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@221:1d7c32d8256b, 2018-08-25 (annotated)

Committer:: nixnax
Date:: Sat Aug 25 17:11:39 2018 +0000
Revision:: 221:1d7c32d8256b
Parent:: 220:54f45f924707
Child:: 222:0ec93b1ff979

Removed putcwhilechecking and putswhilechecking.; Added ppp.xx.bufferfull

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	207:28cd834b785d	40
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	221:1d7c32d8256b	74	#define debugPuts(x...) xx.puts(x)
nixnax	142:54d1543e23e5	75	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	76	#else
nixnax	142:54d1543e23e5	77	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	78	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	79	#define debugPutc(x...) {}
nixnax	221:1d7c32d8256b	80	#define debugPuts(x...) {}
nixnax	142:54d1543e23e5	81	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	82	#endif
nixnax	142:54d1543e23e5	83
nixnax	142:54d1543e23e5	84	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	182:f039ec218c9f	85	#define v0 1
nixnax	142:54d1543e23e5	86	#define v1 0
nixnax	142:54d1543e23e5	87	#define v2 0
nixnax	182:f039ec218c9f	88	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	182:f039ec218c9f	89	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	90
nixnax	142:54d1543e23e5	91	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	92	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	93
nixnax	142:54d1543e23e5	94	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	95	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	96	<html>\
nixnax	142:54d1543e23e5	97	<head>\
nixnax	146:a45f49a2b29c	98	<title>mbed PPP-Blinky</title>\r\n\
nixnax	142:54d1543e23e5	99	</head>\
nixnax	142:54d1543e23e5	100	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	101	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	102	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	210:a2a651249a9a	103	<h1><a href=\"/w\">WebSocket Test</a></h1>\
nixnax	142:54d1543e23e5	104	<h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	105	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	219:cbf6a235d1f2	106	<h1><a href=\"http://jsfiddle.net/d26cyuh2/21\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	107	</body>\
nixnax	210:a2a651249a9a	108	</html>\r\n"; // size = 451 bytes + 1 null byte = 452 bytes
nixnax	142:54d1543e23e5	109
nixnax	167:ff8a2d8beeb1	110	// this is a websocket demo html page we serve when GET /ws is requested
nixnax	142:54d1543e23e5	111	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	112	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	113	<html>\
nixnax	142:54d1543e23e5	114	<head>\
nixnax	142:54d1543e23e5	115	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	116	<script>\
nixnax	142:54d1543e23e5	117	window.onload=function(){\
nixnax	142:54d1543e23e5	118	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	119	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	120	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	121	var ctr=0;\
nixnax	142:54d1543e23e5	122	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	123	btn.onclick=function(){\
nixnax	142:54d1543e23e5	124	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	125	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	126	x.onopen=function(){\
nixnax	142:54d1543e23e5	127	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	128	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	129	};\
nixnax	142:54d1543e23e5	130	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	131	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	132	} else {\
nixnax	142:54d1543e23e5	133	x.send(ctr);\
nixnax	142:54d1543e23e5	134	ctr=ctr+1;\
nixnax	142:54d1543e23e5	135	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	136	}\
nixnax	142:54d1543e23e5	137	};\
nixnax	142:54d1543e23e5	138	};\
nixnax	142:54d1543e23e5	139	</script>\
nixnax	142:54d1543e23e5	140	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	141	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	142	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	143	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	144	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	145	</body>\
nixnax	142:54d1543e23e5	146	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	147
nixnax	142:54d1543e23e5	148	// 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	149	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	150	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	151	// See instructions at the top.
nixnax	142:54d1543e23e5	152	// 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	153	RawSerial pc (USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	154
nixnax	142:54d1543e23e5	155	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	156
nixnax	142:54d1543e23e5	157	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	158	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	159
nixnax	142:54d1543e23e5	160	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	161
nixnax	142:54d1543e23e5	162	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	163	void pppInitStruct()
nixnax	142:54d1543e23e5	164	{
nixnax	209:aa514cd631ee	165	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	166	ppp.online=0;
nixnax	142:54d1543e23e5	167	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	168	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	169	ppp.rx.head=0;
nixnax	142:54d1543e23e5	170	ppp.rx.buflevel=0;
nixnax	209:aa514cd631ee	171	ppp.rx.maxbuflevel=0;
nixnax	221:1d7c32d8256b	172	ppp.rx.bufferfull=0;
nixnax	142:54d1543e23e5	173	ppp.pkt.len=0;
nixnax	154:18b2bd92f557	174	ppp.ipData.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	175	ppp.ledState=0;
nixnax	142:54d1543e23e5	176	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	177	ppp.responseCounter=0;
nixnax	142:54d1543e23e5	178	ppp.firstFrame=1;
nixnax	175:b4e6f8a6fe00	179	ppp.ppp = (pppHeaderType *)ppp.pkt.buf; // pointer to ppp header
nixnax	175:b4e6f8a6fe00	180	ppp.ip = (ipHeaderType *)(ppp.pkt.buf+4); // pointer to IP header
nixnax	142:54d1543e23e5	181	}
nixnax	142:54d1543e23e5	182
nixnax	142:54d1543e23e5	183	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	184	void led1Toggle()
nixnax	142:54d1543e23e5	185	{
nixnax	142:54d1543e23e5	186	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	187	ppp.ledState++;
nixnax	142:54d1543e23e5	188	}
nixnax	142:54d1543e23e5	189
nixnax	179:ba2b2ddd0da5	190	/// Returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax	150:3366bf3d294e	191	int connectedPpp()
nixnax	142:54d1543e23e5	192	{
nixnax	142:54d1543e23e5	193	return ppp.online;
nixnax	143:c5019f856a56	194	}
nixnax	142:54d1543e23e5	195
nixnax	179:ba2b2ddd0da5	196	/// PPP serial port receive interrupt handler.
nixnax	143:c5019f856a56	197	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	198	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	179:ba2b2ddd0da5	199	void pppReceiveHandler()
nixnax	142:54d1543e23e5	200	{
nixnax	142:54d1543e23e5	201	char ch;
nixnax	179:ba2b2ddd0da5	202	while ( pc.readable() ) {
nixnax	216:e3c5a5b47295	203	int hd = (ppp.rx.head+1);
nixnax	221:1d7c32d8256b	204	if (hd > RXBUFLEN) hd=0; // increment and wrap head index
nixnax	142:54d1543e23e5	205	if ( hd == ppp.rx.rtail ) {
nixnax	221:1d7c32d8256b	206	ppp.rx.bufferfull = 1; // set flag if rx buffer is full
nixnax	221:1d7c32d8256b	207	return; // don't read if rx buffer is full
nixnax	142:54d1543e23e5	208	}
nixnax	142:54d1543e23e5	209	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	210	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	209:aa514cd631ee	211	if (ch == 0x7E) { // check for ppp frame start character
nixnax	209:aa514cd631ee	212	if ( ppp.online == 0 ) { // check if we are offline
nixnax	209:aa514cd631ee	213	ppp.online = 1; // if we see a frame start character we immediately change status to online
nixnax	142:54d1543e23e5	214	}
nixnax	142:54d1543e23e5	215	}
nixnax	142:54d1543e23e5	216	ppp.rx.head = hd; // update head pointer
nixnax	221:1d7c32d8256b	217	ppp.rx.buflevel++; // update buffer level counter
nixnax	209:aa514cd631ee	218	if ( ppp.rx.buflevel > ppp.rx.maxbuflevel ) {
nixnax	221:1d7c32d8256b	219	ppp.rx.maxbuflevel = ppp.rx.buflevel; // remember the maximum usage of rx buffer
nixnax	209:aa514cd631ee	220	}
nixnax	142:54d1543e23e5	221	}
nixnax	142:54d1543e23e5	222	}
nixnax	142:54d1543e23e5	223
nixnax	145:098b6ed2f7f2	224	/// Initialize the PPP FCS (frame check sequence) total
nixnax	145:098b6ed2f7f2	225	void fcsReset()
nixnax	142:54d1543e23e5	226	{
nixnax	145:098b6ed2f7f2	227	ppp.fcs=0xffff; // crc restart
nixnax	142:54d1543e23e5	228	}
nixnax	142:54d1543e23e5	229
nixnax	145:098b6ed2f7f2	230	/// update the cumulative PPP FCS (frame check sequence)
nixnax	145:098b6ed2f7f2	231	void fcsDo(int x)
nixnax	142:54d1543e23e5	232	{
nixnax	220:54f45f924707	233	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	234	x>>=1;
nixnax	220:54f45f924707	235	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	236	x>>=1;
nixnax	220:54f45f924707	237	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	238	x>>=1;
nixnax	220:54f45f924707	239	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	240	x>>=1;
nixnax	220:54f45f924707	241	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	242	x>>=1;
nixnax	220:54f45f924707	243	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	244	x>>=1;
nixnax	220:54f45f924707	245	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	246	x>>=1;
nixnax	220:54f45f924707	247	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	248	x>>=1;
nixnax	142:54d1543e23e5	249	}
nixnax	142:54d1543e23e5	250
nixnax	145:098b6ed2f7f2	251	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	252	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	253	{
nixnax	145:098b6ed2f7f2	254	fcsReset();
nixnax	145:098b6ed2f7f2	255	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	256	return ppp.fcs;
nixnax	142:54d1543e23e5	257	}
nixnax	142:54d1543e23e5	258
nixnax	142:54d1543e23e5	259	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	260	int pc_getBuf()
nixnax	142:54d1543e23e5	261	{
nixnax	142:54d1543e23e5	262	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	216:e3c5a5b47295	263	ppp.rx.tail=ppp.rx.tail+1;
nixnax	216:e3c5a5b47295	264	if (ppp.rx.tail > RXBUFLEN) ppp.rx.tail=0;
nixnax	142:54d1543e23e5	265	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	266	return x;
nixnax	142:54d1543e23e5	267	}
nixnax	142:54d1543e23e5	268
nixnax	142:54d1543e23e5	269	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	270	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	271	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	164:c3de3d212c4b	272	/// In WireShark, use "Import Hex File". Import options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	273	void dumpPPPFrame()
nixnax	142:54d1543e23e5	274	{
nixnax	142:54d1543e23e5	275	char pbuf[30];
nixnax	142:54d1543e23e5	276	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	210:a2a651249a9a	277
nixnax	142:54d1543e23e5	278	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	210:a2a651249a9a	279
nixnax	221:1d7c32d8256b	280	debugPuts(pbuf);
nixnax	142:54d1543e23e5	281	}
nixnax	210:a2a651249a9a	282
nixnax	142:54d1543e23e5	283	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	210:a2a651249a9a	284
nixnax	221:1d7c32d8256b	285	debugPuts(pbuf);
nixnax	142:54d1543e23e5	286	}
nixnax	142:54d1543e23e5	287
nixnax	142:54d1543e23e5	288	/// Process a received PPP frame
nixnax	142:54d1543e23e5	289	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	290	{
nixnax	142:54d1543e23e5	291	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	292	if(start==end) {
nixnax	142:54d1543e23e5	293	return; // empty frame
nixnax	142:54d1543e23e5	294	}
nixnax	145:098b6ed2f7f2	295	fcsReset();
nixnax	142:54d1543e23e5	296	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	297	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	298	int unstuff=0;
nixnax	142:54d1543e23e5	299	int idx = start;
nixnax	142:54d1543e23e5	300	while(1) {
nixnax	210:a2a651249a9a	301
nixnax	142:54d1543e23e5	302	if (unstuff==0) {
nixnax	142:54d1543e23e5	303	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	304	else {
nixnax	142:54d1543e23e5	305	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	306	ppp.pkt.len++;
nixnax	142:54d1543e23e5	307	dest++;
nixnax	145:098b6ed2f7f2	308	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	309	}
nixnax	142:54d1543e23e5	310	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	311	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	312	ppp.pkt.len++;
nixnax	142:54d1543e23e5	313	dest++;
nixnax	145:098b6ed2f7f2	314	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	315	unstuff=0;
nixnax	142:54d1543e23e5	316	}
nixnax	216:e3c5a5b47295	317	idx = idx+1;
nixnax	216:e3c5a5b47295	318	if (idx > RXBUFLEN) idx=0;
nixnax	142:54d1543e23e5	319	if (idx == end) break;
nixnax	142:54d1543e23e5	320	}
nixnax	145:098b6ed2f7f2	321	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	322	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	323	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	324	determinePacketType();
nixnax	142:54d1543e23e5	325	} else {
nixnax	142:54d1543e23e5	326	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	327	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	328	char pbuf[50]; // local print buffer
nixnax	210:a2a651249a9a	329
nixnax	142:54d1543e23e5	330	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	210:a2a651249a9a	331
nixnax	221:1d7c32d8256b	332	debugPuts( pbuf );
nixnax	142:54d1543e23e5	333	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	334	#endif
nixnax	142:54d1543e23e5	335	}
nixnax	142:54d1543e23e5	336	}
nixnax	142:54d1543e23e5	337
nixnax	142:54d1543e23e5	338	/// output a character to the PPP port while checking for incoming characters
nixnax	221:1d7c32d8256b	339	void pcdebugPutc(int ch)
nixnax	142:54d1543e23e5	340	{
nixnax	210:a2a651249a9a	341
nixnax	142:54d1543e23e5	342	pc.putc(ch);
nixnax	210:a2a651249a9a	343
nixnax	142:54d1543e23e5	344	}
nixnax	142:54d1543e23e5	345
nixnax	142:54d1543e23e5	346	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	347	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	348	{
nixnax	142:54d1543e23e5	349	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	221:1d7c32d8256b	350	pcdebugPutc(0x7d);
nixnax	221:1d7c32d8256b	351	pcdebugPutc(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	352	} else {
nixnax	221:1d7c32d8256b	353	pcdebugPutc(ch);
nixnax	142:54d1543e23e5	354	}
nixnax	142:54d1543e23e5	355	}
nixnax	142:54d1543e23e5	356
nixnax	142:54d1543e23e5	357	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	358	void sendPppFrame()
nixnax	143:c5019f856a56	359	{
nixnax	172:449dd7a28955	360	ppp.responseCounter++; // count the number of ppp frames we send
nixnax	145:098b6ed2f7f2	361	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	362	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	363	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	221:1d7c32d8256b	364	pcdebugPutc(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	365	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	366	wait_us(86); // wait one character time
nixnax	210:a2a651249a9a	367
nixnax	142:54d1543e23e5	368	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	369	}
nixnax	221:1d7c32d8256b	370	pcdebugPutc(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	371	}
nixnax	142:54d1543e23e5	372
nixnax	143:c5019f856a56	373	/// 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	374	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	375	{
nixnax	143:c5019f856a56	376	int result=0;
nixnax	143:c5019f856a56	377	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	378	return result;
nixnax	143:c5019f856a56	379	}
nixnax	143:c5019f856a56	380
nixnax	177:dab9e685af53	381	/// convert 4-byte ip address to 32-bit
nixnax	179:ba2b2ddd0da5	382	unsigned int ip( int a, int b, int c, int d)
nixnax	179:ba2b2ddd0da5	383	{
nixnax	177:dab9e685af53	384	return a<<24 \| b<<16 \| c<<8 \| d;
nixnax	177:dab9e685af53	385	}
nixnax	177:dab9e685af53	386
nixnax	142:54d1543e23e5	387	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	388	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	389	{
nixnax	142:54d1543e23e5	390	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	173:6774a0c851c4	391	if(ppp.ipcp->request[0]==3) {
nixnax	143:c5019f856a56	392	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	173:6774a0c851c4	393	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	394	}
nixnax	143:c5019f856a56	395
nixnax	167:ff8a2d8beeb1	396	ppp.ipcp->code=2; // change code to ack
nixnax	144:01d98cf7738e	397	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	398
nixnax	142:54d1543e23e5	399	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	167:ff8a2d8beeb1	400	ppp.ipcp->code=1; // change code to request
nixnax	167:ff8a2d8beeb1	401	ppp.ipcp->lengthR = __REV16( 4 ); // 4 is minimum length - no options in this request
nixnax	167:ff8a2d8beeb1	402	ppp.pkt.len=4+4+2; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	403	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	404	}
nixnax	142:54d1543e23e5	405
nixnax	142:54d1543e23e5	406	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	407	void ipcpAckHandler()
nixnax	142:54d1543e23e5	408	{
nixnax	142:54d1543e23e5	409	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	410	}
nixnax	142:54d1543e23e5	411
nixnax	143:c5019f856a56	412	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	413	/// 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	414	void ipcpNackHandler()
nixnax	142:54d1543e23e5	415	{
nixnax	146:a45f49a2b29c	416	debugPrintf("Their IPCP Nack\n");
nixnax	173:6774a0c851c4	417	if (ppp.ipcp->request[0]==3) { // check if the NACK contains an IP address parameter
nixnax	167:ff8a2d8beeb1	418	ppp.ipcp->code=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	419	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	420	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	421	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	422	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	423	}
nixnax	142:54d1543e23e5	424	}
nixnax	142:54d1543e23e5	425
nixnax	142:54d1543e23e5	426	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	427	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	428	{
nixnax	142:54d1543e23e5	429	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	430	}
nixnax	142:54d1543e23e5	431
nixnax	142:54d1543e23e5	432	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	433	void IPCPframe()
nixnax	142:54d1543e23e5	434	{
nixnax	167:ff8a2d8beeb1	435	int action = ppp.ipcp->code; // packet type is here
nixnax	167:ff8a2d8beeb1	436	switch (action) {
nixnax	142:54d1543e23e5	437	case 1:
nixnax	142:54d1543e23e5	438	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	439	break;
nixnax	142:54d1543e23e5	440	case 2:
nixnax	142:54d1543e23e5	441	ipcpAckHandler();
nixnax	142:54d1543e23e5	442	break;
nixnax	142:54d1543e23e5	443	case 3:
nixnax	142:54d1543e23e5	444	ipcpNackHandler();
nixnax	142:54d1543e23e5	445	break;
nixnax	142:54d1543e23e5	446	default:
nixnax	142:54d1543e23e5	447	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	448	}
nixnax	142:54d1543e23e5	449	}
nixnax	142:54d1543e23e5	450
nixnax	142:54d1543e23e5	451	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	161:d59f778bc8ab	452	unsigned int dataCheckSum(char * ptr, int len, int restart)
nixnax	142:54d1543e23e5	453	{
nixnax	159:4d1bf96a59cd	454	unsigned int i,hi,lo;
nixnax	142:54d1543e23e5	455	unsigned char placeHolder;
nixnax	161:d59f778bc8ab	456	if (restart) ppp.sum=0;
nixnax	142:54d1543e23e5	457	if (len&1) {
nixnax	142:54d1543e23e5	458	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	459	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	460	}
nixnax	142:54d1543e23e5	461	i=0;
nixnax	142:54d1543e23e5	462	while ( i<len ) {
nixnax	210:a2a651249a9a	463
nixnax	142:54d1543e23e5	464	hi = ptr[i++];
nixnax	142:54d1543e23e5	465	lo = ptr[i++];
nixnax	159:4d1bf96a59cd	466	ppp.sum = ppp.sum + ((hi<<8)\|lo);
nixnax	142:54d1543e23e5	467	}
nixnax	142:54d1543e23e5	468	if (len&1) {
nixnax	142:54d1543e23e5	469	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	470	}
nixnax	159:4d1bf96a59cd	471	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax	159:4d1bf96a59cd	472	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax	159:4d1bf96a59cd	473	return ~ppp.sum;
nixnax	142:54d1543e23e5	474	}
nixnax	142:54d1543e23e5	475
nixnax	142:54d1543e23e5	476	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	477	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	478	{
nixnax	161:d59f778bc8ab	479	ppp.ip->checksumR=0; // zero the checsum in the IP header
nixnax	161:d59f778bc8ab	480	int len = 4 * ppp.ip->headerLength; // length of IP header in bytes
nixnax	161:d59f778bc8ab	481	unsigned int sum = dataCheckSum(ppp.ipStart,len,1);
nixnax	161:d59f778bc8ab	482	ppp.ip->checksumR = __REV16( sum ); // insert fresh checksum
nixnax	146:a45f49a2b29c	483	}
nixnax	146:a45f49a2b29c	484
nixnax	147:0f40005cbc5f	485	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	486	void swapIpAddresses()
nixnax	147:0f40005cbc5f	487	{
nixnax	162:594729c0e5c1	488	unsigned int tempHold;
nixnax	162:594729c0e5c1	489	tempHold = ppp.ip->srcAdrR; // tempHold <- source IP
nixnax	162:594729c0e5c1	490	ppp.ip->srcAdrR = ppp.ip->dstAdrR; // source <- dest
nixnax	162:594729c0e5c1	491	ppp.ip->dstAdrR = tempHold; // dest <- tempHold*/
nixnax	147:0f40005cbc5f	492	}
nixnax	147:0f40005cbc5f	493
nixnax	149:969d98f6fb88	494	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	495	void swapIpPorts()
nixnax	149:969d98f6fb88	496	{
nixnax	173:6774a0c851c4	497	int headerSizeIP = 4 * (ppp.ip->headerLength); // calculate size of IP header
nixnax	173:6774a0c851c4	498	char * ipSrcPort = ppp.ipStart + headerSizeIP + 0; // ip source port location
nixnax	173:6774a0c851c4	499	char * ipDstPort = ppp.ipStart + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	500	char tempHold[2];
nixnax	149:969d98f6fb88	501	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	502	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	503	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	504	}
nixnax	149:969d98f6fb88	505
nixnax	170:3d3b2126181c	506	/// Build the "pseudo header" required for UDP and TCP, then calculate its checksum
nixnax	170:3d3b2126181c	507	void checkSumPseudoHeader( unsigned int packetLength )
nixnax	170:3d3b2126181c	508	{
nixnax	170:3d3b2126181c	509	// 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	510	pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax	170:3d3b2126181c	511	pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax	170:3d3b2126181c	512	pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax	170:3d3b2126181c	513	pseudoHeader.zero = 0; // zero byte
nixnax	170:3d3b2126181c	514	pseudoHeader.protocol = ppp.ip->protocol; // protocol number (udp or tcp)
nixnax	170:3d3b2126181c	515	pseudoHeader.lengthR = __REV16( packetLength ); // size of tcp or udp packet
nixnax	170:3d3b2126181c	516	dataCheckSum(pseudoHeader.start, 12, 1); // calculate this header's checksum
nixnax	170:3d3b2126181c	517	}
nixnax	170:3d3b2126181c	518
nixnax	171:46b36d4edd1d	519	/// initialize an IP packet to send
nixnax	171:46b36d4edd1d	520	void initIP (unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, unsigned int protocol)
nixnax	171:46b36d4edd1d	521	{
nixnax	171:46b36d4edd1d	522	ppp.ppp->address = 0xff;
nixnax	171:46b36d4edd1d	523	ppp.ppp->control = 3;
nixnax	171:46b36d4edd1d	524	ppp.ppp->protocolR = __REV16( 0x0021 );
nixnax	171:46b36d4edd1d	525	ppp.ip->version = 4;
nixnax	171:46b36d4edd1d	526	ppp.ip->headerLength = 5; // 5 words = 20 bytes
nixnax	171:46b36d4edd1d	527	ppp.ip->identR = __REV16(ppp.ipData.ident++); // insert our ident
nixnax	171:46b36d4edd1d	528	ppp.ip->dontFragment=1;
nixnax	171:46b36d4edd1d	529	ppp.ip->ttl=128;
nixnax	171:46b36d4edd1d	530	ppp.ip->protocol = protocol; // udp
nixnax	171:46b36d4edd1d	531	ppp.ip->srcAdrR = __REV(srcIp);
nixnax	171:46b36d4edd1d	532	ppp.ip->dstAdrR = __REV(dstIp);
nixnax	171:46b36d4edd1d	533	ppp.udpStart = ppp.ipStart + 20; // calculate start of udp header
nixnax	171:46b36d4edd1d	534	ppp.udp->srcPortR = __REV16(srcPort); // source port
nixnax	171:46b36d4edd1d	535	ppp.udp->dstPortR = __REV16(dstPort); // dest port
nixnax	171:46b36d4edd1d	536	}
nixnax	171:46b36d4edd1d	537
nixnax	171:46b36d4edd1d	538
nixnax	171:46b36d4edd1d	539	/// Build a UDP packet from scratch
nixnax	171:46b36d4edd1d	540	void sendUdp(unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, char * message,int msgLen)
nixnax	171:46b36d4edd1d	541	{
nixnax	171:46b36d4edd1d	542	struct {
nixnax	171:46b36d4edd1d	543	unsigned int ipAll; // length of entire ip packet
nixnax	171:46b36d4edd1d	544	unsigned int ipHeader; // length of ip header
nixnax	171:46b36d4edd1d	545	unsigned int udpAll; // length of entire udp packet
nixnax	171:46b36d4edd1d	546	unsigned int udpData; // length of udp data segment
nixnax	171:46b36d4edd1d	547	} len;
nixnax	171:46b36d4edd1d	548	len.ipHeader = 20; // ip header length
nixnax	171:46b36d4edd1d	549	len.udpData = msgLen; // udp data size
nixnax	171:46b36d4edd1d	550	len.udpAll = len.udpData+8; // update local udp packet length
nixnax	171:46b36d4edd1d	551	len.ipAll = len.ipHeader + len.udpAll; // update IP Length
nixnax	171:46b36d4edd1d	552	initIP(srcIp, dstIp, srcPort, dstPort, 17); // init a UDP packet
nixnax	171:46b36d4edd1d	553	ppp.ip->lengthR = __REV16(len.ipAll); // update IP length in buffer
nixnax	171:46b36d4edd1d	554	ppp.udpStart = ppp.ipStart + len.ipHeader; // calculate start of udp header
nixnax	171:46b36d4edd1d	555	memcpy( ppp.udp->data, message, len.udpData ); // copy the message to the buffer
nixnax	171:46b36d4edd1d	556	ppp.udp->lengthR = __REV16(len.udpAll); // update UDP length in buffer
nixnax	171:46b36d4edd1d	557	ppp.pkt.len = len.ipAll+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	558	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	559	checkSumPseudoHeader( len.udpAll ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	560	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	561	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,len.udpAll, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	562	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	563	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	564	}
nixnax	171:46b36d4edd1d	565
nixnax	146:a45f49a2b29c	566	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	567	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	568	void UDPpacket()
nixnax	146:a45f49a2b29c	569	{
nixnax	163:d1b4328e9f08	570	struct {
nixnax	163:d1b4328e9f08	571	unsigned int all; // length of entire ip packet
nixnax	163:d1b4328e9f08	572	unsigned int header; // length of ip header
nixnax	163:d1b4328e9f08	573	} ipLength;
nixnax	163:d1b4328e9f08	574
nixnax	163:d1b4328e9f08	575	struct {
nixnax	165:c47826d07e0d	576	unsigned int all; // length of entire udp packet
nixnax	163:d1b4328e9f08	577	unsigned int data; // length of udp data segment
nixnax	163:d1b4328e9f08	578	} udpLength;
nixnax	163:d1b4328e9f08	579
nixnax	163:d1b4328e9f08	580	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	163:d1b4328e9f08	581	ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	171:46b36d4edd1d	582	udpLength.all = __REV16( ppp.udp->lengthR ); // size of udp packet
nixnax	163:d1b4328e9f08	583	udpLength.data = udpLength.all - 8; // size of udp data
nixnax	147:0f40005cbc5f	584
nixnax	146:a45f49a2b29c	585	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	171:46b36d4edd1d	586	char * srcIP = ppp.ip->srcAdrPtr; // IP source
nixnax	171:46b36d4edd1d	587	char * dstIP = ppp.ip->dstAdrPtr; //IP destination
nixnax	163:d1b4328e9f08	588
nixnax	171:46b36d4edd1d	589	unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); // integer of UDP source port
nixnax	171:46b36d4edd1d	590	unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); // integer of UDP dest port
nixnax	163:d1b4328e9f08	591
nixnax	163:d1b4328e9f08	592	if(v0) {
nixnax	163:d1b4328e9f08	593	debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
nixnax	163:d1b4328e9f08	594	debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
nixnax	163:d1b4328e9f08	595	debugPrintf("Len %03d", udpLength);
nixnax	163:d1b4328e9f08	596	}
nixnax	146:a45f49a2b29c	597	if (v1) {
nixnax	163:d1b4328e9f08	598	int printSize = udpLength.data;
nixnax	146:a45f49a2b29c	599	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	600	for (int i=0; i<printSize; i++) {
nixnax	163:d1b4328e9f08	601	char ch = ppp.udp->data[i];
nixnax	146:a45f49a2b29c	602	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	603	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	604	} else {
nixnax	146:a45f49a2b29c	605	debugPrintf("_");
nixnax	146:a45f49a2b29c	606	}
nixnax	146:a45f49a2b29c	607	}
nixnax	146:a45f49a2b29c	608	}
nixnax	146:a45f49a2b29c	609	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	610	#endif
nixnax	163:d1b4328e9f08	611	int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
nixnax	163:d1b4328e9f08	612	int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	613	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	146:a45f49a2b29c	614	if (echoFound) {
nixnax	171:46b36d4edd1d	615	swapIpAddresses(); // swap IP source and destination
nixnax	171:46b36d4edd1d	616	swapIpPorts(); // swap IP source and destination ports
nixnax	163:d1b4328e9f08	617	memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	170:3d3b2126181c	618	int n=0;
nixnax	170:3d3b2126181c	619	n=n+sprintf(n+ppp.udp->data+udpLength.data, "} UDP Server: PPP-Blinky\n"); // an appendix
nixnax	168:c77eb908042a	620	udpLength.data = udpLength.data + n; // update udp data size with the size of the appendix
nixnax	171:46b36d4edd1d	621	// we may have changed data length, update all the lengths
nixnax	171:46b36d4edd1d	622	udpLength.all = udpLength.data+8; // update local udp packet length
nixnax	171:46b36d4edd1d	623	ipLength.all = ipLength.header + udpLength.all; // update IP Length
nixnax	171:46b36d4edd1d	624	ppp.ip->lengthR = __REV16(ipLength.all); // update IP length in buffer
nixnax	171:46b36d4edd1d	625	ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
nixnax	171:46b36d4edd1d	626	ppp.pkt.len = ipLength.all+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	627	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	628	checkSumPseudoHeader( udpLength.all ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	629	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	630	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,udpLength.all, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	631	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	632	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	633	} else if ( testFound ) {
nixnax	171:46b36d4edd1d	634	unsigned int sI = __REV( ppp.ip->srcAdrR );
nixnax	171:46b36d4edd1d	635	unsigned int dI = __REV( ppp.ip->dstAdrR );
nixnax	171:46b36d4edd1d	636	unsigned int sp = __REV16( ppp.udp->srcPortR );
nixnax	171:46b36d4edd1d	637	unsigned int dp = __REV16( ppp.udp->dstPortR );
nixnax	172:449dd7a28955	638	int n=sprintf(ppp.pkt.buf+200,"Response Count %d\n", ppp.responseCounter);
nixnax	171:46b36d4edd1d	639	sendUdp(dI,sI,dp,sp,ppp.pkt.buf+200,n); // build a udp packet from the ground up
nixnax	146:a45f49a2b29c	640	}
nixnax	146:a45f49a2b29c	641	}
nixnax	142:54d1543e23e5	642	}
nixnax	142:54d1543e23e5	643
nixnax	174:e5a3f16421a5	644	/// UDP demo that sends a udp packet containing a character received from the second debug serial port.
nixnax	174:e5a3f16421a5	645	/// Sends a 48 byte IP/UDP header for every 1 byte of data so line-mode would probably be better.
nixnax	178:3f17aa0ce5ce	646	/// If you want ip packets from ppp blinky to be routed to other networks, ensure you have ip routing enabled.
nixnax	178:3f17aa0ce5ce	647	/// See http://www.wikihow.com/Enable-IP-Routing.
nixnax	179:ba2b2ddd0da5	648	/// Also ensure that the firewall on the receiving machine has the receiving UDP port (12345 in this example) enabled.
nixnax	179:ba2b2ddd0da5	649	/// The netcat UDP receive command on the remote host would be: nc -ul 12345
nixnax	174:e5a3f16421a5	650	void sendUdpData()
nixnax	174:e5a3f16421a5	651	{
nixnax	174:e5a3f16421a5	652	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	179:ba2b2ddd0da5	653	if (ppp.online) {
nixnax	179:ba2b2ddd0da5	654	if (xx.readable()) {
nixnax	179:ba2b2ddd0da5	655	char inchar = xx.getc();
nixnax	179:ba2b2ddd0da5	656	xx.putc( inchar ); // echo the received character on the debug serial port
nixnax	179:ba2b2ddd0da5	657	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	658	}
nixnax	174:e5a3f16421a5	659	}
nixnax	174:e5a3f16421a5	660	#endif
nixnax	174:e5a3f16421a5	661	}
nixnax	174:e5a3f16421a5	662
nixnax	142:54d1543e23e5	663	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	664	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	665	{
nixnax	165:c47826d07e0d	666	struct {
nixnax	165:c47826d07e0d	667	unsigned int all; // length of entire ip packet
nixnax	165:c47826d07e0d	668	unsigned int header; // length of ip header
nixnax	165:c47826d07e0d	669	} ipLength;
nixnax	165:c47826d07e0d	670	struct {
nixnax	165:c47826d07e0d	671	unsigned int all; // length of entire udp packet
nixnax	165:c47826d07e0d	672	unsigned int data; // length of udp data segment
nixnax	165:c47826d07e0d	673	} icmpLength;
nixnax	165:c47826d07e0d	674	ipLength.all = __REV16( ppp.ip->lengthR ); // length of ip packet
nixnax	165:c47826d07e0d	675	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	165:c47826d07e0d	676	ppp.icmpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	165:c47826d07e0d	677	icmpLength.all = ipLength.all - ipLength.header; // length of icmp packet
nixnax	165:c47826d07e0d	678	icmpLength.data = icmpLength.all - 8; // length of icmp data
nixnax	142:54d1543e23e5	679	#define ICMP_TYPE_PING_REQUEST 8
nixnax	165:c47826d07e0d	680	if ( ppp.icmp->type == ICMP_TYPE_PING_REQUEST ) {
nixnax	165:c47826d07e0d	681	ppp.ip->ttl--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	682	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	167:ff8a2d8beeb1	683	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	684	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	165:c47826d07e0d	685	int icmpIdent = __REV16( ppp.ip->identR ); // byte reversed - big endian
nixnax	165:c47826d07e0d	686	int icmpSequence = __REV16( ppp.icmp->sequenceR ); // byte reversed - big endian
nixnax	142:54d1543e23e5	687	if(1) {
nixnax	142:54d1543e23e5	688	char pbuf[50];
nixnax	210:a2a651249a9a	689
nixnax	142:54d1543e23e5	690	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	221:1d7c32d8256b	691	debugPuts( pbuf );
nixnax	210:a2a651249a9a	692
nixnax	142:54d1543e23e5	693	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	210:a2a651249a9a	694
nixnax	221:1d7c32d8256b	695	debugPuts( pbuf );
nixnax	142:54d1543e23e5	696	}
nixnax	142:54d1543e23e5	697	#endif
nixnax	147:0f40005cbc5f	698	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	699	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	700	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	165:c47826d07e0d	701	ppp.icmp->type = ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	165:c47826d07e0d	702	ppp.icmp->checkSumR = 0; // zero the checksum for recalculation
nixnax	165:c47826d07e0d	703	unsigned int sum = dataCheckSum(ppp.icmpStart, icmpLength.all, 1); // icmp checksum
nixnax	165:c47826d07e0d	704	ppp.icmp->checkSumR = __REV16( sum ); // save big-endian icmp checksum
nixnax	142:54d1543e23e5	705
nixnax	165:c47826d07e0d	706	int printSize = icmpLength.data; // exclude size of icmp header
nixnax	142:54d1543e23e5	707	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	708	if (0) {
nixnax	142:54d1543e23e5	709	for (int i=0; i<printSize; i++) {
nixnax	165:c47826d07e0d	710	char ch = ppp.icmp->data[i];
nixnax	142:54d1543e23e5	711	if (ch>31 && ch<127) {
nixnax	221:1d7c32d8256b	712	debugPutc(ch);
nixnax	142:54d1543e23e5	713	} else {
nixnax	221:1d7c32d8256b	714	debugPutc('_');
nixnax	142:54d1543e23e5	715	}
nixnax	142:54d1543e23e5	716	}
nixnax	221:1d7c32d8256b	717	debugPutc('\n');
nixnax	142:54d1543e23e5	718	}
nixnax	144:01d98cf7738e	719	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	720	} else {
nixnax	142:54d1543e23e5	721	if (v0) {
nixnax	165:c47826d07e0d	722	debugPrintf("ICMP type=%x \n", ppp.icmp->type);
nixnax	142:54d1543e23e5	723	}
nixnax	142:54d1543e23e5	724	}
nixnax	142:54d1543e23e5	725	}
nixnax	142:54d1543e23e5	726
nixnax	142:54d1543e23e5	727	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	728	void IGMPpacket()
nixnax	142:54d1543e23e5	729	{
nixnax	142:54d1543e23e5	730	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	731	}
nixnax	142:54d1543e23e5	732
nixnax	142:54d1543e23e5	733	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	734	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	735	{
nixnax	142:54d1543e23e5	736	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	210:a2a651249a9a	737
nixnax	155:9c6a1d249e26	738	int IPv4Id = __REV16(ppp.ip->identR);
nixnax	152:025c73b6c0a9	739	char pbuf[80]; // local print buffer
nixnax	142:54d1543e23e5	740	int n=0;
nixnax	142:54d1543e23e5	741	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	742	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	743	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	744	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	167:ff8a2d8beeb1	745	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	746	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	142:54d1543e23e5	747	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	748	#endif
nixnax	221:1d7c32d8256b	749	debugPuts( pbuf );
nixnax	142:54d1543e23e5	750	#ifndef TCP_HEADER_DUMP_YES
nixnax	221:1d7c32d8256b	751	debugPuts('\x1b[30m\n'); // if there's no TCP header dump we terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	752	#endif
nixnax	142:54d1543e23e5	753	#endif
nixnax	142:54d1543e23e5	754	}
nixnax	142:54d1543e23e5	755
nixnax	142:54d1543e23e5	756	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	757	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	758	{
nixnax	142:54d1543e23e5	759	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	155:9c6a1d249e26	760	char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	761	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	762	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	155:9c6a1d249e26	763	memset(flagString,'.', 8); // fill string with "........"
nixnax	156:163c23249731	764	if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax	156:163c23249731	765	if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax	156:163c23249731	766	if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax	156:163c23249731	767	if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax	156:163c23249731	768	if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax	156:163c23249731	769	if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax	156:163c23249731	770	if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax	156:163c23249731	771	if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax	155:9c6a1d249e26	772	flagString[8]=0; // null terminate string
nixnax	142:54d1543e23e5	773	#else
nixnax	156:163c23249731	774	if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax	156:163c23249731	775	if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax	156:163c23249731	776	if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax	156:163c23249731	777	if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax	156:163c23249731	778	if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax	155:9c6a1d249e26	779	flagString[1]=0; // null terminate string
nixnax	142:54d1543e23e5	780	#endif
nixnax	221:1d7c32d8256b	781	debugPuts( flagString );
nixnax	142:54d1543e23e5	782	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	783	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	221:1d7c32d8256b	784	debugPuts("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	160:bd701ad564cb	785	#else
nixnax	221:1d7c32d8256b	786	debugPuts("\x1b[30m"); // write a black color after every packet
nixnax	142:54d1543e23e5	787	#endif
nixnax	156:163c23249731	788	if( outGoing && ppp.tcp->flag.fin ) { // ACK/FIN - if this is an outgoing FIN it's the end of a tcp conversation
nixnax	221:1d7c32d8256b	789	debugPutc('\n'); // insert an extra new line to mark the end (except for final ack) of an HTTP conversation
nixnax	142:54d1543e23e5	790	}
nixnax	142:54d1543e23e5	791	#endif
nixnax	142:54d1543e23e5	792	}
nixnax	142:54d1543e23e5	793
nixnax	143:c5019f856a56	794	/// Encode a buffer in base-64
nixnax	184:4133f557d4d4	795	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	796	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	797	{
nixnax	142:54d1543e23e5	798	int i,j,a,b,c;
nixnax	142:54d1543e23e5	799	i=0;
nixnax	142:54d1543e23e5	800	j=0;
nixnax	142:54d1543e23e5	801	while(1) {
nixnax	142:54d1543e23e5	802	if (i<len) {
nixnax	142:54d1543e23e5	803	a = in[i++];
nixnax	142:54d1543e23e5	804	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	805	} else break;
nixnax	142:54d1543e23e5	806	if (i<len) {
nixnax	142:54d1543e23e5	807	b = in[i++];
nixnax	142:54d1543e23e5	808	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	809	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	810	} else out[j++] = '=';
nixnax	142:54d1543e23e5	811	if (i<len) {
nixnax	142:54d1543e23e5	812	c = in[i++];
nixnax	142:54d1543e23e5	813	j--;
nixnax	142:54d1543e23e5	814	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	815	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	816	} else out[j++] = '=';
nixnax	142:54d1543e23e5	817	}
nixnax	142:54d1543e23e5	818	out[j]=0;
nixnax	142:54d1543e23e5	819	}
nixnax	142:54d1543e23e5	820
nixnax	160:bd701ad564cb	821	/// Handle a request for an http websocket.
nixnax	160:bd701ad564cb	822	/// 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	823	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	824	{
nixnax	142:54d1543e23e5	825	int n=0; // byte counter
nixnax	184:4133f557d4d4	826	char * key = strstr(dataStart, "Sec-WebSocket-Key:"); // search for the key in the payload
nixnax	142:54d1543e23e5	827	if (key != NULL) {
nixnax	184:4133f557d4d4	828	key = key + 18; // skip over the key ident string "Sec-WebSocket-Key:"
nixnax	221:1d7c32d8256b	829	if (v0) debugPuts("WebSocket Request\n");
nixnax	184:4133f557d4d4	830	while ( strchr(lut, *key) == NULL) key++; // skip non-valid base-64 characters (whitespace)
nixnax	184:4133f557d4d4	831	char challenge [80];
nixnax	184:4133f557d4d4	832	int i=0;
nixnax	184:4133f557d4d4	833	char * copyTo = challenge;
nixnax	184:4133f557d4d4	834	while (strchr(lut, *key) != NULL) { // copy while we see valid base-64 characters
nixnax	184:4133f557d4d4	835	if (i++ >40) break; // prevent buffer overflow
nixnax	184:4133f557d4d4	836	copyTo++ = key++; // copy next valid base-64 character
nixnax	184:4133f557d4d4	837	}
nixnax	184:4133f557d4d4	838	strcpy(copyTo,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"); // append websocket gui code
nixnax	184:4133f557d4d4	839	if (0) debugPrintf("Challenge is %s\n", challenge); // the string we hash for the challenge
nixnax	142:54d1543e23e5	840	char shaOutput [20]; // sha1 output
nixnax	184:4133f557d4d4	841	sha1( shaOutput, challenge, strlen(challenge)); // hash the challenge
nixnax	142:54d1543e23e5	842	char encOut[50];
nixnax	184:4133f557d4d4	843	enc64( shaOutput, encOut, 20); // base-64 encode
nixnax	142:54d1543e23e5	844	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	845	char * version = challenge;
nixnax	184:4133f557d4d4	846	strncpy(version, versionstring,70); // copy their version string
nixnax	142:54d1543e23e5	847	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	848	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	849	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	850	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	851	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	852	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	853	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	854	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	855	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	856	}
nixnax	142:54d1543e23e5	857	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	858	}
nixnax	142:54d1543e23e5	859
nixnax	142:54d1543e23e5	860	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	861	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	862	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	863	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	864	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	865
nixnax	142:54d1543e23e5	866	/// respond to an HTTP request
nixnax	185:4cd8f91e9d49	867	int httpResponse(char * dataStart, int * flags)
nixnax	142:54d1543e23e5	868	{
nixnax	142:54d1543e23e5	869	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	870	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	160:bd701ad564cb	871	if (n>0) return n; // if n>0 we already have a response, so return
nixnax	142:54d1543e23e5	872
nixnax	142:54d1543e23e5	873	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	874	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	875	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	185:4cd8f91e9d49	876	*flags = TCP_FLAG_ACK \| TCP_FLAG_FIN; // the default case is that we close the connection
nixnax	142:54d1543e23e5	877
nixnax	142:54d1543e23e5	878	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	879	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	880	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	881	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	882	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	210:a2a651249a9a	883	if( (httpGetRoot==0) \|\| (httpGetx==0) \|\| (httpGet5 == 'w') ) {
nixnax	142:54d1543e23e5	884	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	885	} else {
nixnax	142:54d1543e23e5	886	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	887	}
nixnax	142:54d1543e23e5	888	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	889	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	890	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	891	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	217:86498f9ab967	892	#define SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	893	#ifdef SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	894	// 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	210:a2a651249a9a	895	n=n+sprintf(n+dataStart,"Maxbuflevel: %d\r\n", ppp.rx.maxbuflevel);
nixnax	210:a2a651249a9a	896	#endif
nixnax	142:54d1543e23e5	897	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	898	nHeader=n; // size of HTTP header
nixnax	210:a2a651249a9a	899
nixnax	142:54d1543e23e5	900	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	901	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	902	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	903	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	185:4cd8f91e9d49	904
nixnax	210:a2a651249a9a	905	} else if ( httpGet5 == 'w' ) { // "w" is a special page for websocket demo
nixnax	142:54d1543e23e5	906	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	907	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	185:4cd8f91e9d49	908	*flags = TCP_FLAG_ACK \| TCP_FLAG_PSH; // for a websocket page we do NOT close the connection
nixnax	142:54d1543e23e5	909	} else {
nixnax	142:54d1543e23e5	910	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	911	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	912	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	913	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	914	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	915	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	916	#else
nixnax	142:54d1543e23e5	917	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	167:ff8a2d8beeb1	918	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	919	}
nixnax	142:54d1543e23e5	920	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	921	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	922	#endif
nixnax	142:54d1543e23e5	923	} else {
nixnax	142:54d1543e23e5	924	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	925	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	926	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	927	}
nixnax	142:54d1543e23e5	928	}
nixnax	142:54d1543e23e5	929	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	930	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	931	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	932	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	933	return n; // total byte size of our response
nixnax	142:54d1543e23e5	934	}
nixnax	142:54d1543e23e5	935
nixnax	160:bd701ad564cb	936	/// Handle TCP data that is not an HTTP GET.
nixnax	160:bd701ad564cb	937	/// This is handy when for example you want to use netcat (nc.exe) to talk to PPP-Blinky.
nixnax	160:bd701ad564cb	938	/// This could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	939	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	940	{
nixnax	142:54d1543e23e5	941	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	942	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	160:bd701ad564cb	943	char mask [4];
nixnax	160:bd701ad564cb	944	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	160:bd701ad564cb	945	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	160:bd701ad564cb	946	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	947	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	948	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	949	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	160:bd701ad564cb	950	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	951	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	952	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	953	dataStart[1]=0; // we don't have mask bytes on
nixnax	160:bd701ad564cb	954	} else {
nixnax	184:4133f557d4d4	955	if ( len > 1 ) { // we assume a length of 1 is a keep-alive or push packet
nixnax	221:1d7c32d8256b	956	if (v1) debugPuts("TCP data received\n"); // all other tcp push packets
nixnax	184:4133f557d4d4	957	}
nixnax	163:d1b4328e9f08	958	}
nixnax	142:54d1543e23e5	959	return n; // total byte size of our response
nixnax	142:54d1543e23e5	960	}
nixnax	142:54d1543e23e5	961
nixnax	173:6774a0c851c4	962	/// dump the TCP data to the debug serial port
nixnax	173:6774a0c851c4	963	void dumpDataTCP(int outGoing)
nixnax	173:6774a0c851c4	964	{
nixnax	173:6774a0c851c4	965	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	173:6774a0c851c4	966	if (v2) {
nixnax	173:6774a0c851c4	967	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	173:6774a0c851c4	968	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	969	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax	173:6774a0c851c4	970	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	971	ppp.tcpData = ppp.tcpStart + headerSizeTcp; // start of tcp data
nixnax	173:6774a0c851c4	972	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	173:6774a0c851c4	973	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	173:6774a0c851c4	974	char pbuf[80]; // local print buffer
nixnax	173:6774a0c851c4	975	int n=0;
nixnax	210:a2a651249a9a	976
nixnax	173:6774a0c851c4	977	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	210:a2a651249a9a	978
nixnax	173:6774a0c851c4	979	n=n+sprintf(pbuf+n, "IP:%d ipHeader:%d tcpHeader:%d tcpData:%d\n", packetLengthIp, headerSizeIp, headerSizeTcp, tcpDataSize); // 1 for more verbose
nixnax	221:1d7c32d8256b	980	if (n>70) debugPuts("n>pbuf overflow in dumpDataTCP()\n");
nixnax	210:a2a651249a9a	981
nixnax	221:1d7c32d8256b	982	debugPuts( pbuf );
nixnax	173:6774a0c851c4	983	if (tcpDataSize > 0) {
nixnax	173:6774a0c851c4	984	ppp.tcpData[tcpDataSize]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	221:1d7c32d8256b	985	debugPuts( ppp.tcpData ); // print the tcp payload data
nixnax	221:1d7c32d8256b	986	debugPuts("\n");
nixnax	173:6774a0c851c4	987	}
nixnax	221:1d7c32d8256b	988	debugPuts( "\x1b[30m" ); // VT100 color code, print black
nixnax	173:6774a0c851c4	989	}
nixnax	173:6774a0c851c4	990	#endif
nixnax	173:6774a0c851c4	991	}
nixnax	173:6774a0c851c4	992
nixnax	142:54d1543e23e5	993	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	994	/// 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	995	void tcpHandler()
nixnax	142:54d1543e23e5	996	{
nixnax	154:18b2bd92f557	997	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	154:18b2bd92f557	998	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	999	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate TCP header start
nixnax	154:18b2bd92f557	1000	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	154:18b2bd92f557	1001	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	1002	char * tcpDataIn = ppp.tcpStart + headerSizeTcp; // start of data TCP data after TCP header
nixnax	154:18b2bd92f557	1003	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	154:18b2bd92f557	1004
nixnax	154:18b2bd92f557	1005	unsigned int seq_in = __REV(ppp.tcp->seqTcpR);
nixnax	154:18b2bd92f557	1006	unsigned int ack_in = __REV(ppp.tcp->ackTcpR);
nixnax	142:54d1543e23e5	1007	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	1008	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	1009
nixnax	142:54d1543e23e5	1010	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	173:6774a0c851c4	1011	headerSizeIp=20;
nixnax	173:6774a0c851c4	1012	ppp.ip->headerLength = headerSizeIp/4; // ip header is 20 bytes long
nixnax	173:6774a0c851c4	1013	ppp.ip->lengthR = __REV(40); // 20 ip header + 20 tcp header
nixnax	173:6774a0c851c4	1014	//tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	154:18b2bd92f557	1015	headerSizeTcp = 20; // shorten outgoing TCP header size 20 bytes
nixnax	173:6774a0c851c4	1016	ppp.tcpStart = ppp.ipStart + headerSizeIp; // recalc TCP header start
nixnax	154:18b2bd92f557	1017	ppp.tcp->offset = (headerSizeTcp/4);
nixnax	173:6774a0c851c4	1018	char * tcpDataOut = ppp.tcpStart + headerSizeTcp; // start of outgoing data
nixnax	142:54d1543e23e5	1019
nixnax	142:54d1543e23e5	1020	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	1021	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	160:bd701ad564cb	1022
nixnax	185:4cd8f91e9d49	1023	ppp.tcp->windowR = __REV16( 1200 ); // set tcp window size to 1200 bytes
nixnax	142:54d1543e23e5	1024
nixnax	142:54d1543e23e5	1025	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	1026
nixnax	156:163c23249731	1027	switch ( ppp.tcp->flag.All ) {
nixnax	142:54d1543e23e5	1028	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1029	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1030	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1031	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1032	break;
nixnax	184:4133f557d4d4	1033	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1034	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	184:4133f557d4d4	1035	if ( (ppp.tcp->flag.All == TCP_FLAG_ACK) && (tcpDataSize == 0)) return; // handle zero-size ack messages by ignoring them
nixnax	142:54d1543e23e5	1036	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	179:ba2b2ddd0da5	1037	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // we have data, set the PSH flag
nixnax	185:4cd8f91e9d49	1038	dataLen = httpResponse(tcpDataOut, &flagsOut); // send an http response
nixnax	142:54d1543e23e5	1039	} else {
nixnax	158:841592aed956	1040	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax	179:ba2b2ddd0da5	1041	if (dataLen > 0) flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // if we have any data set the PSH flag
nixnax	142:54d1543e23e5	1042	}
nixnax	142:54d1543e23e5	1043	break;
nixnax	142:54d1543e23e5	1044	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1045	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1046	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1047	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1048	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1049	break;
nixnax	142:54d1543e23e5	1050	default:
nixnax	179:ba2b2ddd0da5	1051	return; // ignore all other packets
nixnax	142:54d1543e23e5	1052	} // switch
nixnax	142:54d1543e23e5	1053
nixnax	142:54d1543e23e5	1054	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1055	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1056	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1057	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1058
nixnax	158:841592aed956	1059	ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	158:841592aed956	1060	ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	160:bd701ad564cb	1061
nixnax	156:163c23249731	1062	ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1063
nixnax	159:4d1bf96a59cd	1064	// recalculate all the header sizes
nixnax	154:18b2bd92f557	1065	tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax	154:18b2bd92f557	1066	int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax	159:4d1bf96a59cd	1067	ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax	142:54d1543e23e5	1068	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	1069
nixnax	142:54d1543e23e5	1070	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1071	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	170:3d3b2126181c	1072	checkSumPseudoHeader( tcpSize ); // get the TCP pseudo-header checksum
nixnax	159:4d1bf96a59cd	1073	ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	161:d59f778bc8ab	1074	unsigned int pseudoHeaderSum=dataCheckSum(ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax	159:4d1bf96a59cd	1075	ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	160:bd701ad564cb	1076
nixnax	170:3d3b2126181c	1077	dumpHeaderIP(1); // dump outgoing IP header before sending the frame
nixnax	170:3d3b2126181c	1078	dumpHeaderTCP(1); // dump outgoing TCP header before sending the frame
nixnax	173:6774a0c851c4	1079	dumpDataTCP(1); // dump outgoing TCP data before sending the frame
nixnax	182:f039ec218c9f	1080	if (0) wait_ms(45); // 45 ms delay before sending frame - a typical internet delay time
nixnax	144:01d98cf7738e	1081	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1082	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1083	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1084	}
nixnax	142:54d1543e23e5	1085
nixnax	142:54d1543e23e5	1086	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1087	void TCPpacket()
nixnax	142:54d1543e23e5	1088	{
nixnax	173:6774a0c851c4	1089	dumpHeaderIP(0); // dump incoming packet IP header
nixnax	173:6774a0c851c4	1090	dumpHeaderTCP(0); // dump incoming packet TCP header
nixnax	173:6774a0c851c4	1091	dumpDataTCP(0); // dump incoming packet data
nixnax	142:54d1543e23e5	1092	tcpHandler();
nixnax	142:54d1543e23e5	1093	}
nixnax	142:54d1543e23e5	1094
nixnax	142:54d1543e23e5	1095	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1096	void otherProtocol()
nixnax	142:54d1543e23e5	1097	{
nixnax	142:54d1543e23e5	1098	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1099	}
nixnax	142:54d1543e23e5	1100
nixnax	142:54d1543e23e5	1101	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1102	void IPframe()
nixnax	142:54d1543e23e5	1103	{
nixnax	167:ff8a2d8beeb1	1104	int protocol = ppp.ip->protocol;
nixnax	142:54d1543e23e5	1105	switch (protocol) {
nixnax	142:54d1543e23e5	1106	case 1:
nixnax	142:54d1543e23e5	1107	ICMPpacket();
nixnax	142:54d1543e23e5	1108	break;
nixnax	142:54d1543e23e5	1109	case 2:
nixnax	142:54d1543e23e5	1110	IGMPpacket();
nixnax	142:54d1543e23e5	1111	break;
nixnax	142:54d1543e23e5	1112	case 17:
nixnax	142:54d1543e23e5	1113	UDPpacket();
nixnax	142:54d1543e23e5	1114	break;
nixnax	142:54d1543e23e5	1115	case 6:
nixnax	142:54d1543e23e5	1116	TCPpacket();
nixnax	142:54d1543e23e5	1117	break;
nixnax	142:54d1543e23e5	1118	default:
nixnax	142:54d1543e23e5	1119	otherProtocol();
nixnax	142:54d1543e23e5	1120	}
nixnax	142:54d1543e23e5	1121	}
nixnax	142:54d1543e23e5	1122
nixnax	142:54d1543e23e5	1123	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1124	void LCPconfReq()
nixnax	142:54d1543e23e5	1125	{
nixnax	142:54d1543e23e5	1126	debugPrintf("LCP Config ");
nixnax	175:b4e6f8a6fe00	1127	if ( ppp.lcp->lengthR != __REV16(4) ) {
nixnax	175:b4e6f8a6fe00	1128	ppp.lcp->code=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1129	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1130	sendPppFrame();
nixnax	142:54d1543e23e5	1131	} else {
nixnax	175:b4e6f8a6fe00	1132	ppp.lcp->code=2; // ack zero conf
nixnax	142:54d1543e23e5	1133	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1134	sendPppFrame();
nixnax	142:54d1543e23e5	1135	debugPrintf("LCP Ask\n");
nixnax	175:b4e6f8a6fe00	1136	ppp.lcp->code=1; // request no options
nixnax	144:01d98cf7738e	1137	sendPppFrame();
nixnax	142:54d1543e23e5	1138	}
nixnax	142:54d1543e23e5	1139	}
nixnax	142:54d1543e23e5	1140
nixnax	142:54d1543e23e5	1141	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1142	void LCPconfAck()
nixnax	142:54d1543e23e5	1143	{
nixnax	142:54d1543e23e5	1144	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1145	}
nixnax	142:54d1543e23e5	1146
nixnax	143:c5019f856a56	1147	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1148	void LCPend()
nixnax	142:54d1543e23e5	1149	{
nixnax	175:b4e6f8a6fe00	1150	ppp.lcp->code=6; // end
nixnax	144:01d98cf7738e	1151	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1152	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1153	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1154	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1155	}
nixnax	142:54d1543e23e5	1156
nixnax	142:54d1543e23e5	1157	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1158	void LCPother()
nixnax	142:54d1543e23e5	1159	{
nixnax	142:54d1543e23e5	1160	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1161	dumpPPPFrame();
nixnax	142:54d1543e23e5	1162	}
nixnax	142:54d1543e23e5	1163
nixnax	142:54d1543e23e5	1164	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1165	void LCPframe()
nixnax	142:54d1543e23e5	1166	{
nixnax	175:b4e6f8a6fe00	1167	int code = ppp.lcp->code;
nixnax	142:54d1543e23e5	1168	switch (code) {
nixnax	142:54d1543e23e5	1169	case 1:
nixnax	142:54d1543e23e5	1170	LCPconfReq();
nixnax	142:54d1543e23e5	1171	break; // config request
nixnax	142:54d1543e23e5	1172	case 2:
nixnax	142:54d1543e23e5	1173	LCPconfAck();
nixnax	142:54d1543e23e5	1174	break; // config ack
nixnax	142:54d1543e23e5	1175	case 5:
nixnax	142:54d1543e23e5	1176	LCPend();
nixnax	142:54d1543e23e5	1177	break; // end connection
nixnax	142:54d1543e23e5	1178	default:
nixnax	142:54d1543e23e5	1179	LCPother();
nixnax	142:54d1543e23e5	1180	}
nixnax	142:54d1543e23e5	1181	}
nixnax	142:54d1543e23e5	1182
nixnax	142:54d1543e23e5	1183	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1184	void discardedFrame()
nixnax	142:54d1543e23e5	1185	{
nixnax	142:54d1543e23e5	1186	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	1187	}
nixnax	142:54d1543e23e5	1188
nixnax	142:54d1543e23e5	1189	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1190	void determinePacketType()
nixnax	142:54d1543e23e5	1191	{
nixnax	167:ff8a2d8beeb1	1192	if ( ppp.ppp->address != 0xff ) {
nixnax	167:ff8a2d8beeb1	1193	debugPrintf("Unexpected: PPP address != ff\n");
nixnax	142:54d1543e23e5	1194	return;
nixnax	142:54d1543e23e5	1195	}
nixnax	167:ff8a2d8beeb1	1196	if ( ppp.ppp->control != 3 ) {
nixnax	167:ff8a2d8beeb1	1197	debugPrintf("Unexpected: PPP control != 3\n");
nixnax	142:54d1543e23e5	1198	return;
nixnax	142:54d1543e23e5	1199	}
nixnax	167:ff8a2d8beeb1	1200	unsigned int protocol = __REV16( ppp.ppp->protocolR );
nixnax	167:ff8a2d8beeb1	1201	switch ( protocol ) {
nixnax	167:ff8a2d8beeb1	1202	case 0xc021:
nixnax	142:54d1543e23e5	1203	LCPframe();
nixnax	142:54d1543e23e5	1204	break; // link control
nixnax	167:ff8a2d8beeb1	1205	case 0x8021:
nixnax	142:54d1543e23e5	1206	IPCPframe();
nixnax	142:54d1543e23e5	1207	break; // IP control
nixnax	167:ff8a2d8beeb1	1208	case 0x0021:
nixnax	142:54d1543e23e5	1209	IPframe();
nixnax	142:54d1543e23e5	1210	break; // IP itself
nixnax	142:54d1543e23e5	1211	default:
nixnax	142:54d1543e23e5	1212	discardedFrame();
nixnax	142:54d1543e23e5	1213	}
nixnax	142:54d1543e23e5	1214	}
nixnax	142:54d1543e23e5	1215
nixnax	146:a45f49a2b29c	1216	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1217	void sniff()
nixnax	146:a45f49a2b29c	1218	{
nixnax	221:1d7c32d8256b	1219	if ( pc.readable() ) debugPuts( "Sniff - Char available!\n" ); // if this prints anything it means there is a character in the serial receive buffer
nixnax	146:a45f49a2b29c	1220	}
nixnax	146:a45f49a2b29c	1221
nixnax	142:54d1543e23e5	1222	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1223	void waitForPppFrame()
nixnax	142:54d1543e23e5	1224	{
nixnax	142:54d1543e23e5	1225	while(1) {
nixnax	142:54d1543e23e5	1226	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1227	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1228	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1229	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1230	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1231	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1232	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	181:bcfe7fe2142d	1233	ppp.firstFrame=0; // clear first frame flag
nixnax	142:54d1543e23e5	1234	} else {
nixnax	142:54d1543e23e5	1235	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1236	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1237	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1238	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1239	break;
nixnax	142:54d1543e23e5	1240	}
nixnax	142:54d1543e23e5	1241	}
nixnax	142:54d1543e23e5	1242	}
nixnax	210:a2a651249a9a	1243	// change below to YES to enable the serial to UDP demo
nixnax	210:a2a651249a9a	1244	#define SERIAL_TO_UDP_NO
nixnax	210:a2a651249a9a	1245	#ifdef SERIAL_TO_UDP_YES
nixnax	210:a2a651249a9a	1246	sendUdpData(); // demo that sends characters received on the DEBUG serial port via UDP to another host
nixnax	210:a2a651249a9a	1247	#endif
nixnax	142:54d1543e23e5	1248	}
nixnax	142:54d1543e23e5	1249	}
nixnax	142:54d1543e23e5	1250
nixnax	209:aa514cd631ee	1251	/// 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	209:aa514cd631ee	1252	// 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	1253	void waitForPcConnectString()
nixnax	142:54d1543e23e5	1254	{
nixnax	142:54d1543e23e5	1255	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1256	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1257	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1258	if (found1 != NULL) {
nixnax	209:aa514cd631ee	1259	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	208:73086736610a	1260	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	142:54d1543e23e5	1261	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1262	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1263	}
nixnax	142:54d1543e23e5	1264	}
nixnax	142:54d1543e23e5	1265	}
nixnax	142:54d1543e23e5	1266
nixnax	144:01d98cf7738e	1267	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1268	void initializePpp()
nixnax	142:54d1543e23e5	1269	{
nixnax	210:a2a651249a9a	1270	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	144:01d98cf7738e	1271	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	184:4133f557d4d4	1272	debugPrintf("\x1b[2J\x1b[H\x1b[30m");
nixnax	184:4133f557d4d4	1273	wait_ms(200); // a brief wait so a human can see the reset event
nixnax	184:4133f557d4d4	1274	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	210:a2a651249a9a	1275	#endif
nixnax	179:ba2b2ddd0da5	1276	pppInitStruct(); // initialize all the variables/properties/buffers
nixnax	179:ba2b2ddd0da5	1277	pc.baud(115200); // pc serial port acting as a dial-up modem - for PPP traffic
nixnax	179:ba2b2ddd0da5	1278	pc.attach(&pppReceiveHandler, RawSerial::RxIrq); // set up serial port receive interrupt handler
nixnax	143:c5019f856a56	1279	}

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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.