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@206:7537ce2620c1, 2018-05-28 (annotated)

Committer:: nixnax
Date:: Mon May 28 05:56:41 2018 +0000
Revision:: 206:7537ce2620c1
Parent:: 205:c730866cb598
Child:: 207:28cd834b785d

Test comment

Who changed what in which revision?

User	Revision	Line number	New contents of line
nixnax	182:f039ec218c9f	1	// PPP-Blinky - "The Most Basic Internet 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	201:9fcf92e9f427	12	// Important - ensure that you are using the latest mbed firmware for your specific mbed target board
nixnax	201:9fcf92e9f427	13
nixnax	142:54d1543e23e5	14	// Handy reading material
nixnax	142:54d1543e23e5	15	// https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax	142:54d1543e23e5	16	// https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax	142:54d1543e23e5	17	// http://atari.kensclassics.org/wcomlog.htm
nixnax	142:54d1543e23e5	18
nixnax	142:54d1543e23e5	19	// Handy tools
nixnax	142:54d1543e23e5	20	// 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	21	// https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax	142:54d1543e23e5	22	// http://pingtester.net/ - nice tool for high rate ping testing
nixnax	142:54d1543e23e5	23	// 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	24	// https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax	142:54d1543e23e5	25	// https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax	142:54d1543e23e5	26	// 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	27
nixnax	142:54d1543e23e5	28	// Connecting PPP-Blinky to Linux
nixnax	142:54d1543e23e5	29	// PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax	142:54d1543e23e5	30	// pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax	142:54d1543e23e5	31	// 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	32	// See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax	142:54d1543e23e5	33
nixnax	142:54d1543e23e5	34	// Special pages when PPP-Blinky is running
nixnax	142:54d1543e23e5	35	// 172.10.10.2 root page
nixnax	182:f039ec218c9f	36	// 172.10.10.2/x returns the number of ppp frames sent - this is handy for testing
nixnax	182:f039ec218c9f	37	// 172.10.10.2/xb also returns number of ppp frames sent, but issues a fast refresh meta command. This allows you to use your browser to benchmark page load speed
nixnax	142:54d1543e23e5	38	// 172.10.10.2/ws a simple WebSocket demo
nixnax	182:f039ec218c9f	39	// http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle, showing cross-domain access
nixnax	206:7537ce2620c1	40	// test comment
nixnax	142:54d1543e23e5	41	// Ok, enough talking, time to check out some code!!
nixnax	142:54d1543e23e5	42
nixnax	142:54d1543e23e5	43	#include "ppp-blinky.h"
nixnax	142:54d1543e23e5	44
nixnax	142:54d1543e23e5	45	// The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax	146:a45f49a2b29c	46	// 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	47	// Using the second serial port will slow down packet response time
nixnax	142:54d1543e23e5	48	// Note - the LPC11U24 does NOT have a second serial port
nixnax	146:a45f49a2b29c	49
nixnax	183:6d3ba874b267	50	#define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax	142:54d1543e23e5	51
nixnax	142:54d1543e23e5	52	// here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax	142:54d1543e23e5	53	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	54	#if defined(TARGET_LPC1768)
nixnax	179:ba2b2ddd0da5	55	RawSerial 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	56	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	179:ba2b2ddd0da5	57	RawSerial 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	196:8791e241be80	58	#elif defined(TARGET_NUCLEO_L432KC)
nixnax	196:8791e241be80	59	RawSerial xx(PA_9, PA_10); // Second serial port on NUCLEO-L432KC - 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	60	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	61	#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	62	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	179:ba2b2ddd0da5	63	RawSerial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	193:48072570f41d	64	#elif defined(TARGET_KW41Z)
nixnax	194:5b23ebfb3626	65	RawSerial xx(PTC3, PTC2); // Second serial port on FRDM-KW41Z board
nixnax	142:54d1543e23e5	66	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	67	// 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	179:ba2b2ddd0da5	68	RawSerial 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	69	#else
nixnax	142:54d1543e23e5	70	#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	71	#endif
nixnax	179:ba2b2ddd0da5	72	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we can print debug messages */
nixnax	142:54d1543e23e5	73	#define debugPutc(x...) xx.putc(x)
nixnax	142:54d1543e23e5	74	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	75	#else
nixnax	142:54d1543e23e5	76	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	77	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	78	#define debugPutc(x...) {}
nixnax	142:54d1543e23e5	79	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	80	#endif
nixnax	142:54d1543e23e5	81
nixnax	142:54d1543e23e5	82	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	182:f039ec218c9f	83	#define v0 1
nixnax	142:54d1543e23e5	84	#define v1 0
nixnax	142:54d1543e23e5	85	#define v2 0
nixnax	182:f039ec218c9f	86	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	182:f039ec218c9f	87	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	88
nixnax	142:54d1543e23e5	89	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	90	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	91
nixnax	142:54d1543e23e5	92	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	93	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	94	<html>\
nixnax	142:54d1543e23e5	95	<head>\
nixnax	146:a45f49a2b29c	96	<title>mbed PPP-Blinky</title>\r\n\
nixnax	146:a45f49a2b29c	97	<script>\r\n\
nixnax	142:54d1543e23e5	98	window.onload=function(){\
nixnax	142:54d1543e23e5	99	setInterval(function(){function x(){return document.getElementById('w');};\
nixnax	146:a45f49a2b29c	100	x().textContent=parseInt(x().textContent)+1;},100);};\r\n\
nixnax	146:a45f49a2b29c	101	</script>\r\n\
nixnax	142:54d1543e23e5	102	</head>\
nixnax	142:54d1543e23e5	103	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	104	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	105	<h1 id=\"w\">0</h1>\
nixnax	142:54d1543e23e5	106	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	142:54d1543e23e5	107	<h1><a href=\"/ws\">WebSocket Demo</a></h1>\
nixnax	142:54d1543e23e5	108	<h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	109	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	142:54d1543e23e5	110	<h1><a href=\"http://jsfiddle.net/d26cyuh2/\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	111	</body>\
nixnax	146:a45f49a2b29c	112	</html>\r\n"; // size = 644 bytes plus 1 null byte = 645 bytes
nixnax	142:54d1543e23e5	113
nixnax	167:ff8a2d8beeb1	114	// this is a websocket demo html page we serve when GET /ws is requested
nixnax	142:54d1543e23e5	115	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	116	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	117	<html>\
nixnax	142:54d1543e23e5	118	<head>\
nixnax	142:54d1543e23e5	119	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	120	<script>\
nixnax	142:54d1543e23e5	121	window.onload=function(){\
nixnax	142:54d1543e23e5	122	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	123	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	124	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	125	var ctr=0;\
nixnax	142:54d1543e23e5	126	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	127	btn.onclick=function(){\
nixnax	142:54d1543e23e5	128	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	129	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	130	x.onopen=function(){\
nixnax	142:54d1543e23e5	131	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	132	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	133	};\
nixnax	142:54d1543e23e5	134	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	135	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	136	} else {\
nixnax	142:54d1543e23e5	137	x.send(ctr);\
nixnax	142:54d1543e23e5	138	ctr=ctr+1;\
nixnax	142:54d1543e23e5	139	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	140	}\
nixnax	142:54d1543e23e5	141	};\
nixnax	142:54d1543e23e5	142	};\
nixnax	142:54d1543e23e5	143	</script>\
nixnax	142:54d1543e23e5	144	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	145	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	146	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	147	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	148	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	149	</body>\
nixnax	142:54d1543e23e5	150	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	151
nixnax	142:54d1543e23e5	152	// 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	153	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	154	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	155	// See instructions at the top.
nixnax	142:54d1543e23e5	156	// 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	179:ba2b2ddd0da5	157	RawSerial pc (USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	158
nixnax	142:54d1543e23e5	159	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	160
nixnax	142:54d1543e23e5	161	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	162	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	163
nixnax	142:54d1543e23e5	164	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	165
nixnax	142:54d1543e23e5	166	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	167	void pppInitStruct()
nixnax	142:54d1543e23e5	168	{
nixnax	205:c730866cb598	169	memset( ppp.rx.buf, 0, RXBUFLEN+1); // one extra byte at the end which always remains zero so strstr() cannot exceed the buffer
nixnax	142:54d1543e23e5	170	ppp.online=0;
nixnax	142:54d1543e23e5	171	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	172	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	173	ppp.rx.head=0;
nixnax	142:54d1543e23e5	174	ppp.rx.buflevel=0;
nixnax	205:c730866cb598	175	ppp.rx.maxbuflevel=0;
nixnax	142:54d1543e23e5	176	ppp.pkt.len=0;
nixnax	154:18b2bd92f557	177	ppp.ipData.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	178	ppp.ledState=0;
nixnax	142:54d1543e23e5	179	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	180	ppp.responseCounter=0;
nixnax	142:54d1543e23e5	181	ppp.firstFrame=1;
nixnax	175:b4e6f8a6fe00	182	ppp.ppp = (pppHeaderType *)ppp.pkt.buf; // pointer to ppp header
nixnax	175:b4e6f8a6fe00	183	ppp.ip = (ipHeaderType *)(ppp.pkt.buf+4); // pointer to IP header
nixnax	142:54d1543e23e5	184	}
nixnax	142:54d1543e23e5	185
nixnax	142:54d1543e23e5	186	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	187	void led1Toggle()
nixnax	142:54d1543e23e5	188	{
nixnax	142:54d1543e23e5	189	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	190	ppp.ledState++;
nixnax	142:54d1543e23e5	191	}
nixnax	142:54d1543e23e5	192
nixnax	179:ba2b2ddd0da5	193	/// Returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax	150:3366bf3d294e	194	int connectedPpp()
nixnax	142:54d1543e23e5	195	{
nixnax	142:54d1543e23e5	196	return ppp.online;
nixnax	143:c5019f856a56	197	}
nixnax	142:54d1543e23e5	198
nixnax	179:ba2b2ddd0da5	199	/// PPP serial port receive interrupt handler.
nixnax	143:c5019f856a56	200	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	201	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	179:ba2b2ddd0da5	202	void pppReceiveHandler()
nixnax	142:54d1543e23e5	203	{
nixnax	142:54d1543e23e5	204	char ch;
nixnax	179:ba2b2ddd0da5	205	while ( pc.readable() ) {
nixnax	142:54d1543e23e5	206	int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax	142:54d1543e23e5	207	if ( hd == ppp.rx.rtail ) {
nixnax	142:54d1543e23e5	208	debugPrintf("\nReceive buffer full\n");
nixnax	142:54d1543e23e5	209	return;
nixnax	142:54d1543e23e5	210	}
nixnax	142:54d1543e23e5	211	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	212	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	205:c730866cb598	213	if (ch == 0x7E) { // check for ppp frame start character
nixnax	205:c730866cb598	214	if ( ppp.online == 0 ) { // check if we are offline
nixnax	205:c730866cb598	215	ppp.online = 1; // if we see a frame start character we immediately change status to online
nixnax	142:54d1543e23e5	216	}
nixnax	142:54d1543e23e5	217	}
nixnax	142:54d1543e23e5	218	ppp.rx.head = hd; // update head pointer
nixnax	142:54d1543e23e5	219	ppp.rx.buflevel++;
nixnax	205:c730866cb598	220	if ( ppp.rx.buflevel > ppp.rx.maxbuflevel ) {
nixnax	205:c730866cb598	221	ppp.rx.maxbuflevel = ppp.rx.buflevel; // remember the max size of rx buflevel
nixnax	205:c730866cb598	222	}
nixnax	142:54d1543e23e5	223	}
nixnax	142:54d1543e23e5	224	}
nixnax	142:54d1543e23e5	225
nixnax	142:54d1543e23e5	226	/// print to debug port while checking for incoming characters
nixnax	142:54d1543e23e5	227	void putcWhileCheckingInput( char outByte )
nixnax	142:54d1543e23e5	228	{
nixnax	142:54d1543e23e5	229	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	230	debugPutc( outByte );
nixnax	142:54d1543e23e5	231	#endif
nixnax	142:54d1543e23e5	232	}
nixnax	142:54d1543e23e5	233
nixnax	142:54d1543e23e5	234	/// puts to debug port while checking the PPP input stream
nixnax	142:54d1543e23e5	235	void putsWhileCheckingInput( char * data )
nixnax	142:54d1543e23e5	236	{
nixnax	142:54d1543e23e5	237	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	238	char * nextChar = data;
nixnax	142:54d1543e23e5	239	while( *nextChar != 0 ) {
nixnax	142:54d1543e23e5	240	putcWhileCheckingInput( *nextChar ); // write one character to debug port while checking input
nixnax	142:54d1543e23e5	241	nextChar++;
nixnax	142:54d1543e23e5	242	}
nixnax	142:54d1543e23e5	243	#endif
nixnax	142:54d1543e23e5	244	}
nixnax	142:54d1543e23e5	245
nixnax	145:098b6ed2f7f2	246	/// Initialize the PPP FCS (frame check sequence) total
nixnax	145:098b6ed2f7f2	247	void fcsReset()
nixnax	142:54d1543e23e5	248	{
nixnax	145:098b6ed2f7f2	249	ppp.fcs=0xffff; // crc restart
nixnax	142:54d1543e23e5	250	}
nixnax	142:54d1543e23e5	251
nixnax	145:098b6ed2f7f2	252	/// update the cumulative PPP FCS (frame check sequence)
nixnax	145:098b6ed2f7f2	253	void fcsDo(int x)
nixnax	142:54d1543e23e5	254	{
nixnax	142:54d1543e23e5	255	for (int i=0; i<8; i++) {
nixnax	145:098b6ed2f7f2	256	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1; // crc calculator
nixnax	142:54d1543e23e5	257	x>>=1;
nixnax	142:54d1543e23e5	258	}
nixnax	205:c730866cb598	259
nixnax	142:54d1543e23e5	260	}
nixnax	142:54d1543e23e5	261
nixnax	145:098b6ed2f7f2	262	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	263	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	264	{
nixnax	145:098b6ed2f7f2	265	fcsReset();
nixnax	145:098b6ed2f7f2	266	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	267	return ppp.fcs;
nixnax	142:54d1543e23e5	268	}
nixnax	142:54d1543e23e5	269
nixnax	142:54d1543e23e5	270	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	271	int pc_getBuf()
nixnax	142:54d1543e23e5	272	{
nixnax	142:54d1543e23e5	273	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	142:54d1543e23e5	274	ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax	142:54d1543e23e5	275	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	276	return x;
nixnax	142:54d1543e23e5	277	}
nixnax	142:54d1543e23e5	278
nixnax	142:54d1543e23e5	279	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	280	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	281	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	164:c3de3d212c4b	282	/// In WireShark, use "Import Hex File". Import options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	283	void dumpPPPFrame()
nixnax	142:54d1543e23e5	284	{
nixnax	142:54d1543e23e5	285	char pbuf[30];
nixnax	142:54d1543e23e5	286	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	205:c730866cb598	287
nixnax	142:54d1543e23e5	288	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	205:c730866cb598	289
nixnax	142:54d1543e23e5	290	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	291	}
nixnax	205:c730866cb598	292
nixnax	142:54d1543e23e5	293	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	205:c730866cb598	294
nixnax	142:54d1543e23e5	295	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	296	}
nixnax	142:54d1543e23e5	297
nixnax	142:54d1543e23e5	298	/// Process a received PPP frame
nixnax	142:54d1543e23e5	299	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	300	{
nixnax	142:54d1543e23e5	301	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	302	if(start==end) {
nixnax	142:54d1543e23e5	303	return; // empty frame
nixnax	142:54d1543e23e5	304	}
nixnax	145:098b6ed2f7f2	305	fcsReset();
nixnax	142:54d1543e23e5	306	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	307	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	308	int unstuff=0;
nixnax	142:54d1543e23e5	309	int idx = start;
nixnax	142:54d1543e23e5	310	while(1) {
nixnax	205:c730866cb598	311
nixnax	142:54d1543e23e5	312	if (unstuff==0) {
nixnax	142:54d1543e23e5	313	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	314	else {
nixnax	142:54d1543e23e5	315	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	316	ppp.pkt.len++;
nixnax	142:54d1543e23e5	317	dest++;
nixnax	145:098b6ed2f7f2	318	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	319	}
nixnax	142:54d1543e23e5	320	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	321	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	322	ppp.pkt.len++;
nixnax	142:54d1543e23e5	323	dest++;
nixnax	145:098b6ed2f7f2	324	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	325	unstuff=0;
nixnax	142:54d1543e23e5	326	}
nixnax	142:54d1543e23e5	327	idx = (idx+1) & (RXBUFLEN-1);
nixnax	142:54d1543e23e5	328	if (idx == end) break;
nixnax	142:54d1543e23e5	329	}
nixnax	145:098b6ed2f7f2	330	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	331	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	332	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	333	determinePacketType();
nixnax	142:54d1543e23e5	334	} else {
nixnax	142:54d1543e23e5	335	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	336	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	337	char pbuf[50]; // local print buffer
nixnax	205:c730866cb598	338
nixnax	142:54d1543e23e5	339	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	205:c730866cb598	340
nixnax	142:54d1543e23e5	341	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	342	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	343	#endif
nixnax	142:54d1543e23e5	344	}
nixnax	142:54d1543e23e5	345	}
nixnax	142:54d1543e23e5	346
nixnax	142:54d1543e23e5	347	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	348	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	349	{
nixnax	205:c730866cb598	350
nixnax	142:54d1543e23e5	351	pc.putc(ch);
nixnax	205:c730866cb598	352
nixnax	142:54d1543e23e5	353	}
nixnax	142:54d1543e23e5	354
nixnax	142:54d1543e23e5	355	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	356	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	357	{
nixnax	142:54d1543e23e5	358	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	359	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	360	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	361	} else {
nixnax	142:54d1543e23e5	362	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	363	}
nixnax	142:54d1543e23e5	364	}
nixnax	142:54d1543e23e5	365
nixnax	142:54d1543e23e5	366	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	367	void sendPppFrame()
nixnax	143:c5019f856a56	368	{
nixnax	172:449dd7a28955	369	ppp.responseCounter++; // count the number of ppp frames we send
nixnax	145:098b6ed2f7f2	370	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	371	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	372	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	373	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	374	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	375	wait_us(86); // wait one character time
nixnax	205:c730866cb598	376
nixnax	142:54d1543e23e5	377	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	378	}
nixnax	142:54d1543e23e5	379	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	380	}
nixnax	142:54d1543e23e5	381
nixnax	143:c5019f856a56	382	/// 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	383	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	384	{
nixnax	143:c5019f856a56	385	int result=0;
nixnax	143:c5019f856a56	386	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	387	return result;
nixnax	143:c5019f856a56	388	}
nixnax	143:c5019f856a56	389
nixnax	177:dab9e685af53	390	/// convert 4-byte ip address to 32-bit
nixnax	179:ba2b2ddd0da5	391	unsigned int ip( int a, int b, int c, int d)
nixnax	179:ba2b2ddd0da5	392	{
nixnax	177:dab9e685af53	393	return a<<24 \| b<<16 \| c<<8 \| d;
nixnax	177:dab9e685af53	394	}
nixnax	177:dab9e685af53	395
nixnax	142:54d1543e23e5	396	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	397	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	398	{
nixnax	142:54d1543e23e5	399	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	173:6774a0c851c4	400	if(ppp.ipcp->request[0]==3) {
nixnax	143:c5019f856a56	401	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	173:6774a0c851c4	402	debugPrintf("Host IP = %d.%d.%d.%d (%08x)\n", ppp.ipcp->request[2],ppp.ipcp->request[3],ppp.ipcp->request[4],ppp.ipcp->request[5],ppp.hostIP);
nixnax	143:c5019f856a56	403	}
nixnax	143:c5019f856a56	404
nixnax	167:ff8a2d8beeb1	405	ppp.ipcp->code=2; // change code to ack
nixnax	144:01d98cf7738e	406	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	407
nixnax	142:54d1543e23e5	408	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	167:ff8a2d8beeb1	409	ppp.ipcp->code=1; // change code to request
nixnax	167:ff8a2d8beeb1	410	ppp.ipcp->lengthR = __REV16( 4 ); // 4 is minimum length - no options in this request
nixnax	167:ff8a2d8beeb1	411	ppp.pkt.len=4+4+2; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	412	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	413	}
nixnax	142:54d1543e23e5	414
nixnax	142:54d1543e23e5	415	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	416	void ipcpAckHandler()
nixnax	142:54d1543e23e5	417	{
nixnax	142:54d1543e23e5	418	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	419	}
nixnax	142:54d1543e23e5	420
nixnax	143:c5019f856a56	421	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	422	/// 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	423	void ipcpNackHandler()
nixnax	142:54d1543e23e5	424	{
nixnax	146:a45f49a2b29c	425	debugPrintf("Their IPCP Nack\n");
nixnax	173:6774a0c851c4	426	if (ppp.ipcp->request[0]==3) { // check if the NACK contains an IP address parameter
nixnax	167:ff8a2d8beeb1	427	ppp.ipcp->code=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	428	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	429	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	430	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	431	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	432	}
nixnax	142:54d1543e23e5	433	}
nixnax	142:54d1543e23e5	434
nixnax	142:54d1543e23e5	435	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	436	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	437	{
nixnax	142:54d1543e23e5	438	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	439	}
nixnax	142:54d1543e23e5	440
nixnax	142:54d1543e23e5	441	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	442	void IPCPframe()
nixnax	142:54d1543e23e5	443	{
nixnax	167:ff8a2d8beeb1	444	int action = ppp.ipcp->code; // packet type is here
nixnax	167:ff8a2d8beeb1	445	switch (action) {
nixnax	142:54d1543e23e5	446	case 1:
nixnax	142:54d1543e23e5	447	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	448	break;
nixnax	142:54d1543e23e5	449	case 2:
nixnax	142:54d1543e23e5	450	ipcpAckHandler();
nixnax	142:54d1543e23e5	451	break;
nixnax	142:54d1543e23e5	452	case 3:
nixnax	142:54d1543e23e5	453	ipcpNackHandler();
nixnax	142:54d1543e23e5	454	break;
nixnax	142:54d1543e23e5	455	default:
nixnax	142:54d1543e23e5	456	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	457	}
nixnax	142:54d1543e23e5	458	}
nixnax	142:54d1543e23e5	459
nixnax	142:54d1543e23e5	460	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	161:d59f778bc8ab	461	unsigned int dataCheckSum(char * ptr, int len, int restart)
nixnax	142:54d1543e23e5	462	{
nixnax	159:4d1bf96a59cd	463	unsigned int i,hi,lo;
nixnax	142:54d1543e23e5	464	unsigned char placeHolder;
nixnax	161:d59f778bc8ab	465	if (restart) ppp.sum=0;
nixnax	142:54d1543e23e5	466	if (len&1) {
nixnax	142:54d1543e23e5	467	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	468	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	469	}
nixnax	142:54d1543e23e5	470	i=0;
nixnax	142:54d1543e23e5	471	while ( i<len ) {
nixnax	205:c730866cb598	472
nixnax	142:54d1543e23e5	473	hi = ptr[i++];
nixnax	142:54d1543e23e5	474	lo = ptr[i++];
nixnax	159:4d1bf96a59cd	475	ppp.sum = ppp.sum + ((hi<<8)\|lo);
nixnax	142:54d1543e23e5	476	}
nixnax	142:54d1543e23e5	477	if (len&1) {
nixnax	142:54d1543e23e5	478	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	479	}
nixnax	159:4d1bf96a59cd	480	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax	159:4d1bf96a59cd	481	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax	159:4d1bf96a59cd	482	return ~ppp.sum;
nixnax	142:54d1543e23e5	483	}
nixnax	142:54d1543e23e5	484
nixnax	142:54d1543e23e5	485	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	486	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	487	{
nixnax	161:d59f778bc8ab	488	ppp.ip->checksumR=0; // zero the checsum in the IP header
nixnax	161:d59f778bc8ab	489	int len = 4 * ppp.ip->headerLength; // length of IP header in bytes
nixnax	161:d59f778bc8ab	490	unsigned int sum = dataCheckSum(ppp.ipStart,len,1);
nixnax	161:d59f778bc8ab	491	ppp.ip->checksumR = __REV16( sum ); // insert fresh checksum
nixnax	146:a45f49a2b29c	492	}
nixnax	146:a45f49a2b29c	493
nixnax	147:0f40005cbc5f	494	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	495	void swapIpAddresses()
nixnax	147:0f40005cbc5f	496	{
nixnax	162:594729c0e5c1	497	unsigned int tempHold;
nixnax	162:594729c0e5c1	498	tempHold = ppp.ip->srcAdrR; // tempHold <- source IP
nixnax	162:594729c0e5c1	499	ppp.ip->srcAdrR = ppp.ip->dstAdrR; // source <- dest
nixnax	162:594729c0e5c1	500	ppp.ip->dstAdrR = tempHold; // dest <- tempHold*/
nixnax	147:0f40005cbc5f	501	}
nixnax	147:0f40005cbc5f	502
nixnax	149:969d98f6fb88	503	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	504	void swapIpPorts()
nixnax	149:969d98f6fb88	505	{
nixnax	173:6774a0c851c4	506	int headerSizeIP = 4 * (ppp.ip->headerLength); // calculate size of IP header
nixnax	173:6774a0c851c4	507	char * ipSrcPort = ppp.ipStart + headerSizeIP + 0; // ip source port location
nixnax	173:6774a0c851c4	508	char * ipDstPort = ppp.ipStart + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	509	char tempHold[2];
nixnax	149:969d98f6fb88	510	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	511	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	512	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	513	}
nixnax	149:969d98f6fb88	514
nixnax	170:3d3b2126181c	515	/// Build the "pseudo header" required for UDP and TCP, then calculate its checksum
nixnax	170:3d3b2126181c	516	void checkSumPseudoHeader( unsigned int packetLength )
nixnax	170:3d3b2126181c	517	{
nixnax	170:3d3b2126181c	518	// this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax	170:3d3b2126181c	519	pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax	170:3d3b2126181c	520	pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax	170:3d3b2126181c	521	pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax	170:3d3b2126181c	522	pseudoHeader.zero = 0; // zero byte
nixnax	170:3d3b2126181c	523	pseudoHeader.protocol = ppp.ip->protocol; // protocol number (udp or tcp)
nixnax	170:3d3b2126181c	524	pseudoHeader.lengthR = __REV16( packetLength ); // size of tcp or udp packet
nixnax	170:3d3b2126181c	525	dataCheckSum(pseudoHeader.start, 12, 1); // calculate this header's checksum
nixnax	170:3d3b2126181c	526	}
nixnax	170:3d3b2126181c	527
nixnax	171:46b36d4edd1d	528	/// initialize an IP packet to send
nixnax	171:46b36d4edd1d	529	void initIP (unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, unsigned int protocol)
nixnax	171:46b36d4edd1d	530	{
nixnax	171:46b36d4edd1d	531	ppp.ppp->address = 0xff;
nixnax	171:46b36d4edd1d	532	ppp.ppp->control = 3;
nixnax	171:46b36d4edd1d	533	ppp.ppp->protocolR = __REV16( 0x0021 );
nixnax	171:46b36d4edd1d	534	ppp.ip->version = 4;
nixnax	171:46b36d4edd1d	535	ppp.ip->headerLength = 5; // 5 words = 20 bytes
nixnax	171:46b36d4edd1d	536	ppp.ip->identR = __REV16(ppp.ipData.ident++); // insert our ident
nixnax	171:46b36d4edd1d	537	ppp.ip->dontFragment=1;
nixnax	171:46b36d4edd1d	538	ppp.ip->ttl=128;
nixnax	171:46b36d4edd1d	539	ppp.ip->protocol = protocol; // udp
nixnax	171:46b36d4edd1d	540	ppp.ip->srcAdrR = __REV(srcIp);
nixnax	171:46b36d4edd1d	541	ppp.ip->dstAdrR = __REV(dstIp);
nixnax	171:46b36d4edd1d	542	ppp.udpStart = ppp.ipStart + 20; // calculate start of udp header
nixnax	171:46b36d4edd1d	543	ppp.udp->srcPortR = __REV16(srcPort); // source port
nixnax	171:46b36d4edd1d	544	ppp.udp->dstPortR = __REV16(dstPort); // dest port
nixnax	171:46b36d4edd1d	545	}
nixnax	171:46b36d4edd1d	546
nixnax	171:46b36d4edd1d	547
nixnax	171:46b36d4edd1d	548	/// Build a UDP packet from scratch
nixnax	171:46b36d4edd1d	549	void sendUdp(unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, char * message,int msgLen)
nixnax	171:46b36d4edd1d	550	{
nixnax	171:46b36d4edd1d	551	struct {
nixnax	171:46b36d4edd1d	552	unsigned int ipAll; // length of entire ip packet
nixnax	171:46b36d4edd1d	553	unsigned int ipHeader; // length of ip header
nixnax	171:46b36d4edd1d	554	unsigned int udpAll; // length of entire udp packet
nixnax	171:46b36d4edd1d	555	unsigned int udpData; // length of udp data segment
nixnax	171:46b36d4edd1d	556	} len;
nixnax	171:46b36d4edd1d	557	len.ipHeader = 20; // ip header length
nixnax	171:46b36d4edd1d	558	len.udpData = msgLen; // udp data size
nixnax	171:46b36d4edd1d	559	len.udpAll = len.udpData+8; // update local udp packet length
nixnax	171:46b36d4edd1d	560	len.ipAll = len.ipHeader + len.udpAll; // update IP Length
nixnax	171:46b36d4edd1d	561	initIP(srcIp, dstIp, srcPort, dstPort, 17); // init a UDP packet
nixnax	171:46b36d4edd1d	562	ppp.ip->lengthR = __REV16(len.ipAll); // update IP length in buffer
nixnax	171:46b36d4edd1d	563	ppp.udpStart = ppp.ipStart + len.ipHeader; // calculate start of udp header
nixnax	171:46b36d4edd1d	564	memcpy( ppp.udp->data, message, len.udpData ); // copy the message to the buffer
nixnax	171:46b36d4edd1d	565	ppp.udp->lengthR = __REV16(len.udpAll); // update UDP length in buffer
nixnax	171:46b36d4edd1d	566	ppp.pkt.len = len.ipAll+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	567	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	568	checkSumPseudoHeader( len.udpAll ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	569	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	570	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,len.udpAll, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	571	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	572	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	573	}
nixnax	171:46b36d4edd1d	574
nixnax	146:a45f49a2b29c	575	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	576	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	577	void UDPpacket()
nixnax	146:a45f49a2b29c	578	{
nixnax	163:d1b4328e9f08	579	struct {
nixnax	163:d1b4328e9f08	580	unsigned int all; // length of entire ip packet
nixnax	163:d1b4328e9f08	581	unsigned int header; // length of ip header
nixnax	163:d1b4328e9f08	582	} ipLength;
nixnax	163:d1b4328e9f08	583
nixnax	163:d1b4328e9f08	584	struct {
nixnax	165:c47826d07e0d	585	unsigned int all; // length of entire udp packet
nixnax	163:d1b4328e9f08	586	unsigned int data; // length of udp data segment
nixnax	163:d1b4328e9f08	587	} udpLength;
nixnax	163:d1b4328e9f08	588
nixnax	163:d1b4328e9f08	589	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	163:d1b4328e9f08	590	ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	171:46b36d4edd1d	591	udpLength.all = __REV16( ppp.udp->lengthR ); // size of udp packet
nixnax	163:d1b4328e9f08	592	udpLength.data = udpLength.all - 8; // size of udp data
nixnax	147:0f40005cbc5f	593
nixnax	146:a45f49a2b29c	594	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	171:46b36d4edd1d	595	char * srcIP = ppp.ip->srcAdrPtr; // IP source
nixnax	171:46b36d4edd1d	596	char * dstIP = ppp.ip->dstAdrPtr; //IP destination
nixnax	163:d1b4328e9f08	597
nixnax	171:46b36d4edd1d	598	unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); // integer of UDP source port
nixnax	171:46b36d4edd1d	599	unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); // integer of UDP dest port
nixnax	163:d1b4328e9f08	600
nixnax	163:d1b4328e9f08	601	if(v0) {
nixnax	163:d1b4328e9f08	602	debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
nixnax	163:d1b4328e9f08	603	debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
nixnax	163:d1b4328e9f08	604	debugPrintf("Len %03d", udpLength);
nixnax	163:d1b4328e9f08	605	}
nixnax	146:a45f49a2b29c	606	if (v1) {
nixnax	163:d1b4328e9f08	607	int printSize = udpLength.data;
nixnax	146:a45f49a2b29c	608	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	609	for (int i=0; i<printSize; i++) {
nixnax	163:d1b4328e9f08	610	char ch = ppp.udp->data[i];
nixnax	146:a45f49a2b29c	611	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	612	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	613	} else {
nixnax	146:a45f49a2b29c	614	debugPrintf("_");
nixnax	146:a45f49a2b29c	615	}
nixnax	146:a45f49a2b29c	616	}
nixnax	146:a45f49a2b29c	617	}
nixnax	146:a45f49a2b29c	618	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	619	#endif
nixnax	163:d1b4328e9f08	620	int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
nixnax	163:d1b4328e9f08	621	int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	622	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	146:a45f49a2b29c	623	if (echoFound) {
nixnax	171:46b36d4edd1d	624	swapIpAddresses(); // swap IP source and destination
nixnax	171:46b36d4edd1d	625	swapIpPorts(); // swap IP source and destination ports
nixnax	163:d1b4328e9f08	626	memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	170:3d3b2126181c	627	int n=0;
nixnax	170:3d3b2126181c	628	n=n+sprintf(n+ppp.udp->data+udpLength.data, "} UDP Server: PPP-Blinky\n"); // an appendix
nixnax	168:c77eb908042a	629	udpLength.data = udpLength.data + n; // update udp data size with the size of the appendix
nixnax	171:46b36d4edd1d	630	// we may have changed data length, update all the lengths
nixnax	171:46b36d4edd1d	631	udpLength.all = udpLength.data+8; // update local udp packet length
nixnax	171:46b36d4edd1d	632	ipLength.all = ipLength.header + udpLength.all; // update IP Length
nixnax	171:46b36d4edd1d	633	ppp.ip->lengthR = __REV16(ipLength.all); // update IP length in buffer
nixnax	171:46b36d4edd1d	634	ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
nixnax	171:46b36d4edd1d	635	ppp.pkt.len = ipLength.all+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	636	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	637	checkSumPseudoHeader( udpLength.all ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	638	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	639	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,udpLength.all, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	640	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	641	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	642	} else if ( testFound ) {
nixnax	171:46b36d4edd1d	643	unsigned int sI = __REV( ppp.ip->srcAdrR );
nixnax	171:46b36d4edd1d	644	unsigned int dI = __REV( ppp.ip->dstAdrR );
nixnax	171:46b36d4edd1d	645	unsigned int sp = __REV16( ppp.udp->srcPortR );
nixnax	171:46b36d4edd1d	646	unsigned int dp = __REV16( ppp.udp->dstPortR );
nixnax	172:449dd7a28955	647	int n=sprintf(ppp.pkt.buf+200,"Response Count %d\n", ppp.responseCounter);
nixnax	171:46b36d4edd1d	648	sendUdp(dI,sI,dp,sp,ppp.pkt.buf+200,n); // build a udp packet from the ground up
nixnax	146:a45f49a2b29c	649	}
nixnax	146:a45f49a2b29c	650	}
nixnax	142:54d1543e23e5	651	}
nixnax	142:54d1543e23e5	652
nixnax	174:e5a3f16421a5	653	/// UDP demo that sends a udp packet containing a character received from the second debug serial port.
nixnax	174:e5a3f16421a5	654	/// Sends a 48 byte IP/UDP header for every 1 byte of data so line-mode would probably be better.
nixnax	178:3f17aa0ce5ce	655	/// If you want ip packets from ppp blinky to be routed to other networks, ensure you have ip routing enabled.
nixnax	178:3f17aa0ce5ce	656	/// See http://www.wikihow.com/Enable-IP-Routing.
nixnax	179:ba2b2ddd0da5	657	/// Also ensure that the firewall on the receiving machine has the receiving UDP port (12345 in this example) enabled.
nixnax	179:ba2b2ddd0da5	658	/// The netcat UDP receive command on the remote host would be: nc -ul 12345
nixnax	174:e5a3f16421a5	659	void sendUdpData()
nixnax	174:e5a3f16421a5	660	{
nixnax	174:e5a3f16421a5	661	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	179:ba2b2ddd0da5	662	if (ppp.online) {
nixnax	179:ba2b2ddd0da5	663	if (xx.readable()) {
nixnax	179:ba2b2ddd0da5	664	char inchar = xx.getc();
nixnax	179:ba2b2ddd0da5	665	xx.putc( inchar ); // echo the received character on the debug serial port
nixnax	179:ba2b2ddd0da5	666	sendUdp(ip(172,10,10,2), ip(192,168,0,109), 1, 12345, &inchar, 1); // send a 1 byte UDP message to a remote machine at IP 192.168.0.109:12345
nixnax	179:ba2b2ddd0da5	667	}
nixnax	174:e5a3f16421a5	668	}
nixnax	174:e5a3f16421a5	669	#endif
nixnax	174:e5a3f16421a5	670	}
nixnax	174:e5a3f16421a5	671
nixnax	142:54d1543e23e5	672	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	673	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	674	{
nixnax	165:c47826d07e0d	675	struct {
nixnax	165:c47826d07e0d	676	unsigned int all; // length of entire ip packet
nixnax	165:c47826d07e0d	677	unsigned int header; // length of ip header
nixnax	165:c47826d07e0d	678	} ipLength;
nixnax	165:c47826d07e0d	679	struct {
nixnax	165:c47826d07e0d	680	unsigned int all; // length of entire udp packet
nixnax	165:c47826d07e0d	681	unsigned int data; // length of udp data segment
nixnax	165:c47826d07e0d	682	} icmpLength;
nixnax	165:c47826d07e0d	683	ipLength.all = __REV16( ppp.ip->lengthR ); // length of ip packet
nixnax	165:c47826d07e0d	684	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	165:c47826d07e0d	685	ppp.icmpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	165:c47826d07e0d	686	icmpLength.all = ipLength.all - ipLength.header; // length of icmp packet
nixnax	165:c47826d07e0d	687	icmpLength.data = icmpLength.all - 8; // length of icmp data
nixnax	142:54d1543e23e5	688	#define ICMP_TYPE_PING_REQUEST 8
nixnax	165:c47826d07e0d	689	if ( ppp.icmp->type == ICMP_TYPE_PING_REQUEST ) {
nixnax	165:c47826d07e0d	690	ppp.ip->ttl--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	691	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	167:ff8a2d8beeb1	692	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	693	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	165:c47826d07e0d	694	int icmpIdent = __REV16( ppp.ip->identR ); // byte reversed - big endian
nixnax	165:c47826d07e0d	695	int icmpSequence = __REV16( ppp.icmp->sequenceR ); // byte reversed - big endian
nixnax	142:54d1543e23e5	696	if(1) {
nixnax	142:54d1543e23e5	697	char pbuf[50];
nixnax	205:c730866cb598	698
nixnax	142:54d1543e23e5	699	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	700	putsWhileCheckingInput( pbuf );
nixnax	205:c730866cb598	701
nixnax	142:54d1543e23e5	702	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	205:c730866cb598	703
nixnax	142:54d1543e23e5	704	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	705	}
nixnax	142:54d1543e23e5	706	#endif
nixnax	147:0f40005cbc5f	707	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	708	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	709	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	165:c47826d07e0d	710	ppp.icmp->type = ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	165:c47826d07e0d	711	ppp.icmp->checkSumR = 0; // zero the checksum for recalculation
nixnax	165:c47826d07e0d	712	unsigned int sum = dataCheckSum(ppp.icmpStart, icmpLength.all, 1); // icmp checksum
nixnax	165:c47826d07e0d	713	ppp.icmp->checkSumR = __REV16( sum ); // save big-endian icmp checksum
nixnax	142:54d1543e23e5	714
nixnax	165:c47826d07e0d	715	int printSize = icmpLength.data; // exclude size of icmp header
nixnax	142:54d1543e23e5	716	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	717	if (0) {
nixnax	142:54d1543e23e5	718	for (int i=0; i<printSize; i++) {
nixnax	165:c47826d07e0d	719	char ch = ppp.icmp->data[i];
nixnax	142:54d1543e23e5	720	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	721	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	722	} else {
nixnax	142:54d1543e23e5	723	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	724	}
nixnax	142:54d1543e23e5	725	}
nixnax	142:54d1543e23e5	726	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	727	}
nixnax	144:01d98cf7738e	728	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	729	} else {
nixnax	142:54d1543e23e5	730	if (v0) {
nixnax	165:c47826d07e0d	731	debugPrintf("ICMP type=%x \n", ppp.icmp->type);
nixnax	142:54d1543e23e5	732	}
nixnax	142:54d1543e23e5	733	}
nixnax	142:54d1543e23e5	734	}
nixnax	142:54d1543e23e5	735
nixnax	142:54d1543e23e5	736	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	737	void IGMPpacket()
nixnax	142:54d1543e23e5	738	{
nixnax	142:54d1543e23e5	739	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	740	}
nixnax	142:54d1543e23e5	741
nixnax	142:54d1543e23e5	742	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	743	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	744	{
nixnax	142:54d1543e23e5	745	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	205:c730866cb598	746
nixnax	155:9c6a1d249e26	747	int IPv4Id = __REV16(ppp.ip->identR);
nixnax	152:025c73b6c0a9	748	char pbuf[80]; // local print buffer
nixnax	142:54d1543e23e5	749	int n=0;
nixnax	142:54d1543e23e5	750	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	751	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	752	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	753	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	167:ff8a2d8beeb1	754	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	755	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	142:54d1543e23e5	756	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	757	#endif
nixnax	142:54d1543e23e5	758	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	759	#ifndef TCP_HEADER_DUMP_YES
nixnax	160:bd701ad564cb	760	putsWhileCheckingInput('\x1b[30m\n'); // if there's no TCP header dump we terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	761	#endif
nixnax	142:54d1543e23e5	762	#endif
nixnax	142:54d1543e23e5	763	}
nixnax	142:54d1543e23e5	764
nixnax	142:54d1543e23e5	765	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	766	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	767	{
nixnax	142:54d1543e23e5	768	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	155:9c6a1d249e26	769	char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	770	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	771	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	155:9c6a1d249e26	772	memset(flagString,'.', 8); // fill string with "........"
nixnax	156:163c23249731	773	if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax	156:163c23249731	774	if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax	156:163c23249731	775	if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax	156:163c23249731	776	if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax	156:163c23249731	777	if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax	156:163c23249731	778	if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax	156:163c23249731	779	if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax	156:163c23249731	780	if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax	155:9c6a1d249e26	781	flagString[8]=0; // null terminate string
nixnax	142:54d1543e23e5	782	#else
nixnax	156:163c23249731	783	if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax	156:163c23249731	784	if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax	156:163c23249731	785	if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax	156:163c23249731	786	if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax	156:163c23249731	787	if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax	155:9c6a1d249e26	788	flagString[1]=0; // null terminate string
nixnax	142:54d1543e23e5	789	#endif
nixnax	155:9c6a1d249e26	790	putsWhileCheckingInput( flagString );
nixnax	142:54d1543e23e5	791	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	792	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	793	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	160:bd701ad564cb	794	#else
nixnax	160:bd701ad564cb	795	putsWhileCheckingInput("\x1b[30m"); // write a black color after every packet
nixnax	142:54d1543e23e5	796	#endif
nixnax	156:163c23249731	797	if( outGoing && ppp.tcp->flag.fin ) { // ACK/FIN - if this is an outgoing FIN it's the end of a tcp conversation
nixnax	160:bd701ad564cb	798	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end (except for final ack) of an HTTP conversation
nixnax	142:54d1543e23e5	799	}
nixnax	142:54d1543e23e5	800	#endif
nixnax	142:54d1543e23e5	801	}
nixnax	142:54d1543e23e5	802
nixnax	143:c5019f856a56	803	/// Encode a buffer in base-64
nixnax	184:4133f557d4d4	804	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	805	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	806	{
nixnax	142:54d1543e23e5	807	int i,j,a,b,c;
nixnax	142:54d1543e23e5	808	i=0;
nixnax	142:54d1543e23e5	809	j=0;
nixnax	142:54d1543e23e5	810	while(1) {
nixnax	142:54d1543e23e5	811	if (i<len) {
nixnax	142:54d1543e23e5	812	a = in[i++];
nixnax	142:54d1543e23e5	813	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	814	} else break;
nixnax	142:54d1543e23e5	815	if (i<len) {
nixnax	142:54d1543e23e5	816	b = in[i++];
nixnax	142:54d1543e23e5	817	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	818	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	819	} else out[j++] = '=';
nixnax	142:54d1543e23e5	820	if (i<len) {
nixnax	142:54d1543e23e5	821	c = in[i++];
nixnax	142:54d1543e23e5	822	j--;
nixnax	142:54d1543e23e5	823	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	824	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	825	} else out[j++] = '=';
nixnax	142:54d1543e23e5	826	}
nixnax	142:54d1543e23e5	827	out[j]=0;
nixnax	142:54d1543e23e5	828	}
nixnax	142:54d1543e23e5	829
nixnax	160:bd701ad564cb	830	/// Handle a request for an http websocket.
nixnax	160:bd701ad564cb	831	/// 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	832	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	833	{
nixnax	142:54d1543e23e5	834	int n=0; // byte counter
nixnax	184:4133f557d4d4	835	char * key = strstr(dataStart, "Sec-WebSocket-Key:"); // search for the key in the payload
nixnax	142:54d1543e23e5	836	if (key != NULL) {
nixnax	184:4133f557d4d4	837	key = key + 18; // skip over the key ident string "Sec-WebSocket-Key:"
nixnax	142:54d1543e23e5	838	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	184:4133f557d4d4	839	while ( strchr(lut, *key) == NULL) key++; // skip non-valid base-64 characters (whitespace)
nixnax	184:4133f557d4d4	840	char challenge [80];
nixnax	184:4133f557d4d4	841	int i=0;
nixnax	184:4133f557d4d4	842	char * copyTo = challenge;
nixnax	184:4133f557d4d4	843	while (strchr(lut, *key) != NULL) { // copy while we see valid base-64 characters
nixnax	184:4133f557d4d4	844	if (i++ >40) break; // prevent buffer overflow
nixnax	184:4133f557d4d4	845	copyTo++ = key++; // copy next valid base-64 character
nixnax	184:4133f557d4d4	846	}
nixnax	184:4133f557d4d4	847	strcpy(copyTo,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"); // append websocket gui code
nixnax	184:4133f557d4d4	848	if (0) debugPrintf("Challenge is %s\n", challenge); // the string we hash for the challenge
nixnax	142:54d1543e23e5	849	char shaOutput [20]; // sha1 output
nixnax	184:4133f557d4d4	850	sha1( shaOutput, challenge, strlen(challenge)); // hash the challenge
nixnax	142:54d1543e23e5	851	char encOut[50];
nixnax	184:4133f557d4d4	852	enc64( shaOutput, encOut, 20); // base-64 encode
nixnax	142:54d1543e23e5	853	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	854	char * version = challenge;
nixnax	184:4133f557d4d4	855	strncpy(version, versionstring,70); // copy their version string
nixnax	142:54d1543e23e5	856	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	857	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	858	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	859	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	860	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	861	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	862	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	863	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	864	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	865	}
nixnax	142:54d1543e23e5	866	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	867	}
nixnax	142:54d1543e23e5	868
nixnax	142:54d1543e23e5	869	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	870	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	871	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	872	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	873	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	874
nixnax	142:54d1543e23e5	875	/// respond to an HTTP request
nixnax	185:4cd8f91e9d49	876	int httpResponse(char * dataStart, int * flags)
nixnax	142:54d1543e23e5	877	{
nixnax	142:54d1543e23e5	878	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	879	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	160:bd701ad564cb	880	if (n>0) return n; // if n>0 we already have a response, so return
nixnax	142:54d1543e23e5	881
nixnax	142:54d1543e23e5	882	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	883	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	884	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	185:4cd8f91e9d49	885	*flags = TCP_FLAG_ACK \| TCP_FLAG_FIN; // the default case is that we close the connection
nixnax	142:54d1543e23e5	886
nixnax	142:54d1543e23e5	887	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	888	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	889	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	890	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	891	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	142:54d1543e23e5	892	if( (httpGetRoot==0) \|\| (httpGetx==0) ) {
nixnax	142:54d1543e23e5	893	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	894	} else {
nixnax	142:54d1543e23e5	895	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	896	}
nixnax	142:54d1543e23e5	897	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	898	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	899	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	900	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	205:c730866cb598	901	#define SHOWMAXBUFLEVEL_NO
nixnax	205:c730866cb598	902	#ifdef SHOWMAXBUFLEVEL_YES
nixnax	205:c730866cb598	903	// if this is enabled then the maximum value of the serial port receive buffer will show up in the http headers of your browser - nice for debugging
nixnax	205:c730866cb598	904	n=n+sprintf(n+dataStart,"Maxbuflevel: %d\r\n", ppp.rx.maxbuflevel);
nixnax	205:c730866cb598	905	#endif
nixnax	142:54d1543e23e5	906	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	907	nHeader=n; // size of HTTP header
nixnax	185:4cd8f91e9d49	908
nixnax	142:54d1543e23e5	909	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	910	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	911	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	912	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	185:4cd8f91e9d49	913
nixnax	142:54d1543e23e5	914	} else if ( (httpGet5 == 'w') && (httpGet6 == 's') ) { // "ws" is a special page for websocket demo
nixnax	142:54d1543e23e5	915	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	916	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	185:4cd8f91e9d49	917	*flags = TCP_FLAG_ACK \| TCP_FLAG_PSH; // for a websocket page we do NOT close the connection
nixnax	142:54d1543e23e5	918	} else {
nixnax	142:54d1543e23e5	919	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	920	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	921	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	922	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	923	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	924	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	925	#else
nixnax	142:54d1543e23e5	926	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	167:ff8a2d8beeb1	927	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	928	}
nixnax	142:54d1543e23e5	929	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	930	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	931	#endif
nixnax	142:54d1543e23e5	932	} else {
nixnax	142:54d1543e23e5	933	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	934	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	935	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	936	}
nixnax	142:54d1543e23e5	937	}
nixnax	142:54d1543e23e5	938	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	939	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	940	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	941	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	942	return n; // total byte size of our response
nixnax	142:54d1543e23e5	943	}
nixnax	142:54d1543e23e5	944
nixnax	160:bd701ad564cb	945	/// Handle TCP data that is not an HTTP GET.
nixnax	160:bd701ad564cb	946	/// This is handy when for example you want to use netcat (nc.exe) to talk to PPP-Blinky.
nixnax	160:bd701ad564cb	947	/// This could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	948	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	949	{
nixnax	142:54d1543e23e5	950	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	951	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	160:bd701ad564cb	952	char mask [4];
nixnax	160:bd701ad564cb	953	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	160:bd701ad564cb	954	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	160:bd701ad564cb	955	if((dataStart[1]&0x80)==0x80) // test if the mask bit is set, which means all data is xor'ed with the mask
nixnax	160:bd701ad564cb	956	for (int i=0; i<websocketMessageSize; i++) dataStart[i+6]^= mask[i%4]; // unmask each byte with one of the mask bytes
nixnax	160:bd701ad564cb	957	dataStart[1] = len-2; // add four extra bytes to the message length because we don't use mask bytes for the send
nixnax	160:bd701ad564cb	958	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	160:bd701ad564cb	959	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	960	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	961	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	962	dataStart[1]=0; // we don't have mask bytes on
nixnax	160:bd701ad564cb	963	} else {
nixnax	184:4133f557d4d4	964	if ( len > 1 ) { // we assume a length of 1 is a keep-alive or push packet
nixnax	184:4133f557d4d4	965	if (v1) putsWhileCheckingInput("TCP data received\n"); // all other tcp push packets
nixnax	184:4133f557d4d4	966	}
nixnax	163:d1b4328e9f08	967	}
nixnax	142:54d1543e23e5	968	return n; // total byte size of our response
nixnax	142:54d1543e23e5	969	}
nixnax	142:54d1543e23e5	970
nixnax	173:6774a0c851c4	971	/// dump the TCP data to the debug serial port
nixnax	173:6774a0c851c4	972	void dumpDataTCP(int outGoing)
nixnax	173:6774a0c851c4	973	{
nixnax	173:6774a0c851c4	974	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	173:6774a0c851c4	975	if (v2) {
nixnax	173:6774a0c851c4	976	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	173:6774a0c851c4	977	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	978	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax	173:6774a0c851c4	979	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	980	ppp.tcpData = ppp.tcpStart + headerSizeTcp; // start of tcp data
nixnax	173:6774a0c851c4	981	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	173:6774a0c851c4	982	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	173:6774a0c851c4	983	char pbuf[80]; // local print buffer
nixnax	173:6774a0c851c4	984	int n=0;
nixnax	205:c730866cb598	985
nixnax	173:6774a0c851c4	986	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	205:c730866cb598	987
nixnax	173:6774a0c851c4	988	n=n+sprintf(pbuf+n, "IP:%d ipHeader:%d tcpHeader:%d tcpData:%d\n", packetLengthIp, headerSizeIp, headerSizeTcp, tcpDataSize); // 1 for more verbose
nixnax	184:4133f557d4d4	989	if (n>70) putsWhileCheckingInput("n>pbuf overflow in dumpDataTCP()\n");
nixnax	205:c730866cb598	990
nixnax	173:6774a0c851c4	991	putsWhileCheckingInput( pbuf );
nixnax	173:6774a0c851c4	992	if (tcpDataSize > 0) {
nixnax	173:6774a0c851c4	993	ppp.tcpData[tcpDataSize]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	173:6774a0c851c4	994	putsWhileCheckingInput( ppp.tcpData ); // print the tcp payload data
nixnax	173:6774a0c851c4	995	putsWhileCheckingInput("\n");
nixnax	173:6774a0c851c4	996	}
nixnax	173:6774a0c851c4	997	putsWhileCheckingInput( "\x1b[30m" ); // VT100 color code, print black
nixnax	173:6774a0c851c4	998	}
nixnax	173:6774a0c851c4	999	#endif
nixnax	173:6774a0c851c4	1000	}
nixnax	173:6774a0c851c4	1001
nixnax	142:54d1543e23e5	1002	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1003	/// 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	1004	void tcpHandler()
nixnax	142:54d1543e23e5	1005	{
nixnax	154:18b2bd92f557	1006	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	154:18b2bd92f557	1007	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	1008	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate TCP header start
nixnax	154:18b2bd92f557	1009	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	154:18b2bd92f557	1010	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	1011	char * tcpDataIn = ppp.tcpStart + headerSizeTcp; // start of data TCP data after TCP header
nixnax	154:18b2bd92f557	1012	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	154:18b2bd92f557	1013
nixnax	154:18b2bd92f557	1014	unsigned int seq_in = __REV(ppp.tcp->seqTcpR);
nixnax	154:18b2bd92f557	1015	unsigned int ack_in = __REV(ppp.tcp->ackTcpR);
nixnax	142:54d1543e23e5	1016	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	1017	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	1018
nixnax	142:54d1543e23e5	1019	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	173:6774a0c851c4	1020	headerSizeIp=20;
nixnax	173:6774a0c851c4	1021	ppp.ip->headerLength = headerSizeIp/4; // ip header is 20 bytes long
nixnax	173:6774a0c851c4	1022	ppp.ip->lengthR = __REV(40); // 20 ip header + 20 tcp header
nixnax	173:6774a0c851c4	1023	//tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	154:18b2bd92f557	1024	headerSizeTcp = 20; // shorten outgoing TCP header size 20 bytes
nixnax	173:6774a0c851c4	1025	ppp.tcpStart = ppp.ipStart + headerSizeIp; // recalc TCP header start
nixnax	154:18b2bd92f557	1026	ppp.tcp->offset = (headerSizeTcp/4);
nixnax	173:6774a0c851c4	1027	char * tcpDataOut = ppp.tcpStart + headerSizeTcp; // start of outgoing data
nixnax	142:54d1543e23e5	1028
nixnax	142:54d1543e23e5	1029	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	1030	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	160:bd701ad564cb	1031
nixnax	185:4cd8f91e9d49	1032	ppp.tcp->windowR = __REV16( 1200 ); // set tcp window size to 1200 bytes
nixnax	142:54d1543e23e5	1033
nixnax	142:54d1543e23e5	1034	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	1035
nixnax	156:163c23249731	1036	switch ( ppp.tcp->flag.All ) {
nixnax	142:54d1543e23e5	1037	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1038	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1039	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1040	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1041	break;
nixnax	184:4133f557d4d4	1042	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1043	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	184:4133f557d4d4	1044	if ( (ppp.tcp->flag.All == TCP_FLAG_ACK) && (tcpDataSize == 0)) return; // handle zero-size ack messages by ignoring them
nixnax	142:54d1543e23e5	1045	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	179:ba2b2ddd0da5	1046	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // we have data, set the PSH flag
nixnax	185:4cd8f91e9d49	1047	dataLen = httpResponse(tcpDataOut, &flagsOut); // send an http response
nixnax	142:54d1543e23e5	1048	} else {
nixnax	158:841592aed956	1049	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax	179:ba2b2ddd0da5	1050	if (dataLen > 0) flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // if we have any data set the PSH flag
nixnax	142:54d1543e23e5	1051	}
nixnax	142:54d1543e23e5	1052	break;
nixnax	142:54d1543e23e5	1053	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1054	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1055	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1056	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1057	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1058	break;
nixnax	142:54d1543e23e5	1059	default:
nixnax	179:ba2b2ddd0da5	1060	return; // ignore all other packets
nixnax	142:54d1543e23e5	1061	} // switch
nixnax	142:54d1543e23e5	1062
nixnax	142:54d1543e23e5	1063	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1064	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1065	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1066	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1067
nixnax	158:841592aed956	1068	ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	158:841592aed956	1069	ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	160:bd701ad564cb	1070
nixnax	156:163c23249731	1071	ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1072
nixnax	159:4d1bf96a59cd	1073	// recalculate all the header sizes
nixnax	154:18b2bd92f557	1074	tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax	154:18b2bd92f557	1075	int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax	159:4d1bf96a59cd	1076	ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax	142:54d1543e23e5	1077	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	1078
nixnax	142:54d1543e23e5	1079	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1080	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	170:3d3b2126181c	1081	checkSumPseudoHeader( tcpSize ); // get the TCP pseudo-header checksum
nixnax	159:4d1bf96a59cd	1082	ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	161:d59f778bc8ab	1083	unsigned int pseudoHeaderSum=dataCheckSum(ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax	159:4d1bf96a59cd	1084	ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	160:bd701ad564cb	1085
nixnax	170:3d3b2126181c	1086	dumpHeaderIP(1); // dump outgoing IP header before sending the frame
nixnax	170:3d3b2126181c	1087	dumpHeaderTCP(1); // dump outgoing TCP header before sending the frame
nixnax	173:6774a0c851c4	1088	dumpDataTCP(1); // dump outgoing TCP data before sending the frame
nixnax	182:f039ec218c9f	1089	if (0) wait_ms(45); // 45 ms delay before sending frame - a typical internet delay time
nixnax	144:01d98cf7738e	1090	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1091	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1092	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1093	}
nixnax	142:54d1543e23e5	1094
nixnax	142:54d1543e23e5	1095	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1096	void TCPpacket()
nixnax	142:54d1543e23e5	1097	{
nixnax	173:6774a0c851c4	1098	dumpHeaderIP(0); // dump incoming packet IP header
nixnax	173:6774a0c851c4	1099	dumpHeaderTCP(0); // dump incoming packet TCP header
nixnax	173:6774a0c851c4	1100	dumpDataTCP(0); // dump incoming packet data
nixnax	142:54d1543e23e5	1101	tcpHandler();
nixnax	142:54d1543e23e5	1102	}
nixnax	142:54d1543e23e5	1103
nixnax	142:54d1543e23e5	1104	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1105	void otherProtocol()
nixnax	142:54d1543e23e5	1106	{
nixnax	142:54d1543e23e5	1107	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1108	}
nixnax	142:54d1543e23e5	1109
nixnax	142:54d1543e23e5	1110	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1111	void IPframe()
nixnax	142:54d1543e23e5	1112	{
nixnax	167:ff8a2d8beeb1	1113	int protocol = ppp.ip->protocol;
nixnax	142:54d1543e23e5	1114	switch (protocol) {
nixnax	142:54d1543e23e5	1115	case 1:
nixnax	142:54d1543e23e5	1116	ICMPpacket();
nixnax	142:54d1543e23e5	1117	break;
nixnax	142:54d1543e23e5	1118	case 2:
nixnax	142:54d1543e23e5	1119	IGMPpacket();
nixnax	142:54d1543e23e5	1120	break;
nixnax	142:54d1543e23e5	1121	case 17:
nixnax	142:54d1543e23e5	1122	UDPpacket();
nixnax	142:54d1543e23e5	1123	break;
nixnax	142:54d1543e23e5	1124	case 6:
nixnax	142:54d1543e23e5	1125	TCPpacket();
nixnax	142:54d1543e23e5	1126	break;
nixnax	142:54d1543e23e5	1127	default:
nixnax	142:54d1543e23e5	1128	otherProtocol();
nixnax	142:54d1543e23e5	1129	}
nixnax	142:54d1543e23e5	1130	}
nixnax	142:54d1543e23e5	1131
nixnax	142:54d1543e23e5	1132	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1133	void LCPconfReq()
nixnax	142:54d1543e23e5	1134	{
nixnax	142:54d1543e23e5	1135	debugPrintf("LCP Config ");
nixnax	175:b4e6f8a6fe00	1136	if ( ppp.lcp->lengthR != __REV16(4) ) {
nixnax	175:b4e6f8a6fe00	1137	ppp.lcp->code=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1138	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1139	sendPppFrame();
nixnax	142:54d1543e23e5	1140	} else {
nixnax	175:b4e6f8a6fe00	1141	ppp.lcp->code=2; // ack zero conf
nixnax	142:54d1543e23e5	1142	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1143	sendPppFrame();
nixnax	142:54d1543e23e5	1144	debugPrintf("LCP Ask\n");
nixnax	175:b4e6f8a6fe00	1145	ppp.lcp->code=1; // request no options
nixnax	144:01d98cf7738e	1146	sendPppFrame();
nixnax	142:54d1543e23e5	1147	}
nixnax	142:54d1543e23e5	1148	}
nixnax	142:54d1543e23e5	1149
nixnax	142:54d1543e23e5	1150	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1151	void LCPconfAck()
nixnax	142:54d1543e23e5	1152	{
nixnax	142:54d1543e23e5	1153	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1154	}
nixnax	142:54d1543e23e5	1155
nixnax	143:c5019f856a56	1156	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1157	void LCPend()
nixnax	142:54d1543e23e5	1158	{
nixnax	175:b4e6f8a6fe00	1159	ppp.lcp->code=6; // end
nixnax	144:01d98cf7738e	1160	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1161	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1162	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1163	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1164	}
nixnax	142:54d1543e23e5	1165
nixnax	142:54d1543e23e5	1166	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1167	void LCPother()
nixnax	142:54d1543e23e5	1168	{
nixnax	142:54d1543e23e5	1169	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1170	dumpPPPFrame();
nixnax	142:54d1543e23e5	1171	}
nixnax	142:54d1543e23e5	1172
nixnax	142:54d1543e23e5	1173	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1174	void LCPframe()
nixnax	142:54d1543e23e5	1175	{
nixnax	175:b4e6f8a6fe00	1176	int code = ppp.lcp->code;
nixnax	142:54d1543e23e5	1177	switch (code) {
nixnax	142:54d1543e23e5	1178	case 1:
nixnax	142:54d1543e23e5	1179	LCPconfReq();
nixnax	142:54d1543e23e5	1180	break; // config request
nixnax	142:54d1543e23e5	1181	case 2:
nixnax	142:54d1543e23e5	1182	LCPconfAck();
nixnax	142:54d1543e23e5	1183	break; // config ack
nixnax	142:54d1543e23e5	1184	case 5:
nixnax	142:54d1543e23e5	1185	LCPend();
nixnax	142:54d1543e23e5	1186	break; // end connection
nixnax	142:54d1543e23e5	1187	default:
nixnax	142:54d1543e23e5	1188	LCPother();
nixnax	142:54d1543e23e5	1189	}
nixnax	142:54d1543e23e5	1190	}
nixnax	142:54d1543e23e5	1191
nixnax	142:54d1543e23e5	1192	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1193	void discardedFrame()
nixnax	142:54d1543e23e5	1194	{
nixnax	142:54d1543e23e5	1195	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	1196	}
nixnax	142:54d1543e23e5	1197
nixnax	142:54d1543e23e5	1198	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1199	void determinePacketType()
nixnax	142:54d1543e23e5	1200	{
nixnax	167:ff8a2d8beeb1	1201	if ( ppp.ppp->address != 0xff ) {
nixnax	167:ff8a2d8beeb1	1202	debugPrintf("Unexpected: PPP address != ff\n");
nixnax	142:54d1543e23e5	1203	return;
nixnax	142:54d1543e23e5	1204	}
nixnax	167:ff8a2d8beeb1	1205	if ( ppp.ppp->control != 3 ) {
nixnax	167:ff8a2d8beeb1	1206	debugPrintf("Unexpected: PPP control != 3\n");
nixnax	142:54d1543e23e5	1207	return;
nixnax	142:54d1543e23e5	1208	}
nixnax	167:ff8a2d8beeb1	1209	unsigned int protocol = __REV16( ppp.ppp->protocolR );
nixnax	167:ff8a2d8beeb1	1210	switch ( protocol ) {
nixnax	167:ff8a2d8beeb1	1211	case 0xc021:
nixnax	142:54d1543e23e5	1212	LCPframe();
nixnax	142:54d1543e23e5	1213	break; // link control
nixnax	167:ff8a2d8beeb1	1214	case 0x8021:
nixnax	142:54d1543e23e5	1215	IPCPframe();
nixnax	142:54d1543e23e5	1216	break; // IP control
nixnax	167:ff8a2d8beeb1	1217	case 0x0021:
nixnax	142:54d1543e23e5	1218	IPframe();
nixnax	142:54d1543e23e5	1219	break; // IP itself
nixnax	142:54d1543e23e5	1220	default:
nixnax	142:54d1543e23e5	1221	discardedFrame();
nixnax	142:54d1543e23e5	1222	}
nixnax	142:54d1543e23e5	1223	}
nixnax	142:54d1543e23e5	1224
nixnax	146:a45f49a2b29c	1225	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1226	void sniff()
nixnax	146:a45f49a2b29c	1227	{
nixnax	146:a45f49a2b29c	1228	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	1229	}
nixnax	146:a45f49a2b29c	1230
nixnax	142:54d1543e23e5	1231	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1232	void waitForPppFrame()
nixnax	142:54d1543e23e5	1233	{
nixnax	142:54d1543e23e5	1234	while(1) {
nixnax	182:f039ec218c9f	1235	sendUdpData(); // handle received characters from the DEBUG TERMINAL
nixnax	142:54d1543e23e5	1236	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1237	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1238	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1239	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1240	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1241	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1242	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	181:bcfe7fe2142d	1243	ppp.firstFrame=0; // clear first frame flag
nixnax	142:54d1543e23e5	1244	} else {
nixnax	142:54d1543e23e5	1245	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1246	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1247	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1248	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1249	break;
nixnax	142:54d1543e23e5	1250	}
nixnax	142:54d1543e23e5	1251	}
nixnax	142:54d1543e23e5	1252	}
nixnax	142:54d1543e23e5	1253	}
nixnax	142:54d1543e23e5	1254	}
nixnax	142:54d1543e23e5	1255
nixnax	205:c730866cb598	1256	/// Wait for a dial-up modem connect command ("CLIENT") from the host PC, if found, we set ppp.online to true, which starts the IP packet scanner.
nixnax	205:c730866cb598	1257	// Note: a 0x7E in the input stream (ppp start of frame character) will also set ppp.online to true - see the code in pppReceiveHandler()
nixnax	153:7993def8663f	1258	void waitForPcConnectString()
nixnax	142:54d1543e23e5	1259	{
nixnax	142:54d1543e23e5	1260	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1261	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1262	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1263	if (found1 != NULL) {
nixnax	205:c730866cb598	1264	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	142:54d1543e23e5	1265	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	142:54d1543e23e5	1266	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1267	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1268	}
nixnax	142:54d1543e23e5	1269	}
nixnax	142:54d1543e23e5	1270	}
nixnax	142:54d1543e23e5	1271
nixnax	144:01d98cf7738e	1272	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1273	void initializePpp()
nixnax	142:54d1543e23e5	1274	{
nixnax	144:01d98cf7738e	1275	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	184:4133f557d4d4	1276	debugPrintf("\x1b[2J\x1b[H\x1b[30m");
nixnax	184:4133f557d4d4	1277	wait_ms(200); // a brief wait so a human can see the reset event
nixnax	184:4133f557d4d4	1278	debugPrintf("mbed PPP-Blinky HTTP & WebSocket server ready :)\n"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax	184:4133f557d4d4	1279
nixnax	179:ba2b2ddd0da5	1280	pppInitStruct(); // initialize all the variables/properties/buffers
nixnax	179:ba2b2ddd0da5	1281	pc.baud(115200); // pc serial port acting as a dial-up modem - for PPP traffic
nixnax	179:ba2b2ddd0da5	1282	pc.attach(&pppReceiveHandler, RawSerial::RxIrq); // set up serial port receive interrupt handler
nixnax	143:c5019f856a56	1283	}

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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.