PPP-Blinky - Small Internet Protocol Stack using a standard se…

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Nicolas Nackel / Mbed 2 deprecated PPP-Blinky

Small Internet Protocol Stack using a standard serial port.

PPP-Blinky - TCP/IP Networking Over a Serial Port

Note: The source code is at the bottom of this page.

/media/uploads/nixnax/blinky-connected.gif
A Windows desktop showing PPP-Blinky in the network connections list.

Describe PPP-Blinky in Three Sentences

PPP-Blinky is a tiny library that enables Internet protocols (IPv4) to any mbed target hardware by using only a serial port.

The code runs on processors with as little as 8k RAM, for example the Nucleo-L053R8 board.

PPP-Blinky uses the industry-standard PPP (Point-to-Point) Protocol and a tiny "stateless" TCP/IP stack.

No Ethernet Port Required

No ethernet port is required - PPP-Blinky uses a serial port to send IP packets to your PC.

PPP-Blinky emulates a standard dial-up modem and therefore connects to Windows, Linux or Adroid machines.

The code runs on most ARM mbed platforms such as the LPC11U24 shown in the picture below:

/media/uploads/nixnax/blinky-to-laptop1.jpg mbed LPC11u24 acting as a webserver to a Windows laptop.

Webserver

The Webserver and WebSocket functions are ideal for building browser-based GUIs on mbed-enabled hardware.

PPP-Blinky's HTTP webserver works with most web clients such as Internet Explorer, Mozilla Firefox, Google Chrome, Safari, Curl, wget and Lynx as well as Microsoft Powershell Invoke-Webrequest command.

In the image below Firefox web browser displays the main web page embedded into PPP-Blinky's code:

/media/uploads/nixnax/ppp-blinky-firefox.jpg Firefox web browser displays a web page embedded into PPP-Blinky's code

WebSocket Service

WebSocket is the most popular protocol standard for real-time bidirectional TCP/IP communication between clients and servers.
In the image below a small Internet Explorer script has connected to PPP-Blinky's WebSocket Service.
A websocket message was then sent by the browser and was echoed back by the WebSocket, triggering the onmessage event in the script.
The WebSocket service enables bidirectional real-time interaction between PPP-Blinky and any element in the browser DOM via JavaScript.
If you already have PPP-Blinky up and running you can test your WebSocket service using this: http://jsfiddle.net/d26cyuh2/112/embedded/result
Websockets are ideal for building browser-based GUIs for mbed hardware.

/media/uploads/nixnax/ppp-blinky-websocke-2.gif

Trying PPP-Blinky on your mbed board

You will need an mbed-enabled hardware board: https://developer.mbed.org/platforms/

Establish a serial port connection between your host PC and your mbed board. The easiest way is to use mbed hardware with a USB serial debug port. I've tried the ST-Micro Nucleo-L476RG, Nucleo-L152RE, Nucleo-F401RE, Nucleo-L432KC, Nucleo-L053R8, mbed-LPC11U24 and mbed-LPC1768 boards and they all work out of the box. Use the mbed online compiler to compile the software for your target board. Save the compiled binary to your hardware.

Before establishing a network connection, you can verify the operation of the code by opening a terminal program such as Tera Term, and setting the baud rate of the COM port on your mbed board to 115200 baud. LED1 should toggle for every two 0x7E (~) (i.e. tilde) characters you type, as 0x7E is the PPP frame start/end marker. Don't forget to close the port when your'e done testing, or else Windows Dial-up Networking will report that the COM port is in use by another program when you try to connect.

Once you are certain that the serial port and firmware is working, proceed to creating a new network connection on your PC -see below.

Creating a Dial-up Connection in Windows

/media/uploads/nixnax/modem.jpg

Setting up Dial-Up Networking (DUN) on your Windows 7 or 8 PC is essentially a two-step process: First, you create a new modem device, because PPP-blinky partially emulates a standard Windows serial port modem device. Second, you create a new Internet connection (in practice, a new network adapter) which is associated with your new "modem".

Step-by-step description of how to configure Windows for PPP-Blinky here:

/users/nixnax/code/PPP-Blinky/wiki/Configuring-Windows-Dial-Up-Networking

There is also a screen on how to set up Linux dial-up networking near the bottom of this page.

Connecting to PPP-Blinky from your PC

Once Windows networking is configured you can establish a dial-up connection to your mbed board over the USB virtual com port.

The IP address you manually assigned to the new dial-up network adapter (172.10.10.1) functions as a gateway to any valid IP address on that subnet. In the screen capture below, I'm sending pings from the Windows 8 command line to my ST-Micro Nucleo-L476RG board over the USB virtual serial Port. I'm also using a second serial port and Tera Term to capture the debug output from a second serial port on the hardware. The optional debug output from the board prints out the IP source and destination address and the first few bytes of the data payload. Note that the source is the adapter IP address, (172.10.10.1 in this case) and the destination is some other address on that subnet - all packets to the subnet are sent to our mbed hardware. For example, you could also ping 172.10.10.123 or, if your PPP-Blinky is running, simply click on this link: http://172.10.10.123

/media/uploads/nixnax/ping-cap-3.gif

One Million Pings!

In the image below the ICMP ("ping") echo reply service was tested by sending one million pings to ppp-Blinky. This took over two hours.
The ping tool used on the Windows 8 PC was psping.exe from PsTools by Mark Russinovich - http://bit.ly/PingFast
The average reply time for a short ping (1 byte of payload data) was 11 milliseconds at 115200 baud on the $10 Nucleo-L053R8 board - barely enough time for 130 bytes to be sent over the port!

/media/uploads/nixnax/ppp-blinky-ping-results.jpg

Monitoring PPP-Blinky Packets

The image below is from a Microsoft Network Monitor 3.4 capture session.

Responses from PPP-Blinky are shown in blue.

Frame 2 - Internet Explorer at IP 172.10.10.1 (the Dial-Up Adapter IP) requests a TCP connection by sending an S (SYN) flag.
Frame 3 - PPP-Blinky at IP 172.10.10.2 responds with an ACK in frame 3. One direction of the link is now established.
Frame 4 - The PC acknowledges the SYN sent by PPP-Blinky in frame 3. The TCP link is now fully established.
Frame 5 - The browser "pushes" (P flag is set) an HTTP GET request to PPP-Blinky.
Frame 6 - PPP-Blinky responds with a standard HTTP response "pushes" (P flag set) back a small web page. It also sets the A (ACK) flag to acknowledge the message sent in frame 6.
Frame 7 - The PC acknowledges reception of the HTTP payload.
Frame 8 - The PC starts to shut down the TCP connection by sending a FIN flag.
Frame 9 - PPP-Blinky acknowledges the FIN request - the connection is now closed in one direction. It also sets a FIN flag in the response to request closure of the opposite direction of the connection.
Frame 10 - The PC acknowledges the FIN request. The closing of the TCP connection is now confirmed in both directions.

/media/uploads/nixnax/ms-network-monitor-http-get-1.gif

Debug Output

PPP-Blinky can output handy debug information to an optional second serial port.
The image below shows the debug output (Ident, Source, Destination, TCP Flags) for a complete HTTP conversation.
The PC messages are displayed in black. PPP-Blinky messages are blue.
Notice how PPP-blinky automatically inserts a blank line after each full HTTP conversation.

/media/uploads/nixnax/tcp-data-3.gif

Creating a Dial-Up Connection in Linux

The screen below shows the required pppd command to connect to PPP-Blinky from a Linux machine. This was much simpler than Windows! The USB serial port of the mbed LPC1768 board registered as /dev/ttyACM0 on my Linux box. Do a websearch on pppd if you want to learn more about pppd, the Linux PPP handler. Near the bottom of the screen below, two webpages are fetched (/ and /y) by using the curl command on the command line. Gnome Webkit and Firefox work fine, too. Also try echo GET / HTTP/1.1 | nc 172.10.10.2 which uses netcat, the "Swiss army knife" of networking tools. PPP-Blinky was also tested with ApacheBench, the Apache server benchmark software. After 100000 fetches, the mean page fetch rate was reported as 6 page fetches per second for a small page.

/media/uploads/nixnax/pppd-screen.png

Caveats

PPP Blinky is an extremely sparse implementation (1.5k lines) of HTTP,WebSocket,TCP, UDP, ICMP, IPCP and LCP over PPP, requiring around 8kB of RAM. The minimum functionality required to establish connectivity is implemented. These are often acceptable tradeoffs for embedded projects as well as a handy tool to learn the practical details of everyday networking implementations.

PPP-Blinky/ppp-blinky.cpp@152:025c73b6c0a9, 2017-09-01 (annotated)

Committer:: nixnax
Date:: Fri Sep 01 15:25:04 2017 +0000
Revision:: 152:025c73b6c0a9
Parent:: 150:3366bf3d294e
Child:: 153:7993def8663f

PPP, IP and TCP header structures

Who changed what in which revision?

User	Revision	Line number	New contents of line
nixnax	142:54d1543e23e5	1	// PPP-Blinky - "The Most Basic Internet Of a Thing"
nixnax	142:54d1543e23e5	2	// A Tiny HTTP Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax	142:54d1543e23e5	3	// Receives UDP packets and responds to ping (ICMP Echo requests)
nixnax	142:54d1543e23e5	4	// WebSocket Service - see https://en.wikipedia.org/wiki/WebSocket
nixnax	142:54d1543e23e5	5
nixnax	142:54d1543e23e5	6	// Copyright 2016/2017 Nicolas Nackel aka Nixnax. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nixnax	142:54d1543e23e5	7
nixnax	142:54d1543e23e5	8	// Notes and Instructions
nixnax	142:54d1543e23e5	9	// http://bit.ly/PPP-Blinky-Instructions
nixnax	142:54d1543e23e5	10	// http://bit.ly/win-rasdial-config
nixnax	142:54d1543e23e5	11
nixnax	142:54d1543e23e5	12	// Handy reading material
nixnax	142:54d1543e23e5	13	// https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax	142:54d1543e23e5	14	// https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax	142:54d1543e23e5	15	// http://atari.kensclassics.org/wcomlog.htm
nixnax	142:54d1543e23e5	16
nixnax	142:54d1543e23e5	17	// Handy tools
nixnax	142:54d1543e23e5	18	// https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax	142:54d1543e23e5	19	// https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax	142:54d1543e23e5	20	// http://pingtester.net/ - nice tool for high rate ping testing
nixnax	142:54d1543e23e5	21	// http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax	142:54d1543e23e5	22	// https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax	142:54d1543e23e5	23	// https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax	142:54d1543e23e5	24	// Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax	142:54d1543e23e5	25
nixnax	142:54d1543e23e5	26	// Connecting PPP-Blinky to Linux
nixnax	142:54d1543e23e5	27	// PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax	142:54d1543e23e5	28	// pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax	142:54d1543e23e5	29	// in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax	142:54d1543e23e5	30	// See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax	142:54d1543e23e5	31
nixnax	142:54d1543e23e5	32	// Special pages when PPP-Blinky is running
nixnax	142:54d1543e23e5	33	// 172.10.10.2 root page
nixnax	143:c5019f856a56	34	// 172.10.10.2/x returns a number that increments every time you request a page - this is handy for testing
nixnax	146:a45f49a2b29c	35	// 172.10.10.2/xb also returns a number, but issues a fast refresh meta command. This allows you to use your browser to benchmark page load speed
nixnax	142:54d1543e23e5	36	// 172.10.10.2/ws a simple WebSocket demo
nixnax	142:54d1543e23e5	37	// http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle
nixnax	142:54d1543e23e5	38
nixnax	142:54d1543e23e5	39	// Ok, enough talking, time to check out some code!!
nixnax	142:54d1543e23e5	40
nixnax	142:54d1543e23e5	41	#include "ppp-blinky.h"
nixnax	142:54d1543e23e5	42
nixnax	142:54d1543e23e5	43	// The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax	146:a45f49a2b29c	44	// Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor the debug output.
nixnax	142:54d1543e23e5	45	// Using the second serial port will slow down packet response time
nixnax	142:54d1543e23e5	46	// Note - the LPC11U24 does NOT have a second serial port
nixnax	146:a45f49a2b29c	47
nixnax	152:025c73b6c0a9	48	#define SERIAL_PORT_MONITOR_YES /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax	142:54d1543e23e5	49
nixnax	142:54d1543e23e5	50	// here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax	142:54d1543e23e5	51	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	52	#if defined(TARGET_LPC1768)
nixnax	142:54d1543e23e5	53	Serial xx(p9, p10); // Second serial port on LPC1768 - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	54	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	142:54d1543e23e5	55	Serial xx(PC_10, PC_11); // Second serial port on NUCLEO boards - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	56	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	57	#error The LPC11U24 does not have a second serial port to use for debugging - change SERIAL_PORT_MONITOR_YES back to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	58	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	142:54d1543e23e5	59	Serial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	142:54d1543e23e5	60	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	61	// change the next line to YOUR target board's second serial port pin definition if it's not present - and if it works, please send it to me - thanks!!!
nixnax	142:54d1543e23e5	62	Serial xx(p9, p10); // change this to YOUR board second serial port pin definition - and please send it to me if it works!!!
nixnax	142:54d1543e23e5	63	#else
nixnax	142:54d1543e23e5	64	#error Add your target board's second serial port here if you want to use debugging - or simply change SERIAL_PORT_MONITOR_YES to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	65	#endif
nixnax	142:54d1543e23e5	66	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we print debug messages */
nixnax	142:54d1543e23e5	67	#define debugPutc(x...) xx.putc(x)
nixnax	142:54d1543e23e5	68	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	69	#else
nixnax	142:54d1543e23e5	70	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	71	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	72	#define debugPutc(x...) {}
nixnax	142:54d1543e23e5	73	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	74	#endif
nixnax	142:54d1543e23e5	75
nixnax	142:54d1543e23e5	76	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	142:54d1543e23e5	77	#define v0 1
nixnax	142:54d1543e23e5	78	#define v1 0
nixnax	142:54d1543e23e5	79	#define v2 0
nixnax	142:54d1543e23e5	80	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	142:54d1543e23e5	81	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	82
nixnax	142:54d1543e23e5	83	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	84	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	85
nixnax	142:54d1543e23e5	86	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	87	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	88	<html>\
nixnax	142:54d1543e23e5	89	<head>\
nixnax	146:a45f49a2b29c	90	<title>mbed PPP-Blinky</title>\r\n\
nixnax	146:a45f49a2b29c	91	<script>\r\n\
nixnax	142:54d1543e23e5	92	window.onload=function(){\
nixnax	142:54d1543e23e5	93	setInterval(function(){function x(){return document.getElementById('w');};\
nixnax	146:a45f49a2b29c	94	x().textContent=parseInt(x().textContent)+1;},100);};\r\n\
nixnax	146:a45f49a2b29c	95	</script>\r\n\
nixnax	142:54d1543e23e5	96	</head>\
nixnax	142:54d1543e23e5	97	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	98	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	99	<h1 id=\"w\">0</h1>\
nixnax	142:54d1543e23e5	100	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	142:54d1543e23e5	101	<h1><a href=\"/ws\">WebSocket Demo</a></h1>\
nixnax	142:54d1543e23e5	102	<h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	103	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	142:54d1543e23e5	104	<h1><a href=\"http://jsfiddle.net/d26cyuh2/\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	105	</body>\
nixnax	146:a45f49a2b29c	106	</html>\r\n"; // size = 644 bytes plus 1 null byte = 645 bytes
nixnax	142:54d1543e23e5	107
nixnax	150:3366bf3d294e	108	// this is websocket demo we serve when GET /ws is requested
nixnax	142:54d1543e23e5	109	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	110	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	111	<html>\
nixnax	142:54d1543e23e5	112	<head>\
nixnax	142:54d1543e23e5	113	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	114	<script>\
nixnax	142:54d1543e23e5	115	window.onload=function(){\
nixnax	142:54d1543e23e5	116	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	117	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	118	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	119	var ctr=0;\
nixnax	142:54d1543e23e5	120	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	121	btn.onclick=function(){\
nixnax	142:54d1543e23e5	122	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	123	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	124	x.onopen=function(){\
nixnax	142:54d1543e23e5	125	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	126	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	127	};\
nixnax	142:54d1543e23e5	128	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	129	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	130	} else {\
nixnax	142:54d1543e23e5	131	x.send(ctr);\
nixnax	142:54d1543e23e5	132	ctr=ctr+1;\
nixnax	142:54d1543e23e5	133	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	134	}\
nixnax	142:54d1543e23e5	135	};\
nixnax	142:54d1543e23e5	136	};\
nixnax	142:54d1543e23e5	137	</script>\
nixnax	142:54d1543e23e5	138	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	139	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	140	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	141	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	142	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	143	</body>\
nixnax	142:54d1543e23e5	144	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	145
nixnax	142:54d1543e23e5	146	// The serial port on your mbed hardware. Your PC should be configured to view this port as a standard dial-up networking modem.
nixnax	142:54d1543e23e5	147	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	148	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	149	// See instructions at the top.
nixnax	142:54d1543e23e5	150	// On a typical mbed hardware platform this serial port is a USB virtual com port (VCP) and the USB serial driver is supplied by the board vendor.
nixnax	142:54d1543e23e5	151	BufferedSerial pc(USBTX, USBRX, 100); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	152
nixnax	142:54d1543e23e5	153	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	154
nixnax	142:54d1543e23e5	155	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	156	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	157
nixnax	152:025c73b6c0a9	158
nixnax	142:54d1543e23e5	159	/// a structure to keep all our ppp globals in
nixnax	142:54d1543e23e5	160	struct pppType {
nixnax	142:54d1543e23e5	161	int online; // we hunt for a PPP connection if this is zero
nixnax	143:c5019f856a56	162	int hostIP; // ip address of host
nixnax	145:098b6ed2f7f2	163	int fcs; // PPP "frame check sequence" - a 16-bit HDLC-like checksum used in all PPP frames
nixnax	142:54d1543e23e5	164	int ledState; // state of LED1
nixnax	146:a45f49a2b29c	165	int responseCounter;
nixnax	142:54d1543e23e5	166	int firstFrame; // cleared after first frame
nixnax	142:54d1543e23e5	167	struct {
nixnax	142:54d1543e23e5	168	#define RXBUFLEN (1<<11)
nixnax	142:54d1543e23e5	169	// the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 2048 bytes)
nixnax	142:54d1543e23e5	170	char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax	142:54d1543e23e5	171	int head;
nixnax	142:54d1543e23e5	172	int tail;
nixnax	142:54d1543e23e5	173	int rtail;
nixnax	142:54d1543e23e5	174	int buflevel;
nixnax	142:54d1543e23e5	175	} rx; // serial port objects
nixnax	142:54d1543e23e5	176	struct {
nixnax	142:54d1543e23e5	177	int len; // number of bytes in buffer
nixnax	142:54d1543e23e5	178	int crc; // PPP CRC (frame check)
nixnax	152:025c73b6c0a9	179	#define PPP_max_size 1600
nixnax	152:025c73b6c0a9	180	// we are assuming 100 bytes more than MTU size of 1500
nixnax	152:025c73b6c0a9	181	union {
nixnax	152:025c73b6c0a9	182	char buf[PPP_max_size]; // send and receive buffer large enough for largest IP packet
nixnax	152:025c73b6c0a9	183	ipHeaderType ip;
nixnax	152:025c73b6c0a9	184	tcpHeaderType1 tcp1;
nixnax	152:025c73b6c0a9	185	tcpHeaderType2 tcp2;
nixnax	152:025c73b6c0a9	186	};
nixnax	142:54d1543e23e5	187	} pkt; // ppp buffer objects
nixnax	142:54d1543e23e5	188	struct {
nixnax	142:54d1543e23e5	189	int frameStartIndex; // frame start marker
nixnax	142:54d1543e23e5	190	int frameEndIndex; // frame end marker
nixnax	142:54d1543e23e5	191	} hdlc; // hdlc frame objects
nixnax	142:54d1543e23e5	192	struct {
nixnax	142:54d1543e23e5	193	unsigned int ident; // our IP ident value (outgoing frame count)
nixnax	142:54d1543e23e5	194	} ip; // ip related object
nixnax	142:54d1543e23e5	195	};
nixnax	142:54d1543e23e5	196
nixnax	142:54d1543e23e5	197	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	198
nixnax	142:54d1543e23e5	199	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	200	void pppInitStruct()
nixnax	142:54d1543e23e5	201	{
nixnax	142:54d1543e23e5	202	memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax	142:54d1543e23e5	203	ppp.online=0;
nixnax	142:54d1543e23e5	204	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	205	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	206	ppp.rx.head=0;
nixnax	142:54d1543e23e5	207	ppp.rx.buflevel=0;
nixnax	142:54d1543e23e5	208	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	209	ppp.ip.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	210	ppp.ledState=0;
nixnax	142:54d1543e23e5	211	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	212	ppp.responseCounter=0;
nixnax	142:54d1543e23e5	213	ppp.firstFrame=1;
nixnax	142:54d1543e23e5	214	}
nixnax	142:54d1543e23e5	215
nixnax	142:54d1543e23e5	216	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	217	void led1Toggle()
nixnax	142:54d1543e23e5	218	{
nixnax	142:54d1543e23e5	219	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	220	ppp.ledState++;
nixnax	142:54d1543e23e5	221	}
nixnax	142:54d1543e23e5	222
nixnax	152:025c73b6c0a9	223	/// returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax	150:3366bf3d294e	224	int connectedPpp()
nixnax	142:54d1543e23e5	225	{
nixnax	142:54d1543e23e5	226	return ppp.online;
nixnax	143:c5019f856a56	227	}
nixnax	142:54d1543e23e5	228
nixnax	143:c5019f856a56	229	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	230	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	142:54d1543e23e5	231	void checkPc()
nixnax	142:54d1543e23e5	232	{
nixnax	142:54d1543e23e5	233	char ch;
nixnax	142:54d1543e23e5	234	if ( pc.readable() ) {
nixnax	142:54d1543e23e5	235	int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax	142:54d1543e23e5	236	if ( hd == ppp.rx.rtail ) {
nixnax	142:54d1543e23e5	237	debugPrintf("\nReceive buffer full\n");
nixnax	142:54d1543e23e5	238	return;
nixnax	142:54d1543e23e5	239	}
nixnax	142:54d1543e23e5	240	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	241	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	142:54d1543e23e5	242	if ( ppp.online == 0 ) {
nixnax	142:54d1543e23e5	243	if (ch == 0x7E) {
nixnax	142:54d1543e23e5	244	ppp.online = 1;
nixnax	142:54d1543e23e5	245	}
nixnax	142:54d1543e23e5	246	}
nixnax	142:54d1543e23e5	247	ppp.rx.head = hd; // update head pointer
nixnax	142:54d1543e23e5	248	ppp.rx.buflevel++;
nixnax	142:54d1543e23e5	249	}
nixnax	142:54d1543e23e5	250	}
nixnax	142:54d1543e23e5	251
nixnax	142:54d1543e23e5	252	/// print to debug port while checking for incoming characters
nixnax	142:54d1543e23e5	253	void putcWhileCheckingInput( char outByte )
nixnax	142:54d1543e23e5	254	{
nixnax	142:54d1543e23e5	255	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	256	checkPc();
nixnax	142:54d1543e23e5	257	debugPutc( outByte );
nixnax	142:54d1543e23e5	258	checkPc();
nixnax	142:54d1543e23e5	259	#endif
nixnax	142:54d1543e23e5	260	}
nixnax	142:54d1543e23e5	261
nixnax	142:54d1543e23e5	262	/// puts to debug port while checking the PPP input stream
nixnax	142:54d1543e23e5	263	void putsWhileCheckingInput( char * data )
nixnax	142:54d1543e23e5	264	{
nixnax	142:54d1543e23e5	265	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	266	char * nextChar = data;
nixnax	142:54d1543e23e5	267	while( *nextChar != 0 ) {
nixnax	142:54d1543e23e5	268	putcWhileCheckingInput( *nextChar ); // write one character to debug port while checking input
nixnax	142:54d1543e23e5	269	nextChar++;
nixnax	142:54d1543e23e5	270	}
nixnax	142:54d1543e23e5	271	#endif
nixnax	142:54d1543e23e5	272	}
nixnax	142:54d1543e23e5	273
nixnax	145:098b6ed2f7f2	274	/// Initialize the PPP FCS (frame check sequence) total
nixnax	145:098b6ed2f7f2	275	void fcsReset()
nixnax	142:54d1543e23e5	276	{
nixnax	145:098b6ed2f7f2	277	ppp.fcs=0xffff; // crc restart
nixnax	142:54d1543e23e5	278	}
nixnax	142:54d1543e23e5	279
nixnax	145:098b6ed2f7f2	280	/// update the cumulative PPP FCS (frame check sequence)
nixnax	145:098b6ed2f7f2	281	void fcsDo(int x)
nixnax	142:54d1543e23e5	282	{
nixnax	142:54d1543e23e5	283	for (int i=0; i<8; i++) {
nixnax	145:098b6ed2f7f2	284	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1; // crc calculator
nixnax	142:54d1543e23e5	285	x>>=1;
nixnax	142:54d1543e23e5	286	}
nixnax	142:54d1543e23e5	287	checkPc(); // handle input
nixnax	142:54d1543e23e5	288	}
nixnax	142:54d1543e23e5	289
nixnax	145:098b6ed2f7f2	290	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	291	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	292	{
nixnax	145:098b6ed2f7f2	293	fcsReset();
nixnax	145:098b6ed2f7f2	294	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	295	return ppp.fcs;
nixnax	142:54d1543e23e5	296	}
nixnax	142:54d1543e23e5	297
nixnax	142:54d1543e23e5	298	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	299	int pc_getBuf()
nixnax	142:54d1543e23e5	300	{
nixnax	142:54d1543e23e5	301	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	142:54d1543e23e5	302	ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax	142:54d1543e23e5	303	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	304	return x;
nixnax	142:54d1543e23e5	305	}
nixnax	142:54d1543e23e5	306
nixnax	142:54d1543e23e5	307	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	308	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	309	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	142:54d1543e23e5	310	/// In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	311	void dumpPPPFrame()
nixnax	142:54d1543e23e5	312	{
nixnax	142:54d1543e23e5	313	char pbuf[30];
nixnax	142:54d1543e23e5	314	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	315	checkPc();
nixnax	142:54d1543e23e5	316	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	142:54d1543e23e5	317	checkPc();
nixnax	142:54d1543e23e5	318	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	319	}
nixnax	142:54d1543e23e5	320	checkPc();
nixnax	142:54d1543e23e5	321	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	142:54d1543e23e5	322	checkPc();
nixnax	142:54d1543e23e5	323	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	324	}
nixnax	142:54d1543e23e5	325
nixnax	142:54d1543e23e5	326	/// Process a received PPP frame
nixnax	142:54d1543e23e5	327	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	328	{
nixnax	142:54d1543e23e5	329	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	330	if(start==end) {
nixnax	142:54d1543e23e5	331	return; // empty frame
nixnax	142:54d1543e23e5	332	}
nixnax	145:098b6ed2f7f2	333	fcsReset();
nixnax	142:54d1543e23e5	334	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	335	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	336	int unstuff=0;
nixnax	142:54d1543e23e5	337	int idx = start;
nixnax	142:54d1543e23e5	338	while(1) {
nixnax	142:54d1543e23e5	339	checkPc();
nixnax	142:54d1543e23e5	340	if (unstuff==0) {
nixnax	142:54d1543e23e5	341	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	342	else {
nixnax	142:54d1543e23e5	343	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	344	ppp.pkt.len++;
nixnax	142:54d1543e23e5	345	dest++;
nixnax	145:098b6ed2f7f2	346	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	347	}
nixnax	142:54d1543e23e5	348	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	349	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	350	ppp.pkt.len++;
nixnax	142:54d1543e23e5	351	dest++;
nixnax	145:098b6ed2f7f2	352	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	353	unstuff=0;
nixnax	142:54d1543e23e5	354	}
nixnax	142:54d1543e23e5	355	idx = (idx+1) & (RXBUFLEN-1);
nixnax	142:54d1543e23e5	356	if (idx == end) break;
nixnax	142:54d1543e23e5	357	}
nixnax	145:098b6ed2f7f2	358	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	359	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	360	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	361	determinePacketType();
nixnax	142:54d1543e23e5	362	} else {
nixnax	142:54d1543e23e5	363	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	364	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	365	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	366	checkPc();
nixnax	142:54d1543e23e5	367	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	142:54d1543e23e5	368	checkPc();
nixnax	142:54d1543e23e5	369	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	370	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	371	#endif
nixnax	142:54d1543e23e5	372	}
nixnax	142:54d1543e23e5	373	}
nixnax	142:54d1543e23e5	374
nixnax	142:54d1543e23e5	375	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	376	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	377	{
nixnax	142:54d1543e23e5	378	checkPc(); // check input
nixnax	142:54d1543e23e5	379	pc.putc(ch);
nixnax	142:54d1543e23e5	380	checkPc();
nixnax	142:54d1543e23e5	381	}
nixnax	142:54d1543e23e5	382
nixnax	142:54d1543e23e5	383	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	384	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	385	{
nixnax	142:54d1543e23e5	386	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	387	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	388	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	389	} else {
nixnax	142:54d1543e23e5	390	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	391	}
nixnax	142:54d1543e23e5	392	}
nixnax	142:54d1543e23e5	393
nixnax	142:54d1543e23e5	394	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	395	void sendPppFrame()
nixnax	143:c5019f856a56	396	{
nixnax	145:098b6ed2f7f2	397	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	398	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	399	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	400	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	401	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	402	wait_us(86); // wait one character time
nixnax	142:54d1543e23e5	403	checkPc();
nixnax	142:54d1543e23e5	404	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	405	}
nixnax	142:54d1543e23e5	406	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	407	}
nixnax	142:54d1543e23e5	408
nixnax	143:c5019f856a56	409	/// convert a network ip address in the buffer to an integer (IP adresses are big-endian, i.e most significant byte first)
nixnax	143:c5019f856a56	410	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	411	{
nixnax	143:c5019f856a56	412	int result=0;
nixnax	143:c5019f856a56	413	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	414	return result;
nixnax	143:c5019f856a56	415	}
nixnax	143:c5019f856a56	416
nixnax	142:54d1543e23e5	417	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	418	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	419	{
nixnax	142:54d1543e23e5	420	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	143:c5019f856a56	421	if(ppp.pkt.buf[8]==3) {
nixnax	143:c5019f856a56	422	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	143:c5019f856a56	423	debugPrintf("Host IP = %d.%d.%d.%d (%08x)\n", ppp.pkt.buf[10],ppp.pkt.buf[11],ppp.pkt.buf[12],ppp.pkt.buf[13],ppp.hostIP);
nixnax	143:c5019f856a56	424	}
nixnax	143:c5019f856a56	425
nixnax	142:54d1543e23e5	426	ppp.pkt.buf[4]=2; // change code to ack
nixnax	144:01d98cf7738e	427	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	428
nixnax	142:54d1543e23e5	429	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	142:54d1543e23e5	430	ppp.pkt.buf[4]=1; // change code to request
nixnax	142:54d1543e23e5	431	ppp.pkt.buf[7]=4; // no options in this request
nixnax	142:54d1543e23e5	432	ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	433	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	434	}
nixnax	142:54d1543e23e5	435
nixnax	142:54d1543e23e5	436	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	437	void ipcpAckHandler()
nixnax	142:54d1543e23e5	438	{
nixnax	142:54d1543e23e5	439	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	440	}
nixnax	142:54d1543e23e5	441
nixnax	143:c5019f856a56	442	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	443	/// This is how Linux responds to an IPCP request with no options - Windows assumes any IP address on the submnet is OK.
nixnax	142:54d1543e23e5	444	void ipcpNackHandler()
nixnax	142:54d1543e23e5	445	{
nixnax	146:a45f49a2b29c	446	debugPrintf("Their IPCP Nack\n");
nixnax	142:54d1543e23e5	447	if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax	142:54d1543e23e5	448	ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	449	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	450	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	451	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	452	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	453	}
nixnax	142:54d1543e23e5	454	}
nixnax	142:54d1543e23e5	455
nixnax	142:54d1543e23e5	456	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	457	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	458	{
nixnax	142:54d1543e23e5	459	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	460	}
nixnax	142:54d1543e23e5	461
nixnax	142:54d1543e23e5	462	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	463	void IPCPframe()
nixnax	142:54d1543e23e5	464	{
nixnax	142:54d1543e23e5	465	int code = ppp.pkt.buf[4]; // packet type is here
nixnax	142:54d1543e23e5	466	switch (code) {
nixnax	142:54d1543e23e5	467	case 1:
nixnax	142:54d1543e23e5	468	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	469	break;
nixnax	142:54d1543e23e5	470	case 2:
nixnax	142:54d1543e23e5	471	ipcpAckHandler();
nixnax	142:54d1543e23e5	472	break;
nixnax	142:54d1543e23e5	473	case 3:
nixnax	142:54d1543e23e5	474	ipcpNackHandler();
nixnax	142:54d1543e23e5	475	break;
nixnax	142:54d1543e23e5	476	default:
nixnax	142:54d1543e23e5	477	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	478	}
nixnax	142:54d1543e23e5	479	}
nixnax	142:54d1543e23e5	480
nixnax	142:54d1543e23e5	481	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	142:54d1543e23e5	482	unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax	142:54d1543e23e5	483	{
nixnax	142:54d1543e23e5	484	unsigned int i,hi,lo,sum;
nixnax	142:54d1543e23e5	485	unsigned char placeHolder;
nixnax	142:54d1543e23e5	486	if (len&1) {
nixnax	142:54d1543e23e5	487	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	488	ptr[len]=0; // if the byte count is odd, insert one extra zero byte is after the last real byte because we sum byte PAIRS
nixnax	142:54d1543e23e5	489	}
nixnax	142:54d1543e23e5	490	sum=0;
nixnax	142:54d1543e23e5	491	i=0;
nixnax	142:54d1543e23e5	492	while ( i<len ) {
nixnax	142:54d1543e23e5	493	checkPc();
nixnax	142:54d1543e23e5	494	hi = ptr[i++];
nixnax	142:54d1543e23e5	495	lo = ptr[i++];
nixnax	142:54d1543e23e5	496	sum = sum + ( (hi<<8) \| lo );
nixnax	142:54d1543e23e5	497	}
nixnax	142:54d1543e23e5	498	if (len&1) {
nixnax	142:54d1543e23e5	499	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	500	}
nixnax	142:54d1543e23e5	501	sum = (sum & 0xffff) + (sum>>16);
nixnax	142:54d1543e23e5	502	sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax	142:54d1543e23e5	503	return ~sum;
nixnax	142:54d1543e23e5	504	}
nixnax	142:54d1543e23e5	505
nixnax	142:54d1543e23e5	506	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	507	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	508	{
nixnax	146:a45f49a2b29c	509	ppp.pkt.buf[4+10]=0; // zero the checsum in the IP header
nixnax	146:a45f49a2b29c	510	ppp.pkt.buf[4+11]=0; // zero the checksum in the IP header
nixnax	146:a45f49a2b29c	511	int len =(ppp.pkt.buf[4]&0xf)*4; // length of IP header in bytes
nixnax	146:a45f49a2b29c	512	char * ptr = ppp.pkt.buf+4; // start of IP packet
nixnax	142:54d1543e23e5	513	int sum=0;
nixnax	142:54d1543e23e5	514	for (int i=0; i<len/2; i++) {
nixnax	142:54d1543e23e5	515	int hi = *ptr;
nixnax	142:54d1543e23e5	516	ptr++;
nixnax	142:54d1543e23e5	517	int lo = *ptr;
nixnax	142:54d1543e23e5	518	ptr++;
nixnax	142:54d1543e23e5	519	int val = ( lo & 0xff ) \| ( (hi<<8) & 0xff00 );
nixnax	142:54d1543e23e5	520	sum = sum + val;
nixnax	142:54d1543e23e5	521	checkPc();
nixnax	142:54d1543e23e5	522	}
nixnax	142:54d1543e23e5	523	sum = sum + (sum>>16);
nixnax	142:54d1543e23e5	524	sum = ~sum;
nixnax	146:a45f49a2b29c	525	ppp.pkt.buf[4+10]= (sum>>8);
nixnax	146:a45f49a2b29c	526	ppp.pkt.buf[4+11]= (sum );
nixnax	146:a45f49a2b29c	527	}
nixnax	146:a45f49a2b29c	528
nixnax	147:0f40005cbc5f	529	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	530	void swapIpAddresses()
nixnax	147:0f40005cbc5f	531	{
nixnax	147:0f40005cbc5f	532	char tempHold[4];
nixnax	147:0f40005cbc5f	533	memcpy(tempHold, ppp.pkt.buf+16,4); // tempHold <- source IP
nixnax	147:0f40005cbc5f	534	memcpy(ppp.pkt.buf+16, ppp.pkt.buf+20,4); // source <- dest
nixnax	147:0f40005cbc5f	535	memcpy(ppp.pkt.buf+20, tempHold,4); // dest <- tempHold
nixnax	147:0f40005cbc5f	536	}
nixnax	147:0f40005cbc5f	537
nixnax	149:969d98f6fb88	538	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	539	void swapIpPorts()
nixnax	149:969d98f6fb88	540	{
nixnax	149:969d98f6fb88	541	int headerSizeIP = 4*(ppp.pkt.buf[4]&0xf); // calculate size of IP header
nixnax	149:969d98f6fb88	542	char * ipSrcPort = 4 + ppp.pkt.buf + headerSizeIP + 0; // ip source port location
nixnax	149:969d98f6fb88	543	char * ipDstPort = 4 + ppp.pkt.buf + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	544	char tempHold[2];
nixnax	149:969d98f6fb88	545	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	546	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	547	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	548	}
nixnax	149:969d98f6fb88	549
nixnax	146:a45f49a2b29c	550	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	551	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	552	void UDPpacket()
nixnax	146:a45f49a2b29c	553	{
nixnax	146:a45f49a2b29c	554	char * ipHeader = ppp.pkt.buf+4; // udp packet start
nixnax	146:a45f49a2b29c	555	char * ipSizeBuf = ipHeader+2; // size of IP packet
nixnax	146:a45f49a2b29c	556	int headerSizeIP = 4*(ipHeader[0]&0xf); // size of IP header
nixnax	146:a45f49a2b29c	557	char * udpHeader = ipHeader + headerSizeIP; // udp info start
nixnax	146:a45f49a2b29c	558	char * udpLen = udpHeader+4; // udp data length
nixnax	146:a45f49a2b29c	559	char * udpCheckSum = udpHeader+6; // udp checksum
nixnax	146:a45f49a2b29c	560	char * udpData = udpHeader+8; // start of UDP data
nixnax	146:a45f49a2b29c	561	int udpLength = ((udpLen[0]<<8) \| udpLen[1]); // size of udp packet
nixnax	146:a45f49a2b29c	562	int udpDataSize = udpLength - 8; // size of udp data
nixnax	147:0f40005cbc5f	563
nixnax	146:a45f49a2b29c	564	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	147:0f40005cbc5f	565	char * srcIP = ipHeader+12; // IP source
nixnax	147:0f40005cbc5f	566	char * dstIP = ipHeader+16; // IP destination
nixnax	149:969d98f6fb88	567	char * udpSrcPort = udpHeader+0; // source port
nixnax	149:969d98f6fb88	568	char * udpDstPort = udpHeader+2; // destination port
nixnax	146:a45f49a2b29c	569	int udpSrc = (udpSrcPort[0]<<8)\|udpSrcPort[1]; // integer of UDP source port
nixnax	146:a45f49a2b29c	570	int udpDst = (udpDstPort[0]<<8)\|udpDstPort[1]; // integer of UDP dest port
nixnax	146:a45f49a2b29c	571	if(v0) debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrc);
nixnax	146:a45f49a2b29c	572	if(v0) debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDst);
nixnax	146:a45f49a2b29c	573	if(v0) debugPrintf("Len %03d", udpLength);
nixnax	146:a45f49a2b29c	574	if (v1) {
nixnax	146:a45f49a2b29c	575	int printSize = udpLength-8;
nixnax	146:a45f49a2b29c	576	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	577	for (int i=0; i<printSize; i++) {
nixnax	146:a45f49a2b29c	578	char ch = udpData[i];
nixnax	146:a45f49a2b29c	579	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	580	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	581	} else {
nixnax	146:a45f49a2b29c	582	debugPrintf("_");
nixnax	146:a45f49a2b29c	583	}
nixnax	146:a45f49a2b29c	584	}
nixnax	146:a45f49a2b29c	585	}
nixnax	146:a45f49a2b29c	586	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	587	#endif
nixnax	146:a45f49a2b29c	588	int echoFound = !strncmp(udpData,"echo ",5); // true if UDP message starts with "echo "
nixnax	146:a45f49a2b29c	589	int testFound = !strncmp(udpData,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	590	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	147:0f40005cbc5f	591	swapIpAddresses(); // swap IP source and destination
nixnax	149:969d98f6fb88	592	swapIpPorts(); // swap IP source and destination ports
nixnax	146:a45f49a2b29c	593	if (echoFound) {
nixnax	146:a45f49a2b29c	594	memcpy(udpData,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	146:a45f49a2b29c	595	char endString[] = "} UDP Server: PPP-Blinky\n"; // an appendix
nixnax	146:a45f49a2b29c	596	memcpy(udpData+udpLength-8,endString,sizeof(endString)-1); // add endstring size to the UDP message
nixnax	146:a45f49a2b29c	597	udpDataSize = udpDataSize + sizeof(endString)-1; // update udp data size with the size of the appendix
nixnax	146:a45f49a2b29c	598	}
nixnax	146:a45f49a2b29c	599	if (testFound) {
nixnax	146:a45f49a2b29c	600	char udpResponse[50];
nixnax	146:a45f49a2b29c	601	int n = 0;
nixnax	146:a45f49a2b29c	602	n = n+sprintf(udpResponse+n,"Response count %d\n",ppp.responseCounter++);
nixnax	146:a45f49a2b29c	603	memcpy(udpData,udpResponse,n); // copy response to the UDP data area
nixnax	146:a45f49a2b29c	604	udpDataSize = n; // new udp data size
nixnax	146:a45f49a2b29c	605	}
nixnax	146:a45f49a2b29c	606	udpLength = udpDataSize+8; // update udp packet length
nixnax	146:a45f49a2b29c	607	int ipSize = headerSizeIP + udpLength; // update ip packet length
nixnax	146:a45f49a2b29c	608	ppp.pkt.len = ipSize+2+4; // update ppp packet length
nixnax	146:a45f49a2b29c	609	udpLen[0] = udpLength>>8;
nixnax	146:a45f49a2b29c	610	udpLen[1] = udpLength; // update UDP length
nixnax	146:a45f49a2b29c	611	ipSizeBuf[0] = ipSize>>8;
nixnax	146:a45f49a2b29c	612	ipSizeBuf[1] = ipSize; // update IP length
nixnax	146:a45f49a2b29c	613	IpHeaderCheckSum(); // update IP header checksum
nixnax	146:a45f49a2b29c	614	memset(udpCheckSum,0,2); // we don't yet recompute the checksum (it's optional), so have to zero it
nixnax	146:a45f49a2b29c	615	sendPppFrame(); // send the UDP message back
nixnax	146:a45f49a2b29c	616	}
nixnax	142:54d1543e23e5	617	}
nixnax	142:54d1543e23e5	618
nixnax	142:54d1543e23e5	619	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	620	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	621	{
nixnax	142:54d1543e23e5	622	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	623	char * pktLen = ipPkt+2;
nixnax	142:54d1543e23e5	624	int packetLength = (pktLen[0]<<8) \| pktLen[1]; // icmp packet length
nixnax	142:54d1543e23e5	625	int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax	142:54d1543e23e5	626	char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax	142:54d1543e23e5	627	char * icmpSum = icmpType+2; // icmp checksum
nixnax	142:54d1543e23e5	628	#define ICMP_TYPE_PING_REQUEST 8
nixnax	142:54d1543e23e5	629	if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax	142:54d1543e23e5	630	char * ipTTL = ipPkt+8; // time to live
nixnax	147:0f40005cbc5f	631	ipTTL[0]--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	632	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	633	char * srcAdr = ipPkt+12;
nixnax	142:54d1543e23e5	634	char * dstAdr = ipPkt+16;
nixnax	142:54d1543e23e5	635	int icmpIdent = (icmpType[4]<<8)\|icmpType[5];
nixnax	142:54d1543e23e5	636	int icmpSequence = (icmpType[6]<<8)\|icmpType[7];
nixnax	142:54d1543e23e5	637	if(1) {
nixnax	142:54d1543e23e5	638	char pbuf[50];
nixnax	142:54d1543e23e5	639	checkPc();
nixnax	142:54d1543e23e5	640	sprintf(pbuf, "ICMP PING %d.%d.%d.%d %d.%d.%d.%d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax	142:54d1543e23e5	641	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	642	checkPc();
nixnax	142:54d1543e23e5	643	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	142:54d1543e23e5	644	checkPc();
nixnax	142:54d1543e23e5	645	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	646	}
nixnax	142:54d1543e23e5	647	#endif
nixnax	147:0f40005cbc5f	648	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	649	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	650	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	142:54d1543e23e5	651	icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	142:54d1543e23e5	652	icmpSum[0]=0;
nixnax	142:54d1543e23e5	653	icmpSum[1]=0; // zero the checksum for recalculation
nixnax	142:54d1543e23e5	654	int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax	142:54d1543e23e5	655	unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax	142:54d1543e23e5	656	icmpSum[0]=(sum>>8)&0xff;
nixnax	142:54d1543e23e5	657	icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax	142:54d1543e23e5	658
nixnax	142:54d1543e23e5	659	int printSize = icmpLength-8; // exclude size of icmp header
nixnax	142:54d1543e23e5	660	char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax	142:54d1543e23e5	661	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	662	if (0) {
nixnax	142:54d1543e23e5	663	for (int i=0; i<printSize; i++) {
nixnax	142:54d1543e23e5	664	char ch = icmpData[i];
nixnax	142:54d1543e23e5	665	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	666	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	667	} else {
nixnax	142:54d1543e23e5	668	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	669	}
nixnax	142:54d1543e23e5	670	}
nixnax	142:54d1543e23e5	671	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	672	}
nixnax	144:01d98cf7738e	673	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	674	} else {
nixnax	142:54d1543e23e5	675	if (v0) {
nixnax	142:54d1543e23e5	676	debugPrintf("ICMP type=%d \n", icmpType[0]);
nixnax	142:54d1543e23e5	677	}
nixnax	142:54d1543e23e5	678	}
nixnax	142:54d1543e23e5	679	}
nixnax	142:54d1543e23e5	680
nixnax	142:54d1543e23e5	681	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	682	void IGMPpacket()
nixnax	142:54d1543e23e5	683	{
nixnax	142:54d1543e23e5	684	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	685	}
nixnax	142:54d1543e23e5	686
nixnax	142:54d1543e23e5	687	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	688	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	689	{
nixnax	142:54d1543e23e5	690	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	691	checkPc(); // we are expecting the first character of the next packet
nixnax	142:54d1543e23e5	692	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	693	char * ident = ipPkt+4; // 2 bytes
nixnax	142:54d1543e23e5	694	#ifdef UNUSED_IP_VARIABLES
nixnax	142:54d1543e23e5	695	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	142:54d1543e23e5	696	char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	697	char * version = ipPkt; // top 4 bits
nixnax	142:54d1543e23e5	698	char * ihl = ipPkt; // bottom 4 bits
nixnax	142:54d1543e23e5	699	char * dscp = ipPkt+1; // top 6 bits
nixnax	142:54d1543e23e5	700	char * ecn = ipPkt+1; // lower 2 bits
nixnax	142:54d1543e23e5	701	char * pktLen = ipPkt+2; // 2 bytes
nixnax	142:54d1543e23e5	702	char * flags = ipPkt+6; // 2 bits
nixnax	142:54d1543e23e5	703	char * ttl = ipPkt+8; // 1 byte
nixnax	142:54d1543e23e5	704	char * protocol = ipPkt+9; // 1 byte
nixnax	142:54d1543e23e5	705	char * headercheck= ipPkt+10; // 2 bytes
nixnax	142:54d1543e23e5	706	int versionIP = (version[0]>>4)&0xf;
nixnax	142:54d1543e23e5	707	int headerSizeIP = (ihl[0]&0xf)*4;
nixnax	142:54d1543e23e5	708	int dscpIP = (dscp[0]>>2)&0x3f;
nixnax	142:54d1543e23e5	709	int ecnIP = ecn[0]&3;
nixnax	142:54d1543e23e5	710	int packetLength = (pktLen[0]<<8)\|pktLen[1]; // ip total packet length
nixnax	142:54d1543e23e5	711	int flagsIP = flags[0]>>14&3;
nixnax	142:54d1543e23e5	712	int ttlIP = ttl[0];
nixnax	142:54d1543e23e5	713	int protocolIP = protocol[0];
nixnax	142:54d1543e23e5	714	unsigned int checksumIP = (headercheck[0]<<8)\|headercheck[1];
nixnax	142:54d1543e23e5	715	#endif
nixnax	142:54d1543e23e5	716	int IPv4Id = (ident[0]<<8)\|ident[1];
nixnax	152:025c73b6c0a9	717	char pbuf[80]; // local print buffer
nixnax	142:54d1543e23e5	718	int n=0;
nixnax	142:54d1543e23e5	719	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	720	n=n+sprintf(pbuf+n, "%05d ",IPv4Id); // IPv4Id is a good way to correlate our dumps with net monitor or wireshark traces
nixnax	142:54d1543e23e5	721	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	722	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	152:025c73b6c0a9	723	char * srcAdr = (char *)&ppp.pkt.ip.srcAdr; // 4 bytes
nixnax	152:025c73b6c0a9	724	char * dstAdr = (char *)&ppp.pkt.ip.dstAdr; // 4 bytes = total of 20 bytes
nixnax	152:025c73b6c0a9	725	//n=n+sprintf(pbuf+n, " %x %x ", ppp.pkt.ip.x, ppp.pkt.ip.y);
nixnax	142:54d1543e23e5	726	n=n+sprintf(pbuf+n, " %d.%d.%d.%d %d.%d.%d.%d ",srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3], dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]); // full ip addresses
nixnax	142:54d1543e23e5	727	#endif
nixnax	142:54d1543e23e5	728	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	729	#ifndef TCP_HEADER_DUMP_YES
nixnax	142:54d1543e23e5	730	putsWhileCheckingInput('\x1b[30m\n'); // there is no TCP header dump, so terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	731	#endif
nixnax	142:54d1543e23e5	732	#endif
nixnax	152:025c73b6c0a9	733
nixnax	152:025c73b6c0a9	734
nixnax	142:54d1543e23e5	735	}
nixnax	142:54d1543e23e5	736
nixnax	142:54d1543e23e5	737	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	738	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	739	{
nixnax	142:54d1543e23e5	740	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	741	int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax	142:54d1543e23e5	742	char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax	142:54d1543e23e5	743	char * seqtcp = tcpStart + 4; // 4 bytes
nixnax	142:54d1543e23e5	744	char * acktcp = tcpStart + 8; // 4 bytes
nixnax	142:54d1543e23e5	745	char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax	142:54d1543e23e5	746	unsigned int seq = (seqtcp[0]<<24)\|(seqtcp[1]<<16)\|(seqtcp[2]<<8)\|(seqtcp[3]);
nixnax	142:54d1543e23e5	747	unsigned int ack = (acktcp[0]<<24)\|(acktcp[1]<<16)\|(acktcp[2]<<8)\|(acktcp[3]);
nixnax	142:54d1543e23e5	748	if (seq && ack) {} // shut up the compiler about unused variables
nixnax	142:54d1543e23e5	749	int flags = ((flagbitstcp[0]&1)<<8)\|flagbitstcp[1];
nixnax	142:54d1543e23e5	750	char flagInfo[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	751	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	752	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	753	memset(flagInfo,'.', 8); // fill string with "........"
nixnax	142:54d1543e23e5	754	flagInfo[8]=0; // null terminate string
nixnax	142:54d1543e23e5	755	if (flags & (1<<0)) flagInfo[7]='F';
nixnax	142:54d1543e23e5	756	if (flags & (1<<1)) flagInfo[6]='S';
nixnax	142:54d1543e23e5	757	if (flags & (1<<2)) flagInfo[5]='R';
nixnax	142:54d1543e23e5	758	if (flags & (1<<3)) flagInfo[4]='P';
nixnax	142:54d1543e23e5	759	if (flags & (1<<4)) flagInfo[3]='A';
nixnax	142:54d1543e23e5	760	if (flags & (1<<5)) flagInfo[2]='U';
nixnax	142:54d1543e23e5	761	if (flags & (1<<6)) flagInfo[1]='E';
nixnax	142:54d1543e23e5	762	if (flags & (1<<7)) flagInfo[0]='C';
nixnax	142:54d1543e23e5	763	#else
nixnax	142:54d1543e23e5	764	if (flags & (1<<4)) flagInfo[0]='A'; // choose the most important flag to print
nixnax	142:54d1543e23e5	765	if (flags & (1<<1)) flagInfo[0]='S';
nixnax	142:54d1543e23e5	766	if (flags & (1<<0)) flagInfo[0]='F';
nixnax	142:54d1543e23e5	767	if (flags & (1<<3)) flagInfo[0]='P';
nixnax	142:54d1543e23e5	768	if (flags & (1<<2)) flagInfo[0]='R';
nixnax	142:54d1543e23e5	769	flagInfo[1]=0; // ' '
nixnax	142:54d1543e23e5	770	flagInfo[2]=0;
nixnax	142:54d1543e23e5	771	#endif
nixnax	142:54d1543e23e5	772	putsWhileCheckingInput( flagInfo );
nixnax	142:54d1543e23e5	773	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	774	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	775	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	142:54d1543e23e5	776	#endif
nixnax	142:54d1543e23e5	777	if( outGoing && ( flags == 0x11 ) ) { // ACK/FIN - if this is an outgoing ACK/FIN its the end of a tcp conversation
nixnax	142:54d1543e23e5	778	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end of an HTTP the conversation
nixnax	142:54d1543e23e5	779	}
nixnax	142:54d1543e23e5	780	#endif
nixnax	142:54d1543e23e5	781	}
nixnax	142:54d1543e23e5	782
nixnax	143:c5019f856a56	783	/// Encode a buffer in base-64
nixnax	142:54d1543e23e5	784	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	785	{
nixnax	142:54d1543e23e5	786	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	787	int i,j,a,b,c;
nixnax	142:54d1543e23e5	788	i=0;
nixnax	142:54d1543e23e5	789	j=0;
nixnax	142:54d1543e23e5	790	while(1) {
nixnax	142:54d1543e23e5	791	if (i<len) {
nixnax	142:54d1543e23e5	792	a = in[i++];
nixnax	142:54d1543e23e5	793	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	794	} else break;
nixnax	142:54d1543e23e5	795	if (i<len) {
nixnax	142:54d1543e23e5	796	b = in[i++];
nixnax	142:54d1543e23e5	797	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	798	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	799	} else out[j++] = '=';
nixnax	142:54d1543e23e5	800	if (i<len) {
nixnax	142:54d1543e23e5	801	c = in[i++];
nixnax	142:54d1543e23e5	802	j--;
nixnax	142:54d1543e23e5	803	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	804	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	805	} else out[j++] = '=';
nixnax	142:54d1543e23e5	806	}
nixnax	142:54d1543e23e5	807	out[j]=0;
nixnax	142:54d1543e23e5	808	}
nixnax	142:54d1543e23e5	809
nixnax	142:54d1543e23e5	810	/// handle a request for an http websocket
nixnax	142:54d1543e23e5	811	/// we end up here if we enter the following javascript in a web browser console: x = new WebSocket("ws://172.10.10.2");
nixnax	142:54d1543e23e5	812	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	813	{
nixnax	142:54d1543e23e5	814	int n=0; // byte counter
nixnax	142:54d1543e23e5	815	char * key = strstr(dataStart, "Sec-WebSocket-Key: "); // search for the key in the payload
nixnax	142:54d1543e23e5	816	if (key != NULL) {
nixnax	142:54d1543e23e5	817	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	142:54d1543e23e5	818	char challenge [70];
nixnax	142:54d1543e23e5	819	strncpy(challenge,key+19,70); // a local buffer
nixnax	142:54d1543e23e5	820	*strchr(challenge,'\r')=0; // insert null so we can use sprintf
nixnax	142:54d1543e23e5	821	strncat(challenge,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11",70); // append websocket gui code
nixnax	142:54d1543e23e5	822	char shaOutput [20]; // sha1 output
nixnax	142:54d1543e23e5	823	sha1( shaOutput, challenge, strlen(challenge));
nixnax	142:54d1543e23e5	824	char encOut[50];
nixnax	142:54d1543e23e5	825	enc64( shaOutput, encOut, 20);
nixnax	142:54d1543e23e5	826	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	827	char * version = challenge;
nixnax	142:54d1543e23e5	828	strncpy(version, versionstring,70); // copy version string
nixnax	142:54d1543e23e5	829	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	830	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	831	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	832	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	833	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	834	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	835	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	836	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	837	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	838	}
nixnax	142:54d1543e23e5	839	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	840	}
nixnax	142:54d1543e23e5	841
nixnax	142:54d1543e23e5	842	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	843	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	844	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	845	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	846	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	847
nixnax	142:54d1543e23e5	848	/// respond to an HTTP request
nixnax	142:54d1543e23e5	849	int httpResponse(char * dataStart)
nixnax	142:54d1543e23e5	850	{
nixnax	142:54d1543e23e5	851	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	852	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	142:54d1543e23e5	853	if (n>0) return n; // if it's a WebSocket we already have the response, so return
nixnax	142:54d1543e23e5	854
nixnax	142:54d1543e23e5	855	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	856	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	857	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	142:54d1543e23e5	858
nixnax	146:a45f49a2b29c	859	ppp.responseCounter++; // increment the number of frames we have made
nixnax	142:54d1543e23e5	860
nixnax	142:54d1543e23e5	861	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	862	httpGetx = strncmp(dataStart, "GET /x", 6); // found a GET to /x which we will treat special (anything starting with /x, e.g. /x, /xyz, /xABC?pqr=123
nixnax	142:54d1543e23e5	863	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	864	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	865	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	142:54d1543e23e5	866	if( (httpGetRoot==0) \|\| (httpGetx==0) ) {
nixnax	142:54d1543e23e5	867	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	868	} else {
nixnax	142:54d1543e23e5	869	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	870	}
nixnax	142:54d1543e23e5	871	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	872	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	873	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	874	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	142:54d1543e23e5	875	n=n+sprintf(n+dataStart,"Content-Type: text/html; charset=us-ascii\r\n\r\n"); // http header must end with empty line (\r\n)
nixnax	142:54d1543e23e5	876	nHeader=n; // size of HTTP header
nixnax	142:54d1543e23e5	877	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	878	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	879	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	880	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	142:54d1543e23e5	881	} else if ( (httpGet5 == 'w') && (httpGet6 == 's') ) { // "ws" is a special page for websocket demo
nixnax	142:54d1543e23e5	882	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	883	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	142:54d1543e23e5	884	} else {
nixnax	142:54d1543e23e5	885	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	886
nixnax	142:54d1543e23e5	887	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	888	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	889	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	890	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	891	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	892	#else
nixnax	142:54d1543e23e5	893	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	142:54d1543e23e5	894	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	895	}
nixnax	142:54d1543e23e5	896	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	897	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	898	#endif
nixnax	142:54d1543e23e5	899	} else {
nixnax	142:54d1543e23e5	900	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	901	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	902	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	903	}
nixnax	142:54d1543e23e5	904	}
nixnax	142:54d1543e23e5	905	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	906	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	907	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	908	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	909	return n; // total byte size of our response
nixnax	142:54d1543e23e5	910	}
nixnax	142:54d1543e23e5	911
nixnax	142:54d1543e23e5	912	/// handle TCP data that is not an HTTP get
nixnax	142:54d1543e23e5	913	/// this is the response if we have TCP data but it's not an HTTP GET
nixnax	142:54d1543e23e5	914	/// this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax	142:54d1543e23e5	915	/// this could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	916	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	917	{
nixnax	142:54d1543e23e5	918	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	919	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	142:54d1543e23e5	920	// this is most likely a websocket push message. you get this when you enter this in your browser console: x.send("my message");
nixnax	142:54d1543e23e5	921	if (0) putsWhileCheckingInput( "Got data from websocket send()\n" );
nixnax	142:54d1543e23e5	922
nixnax	142:54d1543e23e5	923	// for now we simply echo the websocket data back to the client - the client should therefore see an onmessage event
nixnax	142:54d1543e23e5	924	// to display the echoed data in your browser, enter the following into the browser console: x.onmessage = function(msg){ console.log( msg.data ); }
nixnax	142:54d1543e23e5	925	if (1) {
nixnax	142:54d1543e23e5	926	char mask [4];
nixnax	142:54d1543e23e5	927	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	142:54d1543e23e5	928	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	142:54d1543e23e5	929	if((dataStart[1]&0x80)==0x80) // test if the mask bit is set, which means all data is xor'ed with the mask
nixnax	142:54d1543e23e5	930	for (int i=0; i<websocketMessageSize; i++) dataStart[i+6]^= mask[i%4]; // unmask each byte with one of the mask bytes
nixnax	142:54d1543e23e5	931	dataStart[1] = len-2; // add four extra bytes to the message length because we don't use mask bytes for the send
nixnax	142:54d1543e23e5	932	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	142:54d1543e23e5	933	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	934	}
nixnax	142:54d1543e23e5	935	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	936	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	937	dataStart[1]=0; // we don't have mask bytes on
nixnax	142:54d1543e23e5	938	} else if (v1) putsWhileCheckingInput("TCP data received\n");
nixnax	142:54d1543e23e5	939	return n; // total byte size of our response
nixnax	142:54d1543e23e5	940	}
nixnax	142:54d1543e23e5	941
nixnax	142:54d1543e23e5	942	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	943	/// use the first few bytes to figure out if it's a websocket, an http request or just pure incoming TCP data
nixnax	142:54d1543e23e5	944	void tcpHandler()
nixnax	142:54d1543e23e5	945	{
nixnax	142:54d1543e23e5	946	// IP header
nixnax	142:54d1543e23e5	947	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	948	char * pktLen = ipPkt+2; // 2 bytes
nixnax	142:54d1543e23e5	949	char * protocol = ipPkt+9; // 1 byte
nixnax	142:54d1543e23e5	950	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	152:025c73b6c0a9	951	int headerSizeIP = 4 * ppp.pkt.ip.headerLength;
nixnax	152:025c73b6c0a9	952	int packetLength = __REV16(ppp.pkt.ip.length );//(pktLen[0]<<8)\|pktLen[1]; // ip total packet length
nixnax	152:025c73b6c0a9	953	int tcpSize = packetLength - headerSizeIP;
nixnax	142:54d1543e23e5	954
nixnax	142:54d1543e23e5	955	// TCP header
nixnax	152:025c73b6c0a9	956	char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax	142:54d1543e23e5	957	char * seqtcp = tcp + 4; // 4 bytes
nixnax	142:54d1543e23e5	958	char * acktcp = tcp + 8; // 4 bytes
nixnax	142:54d1543e23e5	959	char * offset = tcp + 12; // 4 bits
nixnax	142:54d1543e23e5	960	char * flagbitstcp = tcp + 12; // 9 bits
nixnax	142:54d1543e23e5	961	char * windowsizetcp = tcp + 14; // 2 bytes
nixnax	142:54d1543e23e5	962	char * checksumtcp = tcp + 16; // 2 bytes
nixnax	142:54d1543e23e5	963
nixnax	152:025c73b6c0a9	964	int shortIP = ppp.pkt.ip.headerLength==5 ? 1 : 0; // ip headers can be 20 or 24 bytes long
nixnax	152:025c73b6c0a9	965
nixnax	152:025c73b6c0a9	966	int headerSizeTCP = shortIP ? 4 * ppp.pkt.tcp1.offset : 4 * ppp.pkt.tcp2.offset;
nixnax	152:025c73b6c0a9	967
nixnax	142:54d1543e23e5	968	int protocolIP = protocol[0];
nixnax	142:54d1543e23e5	969	char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax	142:54d1543e23e5	970	int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax	142:54d1543e23e5	971	char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax	142:54d1543e23e5	972	unsigned int seq_in = (seqtcp[0]<<24)\|(seqtcp[1]<<16)\|(seqtcp[2]<<8)\|(seqtcp[3]);
nixnax	142:54d1543e23e5	973	unsigned int ack_in = (acktcp[0]<<24)\|(acktcp[1]<<16)\|(acktcp[2]<<8)\|(acktcp[3]);
nixnax	142:54d1543e23e5	974	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	975	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	976
nixnax	142:54d1543e23e5	977	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	142:54d1543e23e5	978	tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	142:54d1543e23e5	979	headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax	149:969d98f6fb88	980	ipPkt[0] = 0x45; // short IP packet size to 45
nixnax	142:54d1543e23e5	981	offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax	142:54d1543e23e5	982	packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	152:025c73b6c0a9	983
nixnax	152:025c73b6c0a9	984
nixnax	152:025c73b6c0a9	985	//pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	152:025c73b6c0a9	986	//pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	152:025c73b6c0a9	987	ppp.pkt.ip.length = __REV16(40);
nixnax	142:54d1543e23e5	988
nixnax	142:54d1543e23e5	989	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	990	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	142:54d1543e23e5	991	int flagsTCP = ((flagbitstcp[0]&1)<<8)\|flagbitstcp[1]; // the tcp flags we received
nixnax	142:54d1543e23e5	992	windowsizetcp[0] = (700 >> 8 ); // tcp window size hi byte
nixnax	142:54d1543e23e5	993	windowsizetcp[1] = (700 & 0xff); // tcp window size lo byte
nixnax	142:54d1543e23e5	994
nixnax	142:54d1543e23e5	995	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	996
nixnax	142:54d1543e23e5	997	switch ( flagsTCP ) {
nixnax	142:54d1543e23e5	998	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	999	return;
nixnax	142:54d1543e23e5	1000	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1001	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1002	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1003	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1004	break;
nixnax	142:54d1543e23e5	1005	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	142:54d1543e23e5	1006	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	142:54d1543e23e5	1007	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1008	dataLen = httpResponse(tcpDataOut); // send an http response
nixnax	142:54d1543e23e5	1009	} else {
nixnax	142:54d1543e23e5	1010	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not a web request, send a packet reporting number of received bytes
nixnax	142:54d1543e23e5	1011	}
nixnax	142:54d1543e23e5	1012	break;
nixnax	142:54d1543e23e5	1013	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1014	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1015	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1016	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1017	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1018	break;
nixnax	142:54d1543e23e5	1019	default:
nixnax	142:54d1543e23e5	1020	return; // ignore remaining packets
nixnax	142:54d1543e23e5	1021	} // switch
nixnax	142:54d1543e23e5	1022
nixnax	142:54d1543e23e5	1023	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1024	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1025	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1026	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1027
nixnax	142:54d1543e23e5	1028	acktcp[0]=ack_out>>24;
nixnax	142:54d1543e23e5	1029	acktcp[1]=ack_out>>16;
nixnax	142:54d1543e23e5	1030	acktcp[2]=ack_out>>8;
nixnax	142:54d1543e23e5	1031	acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax	142:54d1543e23e5	1032	seqtcp[0]=seq_out>>24;
nixnax	142:54d1543e23e5	1033	seqtcp[1]=seq_out>>16;
nixnax	142:54d1543e23e5	1034	seqtcp[2]=seq_out>>8;
nixnax	142:54d1543e23e5	1035	seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax	142:54d1543e23e5	1036
nixnax	142:54d1543e23e5	1037	flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1038
nixnax	142:54d1543e23e5	1039	// increment our outgoing ip packet counter
nixnax	142:54d1543e23e5	1040	ppp.ip.ident++; // get next ident number for our packet
nixnax	142:54d1543e23e5	1041
nixnax	142:54d1543e23e5	1042	// Now we recalculate all the header sizes
nixnax	142:54d1543e23e5	1043	tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax	142:54d1543e23e5	1044	int newPacketSize = headerSizeIP + tcpSize; // calculate size of the outgoing packet
nixnax	142:54d1543e23e5	1045	pktLen[0] = (newPacketSize>>8);
nixnax	142:54d1543e23e5	1046	pktLen[1]=newPacketSize; // ip total packet size
nixnax	142:54d1543e23e5	1047	ppp.pkt.len = newPacketSize+4+2; // ip packet length + 4-byte ppp prefix (ff 03 00 21) + 2 fcs (crc) bytes bytes at the end of the packet
nixnax	142:54d1543e23e5	1048
nixnax	142:54d1543e23e5	1049	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1050	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	142:54d1543e23e5	1051
nixnax	142:54d1543e23e5	1052	// now we have to build the so-called 12-byte TCP "pseudo-header" in front of the TCP header (containing some IP header values) in order to correctly calculate the TCP checksum
nixnax	142:54d1543e23e5	1053	// this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax	149:969d98f6fb88	1054	char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax	142:54d1543e23e5	1055	char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax	142:54d1543e23e5	1056	memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax	142:54d1543e23e5	1057	memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax	142:54d1543e23e5	1058	memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax	142:54d1543e23e5	1059	memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax	142:54d1543e23e5	1060	memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax	142:54d1543e23e5	1061	memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax	142:54d1543e23e5	1062	// pseudo-header built, now we can calculate TCP checksum
nixnax	142:54d1543e23e5	1063	checksumtcp[0]=0;
nixnax	142:54d1543e23e5	1064	checksumtcp[1]=0;
nixnax	142:54d1543e23e5	1065	unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax	142:54d1543e23e5	1066	checksumtcp[0]=pseudoHeaderSum>>8;
nixnax	142:54d1543e23e5	1067	checksumtcp[1]=pseudoHeaderSum;
nixnax	142:54d1543e23e5	1068	memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax	147:0f40005cbc5f	1069	// IP and TCP checksums done
nixnax	142:54d1543e23e5	1070	dumpHeaderIP(1); // dump outgoing IP header
nixnax	142:54d1543e23e5	1071	dumpHeaderTCP(1); // dump outgoing TCP header
nixnax	142:54d1543e23e5	1072	for (int i=0; i<45*1000/10; i++) { // 45 ms delay before sending frame - a typical internet delay time
nixnax	142:54d1543e23e5	1073	checkPc(); // catch any incoming characters
nixnax	142:54d1543e23e5	1074	wait_us(10); // wait less than 1 character duration at 115200
nixnax	142:54d1543e23e5	1075	}
nixnax	144:01d98cf7738e	1076	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1077	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1078	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1079	}
nixnax	142:54d1543e23e5	1080
nixnax	142:54d1543e23e5	1081
nixnax	142:54d1543e23e5	1082	/// dump the TCP data to the debug serial port
nixnax	142:54d1543e23e5	1083	void dumpDataTCP()
nixnax	142:54d1543e23e5	1084	{
nixnax	142:54d1543e23e5	1085	int ipPktLen = (ppp.pkt.buf[6]<<8)\|ppp.pkt.buf[7]; // overall length of ip packet
nixnax	142:54d1543e23e5	1086	int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax	142:54d1543e23e5	1087	int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax	142:54d1543e23e5	1088	int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax	142:54d1543e23e5	1089	if (v1) {
nixnax	142:54d1543e23e5	1090	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	1091	checkPc();
nixnax	142:54d1543e23e5	1092	sprintf(pbuf, "TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax	142:54d1543e23e5	1093	checkPc();
nixnax	142:54d1543e23e5	1094	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	1095	}
nixnax	142:54d1543e23e5	1096	if (dataLen > 0) {
nixnax	142:54d1543e23e5	1097	ppp.pkt.buf[4+ipHeaderLen+headerSizeTCP+dataLen]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	142:54d1543e23e5	1098	putsWhileCheckingInput( ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP ); // print the tcp payload data
nixnax	142:54d1543e23e5	1099	putsWhileCheckingInput("\n");
nixnax	142:54d1543e23e5	1100	}
nixnax	142:54d1543e23e5	1101	}
nixnax	142:54d1543e23e5	1102
nixnax	142:54d1543e23e5	1103	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1104	void TCPpacket()
nixnax	142:54d1543e23e5	1105	{
nixnax	142:54d1543e23e5	1106	dumpHeaderIP(0); // dump incoming packet header
nixnax	142:54d1543e23e5	1107	dumpHeaderTCP(0); // dump incoming packet header
nixnax	142:54d1543e23e5	1108	if (v2) dumpDataTCP();
nixnax	142:54d1543e23e5	1109	tcpHandler();
nixnax	142:54d1543e23e5	1110	}
nixnax	142:54d1543e23e5	1111
nixnax	142:54d1543e23e5	1112	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1113	void otherProtocol()
nixnax	142:54d1543e23e5	1114	{
nixnax	142:54d1543e23e5	1115	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1116	}
nixnax	142:54d1543e23e5	1117
nixnax	142:54d1543e23e5	1118	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1119	void IPframe()
nixnax	142:54d1543e23e5	1120	{
nixnax	142:54d1543e23e5	1121	int protocol = ppp.pkt.buf[13];
nixnax	142:54d1543e23e5	1122	switch (protocol) {
nixnax	142:54d1543e23e5	1123	case 1:
nixnax	142:54d1543e23e5	1124	ICMPpacket();
nixnax	142:54d1543e23e5	1125	break;
nixnax	142:54d1543e23e5	1126	case 2:
nixnax	142:54d1543e23e5	1127	IGMPpacket();
nixnax	142:54d1543e23e5	1128	break;
nixnax	142:54d1543e23e5	1129	case 17:
nixnax	142:54d1543e23e5	1130	UDPpacket();
nixnax	142:54d1543e23e5	1131	break;
nixnax	142:54d1543e23e5	1132	case 6:
nixnax	142:54d1543e23e5	1133	TCPpacket();
nixnax	142:54d1543e23e5	1134	break;
nixnax	142:54d1543e23e5	1135	default:
nixnax	142:54d1543e23e5	1136	otherProtocol();
nixnax	142:54d1543e23e5	1137	}
nixnax	142:54d1543e23e5	1138	}
nixnax	142:54d1543e23e5	1139
nixnax	142:54d1543e23e5	1140	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1141	void LCPconfReq()
nixnax	142:54d1543e23e5	1142	{
nixnax	142:54d1543e23e5	1143	debugPrintf("LCP Config ");
nixnax	142:54d1543e23e5	1144	if (ppp.pkt.buf[7] != 4) {
nixnax	142:54d1543e23e5	1145	ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1146	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1147	sendPppFrame();
nixnax	142:54d1543e23e5	1148	} else {
nixnax	142:54d1543e23e5	1149	ppp.pkt.buf[4]=2; // ack zero conf
nixnax	142:54d1543e23e5	1150	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1151	sendPppFrame();
nixnax	142:54d1543e23e5	1152	debugPrintf("LCP Ask\n");
nixnax	142:54d1543e23e5	1153	ppp.pkt.buf[4]=1; // request no options
nixnax	144:01d98cf7738e	1154	sendPppFrame();
nixnax	142:54d1543e23e5	1155	}
nixnax	142:54d1543e23e5	1156	}
nixnax	142:54d1543e23e5	1157
nixnax	142:54d1543e23e5	1158	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1159	void LCPconfAck()
nixnax	142:54d1543e23e5	1160	{
nixnax	142:54d1543e23e5	1161	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1162	}
nixnax	142:54d1543e23e5	1163
nixnax	143:c5019f856a56	1164	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1165	void LCPend()
nixnax	142:54d1543e23e5	1166	{
nixnax	142:54d1543e23e5	1167	ppp.pkt.buf[4]=6;
nixnax	144:01d98cf7738e	1168	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1169	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1170	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1171	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1172	}
nixnax	142:54d1543e23e5	1173
nixnax	142:54d1543e23e5	1174	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1175	void LCPother()
nixnax	142:54d1543e23e5	1176	{
nixnax	142:54d1543e23e5	1177	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1178	dumpPPPFrame();
nixnax	142:54d1543e23e5	1179	}
nixnax	142:54d1543e23e5	1180
nixnax	142:54d1543e23e5	1181	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1182	void LCPframe()
nixnax	142:54d1543e23e5	1183	{
nixnax	142:54d1543e23e5	1184	int code = ppp.pkt.buf[4];
nixnax	142:54d1543e23e5	1185	switch (code) {
nixnax	142:54d1543e23e5	1186	case 1:
nixnax	142:54d1543e23e5	1187	LCPconfReq();
nixnax	142:54d1543e23e5	1188	break; // config request
nixnax	142:54d1543e23e5	1189	case 2:
nixnax	142:54d1543e23e5	1190	LCPconfAck();
nixnax	142:54d1543e23e5	1191	break; // config ack
nixnax	142:54d1543e23e5	1192	case 5:
nixnax	142:54d1543e23e5	1193	LCPend();
nixnax	142:54d1543e23e5	1194	break; // end connection
nixnax	142:54d1543e23e5	1195	default:
nixnax	142:54d1543e23e5	1196	LCPother();
nixnax	142:54d1543e23e5	1197	}
nixnax	142:54d1543e23e5	1198	}
nixnax	142:54d1543e23e5	1199
nixnax	142:54d1543e23e5	1200	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1201	void discardedFrame()
nixnax	142:54d1543e23e5	1202	{
nixnax	142:54d1543e23e5	1203	if (v0) debugPrintf("Frame is not IP, IPCP or LCP: %02x %02x %02x %02x\n", ppp.pkt.buf[0],ppp.pkt.buf[1],ppp.pkt.buf[2],ppp.pkt.buf[3]);
nixnax	142:54d1543e23e5	1204	}
nixnax	142:54d1543e23e5	1205
nixnax	142:54d1543e23e5	1206	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1207	void determinePacketType()
nixnax	142:54d1543e23e5	1208	{
nixnax	142:54d1543e23e5	1209	if ( ppp.pkt.buf[0] != 0xff ) {
nixnax	142:54d1543e23e5	1210	debugPrintf("byte0 != ff\n");
nixnax	142:54d1543e23e5	1211	return;
nixnax	142:54d1543e23e5	1212	}
nixnax	142:54d1543e23e5	1213	if ( ppp.pkt.buf[1] != 3 ) {
nixnax	142:54d1543e23e5	1214	debugPrintf("byte1 != 3\n");
nixnax	142:54d1543e23e5	1215	return;
nixnax	142:54d1543e23e5	1216	}
nixnax	142:54d1543e23e5	1217	if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax	142:54d1543e23e5	1218	debugPrintf("byte2 != 21\n");
nixnax	142:54d1543e23e5	1219	return;
nixnax	142:54d1543e23e5	1220	}
nixnax	142:54d1543e23e5	1221	int packetType = ppp.pkt.buf[2];
nixnax	142:54d1543e23e5	1222	switch (packetType) {
nixnax	142:54d1543e23e5	1223	case 0xc0:
nixnax	142:54d1543e23e5	1224	LCPframe();
nixnax	142:54d1543e23e5	1225	break; // link control
nixnax	142:54d1543e23e5	1226	case 0x80:
nixnax	142:54d1543e23e5	1227	IPCPframe();
nixnax	142:54d1543e23e5	1228	break; // IP control
nixnax	142:54d1543e23e5	1229	case 0x00:
nixnax	142:54d1543e23e5	1230	IPframe();
nixnax	142:54d1543e23e5	1231	break; // IP itself
nixnax	142:54d1543e23e5	1232	default:
nixnax	142:54d1543e23e5	1233	discardedFrame();
nixnax	142:54d1543e23e5	1234	}
nixnax	142:54d1543e23e5	1235	}
nixnax	142:54d1543e23e5	1236
nixnax	146:a45f49a2b29c	1237	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1238	void sniff()
nixnax	146:a45f49a2b29c	1239	{
nixnax	146:a45f49a2b29c	1240	if ( pc.readable() ) putsWhileCheckingInput( "Sniff - Char available!\n" ); // if this prints anything it means there is a character in the serial receive buffer
nixnax	146:a45f49a2b29c	1241	}
nixnax	146:a45f49a2b29c	1242
nixnax	142:54d1543e23e5	1243	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1244	void waitForPppFrame()
nixnax	142:54d1543e23e5	1245	{
nixnax	142:54d1543e23e5	1246	while(1) {
nixnax	142:54d1543e23e5	1247	checkPc(); // handle received characters
nixnax	142:54d1543e23e5	1248	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1249	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1250	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1251	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1252	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1253	ppp.firstFrame=0;
nixnax	142:54d1543e23e5	1254	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1255	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	142:54d1543e23e5	1256	} else {
nixnax	142:54d1543e23e5	1257	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1258	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1259	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1260	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1261	break;
nixnax	142:54d1543e23e5	1262	}
nixnax	142:54d1543e23e5	1263	}
nixnax	142:54d1543e23e5	1264	}
nixnax	142:54d1543e23e5	1265	}
nixnax	142:54d1543e23e5	1266	}
nixnax	142:54d1543e23e5	1267
nixnax	142:54d1543e23e5	1268	/// scan for a connect string ("CLIENT") from the host PC, if found, we set ppp.oline to true, which will the IP packet scanner
nixnax	142:54d1543e23e5	1269	void scanForConnectString()
nixnax	142:54d1543e23e5	1270	{
nixnax	142:54d1543e23e5	1271	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1272	checkPc(); // gather received characters
nixnax	142:54d1543e23e5	1273	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1274	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1275	if (found1 != NULL) {
nixnax	142:54d1543e23e5	1276	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	143:c5019f856a56	1277	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	142:54d1543e23e5	1278	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1279	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1280	checkPc();
nixnax	142:54d1543e23e5	1281	}
nixnax	142:54d1543e23e5	1282	}
nixnax	142:54d1543e23e5	1283	}
nixnax	142:54d1543e23e5	1284
nixnax	144:01d98cf7738e	1285	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1286	void initializePpp()
nixnax	142:54d1543e23e5	1287	{
nixnax	142:54d1543e23e5	1288	pc.baud(115200); // USB serial port to pc
nixnax	144:01d98cf7738e	1289	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	142:54d1543e23e5	1290	debugPrintf("\x1b[2J\x1b[H\x1b[30mmbed PPP-Blinky HTTP & WebSocket server ready :)\n"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax	142:54d1543e23e5	1291	pppInitStruct(); // initialize all the PPP properties
nixnax	143:c5019f856a56	1292	}

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Repository details

Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	27 Dec 2016
Imports:	426
Forks:	1
Commits:	276
Dependents:	0
Dependencies:	1
Followers:	22

The code in this repository is MIT licensed.