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@144:01d98cf7738e, 2017-08-29 (annotated)

Committer:: nixnax
Date:: Tue Aug 29 18:42:20 2017 +0000
Revision:: 144:01d98cf7738e
Parent:: 143:c5019f856a56
Child:: 145:098b6ed2f7f2

If UDP message starts with "echo" send it back.

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	142:54d1543e23e5	35	// 172.10.10.2/xb also returns a number, but issues a fast refresh 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	142:54d1543e23e5	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 this.
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	142:54d1543e23e5	47	#define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax	142:54d1543e23e5	48
nixnax	142:54d1543e23e5	49	// here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax	142:54d1543e23e5	50	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	51	#if defined(TARGET_LPC1768)
nixnax	142:54d1543e23e5	52	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	53	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	142:54d1543e23e5	54	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	55	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	56	#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	57	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	142:54d1543e23e5	58	Serial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	142:54d1543e23e5	59	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	60	// 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	61	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	62	#else
nixnax	142:54d1543e23e5	63	#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	64	#endif
nixnax	142:54d1543e23e5	65	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we print debug messages */
nixnax	142:54d1543e23e5	66	#define debugPutc(x...) xx.putc(x)
nixnax	142:54d1543e23e5	67	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	68	#else
nixnax	142:54d1543e23e5	69	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	70	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	71	#define debugPutc(x...) {}
nixnax	142:54d1543e23e5	72	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	73	#endif
nixnax	142:54d1543e23e5	74
nixnax	142:54d1543e23e5	75	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	142:54d1543e23e5	76	#define v0 1
nixnax	142:54d1543e23e5	77	#define v1 0
nixnax	142:54d1543e23e5	78	#define v2 0
nixnax	142:54d1543e23e5	79	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	142:54d1543e23e5	80	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	81
nixnax	142:54d1543e23e5	82	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	83	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	84
nixnax	142:54d1543e23e5	85	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	86	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	87	<html>\
nixnax	142:54d1543e23e5	88	<head>\
nixnax	142:54d1543e23e5	89	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	90	<script>\
nixnax	142:54d1543e23e5	91	window.onload=function(){\
nixnax	142:54d1543e23e5	92	setInterval(function(){function x(){return document.getElementById('w');};\
nixnax	142:54d1543e23e5	93	x().textContent=parseInt(x().textContent)+1;},100);};\
nixnax	142:54d1543e23e5	94	</script>\
nixnax	142:54d1543e23e5	95	</head>\
nixnax	142:54d1543e23e5	96	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	97	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	98	<h1 id=\"w\">0</h1>\
nixnax	142:54d1543e23e5	99	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	142:54d1543e23e5	100	<h1><a href=\"/ws\">WebSocket Demo</a></h1>\
nixnax	142:54d1543e23e5	101	<h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax	142:54d1543e23e5	102	<h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax	142:54d1543e23e5	103	<h1><a href=\"http://jsfiddle.net/d26cyuh2/\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	104	</body>\
nixnax	142:54d1543e23e5	105	</html>"; // size = 634 bytes plus 1 null byte = 635 bytes
nixnax	142:54d1543e23e5	106
nixnax	142:54d1543e23e5	107	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	108	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	109	<html>\
nixnax	142:54d1543e23e5	110	<head>\
nixnax	142:54d1543e23e5	111	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	112	<script>\
nixnax	142:54d1543e23e5	113	window.onload=function(){\
nixnax	142:54d1543e23e5	114	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	115	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	116	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	117	var ctr=0;\
nixnax	142:54d1543e23e5	118	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	119	btn.onclick=function(){\
nixnax	142:54d1543e23e5	120	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	121	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	122	x.onopen=function(){\
nixnax	142:54d1543e23e5	123	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	124	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	125	};\
nixnax	142:54d1543e23e5	126	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	127	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	128	} else {\
nixnax	142:54d1543e23e5	129	x.send(ctr);\
nixnax	142:54d1543e23e5	130	ctr=ctr+1;\
nixnax	142:54d1543e23e5	131	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	132	}\
nixnax	142:54d1543e23e5	133	};\
nixnax	142:54d1543e23e5	134	};\
nixnax	142:54d1543e23e5	135	</script>\
nixnax	142:54d1543e23e5	136	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	137	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	138	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	139	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	140	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	141	</body>\
nixnax	142:54d1543e23e5	142	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	143
nixnax	142:54d1543e23e5	144	// 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	145	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	146	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	147	// See instructions at the top.
nixnax	142:54d1543e23e5	148	// 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	149	BufferedSerial pc(USBTX, USBRX, 100); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	150
nixnax	142:54d1543e23e5	151	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	152
nixnax	142:54d1543e23e5	153	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	154	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	155
nixnax	142:54d1543e23e5	156	/// a structure to keep all our ppp globals in
nixnax	142:54d1543e23e5	157	struct pppType {
nixnax	142:54d1543e23e5	158	int online; // we hunt for a PPP connection if this is zero
nixnax	143:c5019f856a56	159	int hostIP; // ip address of host
nixnax	142:54d1543e23e5	160	int crc; // for calculating IP and TCP CRCs
nixnax	142:54d1543e23e5	161	int ledState; // state of LED1
nixnax	142:54d1543e23e5	162	int httpPageCount;
nixnax	142:54d1543e23e5	163	int firstFrame; // cleared after first frame
nixnax	142:54d1543e23e5	164	struct {
nixnax	142:54d1543e23e5	165	#define RXBUFLEN (1<<11)
nixnax	142:54d1543e23e5	166	// the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 2048 bytes)
nixnax	142:54d1543e23e5	167	char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax	142:54d1543e23e5	168	int head;
nixnax	142:54d1543e23e5	169	int tail;
nixnax	142:54d1543e23e5	170	int rtail;
nixnax	142:54d1543e23e5	171	int buflevel;
nixnax	142:54d1543e23e5	172	} rx; // serial port objects
nixnax	142:54d1543e23e5	173	struct {
nixnax	142:54d1543e23e5	174	int len; // number of bytes in buffer
nixnax	142:54d1543e23e5	175	int crc; // PPP CRC (frame check)
nixnax	142:54d1543e23e5	176	#define PPP_max_size 2500
nixnax	142:54d1543e23e5	177	// we are assuming 1000 bytes more than MTU size of 1500 - due to the PPP encoding of special bytes
nixnax	142:54d1543e23e5	178	char buf[PPP_max_size]; // send and receive buffer large enough for raw, encoded PPP/HDLC frames
nixnax	142:54d1543e23e5	179	} pkt; // ppp buffer objects
nixnax	142:54d1543e23e5	180	struct {
nixnax	142:54d1543e23e5	181	int frameStartIndex; // frame start marker
nixnax	142:54d1543e23e5	182	int frameEndIndex; // frame end marker
nixnax	142:54d1543e23e5	183	} hdlc; // hdlc frame objects
nixnax	142:54d1543e23e5	184	struct {
nixnax	142:54d1543e23e5	185	unsigned int ident; // our IP ident value (outgoing frame count)
nixnax	142:54d1543e23e5	186	} ip; // ip related object
nixnax	142:54d1543e23e5	187	};
nixnax	142:54d1543e23e5	188
nixnax	142:54d1543e23e5	189	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	190
nixnax	142:54d1543e23e5	191	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	192	void pppInitStruct()
nixnax	142:54d1543e23e5	193	{
nixnax	142:54d1543e23e5	194	memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax	142:54d1543e23e5	195	ppp.online=0;
nixnax	142:54d1543e23e5	196	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	197	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	198	ppp.rx.head=0;
nixnax	142:54d1543e23e5	199	ppp.rx.buflevel=0;
nixnax	142:54d1543e23e5	200	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	201	ppp.ip.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	202	ppp.ledState=0;
nixnax	142:54d1543e23e5	203	ppp.hdlc.frameStartIndex=0;
nixnax	142:54d1543e23e5	204	ppp.httpPageCount=0;
nixnax	142:54d1543e23e5	205	ppp.firstFrame=1;
nixnax	142:54d1543e23e5	206	}
nixnax	142:54d1543e23e5	207
nixnax	142:54d1543e23e5	208	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	209	void led1Toggle()
nixnax	142:54d1543e23e5	210	{
nixnax	142:54d1543e23e5	211	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	212	ppp.ledState++;
nixnax	142:54d1543e23e5	213
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	142:54d1543e23e5	267	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	142:54d1543e23e5	268	void qq()
nixnax	142:54d1543e23e5	269	{
nixnax	142:54d1543e23e5	270	if ( pc.readable() ) putsWhileCheckingInput( "Character available!\n" );
nixnax	142:54d1543e23e5	271	}
nixnax	142:54d1543e23e5	272
nixnax	142:54d1543e23e5	273	/// Initialize the PPP CRC total
nixnax	142:54d1543e23e5	274	void crcReset()
nixnax	142:54d1543e23e5	275	{
nixnax	142:54d1543e23e5	276	ppp.crc=0xffff; // crc restart
nixnax	142:54d1543e23e5	277	}
nixnax	142:54d1543e23e5	278
nixnax	142:54d1543e23e5	279	/// update the cumulative PPP CRC
nixnax	142:54d1543e23e5	280	void crcDo(int x)
nixnax	142:54d1543e23e5	281	{
nixnax	142:54d1543e23e5	282	for (int i=0; i<8; i++) {
nixnax	142:54d1543e23e5	283	ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax	142:54d1543e23e5	284	x>>=1;
nixnax	142:54d1543e23e5	285	}
nixnax	142:54d1543e23e5	286	checkPc(); // handle input
nixnax	142:54d1543e23e5	287	}
nixnax	142:54d1543e23e5	288
nixnax	142:54d1543e23e5	289	/// calculate the PPP CRC on an entire block of memory
nixnax	142:54d1543e23e5	290	int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	291	{
nixnax	142:54d1543e23e5	292	crcReset();
nixnax	142:54d1543e23e5	293	for(int i=0; i<size; i++)crcDo(*buf++);
nixnax	142:54d1543e23e5	294	return ppp.crc;
nixnax	142:54d1543e23e5	295	}
nixnax	142:54d1543e23e5	296
nixnax	142:54d1543e23e5	297	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	298	int pc_getBuf()
nixnax	142:54d1543e23e5	299	{
nixnax	142:54d1543e23e5	300	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	142:54d1543e23e5	301	ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax	142:54d1543e23e5	302	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	303	return x;
nixnax	142:54d1543e23e5	304	}
nixnax	142:54d1543e23e5	305
nixnax	142:54d1543e23e5	306	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	307	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	308	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	142:54d1543e23e5	309	/// In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	310	void dumpPPPFrame()
nixnax	142:54d1543e23e5	311	{
nixnax	142:54d1543e23e5	312	char pbuf[30];
nixnax	142:54d1543e23e5	313	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	314	checkPc();
nixnax	142:54d1543e23e5	315	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	142:54d1543e23e5	316	checkPc();
nixnax	142:54d1543e23e5	317	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	318	}
nixnax	142:54d1543e23e5	319	checkPc();
nixnax	142:54d1543e23e5	320	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	142:54d1543e23e5	321	checkPc();
nixnax	142:54d1543e23e5	322	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	323	}
nixnax	142:54d1543e23e5	324
nixnax	142:54d1543e23e5	325	/// Process a received PPP frame
nixnax	142:54d1543e23e5	326	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	327	{
nixnax	142:54d1543e23e5	328	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	329	if(start==end) {
nixnax	142:54d1543e23e5	330	return; // empty frame
nixnax	142:54d1543e23e5	331	}
nixnax	142:54d1543e23e5	332	crcReset();
nixnax	142:54d1543e23e5	333	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	334	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	335	int unstuff=0;
nixnax	142:54d1543e23e5	336	int idx = start;
nixnax	142:54d1543e23e5	337	while(1) {
nixnax	142:54d1543e23e5	338	checkPc();
nixnax	142:54d1543e23e5	339	if (unstuff==0) {
nixnax	142:54d1543e23e5	340	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	341	else {
nixnax	142:54d1543e23e5	342	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	343	ppp.pkt.len++;
nixnax	142:54d1543e23e5	344	dest++;
nixnax	142:54d1543e23e5	345	crcDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	346	}
nixnax	142:54d1543e23e5	347	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	348	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	349	ppp.pkt.len++;
nixnax	142:54d1543e23e5	350	dest++;
nixnax	142:54d1543e23e5	351	crcDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	352	unstuff=0;
nixnax	142:54d1543e23e5	353	}
nixnax	142:54d1543e23e5	354	idx = (idx+1) & (RXBUFLEN-1);
nixnax	142:54d1543e23e5	355	if (idx == end) break;
nixnax	142:54d1543e23e5	356	}
nixnax	142:54d1543e23e5	357	ppp.pkt.crc = ppp.crc & 0xffff;
nixnax	142:54d1543e23e5	358	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	359	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	360	determinePacketType();
nixnax	142:54d1543e23e5	361	} else {
nixnax	142:54d1543e23e5	362	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	363	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	364	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	365	checkPc();
nixnax	142:54d1543e23e5	366	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	142:54d1543e23e5	367	checkPc();
nixnax	142:54d1543e23e5	368	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	369	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	370	#endif
nixnax	142:54d1543e23e5	371	}
nixnax	142:54d1543e23e5	372	}
nixnax	142:54d1543e23e5	373
nixnax	142:54d1543e23e5	374	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	375	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	376	{
nixnax	142:54d1543e23e5	377	checkPc(); // check input
nixnax	142:54d1543e23e5	378	pc.putc(ch);
nixnax	142:54d1543e23e5	379	checkPc();
nixnax	142:54d1543e23e5	380	}
nixnax	142:54d1543e23e5	381
nixnax	142:54d1543e23e5	382	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	383	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	384	{
nixnax	142:54d1543e23e5	385	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	386	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	387	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	388	} else {
nixnax	142:54d1543e23e5	389	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	390	}
nixnax	142:54d1543e23e5	391	}
nixnax	142:54d1543e23e5	392
nixnax	142:54d1543e23e5	393	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	394	void sendPppFrame()
nixnax	143:c5019f856a56	395	{
nixnax	142:54d1543e23e5	396	int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	397	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	398	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	399	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	400	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	401	wait_us(86); // wait one character time
nixnax	142:54d1543e23e5	402	checkPc();
nixnax	142:54d1543e23e5	403	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	404	}
nixnax	142:54d1543e23e5	405	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	406	}
nixnax	142:54d1543e23e5	407
nixnax	143:c5019f856a56	408	/// 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	409	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	410	{
nixnax	143:c5019f856a56	411	int result=0;
nixnax	143:c5019f856a56	412	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	413	return result;
nixnax	143:c5019f856a56	414	}
nixnax	143:c5019f856a56	415
nixnax	142:54d1543e23e5	416	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	417	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	418	{
nixnax	142:54d1543e23e5	419	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	143:c5019f856a56	420	if(ppp.pkt.buf[8]==3) {
nixnax	143:c5019f856a56	421	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	143:c5019f856a56	422	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	423	}
nixnax	143:c5019f856a56	424
nixnax	142:54d1543e23e5	425	ppp.pkt.buf[4]=2; // change code to ack
nixnax	144:01d98cf7738e	426	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	427
nixnax	142:54d1543e23e5	428	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	142:54d1543e23e5	429	ppp.pkt.buf[4]=1; // change code to request
nixnax	142:54d1543e23e5	430	ppp.pkt.buf[7]=4; // no options in this request
nixnax	142:54d1543e23e5	431	ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	432	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	433	}
nixnax	142:54d1543e23e5	434
nixnax	142:54d1543e23e5	435	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	436	void ipcpAckHandler()
nixnax	142:54d1543e23e5	437	{
nixnax	142:54d1543e23e5	438	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	439	}
nixnax	142:54d1543e23e5	440
nixnax	143:c5019f856a56	441	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	442	/// 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	443	void ipcpNackHandler()
nixnax	142:54d1543e23e5	444	{
nixnax	143:c5019f856a56	445	debugPrintf("Their IPCP Nack");
nixnax	142:54d1543e23e5	446	if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax	142:54d1543e23e5	447	ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	448	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	449	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	142:54d1543e23e5	450	} // if it's not an IP nack we ignore it
nixnax	142:54d1543e23e5	451	}
nixnax	142:54d1543e23e5	452
nixnax	142:54d1543e23e5	453	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	454	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	455	{
nixnax	142:54d1543e23e5	456	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	457	}
nixnax	142:54d1543e23e5	458
nixnax	142:54d1543e23e5	459	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	460	void IPCPframe()
nixnax	142:54d1543e23e5	461	{
nixnax	142:54d1543e23e5	462	int code = ppp.pkt.buf[4]; // packet type is here
nixnax	142:54d1543e23e5	463	switch (code) {
nixnax	142:54d1543e23e5	464	case 1:
nixnax	142:54d1543e23e5	465	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	466	break;
nixnax	142:54d1543e23e5	467	case 2:
nixnax	142:54d1543e23e5	468	ipcpAckHandler();
nixnax	142:54d1543e23e5	469	break;
nixnax	142:54d1543e23e5	470	case 3:
nixnax	142:54d1543e23e5	471	ipcpNackHandler();
nixnax	142:54d1543e23e5	472	break;
nixnax	142:54d1543e23e5	473	default:
nixnax	142:54d1543e23e5	474	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	475	}
nixnax	142:54d1543e23e5	476	}
nixnax	142:54d1543e23e5	477
nixnax	142:54d1543e23e5	478	/// process an incoming UDP packet
nixnax	142:54d1543e23e5	479	void UDPpacket()
nixnax	142:54d1543e23e5	480	{
nixnax	142:54d1543e23e5	481	char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax	142:54d1543e23e5	482	int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax	142:54d1543e23e5	483	char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax	143:c5019f856a56	484	char * udpInf = udpBlock+8; // actual start of info
nixnax	142:54d1543e23e5	485	char * udpSrc = udpBlock; // source port
nixnax	142:54d1543e23e5	486	char * udpDst = udpBlock+2; // destination port
nixnax	142:54d1543e23e5	487	char * udpLen = udpBlock+4; // udp data length
nixnax	144:01d98cf7738e	488	char * udpCks = udpBlock+6; // udp checksum
nixnax	143:c5019f856a56	489	char * srcIP = udpPkt+12; // udp src addr
nixnax	143:c5019f856a56	490	char * dstIP = udpPkt+16; // udp dst addr
nixnax	144:01d98cf7738e	491	if (udpLen); // shut up compiler warning for unused udpLen
nixnax	144:01d98cf7738e	492	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	493	int srcPort = (udpSrc[0]<<8) \| udpSrc[1];
nixnax	142:54d1543e23e5	494	int dstPort = (udpDst[0]<<8) \| udpDst[1];
nixnax	143:c5019f856a56	495	int udpLength = ((udpLen[0]<<8) \| udpLen[1]) - 8; // size of the actual udp data
nixnax	142:54d1543e23e5	496	if(v0) debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax	142:54d1543e23e5	497	if(v0) debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax	142:54d1543e23e5	498	if(v0) debugPrintf("Len %03d", udpLength);
nixnax	142:54d1543e23e5	499	if (v1) {
nixnax	143:c5019f856a56	500	int printSize = udpLength;
nixnax	143:c5019f856a56	501	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	142:54d1543e23e5	502	for (int i=0; i<printSize; i++) {
nixnax	142:54d1543e23e5	503	char ch = udpInf[i];
nixnax	142:54d1543e23e5	504	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	505	debugPrintf("%c", ch);
nixnax	142:54d1543e23e5	506	} else {
nixnax	142:54d1543e23e5	507	debugPrintf("_");
nixnax	142:54d1543e23e5	508	}
nixnax	142:54d1543e23e5	509	}
nixnax	142:54d1543e23e5	510	}
nixnax	142:54d1543e23e5	511	if (v0) debugPrintf("\n");
nixnax	143:c5019f856a56	512	#endif
nixnax	144:01d98cf7738e	513	if (strncmp(udpInf,"echo", 4)==0) { // if the UDP string starts with "echo" we echo it back
nixnax	144:01d98cf7738e	514	char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax	144:01d98cf7738e	515	memcpy(tempHold, srcIP,4);
nixnax	144:01d98cf7738e	516	memcpy(srcIP, dstIP,4);
nixnax	144:01d98cf7738e	517	memcpy(dstIP, tempHold,4); // swap ip address source/dest
nixnax	144:01d98cf7738e	518	memcpy(tempHold, udpSrc,2);
nixnax	144:01d98cf7738e	519	memcpy(udpSrc, udpDst,2);
nixnax	144:01d98cf7738e	520	memcpy(udpDst, tempHold,2); // swap udp port source/dest
nixnax	144:01d98cf7738e	521	memcpy(udpInf,"Got:",4);
nixnax	144:01d98cf7738e	522	memset(udpCks,0,2); // we don't compute the checksum (it's optional), so have to zero it
nixnax	144:01d98cf7738e	523	sendPppFrame();
nixnax	144:01d98cf7738e	524	}
nixnax	142:54d1543e23e5	525	}
nixnax	142:54d1543e23e5	526
nixnax	142:54d1543e23e5	527	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	142:54d1543e23e5	528	unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax	142:54d1543e23e5	529	{
nixnax	142:54d1543e23e5	530	unsigned int i,hi,lo,sum;
nixnax	142:54d1543e23e5	531	unsigned char placeHolder;
nixnax	142:54d1543e23e5	532	if (len&1) {
nixnax	142:54d1543e23e5	533	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	534	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	535	}
nixnax	142:54d1543e23e5	536	sum=0;
nixnax	142:54d1543e23e5	537	i=0;
nixnax	142:54d1543e23e5	538	while ( i<len ) {
nixnax	142:54d1543e23e5	539	checkPc();
nixnax	142:54d1543e23e5	540	hi = ptr[i++];
nixnax	142:54d1543e23e5	541	lo = ptr[i++];
nixnax	142:54d1543e23e5	542	sum = sum + ( (hi<<8) \| lo );
nixnax	142:54d1543e23e5	543	}
nixnax	142:54d1543e23e5	544	if (len&1) {
nixnax	142:54d1543e23e5	545	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	546	}
nixnax	142:54d1543e23e5	547	sum = (sum & 0xffff) + (sum>>16);
nixnax	142:54d1543e23e5	548	sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax	142:54d1543e23e5	549	return ~sum;
nixnax	142:54d1543e23e5	550	}
nixnax	142:54d1543e23e5	551
nixnax	142:54d1543e23e5	552	/// perform the checksum on an IP header
nixnax	142:54d1543e23e5	553	void headerCheckSum()
nixnax	142:54d1543e23e5	554	{
nixnax	142:54d1543e23e5	555	int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax	142:54d1543e23e5	556	char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax	142:54d1543e23e5	557	int sum=0;
nixnax	142:54d1543e23e5	558
nixnax	142:54d1543e23e5	559	for (int i=0; i<len/2; i++) {
nixnax	142:54d1543e23e5	560	int hi = *ptr;
nixnax	142:54d1543e23e5	561	ptr++;
nixnax	142:54d1543e23e5	562	int lo = *ptr;
nixnax	142:54d1543e23e5	563	ptr++;
nixnax	142:54d1543e23e5	564	int val = ( lo & 0xff ) \| ( (hi<<8) & 0xff00 );
nixnax	142:54d1543e23e5	565	sum = sum + val;
nixnax	142:54d1543e23e5	566	checkPc();
nixnax	142:54d1543e23e5	567	}
nixnax	142:54d1543e23e5	568	sum = sum + (sum>>16);
nixnax	142:54d1543e23e5	569	sum = ~sum;
nixnax	142:54d1543e23e5	570	ppp.pkt.buf[14]= (sum>>8);
nixnax	142:54d1543e23e5	571	ppp.pkt.buf[15]= (sum );
nixnax	142:54d1543e23e5	572	}
nixnax	142:54d1543e23e5	573
nixnax	142:54d1543e23e5	574	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	575	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	576	{
nixnax	142:54d1543e23e5	577	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	578	char * pktLen = ipPkt+2;
nixnax	142:54d1543e23e5	579	int packetLength = (pktLen[0]<<8) \| pktLen[1]; // icmp packet length
nixnax	142:54d1543e23e5	580	int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax	142:54d1543e23e5	581	char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax	142:54d1543e23e5	582	char * icmpSum = icmpType+2; // icmp checksum
nixnax	142:54d1543e23e5	583	#define ICMP_TYPE_PING_REQUEST 8
nixnax	142:54d1543e23e5	584	if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax	142:54d1543e23e5	585	char * ipTTL = ipPkt+8; // time to live
nixnax	142:54d1543e23e5	586	ipTTL[0]--; // decrement time to live
nixnax	142:54d1543e23e5	587	char * srcAdr = ipPkt+12;
nixnax	142:54d1543e23e5	588	char * dstAdr = ipPkt+16;
nixnax	142:54d1543e23e5	589	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	590	int icmpIdent = (icmpType[4]<<8)\|icmpType[5];
nixnax	142:54d1543e23e5	591	int icmpSequence = (icmpType[6]<<8)\|icmpType[7];
nixnax	142:54d1543e23e5	592	if(1) {
nixnax	142:54d1543e23e5	593	char pbuf[50];
nixnax	142:54d1543e23e5	594	checkPc();
nixnax	142:54d1543e23e5	595	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	596	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	597	checkPc();
nixnax	142:54d1543e23e5	598	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	142:54d1543e23e5	599	checkPc();
nixnax	142:54d1543e23e5	600	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	601	}
nixnax	142:54d1543e23e5	602	#endif
nixnax	142:54d1543e23e5	603	char src[4];
nixnax	142:54d1543e23e5	604	char dst[4];
nixnax	142:54d1543e23e5	605	memcpy(src, srcAdr,4);
nixnax	142:54d1543e23e5	606	memcpy(dst, dstAdr,4);
nixnax	142:54d1543e23e5	607	memcpy(srcAdr, dst,4);
nixnax	142:54d1543e23e5	608	memcpy(dstAdr, src,4); // swap src & dest ip
nixnax	142:54d1543e23e5	609	char * chkSum = ipPkt+10;
nixnax	142:54d1543e23e5	610	chkSum[0]=0;
nixnax	142:54d1543e23e5	611	chkSum[1]=0;
nixnax	142:54d1543e23e5	612	headerCheckSum(); // new ip header checksum
nixnax	142:54d1543e23e5	613	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	142:54d1543e23e5	614	icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	142:54d1543e23e5	615	icmpSum[0]=0;
nixnax	142:54d1543e23e5	616	icmpSum[1]=0; // zero the checksum for recalculation
nixnax	142:54d1543e23e5	617	int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax	142:54d1543e23e5	618	unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax	142:54d1543e23e5	619	icmpSum[0]=(sum>>8)&0xff;
nixnax	142:54d1543e23e5	620	icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax	142:54d1543e23e5	621
nixnax	142:54d1543e23e5	622	int printSize = icmpLength-8; // exclude size of icmp header
nixnax	142:54d1543e23e5	623	char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax	142:54d1543e23e5	624	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	625	if (0) {
nixnax	142:54d1543e23e5	626	for (int i=0; i<printSize; i++) {
nixnax	142:54d1543e23e5	627	char ch = icmpData[i];
nixnax	142:54d1543e23e5	628	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	629	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	630	} else {
nixnax	142:54d1543e23e5	631	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	632	}
nixnax	142:54d1543e23e5	633	}
nixnax	142:54d1543e23e5	634	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	635	}
nixnax	144:01d98cf7738e	636	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	637	} else {
nixnax	142:54d1543e23e5	638	if (v0) {
nixnax	142:54d1543e23e5	639	debugPrintf("ICMP type=%d \n", icmpType[0]);
nixnax	142:54d1543e23e5	640	}
nixnax	142:54d1543e23e5	641	}
nixnax	142:54d1543e23e5	642	}
nixnax	142:54d1543e23e5	643
nixnax	142:54d1543e23e5	644	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	645	void IGMPpacket()
nixnax	142:54d1543e23e5	646	{
nixnax	142:54d1543e23e5	647	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	648	}
nixnax	142:54d1543e23e5	649
nixnax	142:54d1543e23e5	650	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	651	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	652	{
nixnax	142:54d1543e23e5	653	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	654	checkPc(); // we are expecting the first character of the next packet
nixnax	142:54d1543e23e5	655	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	656	char * ident = ipPkt+4; // 2 bytes
nixnax	142:54d1543e23e5	657	#ifdef UNUSED_IP_VARIABLES
nixnax	142:54d1543e23e5	658	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	142:54d1543e23e5	659	char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	660	char * version = ipPkt; // top 4 bits
nixnax	142:54d1543e23e5	661	char * ihl = ipPkt; // bottom 4 bits
nixnax	142:54d1543e23e5	662	char * dscp = ipPkt+1; // top 6 bits
nixnax	142:54d1543e23e5	663	char * ecn = ipPkt+1; // lower 2 bits
nixnax	142:54d1543e23e5	664	char * pktLen = ipPkt+2; // 2 bytes
nixnax	142:54d1543e23e5	665	char * flags = ipPkt+6; // 2 bits
nixnax	142:54d1543e23e5	666	char * ttl = ipPkt+8; // 1 byte
nixnax	142:54d1543e23e5	667	char * protocol = ipPkt+9; // 1 byte
nixnax	142:54d1543e23e5	668	char * headercheck= ipPkt+10; // 2 bytes
nixnax	142:54d1543e23e5	669	int versionIP = (version[0]>>4)&0xf;
nixnax	142:54d1543e23e5	670	int headerSizeIP = (ihl[0]&0xf)*4;
nixnax	142:54d1543e23e5	671	int dscpIP = (dscp[0]>>2)&0x3f;
nixnax	142:54d1543e23e5	672	int ecnIP = ecn[0]&3;
nixnax	142:54d1543e23e5	673	int packetLength = (pktLen[0]<<8)\|pktLen[1]; // ip total packet length
nixnax	142:54d1543e23e5	674	int flagsIP = flags[0]>>14&3;
nixnax	142:54d1543e23e5	675	int ttlIP = ttl[0];
nixnax	142:54d1543e23e5	676	int protocolIP = protocol[0];
nixnax	142:54d1543e23e5	677	unsigned int checksumIP = (headercheck[0]<<8)\|headercheck[1];
nixnax	142:54d1543e23e5	678	#endif
nixnax	142:54d1543e23e5	679	int IPv4Id = (ident[0]<<8)\|ident[1];
nixnax	142:54d1543e23e5	680	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	681	int n=0;
nixnax	142:54d1543e23e5	682	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	683	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	684	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	685	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	686	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	142:54d1543e23e5	687	char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	688	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	689	#endif
nixnax	142:54d1543e23e5	690	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	691	#ifndef TCP_HEADER_DUMP_YES
nixnax	142:54d1543e23e5	692	putsWhileCheckingInput('\x1b[30m\n'); // there is no TCP header dump, so terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	693	#endif
nixnax	142:54d1543e23e5	694	#endif
nixnax	142:54d1543e23e5	695	}
nixnax	142:54d1543e23e5	696
nixnax	142:54d1543e23e5	697	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	698	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	699	{
nixnax	142:54d1543e23e5	700	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	142:54d1543e23e5	701	int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax	142:54d1543e23e5	702	char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax	142:54d1543e23e5	703	char * seqtcp = tcpStart + 4; // 4 bytes
nixnax	142:54d1543e23e5	704	char * acktcp = tcpStart + 8; // 4 bytes
nixnax	142:54d1543e23e5	705	char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax	142:54d1543e23e5	706	unsigned int seq = (seqtcp[0]<<24)\|(seqtcp[1]<<16)\|(seqtcp[2]<<8)\|(seqtcp[3]);
nixnax	142:54d1543e23e5	707	unsigned int ack = (acktcp[0]<<24)\|(acktcp[1]<<16)\|(acktcp[2]<<8)\|(acktcp[3]);
nixnax	142:54d1543e23e5	708	if (seq && ack) {} // shut up the compiler about unused variables
nixnax	142:54d1543e23e5	709	int flags = ((flagbitstcp[0]&1)<<8)\|flagbitstcp[1];
nixnax	142:54d1543e23e5	710	char flagInfo[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	711	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	712	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	713	memset(flagInfo,'.', 8); // fill string with "........"
nixnax	142:54d1543e23e5	714	flagInfo[8]=0; // null terminate string
nixnax	142:54d1543e23e5	715	if (flags & (1<<0)) flagInfo[7]='F';
nixnax	142:54d1543e23e5	716	if (flags & (1<<1)) flagInfo[6]='S';
nixnax	142:54d1543e23e5	717	if (flags & (1<<2)) flagInfo[5]='R';
nixnax	142:54d1543e23e5	718	if (flags & (1<<3)) flagInfo[4]='P';
nixnax	142:54d1543e23e5	719	if (flags & (1<<4)) flagInfo[3]='A';
nixnax	142:54d1543e23e5	720	if (flags & (1<<5)) flagInfo[2]='U';
nixnax	142:54d1543e23e5	721	if (flags & (1<<6)) flagInfo[1]='E';
nixnax	142:54d1543e23e5	722	if (flags & (1<<7)) flagInfo[0]='C';
nixnax	142:54d1543e23e5	723	#else
nixnax	142:54d1543e23e5	724	if (flags & (1<<4)) flagInfo[0]='A'; // choose the most important flag to print
nixnax	142:54d1543e23e5	725	if (flags & (1<<1)) flagInfo[0]='S';
nixnax	142:54d1543e23e5	726	if (flags & (1<<0)) flagInfo[0]='F';
nixnax	142:54d1543e23e5	727	if (flags & (1<<3)) flagInfo[0]='P';
nixnax	142:54d1543e23e5	728	if (flags & (1<<2)) flagInfo[0]='R';
nixnax	142:54d1543e23e5	729	flagInfo[1]=0; // ' '
nixnax	142:54d1543e23e5	730	flagInfo[2]=0;
nixnax	142:54d1543e23e5	731	#endif
nixnax	142:54d1543e23e5	732	putsWhileCheckingInput( flagInfo );
nixnax	142:54d1543e23e5	733	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	734	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	735	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	142:54d1543e23e5	736	#endif
nixnax	142:54d1543e23e5	737	if( outGoing && ( flags == 0x11 ) ) { // ACK/FIN - if this is an outgoing ACK/FIN its the end of a tcp conversation
nixnax	142:54d1543e23e5	738	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end of an HTTP the conversation
nixnax	142:54d1543e23e5	739	}
nixnax	142:54d1543e23e5	740	#endif
nixnax	142:54d1543e23e5	741	}
nixnax	142:54d1543e23e5	742
nixnax	143:c5019f856a56	743	/// Encode a buffer in base-64
nixnax	142:54d1543e23e5	744	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	745	{
nixnax	142:54d1543e23e5	746	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	747	int i,j,a,b,c;
nixnax	142:54d1543e23e5	748	i=0;
nixnax	142:54d1543e23e5	749	j=0;
nixnax	142:54d1543e23e5	750	while(1) {
nixnax	142:54d1543e23e5	751	if (i<len) {
nixnax	142:54d1543e23e5	752	a = in[i++];
nixnax	142:54d1543e23e5	753	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	754	} else break;
nixnax	142:54d1543e23e5	755	if (i<len) {
nixnax	142:54d1543e23e5	756	b = in[i++];
nixnax	142:54d1543e23e5	757	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	758	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	759	} else out[j++] = '=';
nixnax	142:54d1543e23e5	760	if (i<len) {
nixnax	142:54d1543e23e5	761	c = in[i++];
nixnax	142:54d1543e23e5	762	j--;
nixnax	142:54d1543e23e5	763	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	764	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	765	} else out[j++] = '=';
nixnax	142:54d1543e23e5	766	}
nixnax	142:54d1543e23e5	767	out[j]=0;
nixnax	142:54d1543e23e5	768	}
nixnax	142:54d1543e23e5	769
nixnax	142:54d1543e23e5	770	/// handle a request for an http websocket
nixnax	142:54d1543e23e5	771	/// 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	772	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	773	{
nixnax	142:54d1543e23e5	774	int n=0; // byte counter
nixnax	142:54d1543e23e5	775	char * key = strstr(dataStart, "Sec-WebSocket-Key: "); // search for the key in the payload
nixnax	142:54d1543e23e5	776	if (key != NULL) {
nixnax	142:54d1543e23e5	777	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	142:54d1543e23e5	778	char challenge [70];
nixnax	142:54d1543e23e5	779	strncpy(challenge,key+19,70); // a local buffer
nixnax	142:54d1543e23e5	780	*strchr(challenge,'\r')=0; // insert null so we can use sprintf
nixnax	142:54d1543e23e5	781	strncat(challenge,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11",70); // append websocket gui code
nixnax	142:54d1543e23e5	782	char shaOutput [20]; // sha1 output
nixnax	142:54d1543e23e5	783	sha1( shaOutput, challenge, strlen(challenge));
nixnax	142:54d1543e23e5	784	char encOut[50];
nixnax	142:54d1543e23e5	785	enc64( shaOutput, encOut, 20);
nixnax	142:54d1543e23e5	786	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	787	char * version = challenge;
nixnax	142:54d1543e23e5	788	strncpy(version, versionstring,70); // copy version string
nixnax	142:54d1543e23e5	789	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	790	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	791	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	792	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	793	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	794	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	795	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	796	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	797	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	798	}
nixnax	142:54d1543e23e5	799	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	800	}
nixnax	142:54d1543e23e5	801
nixnax	142:54d1543e23e5	802	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	803	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	804	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	805	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	806	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	807
nixnax	142:54d1543e23e5	808	/// respond to an HTTP request
nixnax	142:54d1543e23e5	809	int httpResponse(char * dataStart)
nixnax	142:54d1543e23e5	810	{
nixnax	142:54d1543e23e5	811	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	812	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	142:54d1543e23e5	813	if (n>0) return n; // if it's a WebSocket we already have the response, so return
nixnax	142:54d1543e23e5	814
nixnax	142:54d1543e23e5	815	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	816	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	817	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	142:54d1543e23e5	818
nixnax	142:54d1543e23e5	819	ppp.httpPageCount++; // increment the number of frames we have made
nixnax	142:54d1543e23e5	820
nixnax	142:54d1543e23e5	821	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	822	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	823	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	824	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	825	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	142:54d1543e23e5	826	if( (httpGetRoot==0) \|\| (httpGetx==0) ) {
nixnax	142:54d1543e23e5	827	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	828	} else {
nixnax	142:54d1543e23e5	829	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	830	}
nixnax	142:54d1543e23e5	831	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	832	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	833	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	834	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	142:54d1543e23e5	835	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	836	nHeader=n; // size of HTTP header
nixnax	142:54d1543e23e5	837	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	838	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	839	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	840	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	142:54d1543e23e5	841	} else if ( (httpGet5 == 'w') && (httpGet6 == 's') ) { // "ws" is a special page for websocket demo
nixnax	142:54d1543e23e5	842	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	843	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	142:54d1543e23e5	844	} else {
nixnax	142:54d1543e23e5	845	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	846
nixnax	142:54d1543e23e5	847	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	848	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	849	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	850	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	142:54d1543e23e5	851	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.httpPageCount); // body = the http frame count
nixnax	142:54d1543e23e5	852	#else
nixnax	142:54d1543e23e5	853	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	142:54d1543e23e5	854	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	855	}
nixnax	142:54d1543e23e5	856	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	142:54d1543e23e5	857	n=n+sprintf(n+dataStart,"%d ",ppp.httpPageCount); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	858	#endif
nixnax	142:54d1543e23e5	859	} else {
nixnax	142:54d1543e23e5	860	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	861	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	862	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	863	}
nixnax	142:54d1543e23e5	864	}
nixnax	142:54d1543e23e5	865	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	866	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	867	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	868	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	869	return n; // total byte size of our response
nixnax	142:54d1543e23e5	870	}
nixnax	142:54d1543e23e5	871
nixnax	142:54d1543e23e5	872	/// handle TCP data that is not an HTTP get
nixnax	142:54d1543e23e5	873	/// this is the response if we have TCP data but it's not an HTTP GET
nixnax	142:54d1543e23e5	874	/// this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax	142:54d1543e23e5	875	/// this could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	876	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	877	{
nixnax	142:54d1543e23e5	878	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	879	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	142:54d1543e23e5	880	// 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	881	if (0) putsWhileCheckingInput( "Got data from websocket send()\n" );
nixnax	142:54d1543e23e5	882
nixnax	142:54d1543e23e5	883	// for now we simply echo the websocket data back to the client - the client should therefore see an onmessage event
nixnax	142:54d1543e23e5	884	// 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	885	if (1) {
nixnax	142:54d1543e23e5	886	char mask [4];
nixnax	142:54d1543e23e5	887	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	142:54d1543e23e5	888	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	142:54d1543e23e5	889	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	890	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	891	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	892	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	142:54d1543e23e5	893	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	894	}
nixnax	142:54d1543e23e5	895	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	896	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	897	dataStart[1]=0; // we don't have mask bytes on
nixnax	142:54d1543e23e5	898	} else if (v1) putsWhileCheckingInput("TCP data received\n");
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 an incoming TCP packet
nixnax	142:54d1543e23e5	903	/// 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	904	void tcpHandler()
nixnax	142:54d1543e23e5	905	{
nixnax	142:54d1543e23e5	906	// IP header
nixnax	142:54d1543e23e5	907	char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax	142:54d1543e23e5	908	char * ihl = ipPkt; // bottom 4 bits
nixnax	142:54d1543e23e5	909	char * pktLen = ipPkt+2; // 2 bytes
nixnax	142:54d1543e23e5	910	char * ident = ipPkt+4; // 2 bytes
nixnax	142:54d1543e23e5	911	char * protocol = ipPkt+9; // 1 byte
nixnax	142:54d1543e23e5	912	char * headercheck= ipPkt+10; // 2 bytes
nixnax	142:54d1543e23e5	913	char * srcAdr = ipPkt+12; // 4 bytes
nixnax	142:54d1543e23e5	914	char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax	142:54d1543e23e5	915	int headerSizeIP = (ihl[0]&0xf)*4;
nixnax	142:54d1543e23e5	916	int packetLength = (pktLen[0]<<8)\|pktLen[1]; // ip total packet length
nixnax	142:54d1543e23e5	917
nixnax	142:54d1543e23e5	918	// TCP header
nixnax	142:54d1543e23e5	919	char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax	142:54d1543e23e5	920	char * srctcp = tcp + 0; // 2 bytes
nixnax	142:54d1543e23e5	921	char * dsttcp = tcp + 2; // 2 bytes
nixnax	142:54d1543e23e5	922	char * seqtcp = tcp + 4; // 4 bytes
nixnax	142:54d1543e23e5	923	char * acktcp = tcp + 8; // 4 bytes
nixnax	142:54d1543e23e5	924	char * offset = tcp + 12; // 4 bits
nixnax	142:54d1543e23e5	925	char * flagbitstcp = tcp + 12; // 9 bits
nixnax	142:54d1543e23e5	926	char * windowsizetcp = tcp + 14; // 2 bytes
nixnax	142:54d1543e23e5	927	char * checksumtcp = tcp + 16; // 2 bytes
nixnax	142:54d1543e23e5	928
nixnax	142:54d1543e23e5	929	if(ident) {}; // shut up unused variable reference warning
nixnax	142:54d1543e23e5	930	int tcpSize = packetLength - headerSizeIP;
nixnax	142:54d1543e23e5	931	int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax	142:54d1543e23e5	932	int protocolIP = protocol[0];
nixnax	142:54d1543e23e5	933	char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax	142:54d1543e23e5	934	int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax	142:54d1543e23e5	935	char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax	142:54d1543e23e5	936	unsigned int seq_in = (seqtcp[0]<<24)\|(seqtcp[1]<<16)\|(seqtcp[2]<<8)\|(seqtcp[3]);
nixnax	142:54d1543e23e5	937	unsigned int ack_in = (acktcp[0]<<24)\|(acktcp[1]<<16)\|(acktcp[2]<<8)\|(acktcp[3]);
nixnax	142:54d1543e23e5	938	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	939	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	940
nixnax	142:54d1543e23e5	941	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	142:54d1543e23e5	942	tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	142:54d1543e23e5	943	headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax	142:54d1543e23e5	944	offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax	142:54d1543e23e5	945	packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	142:54d1543e23e5	946	pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	142:54d1543e23e5	947	pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax	142:54d1543e23e5	948
nixnax	142:54d1543e23e5	949	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	950	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	142:54d1543e23e5	951	int flagsTCP = ((flagbitstcp[0]&1)<<8)\|flagbitstcp[1]; // the tcp flags we received
nixnax	142:54d1543e23e5	952	windowsizetcp[0] = (700 >> 8 ); // tcp window size hi byte
nixnax	142:54d1543e23e5	953	windowsizetcp[1] = (700 & 0xff); // tcp window size lo byte
nixnax	142:54d1543e23e5	954
nixnax	142:54d1543e23e5	955	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	956
nixnax	142:54d1543e23e5	957	switch ( flagsTCP ) {
nixnax	142:54d1543e23e5	958	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	959	return;
nixnax	142:54d1543e23e5	960	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	961	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	962	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	963	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	964	break;
nixnax	142:54d1543e23e5	965	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	142:54d1543e23e5	966	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	142:54d1543e23e5	967	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	968	dataLen = httpResponse(tcpDataOut); // send an http response
nixnax	142:54d1543e23e5	969	} else {
nixnax	142:54d1543e23e5	970	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not a web request, send a packet reporting number of received bytes
nixnax	142:54d1543e23e5	971	}
nixnax	142:54d1543e23e5	972	break;
nixnax	142:54d1543e23e5	973	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	974	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	975	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	976	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	977	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	978	break;
nixnax	142:54d1543e23e5	979	default:
nixnax	142:54d1543e23e5	980	return; // ignore remaining packets
nixnax	142:54d1543e23e5	981	} // switch
nixnax	142:54d1543e23e5	982
nixnax	142:54d1543e23e5	983	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	984	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	142:54d1543e23e5	985	char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax	142:54d1543e23e5	986	memcpy(tempHold, srcAdr,4);
nixnax	142:54d1543e23e5	987	memcpy(srcAdr, dstAdr,4);
nixnax	142:54d1543e23e5	988	memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax	142:54d1543e23e5	989	memcpy(tempHold, srctcp,2);
nixnax	142:54d1543e23e5	990	memcpy(srctcp, dsttcp,2);
nixnax	142:54d1543e23e5	991	memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax	142:54d1543e23e5	992
nixnax	142:54d1543e23e5	993	acktcp[0]=ack_out>>24;
nixnax	142:54d1543e23e5	994	acktcp[1]=ack_out>>16;
nixnax	142:54d1543e23e5	995	acktcp[2]=ack_out>>8;
nixnax	142:54d1543e23e5	996	acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax	142:54d1543e23e5	997	seqtcp[0]=seq_out>>24;
nixnax	142:54d1543e23e5	998	seqtcp[1]=seq_out>>16;
nixnax	142:54d1543e23e5	999	seqtcp[2]=seq_out>>8;
nixnax	142:54d1543e23e5	1000	seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax	142:54d1543e23e5	1001
nixnax	142:54d1543e23e5	1002	flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1003
nixnax	142:54d1543e23e5	1004	// increment our outgoing ip packet counter
nixnax	142:54d1543e23e5	1005	ppp.ip.ident++; // get next ident number for our packet
nixnax	142:54d1543e23e5	1006
nixnax	142:54d1543e23e5	1007	// Now we recalculate all the header sizes
nixnax	142:54d1543e23e5	1008	tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax	142:54d1543e23e5	1009	int newPacketSize = headerSizeIP + tcpSize; // calculate size of the outgoing packet
nixnax	142:54d1543e23e5	1010	pktLen[0] = (newPacketSize>>8);
nixnax	142:54d1543e23e5	1011	pktLen[1]=newPacketSize; // ip total packet size
nixnax	142:54d1543e23e5	1012	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	1013
nixnax	142:54d1543e23e5	1014	// the header is all set up, now do the IP and TCP checksums
nixnax	142:54d1543e23e5	1015	headercheck[0]=0; // IP header checksum
nixnax	142:54d1543e23e5	1016	headercheck[1]=0; // IP header checksum
nixnax	142:54d1543e23e5	1017	headerCheckSum(); // calculate the IP header checksum
nixnax	142:54d1543e23e5	1018
nixnax	142:54d1543e23e5	1019	// 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	1020	// this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax	142:54d1543e23e5	1021	char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax	142:54d1543e23e5	1022	memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax	142:54d1543e23e5	1023	memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax	142:54d1543e23e5	1024	memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax	142:54d1543e23e5	1025	memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax	142:54d1543e23e5	1026	memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax	142:54d1543e23e5	1027	memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax	142:54d1543e23e5	1028
nixnax	142:54d1543e23e5	1029	// pseudo-header built, now we can calculate TCP checksum
nixnax	142:54d1543e23e5	1030	checksumtcp[0]=0;
nixnax	142:54d1543e23e5	1031	checksumtcp[1]=0;
nixnax	142:54d1543e23e5	1032	unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax	142:54d1543e23e5	1033	checksumtcp[0]=pseudoHeaderSum>>8;
nixnax	142:54d1543e23e5	1034	checksumtcp[1]=pseudoHeaderSum;
nixnax	142:54d1543e23e5	1035	memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax	142:54d1543e23e5	1036	dumpHeaderIP(1); // dump outgoing IP header
nixnax	142:54d1543e23e5	1037	dumpHeaderTCP(1); // dump outgoing TCP header
nixnax	142:54d1543e23e5	1038	for (int i=0; i<45*1000/10; i++) { // 45 ms delay before sending frame - a typical internet delay time
nixnax	142:54d1543e23e5	1039	checkPc(); // catch any incoming characters
nixnax	142:54d1543e23e5	1040	wait_us(10); // wait less than 1 character duration at 115200
nixnax	142:54d1543e23e5	1041	}
nixnax	144:01d98cf7738e	1042	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1043	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1044	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1045	}
nixnax	142:54d1543e23e5	1046
nixnax	142:54d1543e23e5	1047
nixnax	142:54d1543e23e5	1048	/// dump the TCP data to the debug serial port
nixnax	142:54d1543e23e5	1049	void dumpDataTCP()
nixnax	142:54d1543e23e5	1050	{
nixnax	142:54d1543e23e5	1051	int ipPktLen = (ppp.pkt.buf[6]<<8)\|ppp.pkt.buf[7]; // overall length of ip packet
nixnax	142:54d1543e23e5	1052	int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax	142:54d1543e23e5	1053	int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax	142:54d1543e23e5	1054	int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax	142:54d1543e23e5	1055	if (v1) {
nixnax	142:54d1543e23e5	1056	char pbuf[50]; // local print buffer
nixnax	142:54d1543e23e5	1057	checkPc();
nixnax	142:54d1543e23e5	1058	sprintf(pbuf, "TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax	142:54d1543e23e5	1059	checkPc();
nixnax	142:54d1543e23e5	1060	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	1061	}
nixnax	142:54d1543e23e5	1062	if (dataLen > 0) {
nixnax	142:54d1543e23e5	1063	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	1064	putsWhileCheckingInput( ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP ); // print the tcp payload data
nixnax	142:54d1543e23e5	1065	putsWhileCheckingInput("\n");
nixnax	142:54d1543e23e5	1066	}
nixnax	142:54d1543e23e5	1067	}
nixnax	142:54d1543e23e5	1068
nixnax	142:54d1543e23e5	1069	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1070	void TCPpacket()
nixnax	142:54d1543e23e5	1071	{
nixnax	142:54d1543e23e5	1072	dumpHeaderIP(0); // dump incoming packet header
nixnax	142:54d1543e23e5	1073	dumpHeaderTCP(0); // dump incoming packet header
nixnax	142:54d1543e23e5	1074	if (v2) dumpDataTCP();
nixnax	142:54d1543e23e5	1075	tcpHandler();
nixnax	142:54d1543e23e5	1076	}
nixnax	142:54d1543e23e5	1077
nixnax	142:54d1543e23e5	1078	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1079	void otherProtocol()
nixnax	142:54d1543e23e5	1080	{
nixnax	142:54d1543e23e5	1081	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1082	}
nixnax	142:54d1543e23e5	1083
nixnax	142:54d1543e23e5	1084	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1085	void IPframe()
nixnax	142:54d1543e23e5	1086	{
nixnax	142:54d1543e23e5	1087	int protocol = ppp.pkt.buf[13];
nixnax	142:54d1543e23e5	1088	switch (protocol) {
nixnax	142:54d1543e23e5	1089	case 1:
nixnax	142:54d1543e23e5	1090	ICMPpacket();
nixnax	142:54d1543e23e5	1091	break;
nixnax	142:54d1543e23e5	1092	case 2:
nixnax	142:54d1543e23e5	1093	IGMPpacket();
nixnax	142:54d1543e23e5	1094	break;
nixnax	142:54d1543e23e5	1095	case 17:
nixnax	142:54d1543e23e5	1096	UDPpacket();
nixnax	142:54d1543e23e5	1097	break;
nixnax	142:54d1543e23e5	1098	case 6:
nixnax	142:54d1543e23e5	1099	TCPpacket();
nixnax	142:54d1543e23e5	1100	break;
nixnax	142:54d1543e23e5	1101	default:
nixnax	142:54d1543e23e5	1102	otherProtocol();
nixnax	142:54d1543e23e5	1103	}
nixnax	142:54d1543e23e5	1104	}
nixnax	142:54d1543e23e5	1105
nixnax	142:54d1543e23e5	1106	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1107	void LCPconfReq()
nixnax	142:54d1543e23e5	1108	{
nixnax	142:54d1543e23e5	1109	debugPrintf("LCP Config ");
nixnax	142:54d1543e23e5	1110	if (ppp.pkt.buf[7] != 4) {
nixnax	142:54d1543e23e5	1111	ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1112	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1113	sendPppFrame();
nixnax	142:54d1543e23e5	1114	} else {
nixnax	142:54d1543e23e5	1115	ppp.pkt.buf[4]=2; // ack zero conf
nixnax	142:54d1543e23e5	1116	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1117	sendPppFrame();
nixnax	142:54d1543e23e5	1118	debugPrintf("LCP Ask\n");
nixnax	142:54d1543e23e5	1119	ppp.pkt.buf[4]=1; // request no options
nixnax	144:01d98cf7738e	1120	sendPppFrame();
nixnax	142:54d1543e23e5	1121	}
nixnax	142:54d1543e23e5	1122	}
nixnax	142:54d1543e23e5	1123
nixnax	142:54d1543e23e5	1124	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1125	void LCPconfAck()
nixnax	142:54d1543e23e5	1126	{
nixnax	142:54d1543e23e5	1127	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1128	}
nixnax	142:54d1543e23e5	1129
nixnax	143:c5019f856a56	1130	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1131	void LCPend()
nixnax	142:54d1543e23e5	1132	{
nixnax	142:54d1543e23e5	1133	ppp.pkt.buf[4]=6;
nixnax	144:01d98cf7738e	1134	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1135	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1136	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1137	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1138	}
nixnax	142:54d1543e23e5	1139
nixnax	142:54d1543e23e5	1140	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1141	void LCPother()
nixnax	142:54d1543e23e5	1142	{
nixnax	142:54d1543e23e5	1143	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1144	dumpPPPFrame();
nixnax	142:54d1543e23e5	1145	}
nixnax	142:54d1543e23e5	1146
nixnax	142:54d1543e23e5	1147	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1148	void LCPframe()
nixnax	142:54d1543e23e5	1149	{
nixnax	142:54d1543e23e5	1150	int code = ppp.pkt.buf[4];
nixnax	142:54d1543e23e5	1151	switch (code) {
nixnax	142:54d1543e23e5	1152	case 1:
nixnax	142:54d1543e23e5	1153	LCPconfReq();
nixnax	142:54d1543e23e5	1154	break; // config request
nixnax	142:54d1543e23e5	1155	case 2:
nixnax	142:54d1543e23e5	1156	LCPconfAck();
nixnax	142:54d1543e23e5	1157	break; // config ack
nixnax	142:54d1543e23e5	1158	case 5:
nixnax	142:54d1543e23e5	1159	LCPend();
nixnax	142:54d1543e23e5	1160	break; // end connection
nixnax	142:54d1543e23e5	1161	default:
nixnax	142:54d1543e23e5	1162	LCPother();
nixnax	142:54d1543e23e5	1163	}
nixnax	142:54d1543e23e5	1164	}
nixnax	142:54d1543e23e5	1165
nixnax	142:54d1543e23e5	1166	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1167	void discardedFrame()
nixnax	142:54d1543e23e5	1168	{
nixnax	142:54d1543e23e5	1169	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	1170	}
nixnax	142:54d1543e23e5	1171
nixnax	142:54d1543e23e5	1172	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1173	void determinePacketType()
nixnax	142:54d1543e23e5	1174	{
nixnax	142:54d1543e23e5	1175	if ( ppp.pkt.buf[0] != 0xff ) {
nixnax	142:54d1543e23e5	1176	debugPrintf("byte0 != ff\n");
nixnax	142:54d1543e23e5	1177	return;
nixnax	142:54d1543e23e5	1178	}
nixnax	142:54d1543e23e5	1179	if ( ppp.pkt.buf[1] != 3 ) {
nixnax	142:54d1543e23e5	1180	debugPrintf("byte1 != 3\n");
nixnax	142:54d1543e23e5	1181	return;
nixnax	142:54d1543e23e5	1182	}
nixnax	142:54d1543e23e5	1183	if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax	142:54d1543e23e5	1184	debugPrintf("byte2 != 21\n");
nixnax	142:54d1543e23e5	1185	return;
nixnax	142:54d1543e23e5	1186	}
nixnax	142:54d1543e23e5	1187	int packetType = ppp.pkt.buf[2];
nixnax	142:54d1543e23e5	1188	switch (packetType) {
nixnax	142:54d1543e23e5	1189	case 0xc0:
nixnax	142:54d1543e23e5	1190	LCPframe();
nixnax	142:54d1543e23e5	1191	break; // link control
nixnax	142:54d1543e23e5	1192	case 0x80:
nixnax	142:54d1543e23e5	1193	IPCPframe();
nixnax	142:54d1543e23e5	1194	break; // IP control
nixnax	142:54d1543e23e5	1195	case 0x00:
nixnax	142:54d1543e23e5	1196	IPframe();
nixnax	142:54d1543e23e5	1197	break; // IP itself
nixnax	142:54d1543e23e5	1198	default:
nixnax	142:54d1543e23e5	1199	discardedFrame();
nixnax	142:54d1543e23e5	1200	}
nixnax	142:54d1543e23e5	1201	}
nixnax	142:54d1543e23e5	1202
nixnax	142:54d1543e23e5	1203	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1204	void waitForPppFrame()
nixnax	142:54d1543e23e5	1205	{
nixnax	142:54d1543e23e5	1206	while(1) {
nixnax	142:54d1543e23e5	1207	checkPc(); // handle received characters
nixnax	142:54d1543e23e5	1208	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1209	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1210	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1211	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1212	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1213	ppp.firstFrame=0;
nixnax	142:54d1543e23e5	1214	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1215	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	142:54d1543e23e5	1216	} else {
nixnax	142:54d1543e23e5	1217	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1218	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1219	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1220	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1221	break;
nixnax	142:54d1543e23e5	1222	}
nixnax	142:54d1543e23e5	1223	}
nixnax	142:54d1543e23e5	1224	}
nixnax	142:54d1543e23e5	1225	}
nixnax	142:54d1543e23e5	1226	}
nixnax	142:54d1543e23e5	1227
nixnax	142:54d1543e23e5	1228	/// 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	1229	void scanForConnectString()
nixnax	142:54d1543e23e5	1230	{
nixnax	142:54d1543e23e5	1231	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1232	checkPc(); // gather received characters
nixnax	142:54d1543e23e5	1233	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1234	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1235	if (found1 != NULL) {
nixnax	142:54d1543e23e5	1236	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	143:c5019f856a56	1237	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	142:54d1543e23e5	1238	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1239	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1240	checkPc();
nixnax	142:54d1543e23e5	1241	}
nixnax	142:54d1543e23e5	1242	}
nixnax	142:54d1543e23e5	1243	}
nixnax	142:54d1543e23e5	1244
nixnax	144:01d98cf7738e	1245	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1246	void initializePpp()
nixnax	142:54d1543e23e5	1247	{
nixnax	142:54d1543e23e5	1248	pc.baud(115200); // USB serial port to pc
nixnax	144:01d98cf7738e	1249	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	142:54d1543e23e5	1250	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	1251	pppInitStruct(); // initialize all the PPP properties
nixnax	143:c5019f856a56	1252	}

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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.