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@149:969d98f6fb88, 2017-08-30 (annotated)

Committer:: nixnax
Date:: Wed Aug 30 16:13:34 2017 +0000
Revision:: 149:969d98f6fb88
Parent:: 148:4225c3608b80
Child:: 150:3366bf3d294e

Added swapIpPorts()

Who changed what in which revision?

User	Revision	Line number	New contents of line
nixnax	142:54d1543e23e5	1	// PPP-Blinky - "The Most Basic Internet Of a Thing"
nixnax	142:54d1543e23e5	2	// A Tiny HTTP Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax	142:54d1543e23e5	3	// Receives UDP packets and responds to ping (ICMP Echo requests)
nixnax	142:54d1543e23e5	4	// WebSocket Service - see https://en.wikipedia.org/wiki/WebSocket
nixnax	142:54d1543e23e5	5
nixnax	142:54d1543e23e5	6	// Copyright 2016/2017 Nicolas Nackel aka Nixnax. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nixnax	142:54d1543e23e5	7
nixnax	142:54d1543e23e5	8	// Notes and Instructions
nixnax	142:54d1543e23e5	9	// http://bit.ly/PPP-Blinky-Instructions
nixnax	142:54d1543e23e5	10	// http://bit.ly/win-rasdial-config
nixnax	142:54d1543e23e5	11
nixnax	142:54d1543e23e5	12	// Handy reading material
nixnax	142:54d1543e23e5	13	// https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax	142:54d1543e23e5	14	// https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax	142:54d1543e23e5	15	// http://atari.kensclassics.org/wcomlog.htm
nixnax	142:54d1543e23e5	16
nixnax	142:54d1543e23e5	17	// Handy tools
nixnax	142:54d1543e23e5	18	// https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax	142:54d1543e23e5	19	// https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax	142:54d1543e23e5	20	// http://pingtester.net/ - nice tool for high rate ping testing
nixnax	142:54d1543e23e5	21	// http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax	142:54d1543e23e5	22	// https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax	142:54d1543e23e5	23	// https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax	142:54d1543e23e5	24	// Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax	142:54d1543e23e5	25
nixnax	142:54d1543e23e5	26	// Connecting PPP-Blinky to Linux
nixnax	142:54d1543e23e5	27	// PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax	142:54d1543e23e5	28	// pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax	142:54d1543e23e5	29	// in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax	142:54d1543e23e5	30	// See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax	142:54d1543e23e5	31
nixnax	142:54d1543e23e5	32	// Special pages when PPP-Blinky is running
nixnax	142:54d1543e23e5	33	// 172.10.10.2 root page
nixnax	143:c5019f856a56	34	// 172.10.10.2/x returns a number that increments every time you request a page - this is handy for testing
nixnax	146:a45f49a2b29c	35	// 172.10.10.2/xb also returns a number, but issues a fast refresh meta command. This allows you to use your browser to benchmark page load speed
nixnax	142:54d1543e23e5	36	// 172.10.10.2/ws a simple WebSocket demo
nixnax	142:54d1543e23e5	37	// http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle
nixnax	142:54d1543e23e5	38
nixnax	142:54d1543e23e5	39	// Ok, enough talking, time to check out some code!!
nixnax	142:54d1543e23e5	40
nixnax	142:54d1543e23e5	41	#include "ppp-blinky.h"
nixnax	142:54d1543e23e5	42
nixnax	142:54d1543e23e5	43	// The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax	146:a45f49a2b29c	44	// Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor the debug output.
nixnax	142:54d1543e23e5	45	// Using the second serial port will slow down packet response time
nixnax	142:54d1543e23e5	46	// Note - the LPC11U24 does NOT have a second serial port
nixnax	146:a45f49a2b29c	47
nixnax	148:4225c3608b80	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	142:54d1543e23e5	53	Serial xx(p9, p10); // Second serial port on LPC1768 - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	54	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	142:54d1543e23e5	55	Serial xx(PC_10, PC_11); // Second serial port on NUCLEO boards - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	56	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	57	#error The LPC11U24 does not have a second serial port to use for debugging - change SERIAL_PORT_MONITOR_YES back to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	58	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	142:54d1543e23e5	59	Serial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	142:54d1543e23e5	60	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	61	// change the next line to YOUR target board's second serial port pin definition if it's not present - and if it works, please send it to me - thanks!!!
nixnax	142:54d1543e23e5	62	Serial xx(p9, p10); // change this to YOUR board second serial port pin definition - and please send it to me if it works!!!
nixnax	142:54d1543e23e5	63	#else
nixnax	142:54d1543e23e5	64	#error Add your target board's second serial port here if you want to use debugging - or simply change SERIAL_PORT_MONITOR_YES to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	65	#endif
nixnax	142:54d1543e23e5	66	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we print debug messages */
nixnax	142:54d1543e23e5	67	#define debugPutc(x...) xx.putc(x)
nixnax	142:54d1543e23e5	68	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	69	#else
nixnax	142:54d1543e23e5	70	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	71	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	72	#define debugPutc(x...) {}
nixnax	142:54d1543e23e5	73	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	74	#endif
nixnax	142:54d1543e23e5	75
nixnax	142:54d1543e23e5	76	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	142:54d1543e23e5	77	#define v0 1
nixnax	142:54d1543e23e5	78	#define v1 0
nixnax	142:54d1543e23e5	79	#define v2 0
nixnax	142:54d1543e23e5	80	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	142:54d1543e23e5	81	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	82
nixnax	142:54d1543e23e5	83	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	84	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	85
nixnax	142:54d1543e23e5	86	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	87	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	88	<html>\
nixnax	142:54d1543e23e5	89	<head>\
nixnax	146:a45f49a2b29c	90	<title>mbed PPP-Blinky</title>\r\n\
nixnax	146:a45f49a2b29c	91	<script>\r\n\
nixnax	142:54d1543e23e5	92	window.onload=function(){\
nixnax	142:54d1543e23e5	93	setInterval(function(){function x(){return document.getElementById('w');};\
nixnax	146:a45f49a2b29c	94	x().textContent=parseInt(x().textContent)+1;},100);};\r\n\
nixnax	146:a45f49a2b29c	95	</script>\r\n\
nixnax	142:54d1543e23e5	96	</head>\
nixnax	142:54d1543e23e5	97	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	98	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	99	<h1 id=\"w\">0</h1>\
nixnax	142:54d1543e23e5	100	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	142:54d1543e23e5	101	<h1><a href=\"/ws\">WebSocket Demo</a></h1>\
nixnax	142:54d1543e23e5	102	<h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	103	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	142:54d1543e23e5	104	<h1><a href=\"http://jsfiddle.net/d26cyuh2/\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	105	</body>\
nixnax	146:a45f49a2b29c	106	</html>\r\n"; // size = 644 bytes plus 1 null byte = 645 bytes
nixnax	142:54d1543e23e5	107
nixnax	142:54d1543e23e5	108	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	109	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	110	<html>\
nixnax	142:54d1543e23e5	111	<head>\
nixnax	142:54d1543e23e5	112	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	113	<script>\
nixnax	142:54d1543e23e5	114	window.onload=function(){\
nixnax	142:54d1543e23e5	115	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	116	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	117	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	118	var ctr=0;\
nixnax	142:54d1543e23e5	119	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	120	btn.onclick=function(){\
nixnax	142:54d1543e23e5	121	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	122	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	123	x.onopen=function(){\
nixnax	142:54d1543e23e5	124	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	125	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	126	};\
nixnax	142:54d1543e23e5	127	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	128	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	129	} else {\
nixnax	142:54d1543e23e5	130	x.send(ctr);\
nixnax	142:54d1543e23e5	131	ctr=ctr+1;\
nixnax	142:54d1543e23e5	132	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	133	}\
nixnax	142:54d1543e23e5	134	};\
nixnax	142:54d1543e23e5	135	};\
nixnax	142:54d1543e23e5	136	</script>\
nixnax	142:54d1543e23e5	137	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	138	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	139	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	140	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	141	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	142	</body>\
nixnax	142:54d1543e23e5	143	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	144
nixnax	142:54d1543e23e5	145	// 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	146	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	147	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	148	// See instructions at the top.
nixnax	142:54d1543e23e5	149	// On a typical mbed hardware platform this serial port is a USB virtual com port (VCP) and the USB serial driver is supplied by the board vendor.
nixnax	142:54d1543e23e5	150	BufferedSerial pc(USBTX, USBRX, 100); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	151
nixnax	142:54d1543e23e5	152	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	153
nixnax	142:54d1543e23e5	154	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	155	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	156
nixnax	142:54d1543e23e5	157	/// a structure to keep all our ppp globals in
nixnax	142:54d1543e23e5	158	struct pppType {
nixnax	142:54d1543e23e5	159	int online; // we hunt for a PPP connection if this is zero
nixnax	143:c5019f856a56	160	int hostIP; // ip address of host
nixnax	145:098b6ed2f7f2	161	int fcs; // PPP "frame check sequence" - a 16-bit HDLC-like checksum used in all PPP frames
nixnax	142:54d1543e23e5	162	int ledState; // state of LED1
nixnax	146:a45f49a2b29c	163	int responseCounter;
nixnax	142:54d1543e23e5	164	int firstFrame; // cleared after first frame
nixnax	142:54d1543e23e5	165	struct {
nixnax	142:54d1543e23e5	166	#define RXBUFLEN (1<<11)
nixnax	142:54d1543e23e5	167	// the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 2048 bytes)
nixnax	142:54d1543e23e5	168	char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax	142:54d1543e23e5	169	int head;
nixnax	142:54d1543e23e5	170	int tail;
nixnax	142:54d1543e23e5	171	int rtail;
nixnax	142:54d1543e23e5	172	int buflevel;
nixnax	142:54d1543e23e5	173	} rx; // serial port objects
nixnax	142:54d1543e23e5	174	struct {
nixnax	142:54d1543e23e5	175	int len; // number of bytes in buffer
nixnax	142:54d1543e23e5	176	int crc; // PPP CRC (frame check)
nixnax	142:54d1543e23e5	177	#define PPP_max_size 2500
nixnax	142:54d1543e23e5	178	// we are assuming 1000 bytes more than MTU size of 1500 - due to the PPP encoding of special bytes
nixnax	142:54d1543e23e5	179	char buf[PPP_max_size]; // send and receive buffer large enough for raw, encoded PPP/HDLC frames
nixnax	142:54d1543e23e5	180	} pkt; // ppp buffer objects
nixnax	142:54d1543e23e5	181	struct {
nixnax	142:54d1543e23e5	182	int frameStartIndex; // frame start marker
nixnax	142:54d1543e23e5	183	int frameEndIndex; // frame end marker
nixnax	142:54d1543e23e5	184	} hdlc; // hdlc frame objects
nixnax	142:54d1543e23e5	185	struct {
nixnax	142:54d1543e23e5	186	unsigned int ident; // our IP ident value (outgoing frame count)
nixnax	142:54d1543e23e5	187	} ip; // ip related object
nixnax	142:54d1543e23e5	188	};
nixnax	142:54d1543e23e5	189
nixnax	142:54d1543e23e5	190	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	191
nixnax	142:54d1543e23e5	192	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	193	void pppInitStruct()
nixnax	142:54d1543e23e5	194	{
nixnax	142:54d1543e23e5	195	memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax	142:54d1543e23e5	196	ppp.online=0;
nixnax	142:54d1543e23e5	197	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	198	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	199	ppp.rx.head=0;
nixnax	142:54d1543e23e5	200	ppp.rx.buflevel=0;
nixnax	142:54d1543e23e5	201	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	202	ppp.ip.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	203	ppp.ledState=0;
nixnax	142:54d1543e23e5	204	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	205	ppp.responseCounter=0;
nixnax	142:54d1543e23e5	206	ppp.firstFrame=1;
nixnax	142:54d1543e23e5	207	}
nixnax	142:54d1543e23e5	208
nixnax	142:54d1543e23e5	209	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	210	void led1Toggle()
nixnax	142:54d1543e23e5	211	{
nixnax	142:54d1543e23e5	212	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	213	ppp.ledState++;
nixnax	142:54d1543e23e5	214	}
nixnax	142:54d1543e23e5	215
nixnax	142:54d1543e23e5	216	/// returns 1 after a connect messasge, 0 at startup or after a disconnect message
nixnax	142:54d1543e23e5	217	int connected()
nixnax	142:54d1543e23e5	218	{
nixnax	142:54d1543e23e5	219	return ppp.online;
nixnax	143:c5019f856a56	220	}
nixnax	142:54d1543e23e5	221
nixnax	143:c5019f856a56	222	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	223	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	142:54d1543e23e5	224	void checkPc()
nixnax	142:54d1543e23e5	225	{
nixnax	142:54d1543e23e5	226	char ch;
nixnax	142:54d1543e23e5	227	if ( pc.readable() ) {
nixnax	142:54d1543e23e5	228	int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax	142:54d1543e23e5	229	if ( hd == ppp.rx.rtail ) {
nixnax	142:54d1543e23e5	230	debugPrintf("\nReceive buffer full\n");
nixnax	142:54d1543e23e5	231	return;
nixnax	142:54d1543e23e5	232	}
nixnax	142:54d1543e23e5	233	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	234	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	142:54d1543e23e5	235	if ( ppp.online == 0 ) {
nixnax	142:54d1543e23e5	236	if (ch == 0x7E) {
nixnax	142:54d1543e23e5	237	ppp.online = 1;
nixnax	142:54d1543e23e5	238	}
nixnax	142:54d1543e23e5	239	}
nixnax	142:54d1543e23e5	240	ppp.rx.head = hd; // update head pointer
nixnax	142:54d1543e23e5	241	ppp.rx.buflevel++;
nixnax	142:54d1543e23e5	242	}
nixnax	142:54d1543e23e5	243	}
nixnax	142:54d1543e23e5	244
nixnax	142:54d1543e23e5	245	/// print to debug port while checking for incoming characters
nixnax	142:54d1543e23e5	246	void putcWhileCheckingInput( char outByte )
nixnax	142:54d1543e23e5	247	{
nixnax	142:54d1543e23e5	248	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	249	checkPc();
nixnax	142:54d1543e23e5	250	debugPutc( outByte );
nixnax	142:54d1543e23e5	251	checkPc();
nixnax	142:54d1543e23e5	252	#endif
nixnax	142:54d1543e23e5	253	}
nixnax	142:54d1543e23e5	254
nixnax	142:54d1543e23e5	255	/// puts to debug port while checking the PPP input stream
nixnax	142:54d1543e23e5	256	void putsWhileCheckingInput( char * data )
nixnax	142:54d1543e23e5	257	{
nixnax	142:54d1543e23e5	258	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	259	char * nextChar = data;
nixnax	142:54d1543e23e5	260	while( *nextChar != 0 ) {
nixnax	142:54d1543e23e5	261	putcWhileCheckingInput( *nextChar ); // write one character to debug port while checking input
nixnax	142:54d1543e23e5	262	nextChar++;
nixnax	142:54d1543e23e5	263	}
nixnax	142:54d1543e23e5	264	#endif
nixnax	142:54d1543e23e5	265	}
nixnax	142:54d1543e23e5	266
nixnax	145:098b6ed2f7f2	267	/// Initialize the PPP FCS (frame check sequence) total
nixnax	145:098b6ed2f7f2	268	void fcsReset()
nixnax	142:54d1543e23e5	269	{
nixnax	145:098b6ed2f7f2	270	ppp.fcs=0xffff; // crc restart
nixnax	142:54d1543e23e5	271	}
nixnax	142:54d1543e23e5	272
nixnax	145:098b6ed2f7f2	273	/// update the cumulative PPP FCS (frame check sequence)
nixnax	145:098b6ed2f7f2	274	void fcsDo(int x)
nixnax	142:54d1543e23e5	275	{
nixnax	142:54d1543e23e5	276	for (int i=0; i<8; i++) {
nixnax	145:098b6ed2f7f2	277	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1; // crc calculator
nixnax	142:54d1543e23e5	278	x>>=1;
nixnax	142:54d1543e23e5	279	}
nixnax	142:54d1543e23e5	280	checkPc(); // handle input
nixnax	142:54d1543e23e5	281	}
nixnax	142:54d1543e23e5	282
nixnax	145:098b6ed2f7f2	283	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	284	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	285	{
nixnax	145:098b6ed2f7f2	286	fcsReset();
nixnax	145:098b6ed2f7f2	287	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	288	return ppp.fcs;
nixnax	142:54d1543e23e5	289	}
nixnax	142:54d1543e23e5	290
nixnax	142:54d1543e23e5	291	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	292	int pc_getBuf()
nixnax	142:54d1543e23e5	293	{
nixnax	142:54d1543e23e5	294	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	142:54d1543e23e5	295	ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax	142:54d1543e23e5	296	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	297	return x;
nixnax	142:54d1543e23e5	298	}
nixnax	142:54d1543e23e5	299
nixnax	142:54d1543e23e5	300	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	301	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	302	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	142:54d1543e23e5	303	/// In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	304	void dumpPPPFrame()
nixnax	142:54d1543e23e5	305	{
nixnax	142:54d1543e23e5	306	char pbuf[30];
nixnax	142:54d1543e23e5	307	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	308	checkPc();
nixnax	142:54d1543e23e5	309	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	142:54d1543e23e5	310	checkPc();
nixnax	142:54d1543e23e5	311	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	312	}
nixnax	142:54d1543e23e5	313	checkPc();
nixnax	142:54d1543e23e5	314	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	142:54d1543e23e5	315	checkPc();
nixnax	142:54d1543e23e5	316	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	317	}
nixnax	142:54d1543e23e5	318
nixnax	142:54d1543e23e5	319	/// Process a received PPP frame
nixnax	142:54d1543e23e5	320	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	321	{
nixnax	142:54d1543e23e5	322	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	323	if(start==end) {
nixnax	142:54d1543e23e5	324	return; // empty frame
nixnax	142:54d1543e23e5	325	}
nixnax	145:098b6ed2f7f2	326	fcsReset();
nixnax	142:54d1543e23e5	327	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	328	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	329	int unstuff=0;
nixnax	142:54d1543e23e5	330	int idx = start;
nixnax	142:54d1543e23e5	331	while(1) {
nixnax	142:54d1543e23e5	332	checkPc();
nixnax	142:54d1543e23e5	333	if (unstuff==0) {
nixnax	142:54d1543e23e5	334	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	335	else {
nixnax	142:54d1543e23e5	336	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	337	ppp.pkt.len++;
nixnax	142:54d1543e23e5	338	dest++;
nixnax	145:098b6ed2f7f2	339	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	340	}
nixnax	142:54d1543e23e5	341	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	342	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	343	ppp.pkt.len++;
nixnax	142:54d1543e23e5	344	dest++;
nixnax	145:098b6ed2f7f2	345	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	346	unstuff=0;
nixnax	142:54d1543e23e5	347	}
nixnax	142:54d1543e23e5	348	idx = (idx+1) & (RXBUFLEN-1);
nixnax	142:54d1543e23e5	349	if (idx == end) break;
nixnax	142:54d1543e23e5	350	}
nixnax	145:098b6ed2f7f2	351	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	352	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	353	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	354	determinePacketType();
nixnax	142:54d1543e23e5	355	} else {
nixnax	142:54d1543e23e5	356	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	357	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	358	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	359	checkPc();
nixnax	142:54d1543e23e5	360	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	142:54d1543e23e5	361	checkPc();
nixnax	142:54d1543e23e5	362	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	363	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	364	#endif
nixnax	142:54d1543e23e5	365	}
nixnax	142:54d1543e23e5	366	}
nixnax	142:54d1543e23e5	367
nixnax	142:54d1543e23e5	368	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	369	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	370	{
nixnax	142:54d1543e23e5	371	checkPc(); // check input
nixnax	142:54d1543e23e5	372	pc.putc(ch);
nixnax	142:54d1543e23e5	373	checkPc();
nixnax	142:54d1543e23e5	374	}
nixnax	142:54d1543e23e5	375
nixnax	142:54d1543e23e5	376	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	377	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	378	{
nixnax	142:54d1543e23e5	379	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	380	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	381	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	382	} else {
nixnax	142:54d1543e23e5	383	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	384	}
nixnax	142:54d1543e23e5	385	}
nixnax	142:54d1543e23e5	386
nixnax	142:54d1543e23e5	387	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	388	void sendPppFrame()
nixnax	143:c5019f856a56	389	{
nixnax	145:098b6ed2f7f2	390	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	391	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	392	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	393	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	394	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	395	wait_us(86); // wait one character time
nixnax	142:54d1543e23e5	396	checkPc();
nixnax	142:54d1543e23e5	397	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	398	}
nixnax	142:54d1543e23e5	399	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	400	}
nixnax	142:54d1543e23e5	401
nixnax	143:c5019f856a56	402	/// 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	403	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	404	{
nixnax	143:c5019f856a56	405	int result=0;
nixnax	143:c5019f856a56	406	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	407	return result;
nixnax	143:c5019f856a56	408	}
nixnax	143:c5019f856a56	409
nixnax	142:54d1543e23e5	410	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	411	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	412	{
nixnax	142:54d1543e23e5	413	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	143:c5019f856a56	414	if(ppp.pkt.buf[8]==3) {
nixnax	143:c5019f856a56	415	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	143:c5019f856a56	416	debugPrintf("Host IP = %d.%d.%d.%d (%08x)\n", ppp.pkt.buf[10],ppp.pkt.buf[11],ppp.pkt.buf[12],ppp.pkt.buf[13],ppp.hostIP);
nixnax	143:c5019f856a56	417	}
nixnax	143:c5019f856a56	418
nixnax	142:54d1543e23e5	419	ppp.pkt.buf[4]=2; // change code to ack
nixnax	144:01d98cf7738e	420	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	421
nixnax	142:54d1543e23e5	422	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	142:54d1543e23e5	423	ppp.pkt.buf[4]=1; // change code to request
nixnax	142:54d1543e23e5	424	ppp.pkt.buf[7]=4; // no options in this request
nixnax	142:54d1543e23e5	425	ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	426	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	427	}
nixnax	142:54d1543e23e5	428
nixnax	142:54d1543e23e5	429	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	430	void ipcpAckHandler()
nixnax	142:54d1543e23e5	431	{
nixnax	142:54d1543e23e5	432	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	433	}
nixnax	142:54d1543e23e5	434
nixnax	143:c5019f856a56	435	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	436	/// 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	437	void ipcpNackHandler()
nixnax	142:54d1543e23e5	438	{
nixnax	146:a45f49a2b29c	439	debugPrintf("Their IPCP Nack\n");
nixnax	142:54d1543e23e5	440	if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax	142:54d1543e23e5	441	ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	442	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	443	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	444	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	445	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	446	}
nixnax	142:54d1543e23e5	447	}
nixnax	142:54d1543e23e5	448
nixnax	142:54d1543e23e5	449	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	450	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	451	{
nixnax	142:54d1543e23e5	452	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	453	}
nixnax	142:54d1543e23e5	454
nixnax	142:54d1543e23e5	455	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	456	void IPCPframe()
nixnax	142:54d1543e23e5	457	{
nixnax	142:54d1543e23e5	458	int code = ppp.pkt.buf[4]; // packet type is here
nixnax	142:54d1543e23e5	459	switch (code) {
nixnax	142:54d1543e23e5	460	case 1:
nixnax	142:54d1543e23e5	461	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	462	break;
nixnax	142:54d1543e23e5	463	case 2:
nixnax	142:54d1543e23e5	464	ipcpAckHandler();
nixnax	142:54d1543e23e5	465	break;
nixnax	142:54d1543e23e5	466	case 3:
nixnax	142:54d1543e23e5	467	ipcpNackHandler();
nixnax	142:54d1543e23e5	468	break;
nixnax	142:54d1543e23e5	469	default:
nixnax	142:54d1543e23e5	470	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	471	}
nixnax	142:54d1543e23e5	472	}
nixnax	142:54d1543e23e5	473
nixnax	142:54d1543e23e5	474	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	142:54d1543e23e5	475	unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax	142:54d1543e23e5	476	{
nixnax	142:54d1543e23e5	477	unsigned int i,hi,lo,sum;
nixnax	142:54d1543e23e5	478	unsigned char placeHolder;
nixnax	142:54d1543e23e5	479	if (len&1) {
nixnax	142:54d1543e23e5	480	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	481	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	482	}
nixnax	142:54d1543e23e5	483	sum=0;
nixnax	142:54d1543e23e5	484	i=0;
nixnax	142:54d1543e23e5	485	while ( i<len ) {
nixnax	142:54d1543e23e5	486	checkPc();
nixnax	142:54d1543e23e5	487	hi = ptr[i++];
nixnax	142:54d1543e23e5	488	lo = ptr[i++];
nixnax	142:54d1543e23e5	489	sum = sum + ( (hi<<8) \| lo );
nixnax	142:54d1543e23e5	490	}
nixnax	142:54d1543e23e5	491	if (len&1) {
nixnax	142:54d1543e23e5	492	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	493	}
nixnax	142:54d1543e23e5	494	sum = (sum & 0xffff) + (sum>>16);
nixnax	142:54d1543e23e5	495	sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax	142:54d1543e23e5	496	return ~sum;
nixnax	142:54d1543e23e5	497	}
nixnax	142:54d1543e23e5	498
nixnax	142:54d1543e23e5	499	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	500	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	501	{
nixnax	146:a45f49a2b29c	502	ppp.pkt.buf[4+10]=0; // zero the checsum in the IP header
nixnax	146:a45f49a2b29c	503	ppp.pkt.buf[4+11]=0; // zero the checksum in the IP header
nixnax	146:a45f49a2b29c	504	int len =(ppp.pkt.buf[4]&0xf)*4; // length of IP header in bytes
nixnax	146:a45f49a2b29c	505	char * ptr = ppp.pkt.buf+4; // start of IP packet
nixnax	142:54d1543e23e5	506	int sum=0;
nixnax	142:54d1543e23e5	507	for (int i=0; i<len/2; i++) {
nixnax	142:54d1543e23e5	508	int hi = *ptr;
nixnax	142:54d1543e23e5	509	ptr++;
nixnax	142:54d1543e23e5	510	int lo = *ptr;
nixnax	142:54d1543e23e5	511	ptr++;
nixnax	142:54d1543e23e5	512	int val = ( lo & 0xff ) \| ( (hi<<8) & 0xff00 );
nixnax	142:54d1543e23e5	513	sum = sum + val;
nixnax	142:54d1543e23e5	514	checkPc();
nixnax	142:54d1543e23e5	515	}
nixnax	142:54d1543e23e5	516	sum = sum + (sum>>16);
nixnax	142:54d1543e23e5	517	sum = ~sum;
nixnax	146:a45f49a2b29c	518	ppp.pkt.buf[4+10]= (sum>>8);
nixnax	146:a45f49a2b29c	519	ppp.pkt.buf[4+11]= (sum );
nixnax	146:a45f49a2b29c	520	}
nixnax	146:a45f49a2b29c	521
nixnax	147:0f40005cbc5f	522	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	523	void swapIpAddresses()
nixnax	147:0f40005cbc5f	524	{
nixnax	147:0f40005cbc5f	525	char tempHold[4];
nixnax	147:0f40005cbc5f	526	memcpy(tempHold, ppp.pkt.buf+16,4); // tempHold <- source IP
nixnax	147:0f40005cbc5f	527	memcpy(ppp.pkt.buf+16, ppp.pkt.buf+20,4); // source <- dest
nixnax	147:0f40005cbc5f	528	memcpy(ppp.pkt.buf+20, tempHold,4); // dest <- tempHold
nixnax	147:0f40005cbc5f	529	}
nixnax	147:0f40005cbc5f	530
nixnax	149:969d98f6fb88	531	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	532	void swapIpPorts()
nixnax	149:969d98f6fb88	533	{
nixnax	149:969d98f6fb88	534	int headerSizeIP = 4*(ppp.pkt.buf[4]&0xf); // calculate size of IP header
nixnax	149:969d98f6fb88	535	char * ipSrcPort = 4 + ppp.pkt.buf + headerSizeIP + 0; // ip source port location
nixnax	149:969d98f6fb88	536	char * ipDstPort = 4 + ppp.pkt.buf + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	537	char tempHold[2];
nixnax	149:969d98f6fb88	538	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	539	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	540	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	541	}
nixnax	149:969d98f6fb88	542
nixnax	146:a45f49a2b29c	543	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	544	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	545	void UDPpacket()
nixnax	146:a45f49a2b29c	546	{
nixnax	146:a45f49a2b29c	547	char * ipHeader = ppp.pkt.buf+4; // udp packet start
nixnax	146:a45f49a2b29c	548	char * ipSizeBuf = ipHeader+2; // size of IP packet
nixnax	146:a45f49a2b29c	549	int headerSizeIP = 4*(ipHeader[0]&0xf); // size of IP header
nixnax	146:a45f49a2b29c	550	char * udpHeader = ipHeader + headerSizeIP; // udp info start
nixnax	146:a45f49a2b29c	551	char * udpLen = udpHeader+4; // udp data length
nixnax	146:a45f49a2b29c	552	char * udpCheckSum = udpHeader+6; // udp checksum
nixnax	146:a45f49a2b29c	553	char * udpData = udpHeader+8; // start of UDP data
nixnax	146:a45f49a2b29c	554	int udpLength = ((udpLen[0]<<8) \| udpLen[1]); // size of udp packet
nixnax	146:a45f49a2b29c	555	int udpDataSize = udpLength - 8; // size of udp data
nixnax	147:0f40005cbc5f	556
nixnax	146:a45f49a2b29c	557	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	147:0f40005cbc5f	558	char * srcIP = ipHeader+12; // IP source
nixnax	147:0f40005cbc5f	559	char * dstIP = ipHeader+16; // IP destination
nixnax	149:969d98f6fb88	560	char * udpSrcPort = udpHeader+0; // source port
nixnax	149:969d98f6fb88	561	char * udpDstPort = udpHeader+2; // destination port
nixnax	146:a45f49a2b29c	562	int udpSrc = (udpSrcPort[0]<<8)\|udpSrcPort[1]; // integer of UDP source port
nixnax	146:a45f49a2b29c	563	int udpDst = (udpDstPort[0]<<8)\|udpDstPort[1]; // integer of UDP dest port
nixnax	146:a45f49a2b29c	564	if(v0) debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrc);
nixnax	146:a45f49a2b29c	565	if(v0) debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDst);
nixnax	146:a45f49a2b29c	566	if(v0) debugPrintf("Len %03d", udpLength);
nixnax	146:a45f49a2b29c	567	if (v1) {
nixnax	146:a45f49a2b29c	568	int printSize = udpLength-8;
nixnax	146:a45f49a2b29c	569	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	570	for (int i=0; i<printSize; i++) {
nixnax	146:a45f49a2b29c	571	char ch = udpData[i];
nixnax	146:a45f49a2b29c	572	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	573	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	574	} else {
nixnax	146:a45f49a2b29c	575	debugPrintf("_");
nixnax	146:a45f49a2b29c	576	}
nixnax	146:a45f49a2b29c	577	}
nixnax	146:a45f49a2b29c	578	}
nixnax	146:a45f49a2b29c	579	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	580	#endif
nixnax	146:a45f49a2b29c	581	int echoFound = !strncmp(udpData,"echo ",5); // true if UDP message starts with "echo "
nixnax	146:a45f49a2b29c	582	int testFound = !strncmp(udpData,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	583	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	147:0f40005cbc5f	584	swapIpAddresses(); // swap IP source and destination
nixnax	149:969d98f6fb88	585	swapIpPorts(); // swap IP source and destination ports
nixnax	146:a45f49a2b29c	586	if (echoFound) {
nixnax	146:a45f49a2b29c	587	memcpy(udpData,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	146:a45f49a2b29c	588	char endString[] = "} UDP Server: PPP-Blinky\n"; // an appendix
nixnax	146:a45f49a2b29c	589	memcpy(udpData+udpLength-8,endString,sizeof(endString)-1); // add endstring size to the UDP message
nixnax	146:a45f49a2b29c	590	udpDataSize = udpDataSize + sizeof(endString)-1; // update udp data size with the size of the appendix
nixnax	146:a45f49a2b29c	591	}
nixnax	146:a45f49a2b29c	592	if (testFound) {
nixnax	146:a45f49a2b29c	593	char udpResponse[50];
nixnax	146:a45f49a2b29c	594	int n = 0;
nixnax	146:a45f49a2b29c	595	n = n+sprintf(udpResponse+n,"Response count %d\n",ppp.responseCounter++);
nixnax	146:a45f49a2b29c	596	memcpy(udpData,udpResponse,n); // copy response to the UDP data area
nixnax	146:a45f49a2b29c	597	udpDataSize = n; // new udp data size
nixnax	146:a45f49a2b29c	598	}
nixnax	146:a45f49a2b29c	599	udpLength = udpDataSize+8; // update udp packet length
nixnax	146:a45f49a2b29c	600	int ipSize = headerSizeIP + udpLength; // update ip packet length
nixnax	146:a45f49a2b29c	601	ppp.pkt.len = ipSize+2+4; // update ppp packet length
nixnax	146:a45f49a2b29c	602	udpLen[0] = udpLength>>8;
nixnax	146:a45f49a2b29c	603	udpLen[1] = udpLength; // update UDP length
nixnax	146:a45f49a2b29c	604	ipSizeBuf[0] = ipSize>>8;
nixnax	146:a45f49a2b29c	605	ipSizeBuf[1] = ipSize; // update IP length
nixnax	146:a45f49a2b29c	606	IpHeaderCheckSum(); // update IP header checksum
nixnax	146:a45f49a2b29c	607	memset(udpCheckSum,0,2); // we don't yet recompute the checksum (it's optional), so have to zero it
nixnax	146:a45f49a2b29c	608	sendPppFrame(); // send the UDP message back
nixnax	146:a45f49a2b29c	609	}
nixnax	142:54d1543e23e5	610	}
nixnax	142:54d1543e23e5	611
nixnax	142:54d1543e23e5	612	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	613	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	614	{
nixnax	142:54d1543e23e5	615	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	616	char * pktLen = ipPkt+2;
nixnax	142:54d1543e23e5	617	int packetLength = (pktLen[0]<<8) \| pktLen[1]; // icmp packet length
nixnax	142:54d1543e23e5	618	int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax	142:54d1543e23e5	619	char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax	142:54d1543e23e5	620	char * icmpSum = icmpType+2; // icmp checksum
nixnax	142:54d1543e23e5	621	#define ICMP_TYPE_PING_REQUEST 8
nixnax	142:54d1543e23e5	622	if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax	142:54d1543e23e5	623	char * ipTTL = ipPkt+8; // time to live
nixnax	147:0f40005cbc5f	624	ipTTL[0]--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	625	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	626	char * srcAdr = ipPkt+12;
nixnax	142:54d1543e23e5	627	char * dstAdr = ipPkt+16;
nixnax	142:54d1543e23e5	628	int icmpIdent = (icmpType[4]<<8)\|icmpType[5];
nixnax	142:54d1543e23e5	629	int icmpSequence = (icmpType[6]<<8)\|icmpType[7];
nixnax	142:54d1543e23e5	630	if(1) {
nixnax	142:54d1543e23e5	631	char pbuf[50];
nixnax	142:54d1543e23e5	632	checkPc();
nixnax	142:54d1543e23e5	633	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	634	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	635	checkPc();
nixnax	142:54d1543e23e5	636	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	142:54d1543e23e5	637	checkPc();
nixnax	142:54d1543e23e5	638	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	639	}
nixnax	142:54d1543e23e5	640	#endif
nixnax	147:0f40005cbc5f	641	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	642	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	643	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	142:54d1543e23e5	644	icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	142:54d1543e23e5	645	icmpSum[0]=0;
nixnax	142:54d1543e23e5	646	icmpSum[1]=0; // zero the checksum for recalculation
nixnax	142:54d1543e23e5	647	int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax	142:54d1543e23e5	648	unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax	142:54d1543e23e5	649	icmpSum[0]=(sum>>8)&0xff;
nixnax	142:54d1543e23e5	650	icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax	142:54d1543e23e5	651
nixnax	142:54d1543e23e5	652	int printSize = icmpLength-8; // exclude size of icmp header
nixnax	142:54d1543e23e5	653	char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax	142:54d1543e23e5	654	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	655	if (0) {
nixnax	142:54d1543e23e5	656	for (int i=0; i<printSize; i++) {
nixnax	142:54d1543e23e5	657	char ch = icmpData[i];
nixnax	142:54d1543e23e5	658	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	659	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	660	} else {
nixnax	142:54d1543e23e5	661	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	662	}
nixnax	142:54d1543e23e5	663	}
nixnax	142:54d1543e23e5	664	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	665	}
nixnax	144:01d98cf7738e	666	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	667	} else {
nixnax	142:54d1543e23e5	668	if (v0) {
nixnax	142:54d1543e23e5	669	debugPrintf("ICMP type=%d \n", icmpType[0]);
nixnax	142:54d1543e23e5	670	}
nixnax	142:54d1543e23e5	671	}
nixnax	142:54d1543e23e5	672	}
nixnax	142:54d1543e23e5	673
nixnax	142:54d1543e23e5	674	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	675	void IGMPpacket()
nixnax	142:54d1543e23e5	676	{
nixnax	142:54d1543e23e5	677	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	678	}
nixnax	142:54d1543e23e5	679
nixnax	142:54d1543e23e5	680	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	681	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	682	{
nixnax	142:54d1543e23e5	683	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	684	checkPc(); // we are expecting the first character of the next packet
nixnax	142:54d1543e23e5	685	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	686	char * ident = ipPkt+4; // 2 bytes
nixnax	142:54d1543e23e5	687	#ifdef UNUSED_IP_VARIABLES
nixnax	142:54d1543e23e5	688	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	142:54d1543e23e5	689	char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	690	char * version = ipPkt; // top 4 bits
nixnax	142:54d1543e23e5	691	char * ihl = ipPkt; // bottom 4 bits
nixnax	142:54d1543e23e5	692	char * dscp = ipPkt+1; // top 6 bits
nixnax	142:54d1543e23e5	693	char * ecn = ipPkt+1; // lower 2 bits
nixnax	142:54d1543e23e5	694	char * pktLen = ipPkt+2; // 2 bytes
nixnax	142:54d1543e23e5	695	char * flags = ipPkt+6; // 2 bits
nixnax	142:54d1543e23e5	696	char * ttl = ipPkt+8; // 1 byte
nixnax	142:54d1543e23e5	697	char * protocol = ipPkt+9; // 1 byte
nixnax	142:54d1543e23e5	698	char * headercheck= ipPkt+10; // 2 bytes
nixnax	142:54d1543e23e5	699	int versionIP = (version[0]>>4)&0xf;
nixnax	142:54d1543e23e5	700	int headerSizeIP = (ihl[0]&0xf)*4;
nixnax	142:54d1543e23e5	701	int dscpIP = (dscp[0]>>2)&0x3f;
nixnax	142:54d1543e23e5	702	int ecnIP = ecn[0]&3;
nixnax	142:54d1543e23e5	703	int packetLength = (pktLen[0]<<8)\|pktLen[1]; // ip total packet length
nixnax	142:54d1543e23e5	704	int flagsIP = flags[0]>>14&3;
nixnax	142:54d1543e23e5	705	int ttlIP = ttl[0];
nixnax	142:54d1543e23e5	706	int protocolIP = protocol[0];
nixnax	142:54d1543e23e5	707	unsigned int checksumIP = (headercheck[0]<<8)\|headercheck[1];
nixnax	142:54d1543e23e5	708	#endif
nixnax	142:54d1543e23e5	709	int IPv4Id = (ident[0]<<8)\|ident[1];
nixnax	142:54d1543e23e5	710	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	711	int n=0;
nixnax	142:54d1543e23e5	712	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	713	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	714	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	715	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	716	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	142:54d1543e23e5	717	char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	718	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	719	#endif
nixnax	142:54d1543e23e5	720	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	721	#ifndef TCP_HEADER_DUMP_YES
nixnax	142:54d1543e23e5	722	putsWhileCheckingInput('\x1b[30m\n'); // there is no TCP header dump, so terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	723	#endif
nixnax	142:54d1543e23e5	724	#endif
nixnax	142:54d1543e23e5	725	}
nixnax	142:54d1543e23e5	726
nixnax	142:54d1543e23e5	727	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	728	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	729	{
nixnax	142:54d1543e23e5	730	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	731	int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax	142:54d1543e23e5	732	char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax	142:54d1543e23e5	733	char * seqtcp = tcpStart + 4; // 4 bytes
nixnax	142:54d1543e23e5	734	char * acktcp = tcpStart + 8; // 4 bytes
nixnax	142:54d1543e23e5	735	char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax	142:54d1543e23e5	736	unsigned int seq = (seqtcp[0]<<24)\|(seqtcp[1]<<16)\|(seqtcp[2]<<8)\|(seqtcp[3]);
nixnax	142:54d1543e23e5	737	unsigned int ack = (acktcp[0]<<24)\|(acktcp[1]<<16)\|(acktcp[2]<<8)\|(acktcp[3]);
nixnax	142:54d1543e23e5	738	if (seq && ack) {} // shut up the compiler about unused variables
nixnax	142:54d1543e23e5	739	int flags = ((flagbitstcp[0]&1)<<8)\|flagbitstcp[1];
nixnax	142:54d1543e23e5	740	char flagInfo[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	741	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	742	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	743	memset(flagInfo,'.', 8); // fill string with "........"
nixnax	142:54d1543e23e5	744	flagInfo[8]=0; // null terminate string
nixnax	142:54d1543e23e5	745	if (flags & (1<<0)) flagInfo[7]='F';
nixnax	142:54d1543e23e5	746	if (flags & (1<<1)) flagInfo[6]='S';
nixnax	142:54d1543e23e5	747	if (flags & (1<<2)) flagInfo[5]='R';
nixnax	142:54d1543e23e5	748	if (flags & (1<<3)) flagInfo[4]='P';
nixnax	142:54d1543e23e5	749	if (flags & (1<<4)) flagInfo[3]='A';
nixnax	142:54d1543e23e5	750	if (flags & (1<<5)) flagInfo[2]='U';
nixnax	142:54d1543e23e5	751	if (flags & (1<<6)) flagInfo[1]='E';
nixnax	142:54d1543e23e5	752	if (flags & (1<<7)) flagInfo[0]='C';
nixnax	142:54d1543e23e5	753	#else
nixnax	142:54d1543e23e5	754	if (flags & (1<<4)) flagInfo[0]='A'; // choose the most important flag to print
nixnax	142:54d1543e23e5	755	if (flags & (1<<1)) flagInfo[0]='S';
nixnax	142:54d1543e23e5	756	if (flags & (1<<0)) flagInfo[0]='F';
nixnax	142:54d1543e23e5	757	if (flags & (1<<3)) flagInfo[0]='P';
nixnax	142:54d1543e23e5	758	if (flags & (1<<2)) flagInfo[0]='R';
nixnax	142:54d1543e23e5	759	flagInfo[1]=0; // ' '
nixnax	142:54d1543e23e5	760	flagInfo[2]=0;
nixnax	142:54d1543e23e5	761	#endif
nixnax	142:54d1543e23e5	762	putsWhileCheckingInput( flagInfo );
nixnax	142:54d1543e23e5	763	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	764	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	765	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	142:54d1543e23e5	766	#endif
nixnax	142:54d1543e23e5	767	if( outGoing && ( flags == 0x11 ) ) { // ACK/FIN - if this is an outgoing ACK/FIN its the end of a tcp conversation
nixnax	142:54d1543e23e5	768	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end of an HTTP the conversation
nixnax	142:54d1543e23e5	769	}
nixnax	142:54d1543e23e5	770	#endif
nixnax	142:54d1543e23e5	771	}
nixnax	142:54d1543e23e5	772
nixnax	143:c5019f856a56	773	/// Encode a buffer in base-64
nixnax	142:54d1543e23e5	774	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	775	{
nixnax	142:54d1543e23e5	776	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	777	int i,j,a,b,c;
nixnax	142:54d1543e23e5	778	i=0;
nixnax	142:54d1543e23e5	779	j=0;
nixnax	142:54d1543e23e5	780	while(1) {
nixnax	142:54d1543e23e5	781	if (i<len) {
nixnax	142:54d1543e23e5	782	a = in[i++];
nixnax	142:54d1543e23e5	783	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	784	} else break;
nixnax	142:54d1543e23e5	785	if (i<len) {
nixnax	142:54d1543e23e5	786	b = in[i++];
nixnax	142:54d1543e23e5	787	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	788	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	789	} else out[j++] = '=';
nixnax	142:54d1543e23e5	790	if (i<len) {
nixnax	142:54d1543e23e5	791	c = in[i++];
nixnax	142:54d1543e23e5	792	j--;
nixnax	142:54d1543e23e5	793	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	794	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	795	} else out[j++] = '=';
nixnax	142:54d1543e23e5	796	}
nixnax	142:54d1543e23e5	797	out[j]=0;
nixnax	142:54d1543e23e5	798	}
nixnax	142:54d1543e23e5	799
nixnax	142:54d1543e23e5	800	/// handle a request for an http websocket
nixnax	142:54d1543e23e5	801	/// 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	802	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	803	{
nixnax	142:54d1543e23e5	804	int n=0; // byte counter
nixnax	142:54d1543e23e5	805	char * key = strstr(dataStart, "Sec-WebSocket-Key: "); // search for the key in the payload
nixnax	142:54d1543e23e5	806	if (key != NULL) {
nixnax	142:54d1543e23e5	807	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	142:54d1543e23e5	808	char challenge [70];
nixnax	142:54d1543e23e5	809	strncpy(challenge,key+19,70); // a local buffer
nixnax	142:54d1543e23e5	810	*strchr(challenge,'\r')=0; // insert null so we can use sprintf
nixnax	142:54d1543e23e5	811	strncat(challenge,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11",70); // append websocket gui code
nixnax	142:54d1543e23e5	812	char shaOutput [20]; // sha1 output
nixnax	142:54d1543e23e5	813	sha1( shaOutput, challenge, strlen(challenge));
nixnax	142:54d1543e23e5	814	char encOut[50];
nixnax	142:54d1543e23e5	815	enc64( shaOutput, encOut, 20);
nixnax	142:54d1543e23e5	816	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	817	char * version = challenge;
nixnax	142:54d1543e23e5	818	strncpy(version, versionstring,70); // copy version string
nixnax	142:54d1543e23e5	819	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	820	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	821	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	822	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	823	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	824	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	825	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	826	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	827	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	828	}
nixnax	142:54d1543e23e5	829	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	830	}
nixnax	142:54d1543e23e5	831
nixnax	142:54d1543e23e5	832	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	833	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	834	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	835	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	836	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	837
nixnax	142:54d1543e23e5	838	/// respond to an HTTP request
nixnax	142:54d1543e23e5	839	int httpResponse(char * dataStart)
nixnax	142:54d1543e23e5	840	{
nixnax	142:54d1543e23e5	841	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	842	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	142:54d1543e23e5	843	if (n>0) return n; // if it's a WebSocket we already have the response, so return
nixnax	142:54d1543e23e5	844
nixnax	142:54d1543e23e5	845	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	846	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	847	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	142:54d1543e23e5	848
nixnax	146:a45f49a2b29c	849	ppp.responseCounter++; // increment the number of frames we have made
nixnax	142:54d1543e23e5	850
nixnax	142:54d1543e23e5	851	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	852	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	853	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	854	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	855	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	142:54d1543e23e5	856	if( (httpGetRoot==0) \|\| (httpGetx==0) ) {
nixnax	142:54d1543e23e5	857	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	858	} else {
nixnax	142:54d1543e23e5	859	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	860	}
nixnax	142:54d1543e23e5	861	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	862	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	863	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	864	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	142:54d1543e23e5	865	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	866	nHeader=n; // size of HTTP header
nixnax	142:54d1543e23e5	867	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	868	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	869	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	870	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	142:54d1543e23e5	871	} else if ( (httpGet5 == 'w') && (httpGet6 == 's') ) { // "ws" is a special page for websocket demo
nixnax	142:54d1543e23e5	872	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	873	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	142:54d1543e23e5	874	} else {
nixnax	142:54d1543e23e5	875	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	876
nixnax	142:54d1543e23e5	877	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	878	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	879	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	880	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	881	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	882	#else
nixnax	142:54d1543e23e5	883	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	142:54d1543e23e5	884	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	885	}
nixnax	142:54d1543e23e5	886	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	887	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	888	#endif
nixnax	142:54d1543e23e5	889	} else {
nixnax	142:54d1543e23e5	890	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	891	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	892	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	893	}
nixnax	142:54d1543e23e5	894	}
nixnax	142:54d1543e23e5	895	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	896	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	897	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	898	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	899	return n; // total byte size of our response
nixnax	142:54d1543e23e5	900	}
nixnax	142:54d1543e23e5	901
nixnax	142:54d1543e23e5	902	/// handle TCP data that is not an HTTP get
nixnax	142:54d1543e23e5	903	/// this is the response if we have TCP data but it's not an HTTP GET
nixnax	142:54d1543e23e5	904	/// this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax	142:54d1543e23e5	905	/// this could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	906	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	907	{
nixnax	142:54d1543e23e5	908	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	909	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	142:54d1543e23e5	910	// this is most likely a websocket push message. you get this when you enter this in your browser console: x.send("my message");
nixnax	142:54d1543e23e5	911	if (0) putsWhileCheckingInput( "Got data from websocket send()\n" );
nixnax	142:54d1543e23e5	912
nixnax	142:54d1543e23e5	913	// for now we simply echo the websocket data back to the client - the client should therefore see an onmessage event
nixnax	142:54d1543e23e5	914	// to display the echoed data in your browser, enter the following into the browser console: x.onmessage = function(msg){ console.log( msg.data ); }
nixnax	142:54d1543e23e5	915	if (1) {
nixnax	142:54d1543e23e5	916	char mask [4];
nixnax	142:54d1543e23e5	917	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	142:54d1543e23e5	918	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	142:54d1543e23e5	919	if((dataStart[1]&0x80)==0x80) // test if the mask bit is set, which means all data is xor'ed with the mask
nixnax	142:54d1543e23e5	920	for (int i=0; i<websocketMessageSize; i++) dataStart[i+6]^= mask[i%4]; // unmask each byte with one of the mask bytes
nixnax	142:54d1543e23e5	921	dataStart[1] = len-2; // add four extra bytes to the message length because we don't use mask bytes for the send
nixnax	142:54d1543e23e5	922	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	142:54d1543e23e5	923	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	924	}
nixnax	142:54d1543e23e5	925	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	926	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	927	dataStart[1]=0; // we don't have mask bytes on
nixnax	142:54d1543e23e5	928	} else if (v1) putsWhileCheckingInput("TCP data received\n");
nixnax	142:54d1543e23e5	929	return n; // total byte size of our response
nixnax	142:54d1543e23e5	930	}
nixnax	142:54d1543e23e5	931
nixnax	142:54d1543e23e5	932	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	933	/// 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	934	void tcpHandler()
nixnax	142:54d1543e23e5	935	{
nixnax	142:54d1543e23e5	936	// IP header
nixnax	142:54d1543e23e5	937	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	938	char * ihl = ipPkt; // bottom 4 bits
nixnax	142:54d1543e23e5	939	char * pktLen = ipPkt+2; // 2 bytes
nixnax	142:54d1543e23e5	940	char * ident = ipPkt+4; // 2 bytes
nixnax	142:54d1543e23e5	941	char * protocol = ipPkt+9; // 1 byte
nixnax	149:969d98f6fb88	942	//char * headercheck= ipPkt+10; // 2 bytes
nixnax	142:54d1543e23e5	943	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	149:969d98f6fb88	944	//char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	945	int headerSizeIP = (ihl[0]&0xf)*4;
nixnax	142:54d1543e23e5	946	int packetLength = (pktLen[0]<<8)\|pktLen[1]; // ip total packet length
nixnax	142:54d1543e23e5	947
nixnax	142:54d1543e23e5	948	// TCP header
nixnax	142:54d1543e23e5	949	char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax	149:969d98f6fb88	950	//char * srctcp = tcp + 0; // 2 bytes
nixnax	149:969d98f6fb88	951	//char * dsttcp = tcp + 2; // 2 bytes
nixnax	142:54d1543e23e5	952	char * seqtcp = tcp + 4; // 4 bytes
nixnax	142:54d1543e23e5	953	char * acktcp = tcp + 8; // 4 bytes
nixnax	142:54d1543e23e5	954	char * offset = tcp + 12; // 4 bits
nixnax	142:54d1543e23e5	955	char * flagbitstcp = tcp + 12; // 9 bits
nixnax	142:54d1543e23e5	956	char * windowsizetcp = tcp + 14; // 2 bytes
nixnax	142:54d1543e23e5	957	char * checksumtcp = tcp + 16; // 2 bytes
nixnax	142:54d1543e23e5	958
nixnax	142:54d1543e23e5	959	if(ident) {}; // shut up unused variable reference warning
nixnax	142:54d1543e23e5	960	int tcpSize = packetLength - headerSizeIP;
nixnax	142:54d1543e23e5	961	int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax	142:54d1543e23e5	962	int protocolIP = protocol[0];
nixnax	142:54d1543e23e5	963	char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax	142:54d1543e23e5	964	int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax	142:54d1543e23e5	965	char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax	142:54d1543e23e5	966	unsigned int seq_in = (seqtcp[0]<<24)\|(seqtcp[1]<<16)\|(seqtcp[2]<<8)\|(seqtcp[3]);
nixnax	142:54d1543e23e5	967	unsigned int ack_in = (acktcp[0]<<24)\|(acktcp[1]<<16)\|(acktcp[2]<<8)\|(acktcp[3]);
nixnax	142:54d1543e23e5	968	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	969	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	970
nixnax	142:54d1543e23e5	971	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	142:54d1543e23e5	972	tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	142:54d1543e23e5	973	headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax	149:969d98f6fb88	974	ipPkt[0] = 0x45; // short IP packet size to 45
nixnax	142:54d1543e23e5	975	offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax	142:54d1543e23e5	976	packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	142:54d1543e23e5	977	pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	142:54d1543e23e5	978	pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	142:54d1543e23e5	979
nixnax	142:54d1543e23e5	980	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	981	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	142:54d1543e23e5	982	int flagsTCP = ((flagbitstcp[0]&1)<<8)\|flagbitstcp[1]; // the tcp flags we received
nixnax	142:54d1543e23e5	983	windowsizetcp[0] = (700 >> 8 ); // tcp window size hi byte
nixnax	142:54d1543e23e5	984	windowsizetcp[1] = (700 & 0xff); // tcp window size lo byte
nixnax	142:54d1543e23e5	985
nixnax	142:54d1543e23e5	986	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	987
nixnax	142:54d1543e23e5	988	switch ( flagsTCP ) {
nixnax	142:54d1543e23e5	989	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	990	return;
nixnax	142:54d1543e23e5	991	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	992	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	993	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	994	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	995	break;
nixnax	142:54d1543e23e5	996	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	142:54d1543e23e5	997	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	142:54d1543e23e5	998	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	999	dataLen = httpResponse(tcpDataOut); // send an http response
nixnax	142:54d1543e23e5	1000	} else {
nixnax	142:54d1543e23e5	1001	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not a web request, send a packet reporting number of received bytes
nixnax	142:54d1543e23e5	1002	}
nixnax	142:54d1543e23e5	1003	break;
nixnax	142:54d1543e23e5	1004	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1005	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1006	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1007	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1008	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1009	break;
nixnax	142:54d1543e23e5	1010	default:
nixnax	142:54d1543e23e5	1011	return; // ignore remaining packets
nixnax	142:54d1543e23e5	1012	} // switch
nixnax	142:54d1543e23e5	1013
nixnax	142:54d1543e23e5	1014	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1015	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1016	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1017	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1018
nixnax	142:54d1543e23e5	1019	acktcp[0]=ack_out>>24;
nixnax	142:54d1543e23e5	1020	acktcp[1]=ack_out>>16;
nixnax	142:54d1543e23e5	1021	acktcp[2]=ack_out>>8;
nixnax	142:54d1543e23e5	1022	acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax	142:54d1543e23e5	1023	seqtcp[0]=seq_out>>24;
nixnax	142:54d1543e23e5	1024	seqtcp[1]=seq_out>>16;
nixnax	142:54d1543e23e5	1025	seqtcp[2]=seq_out>>8;
nixnax	142:54d1543e23e5	1026	seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax	142:54d1543e23e5	1027
nixnax	142:54d1543e23e5	1028	flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1029
nixnax	142:54d1543e23e5	1030	// increment our outgoing ip packet counter
nixnax	142:54d1543e23e5	1031	ppp.ip.ident++; // get next ident number for our packet
nixnax	142:54d1543e23e5	1032
nixnax	142:54d1543e23e5	1033	// Now we recalculate all the header sizes
nixnax	142:54d1543e23e5	1034	tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax	142:54d1543e23e5	1035	int newPacketSize = headerSizeIP + tcpSize; // calculate size of the outgoing packet
nixnax	142:54d1543e23e5	1036	pktLen[0] = (newPacketSize>>8);
nixnax	142:54d1543e23e5	1037	pktLen[1]=newPacketSize; // ip total packet size
nixnax	142:54d1543e23e5	1038	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	1039
nixnax	142:54d1543e23e5	1040	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1041	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	142:54d1543e23e5	1042
nixnax	142:54d1543e23e5	1043	// now we have to build the so-called 12-byte TCP "pseudo-header" in front of the TCP header (containing some IP header values) in order to correctly calculate the TCP checksum
nixnax	142:54d1543e23e5	1044	// this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax	149:969d98f6fb88	1045	char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax	142:54d1543e23e5	1046	char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax	142:54d1543e23e5	1047	memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax	142:54d1543e23e5	1048	memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax	142:54d1543e23e5	1049	memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax	142:54d1543e23e5	1050	memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax	142:54d1543e23e5	1051	memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax	142:54d1543e23e5	1052	memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax	142:54d1543e23e5	1053	// pseudo-header built, now we can calculate TCP checksum
nixnax	142:54d1543e23e5	1054	checksumtcp[0]=0;
nixnax	142:54d1543e23e5	1055	checksumtcp[1]=0;
nixnax	142:54d1543e23e5	1056	unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax	142:54d1543e23e5	1057	checksumtcp[0]=pseudoHeaderSum>>8;
nixnax	142:54d1543e23e5	1058	checksumtcp[1]=pseudoHeaderSum;
nixnax	142:54d1543e23e5	1059	memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax	147:0f40005cbc5f	1060	// IP and TCP checksums done
nixnax	142:54d1543e23e5	1061	dumpHeaderIP(1); // dump outgoing IP header
nixnax	142:54d1543e23e5	1062	dumpHeaderTCP(1); // dump outgoing TCP header
nixnax	142:54d1543e23e5	1063	for (int i=0; i<45*1000/10; i++) { // 45 ms delay before sending frame - a typical internet delay time
nixnax	142:54d1543e23e5	1064	checkPc(); // catch any incoming characters
nixnax	142:54d1543e23e5	1065	wait_us(10); // wait less than 1 character duration at 115200
nixnax	142:54d1543e23e5	1066	}
nixnax	144:01d98cf7738e	1067	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1068	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1069	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1070	}
nixnax	142:54d1543e23e5	1071
nixnax	142:54d1543e23e5	1072
nixnax	142:54d1543e23e5	1073	/// dump the TCP data to the debug serial port
nixnax	142:54d1543e23e5	1074	void dumpDataTCP()
nixnax	142:54d1543e23e5	1075	{
nixnax	142:54d1543e23e5	1076	int ipPktLen = (ppp.pkt.buf[6]<<8)\|ppp.pkt.buf[7]; // overall length of ip packet
nixnax	142:54d1543e23e5	1077	int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax	142:54d1543e23e5	1078	int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax	142:54d1543e23e5	1079	int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax	142:54d1543e23e5	1080	if (v1) {
nixnax	142:54d1543e23e5	1081	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	1082	checkPc();
nixnax	142:54d1543e23e5	1083	sprintf(pbuf, "TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax	142:54d1543e23e5	1084	checkPc();
nixnax	142:54d1543e23e5	1085	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	1086	}
nixnax	142:54d1543e23e5	1087	if (dataLen > 0) {
nixnax	142:54d1543e23e5	1088	ppp.pkt.buf[4+ipHeaderLen+headerSizeTCP+dataLen]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	142:54d1543e23e5	1089	putsWhileCheckingInput( ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP ); // print the tcp payload data
nixnax	142:54d1543e23e5	1090	putsWhileCheckingInput("\n");
nixnax	142:54d1543e23e5	1091	}
nixnax	142:54d1543e23e5	1092	}
nixnax	142:54d1543e23e5	1093
nixnax	142:54d1543e23e5	1094	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1095	void TCPpacket()
nixnax	142:54d1543e23e5	1096	{
nixnax	142:54d1543e23e5	1097	dumpHeaderIP(0); // dump incoming packet header
nixnax	142:54d1543e23e5	1098	dumpHeaderTCP(0); // dump incoming packet header
nixnax	142:54d1543e23e5	1099	if (v2) dumpDataTCP();
nixnax	142:54d1543e23e5	1100	tcpHandler();
nixnax	142:54d1543e23e5	1101	}
nixnax	142:54d1543e23e5	1102
nixnax	142:54d1543e23e5	1103	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1104	void otherProtocol()
nixnax	142:54d1543e23e5	1105	{
nixnax	142:54d1543e23e5	1106	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1107	}
nixnax	142:54d1543e23e5	1108
nixnax	142:54d1543e23e5	1109	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1110	void IPframe()
nixnax	142:54d1543e23e5	1111	{
nixnax	142:54d1543e23e5	1112	int protocol = ppp.pkt.buf[13];
nixnax	142:54d1543e23e5	1113	switch (protocol) {
nixnax	142:54d1543e23e5	1114	case 1:
nixnax	142:54d1543e23e5	1115	ICMPpacket();
nixnax	142:54d1543e23e5	1116	break;
nixnax	142:54d1543e23e5	1117	case 2:
nixnax	142:54d1543e23e5	1118	IGMPpacket();
nixnax	142:54d1543e23e5	1119	break;
nixnax	142:54d1543e23e5	1120	case 17:
nixnax	142:54d1543e23e5	1121	UDPpacket();
nixnax	142:54d1543e23e5	1122	break;
nixnax	142:54d1543e23e5	1123	case 6:
nixnax	142:54d1543e23e5	1124	TCPpacket();
nixnax	142:54d1543e23e5	1125	break;
nixnax	142:54d1543e23e5	1126	default:
nixnax	142:54d1543e23e5	1127	otherProtocol();
nixnax	142:54d1543e23e5	1128	}
nixnax	142:54d1543e23e5	1129	}
nixnax	142:54d1543e23e5	1130
nixnax	142:54d1543e23e5	1131	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1132	void LCPconfReq()
nixnax	142:54d1543e23e5	1133	{
nixnax	142:54d1543e23e5	1134	debugPrintf("LCP Config ");
nixnax	142:54d1543e23e5	1135	if (ppp.pkt.buf[7] != 4) {
nixnax	142:54d1543e23e5	1136	ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1137	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1138	sendPppFrame();
nixnax	142:54d1543e23e5	1139	} else {
nixnax	142:54d1543e23e5	1140	ppp.pkt.buf[4]=2; // ack zero conf
nixnax	142:54d1543e23e5	1141	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1142	sendPppFrame();
nixnax	142:54d1543e23e5	1143	debugPrintf("LCP Ask\n");
nixnax	142:54d1543e23e5	1144	ppp.pkt.buf[4]=1; // request no options
nixnax	144:01d98cf7738e	1145	sendPppFrame();
nixnax	142:54d1543e23e5	1146	}
nixnax	142:54d1543e23e5	1147	}
nixnax	142:54d1543e23e5	1148
nixnax	142:54d1543e23e5	1149	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1150	void LCPconfAck()
nixnax	142:54d1543e23e5	1151	{
nixnax	142:54d1543e23e5	1152	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1153	}
nixnax	142:54d1543e23e5	1154
nixnax	143:c5019f856a56	1155	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1156	void LCPend()
nixnax	142:54d1543e23e5	1157	{
nixnax	142:54d1543e23e5	1158	ppp.pkt.buf[4]=6;
nixnax	144:01d98cf7738e	1159	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1160	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1161	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1162	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1163	}
nixnax	142:54d1543e23e5	1164
nixnax	142:54d1543e23e5	1165	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1166	void LCPother()
nixnax	142:54d1543e23e5	1167	{
nixnax	142:54d1543e23e5	1168	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1169	dumpPPPFrame();
nixnax	142:54d1543e23e5	1170	}
nixnax	142:54d1543e23e5	1171
nixnax	142:54d1543e23e5	1172	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1173	void LCPframe()
nixnax	142:54d1543e23e5	1174	{
nixnax	142:54d1543e23e5	1175	int code = ppp.pkt.buf[4];
nixnax	142:54d1543e23e5	1176	switch (code) {
nixnax	142:54d1543e23e5	1177	case 1:
nixnax	142:54d1543e23e5	1178	LCPconfReq();
nixnax	142:54d1543e23e5	1179	break; // config request
nixnax	142:54d1543e23e5	1180	case 2:
nixnax	142:54d1543e23e5	1181	LCPconfAck();
nixnax	142:54d1543e23e5	1182	break; // config ack
nixnax	142:54d1543e23e5	1183	case 5:
nixnax	142:54d1543e23e5	1184	LCPend();
nixnax	142:54d1543e23e5	1185	break; // end connection
nixnax	142:54d1543e23e5	1186	default:
nixnax	142:54d1543e23e5	1187	LCPother();
nixnax	142:54d1543e23e5	1188	}
nixnax	142:54d1543e23e5	1189	}
nixnax	142:54d1543e23e5	1190
nixnax	142:54d1543e23e5	1191	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1192	void discardedFrame()
nixnax	142:54d1543e23e5	1193	{
nixnax	142:54d1543e23e5	1194	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	1195	}
nixnax	142:54d1543e23e5	1196
nixnax	142:54d1543e23e5	1197	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1198	void determinePacketType()
nixnax	142:54d1543e23e5	1199	{
nixnax	142:54d1543e23e5	1200	if ( ppp.pkt.buf[0] != 0xff ) {
nixnax	142:54d1543e23e5	1201	debugPrintf("byte0 != ff\n");
nixnax	142:54d1543e23e5	1202	return;
nixnax	142:54d1543e23e5	1203	}
nixnax	142:54d1543e23e5	1204	if ( ppp.pkt.buf[1] != 3 ) {
nixnax	142:54d1543e23e5	1205	debugPrintf("byte1 != 3\n");
nixnax	142:54d1543e23e5	1206	return;
nixnax	142:54d1543e23e5	1207	}
nixnax	142:54d1543e23e5	1208	if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax	142:54d1543e23e5	1209	debugPrintf("byte2 != 21\n");
nixnax	142:54d1543e23e5	1210	return;
nixnax	142:54d1543e23e5	1211	}
nixnax	142:54d1543e23e5	1212	int packetType = ppp.pkt.buf[2];
nixnax	142:54d1543e23e5	1213	switch (packetType) {
nixnax	142:54d1543e23e5	1214	case 0xc0:
nixnax	142:54d1543e23e5	1215	LCPframe();
nixnax	142:54d1543e23e5	1216	break; // link control
nixnax	142:54d1543e23e5	1217	case 0x80:
nixnax	142:54d1543e23e5	1218	IPCPframe();
nixnax	142:54d1543e23e5	1219	break; // IP control
nixnax	142:54d1543e23e5	1220	case 0x00:
nixnax	142:54d1543e23e5	1221	IPframe();
nixnax	142:54d1543e23e5	1222	break; // IP itself
nixnax	142:54d1543e23e5	1223	default:
nixnax	142:54d1543e23e5	1224	discardedFrame();
nixnax	142:54d1543e23e5	1225	}
nixnax	142:54d1543e23e5	1226	}
nixnax	142:54d1543e23e5	1227
nixnax	146:a45f49a2b29c	1228	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1229	void sniff()
nixnax	146:a45f49a2b29c	1230	{
nixnax	146:a45f49a2b29c	1231	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	1232	}
nixnax	146:a45f49a2b29c	1233
nixnax	142:54d1543e23e5	1234	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1235	void waitForPppFrame()
nixnax	142:54d1543e23e5	1236	{
nixnax	142:54d1543e23e5	1237	while(1) {
nixnax	142:54d1543e23e5	1238	checkPc(); // handle received characters
nixnax	142:54d1543e23e5	1239	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1240	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1241	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1242	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1243	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1244	ppp.firstFrame=0;
nixnax	142:54d1543e23e5	1245	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1246	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	142:54d1543e23e5	1247	} else {
nixnax	142:54d1543e23e5	1248	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1249	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1250	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1251	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1252	break;
nixnax	142:54d1543e23e5	1253	}
nixnax	142:54d1543e23e5	1254	}
nixnax	142:54d1543e23e5	1255	}
nixnax	142:54d1543e23e5	1256	}
nixnax	142:54d1543e23e5	1257	}
nixnax	142:54d1543e23e5	1258
nixnax	142:54d1543e23e5	1259	/// scan for a connect string ("CLIENT") from the host PC, if found, we set ppp.oline to true, which will the IP packet scanner
nixnax	142:54d1543e23e5	1260	void scanForConnectString()
nixnax	142:54d1543e23e5	1261	{
nixnax	142:54d1543e23e5	1262	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1263	checkPc(); // gather received characters
nixnax	142:54d1543e23e5	1264	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1265	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1266	if (found1 != NULL) {
nixnax	142:54d1543e23e5	1267	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	143:c5019f856a56	1268	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	142:54d1543e23e5	1269	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1270	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1271	checkPc();
nixnax	142:54d1543e23e5	1272	}
nixnax	142:54d1543e23e5	1273	}
nixnax	142:54d1543e23e5	1274	}
nixnax	142:54d1543e23e5	1275
nixnax	144:01d98cf7738e	1276	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1277	void initializePpp()
nixnax	142:54d1543e23e5	1278	{
nixnax	142:54d1543e23e5	1279	pc.baud(115200); // USB serial port to pc
nixnax	144:01d98cf7738e	1280	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	142:54d1543e23e5	1281	debugPrintf("\x1b[2J\x1b[H\x1b[30mmbed PPP-Blinky HTTP & WebSocket server ready :)\n"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax	142:54d1543e23e5	1282	pppInitStruct(); // initialize all the PPP properties
nixnax	143:c5019f856a56	1283	}

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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.