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@193:48072570f41d, 2017-11-22 (annotated)

Committer:: nixnax
Date:: Wed Nov 22 20:38:57 2017 +0000
Revision:: 193:48072570f41d
Parent:: 185:4cd8f91e9d49
Child:: 194:5b23ebfb3626

Added FRDM-KW41Z board second serial port support (p9,p10)

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	142:54d1543e23e5	12	// Handy reading material
nixnax	142:54d1543e23e5	13	// https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax	142:54d1543e23e5	14	// https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax	142:54d1543e23e5	15	// http://atari.kensclassics.org/wcomlog.htm
nixnax	142:54d1543e23e5	16
nixnax	142:54d1543e23e5	17	// Handy tools
nixnax	142:54d1543e23e5	18	// https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax	142:54d1543e23e5	19	// https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax	142:54d1543e23e5	20	// http://pingtester.net/ - nice tool for high rate ping testing
nixnax	142:54d1543e23e5	21	// http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax	142:54d1543e23e5	22	// https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax	142:54d1543e23e5	23	// https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax	142:54d1543e23e5	24	// Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax	142:54d1543e23e5	25
nixnax	142:54d1543e23e5	26	// Connecting PPP-Blinky to Linux
nixnax	142:54d1543e23e5	27	// PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax	142:54d1543e23e5	28	// pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax	142:54d1543e23e5	29	// in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax	142:54d1543e23e5	30	// See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax	142:54d1543e23e5	31
nixnax	142:54d1543e23e5	32	// Special pages when PPP-Blinky is running
nixnax	142:54d1543e23e5	33	// 172.10.10.2 root page
nixnax	182:f039ec218c9f	34	// 172.10.10.2/x returns the number of ppp frames sent - this is handy for testing
nixnax	182:f039ec218c9f	35	// 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	36	// 172.10.10.2/ws a simple WebSocket demo
nixnax	182:f039ec218c9f	37	// http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle, showing cross-domain access
nixnax	142:54d1543e23e5	38
nixnax	142:54d1543e23e5	39	// Ok, enough talking, time to check out some code!!
nixnax	142:54d1543e23e5	40
nixnax	142:54d1543e23e5	41	#include "ppp-blinky.h"
nixnax	142:54d1543e23e5	42
nixnax	142:54d1543e23e5	43	// The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax	146:a45f49a2b29c	44	// Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor the debug output.
nixnax	142:54d1543e23e5	45	// Using the second serial port will slow down packet response time
nixnax	142:54d1543e23e5	46	// Note - the LPC11U24 does NOT have a second serial port
nixnax	146:a45f49a2b29c	47
nixnax	183:6d3ba874b267	48	#define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax	142:54d1543e23e5	49
nixnax	142:54d1543e23e5	50	// here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax	142:54d1543e23e5	51	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	52	#if defined(TARGET_LPC1768)
nixnax	179:ba2b2ddd0da5	53	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	54	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	179:ba2b2ddd0da5	55	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	142:54d1543e23e5	56	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	57	#error The LPC11U24 does not have a second serial port to use for debugging - change SERIAL_PORT_MONITOR_YES back to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	58	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	179:ba2b2ddd0da5	59	RawSerial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	193:48072570f41d	60	#elif defined(TARGET_KW41Z)
nixnax	193:48072570f41d	61	RawSerial xx(p9, p10); // Second serial port on FRDM-KW41Z board
nixnax	142:54d1543e23e5	62	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	63	// change the next line to YOUR target board's second serial port pin definition if it's not present - and if it works, please send it to me - thanks!!!
nixnax	179:ba2b2ddd0da5	64	RawSerial xx(p9, p10); // change this to YOUR board second serial port pin definition - and please send it to me if it works!!!
nixnax	142:54d1543e23e5	65	#else
nixnax	142:54d1543e23e5	66	#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	67	#endif
nixnax	179:ba2b2ddd0da5	68	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we can print debug messages */
nixnax	142:54d1543e23e5	69	#define debugPutc(x...) xx.putc(x)
nixnax	142:54d1543e23e5	70	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	71	#else
nixnax	142:54d1543e23e5	72	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	73	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	74	#define debugPutc(x...) {}
nixnax	142:54d1543e23e5	75	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	76	#endif
nixnax	142:54d1543e23e5	77
nixnax	142:54d1543e23e5	78	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	182:f039ec218c9f	79	#define v0 1
nixnax	142:54d1543e23e5	80	#define v1 0
nixnax	142:54d1543e23e5	81	#define v2 0
nixnax	182:f039ec218c9f	82	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	182:f039ec218c9f	83	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	84
nixnax	142:54d1543e23e5	85	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	86	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	87
nixnax	142:54d1543e23e5	88	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	89	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	90	<html>\
nixnax	142:54d1543e23e5	91	<head>\
nixnax	146:a45f49a2b29c	92	<title>mbed PPP-Blinky</title>\r\n\
nixnax	146:a45f49a2b29c	93	<script>\r\n\
nixnax	142:54d1543e23e5	94	window.onload=function(){\
nixnax	142:54d1543e23e5	95	setInterval(function(){function x(){return document.getElementById('w');};\
nixnax	146:a45f49a2b29c	96	x().textContent=parseInt(x().textContent)+1;},100);};\r\n\
nixnax	146:a45f49a2b29c	97	</script>\r\n\
nixnax	142:54d1543e23e5	98	</head>\
nixnax	142:54d1543e23e5	99	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	100	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	101	<h1 id=\"w\">0</h1>\
nixnax	142:54d1543e23e5	102	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	142:54d1543e23e5	103	<h1><a href=\"/ws\">WebSocket Demo</a></h1>\
nixnax	142:54d1543e23e5	104	<h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	105	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	142:54d1543e23e5	106	<h1><a href=\"http://jsfiddle.net/d26cyuh2/\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	107	</body>\
nixnax	146:a45f49a2b29c	108	</html>\r\n"; // size = 644 bytes plus 1 null byte = 645 bytes
nixnax	142:54d1543e23e5	109
nixnax	167:ff8a2d8beeb1	110	// this is a websocket demo html page we serve when GET /ws is requested
nixnax	142:54d1543e23e5	111	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	112	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	113	<html>\
nixnax	142:54d1543e23e5	114	<head>\
nixnax	142:54d1543e23e5	115	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	116	<script>\
nixnax	142:54d1543e23e5	117	window.onload=function(){\
nixnax	142:54d1543e23e5	118	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	119	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	120	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	121	var ctr=0;\
nixnax	142:54d1543e23e5	122	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	123	btn.onclick=function(){\
nixnax	142:54d1543e23e5	124	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	125	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	126	x.onopen=function(){\
nixnax	142:54d1543e23e5	127	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	128	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	129	};\
nixnax	142:54d1543e23e5	130	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	131	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	132	} else {\
nixnax	142:54d1543e23e5	133	x.send(ctr);\
nixnax	142:54d1543e23e5	134	ctr=ctr+1;\
nixnax	142:54d1543e23e5	135	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	136	}\
nixnax	142:54d1543e23e5	137	};\
nixnax	142:54d1543e23e5	138	};\
nixnax	142:54d1543e23e5	139	</script>\
nixnax	142:54d1543e23e5	140	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	141	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	142	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	143	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	144	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	145	</body>\
nixnax	142:54d1543e23e5	146	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	147
nixnax	142:54d1543e23e5	148	// The serial port on your mbed hardware. Your PC should be configured to view this port as a standard dial-up networking modem.
nixnax	142:54d1543e23e5	149	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	150	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	151	// See instructions at the top.
nixnax	142:54d1543e23e5	152	// On a typical mbed hardware platform this serial port is a USB virtual com port (VCP) and the USB serial driver is supplied by the board vendor.
nixnax	179:ba2b2ddd0da5	153	RawSerial pc (USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	154
nixnax	142:54d1543e23e5	155	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	156
nixnax	142:54d1543e23e5	157	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	158	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	159
nixnax	142:54d1543e23e5	160	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	161
nixnax	142:54d1543e23e5	162	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	163	void pppInitStruct()
nixnax	142:54d1543e23e5	164	{
nixnax	142:54d1543e23e5	165	memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax	142:54d1543e23e5	166	ppp.online=0;
nixnax	142:54d1543e23e5	167	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	168	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	169	ppp.rx.head=0;
nixnax	142:54d1543e23e5	170	ppp.rx.buflevel=0;
nixnax	142:54d1543e23e5	171	ppp.pkt.len=0;
nixnax	154:18b2bd92f557	172	ppp.ipData.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	173	ppp.ledState=0;
nixnax	142:54d1543e23e5	174	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	175	ppp.responseCounter=0;
nixnax	142:54d1543e23e5	176	ppp.firstFrame=1;
nixnax	175:b4e6f8a6fe00	177	ppp.ppp = (pppHeaderType *)ppp.pkt.buf; // pointer to ppp header
nixnax	175:b4e6f8a6fe00	178	ppp.ip = (ipHeaderType *)(ppp.pkt.buf+4); // pointer to IP header
nixnax	142:54d1543e23e5	179	}
nixnax	142:54d1543e23e5	180
nixnax	142:54d1543e23e5	181	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	182	void led1Toggle()
nixnax	142:54d1543e23e5	183	{
nixnax	142:54d1543e23e5	184	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	185	ppp.ledState++;
nixnax	142:54d1543e23e5	186	}
nixnax	142:54d1543e23e5	187
nixnax	179:ba2b2ddd0da5	188	/// Returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax	150:3366bf3d294e	189	int connectedPpp()
nixnax	142:54d1543e23e5	190	{
nixnax	142:54d1543e23e5	191	return ppp.online;
nixnax	143:c5019f856a56	192	}
nixnax	142:54d1543e23e5	193
nixnax	179:ba2b2ddd0da5	194	/// Previously used to check for characters in receive buffer.
nixnax	179:ba2b2ddd0da5	195	/// Now just a stub.
nixnax	179:ba2b2ddd0da5	196	void checkPc() {};
nixnax	179:ba2b2ddd0da5	197
nixnax	179:ba2b2ddd0da5	198	/// PPP serial port receive interrupt handler.
nixnax	143:c5019f856a56	199	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	200	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	179:ba2b2ddd0da5	201	void pppReceiveHandler()
nixnax	142:54d1543e23e5	202	{
nixnax	142:54d1543e23e5	203	char ch;
nixnax	179:ba2b2ddd0da5	204	while ( pc.readable() ) {
nixnax	142:54d1543e23e5	205	int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax	142:54d1543e23e5	206	if ( hd == ppp.rx.rtail ) {
nixnax	142:54d1543e23e5	207	debugPrintf("\nReceive buffer full\n");
nixnax	142:54d1543e23e5	208	return;
nixnax	142:54d1543e23e5	209	}
nixnax	142:54d1543e23e5	210	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	211	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	142:54d1543e23e5	212	if ( ppp.online == 0 ) {
nixnax	142:54d1543e23e5	213	if (ch == 0x7E) {
nixnax	142:54d1543e23e5	214	ppp.online = 1;
nixnax	142:54d1543e23e5	215	}
nixnax	142:54d1543e23e5	216	}
nixnax	142:54d1543e23e5	217	ppp.rx.head = hd; // update head pointer
nixnax	142:54d1543e23e5	218	ppp.rx.buflevel++;
nixnax	142:54d1543e23e5	219	}
nixnax	142:54d1543e23e5	220	}
nixnax	142:54d1543e23e5	221
nixnax	142:54d1543e23e5	222	/// print to debug port while checking for incoming characters
nixnax	142:54d1543e23e5	223	void putcWhileCheckingInput( char outByte )
nixnax	142:54d1543e23e5	224	{
nixnax	142:54d1543e23e5	225	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	226	checkPc();
nixnax	142:54d1543e23e5	227	debugPutc( outByte );
nixnax	142:54d1543e23e5	228	checkPc();
nixnax	142:54d1543e23e5	229	#endif
nixnax	142:54d1543e23e5	230	}
nixnax	142:54d1543e23e5	231
nixnax	142:54d1543e23e5	232	/// puts to debug port while checking the PPP input stream
nixnax	142:54d1543e23e5	233	void putsWhileCheckingInput( char * data )
nixnax	142:54d1543e23e5	234	{
nixnax	142:54d1543e23e5	235	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	236	char * nextChar = data;
nixnax	142:54d1543e23e5	237	while( *nextChar != 0 ) {
nixnax	142:54d1543e23e5	238	putcWhileCheckingInput( *nextChar ); // write one character to debug port while checking input
nixnax	142:54d1543e23e5	239	nextChar++;
nixnax	142:54d1543e23e5	240	}
nixnax	142:54d1543e23e5	241	#endif
nixnax	142:54d1543e23e5	242	}
nixnax	142:54d1543e23e5	243
nixnax	145:098b6ed2f7f2	244	/// Initialize the PPP FCS (frame check sequence) total
nixnax	145:098b6ed2f7f2	245	void fcsReset()
nixnax	142:54d1543e23e5	246	{
nixnax	145:098b6ed2f7f2	247	ppp.fcs=0xffff; // crc restart
nixnax	142:54d1543e23e5	248	}
nixnax	142:54d1543e23e5	249
nixnax	145:098b6ed2f7f2	250	/// update the cumulative PPP FCS (frame check sequence)
nixnax	145:098b6ed2f7f2	251	void fcsDo(int x)
nixnax	142:54d1543e23e5	252	{
nixnax	142:54d1543e23e5	253	for (int i=0; i<8; i++) {
nixnax	145:098b6ed2f7f2	254	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1; // crc calculator
nixnax	142:54d1543e23e5	255	x>>=1;
nixnax	142:54d1543e23e5	256	}
nixnax	142:54d1543e23e5	257	checkPc(); // handle input
nixnax	142:54d1543e23e5	258	}
nixnax	142:54d1543e23e5	259
nixnax	145:098b6ed2f7f2	260	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	261	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	262	{
nixnax	145:098b6ed2f7f2	263	fcsReset();
nixnax	145:098b6ed2f7f2	264	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	265	return ppp.fcs;
nixnax	142:54d1543e23e5	266	}
nixnax	142:54d1543e23e5	267
nixnax	142:54d1543e23e5	268	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	269	int pc_getBuf()
nixnax	142:54d1543e23e5	270	{
nixnax	142:54d1543e23e5	271	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	142:54d1543e23e5	272	ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax	142:54d1543e23e5	273	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	274	return x;
nixnax	142:54d1543e23e5	275	}
nixnax	142:54d1543e23e5	276
nixnax	142:54d1543e23e5	277	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	278	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	279	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	164:c3de3d212c4b	280	/// In WireShark, use "Import Hex File". Import options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	281	void dumpPPPFrame()
nixnax	142:54d1543e23e5	282	{
nixnax	142:54d1543e23e5	283	char pbuf[30];
nixnax	142:54d1543e23e5	284	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	285	checkPc();
nixnax	142:54d1543e23e5	286	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	142:54d1543e23e5	287	checkPc();
nixnax	142:54d1543e23e5	288	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	289	}
nixnax	142:54d1543e23e5	290	checkPc();
nixnax	142:54d1543e23e5	291	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	142:54d1543e23e5	292	checkPc();
nixnax	142:54d1543e23e5	293	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	294	}
nixnax	142:54d1543e23e5	295
nixnax	142:54d1543e23e5	296	/// Process a received PPP frame
nixnax	142:54d1543e23e5	297	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	298	{
nixnax	142:54d1543e23e5	299	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	300	if(start==end) {
nixnax	142:54d1543e23e5	301	return; // empty frame
nixnax	142:54d1543e23e5	302	}
nixnax	145:098b6ed2f7f2	303	fcsReset();
nixnax	142:54d1543e23e5	304	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	305	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	306	int unstuff=0;
nixnax	142:54d1543e23e5	307	int idx = start;
nixnax	142:54d1543e23e5	308	while(1) {
nixnax	142:54d1543e23e5	309	checkPc();
nixnax	142:54d1543e23e5	310	if (unstuff==0) {
nixnax	142:54d1543e23e5	311	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	312	else {
nixnax	142:54d1543e23e5	313	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	314	ppp.pkt.len++;
nixnax	142:54d1543e23e5	315	dest++;
nixnax	145:098b6ed2f7f2	316	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	317	}
nixnax	142:54d1543e23e5	318	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	319	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	320	ppp.pkt.len++;
nixnax	142:54d1543e23e5	321	dest++;
nixnax	145:098b6ed2f7f2	322	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	323	unstuff=0;
nixnax	142:54d1543e23e5	324	}
nixnax	142:54d1543e23e5	325	idx = (idx+1) & (RXBUFLEN-1);
nixnax	142:54d1543e23e5	326	if (idx == end) break;
nixnax	142:54d1543e23e5	327	}
nixnax	145:098b6ed2f7f2	328	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	329	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	330	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	331	determinePacketType();
nixnax	142:54d1543e23e5	332	} else {
nixnax	142:54d1543e23e5	333	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	334	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	335	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	336	checkPc();
nixnax	142:54d1543e23e5	337	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	142:54d1543e23e5	338	checkPc();
nixnax	142:54d1543e23e5	339	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	340	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	341	#endif
nixnax	142:54d1543e23e5	342	}
nixnax	142:54d1543e23e5	343	}
nixnax	142:54d1543e23e5	344
nixnax	142:54d1543e23e5	345	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	346	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	347	{
nixnax	142:54d1543e23e5	348	checkPc(); // check input
nixnax	142:54d1543e23e5	349	pc.putc(ch);
nixnax	142:54d1543e23e5	350	checkPc();
nixnax	142:54d1543e23e5	351	}
nixnax	142:54d1543e23e5	352
nixnax	142:54d1543e23e5	353	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	354	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	355	{
nixnax	142:54d1543e23e5	356	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	357	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	358	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	359	} else {
nixnax	142:54d1543e23e5	360	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	361	}
nixnax	142:54d1543e23e5	362	}
nixnax	142:54d1543e23e5	363
nixnax	142:54d1543e23e5	364	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	365	void sendPppFrame()
nixnax	143:c5019f856a56	366	{
nixnax	172:449dd7a28955	367	ppp.responseCounter++; // count the number of ppp frames we send
nixnax	145:098b6ed2f7f2	368	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	369	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	370	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	371	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	372	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	373	wait_us(86); // wait one character time
nixnax	142:54d1543e23e5	374	checkPc();
nixnax	142:54d1543e23e5	375	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	376	}
nixnax	142:54d1543e23e5	377	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	378	}
nixnax	142:54d1543e23e5	379
nixnax	143:c5019f856a56	380	/// 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	381	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	382	{
nixnax	143:c5019f856a56	383	int result=0;
nixnax	143:c5019f856a56	384	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	385	return result;
nixnax	143:c5019f856a56	386	}
nixnax	143:c5019f856a56	387
nixnax	177:dab9e685af53	388	/// convert 4-byte ip address to 32-bit
nixnax	179:ba2b2ddd0da5	389	unsigned int ip( int a, int b, int c, int d)
nixnax	179:ba2b2ddd0da5	390	{
nixnax	177:dab9e685af53	391	return a<<24 \| b<<16 \| c<<8 \| d;
nixnax	177:dab9e685af53	392	}
nixnax	177:dab9e685af53	393
nixnax	142:54d1543e23e5	394	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	395	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	396	{
nixnax	142:54d1543e23e5	397	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	173:6774a0c851c4	398	if(ppp.ipcp->request[0]==3) {
nixnax	143:c5019f856a56	399	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	173:6774a0c851c4	400	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	401	}
nixnax	143:c5019f856a56	402
nixnax	167:ff8a2d8beeb1	403	ppp.ipcp->code=2; // change code to ack
nixnax	144:01d98cf7738e	404	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	405
nixnax	142:54d1543e23e5	406	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	167:ff8a2d8beeb1	407	ppp.ipcp->code=1; // change code to request
nixnax	167:ff8a2d8beeb1	408	ppp.ipcp->lengthR = __REV16( 4 ); // 4 is minimum length - no options in this request
nixnax	167:ff8a2d8beeb1	409	ppp.pkt.len=4+4+2; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	410	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	411	}
nixnax	142:54d1543e23e5	412
nixnax	142:54d1543e23e5	413	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	414	void ipcpAckHandler()
nixnax	142:54d1543e23e5	415	{
nixnax	142:54d1543e23e5	416	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	417	}
nixnax	142:54d1543e23e5	418
nixnax	143:c5019f856a56	419	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	420	/// 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	421	void ipcpNackHandler()
nixnax	142:54d1543e23e5	422	{
nixnax	146:a45f49a2b29c	423	debugPrintf("Their IPCP Nack\n");
nixnax	173:6774a0c851c4	424	if (ppp.ipcp->request[0]==3) { // check if the NACK contains an IP address parameter
nixnax	167:ff8a2d8beeb1	425	ppp.ipcp->code=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	426	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	427	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	428	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	429	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	430	}
nixnax	142:54d1543e23e5	431	}
nixnax	142:54d1543e23e5	432
nixnax	142:54d1543e23e5	433	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	434	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	435	{
nixnax	142:54d1543e23e5	436	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	437	}
nixnax	142:54d1543e23e5	438
nixnax	142:54d1543e23e5	439	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	440	void IPCPframe()
nixnax	142:54d1543e23e5	441	{
nixnax	167:ff8a2d8beeb1	442	int action = ppp.ipcp->code; // packet type is here
nixnax	167:ff8a2d8beeb1	443	switch (action) {
nixnax	142:54d1543e23e5	444	case 1:
nixnax	142:54d1543e23e5	445	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	446	break;
nixnax	142:54d1543e23e5	447	case 2:
nixnax	142:54d1543e23e5	448	ipcpAckHandler();
nixnax	142:54d1543e23e5	449	break;
nixnax	142:54d1543e23e5	450	case 3:
nixnax	142:54d1543e23e5	451	ipcpNackHandler();
nixnax	142:54d1543e23e5	452	break;
nixnax	142:54d1543e23e5	453	default:
nixnax	142:54d1543e23e5	454	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	455	}
nixnax	142:54d1543e23e5	456	}
nixnax	142:54d1543e23e5	457
nixnax	142:54d1543e23e5	458	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	161:d59f778bc8ab	459	unsigned int dataCheckSum(char * ptr, int len, int restart)
nixnax	142:54d1543e23e5	460	{
nixnax	159:4d1bf96a59cd	461	unsigned int i,hi,lo;
nixnax	142:54d1543e23e5	462	unsigned char placeHolder;
nixnax	161:d59f778bc8ab	463	if (restart) ppp.sum=0;
nixnax	142:54d1543e23e5	464	if (len&1) {
nixnax	142:54d1543e23e5	465	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	466	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	467	}
nixnax	142:54d1543e23e5	468	i=0;
nixnax	142:54d1543e23e5	469	while ( i<len ) {
nixnax	142:54d1543e23e5	470	checkPc();
nixnax	142:54d1543e23e5	471	hi = ptr[i++];
nixnax	142:54d1543e23e5	472	lo = ptr[i++];
nixnax	159:4d1bf96a59cd	473	ppp.sum = ppp.sum + ((hi<<8)\|lo);
nixnax	142:54d1543e23e5	474	}
nixnax	142:54d1543e23e5	475	if (len&1) {
nixnax	142:54d1543e23e5	476	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	477	}
nixnax	159:4d1bf96a59cd	478	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax	159:4d1bf96a59cd	479	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax	159:4d1bf96a59cd	480	return ~ppp.sum;
nixnax	142:54d1543e23e5	481	}
nixnax	142:54d1543e23e5	482
nixnax	142:54d1543e23e5	483	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	484	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	485	{
nixnax	161:d59f778bc8ab	486	ppp.ip->checksumR=0; // zero the checsum in the IP header
nixnax	161:d59f778bc8ab	487	int len = 4 * ppp.ip->headerLength; // length of IP header in bytes
nixnax	161:d59f778bc8ab	488	unsigned int sum = dataCheckSum(ppp.ipStart,len,1);
nixnax	161:d59f778bc8ab	489	ppp.ip->checksumR = __REV16( sum ); // insert fresh checksum
nixnax	146:a45f49a2b29c	490	}
nixnax	146:a45f49a2b29c	491
nixnax	147:0f40005cbc5f	492	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	493	void swapIpAddresses()
nixnax	147:0f40005cbc5f	494	{
nixnax	162:594729c0e5c1	495	unsigned int tempHold;
nixnax	162:594729c0e5c1	496	tempHold = ppp.ip->srcAdrR; // tempHold <- source IP
nixnax	162:594729c0e5c1	497	ppp.ip->srcAdrR = ppp.ip->dstAdrR; // source <- dest
nixnax	162:594729c0e5c1	498	ppp.ip->dstAdrR = tempHold; // dest <- tempHold*/
nixnax	147:0f40005cbc5f	499	}
nixnax	147:0f40005cbc5f	500
nixnax	149:969d98f6fb88	501	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	502	void swapIpPorts()
nixnax	149:969d98f6fb88	503	{
nixnax	173:6774a0c851c4	504	int headerSizeIP = 4 * (ppp.ip->headerLength); // calculate size of IP header
nixnax	173:6774a0c851c4	505	char * ipSrcPort = ppp.ipStart + headerSizeIP + 0; // ip source port location
nixnax	173:6774a0c851c4	506	char * ipDstPort = ppp.ipStart + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	507	char tempHold[2];
nixnax	149:969d98f6fb88	508	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	509	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	510	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	511	}
nixnax	149:969d98f6fb88	512
nixnax	170:3d3b2126181c	513	/// Build the "pseudo header" required for UDP and TCP, then calculate its checksum
nixnax	170:3d3b2126181c	514	void checkSumPseudoHeader( unsigned int packetLength )
nixnax	170:3d3b2126181c	515	{
nixnax	170:3d3b2126181c	516	// 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	517	pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax	170:3d3b2126181c	518	pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax	170:3d3b2126181c	519	pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax	170:3d3b2126181c	520	pseudoHeader.zero = 0; // zero byte
nixnax	170:3d3b2126181c	521	pseudoHeader.protocol = ppp.ip->protocol; // protocol number (udp or tcp)
nixnax	170:3d3b2126181c	522	pseudoHeader.lengthR = __REV16( packetLength ); // size of tcp or udp packet
nixnax	170:3d3b2126181c	523	dataCheckSum(pseudoHeader.start, 12, 1); // calculate this header's checksum
nixnax	170:3d3b2126181c	524	}
nixnax	170:3d3b2126181c	525
nixnax	171:46b36d4edd1d	526	/// initialize an IP packet to send
nixnax	171:46b36d4edd1d	527	void initIP (unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, unsigned int protocol)
nixnax	171:46b36d4edd1d	528	{
nixnax	171:46b36d4edd1d	529	ppp.ppp->address = 0xff;
nixnax	171:46b36d4edd1d	530	ppp.ppp->control = 3;
nixnax	171:46b36d4edd1d	531	ppp.ppp->protocolR = __REV16( 0x0021 );
nixnax	171:46b36d4edd1d	532	ppp.ip->version = 4;
nixnax	171:46b36d4edd1d	533	ppp.ip->headerLength = 5; // 5 words = 20 bytes
nixnax	171:46b36d4edd1d	534	ppp.ip->identR = __REV16(ppp.ipData.ident++); // insert our ident
nixnax	171:46b36d4edd1d	535	ppp.ip->dontFragment=1;
nixnax	171:46b36d4edd1d	536	ppp.ip->ttl=128;
nixnax	171:46b36d4edd1d	537	ppp.ip->protocol = protocol; // udp
nixnax	171:46b36d4edd1d	538	ppp.ip->srcAdrR = __REV(srcIp);
nixnax	171:46b36d4edd1d	539	ppp.ip->dstAdrR = __REV(dstIp);
nixnax	171:46b36d4edd1d	540	ppp.udpStart = ppp.ipStart + 20; // calculate start of udp header
nixnax	171:46b36d4edd1d	541	ppp.udp->srcPortR = __REV16(srcPort); // source port
nixnax	171:46b36d4edd1d	542	ppp.udp->dstPortR = __REV16(dstPort); // dest port
nixnax	171:46b36d4edd1d	543	}
nixnax	171:46b36d4edd1d	544
nixnax	171:46b36d4edd1d	545
nixnax	171:46b36d4edd1d	546	/// Build a UDP packet from scratch
nixnax	171:46b36d4edd1d	547	void sendUdp(unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, char * message,int msgLen)
nixnax	171:46b36d4edd1d	548	{
nixnax	171:46b36d4edd1d	549	struct {
nixnax	171:46b36d4edd1d	550	unsigned int ipAll; // length of entire ip packet
nixnax	171:46b36d4edd1d	551	unsigned int ipHeader; // length of ip header
nixnax	171:46b36d4edd1d	552	unsigned int udpAll; // length of entire udp packet
nixnax	171:46b36d4edd1d	553	unsigned int udpData; // length of udp data segment
nixnax	171:46b36d4edd1d	554	} len;
nixnax	171:46b36d4edd1d	555	len.ipHeader = 20; // ip header length
nixnax	171:46b36d4edd1d	556	len.udpData = msgLen; // udp data size
nixnax	171:46b36d4edd1d	557	len.udpAll = len.udpData+8; // update local udp packet length
nixnax	171:46b36d4edd1d	558	len.ipAll = len.ipHeader + len.udpAll; // update IP Length
nixnax	171:46b36d4edd1d	559	initIP(srcIp, dstIp, srcPort, dstPort, 17); // init a UDP packet
nixnax	171:46b36d4edd1d	560	ppp.ip->lengthR = __REV16(len.ipAll); // update IP length in buffer
nixnax	171:46b36d4edd1d	561	ppp.udpStart = ppp.ipStart + len.ipHeader; // calculate start of udp header
nixnax	171:46b36d4edd1d	562	memcpy( ppp.udp->data, message, len.udpData ); // copy the message to the buffer
nixnax	171:46b36d4edd1d	563	ppp.udp->lengthR = __REV16(len.udpAll); // update UDP length in buffer
nixnax	171:46b36d4edd1d	564	ppp.pkt.len = len.ipAll+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	565	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	566	checkSumPseudoHeader( len.udpAll ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	567	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	568	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,len.udpAll, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	569	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	570	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	571	}
nixnax	171:46b36d4edd1d	572
nixnax	146:a45f49a2b29c	573	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	574	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	575	void UDPpacket()
nixnax	146:a45f49a2b29c	576	{
nixnax	163:d1b4328e9f08	577	struct {
nixnax	163:d1b4328e9f08	578	unsigned int all; // length of entire ip packet
nixnax	163:d1b4328e9f08	579	unsigned int header; // length of ip header
nixnax	163:d1b4328e9f08	580	} ipLength;
nixnax	163:d1b4328e9f08	581
nixnax	163:d1b4328e9f08	582	struct {
nixnax	165:c47826d07e0d	583	unsigned int all; // length of entire udp packet
nixnax	163:d1b4328e9f08	584	unsigned int data; // length of udp data segment
nixnax	163:d1b4328e9f08	585	} udpLength;
nixnax	163:d1b4328e9f08	586
nixnax	163:d1b4328e9f08	587	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	163:d1b4328e9f08	588	ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	171:46b36d4edd1d	589	udpLength.all = __REV16( ppp.udp->lengthR ); // size of udp packet
nixnax	163:d1b4328e9f08	590	udpLength.data = udpLength.all - 8; // size of udp data
nixnax	147:0f40005cbc5f	591
nixnax	146:a45f49a2b29c	592	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	171:46b36d4edd1d	593	char * srcIP = ppp.ip->srcAdrPtr; // IP source
nixnax	171:46b36d4edd1d	594	char * dstIP = ppp.ip->dstAdrPtr; //IP destination
nixnax	163:d1b4328e9f08	595
nixnax	171:46b36d4edd1d	596	unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); // integer of UDP source port
nixnax	171:46b36d4edd1d	597	unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); // integer of UDP dest port
nixnax	163:d1b4328e9f08	598
nixnax	163:d1b4328e9f08	599	if(v0) {
nixnax	163:d1b4328e9f08	600	debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
nixnax	163:d1b4328e9f08	601	debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
nixnax	163:d1b4328e9f08	602	debugPrintf("Len %03d", udpLength);
nixnax	163:d1b4328e9f08	603	}
nixnax	146:a45f49a2b29c	604	if (v1) {
nixnax	163:d1b4328e9f08	605	int printSize = udpLength.data;
nixnax	146:a45f49a2b29c	606	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	607	for (int i=0; i<printSize; i++) {
nixnax	163:d1b4328e9f08	608	char ch = ppp.udp->data[i];
nixnax	146:a45f49a2b29c	609	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	610	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	611	} else {
nixnax	146:a45f49a2b29c	612	debugPrintf("_");
nixnax	146:a45f49a2b29c	613	}
nixnax	146:a45f49a2b29c	614	}
nixnax	146:a45f49a2b29c	615	}
nixnax	146:a45f49a2b29c	616	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	617	#endif
nixnax	163:d1b4328e9f08	618	int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
nixnax	163:d1b4328e9f08	619	int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	620	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	146:a45f49a2b29c	621	if (echoFound) {
nixnax	171:46b36d4edd1d	622	swapIpAddresses(); // swap IP source and destination
nixnax	171:46b36d4edd1d	623	swapIpPorts(); // swap IP source and destination ports
nixnax	163:d1b4328e9f08	624	memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	170:3d3b2126181c	625	int n=0;
nixnax	170:3d3b2126181c	626	n=n+sprintf(n+ppp.udp->data+udpLength.data, "} UDP Server: PPP-Blinky\n"); // an appendix
nixnax	168:c77eb908042a	627	udpLength.data = udpLength.data + n; // update udp data size with the size of the appendix
nixnax	171:46b36d4edd1d	628	// we may have changed data length, update all the lengths
nixnax	171:46b36d4edd1d	629	udpLength.all = udpLength.data+8; // update local udp packet length
nixnax	171:46b36d4edd1d	630	ipLength.all = ipLength.header + udpLength.all; // update IP Length
nixnax	171:46b36d4edd1d	631	ppp.ip->lengthR = __REV16(ipLength.all); // update IP length in buffer
nixnax	171:46b36d4edd1d	632	ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
nixnax	171:46b36d4edd1d	633	ppp.pkt.len = ipLength.all+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	634	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	635	checkSumPseudoHeader( udpLength.all ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	636	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	637	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,udpLength.all, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	638	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	639	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	640	} else if ( testFound ) {
nixnax	171:46b36d4edd1d	641	unsigned int sI = __REV( ppp.ip->srcAdrR );
nixnax	171:46b36d4edd1d	642	unsigned int dI = __REV( ppp.ip->dstAdrR );
nixnax	171:46b36d4edd1d	643	unsigned int sp = __REV16( ppp.udp->srcPortR );
nixnax	171:46b36d4edd1d	644	unsigned int dp = __REV16( ppp.udp->dstPortR );
nixnax	172:449dd7a28955	645	int n=sprintf(ppp.pkt.buf+200,"Response Count %d\n", ppp.responseCounter);
nixnax	171:46b36d4edd1d	646	sendUdp(dI,sI,dp,sp,ppp.pkt.buf+200,n); // build a udp packet from the ground up
nixnax	146:a45f49a2b29c	647	}
nixnax	146:a45f49a2b29c	648	}
nixnax	142:54d1543e23e5	649	}
nixnax	142:54d1543e23e5	650
nixnax	174:e5a3f16421a5	651	/// UDP demo that sends a udp packet containing a character received from the second debug serial port.
nixnax	174:e5a3f16421a5	652	/// Sends a 48 byte IP/UDP header for every 1 byte of data so line-mode would probably be better.
nixnax	178:3f17aa0ce5ce	653	/// If you want ip packets from ppp blinky to be routed to other networks, ensure you have ip routing enabled.
nixnax	178:3f17aa0ce5ce	654	/// See http://www.wikihow.com/Enable-IP-Routing.
nixnax	179:ba2b2ddd0da5	655	/// Also ensure that the firewall on the receiving machine has the receiving UDP port (12345 in this example) enabled.
nixnax	179:ba2b2ddd0da5	656	/// The netcat UDP receive command on the remote host would be: nc -ul 12345
nixnax	174:e5a3f16421a5	657	void sendUdpData()
nixnax	174:e5a3f16421a5	658	{
nixnax	174:e5a3f16421a5	659	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	179:ba2b2ddd0da5	660	if (ppp.online) {
nixnax	179:ba2b2ddd0da5	661	if (xx.readable()) {
nixnax	179:ba2b2ddd0da5	662	char inchar = xx.getc();
nixnax	179:ba2b2ddd0da5	663	xx.putc( inchar ); // echo the received character on the debug serial port
nixnax	179:ba2b2ddd0da5	664	sendUdp(ip(172,10,10,2), ip(192,168,0,109), 1, 12345, &inchar, 1); // send a 1 byte UDP message to a remote machine at IP 192.168.0.109:12345
nixnax	179:ba2b2ddd0da5	665	}
nixnax	174:e5a3f16421a5	666	}
nixnax	174:e5a3f16421a5	667	#endif
nixnax	174:e5a3f16421a5	668	}
nixnax	174:e5a3f16421a5	669
nixnax	142:54d1543e23e5	670	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	671	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	672	{
nixnax	165:c47826d07e0d	673	struct {
nixnax	165:c47826d07e0d	674	unsigned int all; // length of entire ip packet
nixnax	165:c47826d07e0d	675	unsigned int header; // length of ip header
nixnax	165:c47826d07e0d	676	} ipLength;
nixnax	165:c47826d07e0d	677	struct {
nixnax	165:c47826d07e0d	678	unsigned int all; // length of entire udp packet
nixnax	165:c47826d07e0d	679	unsigned int data; // length of udp data segment
nixnax	165:c47826d07e0d	680	} icmpLength;
nixnax	165:c47826d07e0d	681	ipLength.all = __REV16( ppp.ip->lengthR ); // length of ip packet
nixnax	165:c47826d07e0d	682	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	165:c47826d07e0d	683	ppp.icmpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	165:c47826d07e0d	684	icmpLength.all = ipLength.all - ipLength.header; // length of icmp packet
nixnax	165:c47826d07e0d	685	icmpLength.data = icmpLength.all - 8; // length of icmp data
nixnax	142:54d1543e23e5	686	#define ICMP_TYPE_PING_REQUEST 8
nixnax	165:c47826d07e0d	687	if ( ppp.icmp->type == ICMP_TYPE_PING_REQUEST ) {
nixnax	165:c47826d07e0d	688	ppp.ip->ttl--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	689	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	167:ff8a2d8beeb1	690	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	691	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	165:c47826d07e0d	692	int icmpIdent = __REV16( ppp.ip->identR ); // byte reversed - big endian
nixnax	165:c47826d07e0d	693	int icmpSequence = __REV16( ppp.icmp->sequenceR ); // byte reversed - big endian
nixnax	142:54d1543e23e5	694	if(1) {
nixnax	142:54d1543e23e5	695	char pbuf[50];
nixnax	142:54d1543e23e5	696	checkPc();
nixnax	142:54d1543e23e5	697	sprintf(pbuf, "ICMP PING %d.%d.%d.%d %d.%d.%d.%d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax	142:54d1543e23e5	698	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	699	checkPc();
nixnax	142:54d1543e23e5	700	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	142:54d1543e23e5	701	checkPc();
nixnax	142:54d1543e23e5	702	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	703	}
nixnax	142:54d1543e23e5	704	#endif
nixnax	147:0f40005cbc5f	705	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	706	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	707	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	165:c47826d07e0d	708	ppp.icmp->type = ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	165:c47826d07e0d	709	ppp.icmp->checkSumR = 0; // zero the checksum for recalculation
nixnax	165:c47826d07e0d	710	unsigned int sum = dataCheckSum(ppp.icmpStart, icmpLength.all, 1); // icmp checksum
nixnax	165:c47826d07e0d	711	ppp.icmp->checkSumR = __REV16( sum ); // save big-endian icmp checksum
nixnax	142:54d1543e23e5	712
nixnax	165:c47826d07e0d	713	int printSize = icmpLength.data; // exclude size of icmp header
nixnax	142:54d1543e23e5	714	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	715	if (0) {
nixnax	142:54d1543e23e5	716	for (int i=0; i<printSize; i++) {
nixnax	165:c47826d07e0d	717	char ch = ppp.icmp->data[i];
nixnax	142:54d1543e23e5	718	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	719	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	720	} else {
nixnax	142:54d1543e23e5	721	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	722	}
nixnax	142:54d1543e23e5	723	}
nixnax	142:54d1543e23e5	724	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	725	}
nixnax	144:01d98cf7738e	726	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	727	} else {
nixnax	142:54d1543e23e5	728	if (v0) {
nixnax	165:c47826d07e0d	729	debugPrintf("ICMP type=%x \n", ppp.icmp->type);
nixnax	142:54d1543e23e5	730	}
nixnax	142:54d1543e23e5	731	}
nixnax	142:54d1543e23e5	732	}
nixnax	142:54d1543e23e5	733
nixnax	142:54d1543e23e5	734	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	735	void IGMPpacket()
nixnax	142:54d1543e23e5	736	{
nixnax	142:54d1543e23e5	737	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	738	}
nixnax	142:54d1543e23e5	739
nixnax	142:54d1543e23e5	740	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	741	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	742	{
nixnax	142:54d1543e23e5	743	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	744	checkPc(); // we are expecting the first character of the next packet
nixnax	155:9c6a1d249e26	745	int IPv4Id = __REV16(ppp.ip->identR);
nixnax	152:025c73b6c0a9	746	char pbuf[80]; // local print buffer
nixnax	142:54d1543e23e5	747	int n=0;
nixnax	142:54d1543e23e5	748	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	749	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	750	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	751	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	167:ff8a2d8beeb1	752	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	753	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	142:54d1543e23e5	754	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	755	#endif
nixnax	142:54d1543e23e5	756	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	757	#ifndef TCP_HEADER_DUMP_YES
nixnax	160:bd701ad564cb	758	putsWhileCheckingInput('\x1b[30m\n'); // if there's no TCP header dump we terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	759	#endif
nixnax	142:54d1543e23e5	760	#endif
nixnax	142:54d1543e23e5	761	}
nixnax	142:54d1543e23e5	762
nixnax	142:54d1543e23e5	763	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	764	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	765	{
nixnax	142:54d1543e23e5	766	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	155:9c6a1d249e26	767	char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	768	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	769	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	155:9c6a1d249e26	770	memset(flagString,'.', 8); // fill string with "........"
nixnax	156:163c23249731	771	if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax	156:163c23249731	772	if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax	156:163c23249731	773	if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax	156:163c23249731	774	if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax	156:163c23249731	775	if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax	156:163c23249731	776	if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax	156:163c23249731	777	if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax	156:163c23249731	778	if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax	155:9c6a1d249e26	779	flagString[8]=0; // null terminate string
nixnax	142:54d1543e23e5	780	#else
nixnax	156:163c23249731	781	if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax	156:163c23249731	782	if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax	156:163c23249731	783	if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax	156:163c23249731	784	if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax	156:163c23249731	785	if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax	155:9c6a1d249e26	786	flagString[1]=0; // null terminate string
nixnax	142:54d1543e23e5	787	#endif
nixnax	155:9c6a1d249e26	788	putsWhileCheckingInput( flagString );
nixnax	142:54d1543e23e5	789	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	790	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	791	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	160:bd701ad564cb	792	#else
nixnax	160:bd701ad564cb	793	putsWhileCheckingInput("\x1b[30m"); // write a black color after every packet
nixnax	142:54d1543e23e5	794	#endif
nixnax	156:163c23249731	795	if( outGoing && ppp.tcp->flag.fin ) { // ACK/FIN - if this is an outgoing FIN it's the end of a tcp conversation
nixnax	160:bd701ad564cb	796	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end (except for final ack) of an HTTP conversation
nixnax	142:54d1543e23e5	797	}
nixnax	142:54d1543e23e5	798	#endif
nixnax	142:54d1543e23e5	799	}
nixnax	142:54d1543e23e5	800
nixnax	143:c5019f856a56	801	/// Encode a buffer in base-64
nixnax	184:4133f557d4d4	802	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	803	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	804	{
nixnax	142:54d1543e23e5	805	int i,j,a,b,c;
nixnax	142:54d1543e23e5	806	i=0;
nixnax	142:54d1543e23e5	807	j=0;
nixnax	142:54d1543e23e5	808	while(1) {
nixnax	142:54d1543e23e5	809	if (i<len) {
nixnax	142:54d1543e23e5	810	a = in[i++];
nixnax	142:54d1543e23e5	811	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	812	} else break;
nixnax	142:54d1543e23e5	813	if (i<len) {
nixnax	142:54d1543e23e5	814	b = in[i++];
nixnax	142:54d1543e23e5	815	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	816	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	817	} else out[j++] = '=';
nixnax	142:54d1543e23e5	818	if (i<len) {
nixnax	142:54d1543e23e5	819	c = in[i++];
nixnax	142:54d1543e23e5	820	j--;
nixnax	142:54d1543e23e5	821	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	822	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	823	} else out[j++] = '=';
nixnax	142:54d1543e23e5	824	}
nixnax	142:54d1543e23e5	825	out[j]=0;
nixnax	142:54d1543e23e5	826	}
nixnax	142:54d1543e23e5	827
nixnax	160:bd701ad564cb	828	/// Handle a request for an http websocket.
nixnax	160:bd701ad564cb	829	/// 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	830	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	831	{
nixnax	142:54d1543e23e5	832	int n=0; // byte counter
nixnax	184:4133f557d4d4	833	char * key = strstr(dataStart, "Sec-WebSocket-Key:"); // search for the key in the payload
nixnax	142:54d1543e23e5	834	if (key != NULL) {
nixnax	184:4133f557d4d4	835	key = key + 18; // skip over the key ident string "Sec-WebSocket-Key:"
nixnax	142:54d1543e23e5	836	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	184:4133f557d4d4	837	while ( strchr(lut, *key) == NULL) key++; // skip non-valid base-64 characters (whitespace)
nixnax	184:4133f557d4d4	838	char challenge [80];
nixnax	184:4133f557d4d4	839	int i=0;
nixnax	184:4133f557d4d4	840	char * copyTo = challenge;
nixnax	184:4133f557d4d4	841	while (strchr(lut, *key) != NULL) { // copy while we see valid base-64 characters
nixnax	184:4133f557d4d4	842	if (i++ >40) break; // prevent buffer overflow
nixnax	184:4133f557d4d4	843	copyTo++ = key++; // copy next valid base-64 character
nixnax	184:4133f557d4d4	844	}
nixnax	184:4133f557d4d4	845	strcpy(copyTo,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"); // append websocket gui code
nixnax	184:4133f557d4d4	846	if (0) debugPrintf("Challenge is %s\n", challenge); // the string we hash for the challenge
nixnax	142:54d1543e23e5	847	char shaOutput [20]; // sha1 output
nixnax	184:4133f557d4d4	848	sha1( shaOutput, challenge, strlen(challenge)); // hash the challenge
nixnax	142:54d1543e23e5	849	char encOut[50];
nixnax	184:4133f557d4d4	850	enc64( shaOutput, encOut, 20); // base-64 encode
nixnax	142:54d1543e23e5	851	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	852	char * version = challenge;
nixnax	184:4133f557d4d4	853	strncpy(version, versionstring,70); // copy their version string
nixnax	142:54d1543e23e5	854	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	855	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	856	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	857	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	858	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	859	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	860	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	861	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	862	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	863	}
nixnax	142:54d1543e23e5	864	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	865	}
nixnax	142:54d1543e23e5	866
nixnax	142:54d1543e23e5	867	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	868	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	869	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	870	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	871	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	872
nixnax	142:54d1543e23e5	873	/// respond to an HTTP request
nixnax	185:4cd8f91e9d49	874	int httpResponse(char * dataStart, int * flags)
nixnax	142:54d1543e23e5	875	{
nixnax	142:54d1543e23e5	876	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	877	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	160:bd701ad564cb	878	if (n>0) return n; // if n>0 we already have a response, so return
nixnax	142:54d1543e23e5	879
nixnax	142:54d1543e23e5	880	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	881	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	882	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	185:4cd8f91e9d49	883	*flags = TCP_FLAG_ACK \| TCP_FLAG_FIN; // the default case is that we close the connection
nixnax	142:54d1543e23e5	884
nixnax	142:54d1543e23e5	885	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	886	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	887	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	888	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	889	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	142:54d1543e23e5	890	if( (httpGetRoot==0) \|\| (httpGetx==0) ) {
nixnax	142:54d1543e23e5	891	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	892	} else {
nixnax	142:54d1543e23e5	893	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	894	}
nixnax	142:54d1543e23e5	895	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	896	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	897	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	898	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	142:54d1543e23e5	899	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	900	nHeader=n; // size of HTTP header
nixnax	185:4cd8f91e9d49	901
nixnax	142:54d1543e23e5	902	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	903	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	904	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	905	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	185:4cd8f91e9d49	906
nixnax	142:54d1543e23e5	907	} else if ( (httpGet5 == 'w') && (httpGet6 == 's') ) { // "ws" is a special page for websocket demo
nixnax	142:54d1543e23e5	908	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	909	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	185:4cd8f91e9d49	910	*flags = TCP_FLAG_ACK \| TCP_FLAG_PSH; // for a websocket page we do NOT close the connection
nixnax	142:54d1543e23e5	911	} else {
nixnax	142:54d1543e23e5	912	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	913	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	914	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	915	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	916	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	917	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	918	#else
nixnax	142:54d1543e23e5	919	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	167:ff8a2d8beeb1	920	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	921	}
nixnax	142:54d1543e23e5	922	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	923	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	924	#endif
nixnax	142:54d1543e23e5	925	} else {
nixnax	142:54d1543e23e5	926	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	927	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	928	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	929	}
nixnax	142:54d1543e23e5	930	}
nixnax	142:54d1543e23e5	931	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	932	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	933	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	934	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	935	return n; // total byte size of our response
nixnax	142:54d1543e23e5	936	}
nixnax	142:54d1543e23e5	937
nixnax	160:bd701ad564cb	938	/// Handle TCP data that is not an HTTP GET.
nixnax	160:bd701ad564cb	939	/// This is handy when for example you want to use netcat (nc.exe) to talk to PPP-Blinky.
nixnax	160:bd701ad564cb	940	/// This could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	941	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	942	{
nixnax	142:54d1543e23e5	943	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	944	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	160:bd701ad564cb	945	char mask [4];
nixnax	160:bd701ad564cb	946	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	160:bd701ad564cb	947	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	160:bd701ad564cb	948	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	949	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	950	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	951	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	160:bd701ad564cb	952	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	953	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	954	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	955	dataStart[1]=0; // we don't have mask bytes on
nixnax	160:bd701ad564cb	956	} else {
nixnax	184:4133f557d4d4	957	if ( len > 1 ) { // we assume a length of 1 is a keep-alive or push packet
nixnax	184:4133f557d4d4	958	if (v1) putsWhileCheckingInput("TCP data received\n"); // all other tcp push packets
nixnax	184:4133f557d4d4	959	}
nixnax	163:d1b4328e9f08	960	}
nixnax	142:54d1543e23e5	961	return n; // total byte size of our response
nixnax	142:54d1543e23e5	962	}
nixnax	142:54d1543e23e5	963
nixnax	173:6774a0c851c4	964	/// dump the TCP data to the debug serial port
nixnax	173:6774a0c851c4	965	void dumpDataTCP(int outGoing)
nixnax	173:6774a0c851c4	966	{
nixnax	173:6774a0c851c4	967	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	173:6774a0c851c4	968	if (v2) {
nixnax	173:6774a0c851c4	969	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	173:6774a0c851c4	970	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	971	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax	173:6774a0c851c4	972	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	973	ppp.tcpData = ppp.tcpStart + headerSizeTcp; // start of tcp data
nixnax	173:6774a0c851c4	974	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	173:6774a0c851c4	975	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	173:6774a0c851c4	976	char pbuf[80]; // local print buffer
nixnax	173:6774a0c851c4	977	int n=0;
nixnax	173:6774a0c851c4	978	checkPc();
nixnax	173:6774a0c851c4	979	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	173:6774a0c851c4	980	checkPc();
nixnax	173:6774a0c851c4	981	n=n+sprintf(pbuf+n, "IP:%d ipHeader:%d tcpHeader:%d tcpData:%d\n", packetLengthIp, headerSizeIp, headerSizeTcp, tcpDataSize); // 1 for more verbose
nixnax	184:4133f557d4d4	982	if (n>70) putsWhileCheckingInput("n>pbuf overflow in dumpDataTCP()\n");
nixnax	173:6774a0c851c4	983	checkPc();
nixnax	173:6774a0c851c4	984	putsWhileCheckingInput( pbuf );
nixnax	173:6774a0c851c4	985	if (tcpDataSize > 0) {
nixnax	173:6774a0c851c4	986	ppp.tcpData[tcpDataSize]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	173:6774a0c851c4	987	putsWhileCheckingInput( ppp.tcpData ); // print the tcp payload data
nixnax	173:6774a0c851c4	988	putsWhileCheckingInput("\n");
nixnax	173:6774a0c851c4	989	}
nixnax	173:6774a0c851c4	990	putsWhileCheckingInput( "\x1b[30m" ); // VT100 color code, print black
nixnax	173:6774a0c851c4	991	}
nixnax	173:6774a0c851c4	992	#endif
nixnax	173:6774a0c851c4	993	}
nixnax	173:6774a0c851c4	994
nixnax	142:54d1543e23e5	995	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	996	/// 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	997	void tcpHandler()
nixnax	142:54d1543e23e5	998	{
nixnax	154:18b2bd92f557	999	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	154:18b2bd92f557	1000	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	1001	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate TCP header start
nixnax	154:18b2bd92f557	1002	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	154:18b2bd92f557	1003	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	1004	char * tcpDataIn = ppp.tcpStart + headerSizeTcp; // start of data TCP data after TCP header
nixnax	154:18b2bd92f557	1005	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	154:18b2bd92f557	1006
nixnax	154:18b2bd92f557	1007	unsigned int seq_in = __REV(ppp.tcp->seqTcpR);
nixnax	154:18b2bd92f557	1008	unsigned int ack_in = __REV(ppp.tcp->ackTcpR);
nixnax	142:54d1543e23e5	1009	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	1010	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	1011
nixnax	142:54d1543e23e5	1012	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	173:6774a0c851c4	1013	headerSizeIp=20;
nixnax	173:6774a0c851c4	1014	ppp.ip->headerLength = headerSizeIp/4; // ip header is 20 bytes long
nixnax	173:6774a0c851c4	1015	ppp.ip->lengthR = __REV(40); // 20 ip header + 20 tcp header
nixnax	173:6774a0c851c4	1016	//tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	154:18b2bd92f557	1017	headerSizeTcp = 20; // shorten outgoing TCP header size 20 bytes
nixnax	173:6774a0c851c4	1018	ppp.tcpStart = ppp.ipStart + headerSizeIp; // recalc TCP header start
nixnax	154:18b2bd92f557	1019	ppp.tcp->offset = (headerSizeTcp/4);
nixnax	173:6774a0c851c4	1020	char * tcpDataOut = ppp.tcpStart + headerSizeTcp; // start of outgoing data
nixnax	142:54d1543e23e5	1021
nixnax	142:54d1543e23e5	1022	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	1023	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	160:bd701ad564cb	1024
nixnax	185:4cd8f91e9d49	1025	ppp.tcp->windowR = __REV16( 1200 ); // set tcp window size to 1200 bytes
nixnax	142:54d1543e23e5	1026
nixnax	142:54d1543e23e5	1027	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	1028
nixnax	156:163c23249731	1029	switch ( ppp.tcp->flag.All ) {
nixnax	142:54d1543e23e5	1030	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1031	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1032	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1033	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1034	break;
nixnax	184:4133f557d4d4	1035	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1036	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	184:4133f557d4d4	1037	if ( (ppp.tcp->flag.All == TCP_FLAG_ACK) && (tcpDataSize == 0)) return; // handle zero-size ack messages by ignoring them
nixnax	142:54d1543e23e5	1038	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	179:ba2b2ddd0da5	1039	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // we have data, set the PSH flag
nixnax	185:4cd8f91e9d49	1040	dataLen = httpResponse(tcpDataOut, &flagsOut); // send an http response
nixnax	142:54d1543e23e5	1041	} else {
nixnax	158:841592aed956	1042	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax	179:ba2b2ddd0da5	1043	if (dataLen > 0) flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // if we have any data set the PSH flag
nixnax	142:54d1543e23e5	1044	}
nixnax	142:54d1543e23e5	1045	break;
nixnax	142:54d1543e23e5	1046	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1047	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1048	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1049	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1050	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1051	break;
nixnax	142:54d1543e23e5	1052	default:
nixnax	179:ba2b2ddd0da5	1053	return; // ignore all other packets
nixnax	142:54d1543e23e5	1054	} // switch
nixnax	142:54d1543e23e5	1055
nixnax	142:54d1543e23e5	1056	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1057	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1058	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1059	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1060
nixnax	158:841592aed956	1061	ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	158:841592aed956	1062	ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	160:bd701ad564cb	1063
nixnax	156:163c23249731	1064	ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1065
nixnax	159:4d1bf96a59cd	1066	// recalculate all the header sizes
nixnax	154:18b2bd92f557	1067	tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax	154:18b2bd92f557	1068	int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax	159:4d1bf96a59cd	1069	ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax	142:54d1543e23e5	1070	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	1071
nixnax	142:54d1543e23e5	1072	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1073	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	170:3d3b2126181c	1074	checkSumPseudoHeader( tcpSize ); // get the TCP pseudo-header checksum
nixnax	159:4d1bf96a59cd	1075	ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	161:d59f778bc8ab	1076	unsigned int pseudoHeaderSum=dataCheckSum(ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax	159:4d1bf96a59cd	1077	ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	160:bd701ad564cb	1078
nixnax	170:3d3b2126181c	1079	dumpHeaderIP(1); // dump outgoing IP header before sending the frame
nixnax	170:3d3b2126181c	1080	dumpHeaderTCP(1); // dump outgoing TCP header before sending the frame
nixnax	173:6774a0c851c4	1081	dumpDataTCP(1); // dump outgoing TCP data before sending the frame
nixnax	182:f039ec218c9f	1082	if (0) wait_ms(45); // 45 ms delay before sending frame - a typical internet delay time
nixnax	144:01d98cf7738e	1083	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1084	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1085	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1086	}
nixnax	142:54d1543e23e5	1087
nixnax	142:54d1543e23e5	1088	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1089	void TCPpacket()
nixnax	142:54d1543e23e5	1090	{
nixnax	173:6774a0c851c4	1091	dumpHeaderIP(0); // dump incoming packet IP header
nixnax	173:6774a0c851c4	1092	dumpHeaderTCP(0); // dump incoming packet TCP header
nixnax	173:6774a0c851c4	1093	dumpDataTCP(0); // dump incoming packet data
nixnax	142:54d1543e23e5	1094	tcpHandler();
nixnax	142:54d1543e23e5	1095	}
nixnax	142:54d1543e23e5	1096
nixnax	142:54d1543e23e5	1097	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1098	void otherProtocol()
nixnax	142:54d1543e23e5	1099	{
nixnax	142:54d1543e23e5	1100	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1101	}
nixnax	142:54d1543e23e5	1102
nixnax	142:54d1543e23e5	1103	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1104	void IPframe()
nixnax	142:54d1543e23e5	1105	{
nixnax	167:ff8a2d8beeb1	1106	int protocol = ppp.ip->protocol;
nixnax	142:54d1543e23e5	1107	switch (protocol) {
nixnax	142:54d1543e23e5	1108	case 1:
nixnax	142:54d1543e23e5	1109	ICMPpacket();
nixnax	142:54d1543e23e5	1110	break;
nixnax	142:54d1543e23e5	1111	case 2:
nixnax	142:54d1543e23e5	1112	IGMPpacket();
nixnax	142:54d1543e23e5	1113	break;
nixnax	142:54d1543e23e5	1114	case 17:
nixnax	142:54d1543e23e5	1115	UDPpacket();
nixnax	142:54d1543e23e5	1116	break;
nixnax	142:54d1543e23e5	1117	case 6:
nixnax	142:54d1543e23e5	1118	TCPpacket();
nixnax	142:54d1543e23e5	1119	break;
nixnax	142:54d1543e23e5	1120	default:
nixnax	142:54d1543e23e5	1121	otherProtocol();
nixnax	142:54d1543e23e5	1122	}
nixnax	142:54d1543e23e5	1123	}
nixnax	142:54d1543e23e5	1124
nixnax	142:54d1543e23e5	1125	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1126	void LCPconfReq()
nixnax	142:54d1543e23e5	1127	{
nixnax	142:54d1543e23e5	1128	debugPrintf("LCP Config ");
nixnax	175:b4e6f8a6fe00	1129	if ( ppp.lcp->lengthR != __REV16(4) ) {
nixnax	175:b4e6f8a6fe00	1130	ppp.lcp->code=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1131	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1132	sendPppFrame();
nixnax	142:54d1543e23e5	1133	} else {
nixnax	175:b4e6f8a6fe00	1134	ppp.lcp->code=2; // ack zero conf
nixnax	142:54d1543e23e5	1135	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1136	sendPppFrame();
nixnax	142:54d1543e23e5	1137	debugPrintf("LCP Ask\n");
nixnax	175:b4e6f8a6fe00	1138	ppp.lcp->code=1; // request no options
nixnax	144:01d98cf7738e	1139	sendPppFrame();
nixnax	142:54d1543e23e5	1140	}
nixnax	142:54d1543e23e5	1141	}
nixnax	142:54d1543e23e5	1142
nixnax	142:54d1543e23e5	1143	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1144	void LCPconfAck()
nixnax	142:54d1543e23e5	1145	{
nixnax	142:54d1543e23e5	1146	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1147	}
nixnax	142:54d1543e23e5	1148
nixnax	143:c5019f856a56	1149	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1150	void LCPend()
nixnax	142:54d1543e23e5	1151	{
nixnax	175:b4e6f8a6fe00	1152	ppp.lcp->code=6; // end
nixnax	144:01d98cf7738e	1153	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1154	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1155	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1156	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1157	}
nixnax	142:54d1543e23e5	1158
nixnax	142:54d1543e23e5	1159	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1160	void LCPother()
nixnax	142:54d1543e23e5	1161	{
nixnax	142:54d1543e23e5	1162	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1163	dumpPPPFrame();
nixnax	142:54d1543e23e5	1164	}
nixnax	142:54d1543e23e5	1165
nixnax	142:54d1543e23e5	1166	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1167	void LCPframe()
nixnax	142:54d1543e23e5	1168	{
nixnax	175:b4e6f8a6fe00	1169	int code = ppp.lcp->code;
nixnax	142:54d1543e23e5	1170	switch (code) {
nixnax	142:54d1543e23e5	1171	case 1:
nixnax	142:54d1543e23e5	1172	LCPconfReq();
nixnax	142:54d1543e23e5	1173	break; // config request
nixnax	142:54d1543e23e5	1174	case 2:
nixnax	142:54d1543e23e5	1175	LCPconfAck();
nixnax	142:54d1543e23e5	1176	break; // config ack
nixnax	142:54d1543e23e5	1177	case 5:
nixnax	142:54d1543e23e5	1178	LCPend();
nixnax	142:54d1543e23e5	1179	break; // end connection
nixnax	142:54d1543e23e5	1180	default:
nixnax	142:54d1543e23e5	1181	LCPother();
nixnax	142:54d1543e23e5	1182	}
nixnax	142:54d1543e23e5	1183	}
nixnax	142:54d1543e23e5	1184
nixnax	142:54d1543e23e5	1185	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1186	void discardedFrame()
nixnax	142:54d1543e23e5	1187	{
nixnax	142:54d1543e23e5	1188	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	1189	}
nixnax	142:54d1543e23e5	1190
nixnax	142:54d1543e23e5	1191	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1192	void determinePacketType()
nixnax	142:54d1543e23e5	1193	{
nixnax	167:ff8a2d8beeb1	1194	if ( ppp.ppp->address != 0xff ) {
nixnax	167:ff8a2d8beeb1	1195	debugPrintf("Unexpected: PPP address != ff\n");
nixnax	142:54d1543e23e5	1196	return;
nixnax	142:54d1543e23e5	1197	}
nixnax	167:ff8a2d8beeb1	1198	if ( ppp.ppp->control != 3 ) {
nixnax	167:ff8a2d8beeb1	1199	debugPrintf("Unexpected: PPP control != 3\n");
nixnax	142:54d1543e23e5	1200	return;
nixnax	142:54d1543e23e5	1201	}
nixnax	167:ff8a2d8beeb1	1202	unsigned int protocol = __REV16( ppp.ppp->protocolR );
nixnax	167:ff8a2d8beeb1	1203	switch ( protocol ) {
nixnax	167:ff8a2d8beeb1	1204	case 0xc021:
nixnax	142:54d1543e23e5	1205	LCPframe();
nixnax	142:54d1543e23e5	1206	break; // link control
nixnax	167:ff8a2d8beeb1	1207	case 0x8021:
nixnax	142:54d1543e23e5	1208	IPCPframe();
nixnax	142:54d1543e23e5	1209	break; // IP control
nixnax	167:ff8a2d8beeb1	1210	case 0x0021:
nixnax	142:54d1543e23e5	1211	IPframe();
nixnax	142:54d1543e23e5	1212	break; // IP itself
nixnax	142:54d1543e23e5	1213	default:
nixnax	142:54d1543e23e5	1214	discardedFrame();
nixnax	142:54d1543e23e5	1215	}
nixnax	142:54d1543e23e5	1216	}
nixnax	142:54d1543e23e5	1217
nixnax	146:a45f49a2b29c	1218	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1219	void sniff()
nixnax	146:a45f49a2b29c	1220	{
nixnax	146:a45f49a2b29c	1221	if ( pc.readable() ) putsWhileCheckingInput( "Sniff - Char available!\n" ); // if this prints anything it means there is a character in the serial receive buffer
nixnax	146:a45f49a2b29c	1222	}
nixnax	146:a45f49a2b29c	1223
nixnax	142:54d1543e23e5	1224	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1225	void waitForPppFrame()
nixnax	142:54d1543e23e5	1226	{
nixnax	142:54d1543e23e5	1227	while(1) {
nixnax	182:f039ec218c9f	1228	sendUdpData(); // handle received characters from the DEBUG TERMINAL
nixnax	142:54d1543e23e5	1229	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1230	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1231	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1232	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1233	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1234	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1235	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	181:bcfe7fe2142d	1236	ppp.firstFrame=0; // clear first frame flag
nixnax	142:54d1543e23e5	1237	} else {
nixnax	142:54d1543e23e5	1238	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1239	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1240	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1241	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1242	break;
nixnax	142:54d1543e23e5	1243	}
nixnax	142:54d1543e23e5	1244	}
nixnax	142:54d1543e23e5	1245	}
nixnax	142:54d1543e23e5	1246	}
nixnax	142:54d1543e23e5	1247	}
nixnax	142:54d1543e23e5	1248
nixnax	153:7993def8663f	1249	/// Wait for a dial-up modem connect command ("CLIENT") from the host PC, if found, we set ppp.online to true, which will start the IP packet scanner.
nixnax	153:7993def8663f	1250	// Note: a 0x7E in the input stream (ppp start of frame character) will also set ppp.online to true - see checkPc();
nixnax	153:7993def8663f	1251	void waitForPcConnectString()
nixnax	142:54d1543e23e5	1252	{
nixnax	142:54d1543e23e5	1253	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1254	checkPc(); // gather received characters
nixnax	142:54d1543e23e5	1255	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1256	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1257	if (found1 != NULL) {
nixnax	142:54d1543e23e5	1258	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	143:c5019f856a56	1259	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	142:54d1543e23e5	1260	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1261	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1262	checkPc();
nixnax	142:54d1543e23e5	1263	}
nixnax	142:54d1543e23e5	1264	}
nixnax	142:54d1543e23e5	1265	}
nixnax	142:54d1543e23e5	1266
nixnax	144:01d98cf7738e	1267	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1268	void initializePpp()
nixnax	142:54d1543e23e5	1269	{
nixnax	144:01d98cf7738e	1270	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	184:4133f557d4d4	1271	debugPrintf("\x1b[2J\x1b[H\x1b[30m");
nixnax	184:4133f557d4d4	1272	wait_ms(200); // a brief wait so a human can see the reset event
nixnax	184:4133f557d4d4	1273	debugPrintf("mbed PPP-Blinky HTTP & WebSocket server ready :)\n"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax	184:4133f557d4d4	1274
nixnax	179:ba2b2ddd0da5	1275	pppInitStruct(); // initialize all the variables/properties/buffers
nixnax	179:ba2b2ddd0da5	1276	pc.baud(115200); // pc serial port acting as a dial-up modem - for PPP traffic
nixnax	179:ba2b2ddd0da5	1277	pc.attach(&pppReceiveHandler, RawSerial::RxIrq); // set up serial port receive interrupt handler
nixnax	143:c5019f856a56	1278	}

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Repository details

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

The code in this repository is MIT licensed.