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@253:ee1044976b2c, 2019-01-17 (annotated)

Committer:: nixnax
Date:: Thu Jan 17 16:13:36 2019 +0000
Revision:: 253:ee1044976b2c
Parent:: 252:b3c8c5699153
Child:: 254:7345c9a6f4c2

PPP frames were double-counted.

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	249:9ff0e20325f7	18	// https://en.wikipedia.org/wiki/Favicon (see also html5 <link> tag)
nixnax	142:54d1543e23e5	19
nixnax	142:54d1543e23e5	20	// Handy tools
nixnax	142:54d1543e23e5	21	// 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	22	// https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax	142:54d1543e23e5	23	// http://pingtester.net/ - nice tool for high rate ping testing
nixnax	142:54d1543e23e5	24	// 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	25	// https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax	142:54d1543e23e5	26	// https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax	142:54d1543e23e5	27	// 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	28
nixnax	142:54d1543e23e5	29	// Connecting PPP-Blinky to Linux
nixnax	142:54d1543e23e5	30	// PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax	142:54d1543e23e5	31	// pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax	142:54d1543e23e5	32	// 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	33	// See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax	142:54d1543e23e5	34
nixnax	142:54d1543e23e5	35	// Special pages when PPP-Blinky is running
nixnax	142:54d1543e23e5	36	// 172.10.10.2 root page
nixnax	182:f039ec218c9f	37	// 172.10.10.2/x returns the number of ppp frames sent - this is handy for testing
nixnax	182:f039ec218c9f	38	// 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	39	// 172.10.10.2/ws a simple WebSocket demo
nixnax	182:f039ec218c9f	40	// http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle, showing cross-domain access
nixnax	207:28cd834b785d	41
nixnax	142:54d1543e23e5	42	// Ok, enough talking, time to check out some code!!
nixnax	142:54d1543e23e5	43
nixnax	142:54d1543e23e5	44	#include "ppp-blinky.h"
nixnax	142:54d1543e23e5	45
nixnax	142:54d1543e23e5	46	// The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax	146:a45f49a2b29c	47	// 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	48	// Using the second serial port will slow down packet response time
nixnax	142:54d1543e23e5	49	// Note - the LPC11U24 does NOT have a second serial port
nixnax	146:a45f49a2b29c	50
nixnax	183:6d3ba874b267	51	#define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax	142:54d1543e23e5	52
nixnax	142:54d1543e23e5	53	// here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax	142:54d1543e23e5	54	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	55	#if defined(TARGET_LPC1768)
nixnax	179:ba2b2ddd0da5	56	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	57	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	179:ba2b2ddd0da5	58	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	59	#elif defined(TARGET_NUCLEO_L432KC)
nixnax	196:8791e241be80	60	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	61	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	62	#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	63	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	179:ba2b2ddd0da5	64	RawSerial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	193:48072570f41d	65	#elif defined(TARGET_KW41Z)
nixnax	194:5b23ebfb3626	66	RawSerial xx(PTC3, PTC2); // Second serial port on FRDM-KW41Z board
nixnax	142:54d1543e23e5	67	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	68	// 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	226:4898247048c7	69	RawSerial xx(p9, p10); // change this to YOUR board's second serial port pin definition - and please send it to me if it works!!!
nixnax	142:54d1543e23e5	70	#else
nixnax	142:54d1543e23e5	71	#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	72	#endif
nixnax	179:ba2b2ddd0da5	73	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we can print debug messages */
nixnax	142:54d1543e23e5	74	#define debugPutc(x...) xx.putc(x)
nixnax	221:1d7c32d8256b	75	#define debugPuts(x...) xx.puts(x)
nixnax	142:54d1543e23e5	76	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	77	#else
nixnax	142:54d1543e23e5	78	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	79	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	80	#define debugPutc(x...) {}
nixnax	221:1d7c32d8256b	81	#define debugPuts(x...) {}
nixnax	142:54d1543e23e5	82	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	83	#endif
nixnax	142:54d1543e23e5	84
nixnax	142:54d1543e23e5	85	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	182:f039ec218c9f	86	#define v0 1
nixnax	142:54d1543e23e5	87	#define v1 0
nixnax	142:54d1543e23e5	88	#define v2 0
nixnax	182:f039ec218c9f	89	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	182:f039ec218c9f	90	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	226:4898247048c7	91	#define DUMP_RECEIVED_PPP_FRAMES_NO /* YES to dump received PPP frames */
nixnax	142:54d1543e23e5	92
nixnax	226:4898247048c7	93	// below is the webpage we serve when we get an HTTP request to root (/)
nixnax	226:4898247048c7	94	// keep size under ~1400 bytes to fit into a single PPP packet
nixnax	249:9ff0e20325f7	95	// the <link rel="icon" ...> tag stops browsers from asking for file favicon.ico
nixnax	142:54d1543e23e5	96
nixnax	142:54d1543e23e5	97	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	98	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	99	<html>\
nixnax	248:5aca1c98fc24	100	<!--Comment-->\
nixnax	142:54d1543e23e5	101	<head>\
nixnax	146:a45f49a2b29c	102	<title>mbed PPP-Blinky</title>\r\n\
nixnax	248:5aca1c98fc24	103	<link rel=\"icon\" href=\"data:image/gif;base64,R0lGODlhAQABAIABAP8AAAAAACwAAAAAAQABAAACAkQBADs=\">\
nixnax	226:4898247048c7	104	<style>\
nixnax	241:dece92cb7296	105	body {font-family:sans-serif; font-size:140%; text-align:center; color:#807070;}\
nixnax	248:5aca1c98fc24	106	</style>\r\n\
nixnax	142:54d1543e23e5	107	</head>\
nixnax	226:4898247048c7	108	<body>\
nixnax	142:54d1543e23e5	109	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	110	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	210:a2a651249a9a	111	<h1><a href=\"/w\">WebSocket Test</a></h1>\
nixnax	245:544cea761769	112	<h1><a href=\"/x?Parameter1=Example\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	113	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	241:dece92cb7296	114	<h1><a href=\"http://jsfiddle.net/d26cyuh2/112/embedded/result\">JSFiddle Demo</a></h1>\
nixnax	252:b3c8c5699153	115	<h1>TCP, LCP & Ping Count: 0000000000</h1>\
nixnax	241:dece92cb7296	116	</body>\
nixnax	245:544cea761769	117	</html>\r\n"; // size = 553 bytes + 1 null byte = 554 bytes
nixnax	142:54d1543e23e5	118
nixnax	167:ff8a2d8beeb1	119	// this is a websocket demo html page we serve when GET /ws is requested
nixnax	226:4898247048c7	120	// it contains some javascript to handle the websocket activities
nixnax	249:9ff0e20325f7	121	// the <link rel="icon" ...> tag stops browsers from asking for file favicon.ico
nixnax	142:54d1543e23e5	122	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	123	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	124	<html>\
nixnax	142:54d1543e23e5	125	<head>\
nixnax	226:4898247048c7	126	<title>mbed PPP-Blinky WebSocket</title>\
nixnax	248:5aca1c98fc24	127	<link rel=\"icon\" href=\"data:image/gif;base64,R0lGODlhAQABAIABAP8AAAAAACwAAAAAAQABAAACAkQBADs=\">\
nixnax	142:54d1543e23e5	128	<script>\
nixnax	142:54d1543e23e5	129	window.onload=function(){\
nixnax	142:54d1543e23e5	130	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	131	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	132	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	133	var ctr=0;\
nixnax	142:54d1543e23e5	134	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	135	btn.onclick=function(){\
nixnax	142:54d1543e23e5	136	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	137	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	138	x.onopen=function(){\
nixnax	226:4898247048c7	139	show(\"Connected to PPP-Blinky WebSocket service at: \"+url);\
nixnax	142:54d1543e23e5	140	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	141	};\
nixnax	226:4898247048c7	142	x.onclose=function(){show(\"WebSocket closed\");};\
nixnax	226:4898247048c7	143	x.onmessage=function(msg){show(\"PPP-Blinky WebSocket service responded with: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	144	} else {\
nixnax	142:54d1543e23e5	145	x.send(ctr);\
nixnax	142:54d1543e23e5	146	ctr=ctr+1;\
nixnax	142:54d1543e23e5	147	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	148	}\
nixnax	142:54d1543e23e5	149	};\
nixnax	142:54d1543e23e5	150	};\
nixnax	142:54d1543e23e5	151	</script>\
nixnax	226:4898247048c7	152	<style>\
nixnax	241:dece92cb7296	153	body {font-family:sans-serif; font-size:140%; text-align:center; color:#807070;}\
nixnax	241:dece92cb7296	154	button {font-size:140%; background-color:#7eeeee; border-radius:15px; border:none; margin-top:20px; }\
nixnax	226:4898247048c7	155	</style>\
nixnax	226:4898247048c7	156	<body>\
nixnax	226:4898247048c7	157	<h1>mbed PPP-Blinky WebSocket Test</h1>\
nixnax	226:4898247048c7	158	<h1><div id=\"sts\">Idle</div><h1>\
nixnax	226:4898247048c7	159	<button id=\"btn\">Connect</button>\
nixnax	142:54d1543e23e5	160	</body>\
nixnax	226:4898247048c7	161	</html>"; // size = 1037 bytes + 1 null byte = 1038 bytes
nixnax	142:54d1543e23e5	162
nixnax	142:54d1543e23e5	163	// 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	164	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	165	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	166	// See instructions at the top.
nixnax	142:54d1543e23e5	167	// 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	168	RawSerial pc (USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	169
nixnax	142:54d1543e23e5	170	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	171
nixnax	142:54d1543e23e5	172	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	173
nixnax	142:54d1543e23e5	174	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	175	void pppInitStruct()
nixnax	142:54d1543e23e5	176	{
nixnax	223:917b554cb8a5	177	memset( (void *)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	178	ppp.online=0;
nixnax	142:54d1543e23e5	179	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	180	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	181	ppp.rx.head=0;
nixnax	142:54d1543e23e5	182	ppp.rx.buflevel=0;
nixnax	209:aa514cd631ee	183	ppp.rx.maxbuflevel=0;
nixnax	221:1d7c32d8256b	184	ppp.rx.bufferfull=0;
nixnax	142:54d1543e23e5	185	ppp.pkt.len=0;
nixnax	154:18b2bd92f557	186	ppp.ipData.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	187	ppp.ledState=0;
nixnax	142:54d1543e23e5	188	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	189	ppp.responseCounter=0;
nixnax	239:426e50519204	190	ppp.pingCount=0; // number of ICMP pings we have received
nixnax	142:54d1543e23e5	191	ppp.firstFrame=1;
nixnax	175:b4e6f8a6fe00	192	ppp.ppp = (pppHeaderType *)ppp.pkt.buf; // pointer to ppp header
nixnax	175:b4e6f8a6fe00	193	ppp.ip = (ipHeaderType *)(ppp.pkt.buf+4); // pointer to IP header
nixnax	142:54d1543e23e5	194	}
nixnax	142:54d1543e23e5	195
nixnax	142:54d1543e23e5	196	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	197	void led1Toggle()
nixnax	142:54d1543e23e5	198	{
nixnax	142:54d1543e23e5	199	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	200	ppp.ledState++;
nixnax	142:54d1543e23e5	201	}
nixnax	142:54d1543e23e5	202
nixnax	179:ba2b2ddd0da5	203	/// Returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax	150:3366bf3d294e	204	int connectedPpp()
nixnax	142:54d1543e23e5	205	{
nixnax	142:54d1543e23e5	206	return ppp.online;
nixnax	143:c5019f856a56	207	}
nixnax	142:54d1543e23e5	208
nixnax	179:ba2b2ddd0da5	209	/// PPP serial port receive interrupt handler.
nixnax	143:c5019f856a56	210	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	211	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	179:ba2b2ddd0da5	212	void pppReceiveHandler()
nixnax	142:54d1543e23e5	213	{
nixnax	142:54d1543e23e5	214	char ch;
nixnax	179:ba2b2ddd0da5	215	while ( pc.readable() ) {
nixnax	223:917b554cb8a5	216	int localHead = (ppp.rx.head+1); // local head index
nixnax	223:917b554cb8a5	217	if (localHead > RXBUFLEN) localHead=0; // increment and wrap head index
nixnax	223:917b554cb8a5	218	if ( localHead == ppp.rx.rtail ) {
nixnax	221:1d7c32d8256b	219	ppp.rx.bufferfull = 1; // set flag if rx buffer is full
nixnax	252:b3c8c5699153	220	#define BUFFER_FULL_TRAP_YES
nixnax	243:24f899297799	221	#ifdef BUFFER_FULL_TRAP_YES
nixnax	243:24f899297799	222	while(1) {
nixnax	243:24f899297799	223	led1Toggle(); // flash LED at a slow rate to indicate buffer overfloe
nixnax	243:24f899297799	224	wait_ms(150);
nixnax	243:24f899297799	225	}
nixnax	252:b3c8c5699153	226	#else
nixnax	221:1d7c32d8256b	227	return; // don't read if rx buffer is full
nixnax	243:24f899297799	228	#endif
nixnax	142:54d1543e23e5	229	}
nixnax	142:54d1543e23e5	230	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	231	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	209:aa514cd631ee	232	if (ch == 0x7E) { // check for ppp frame start character
nixnax	209:aa514cd631ee	233	if ( ppp.online == 0 ) { // check if we are offline
nixnax	209:aa514cd631ee	234	ppp.online = 1; // if we see a frame start character we immediately change status to online
nixnax	142:54d1543e23e5	235	}
nixnax	142:54d1543e23e5	236	}
nixnax	223:917b554cb8a5	237	ppp.rx.head = localHead; // update real head pointer
nixnax	221:1d7c32d8256b	238	ppp.rx.buflevel++; // update buffer level counter
nixnax	209:aa514cd631ee	239	if ( ppp.rx.buflevel > ppp.rx.maxbuflevel ) {
nixnax	221:1d7c32d8256b	240	ppp.rx.maxbuflevel = ppp.rx.buflevel; // remember the maximum usage of rx buffer
nixnax	209:aa514cd631ee	241	}
nixnax	142:54d1543e23e5	242	}
nixnax	142:54d1543e23e5	243	}
nixnax	142:54d1543e23e5	244
nixnax	145:098b6ed2f7f2	245	/// update the cumulative PPP FCS (frame check sequence)
nixnax	226:4898247048c7	246	void fcsDo(register int x)
nixnax	142:54d1543e23e5	247	{
nixnax	230:ee097c486e45	248	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	249	x>>=1;
nixnax	230:ee097c486e45	250	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	251	x>>=1;
nixnax	230:ee097c486e45	252	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	253	x>>=1;
nixnax	230:ee097c486e45	254	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	255	x>>=1;
nixnax	230:ee097c486e45	256	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	257	x>>=1;
nixnax	230:ee097c486e45	258	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	259	x>>=1;
nixnax	230:ee097c486e45	260	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	220:54f45f924707	261	x>>=1;
nixnax	230:ee097c486e45	262	ppp.fcs=((ppp.fcs^x)&1) ? (ppp.fcs>>1)^0x8408 : ppp.fcs>>1;
nixnax	142:54d1543e23e5	263	}
nixnax	142:54d1543e23e5	264
nixnax	145:098b6ed2f7f2	265	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	266	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	267	{
nixnax	226:4898247048c7	268	ppp.fcs=0xffff; // fcs initial value
nixnax	145:098b6ed2f7f2	269	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	270	return ppp.fcs;
nixnax	142:54d1543e23e5	271	}
nixnax	142:54d1543e23e5	272
nixnax	142:54d1543e23e5	273	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	274	int pc_getBuf()
nixnax	142:54d1543e23e5	275	{
nixnax	142:54d1543e23e5	276	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	230:ee097c486e45	277	int temptail = ppp.rx.tail+1;
nixnax	230:ee097c486e45	278	if (temptail > RXBUFLEN) temptail=0;
nixnax	142:54d1543e23e5	279	ppp.rx.buflevel--;
nixnax	230:ee097c486e45	280	ppp.rx.tail = temptail;
nixnax	142:54d1543e23e5	281	return x;
nixnax	142:54d1543e23e5	282	}
nixnax	142:54d1543e23e5	283
nixnax	142:54d1543e23e5	284	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	285	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	286	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	164:c3de3d212c4b	287	/// In WireShark, use "Import Hex File". Import options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	288	void dumpPPPFrame()
nixnax	142:54d1543e23e5	289	{
nixnax	230:ee097c486e45	290	char pbuf[100];
nixnax	142:54d1543e23e5	291	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	210:a2a651249a9a	292
nixnax	142:54d1543e23e5	293	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	210:a2a651249a9a	294
nixnax	221:1d7c32d8256b	295	debugPuts(pbuf);
nixnax	142:54d1543e23e5	296	}
nixnax	210:a2a651249a9a	297
nixnax	142:54d1543e23e5	298	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	210:a2a651249a9a	299
nixnax	221:1d7c32d8256b	300	debugPuts(pbuf);
nixnax	142:54d1543e23e5	301	}
nixnax	142:54d1543e23e5	302
nixnax	142:54d1543e23e5	303	/// Process a received PPP frame
nixnax	142:54d1543e23e5	304	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	305	{
nixnax	226:4898247048c7	306	led1Toggle(); // change led1 state on received frames
nixnax	252:b3c8c5699153	307	ppp.pingCount++; // count any frame
nixnax	142:54d1543e23e5	308	if(start==end) {
nixnax	142:54d1543e23e5	309	return; // empty frame
nixnax	142:54d1543e23e5	310	}
nixnax	226:4898247048c7	311	ppp.fcs=0xffff; // fcs initial value
nixnax	142:54d1543e23e5	312	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	313	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	314	int unstuff=0;
nixnax	142:54d1543e23e5	315	int idx = start;
nixnax	142:54d1543e23e5	316	while(1) {
nixnax	142:54d1543e23e5	317	if (unstuff==0) {
nixnax	142:54d1543e23e5	318	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	319	else {
nixnax	142:54d1543e23e5	320	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	321	ppp.pkt.len++;
nixnax	142:54d1543e23e5	322	dest++;
nixnax	145:098b6ed2f7f2	323	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	324	}
nixnax	142:54d1543e23e5	325	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	326	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	327	ppp.pkt.len++;
nixnax	142:54d1543e23e5	328	dest++;
nixnax	145:098b6ed2f7f2	329	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	330	unstuff=0;
nixnax	142:54d1543e23e5	331	}
nixnax	216:e3c5a5b47295	332	idx = idx+1;
nixnax	216:e3c5a5b47295	333	if (idx > RXBUFLEN) idx=0;
nixnax	142:54d1543e23e5	334	if (idx == end) break;
nixnax	142:54d1543e23e5	335	}
nixnax	145:098b6ed2f7f2	336	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	226:4898247048c7	337	#ifdef DUMP_RECEIVED_PPP_FRAMES_YES
nixnax	226:4898247048c7	338	dumpPPPFrame(); // hex dump ALL ppp frames to the debug port
nixnax	226:4898247048c7	339	#endif
nixnax	142:54d1543e23e5	340	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	341	determinePacketType();
nixnax	142:54d1543e23e5	342	} else {
nixnax	142:54d1543e23e5	343	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	344	#ifdef REPORT_FCS_ERROR_YES
nixnax	230:ee097c486e45	345	char pbuf[100]; // local print buffer
nixnax	142:54d1543e23e5	346	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	221:1d7c32d8256b	347	debugPuts( pbuf );
nixnax	226:4898247048c7	348	#define DUMP_PPP_FRAME_ON_ERROR_NO
nixnax	226:4898247048c7	349	#ifdef DUMP_PPP_FRAME_ON_ERROR_YES
nixnax	226:4898247048c7	350	dumpPPPFrame(); // dump frames with errors in them
nixnax	226:4898247048c7	351	#endif
nixnax	142:54d1543e23e5	352	#endif
nixnax	142:54d1543e23e5	353	}
nixnax	142:54d1543e23e5	354	}
nixnax	142:54d1543e23e5	355
nixnax	142:54d1543e23e5	356	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	357	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	358	{
nixnax	247:7b0a8e6fbb86	359	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) \|\| (ch>0x7f) ) {
nixnax	226:4898247048c7	360	pc.putc(0x7d);
nixnax	226:4898247048c7	361	pc.putc(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	362	} else {
nixnax	226:4898247048c7	363	pc.putc(ch);
nixnax	142:54d1543e23e5	364	}
nixnax	142:54d1543e23e5	365	}
nixnax	142:54d1543e23e5	366
nixnax	142:54d1543e23e5	367	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	368	void sendPppFrame()
nixnax	143:c5019f856a56	369	{
nixnax	172:449dd7a28955	370	ppp.responseCounter++; // count the number of ppp frames we send
nixnax	145:098b6ed2f7f2	371	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	372	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	373	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	226:4898247048c7	374	pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	375	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	226:4898247048c7	376	// wait_us(86); // wait one character time
nixnax	210:a2a651249a9a	377
nixnax	142:54d1543e23e5	378	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	379	}
nixnax	226:4898247048c7	380	pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	381	}
nixnax	142:54d1543e23e5	382
nixnax	143:c5019f856a56	383	/// 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	384	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	385	{
nixnax	143:c5019f856a56	386	int result=0;
nixnax	143:c5019f856a56	387	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	388	return result;
nixnax	143:c5019f856a56	389	}
nixnax	143:c5019f856a56	390
nixnax	177:dab9e685af53	391	/// convert 4-byte ip address to 32-bit
nixnax	228:7fb878500862	392	unsigned int integersToIp( int a, int b, int c, int d)
nixnax	179:ba2b2ddd0da5	393	{
nixnax	177:dab9e685af53	394	return a<<24 \| b<<16 \| c<<8 \| d;
nixnax	177:dab9e685af53	395	}
nixnax	177:dab9e685af53	396
nixnax	142:54d1543e23e5	397	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	398	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	399	{
nixnax	230:ee097c486e45	400	debugPuts("Their IPCP Config Req, Our Ack\n");
nixnax	173:6774a0c851c4	401	if(ppp.ipcp->request[0]==3) {
nixnax	143:c5019f856a56	402	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	173:6774a0c851c4	403	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	404	}
nixnax	143:c5019f856a56	405
nixnax	167:ff8a2d8beeb1	406	ppp.ipcp->code=2; // change code to ack
nixnax	144:01d98cf7738e	407	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	408
nixnax	230:ee097c486e45	409	debugPuts("Our IPCP Ask (no options)\n");
nixnax	167:ff8a2d8beeb1	410	ppp.ipcp->code=1; // change code to request
nixnax	167:ff8a2d8beeb1	411	ppp.ipcp->lengthR = __REV16( 4 ); // 4 is minimum length - no options in this request
nixnax	167:ff8a2d8beeb1	412	ppp.pkt.len=4+4+2; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	413	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	414	}
nixnax	142:54d1543e23e5	415
nixnax	142:54d1543e23e5	416	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	417	void ipcpAckHandler()
nixnax	142:54d1543e23e5	418	{
nixnax	230:ee097c486e45	419	debugPuts("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	420	}
nixnax	142:54d1543e23e5	421
nixnax	143:c5019f856a56	422	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	423	/// 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	424	void ipcpNackHandler()
nixnax	142:54d1543e23e5	425	{
nixnax	230:ee097c486e45	426	debugPuts("Their IPCP Nack\n");
nixnax	173:6774a0c851c4	427	if (ppp.ipcp->request[0]==3) { // check if the NACK contains an IP address parameter
nixnax	167:ff8a2d8beeb1	428	ppp.ipcp->code=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	429	sendPppFrame(); // let's request this IP address as ours
nixnax	230:ee097c486e45	430	debugPuts("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	431	} else { // if it's not an IP nack we ignore it
nixnax	230:ee097c486e45	432	debugPuts("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	433	}
nixnax	142:54d1543e23e5	434	}
nixnax	142:54d1543e23e5	435
nixnax	142:54d1543e23e5	436	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	437	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	438	{
nixnax	230:ee097c486e45	439	debugPuts("Their IPCP Other\n");
nixnax	142:54d1543e23e5	440	}
nixnax	142:54d1543e23e5	441
nixnax	142:54d1543e23e5	442	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	443	void IPCPframe()
nixnax	142:54d1543e23e5	444	{
nixnax	167:ff8a2d8beeb1	445	int action = ppp.ipcp->code; // packet type is here
nixnax	167:ff8a2d8beeb1	446	switch (action) {
nixnax	142:54d1543e23e5	447	case 1:
nixnax	142:54d1543e23e5	448	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	449	break;
nixnax	142:54d1543e23e5	450	case 2:
nixnax	142:54d1543e23e5	451	ipcpAckHandler();
nixnax	142:54d1543e23e5	452	break;
nixnax	142:54d1543e23e5	453	case 3:
nixnax	142:54d1543e23e5	454	ipcpNackHandler();
nixnax	142:54d1543e23e5	455	break;
nixnax	142:54d1543e23e5	456	default:
nixnax	142:54d1543e23e5	457	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	458	}
nixnax	142:54d1543e23e5	459	}
nixnax	142:54d1543e23e5	460
nixnax	142:54d1543e23e5	461	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	161:d59f778bc8ab	462	unsigned int dataCheckSum(char * ptr, int len, int restart)
nixnax	142:54d1543e23e5	463	{
nixnax	159:4d1bf96a59cd	464	unsigned int i,hi,lo;
nixnax	142:54d1543e23e5	465	unsigned char placeHolder;
nixnax	161:d59f778bc8ab	466	if (restart) ppp.sum=0;
nixnax	142:54d1543e23e5	467	if (len&1) {
nixnax	142:54d1543e23e5	468	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	469	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	470	}
nixnax	142:54d1543e23e5	471	i=0;
nixnax	142:54d1543e23e5	472	while ( i<len ) {
nixnax	210:a2a651249a9a	473
nixnax	142:54d1543e23e5	474	hi = ptr[i++];
nixnax	142:54d1543e23e5	475	lo = ptr[i++];
nixnax	159:4d1bf96a59cd	476	ppp.sum = ppp.sum + ((hi<<8)\|lo);
nixnax	142:54d1543e23e5	477	}
nixnax	142:54d1543e23e5	478	if (len&1) {
nixnax	142:54d1543e23e5	479	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	480	}
nixnax	159:4d1bf96a59cd	481	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax	159:4d1bf96a59cd	482	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax	159:4d1bf96a59cd	483	return ~ppp.sum;
nixnax	142:54d1543e23e5	484	}
nixnax	142:54d1543e23e5	485
nixnax	142:54d1543e23e5	486	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	487	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	488	{
nixnax	161:d59f778bc8ab	489	ppp.ip->checksumR=0; // zero the checsum in the IP header
nixnax	161:d59f778bc8ab	490	int len = 4 * ppp.ip->headerLength; // length of IP header in bytes
nixnax	161:d59f778bc8ab	491	unsigned int sum = dataCheckSum(ppp.ipStart,len,1);
nixnax	161:d59f778bc8ab	492	ppp.ip->checksumR = __REV16( sum ); // insert fresh checksum
nixnax	146:a45f49a2b29c	493	}
nixnax	146:a45f49a2b29c	494
nixnax	147:0f40005cbc5f	495	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	496	void swapIpAddresses()
nixnax	147:0f40005cbc5f	497	{
nixnax	162:594729c0e5c1	498	unsigned int tempHold;
nixnax	162:594729c0e5c1	499	tempHold = ppp.ip->srcAdrR; // tempHold <- source IP
nixnax	162:594729c0e5c1	500	ppp.ip->srcAdrR = ppp.ip->dstAdrR; // source <- dest
nixnax	162:594729c0e5c1	501	ppp.ip->dstAdrR = tempHold; // dest <- tempHold*/
nixnax	147:0f40005cbc5f	502	}
nixnax	147:0f40005cbc5f	503
nixnax	149:969d98f6fb88	504	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	505	void swapIpPorts()
nixnax	149:969d98f6fb88	506	{
nixnax	173:6774a0c851c4	507	int headerSizeIP = 4 * (ppp.ip->headerLength); // calculate size of IP header
nixnax	173:6774a0c851c4	508	char * ipSrcPort = ppp.ipStart + headerSizeIP + 0; // ip source port location
nixnax	173:6774a0c851c4	509	char * ipDstPort = ppp.ipStart + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	510	char tempHold[2];
nixnax	149:969d98f6fb88	511	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	512	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	513	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	514	}
nixnax	149:969d98f6fb88	515
nixnax	170:3d3b2126181c	516	/// Build the "pseudo header" required for UDP and TCP, then calculate its checksum
nixnax	170:3d3b2126181c	517	void checkSumPseudoHeader( unsigned int packetLength )
nixnax	170:3d3b2126181c	518	{
nixnax	170:3d3b2126181c	519	// 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	520	pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax	170:3d3b2126181c	521	pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax	170:3d3b2126181c	522	pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax	170:3d3b2126181c	523	pseudoHeader.zero = 0; // zero byte
nixnax	170:3d3b2126181c	524	pseudoHeader.protocol = ppp.ip->protocol; // protocol number (udp or tcp)
nixnax	170:3d3b2126181c	525	pseudoHeader.lengthR = __REV16( packetLength ); // size of tcp or udp packet
nixnax	170:3d3b2126181c	526	dataCheckSum(pseudoHeader.start, 12, 1); // calculate this header's checksum
nixnax	170:3d3b2126181c	527	}
nixnax	170:3d3b2126181c	528
nixnax	171:46b36d4edd1d	529	/// initialize an IP packet to send
nixnax	171:46b36d4edd1d	530	void initIP (unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, unsigned int protocol)
nixnax	171:46b36d4edd1d	531	{
nixnax	171:46b36d4edd1d	532	ppp.ppp->address = 0xff;
nixnax	171:46b36d4edd1d	533	ppp.ppp->control = 3;
nixnax	171:46b36d4edd1d	534	ppp.ppp->protocolR = __REV16( 0x0021 );
nixnax	171:46b36d4edd1d	535	ppp.ip->version = 4;
nixnax	171:46b36d4edd1d	536	ppp.ip->headerLength = 5; // 5 words = 20 bytes
nixnax	171:46b36d4edd1d	537	ppp.ip->identR = __REV16(ppp.ipData.ident++); // insert our ident
nixnax	171:46b36d4edd1d	538	ppp.ip->dontFragment=1;
nixnax	171:46b36d4edd1d	539	ppp.ip->ttl=128;
nixnax	171:46b36d4edd1d	540	ppp.ip->protocol = protocol; // udp
nixnax	171:46b36d4edd1d	541	ppp.ip->srcAdrR = __REV(srcIp);
nixnax	171:46b36d4edd1d	542	ppp.ip->dstAdrR = __REV(dstIp);
nixnax	171:46b36d4edd1d	543	ppp.udpStart = ppp.ipStart + 20; // calculate start of udp header
nixnax	171:46b36d4edd1d	544	ppp.udp->srcPortR = __REV16(srcPort); // source port
nixnax	171:46b36d4edd1d	545	ppp.udp->dstPortR = __REV16(dstPort); // dest port
nixnax	171:46b36d4edd1d	546	}
nixnax	171:46b36d4edd1d	547
nixnax	171:46b36d4edd1d	548
nixnax	171:46b36d4edd1d	549	/// Build a UDP packet from scratch
nixnax	171:46b36d4edd1d	550	void sendUdp(unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, char * message,int msgLen)
nixnax	171:46b36d4edd1d	551	{
nixnax	171:46b36d4edd1d	552	struct {
nixnax	171:46b36d4edd1d	553	unsigned int ipAll; // length of entire ip packet
nixnax	171:46b36d4edd1d	554	unsigned int ipHeader; // length of ip header
nixnax	171:46b36d4edd1d	555	unsigned int udpAll; // length of entire udp packet
nixnax	171:46b36d4edd1d	556	unsigned int udpData; // length of udp data segment
nixnax	171:46b36d4edd1d	557	} len;
nixnax	171:46b36d4edd1d	558	len.ipHeader = 20; // ip header length
nixnax	171:46b36d4edd1d	559	len.udpData = msgLen; // udp data size
nixnax	171:46b36d4edd1d	560	len.udpAll = len.udpData+8; // update local udp packet length
nixnax	171:46b36d4edd1d	561	len.ipAll = len.ipHeader + len.udpAll; // update IP Length
nixnax	171:46b36d4edd1d	562	initIP(srcIp, dstIp, srcPort, dstPort, 17); // init a UDP packet
nixnax	171:46b36d4edd1d	563	ppp.ip->lengthR = __REV16(len.ipAll); // update IP length in buffer
nixnax	171:46b36d4edd1d	564	ppp.udpStart = ppp.ipStart + len.ipHeader; // calculate start of udp header
nixnax	171:46b36d4edd1d	565	memcpy( ppp.udp->data, message, len.udpData ); // copy the message to the buffer
nixnax	171:46b36d4edd1d	566	ppp.udp->lengthR = __REV16(len.udpAll); // update UDP length in buffer
nixnax	171:46b36d4edd1d	567	ppp.pkt.len = len.ipAll+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	568	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	569	checkSumPseudoHeader( len.udpAll ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	570	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	571	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,len.udpAll, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	572	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	573	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	574	}
nixnax	171:46b36d4edd1d	575
nixnax	146:a45f49a2b29c	576	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	577	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	578	void UDPpacket()
nixnax	146:a45f49a2b29c	579	{
nixnax	163:d1b4328e9f08	580	struct {
nixnax	163:d1b4328e9f08	581	unsigned int all; // length of entire ip packet
nixnax	163:d1b4328e9f08	582	unsigned int header; // length of ip header
nixnax	163:d1b4328e9f08	583	} ipLength;
nixnax	163:d1b4328e9f08	584
nixnax	163:d1b4328e9f08	585	struct {
nixnax	165:c47826d07e0d	586	unsigned int all; // length of entire udp packet
nixnax	163:d1b4328e9f08	587	unsigned int data; // length of udp data segment
nixnax	163:d1b4328e9f08	588	} udpLength;
nixnax	163:d1b4328e9f08	589
nixnax	163:d1b4328e9f08	590	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	163:d1b4328e9f08	591	ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	171:46b36d4edd1d	592	udpLength.all = __REV16( ppp.udp->lengthR ); // size of udp packet
nixnax	163:d1b4328e9f08	593	udpLength.data = udpLength.all - 8; // size of udp data
nixnax	147:0f40005cbc5f	594
nixnax	146:a45f49a2b29c	595	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	171:46b36d4edd1d	596	char * srcIP = ppp.ip->srcAdrPtr; // IP source
nixnax	171:46b36d4edd1d	597	char * dstIP = ppp.ip->dstAdrPtr; //IP destination
nixnax	163:d1b4328e9f08	598
nixnax	171:46b36d4edd1d	599	unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); // integer of UDP source port
nixnax	171:46b36d4edd1d	600	unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); // integer of UDP dest port
nixnax	163:d1b4328e9f08	601
nixnax	163:d1b4328e9f08	602	if(v0) {
nixnax	163:d1b4328e9f08	603	debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
nixnax	163:d1b4328e9f08	604	debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
nixnax	163:d1b4328e9f08	605	debugPrintf("Len %03d", udpLength);
nixnax	163:d1b4328e9f08	606	}
nixnax	146:a45f49a2b29c	607	if (v1) {
nixnax	163:d1b4328e9f08	608	int printSize = udpLength.data;
nixnax	146:a45f49a2b29c	609	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	610	for (int i=0; i<printSize; i++) {
nixnax	163:d1b4328e9f08	611	char ch = ppp.udp->data[i];
nixnax	146:a45f49a2b29c	612	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	613	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	614	} else {
nixnax	230:ee097c486e45	615	debugPuts("_");
nixnax	146:a45f49a2b29c	616	}
nixnax	146:a45f49a2b29c	617	}
nixnax	146:a45f49a2b29c	618	}
nixnax	230:ee097c486e45	619	if (v0) debugPuts("\n");
nixnax	146:a45f49a2b29c	620	#endif
nixnax	163:d1b4328e9f08	621	int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
nixnax	163:d1b4328e9f08	622	int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	623	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	146:a45f49a2b29c	624	if (echoFound) {
nixnax	171:46b36d4edd1d	625	swapIpAddresses(); // swap IP source and destination
nixnax	171:46b36d4edd1d	626	swapIpPorts(); // swap IP source and destination ports
nixnax	163:d1b4328e9f08	627	memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	170:3d3b2126181c	628	int n=0;
nixnax	230:ee097c486e45	629	#define IDENTIFY_UDP_SERVER_NO
nixnax	230:ee097c486e45	630	#ifdef IDENTIFY_UDP_SERVER_YES
nixnax	170:3d3b2126181c	631	n=n+sprintf(n+ppp.udp->data+udpLength.data, "} UDP Server: PPP-Blinky\n"); // an appendix
nixnax	230:ee097c486e45	632	#endif
nixnax	168:c77eb908042a	633	udpLength.data = udpLength.data + n; // update udp data size with the size of the appendix
nixnax	171:46b36d4edd1d	634	// we may have changed data length, update all the lengths
nixnax	171:46b36d4edd1d	635	udpLength.all = udpLength.data+8; // update local udp packet length
nixnax	171:46b36d4edd1d	636	ipLength.all = ipLength.header + udpLength.all; // update IP Length
nixnax	171:46b36d4edd1d	637	ppp.ip->lengthR = __REV16(ipLength.all); // update IP length in buffer
nixnax	171:46b36d4edd1d	638	ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
nixnax	171:46b36d4edd1d	639	ppp.pkt.len = ipLength.all+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	640	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	641	checkSumPseudoHeader( udpLength.all ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	642	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	643	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,udpLength.all, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	644	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	645	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	646	} else if ( testFound ) {
nixnax	171:46b36d4edd1d	647	unsigned int sI = __REV( ppp.ip->srcAdrR );
nixnax	171:46b36d4edd1d	648	unsigned int dI = __REV( ppp.ip->dstAdrR );
nixnax	171:46b36d4edd1d	649	unsigned int sp = __REV16( ppp.udp->srcPortR );
nixnax	171:46b36d4edd1d	650	unsigned int dp = __REV16( ppp.udp->dstPortR );
nixnax	172:449dd7a28955	651	int n=sprintf(ppp.pkt.buf+200,"Response Count %d\n", ppp.responseCounter);
nixnax	171:46b36d4edd1d	652	sendUdp(dI,sI,dp,sp,ppp.pkt.buf+200,n); // build a udp packet from the ground up
nixnax	146:a45f49a2b29c	653	}
nixnax	146:a45f49a2b29c	654	}
nixnax	142:54d1543e23e5	655	}
nixnax	142:54d1543e23e5	656
nixnax	174:e5a3f16421a5	657	/// UDP demo that sends a udp packet containing a character received from the second debug serial port.
nixnax	174:e5a3f16421a5	658	/// Sends a 48 byte IP/UDP header for every 1 byte of data so line-mode would probably be better.
nixnax	178:3f17aa0ce5ce	659	/// If you want ip packets from ppp blinky to be routed to other networks, ensure you have ip routing enabled.
nixnax	178:3f17aa0ce5ce	660	/// See http://www.wikihow.com/Enable-IP-Routing.
nixnax	179:ba2b2ddd0da5	661	/// Also ensure that the firewall on the receiving machine has the receiving UDP port (12345 in this example) enabled.
nixnax	179:ba2b2ddd0da5	662	/// The netcat UDP receive command on the remote host would be: nc -ul 12345
nixnax	174:e5a3f16421a5	663	void sendUdpData()
nixnax	174:e5a3f16421a5	664	{
nixnax	174:e5a3f16421a5	665	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	179:ba2b2ddd0da5	666	if (ppp.online) {
nixnax	179:ba2b2ddd0da5	667	if (xx.readable()) {
nixnax	179:ba2b2ddd0da5	668	char inchar = xx.getc();
nixnax	179:ba2b2ddd0da5	669	xx.putc( inchar ); // echo the received character on the debug serial port
nixnax	228:7fb878500862	670	sendUdp(integersToIp(172,10,10,2), integersToIp(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	671	}
nixnax	174:e5a3f16421a5	672	}
nixnax	174:e5a3f16421a5	673	#endif
nixnax	174:e5a3f16421a5	674	}
nixnax	174:e5a3f16421a5	675
nixnax	142:54d1543e23e5	676	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	677	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	678	{
nixnax	165:c47826d07e0d	679	struct {
nixnax	165:c47826d07e0d	680	unsigned int all; // length of entire ip packet
nixnax	165:c47826d07e0d	681	unsigned int header; // length of ip header
nixnax	165:c47826d07e0d	682	} ipLength;
nixnax	165:c47826d07e0d	683	struct {
nixnax	165:c47826d07e0d	684	unsigned int all; // length of entire udp packet
nixnax	165:c47826d07e0d	685	unsigned int data; // length of udp data segment
nixnax	165:c47826d07e0d	686	} icmpLength;
nixnax	165:c47826d07e0d	687	ipLength.all = __REV16( ppp.ip->lengthR ); // length of ip packet
nixnax	165:c47826d07e0d	688	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	165:c47826d07e0d	689	ppp.icmpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	165:c47826d07e0d	690	icmpLength.all = ipLength.all - ipLength.header; // length of icmp packet
nixnax	165:c47826d07e0d	691	icmpLength.data = icmpLength.all - 8; // length of icmp data
nixnax	142:54d1543e23e5	692	#define ICMP_TYPE_PING_REQUEST 8
nixnax	165:c47826d07e0d	693	if ( ppp.icmp->type == ICMP_TYPE_PING_REQUEST ) {
nixnax	165:c47826d07e0d	694	ppp.ip->ttl--; // decrement time to live (so we have to update header checksum)
nixnax	253:ee1044976b2c	695	//ppp.pingCount++; // count how many times we get pinged
nixnax	147:0f40005cbc5f	696	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	167:ff8a2d8beeb1	697	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	698	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	165:c47826d07e0d	699	int icmpIdent = __REV16( ppp.ip->identR ); // byte reversed - big endian
nixnax	165:c47826d07e0d	700	int icmpSequence = __REV16( ppp.icmp->sequenceR ); // byte reversed - big endian
nixnax	142:54d1543e23e5	701	if(1) {
nixnax	230:ee097c486e45	702	char pbuf[100];
nixnax	210:a2a651249a9a	703
nixnax	142:54d1543e23e5	704	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	705	debugPuts( pbuf );
nixnax	210:a2a651249a9a	706
nixnax	142:54d1543e23e5	707	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	210:a2a651249a9a	708
nixnax	221:1d7c32d8256b	709	debugPuts( pbuf );
nixnax	142:54d1543e23e5	710	}
nixnax	142:54d1543e23e5	711	#endif
nixnax	147:0f40005cbc5f	712	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	713	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	714	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	165:c47826d07e0d	715	ppp.icmp->type = ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	165:c47826d07e0d	716	ppp.icmp->checkSumR = 0; // zero the checksum for recalculation
nixnax	165:c47826d07e0d	717	unsigned int sum = dataCheckSum(ppp.icmpStart, icmpLength.all, 1); // icmp checksum
nixnax	165:c47826d07e0d	718	ppp.icmp->checkSumR = __REV16( sum ); // save big-endian icmp checksum
nixnax	226:4898247048c7	719	#define DUMP_ICMP_PACKETS_NO
nixnax	226:4898247048c7	720	#ifdef DUMP_ICMP_PACKETS_YES
nixnax	165:c47826d07e0d	721	int printSize = icmpLength.data; // exclude size of icmp header
nixnax	142:54d1543e23e5	722	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	226:4898247048c7	723	for (int i=0; i<printSize; i++) {
nixnax	226:4898247048c7	724	char ch = ppp.icmp->data[i];
nixnax	226:4898247048c7	725	if (ch>31 && ch<127) {
nixnax	226:4898247048c7	726	debugPutc(ch);
nixnax	226:4898247048c7	727	} else {
nixnax	226:4898247048c7	728	debugPutc('_'); // for non-printable characters
nixnax	142:54d1543e23e5	729	}
nixnax	142:54d1543e23e5	730	}
nixnax	226:4898247048c7	731	debugPutc('\n');
nixnax	226:4898247048c7	732	#endif
nixnax	144:01d98cf7738e	733	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	734	} else {
nixnax	142:54d1543e23e5	735	if (v0) {
nixnax	165:c47826d07e0d	736	debugPrintf("ICMP type=%x \n", ppp.icmp->type);
nixnax	142:54d1543e23e5	737	}
nixnax	142:54d1543e23e5	738	}
nixnax	142:54d1543e23e5	739	}
nixnax	142:54d1543e23e5	740
nixnax	142:54d1543e23e5	741	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	742	void IGMPpacket()
nixnax	142:54d1543e23e5	743	{
nixnax	142:54d1543e23e5	744	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	745	}
nixnax	142:54d1543e23e5	746
nixnax	142:54d1543e23e5	747	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	748	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	749	{
nixnax	142:54d1543e23e5	750	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	210:a2a651249a9a	751
nixnax	155:9c6a1d249e26	752	int IPv4Id = __REV16(ppp.ip->identR);
nixnax	230:ee097c486e45	753	char pbuf[100]; // local print buffer
nixnax	142:54d1543e23e5	754	int n=0;
nixnax	142:54d1543e23e5	755	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	756	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	757	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	758	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	167:ff8a2d8beeb1	759	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	760	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	142:54d1543e23e5	761	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	762	#endif
nixnax	221:1d7c32d8256b	763	debugPuts( pbuf );
nixnax	142:54d1543e23e5	764	#ifndef TCP_HEADER_DUMP_YES
nixnax	221:1d7c32d8256b	765	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	766	#endif
nixnax	142:54d1543e23e5	767	#endif
nixnax	142:54d1543e23e5	768	}
nixnax	142:54d1543e23e5	769
nixnax	142:54d1543e23e5	770	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	771	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	772	{
nixnax	142:54d1543e23e5	773	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	155:9c6a1d249e26	774	char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	775	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	776	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	155:9c6a1d249e26	777	memset(flagString,'.', 8); // fill string with "........"
nixnax	156:163c23249731	778	if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax	156:163c23249731	779	if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax	156:163c23249731	780	if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax	156:163c23249731	781	if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax	156:163c23249731	782	if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax	156:163c23249731	783	if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax	156:163c23249731	784	if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax	156:163c23249731	785	if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax	155:9c6a1d249e26	786	flagString[8]=0; // null terminate string
nixnax	142:54d1543e23e5	787	#else
nixnax	156:163c23249731	788	if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax	156:163c23249731	789	if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax	156:163c23249731	790	if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax	156:163c23249731	791	if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax	156:163c23249731	792	if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax	155:9c6a1d249e26	793	flagString[1]=0; // null terminate string
nixnax	142:54d1543e23e5	794	#endif
nixnax	221:1d7c32d8256b	795	debugPuts( flagString );
nixnax	142:54d1543e23e5	796	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	797	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	221:1d7c32d8256b	798	debugPuts("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	160:bd701ad564cb	799	#else
nixnax	221:1d7c32d8256b	800	debugPuts("\x1b[30m"); // write a black color after every packet
nixnax	142:54d1543e23e5	801	#endif
nixnax	156:163c23249731	802	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	803	debugPutc('\n'); // insert an extra new line to mark the end (except for final ack) of an HTTP conversation
nixnax	142:54d1543e23e5	804	}
nixnax	142:54d1543e23e5	805	#endif
nixnax	142:54d1543e23e5	806	}
nixnax	142:54d1543e23e5	807
nixnax	143:c5019f856a56	808	/// Encode a buffer in base-64
nixnax	184:4133f557d4d4	809	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	810	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	811	{
nixnax	142:54d1543e23e5	812	int i,j,a,b,c;
nixnax	142:54d1543e23e5	813	i=0;
nixnax	142:54d1543e23e5	814	j=0;
nixnax	142:54d1543e23e5	815	while(1) {
nixnax	142:54d1543e23e5	816	if (i<len) {
nixnax	142:54d1543e23e5	817	a = in[i++];
nixnax	142:54d1543e23e5	818	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	819	} else break;
nixnax	142:54d1543e23e5	820	if (i<len) {
nixnax	142:54d1543e23e5	821	b = in[i++];
nixnax	142:54d1543e23e5	822	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	823	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	824	} else out[j++] = '=';
nixnax	142:54d1543e23e5	825	if (i<len) {
nixnax	142:54d1543e23e5	826	c = in[i++];
nixnax	142:54d1543e23e5	827	j--;
nixnax	142:54d1543e23e5	828	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	829	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	830	} else out[j++] = '=';
nixnax	142:54d1543e23e5	831	}
nixnax	142:54d1543e23e5	832	out[j]=0;
nixnax	142:54d1543e23e5	833	}
nixnax	142:54d1543e23e5	834
nixnax	160:bd701ad564cb	835	/// Handle a request for an http websocket.
nixnax	160:bd701ad564cb	836	/// 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	837	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	838	{
nixnax	142:54d1543e23e5	839	int n=0; // byte counter
nixnax	184:4133f557d4d4	840	char * key = strstr(dataStart, "Sec-WebSocket-Key:"); // search for the key in the payload
nixnax	142:54d1543e23e5	841	if (key != NULL) {
nixnax	184:4133f557d4d4	842	key = key + 18; // skip over the key ident string "Sec-WebSocket-Key:"
nixnax	221:1d7c32d8256b	843	if (v0) debugPuts("WebSocket Request\n");
nixnax	184:4133f557d4d4	844	while ( strchr(lut, *key) == NULL) key++; // skip non-valid base-64 characters (whitespace)
nixnax	184:4133f557d4d4	845	char challenge [80];
nixnax	184:4133f557d4d4	846	int i=0;
nixnax	184:4133f557d4d4	847	char * copyTo = challenge;
nixnax	184:4133f557d4d4	848	while (strchr(lut, *key) != NULL) { // copy while we see valid base-64 characters
nixnax	184:4133f557d4d4	849	if (i++ >40) break; // prevent buffer overflow
nixnax	184:4133f557d4d4	850	copyTo++ = key++; // copy next valid base-64 character
nixnax	184:4133f557d4d4	851	}
nixnax	184:4133f557d4d4	852	strcpy(copyTo,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"); // append websocket gui code
nixnax	226:4898247048c7	853	#define DUMP_WEBSOCKET_CHALLENGE_NO
nixnax	226:4898247048c7	854	#ifdef DUMP_WEBSOCKET_CHALLENGE_YES
nixnax	226:4898247048c7	855	debugPrintf("Challenge is %s\n", challenge); // the string we hash for the challenge
nixnax	227:f87156f9ef11	856	#endif
nixnax	142:54d1543e23e5	857	char shaOutput [20]; // sha1 output
nixnax	184:4133f557d4d4	858	sha1( shaOutput, challenge, strlen(challenge)); // hash the challenge
nixnax	142:54d1543e23e5	859	char encOut[50];
nixnax	184:4133f557d4d4	860	enc64( shaOutput, encOut, 20); // base-64 encode
nixnax	142:54d1543e23e5	861	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	862	char * version = challenge;
nixnax	184:4133f557d4d4	863	strncpy(version, versionstring,70); // copy their version string
nixnax	142:54d1543e23e5	864	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	240:d7a01533397d	865	memset(dataStart,0,500); // blank out old data before sending the websocket response header
nixnax	142:54d1543e23e5	866	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	867	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	868	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	869	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	870	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	871	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	872	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	873	}
nixnax	142:54d1543e23e5	874	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	875	}
nixnax	142:54d1543e23e5	876
nixnax	142:54d1543e23e5	877	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	878	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	879	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	880	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	881	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	882
nixnax	142:54d1543e23e5	883	/// respond to an HTTP request
nixnax	185:4cd8f91e9d49	884	int httpResponse(char * dataStart, int * flags)
nixnax	142:54d1543e23e5	885	{
nixnax	142:54d1543e23e5	886	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	887	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	160:bd701ad564cb	888	if (n>0) return n; // if n>0 we already have a response, so return
nixnax	142:54d1543e23e5	889
nixnax	142:54d1543e23e5	890	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	891	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	892	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	185:4cd8f91e9d49	893	*flags = TCP_FLAG_ACK \| TCP_FLAG_FIN; // the default case is that we close the connection
nixnax	142:54d1543e23e5	894
nixnax	142:54d1543e23e5	895	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	896	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	897	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	898	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	899	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	210:a2a651249a9a	900	if( (httpGetRoot==0) \|\| (httpGetx==0) \|\| (httpGet5 == 'w') ) {
nixnax	229:a81c37376187	901	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed PPP-Blinky\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	902	} else {
nixnax	229:a81c37376187	903	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	904	}
nixnax	142:54d1543e23e5	905	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	906	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	907	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	250:35a3a19dc184	908	//n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	217:86498f9ab967	909	#define SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	910	#ifdef SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	911	// 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	912	n=n+sprintf(n+dataStart,"Maxbuflevel: %d\r\n", ppp.rx.maxbuflevel);
nixnax	210:a2a651249a9a	913	#endif
nixnax	241:dece92cb7296	914	#define SHOWPINGCOUNT_NO
nixnax	240:d7a01533397d	915	#ifdef SHOWPINGCOUNT_YES
nixnax	241:dece92cb7296	916	// if this is enabled then the ICMP ping count will show up in the http headers of your browser - disabled for now because it's also displayed in the root page
nixnax	240:d7a01533397d	917	n=n+sprintf(n+dataStart,"PingCount: %d\r\n", ppp.pingCount);
nixnax	240:d7a01533397d	918	#endif
nixnax	142:54d1543e23e5	919	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	920	nHeader=n; // size of HTTP header
nixnax	210:a2a651249a9a	921
nixnax	142:54d1543e23e5	922	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	923	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	924	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	925	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	241:dece92cb7296	926	// naximum length of pingCount (maximum number of digits of an unsigned 32-bit int)
nixnax	241:dece92cb7296	927	#define PINGCOUNTMAXLEN (10)
nixnax	241:dece92cb7296	928	char pingCountString[PINGCOUNTMAXLEN+1]; // space for the ten digits and a string terminator 0
nixnax	241:dece92cb7296	929	snprintf(pingCountString,PINGCOUNTMAXLEN+1,"%*d",PINGCOUNTMAXLEN,ppp.pingCount); // print number of ICMP pings right justified in 10 spaces
nixnax	241:dece92cb7296	930	char * pingCountStart = strstr(dataStart,"0000000000"); // find the ten zeros in the page - this is where we must paste in the ICMP count
nixnax	241:dece92cb7296	931	if ( pingCountStart != NULL )
nixnax	241:dece92cb7296	932	memcpy(pingCountStart, pingCountString, PINGCOUNTMAXLEN); // copy ping count over the ten zeros in the page
nixnax	210:a2a651249a9a	933	} else if ( httpGet5 == 'w' ) { // "w" is a special page for websocket demo
nixnax	142:54d1543e23e5	934	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	935	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	185:4cd8f91e9d49	936	*flags = TCP_FLAG_ACK \| TCP_FLAG_PSH; // for a websocket page we do NOT close the connection
nixnax	142:54d1543e23e5	937	} else {
nixnax	142:54d1543e23e5	938	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	939	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	940	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	941	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	942	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	248:5aca1c98fc24	943	#endif
nixnax	249:9ff0e20325f7	944	if( (ppp.pingCount & 1) == 0) // check lowest bit of ping counter and respond with red or green favicon - this stops browsers from asking for favicon.ico file
nixnax	249:9ff0e20325f7	945	n=n+sprintf(n+dataStart,"<link rel=\"icon\" id=\"red-pixel\" href=\"data:image/gif;base64,R0lGODlhAQABAIABAP8AAAAAACwAAAAAAQABAAACAkQBADs\">"); // data url containing 1 red pixel gif
nixnax	248:5aca1c98fc24	946	else
nixnax	249:9ff0e20325f7	947	n=n+sprintf(n+dataStart,"<link rel=\"icon\" id=\"grn-pixel\" href=\"data:image/gif;base64,R0lGODlhAQABAIABAAD/AAAAACwAAAAAAQABAAACAkQBADs=\">"); // data url containing 1 green pixel gif
nixnax	248:5aca1c98fc24	948	if( httpGet6 == 'b' ) // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	248:5aca1c98fc24	949	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	248:5aca1c98fc24	950	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	248:5aca1c98fc24	951	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	146:a45f49a2b29c	952	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	248:5aca1c98fc24	953	#else
nixnax	146:a45f49a2b29c	954	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	955	#endif
nixnax	248:5aca1c98fc24	956	}
nixnax	248:5aca1c98fc24	957	else {
nixnax	249:9ff0e20325f7	958	// all other requests get a Mot Found response
nixnax	142:54d1543e23e5	959	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	960	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	961	}
nixnax	142:54d1543e23e5	962	}
nixnax	142:54d1543e23e5	963	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	964	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	965	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	966	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	967	return n; // total byte size of our response
nixnax	142:54d1543e23e5	968	}
nixnax	142:54d1543e23e5	969
nixnax	160:bd701ad564cb	970	/// Handle TCP data that is not an HTTP GET.
nixnax	160:bd701ad564cb	971	/// This is handy when for example you want to use netcat (nc.exe) to talk to PPP-Blinky.
nixnax	160:bd701ad564cb	972	/// This could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	973	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	974	{
nixnax	142:54d1543e23e5	975	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	976	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	160:bd701ad564cb	977	char mask [4];
nixnax	160:bd701ad564cb	978	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	160:bd701ad564cb	979	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	160:bd701ad564cb	980	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	981	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	982	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	983	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	160:bd701ad564cb	984	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	985	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	986	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	987	dataStart[1]=0; // we don't have mask bytes on
nixnax	160:bd701ad564cb	988	} else {
nixnax	184:4133f557d4d4	989	if ( len > 1 ) { // we assume a length of 1 is a keep-alive or push packet
nixnax	221:1d7c32d8256b	990	if (v1) debugPuts("TCP data received\n"); // all other tcp push packets
nixnax	184:4133f557d4d4	991	}
nixnax	163:d1b4328e9f08	992	}
nixnax	142:54d1543e23e5	993	return n; // total byte size of our response
nixnax	142:54d1543e23e5	994	}
nixnax	142:54d1543e23e5	995
nixnax	173:6774a0c851c4	996	/// dump the TCP data to the debug serial port
nixnax	173:6774a0c851c4	997	void dumpDataTCP(int outGoing)
nixnax	173:6774a0c851c4	998	{
nixnax	173:6774a0c851c4	999	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	173:6774a0c851c4	1000	if (v2) {
nixnax	173:6774a0c851c4	1001	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	173:6774a0c851c4	1002	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	1003	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax	173:6774a0c851c4	1004	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	1005	ppp.tcpData = ppp.tcpStart + headerSizeTcp; // start of tcp data
nixnax	173:6774a0c851c4	1006	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	173:6774a0c851c4	1007	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	230:ee097c486e45	1008	char pbuf[100]; // local print buffer
nixnax	173:6774a0c851c4	1009	int n=0;
nixnax	210:a2a651249a9a	1010
nixnax	173:6774a0c851c4	1011	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	210:a2a651249a9a	1012
nixnax	173:6774a0c851c4	1013	n=n+sprintf(pbuf+n, "IP:%d ipHeader:%d tcpHeader:%d tcpData:%d\n", packetLengthIp, headerSizeIp, headerSizeTcp, tcpDataSize); // 1 for more verbose
nixnax	230:ee097c486e45	1014	if (n>95) debugPuts("n>pbuf overflow in dumpDataTCP()\n");
nixnax	210:a2a651249a9a	1015
nixnax	221:1d7c32d8256b	1016	debugPuts( pbuf );
nixnax	173:6774a0c851c4	1017	if (tcpDataSize > 0) {
nixnax	173:6774a0c851c4	1018	ppp.tcpData[tcpDataSize]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	221:1d7c32d8256b	1019	debugPuts( ppp.tcpData ); // print the tcp payload data
nixnax	221:1d7c32d8256b	1020	debugPuts("\n");
nixnax	173:6774a0c851c4	1021	}
nixnax	221:1d7c32d8256b	1022	debugPuts( "\x1b[30m" ); // VT100 color code, print black
nixnax	173:6774a0c851c4	1023	}
nixnax	173:6774a0c851c4	1024	#endif
nixnax	173:6774a0c851c4	1025	}
nixnax	173:6774a0c851c4	1026
nixnax	142:54d1543e23e5	1027	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1028	/// 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	1029	void tcpHandler()
nixnax	142:54d1543e23e5	1030	{
nixnax	154:18b2bd92f557	1031	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	154:18b2bd92f557	1032	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	1033	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate TCP header start
nixnax	154:18b2bd92f557	1034	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	154:18b2bd92f557	1035	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	227:f87156f9ef11	1036	char * tcpDataIn = ppp.tcpStart + headerSizeTcp; // start of TCP data after TCP header
nixnax	154:18b2bd92f557	1037	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	154:18b2bd92f557	1038
nixnax	227:f87156f9ef11	1039	unsigned int seq_in = __REV(ppp.tcp->seqTcpR); // incoming sequence number
nixnax	227:f87156f9ef11	1040	unsigned int ack_in = __REV(ppp.tcp->ackTcpR); // incoming acknowledge number
nixnax	227:f87156f9ef11	1041	unsigned int ack_out = seq_in + tcpDataSize; // calculate the acknowledge based on size of received packet
nixnax	227:f87156f9ef11	1042	unsigned int seq_out = ack_in; // adopt their version of our sequence number as our sequence number
nixnax	142:54d1543e23e5	1043
nixnax	142:54d1543e23e5	1044	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	173:6774a0c851c4	1045	headerSizeIp=20;
nixnax	173:6774a0c851c4	1046	ppp.ip->headerLength = headerSizeIp/4; // ip header is 20 bytes long
nixnax	173:6774a0c851c4	1047	ppp.ip->lengthR = __REV(40); // 20 ip header + 20 tcp header
nixnax	227:f87156f9ef11	1048	headerSizeTcp = 20; // shorten outgoing TCP header size to 20 bytes (no data)
nixnax	173:6774a0c851c4	1049	ppp.tcpStart = ppp.ipStart + headerSizeIp; // recalc TCP header start
nixnax	154:18b2bd92f557	1050	ppp.tcp->offset = (headerSizeTcp/4);
nixnax	173:6774a0c851c4	1051	char * tcpDataOut = ppp.tcpStart + headerSizeTcp; // start of outgoing data
nixnax	142:54d1543e23e5	1052
nixnax	142:54d1543e23e5	1053	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	1054	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	160:bd701ad564cb	1055
nixnax	185:4cd8f91e9d49	1056	ppp.tcp->windowR = __REV16( 1200 ); // set tcp window size to 1200 bytes
nixnax	142:54d1543e23e5	1057
nixnax	142:54d1543e23e5	1058	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	1059
nixnax	156:163c23249731	1060	switch ( ppp.tcp->flag.All ) {
nixnax	142:54d1543e23e5	1061	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1062	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1063	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1064	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1065	break;
nixnax	184:4133f557d4d4	1066	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1067	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	184:4133f557d4d4	1068	if ( (ppp.tcp->flag.All == TCP_FLAG_ACK) && (tcpDataSize == 0)) return; // handle zero-size ack messages by ignoring them
nixnax	142:54d1543e23e5	1069	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	237:796851817c26	1070	led1Toggle(); // toggle the LED one more time so we can visualize the HTTP GET
nixnax	179:ba2b2ddd0da5	1071	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // we have data, set the PSH flag
nixnax	185:4cd8f91e9d49	1072	dataLen = httpResponse(tcpDataOut, &flagsOut); // send an http response
nixnax	142:54d1543e23e5	1073	} else {
nixnax	158:841592aed956	1074	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax	179:ba2b2ddd0da5	1075	if (dataLen > 0) flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // if we have any data set the PSH flag
nixnax	142:54d1543e23e5	1076	}
nixnax	142:54d1543e23e5	1077	break;
nixnax	142:54d1543e23e5	1078	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1079	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1080	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1081	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1082	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1083	break;
nixnax	142:54d1543e23e5	1084	default:
nixnax	179:ba2b2ddd0da5	1085	return; // ignore all other packets
nixnax	142:54d1543e23e5	1086	} // switch
nixnax	142:54d1543e23e5	1087
nixnax	142:54d1543e23e5	1088	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1089	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1090	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1091	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1092
nixnax	158:841592aed956	1093	ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	158:841592aed956	1094	ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	160:bd701ad564cb	1095
nixnax	156:163c23249731	1096	ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1097
nixnax	159:4d1bf96a59cd	1098	// recalculate all the header sizes
nixnax	154:18b2bd92f557	1099	tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax	154:18b2bd92f557	1100	int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax	159:4d1bf96a59cd	1101	ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax	142:54d1543e23e5	1102	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	1103
nixnax	142:54d1543e23e5	1104	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1105	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	170:3d3b2126181c	1106	checkSumPseudoHeader( tcpSize ); // get the TCP pseudo-header checksum
nixnax	159:4d1bf96a59cd	1107	ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	161:d59f778bc8ab	1108	unsigned int pseudoHeaderSum=dataCheckSum(ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax	159:4d1bf96a59cd	1109	ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	160:bd701ad564cb	1110
nixnax	170:3d3b2126181c	1111	dumpHeaderIP(1); // dump outgoing IP header before sending the frame
nixnax	170:3d3b2126181c	1112	dumpHeaderTCP(1); // dump outgoing TCP header before sending the frame
nixnax	173:6774a0c851c4	1113	dumpDataTCP(1); // dump outgoing TCP data before sending the frame
nixnax	226:4898247048c7	1114	#define WAIT_BEFORE_IP_SEND_NO
nixnax	226:4898247048c7	1115	#ifdef WAIT_BEFORE_IP_SEND_YES
nixnax	226:4898247048c7	1116	wait_ms(45); // 45 ms delay before sending frame
nixnax	226:4898247048c7	1117	#endif
nixnax	144:01d98cf7738e	1118	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	226:4898247048c7	1119	#define DUMP_TRANSMITTED_PPP_NO
nixnax	226:4898247048c7	1120	#ifdef DUMP_TRANSMITTED_PPP_YES
nixnax	226:4898247048c7	1121	dumpPPPFrame(); // dump every transmitted ppp frame to debug port
nixnax	226:4898247048c7	1122	#endif
nixnax	142:54d1543e23e5	1123	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1124	}
nixnax	142:54d1543e23e5	1125
nixnax	142:54d1543e23e5	1126	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1127	void TCPpacket()
nixnax	142:54d1543e23e5	1128	{
nixnax	173:6774a0c851c4	1129	dumpHeaderIP(0); // dump incoming packet IP header
nixnax	173:6774a0c851c4	1130	dumpHeaderTCP(0); // dump incoming packet TCP header
nixnax	173:6774a0c851c4	1131	dumpDataTCP(0); // dump incoming packet data
nixnax	142:54d1543e23e5	1132	tcpHandler();
nixnax	142:54d1543e23e5	1133	}
nixnax	142:54d1543e23e5	1134
nixnax	142:54d1543e23e5	1135	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1136	void otherProtocol()
nixnax	142:54d1543e23e5	1137	{
nixnax	230:ee097c486e45	1138	debugPuts("Other IP protocol");
nixnax	142:54d1543e23e5	1139	}
nixnax	142:54d1543e23e5	1140
nixnax	142:54d1543e23e5	1141	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1142	void IPframe()
nixnax	142:54d1543e23e5	1143	{
nixnax	167:ff8a2d8beeb1	1144	int protocol = ppp.ip->protocol;
nixnax	142:54d1543e23e5	1145	switch (protocol) {
nixnax	142:54d1543e23e5	1146	case 1:
nixnax	142:54d1543e23e5	1147	ICMPpacket();
nixnax	142:54d1543e23e5	1148	break;
nixnax	142:54d1543e23e5	1149	case 2:
nixnax	142:54d1543e23e5	1150	IGMPpacket();
nixnax	142:54d1543e23e5	1151	break;
nixnax	142:54d1543e23e5	1152	case 17:
nixnax	142:54d1543e23e5	1153	UDPpacket();
nixnax	142:54d1543e23e5	1154	break;
nixnax	142:54d1543e23e5	1155	case 6:
nixnax	142:54d1543e23e5	1156	TCPpacket();
nixnax	142:54d1543e23e5	1157	break;
nixnax	142:54d1543e23e5	1158	default:
nixnax	142:54d1543e23e5	1159	otherProtocol();
nixnax	142:54d1543e23e5	1160	}
nixnax	142:54d1543e23e5	1161	}
nixnax	142:54d1543e23e5	1162
nixnax	227:f87156f9ef11	1163	/// process LCP packets
nixnax	142:54d1543e23e5	1164	void LCPframe()
nixnax	142:54d1543e23e5	1165	{
nixnax	253:ee1044976b2c	1166	//ppp.pingCount++; // count how many times we get LCP packets or get pinged
nixnax	175:b4e6f8a6fe00	1167	int code = ppp.lcp->code;
nixnax	142:54d1543e23e5	1168	switch (code) {
nixnax	227:f87156f9ef11	1169	case 1: // LCP configuration request
nixnax	231:6bd4523833a2	1170	debugPuts("LCP Config");
nixnax	227:f87156f9ef11	1171	if ( __REV16( ppp.lcp->lengthR ) == 4 ) {
nixnax	230:ee097c486e45	1172	debugPuts("LCP Ack\n");
nixnax	227:f87156f9ef11	1173	ppp.lcp->code=2; // acknowledge zero configuration request
nixnax	227:f87156f9ef11	1174	sendPppFrame();
nixnax	227:f87156f9ef11	1175	ppp.lcp->code=1; // request no options
nixnax	227:f87156f9ef11	1176	sendPppFrame();
nixnax	227:f87156f9ef11	1177	} else {
nixnax	230:ee097c486e45	1178	debugPuts("LCP request reject\n");
nixnax	227:f87156f9ef11	1179	ppp.lcp->code=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	227:f87156f9ef11	1180	sendPppFrame();
nixnax	227:f87156f9ef11	1181	}
nixnax	227:f87156f9ef11	1182	break;
nixnax	227:f87156f9ef11	1183	case 2: // LCP configuration acknowledge
nixnax	230:ee097c486e45	1184	debugPuts("LCP Ack\n"); // don't do anything, i.e. ignore
nixnax	227:f87156f9ef11	1185	break;
nixnax	227:f87156f9ef11	1186	case 5: // LCP end
nixnax	227:f87156f9ef11	1187	ppp.lcp->code=6; // acknowledge
nixnax	227:f87156f9ef11	1188	sendPppFrame(); // acknowledge
nixnax	227:f87156f9ef11	1189	ppp.online=0; // start hunting for connect string again
nixnax	227:f87156f9ef11	1190	pppInitStruct(); // flush the receive buffer
nixnax	230:ee097c486e45	1191	debugPuts("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1192	break; // end connection
nixnax	142:54d1543e23e5	1193	default:
nixnax	231:6bd4523833a2	1194	debugPuts("LCP Other\n");
nixnax	142:54d1543e23e5	1195	}
nixnax	142:54d1543e23e5	1196	}
nixnax	142:54d1543e23e5	1197
nixnax	142:54d1543e23e5	1198	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1199	void discardedFrame()
nixnax	142:54d1543e23e5	1200	{
nixnax	142:54d1543e23e5	1201	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	1202	}
nixnax	142:54d1543e23e5	1203
nixnax	142:54d1543e23e5	1204	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1205	void determinePacketType()
nixnax	142:54d1543e23e5	1206	{
nixnax	167:ff8a2d8beeb1	1207	if ( ppp.ppp->address != 0xff ) {
nixnax	231:6bd4523833a2	1208	debugPuts("Unexpected: PPP address != ff\n");
nixnax	142:54d1543e23e5	1209	return;
nixnax	142:54d1543e23e5	1210	}
nixnax	167:ff8a2d8beeb1	1211	if ( ppp.ppp->control != 3 ) {
nixnax	231:6bd4523833a2	1212	debugPuts("Unexpected: PPP control != 3\n");
nixnax	142:54d1543e23e5	1213	return;
nixnax	142:54d1543e23e5	1214	}
nixnax	167:ff8a2d8beeb1	1215	unsigned int protocol = __REV16( ppp.ppp->protocolR );
nixnax	167:ff8a2d8beeb1	1216	switch ( protocol ) {
nixnax	167:ff8a2d8beeb1	1217	case 0xc021:
nixnax	142:54d1543e23e5	1218	LCPframe();
nixnax	142:54d1543e23e5	1219	break; // link control
nixnax	167:ff8a2d8beeb1	1220	case 0x8021:
nixnax	142:54d1543e23e5	1221	IPCPframe();
nixnax	142:54d1543e23e5	1222	break; // IP control
nixnax	167:ff8a2d8beeb1	1223	case 0x0021:
nixnax	142:54d1543e23e5	1224	IPframe();
nixnax	142:54d1543e23e5	1225	break; // IP itself
nixnax	142:54d1543e23e5	1226	default:
nixnax	142:54d1543e23e5	1227	discardedFrame();
nixnax	142:54d1543e23e5	1228	}
nixnax	142:54d1543e23e5	1229	}
nixnax	142:54d1543e23e5	1230
nixnax	146:a45f49a2b29c	1231	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1232	void sniff()
nixnax	146:a45f49a2b29c	1233	{
nixnax	221:1d7c32d8256b	1234	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	1235	}
nixnax	146:a45f49a2b29c	1236
nixnax	142:54d1543e23e5	1237	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1238	void waitForPppFrame()
nixnax	142:54d1543e23e5	1239	{
nixnax	142:54d1543e23e5	1240	while(1) {
nixnax	142:54d1543e23e5	1241	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1242	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1243	int rx = pc_getBuf(); // get the character
nixnax	238:f39289ed5a2e	1244	if (rx==0x7e) { // check for frame start/end character 0x7e
nixnax	142:54d1543e23e5	1245	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1246	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1247	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	181:bcfe7fe2142d	1248	ppp.firstFrame=0; // clear first frame flag
nixnax	142:54d1543e23e5	1249	} else {
nixnax	142:54d1543e23e5	1250	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1251	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1252	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1253	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1254	break;
nixnax	142:54d1543e23e5	1255	}
nixnax	142:54d1543e23e5	1256	}
nixnax	142:54d1543e23e5	1257	}
nixnax	210:a2a651249a9a	1258	// change below to YES to enable the serial to UDP demo
nixnax	210:a2a651249a9a	1259	#define SERIAL_TO_UDP_NO
nixnax	210:a2a651249a9a	1260	#ifdef SERIAL_TO_UDP_YES
nixnax	210:a2a651249a9a	1261	sendUdpData(); // demo that sends characters received on the DEBUG serial port via UDP to another host
nixnax	210:a2a651249a9a	1262	#endif
nixnax	142:54d1543e23e5	1263	}
nixnax	142:54d1543e23e5	1264	}
nixnax	142:54d1543e23e5	1265
nixnax	209:aa514cd631ee	1266	/// 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	1267	// 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	1268	void waitForPcConnectString()
nixnax	142:54d1543e23e5	1269	{
nixnax	142:54d1543e23e5	1270	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1271	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1272	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1273	if (found1 != NULL) {
nixnax	230:ee097c486e45	1274	if (v0) debugPuts("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	208:73086736610a	1275	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	142:54d1543e23e5	1276	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1277	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1278	}
nixnax	142:54d1543e23e5	1279	}
nixnax	142:54d1543e23e5	1280	}
nixnax	142:54d1543e23e5	1281
nixnax	144:01d98cf7738e	1282	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1283	void initializePpp()
nixnax	142:54d1543e23e5	1284	{
nixnax	210:a2a651249a9a	1285	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	144:01d98cf7738e	1286	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	230:ee097c486e45	1287	debugPuts("\x1b[2J\x1b[H\x1b[30m"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax	184:4133f557d4d4	1288	wait_ms(200); // a brief wait so a human can see the reset event
nixnax	230:ee097c486e45	1289	debugPuts("mbed PPP-Blinky HTTP & WebSocket server ready :)\n");
nixnax	210:a2a651249a9a	1290	#endif
nixnax	179:ba2b2ddd0da5	1291	pppInitStruct(); // initialize all the variables/properties/buffers
nixnax	179:ba2b2ddd0da5	1292	pc.baud(115200); // pc serial port acting as a dial-up modem - for PPP traffic
nixnax	179:ba2b2ddd0da5	1293	pc.attach(&pppReceiveHandler, RawSerial::RxIrq); // set up serial port receive interrupt handler
nixnax	143:c5019f856a56	1294	}

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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.