Packages sent and received by the fakewap program

	This file documents the packages sent and received by the fakewap
	program. Fakewap tests a WAP gateway by sending UDP packages
	to make simple requests for WML pages. It is meant for stress
	testing the gateway.

	The basic session looks like this (WTP is the transaction and
	WSP is the session protocol layer):
	
	A)	Fakewap -> Gateway

		WTP: Invoke PDU
		WSP: Connect PDU
	
	B)	Gateway -> Fakewap
	
		WTP: Result PDU
		WSP: ConnectReply PDU
	
	C)	Fakewap -> Gateway
	
		WTP: Ack PDU
	
	D)	Fakewap -> Gateway
	
		WTP: Invoke PDU
		WSP: Get PDU
		
	E)	Gateway -> Fakewap
	
		WTP: Result PDU
		WSP: Reply PDU
		
	F)	Fakewap -> Gateway
	
		WTP: Ack PDU
		
	G)	Fakewap -> Gateway
	
		WTP: Invoke PDU
		WSP: Disconnect PDU

	Packets A-C open a WAP session. Packets D-F fetch a WML page.
	Packet G closes the session.

	The fakewap program does not need to understand the WAP protocols
	as such, it just needs to generate packets in the right order
	with a little variation, and keep track of which packets have
	received and which have not received responses.

	The detailed formats of the packets are listed below. Note
	that bits are numbered in the WAP specification with the
	most significant bit being 0, not 7. Unspecified bits are
	filled in fakewap or the gateway.
	
Packet A)

		bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
	------------+---+---+---+---+---+---+---+---|
	    octet 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 2 | 0 |   |   |   |   |   |   |   |  \    TID, fakewap
	------------+---+---+---+---+---+---+---+---|   |-- generates
	    octet 3 |   |   |   |   |   |   |   |   |  /    linearly
	------------+---+---+---+---+---+---+---+---|
	    octet 4 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 5 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
	------------+---+---+---+---+---+---+---+---|
	    octet 6 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 7 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|

	Fakewap generates a new TID (transaction ID) for each A) packet
	is generates. TIDs are generated linearly. If a 15 bit counter
	overflows, fakewap can, for now, stop sending anything.

Packet B)

		bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
	------------+---+---+---+---+---+---+---+---|
	    octet 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 2 | 1 |   |   |   |   |   |   |   |  \  TID, gateway
	------------+---+---+---+---+---+---+---+---|   | copies from
	    octet 3 |   |   |   |   |   |   |   |   |  /  A) packet
	------------+---+---+---+---+---+---+---+---|
	    octet 4 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 5 |   |   |   |   |   |   |   |   |  \
	------------+---+---+---+---+---+---+---+---|  | Session ID,
	      ...   |   |   |   |   |   |   |   |   |  | generated by
	------------+---+---+---+---+---+---+---+---|  | gateway
	    octet n |   |   |   |   |   |   |   |   |  /
	------------+---+---+---+---+---+---+---+---|
	  octet n+1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	  octet n+2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	
	Fakewap needs to extract the TID and match it to the list of
	A) packets it has sent that have not yet received a B) packet
	in response. It also needs to extract and store the Session
	ID because that is needed by G).
	
	The Session ID is encoded in the uintvar format specified by
	the WSP specification, section 8.1.2 in the WAP 1.1 version.
	Code for decoding it is in gw/wsp.c (should be moved elsewhere).


Packet C) and F)

		bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
	------------+---+---+---+---+---+---+---+---|
	    octet 1 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 2 | 0 |   |   |   |   |   |   |   |  \  TID, must be
	------------+---+---+---+---+---+---+---+---|   | same as in
	    octet 3 |   |   |   |   |   |   |   |   |  /  A) or D) packet.
	------------+---+---+---+---+---+---+---+---|

	Packets C) and F) are identical, except C) gets its TID from
	an A) packet, and F) from a D) packet.

Packet D)

		bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
	------------+---+---+---+---+---+---+---+---|
	    octet 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 2 | 0 |   |   |   |   |   |   |   |  \  TID, fakewap
	------------+---+---+---+---+---+---+---+---|   | generates a
	    octet 3 |   |   |   |   |   |   |   |   |  /  new one
	------------+---+---+---+---+---+---+---+---|
	    octet 4 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 5 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 6 |   |   |   |   |   |   |   |   |  \
	------------+---+---+---+---+---+---+---+---|   |
	      ...   |   |   |   |   |   |   |   |   |   | URI length
	------------+---+---+---+---+---+---+---+---|   |
	    octet n |   |   |   |   |   |   |   |   |  /
	------------+---+---+---+---+---+---+---+---|
	  octet n+1 |   |   |   |   |   |   |   |   |  \
	------------+---+---+---+---+---+---+---+---|   |
	      ...   |   |   |   |   |   |   |   |   |   | URI
	------------+---+---+---+---+---+---+---+---|   |
	  octet n+m |   |   |   |   |   |   |   |   |  /
	------------+---+---+---+---+---+---+---+---|
	
	The URI (or URL) length is specified with uintvar (code to
	generate them also in gw/wsp.c). The URL itself is just the
	octets of the string copied as is.


Packet E)

		bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
	------------+---+---+---+---+---+---+---+---|
	    octet 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 2 | 1 |   |	|   |	|   |	|   |  \  TID, gateway
	------------+---+---+---+---+---+---+---+---|   | copies from
	    octet 3 |   |   |	|   |	|   |	|   |  /  D) packet
	------------+---+---+---+---+---+---+---+---|
	    octet 4 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 5 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
	------------+---+---+---+---+---+---+---+---|
	    octet 7 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 8 |   |   |	|   |	|   |	|   |  \
	------------+---+---+---+---+---+---+---+---|   | Compiled WML
	      ...   |   |   |	|   |	|   |	|   |   | page.
	------------+---+---+---+---+---+---+---+---|   |
	    octet n |   |   |	|   |	|   |	|   |  /
	------------+---+---+---+---+---+---+---+---|
	
	Fakewap needs to extract the TID so it can match it to the
	D) packet it sent. It can ignore the WML page for now.


Packet G)

		bit | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
	------------+---+---+---+---+---+---+---+---|
	    octet 1 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 2 | 0 |   |	|   |	|   |	|   |  \  TID, fakewap
	------------+---+---+---+---+---+---+---+---|   | generates a
	    octet 3 |   |   |	|   |	|   |	|   |  /  new one
	------------+---+---+---+---+---+---+---+---|
	    octet 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
	------------+---+---+---+---+---+---+---+---|
	    octet 5 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 |
	------------+---+---+---+---+---+---+---+---|
	    octet 6 |   |   |	|   |	|   |	|   |  \
	------------+---+---+---+---+---+---+---+---|   | Session ID,
	      ...   |   |   |	|   |	|   |	|   |   | copied from
	------------+---+---+---+---+---+---+---+---|   | B) packet.
	    octet n |   |   |	|   |	|   |	|   |  /
	------------+---+---+---+---+---+---+---+---|