buffer'''
+
! Buffer
 
| The complete packet including Transport header
 
| The complete packet including Transport header
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Buffer'''
+
! Buffer
 
| The complete packet including Transport header
 
| The complete packet including Transport header
 
|-
 
|-
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<pre style="border: 0; padding-bottom:0px;">function GetTCPHeaderLength(AFamily:Word; ABuffer:Pointer):Word;</pre>
 
<pre style="border: 0; padding-bottom:0px;">function GetTCPHeaderLength(AFamily:Word; ABuffer:Pointer):Word;</pre>
−
<div style="font-size: 14px; padding-left: 12px;">'''Description:''' TO be documented</div>
+
<div style="font-size: 14px; padding-left: 12px;">'''Description:''' To be documented</div>
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
<div class="mw-collapsible-content" style="text-align: left; padding-left: 5px;">
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Buffer'''
+
! Buffer
 
| The complete packet including Transport header
 
| The complete packet including Transport header
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Buffer'''
+
! Buffer
 
| The complete packet including Transport header
 
| The complete packet including Transport header
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Buffer'''
+
! Buffer
 
| The complete packet including Transport header
 
| The complete packet including Transport header
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Buffer'''
+
! Buffer
 
| The complete packet including Transport header
 
| The complete packet including Transport header
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Note'''
+
! Note
 
| None documented
 
| None documented
 
|-
 
|-
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{| class="wikitable" style="font-size: 14px; background: white;"
 
|-
 
|-
−
! '''Note'''
+
! Note
 
| None documented
 
| None documented
 
|-
 
|-

Latest revision as of 01:38, 30 May 2018

Return to Unit Reference


Description

Ultibo TCP (Transmission Control Protocol) unit

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 necessary 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


[Expand]
TCP specific constants TCP_*


[Expand]
TCP socket state TCP_STATE_*


[Expand]
TCP header option TCPOPT_*


[Expand]
TCP header flag TCP_FLAG_*


[Expand]
TCP port TCP_PORT_*


Type definitions


TCP header

[Expand]

PTCPHeader = ^TTCPHeader;

TTCPHeader = packed record

TCP segment

[Expand]

PTCPSegment = ^TTCPSegment;

TTCPSegment = record


Class definitions


TCP specific classes

TTCPProtocolTransport = class(TProtocolTransport)
TTCPProtocol = class(TNetworkProtocol)
TTCPSocket = class(TProtocolSocket)
TTCPState = class(TProtocolState)
TTCPOptions = class(TProtocolOptions)
TTCPSendBuffer = class(TSocketBuffer)
TTCPRecvBuffer = class(TSocketBuffer)


Public variables

None defined

Function declarations


Initialization functions

[Expand] 
procedure TCPInit;
Description: To be documented


TCP functions

[Expand] 
function CheckTCP(AFamily:Word; ABuffer:Pointer):Boolean;
Description: Verify that the packet is a valid TCP packet


[Expand] 
function GetTCPHeaderOffset(AFamily:Word; ABuffer:Pointer):Word;
Description: To be documented


[Expand] 
function GetTCPHeaderLength(AFamily:Word; ABuffer:Pointer):Word;
Description: To be documented


[Expand] 
function GetTCPOptionsLength(AFamily:Word; ABuffer:Pointer):Word;
Description: To be documented


[Expand] 
function GetTCPDataOffset(AFamily:Word; ABuffer:Pointer):Word;
Description: To be documented


[Expand] 
function GetTCPDataLength(AFamily:Word; ABuffer:Pointer):Word;
Description: To be documented


[Expand] 
function ChecksumTCPRecv(AFamily:Word; APseudo:PIPPseudo; ABuffer:Pointer; AOffset,ALength:Word):Word;
Description: Validate the Checksum of TCP Pseudo, Header and Data on Receive


[Expand] 
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


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