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@220:54f45f924707, 2018-08-20 (annotated)

Committer:: nixnax
Date:: Mon Aug 20 05:29:29 2018 +0000
Revision:: 220:54f45f924707
Parent:: 219:cbf6a235d1f2
Child:: 221:1d7c32d8256b

Unrolled the CRC calculation.

Who changed what in which revision?

User	Revision	Line number	New contents of line
nixnax	182:f039ec218c9f	1	// PPP-Blinky - "The Most Basic Internet Thing"
nixnax	142:54d1543e23e5	2	// A Tiny HTTP Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax	142:54d1543e23e5	3	// Receives UDP packets and responds to ping (ICMP Echo requests)
nixnax	142:54d1543e23e5	4	// WebSocket Service - see https://en.wikipedia.org/wiki/WebSocket
nixnax	142:54d1543e23e5	5
nixnax	142:54d1543e23e5	6	// Copyright 2016/2017 Nicolas Nackel aka Nixnax. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nixnax	142:54d1543e23e5	7
nixnax	142:54d1543e23e5	8	// Notes and Instructions
nixnax	142:54d1543e23e5	9	// http://bit.ly/PPP-Blinky-Instructions
nixnax	142:54d1543e23e5	10	// http://bit.ly/win-rasdial-config
nixnax	142:54d1543e23e5	11
nixnax	201:9fcf92e9f427	12	// Important - ensure that you are using the latest mbed firmware for your specific mbed target board
nixnax	201:9fcf92e9f427	13
nixnax	142:54d1543e23e5	14	// Handy reading material
nixnax	142:54d1543e23e5	15	// https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax	142:54d1543e23e5	16	// https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax	142:54d1543e23e5	17	// http://atari.kensclassics.org/wcomlog.htm
nixnax	142:54d1543e23e5	18
nixnax	142:54d1543e23e5	19	// Handy tools
nixnax	142:54d1543e23e5	20	// https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax	142:54d1543e23e5	21	// https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax	142:54d1543e23e5	22	// http://pingtester.net/ - nice tool for high rate ping testing
nixnax	142:54d1543e23e5	23	// http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax	142:54d1543e23e5	24	// https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax	142:54d1543e23e5	25	// https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax	142:54d1543e23e5	26	// Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax	142:54d1543e23e5	27
nixnax	142:54d1543e23e5	28	// Connecting PPP-Blinky to Linux
nixnax	142:54d1543e23e5	29	// PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax	142:54d1543e23e5	30	// pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax	142:54d1543e23e5	31	// in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax	142:54d1543e23e5	32	// See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax	142:54d1543e23e5	33
nixnax	142:54d1543e23e5	34	// Special pages when PPP-Blinky is running
nixnax	142:54d1543e23e5	35	// 172.10.10.2 root page
nixnax	182:f039ec218c9f	36	// 172.10.10.2/x returns the number of ppp frames sent - this is handy for testing
nixnax	182:f039ec218c9f	37	// 172.10.10.2/xb also returns number of ppp frames sent, but issues a fast refresh meta command. This allows you to use your browser to benchmark page load speed
nixnax	142:54d1543e23e5	38	// 172.10.10.2/ws a simple WebSocket demo
nixnax	182:f039ec218c9f	39	// http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle, showing cross-domain access
nixnax	207:28cd834b785d	40
nixnax	142:54d1543e23e5	41	// Ok, enough talking, time to check out some code!!
nixnax	142:54d1543e23e5	42
nixnax	142:54d1543e23e5	43	#include "ppp-blinky.h"
nixnax	142:54d1543e23e5	44
nixnax	142:54d1543e23e5	45	// The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax	146:a45f49a2b29c	46	// Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor the debug output.
nixnax	142:54d1543e23e5	47	// Using the second serial port will slow down packet response time
nixnax	142:54d1543e23e5	48	// Note - the LPC11U24 does NOT have a second serial port
nixnax	146:a45f49a2b29c	49
nixnax	183:6d3ba874b267	50	#define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax	142:54d1543e23e5	51
nixnax	142:54d1543e23e5	52	// here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax	142:54d1543e23e5	53	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	54	#if defined(TARGET_LPC1768)
nixnax	179:ba2b2ddd0da5	55	RawSerial xx(p9, p10); // Second serial port on LPC1768 - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	56	#elif defined(TARGET_NUCLEO_F446RE) \|\| defined(TARGET_NUCLEO_L152RE) \|\| defined(TARGET_NUCLEO_L053R8) \|\| defined(TARGET_NUCLEO_L476RG) \|\| defined(TARGET_NUCLEO_F401RE)
nixnax	179:ba2b2ddd0da5	57	RawSerial xx(PC_10, PC_11); // Second serial port on NUCLEO boards - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	196:8791e241be80	58	#elif defined(TARGET_NUCLEO_L432KC)
nixnax	196:8791e241be80	59	RawSerial xx(PA_9, PA_10); // Second serial port on NUCLEO-L432KC - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	60	#elif defined(TARGET_LPC11U24)
nixnax	142:54d1543e23e5	61	#error The LPC11U24 does not have a second serial port to use for debugging - change SERIAL_PORT_MONITOR_YES back to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	62	#elif defined (TARGET_KL46Z) \|\| (TARGET_KL25Z)
nixnax	179:ba2b2ddd0da5	63	RawSerial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax	193:48072570f41d	64	#elif defined(TARGET_KW41Z)
nixnax	194:5b23ebfb3626	65	RawSerial xx(PTC3, PTC2); // Second serial port on FRDM-KW41Z board
nixnax	142:54d1543e23e5	66	#elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax	142:54d1543e23e5	67	// change the next line to YOUR target board's second serial port pin definition if it's not present - and if it works, please send it to me - thanks!!!
nixnax	179:ba2b2ddd0da5	68	RawSerial xx(p9, p10); // change this to YOUR board second serial port pin definition - and please send it to me if it works!!!
nixnax	142:54d1543e23e5	69	#else
nixnax	142:54d1543e23e5	70	#error Add your target board's second serial port here if you want to use debugging - or simply change SERIAL_PORT_MONITOR_YES to SERIAL_PORT_MONITOR_NO
nixnax	142:54d1543e23e5	71	#endif
nixnax	179:ba2b2ddd0da5	72	#define debugPrintf(x...) xx.printf (x) /* if we have a serial port we can print debug messages */
nixnax	142:54d1543e23e5	73	#define debugPutc(x...) xx.putc(x)
nixnax	142:54d1543e23e5	74	#define debugBaudRate(x...) xx.baud(x)
nixnax	142:54d1543e23e5	75	#else
nixnax	142:54d1543e23e5	76	// if we don't have a debug port the debug print functions do nothing
nixnax	142:54d1543e23e5	77	#define debugPrintf(x...) {}
nixnax	142:54d1543e23e5	78	#define debugPutc(x...) {}
nixnax	142:54d1543e23e5	79	#define debugBaudRate(x...) {}
nixnax	142:54d1543e23e5	80	#endif
nixnax	142:54d1543e23e5	81
nixnax	142:54d1543e23e5	82	// verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax	182:f039ec218c9f	83	#define v0 1
nixnax	142:54d1543e23e5	84	#define v1 0
nixnax	142:54d1543e23e5	85	#define v2 0
nixnax	182:f039ec218c9f	86	#define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax	182:f039ec218c9f	87	#define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax	142:54d1543e23e5	88
nixnax	142:54d1543e23e5	89	// this is the webpage we serve when we get an HTTP request to root (/)
nixnax	142:54d1543e23e5	90	// keep size under ~900 bytes to fit into a single PPP packet
nixnax	142:54d1543e23e5	91
nixnax	142:54d1543e23e5	92	const static char rootWebPage[] = "\
nixnax	142:54d1543e23e5	93	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	94	<html>\
nixnax	142:54d1543e23e5	95	<head>\
nixnax	146:a45f49a2b29c	96	<title>mbed PPP-Blinky</title>\r\n\
nixnax	142:54d1543e23e5	97	</head>\
nixnax	142:54d1543e23e5	98	<body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax	142:54d1543e23e5	99	<h1>mbed PPP-Blinky Up and Running</h1>\
nixnax	142:54d1543e23e5	100	<h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax	210:a2a651249a9a	101	<h1><a href=\"/w\">WebSocket Test</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	219:cbf6a235d1f2	104	<h1><a href=\"http://jsfiddle.net/d26cyuh2/21\">JSFiddle Demo</a></h1>\
nixnax	142:54d1543e23e5	105	</body>\
nixnax	210:a2a651249a9a	106	</html>\r\n"; // size = 451 bytes + 1 null byte = 452 bytes
nixnax	142:54d1543e23e5	107
nixnax	167:ff8a2d8beeb1	108	// this is a websocket demo html page we serve when GET /ws is requested
nixnax	142:54d1543e23e5	109	const static char webSocketPage[] = "\
nixnax	142:54d1543e23e5	110	<!DOCTYPE html>\
nixnax	142:54d1543e23e5	111	<html>\
nixnax	142:54d1543e23e5	112	<head>\
nixnax	142:54d1543e23e5	113	<title>mbed PPP-Blinky</title>\
nixnax	142:54d1543e23e5	114	<script>\
nixnax	142:54d1543e23e5	115	window.onload=function(){\
nixnax	142:54d1543e23e5	116	var url=\"ws://172.10.10.2\";\
nixnax	142:54d1543e23e5	117	var sts=document.getElementById(\"sts\");\
nixnax	142:54d1543e23e5	118	var btn=document.getElementById(\"btn\");\
nixnax	142:54d1543e23e5	119	var ctr=0;\
nixnax	142:54d1543e23e5	120	function show(text){sts.textContent=text;}\
nixnax	142:54d1543e23e5	121	btn.onclick=function(){\
nixnax	142:54d1543e23e5	122	if(btn.textContent==\"Connect\"){\
nixnax	142:54d1543e23e5	123	x=new WebSocket(url);\
nixnax	142:54d1543e23e5	124	x.onopen=function(){\
nixnax	142:54d1543e23e5	125	show(\"Connected to : \"+url);\
nixnax	142:54d1543e23e5	126	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	127	};\
nixnax	142:54d1543e23e5	128	x.onclose=function(){show(\"closed\");};\
nixnax	142:54d1543e23e5	129	x.onmessage=function(msg){show(\"PPP-Blinky Sent: \\\"\"+msg.data+\"\\\"\");};\
nixnax	142:54d1543e23e5	130	} else {\
nixnax	142:54d1543e23e5	131	x.send(ctr);\
nixnax	142:54d1543e23e5	132	ctr=ctr+1;\
nixnax	142:54d1543e23e5	133	btn.textContent=\"Send \\\"\"+ctr+\"\\\"\";\
nixnax	142:54d1543e23e5	134	}\
nixnax	142:54d1543e23e5	135	};\
nixnax	142:54d1543e23e5	136	};\
nixnax	142:54d1543e23e5	137	</script>\
nixnax	142:54d1543e23e5	138	<body style=\"font-family: sans-serif; font-size:25px; color:#807070\">\
nixnax	142:54d1543e23e5	139	<h1>PPP-Blinky WebSocket Test</h1>\
nixnax	142:54d1543e23e5	140	<div id=\"sts\">Idle</div>\
nixnax	142:54d1543e23e5	141	<button id=\"btn\" style=\"font-size: 100%; margin-top: 55px; margin-bottom: 55px;\">Connect</button>\
nixnax	142:54d1543e23e5	142	<h4><a href=\"/\">PPP-Blinky home</a></h4>\
nixnax	142:54d1543e23e5	143	</body>\
nixnax	142:54d1543e23e5	144	</html>"; // size = 916 bytes + 1 null byte = 917 bytes
nixnax	142:54d1543e23e5	145
nixnax	142:54d1543e23e5	146	// 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	147	// On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax	142:54d1543e23e5	148	// The modem baud rate should be set to 115200 baud
nixnax	142:54d1543e23e5	149	// See instructions at the top.
nixnax	142:54d1543e23e5	150	// On a typical mbed hardware platform this serial port is a USB virtual com port (VCP) and the USB serial driver is supplied by the board vendor.
nixnax	179:ba2b2ddd0da5	151	RawSerial pc (USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax	142:54d1543e23e5	152
nixnax	142:54d1543e23e5	153	DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax	142:54d1543e23e5	154
nixnax	142:54d1543e23e5	155	// the standard hdlc frame start/end character. It's the tilde character "~"
nixnax	142:54d1543e23e5	156	#define FRAME_7E (0x7e)
nixnax	142:54d1543e23e5	157
nixnax	142:54d1543e23e5	158	pppType ppp; // our global - definitely not thread safe
nixnax	142:54d1543e23e5	159
nixnax	142:54d1543e23e5	160	/// Initialize the ppp structure and clear the receive buffer
nixnax	142:54d1543e23e5	161	void pppInitStruct()
nixnax	142:54d1543e23e5	162	{
nixnax	209:aa514cd631ee	163	memset( ppp.rx.buf, 0, RXBUFLEN+1); // one extra byte at the end which always remains zero so strstr() cannot exceed the buffer
nixnax	142:54d1543e23e5	164	ppp.online=0;
nixnax	142:54d1543e23e5	165	ppp.rx.tail=0;
nixnax	142:54d1543e23e5	166	ppp.rx.rtail=0;
nixnax	142:54d1543e23e5	167	ppp.rx.head=0;
nixnax	142:54d1543e23e5	168	ppp.rx.buflevel=0;
nixnax	209:aa514cd631ee	169	ppp.rx.maxbuflevel=0;
nixnax	142:54d1543e23e5	170	ppp.pkt.len=0;
nixnax	154:18b2bd92f557	171	ppp.ipData.ident=10000; // easy to recognize in ip packet dumps
nixnax	142:54d1543e23e5	172	ppp.ledState=0;
nixnax	142:54d1543e23e5	173	ppp.hdlc.frameStartIndex=0;
nixnax	146:a45f49a2b29c	174	ppp.responseCounter=0;
nixnax	142:54d1543e23e5	175	ppp.firstFrame=1;
nixnax	175:b4e6f8a6fe00	176	ppp.ppp = (pppHeaderType *)ppp.pkt.buf; // pointer to ppp header
nixnax	175:b4e6f8a6fe00	177	ppp.ip = (ipHeaderType *)(ppp.pkt.buf+4); // pointer to IP header
nixnax	142:54d1543e23e5	178	}
nixnax	142:54d1543e23e5	179
nixnax	142:54d1543e23e5	180	/// Toggle the LED on every second PPP packet received
nixnax	142:54d1543e23e5	181	void led1Toggle()
nixnax	142:54d1543e23e5	182	{
nixnax	142:54d1543e23e5	183	led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax	143:c5019f856a56	184	ppp.ledState++;
nixnax	142:54d1543e23e5	185	}
nixnax	142:54d1543e23e5	186
nixnax	179:ba2b2ddd0da5	187	/// Returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax	150:3366bf3d294e	188	int connectedPpp()
nixnax	142:54d1543e23e5	189	{
nixnax	142:54d1543e23e5	190	return ppp.online;
nixnax	143:c5019f856a56	191	}
nixnax	142:54d1543e23e5	192
nixnax	179:ba2b2ddd0da5	193	/// PPP serial port receive interrupt handler.
nixnax	143:c5019f856a56	194	/// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax	143:c5019f856a56	195	/// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax	179:ba2b2ddd0da5	196	void pppReceiveHandler()
nixnax	142:54d1543e23e5	197	{
nixnax	142:54d1543e23e5	198	char ch;
nixnax	179:ba2b2ddd0da5	199	while ( pc.readable() ) {
nixnax	216:e3c5a5b47295	200	int hd = (ppp.rx.head+1);
nixnax	216:e3c5a5b47295	201	if (hd > RXBUFLEN) hd=0; // increment/wrap head index
nixnax	142:54d1543e23e5	202	if ( hd == ppp.rx.rtail ) {
nixnax	213:8555b6a3355a	203	// debugPrintf("\nReceive buffer full\n");
nixnax	142:54d1543e23e5	204	return;
nixnax	142:54d1543e23e5	205	}
nixnax	142:54d1543e23e5	206	ch = pc.getc(); // read new character
nixnax	142:54d1543e23e5	207	ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax	209:aa514cd631ee	208	if (ch == 0x7E) { // check for ppp frame start character
nixnax	209:aa514cd631ee	209	if ( ppp.online == 0 ) { // check if we are offline
nixnax	209:aa514cd631ee	210	ppp.online = 1; // if we see a frame start character we immediately change status to online
nixnax	142:54d1543e23e5	211	}
nixnax	142:54d1543e23e5	212	}
nixnax	142:54d1543e23e5	213	ppp.rx.head = hd; // update head pointer
nixnax	142:54d1543e23e5	214	ppp.rx.buflevel++;
nixnax	209:aa514cd631ee	215	if ( ppp.rx.buflevel > ppp.rx.maxbuflevel ) {
nixnax	209:aa514cd631ee	216	ppp.rx.maxbuflevel = ppp.rx.buflevel; // remember the max size of rx buflevel
nixnax	209:aa514cd631ee	217	}
nixnax	142:54d1543e23e5	218	}
nixnax	142:54d1543e23e5	219	}
nixnax	142:54d1543e23e5	220
nixnax	142:54d1543e23e5	221	/// print to debug port while checking for incoming characters
nixnax	142:54d1543e23e5	222	void putcWhileCheckingInput( char outByte )
nixnax	142:54d1543e23e5	223	{
nixnax	142:54d1543e23e5	224	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	225	debugPutc( outByte );
nixnax	142:54d1543e23e5	226	#endif
nixnax	142:54d1543e23e5	227	}
nixnax	142:54d1543e23e5	228
nixnax	142:54d1543e23e5	229	/// puts to debug port while checking the PPP input stream
nixnax	142:54d1543e23e5	230	void putsWhileCheckingInput( char * data )
nixnax	142:54d1543e23e5	231	{
nixnax	142:54d1543e23e5	232	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	142:54d1543e23e5	233	char * nextChar = data;
nixnax	142:54d1543e23e5	234	while( *nextChar != 0 ) {
nixnax	142:54d1543e23e5	235	putcWhileCheckingInput( *nextChar ); // write one character to debug port while checking input
nixnax	142:54d1543e23e5	236	nextChar++;
nixnax	142:54d1543e23e5	237	}
nixnax	142:54d1543e23e5	238	#endif
nixnax	142:54d1543e23e5	239	}
nixnax	142:54d1543e23e5	240
nixnax	145:098b6ed2f7f2	241	/// Initialize the PPP FCS (frame check sequence) total
nixnax	145:098b6ed2f7f2	242	void fcsReset()
nixnax	142:54d1543e23e5	243	{
nixnax	145:098b6ed2f7f2	244	ppp.fcs=0xffff; // crc restart
nixnax	142:54d1543e23e5	245	}
nixnax	142:54d1543e23e5	246
nixnax	145:098b6ed2f7f2	247	/// update the cumulative PPP FCS (frame check sequence)
nixnax	145:098b6ed2f7f2	248	void fcsDo(int x)
nixnax	142:54d1543e23e5	249	{
nixnax	220:54f45f924707	250	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	251	x>>=1;
nixnax	220:54f45f924707	252	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	253	x>>=1;
nixnax	220:54f45f924707	254	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	255	x>>=1;
nixnax	220:54f45f924707	256	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	257	x>>=1;
nixnax	220:54f45f924707	258	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	259	x>>=1;
nixnax	220:54f45f924707	260	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	261	x>>=1;
nixnax	220:54f45f924707	262	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	263	x>>=1;
nixnax	220:54f45f924707	264	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1;
nixnax	220:54f45f924707	265	x>>=1;
nixnax	142:54d1543e23e5	266	}
nixnax	142:54d1543e23e5	267
nixnax	145:098b6ed2f7f2	268	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	269	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	270	{
nixnax	145:098b6ed2f7f2	271	fcsReset();
nixnax	145:098b6ed2f7f2	272	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	273	return ppp.fcs;
nixnax	142:54d1543e23e5	274	}
nixnax	142:54d1543e23e5	275
nixnax	142:54d1543e23e5	276	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	277	int pc_getBuf()
nixnax	142:54d1543e23e5	278	{
nixnax	142:54d1543e23e5	279	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	216:e3c5a5b47295	280	ppp.rx.tail=ppp.rx.tail+1;
nixnax	216:e3c5a5b47295	281	if (ppp.rx.tail > RXBUFLEN) ppp.rx.tail=0;
nixnax	142:54d1543e23e5	282	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	283	return x;
nixnax	142:54d1543e23e5	284	}
nixnax	142:54d1543e23e5	285
nixnax	142:54d1543e23e5	286	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	287	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	288	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	164:c3de3d212c4b	289	/// In WireShark, use "Import Hex File". Import options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	290	void dumpPPPFrame()
nixnax	142:54d1543e23e5	291	{
nixnax	142:54d1543e23e5	292	char pbuf[30];
nixnax	142:54d1543e23e5	293	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	210:a2a651249a9a	294
nixnax	142:54d1543e23e5	295	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	210:a2a651249a9a	296
nixnax	142:54d1543e23e5	297	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	298	}
nixnax	210:a2a651249a9a	299
nixnax	142:54d1543e23e5	300	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	210:a2a651249a9a	301
nixnax	142:54d1543e23e5	302	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	303	}
nixnax	142:54d1543e23e5	304
nixnax	142:54d1543e23e5	305	/// Process a received PPP frame
nixnax	142:54d1543e23e5	306	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	307	{
nixnax	142:54d1543e23e5	308	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	309	if(start==end) {
nixnax	142:54d1543e23e5	310	return; // empty frame
nixnax	142:54d1543e23e5	311	}
nixnax	145:098b6ed2f7f2	312	fcsReset();
nixnax	142:54d1543e23e5	313	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	314	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	315	int unstuff=0;
nixnax	142:54d1543e23e5	316	int idx = start;
nixnax	142:54d1543e23e5	317	while(1) {
nixnax	210:a2a651249a9a	318
nixnax	142:54d1543e23e5	319	if (unstuff==0) {
nixnax	142:54d1543e23e5	320	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	321	else {
nixnax	142:54d1543e23e5	322	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	323	ppp.pkt.len++;
nixnax	142:54d1543e23e5	324	dest++;
nixnax	145:098b6ed2f7f2	325	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	326	}
nixnax	142:54d1543e23e5	327	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	328	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	329	ppp.pkt.len++;
nixnax	142:54d1543e23e5	330	dest++;
nixnax	145:098b6ed2f7f2	331	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	332	unstuff=0;
nixnax	142:54d1543e23e5	333	}
nixnax	216:e3c5a5b47295	334	idx = idx+1;
nixnax	216:e3c5a5b47295	335	if (idx > RXBUFLEN) idx=0;
nixnax	142:54d1543e23e5	336	if (idx == end) break;
nixnax	142:54d1543e23e5	337	}
nixnax	145:098b6ed2f7f2	338	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	339	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	340	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	341	determinePacketType();
nixnax	142:54d1543e23e5	342	} else {
nixnax	142:54d1543e23e5	343	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	344	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	345	char pbuf[50]; // local print buffer
nixnax	210:a2a651249a9a	346
nixnax	142:54d1543e23e5	347	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	210:a2a651249a9a	348
nixnax	142:54d1543e23e5	349	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	350	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	351	#endif
nixnax	142:54d1543e23e5	352	}
nixnax	142:54d1543e23e5	353	}
nixnax	142:54d1543e23e5	354
nixnax	142:54d1543e23e5	355	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	356	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	357	{
nixnax	210:a2a651249a9a	358
nixnax	142:54d1543e23e5	359	pc.putc(ch);
nixnax	210:a2a651249a9a	360
nixnax	142:54d1543e23e5	361	}
nixnax	142:54d1543e23e5	362
nixnax	142:54d1543e23e5	363	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	364	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	365	{
nixnax	142:54d1543e23e5	366	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	367	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	368	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	369	} else {
nixnax	142:54d1543e23e5	370	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	371	}
nixnax	142:54d1543e23e5	372	}
nixnax	142:54d1543e23e5	373
nixnax	142:54d1543e23e5	374	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	375	void sendPppFrame()
nixnax	143:c5019f856a56	376	{
nixnax	172:449dd7a28955	377	ppp.responseCounter++; // count the number of ppp frames we send
nixnax	145:098b6ed2f7f2	378	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	379	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	380	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	381	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	382	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	383	wait_us(86); // wait one character time
nixnax	210:a2a651249a9a	384
nixnax	142:54d1543e23e5	385	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	386	}
nixnax	142:54d1543e23e5	387	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	388	}
nixnax	142:54d1543e23e5	389
nixnax	143:c5019f856a56	390	/// 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	391	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	392	{
nixnax	143:c5019f856a56	393	int result=0;
nixnax	143:c5019f856a56	394	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	395	return result;
nixnax	143:c5019f856a56	396	}
nixnax	143:c5019f856a56	397
nixnax	177:dab9e685af53	398	/// convert 4-byte ip address to 32-bit
nixnax	179:ba2b2ddd0da5	399	unsigned int ip( int a, int b, int c, int d)
nixnax	179:ba2b2ddd0da5	400	{
nixnax	177:dab9e685af53	401	return a<<24 \| b<<16 \| c<<8 \| d;
nixnax	177:dab9e685af53	402	}
nixnax	177:dab9e685af53	403
nixnax	142:54d1543e23e5	404	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	405	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	406	{
nixnax	142:54d1543e23e5	407	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	173:6774a0c851c4	408	if(ppp.ipcp->request[0]==3) {
nixnax	143:c5019f856a56	409	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	173:6774a0c851c4	410	debugPrintf("Host IP = %d.%d.%d.%d (%08x)\n", ppp.ipcp->request[2],ppp.ipcp->request[3],ppp.ipcp->request[4],ppp.ipcp->request[5],ppp.hostIP);
nixnax	143:c5019f856a56	411	}
nixnax	143:c5019f856a56	412
nixnax	167:ff8a2d8beeb1	413	ppp.ipcp->code=2; // change code to ack
nixnax	144:01d98cf7738e	414	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	415
nixnax	142:54d1543e23e5	416	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	167:ff8a2d8beeb1	417	ppp.ipcp->code=1; // change code to request
nixnax	167:ff8a2d8beeb1	418	ppp.ipcp->lengthR = __REV16( 4 ); // 4 is minimum length - no options in this request
nixnax	167:ff8a2d8beeb1	419	ppp.pkt.len=4+4+2; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	420	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	421	}
nixnax	142:54d1543e23e5	422
nixnax	142:54d1543e23e5	423	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	424	void ipcpAckHandler()
nixnax	142:54d1543e23e5	425	{
nixnax	142:54d1543e23e5	426	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	427	}
nixnax	142:54d1543e23e5	428
nixnax	143:c5019f856a56	429	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	430	/// 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	431	void ipcpNackHandler()
nixnax	142:54d1543e23e5	432	{
nixnax	146:a45f49a2b29c	433	debugPrintf("Their IPCP Nack\n");
nixnax	173:6774a0c851c4	434	if (ppp.ipcp->request[0]==3) { // check if the NACK contains an IP address parameter
nixnax	167:ff8a2d8beeb1	435	ppp.ipcp->code=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	436	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	437	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	438	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	439	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	440	}
nixnax	142:54d1543e23e5	441	}
nixnax	142:54d1543e23e5	442
nixnax	142:54d1543e23e5	443	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	444	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	445	{
nixnax	142:54d1543e23e5	446	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	447	}
nixnax	142:54d1543e23e5	448
nixnax	142:54d1543e23e5	449	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	450	void IPCPframe()
nixnax	142:54d1543e23e5	451	{
nixnax	167:ff8a2d8beeb1	452	int action = ppp.ipcp->code; // packet type is here
nixnax	167:ff8a2d8beeb1	453	switch (action) {
nixnax	142:54d1543e23e5	454	case 1:
nixnax	142:54d1543e23e5	455	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	456	break;
nixnax	142:54d1543e23e5	457	case 2:
nixnax	142:54d1543e23e5	458	ipcpAckHandler();
nixnax	142:54d1543e23e5	459	break;
nixnax	142:54d1543e23e5	460	case 3:
nixnax	142:54d1543e23e5	461	ipcpNackHandler();
nixnax	142:54d1543e23e5	462	break;
nixnax	142:54d1543e23e5	463	default:
nixnax	142:54d1543e23e5	464	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	465	}
nixnax	142:54d1543e23e5	466	}
nixnax	142:54d1543e23e5	467
nixnax	142:54d1543e23e5	468	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	161:d59f778bc8ab	469	unsigned int dataCheckSum(char * ptr, int len, int restart)
nixnax	142:54d1543e23e5	470	{
nixnax	159:4d1bf96a59cd	471	unsigned int i,hi,lo;
nixnax	142:54d1543e23e5	472	unsigned char placeHolder;
nixnax	161:d59f778bc8ab	473	if (restart) ppp.sum=0;
nixnax	142:54d1543e23e5	474	if (len&1) {
nixnax	142:54d1543e23e5	475	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	476	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	477	}
nixnax	142:54d1543e23e5	478	i=0;
nixnax	142:54d1543e23e5	479	while ( i<len ) {
nixnax	210:a2a651249a9a	480
nixnax	142:54d1543e23e5	481	hi = ptr[i++];
nixnax	142:54d1543e23e5	482	lo = ptr[i++];
nixnax	159:4d1bf96a59cd	483	ppp.sum = ppp.sum + ((hi<<8)\|lo);
nixnax	142:54d1543e23e5	484	}
nixnax	142:54d1543e23e5	485	if (len&1) {
nixnax	142:54d1543e23e5	486	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	487	}
nixnax	159:4d1bf96a59cd	488	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax	159:4d1bf96a59cd	489	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax	159:4d1bf96a59cd	490	return ~ppp.sum;
nixnax	142:54d1543e23e5	491	}
nixnax	142:54d1543e23e5	492
nixnax	142:54d1543e23e5	493	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	494	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	495	{
nixnax	161:d59f778bc8ab	496	ppp.ip->checksumR=0; // zero the checsum in the IP header
nixnax	161:d59f778bc8ab	497	int len = 4 * ppp.ip->headerLength; // length of IP header in bytes
nixnax	161:d59f778bc8ab	498	unsigned int sum = dataCheckSum(ppp.ipStart,len,1);
nixnax	161:d59f778bc8ab	499	ppp.ip->checksumR = __REV16( sum ); // insert fresh checksum
nixnax	146:a45f49a2b29c	500	}
nixnax	146:a45f49a2b29c	501
nixnax	147:0f40005cbc5f	502	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	503	void swapIpAddresses()
nixnax	147:0f40005cbc5f	504	{
nixnax	162:594729c0e5c1	505	unsigned int tempHold;
nixnax	162:594729c0e5c1	506	tempHold = ppp.ip->srcAdrR; // tempHold <- source IP
nixnax	162:594729c0e5c1	507	ppp.ip->srcAdrR = ppp.ip->dstAdrR; // source <- dest
nixnax	162:594729c0e5c1	508	ppp.ip->dstAdrR = tempHold; // dest <- tempHold*/
nixnax	147:0f40005cbc5f	509	}
nixnax	147:0f40005cbc5f	510
nixnax	149:969d98f6fb88	511	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	512	void swapIpPorts()
nixnax	149:969d98f6fb88	513	{
nixnax	173:6774a0c851c4	514	int headerSizeIP = 4 * (ppp.ip->headerLength); // calculate size of IP header
nixnax	173:6774a0c851c4	515	char * ipSrcPort = ppp.ipStart + headerSizeIP + 0; // ip source port location
nixnax	173:6774a0c851c4	516	char * ipDstPort = ppp.ipStart + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	517	char tempHold[2];
nixnax	149:969d98f6fb88	518	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	519	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	520	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	521	}
nixnax	149:969d98f6fb88	522
nixnax	170:3d3b2126181c	523	/// Build the "pseudo header" required for UDP and TCP, then calculate its checksum
nixnax	170:3d3b2126181c	524	void checkSumPseudoHeader( unsigned int packetLength )
nixnax	170:3d3b2126181c	525	{
nixnax	170:3d3b2126181c	526	// this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax	170:3d3b2126181c	527	pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax	170:3d3b2126181c	528	pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax	170:3d3b2126181c	529	pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax	170:3d3b2126181c	530	pseudoHeader.zero = 0; // zero byte
nixnax	170:3d3b2126181c	531	pseudoHeader.protocol = ppp.ip->protocol; // protocol number (udp or tcp)
nixnax	170:3d3b2126181c	532	pseudoHeader.lengthR = __REV16( packetLength ); // size of tcp or udp packet
nixnax	170:3d3b2126181c	533	dataCheckSum(pseudoHeader.start, 12, 1); // calculate this header's checksum
nixnax	170:3d3b2126181c	534	}
nixnax	170:3d3b2126181c	535
nixnax	171:46b36d4edd1d	536	/// initialize an IP packet to send
nixnax	171:46b36d4edd1d	537	void initIP (unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, unsigned int protocol)
nixnax	171:46b36d4edd1d	538	{
nixnax	171:46b36d4edd1d	539	ppp.ppp->address = 0xff;
nixnax	171:46b36d4edd1d	540	ppp.ppp->control = 3;
nixnax	171:46b36d4edd1d	541	ppp.ppp->protocolR = __REV16( 0x0021 );
nixnax	171:46b36d4edd1d	542	ppp.ip->version = 4;
nixnax	171:46b36d4edd1d	543	ppp.ip->headerLength = 5; // 5 words = 20 bytes
nixnax	171:46b36d4edd1d	544	ppp.ip->identR = __REV16(ppp.ipData.ident++); // insert our ident
nixnax	171:46b36d4edd1d	545	ppp.ip->dontFragment=1;
nixnax	171:46b36d4edd1d	546	ppp.ip->ttl=128;
nixnax	171:46b36d4edd1d	547	ppp.ip->protocol = protocol; // udp
nixnax	171:46b36d4edd1d	548	ppp.ip->srcAdrR = __REV(srcIp);
nixnax	171:46b36d4edd1d	549	ppp.ip->dstAdrR = __REV(dstIp);
nixnax	171:46b36d4edd1d	550	ppp.udpStart = ppp.ipStart + 20; // calculate start of udp header
nixnax	171:46b36d4edd1d	551	ppp.udp->srcPortR = __REV16(srcPort); // source port
nixnax	171:46b36d4edd1d	552	ppp.udp->dstPortR = __REV16(dstPort); // dest port
nixnax	171:46b36d4edd1d	553	}
nixnax	171:46b36d4edd1d	554
nixnax	171:46b36d4edd1d	555
nixnax	171:46b36d4edd1d	556	/// Build a UDP packet from scratch
nixnax	171:46b36d4edd1d	557	void sendUdp(unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, char * message,int msgLen)
nixnax	171:46b36d4edd1d	558	{
nixnax	171:46b36d4edd1d	559	struct {
nixnax	171:46b36d4edd1d	560	unsigned int ipAll; // length of entire ip packet
nixnax	171:46b36d4edd1d	561	unsigned int ipHeader; // length of ip header
nixnax	171:46b36d4edd1d	562	unsigned int udpAll; // length of entire udp packet
nixnax	171:46b36d4edd1d	563	unsigned int udpData; // length of udp data segment
nixnax	171:46b36d4edd1d	564	} len;
nixnax	171:46b36d4edd1d	565	len.ipHeader = 20; // ip header length
nixnax	171:46b36d4edd1d	566	len.udpData = msgLen; // udp data size
nixnax	171:46b36d4edd1d	567	len.udpAll = len.udpData+8; // update local udp packet length
nixnax	171:46b36d4edd1d	568	len.ipAll = len.ipHeader + len.udpAll; // update IP Length
nixnax	171:46b36d4edd1d	569	initIP(srcIp, dstIp, srcPort, dstPort, 17); // init a UDP packet
nixnax	171:46b36d4edd1d	570	ppp.ip->lengthR = __REV16(len.ipAll); // update IP length in buffer
nixnax	171:46b36d4edd1d	571	ppp.udpStart = ppp.ipStart + len.ipHeader; // calculate start of udp header
nixnax	171:46b36d4edd1d	572	memcpy( ppp.udp->data, message, len.udpData ); // copy the message to the buffer
nixnax	171:46b36d4edd1d	573	ppp.udp->lengthR = __REV16(len.udpAll); // update UDP length in buffer
nixnax	171:46b36d4edd1d	574	ppp.pkt.len = len.ipAll+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	575	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	576	checkSumPseudoHeader( len.udpAll ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	577	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	578	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,len.udpAll, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	579	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	580	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	581	}
nixnax	171:46b36d4edd1d	582
nixnax	146:a45f49a2b29c	583	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	584	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	585	void UDPpacket()
nixnax	146:a45f49a2b29c	586	{
nixnax	163:d1b4328e9f08	587	struct {
nixnax	163:d1b4328e9f08	588	unsigned int all; // length of entire ip packet
nixnax	163:d1b4328e9f08	589	unsigned int header; // length of ip header
nixnax	163:d1b4328e9f08	590	} ipLength;
nixnax	163:d1b4328e9f08	591
nixnax	163:d1b4328e9f08	592	struct {
nixnax	165:c47826d07e0d	593	unsigned int all; // length of entire udp packet
nixnax	163:d1b4328e9f08	594	unsigned int data; // length of udp data segment
nixnax	163:d1b4328e9f08	595	} udpLength;
nixnax	163:d1b4328e9f08	596
nixnax	163:d1b4328e9f08	597	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	163:d1b4328e9f08	598	ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	171:46b36d4edd1d	599	udpLength.all = __REV16( ppp.udp->lengthR ); // size of udp packet
nixnax	163:d1b4328e9f08	600	udpLength.data = udpLength.all - 8; // size of udp data
nixnax	147:0f40005cbc5f	601
nixnax	146:a45f49a2b29c	602	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	171:46b36d4edd1d	603	char * srcIP = ppp.ip->srcAdrPtr; // IP source
nixnax	171:46b36d4edd1d	604	char * dstIP = ppp.ip->dstAdrPtr; //IP destination
nixnax	163:d1b4328e9f08	605
nixnax	171:46b36d4edd1d	606	unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); // integer of UDP source port
nixnax	171:46b36d4edd1d	607	unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); // integer of UDP dest port
nixnax	163:d1b4328e9f08	608
nixnax	163:d1b4328e9f08	609	if(v0) {
nixnax	163:d1b4328e9f08	610	debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
nixnax	163:d1b4328e9f08	611	debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
nixnax	163:d1b4328e9f08	612	debugPrintf("Len %03d", udpLength);
nixnax	163:d1b4328e9f08	613	}
nixnax	146:a45f49a2b29c	614	if (v1) {
nixnax	163:d1b4328e9f08	615	int printSize = udpLength.data;
nixnax	146:a45f49a2b29c	616	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	617	for (int i=0; i<printSize; i++) {
nixnax	163:d1b4328e9f08	618	char ch = ppp.udp->data[i];
nixnax	146:a45f49a2b29c	619	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	620	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	621	} else {
nixnax	146:a45f49a2b29c	622	debugPrintf("_");
nixnax	146:a45f49a2b29c	623	}
nixnax	146:a45f49a2b29c	624	}
nixnax	146:a45f49a2b29c	625	}
nixnax	146:a45f49a2b29c	626	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	627	#endif
nixnax	163:d1b4328e9f08	628	int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
nixnax	163:d1b4328e9f08	629	int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	630	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	146:a45f49a2b29c	631	if (echoFound) {
nixnax	171:46b36d4edd1d	632	swapIpAddresses(); // swap IP source and destination
nixnax	171:46b36d4edd1d	633	swapIpPorts(); // swap IP source and destination ports
nixnax	163:d1b4328e9f08	634	memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	170:3d3b2126181c	635	int n=0;
nixnax	170:3d3b2126181c	636	n=n+sprintf(n+ppp.udp->data+udpLength.data, "} UDP Server: PPP-Blinky\n"); // an appendix
nixnax	168:c77eb908042a	637	udpLength.data = udpLength.data + n; // update udp data size with the size of the appendix
nixnax	171:46b36d4edd1d	638	// we may have changed data length, update all the lengths
nixnax	171:46b36d4edd1d	639	udpLength.all = udpLength.data+8; // update local udp packet length
nixnax	171:46b36d4edd1d	640	ipLength.all = ipLength.header + udpLength.all; // update IP Length
nixnax	171:46b36d4edd1d	641	ppp.ip->lengthR = __REV16(ipLength.all); // update IP length in buffer
nixnax	171:46b36d4edd1d	642	ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
nixnax	171:46b36d4edd1d	643	ppp.pkt.len = ipLength.all+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	644	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	645	checkSumPseudoHeader( udpLength.all ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	646	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	647	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,udpLength.all, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	648	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	649	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	650	} else if ( testFound ) {
nixnax	171:46b36d4edd1d	651	unsigned int sI = __REV( ppp.ip->srcAdrR );
nixnax	171:46b36d4edd1d	652	unsigned int dI = __REV( ppp.ip->dstAdrR );
nixnax	171:46b36d4edd1d	653	unsigned int sp = __REV16( ppp.udp->srcPortR );
nixnax	171:46b36d4edd1d	654	unsigned int dp = __REV16( ppp.udp->dstPortR );
nixnax	172:449dd7a28955	655	int n=sprintf(ppp.pkt.buf+200,"Response Count %d\n", ppp.responseCounter);
nixnax	171:46b36d4edd1d	656	sendUdp(dI,sI,dp,sp,ppp.pkt.buf+200,n); // build a udp packet from the ground up
nixnax	146:a45f49a2b29c	657	}
nixnax	146:a45f49a2b29c	658	}
nixnax	142:54d1543e23e5	659	}
nixnax	142:54d1543e23e5	660
nixnax	174:e5a3f16421a5	661	/// UDP demo that sends a udp packet containing a character received from the second debug serial port.
nixnax	174:e5a3f16421a5	662	/// Sends a 48 byte IP/UDP header for every 1 byte of data so line-mode would probably be better.
nixnax	178:3f17aa0ce5ce	663	/// If you want ip packets from ppp blinky to be routed to other networks, ensure you have ip routing enabled.
nixnax	178:3f17aa0ce5ce	664	/// See http://www.wikihow.com/Enable-IP-Routing.
nixnax	179:ba2b2ddd0da5	665	/// Also ensure that the firewall on the receiving machine has the receiving UDP port (12345 in this example) enabled.
nixnax	179:ba2b2ddd0da5	666	/// The netcat UDP receive command on the remote host would be: nc -ul 12345
nixnax	174:e5a3f16421a5	667	void sendUdpData()
nixnax	174:e5a3f16421a5	668	{
nixnax	174:e5a3f16421a5	669	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	179:ba2b2ddd0da5	670	if (ppp.online) {
nixnax	179:ba2b2ddd0da5	671	if (xx.readable()) {
nixnax	179:ba2b2ddd0da5	672	char inchar = xx.getc();
nixnax	179:ba2b2ddd0da5	673	xx.putc( inchar ); // echo the received character on the debug serial port
nixnax	179:ba2b2ddd0da5	674	sendUdp(ip(172,10,10,2), ip(192,168,0,109), 1, 12345, &inchar, 1); // send a 1 byte UDP message to a remote machine at IP 192.168.0.109:12345
nixnax	179:ba2b2ddd0da5	675	}
nixnax	174:e5a3f16421a5	676	}
nixnax	174:e5a3f16421a5	677	#endif
nixnax	174:e5a3f16421a5	678	}
nixnax	174:e5a3f16421a5	679
nixnax	142:54d1543e23e5	680	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	681	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	682	{
nixnax	165:c47826d07e0d	683	struct {
nixnax	165:c47826d07e0d	684	unsigned int all; // length of entire ip packet
nixnax	165:c47826d07e0d	685	unsigned int header; // length of ip header
nixnax	165:c47826d07e0d	686	} ipLength;
nixnax	165:c47826d07e0d	687	struct {
nixnax	165:c47826d07e0d	688	unsigned int all; // length of entire udp packet
nixnax	165:c47826d07e0d	689	unsigned int data; // length of udp data segment
nixnax	165:c47826d07e0d	690	} icmpLength;
nixnax	165:c47826d07e0d	691	ipLength.all = __REV16( ppp.ip->lengthR ); // length of ip packet
nixnax	165:c47826d07e0d	692	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	165:c47826d07e0d	693	ppp.icmpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	165:c47826d07e0d	694	icmpLength.all = ipLength.all - ipLength.header; // length of icmp packet
nixnax	165:c47826d07e0d	695	icmpLength.data = icmpLength.all - 8; // length of icmp data
nixnax	142:54d1543e23e5	696	#define ICMP_TYPE_PING_REQUEST 8
nixnax	165:c47826d07e0d	697	if ( ppp.icmp->type == ICMP_TYPE_PING_REQUEST ) {
nixnax	165:c47826d07e0d	698	ppp.ip->ttl--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	699	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	167:ff8a2d8beeb1	700	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	701	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	165:c47826d07e0d	702	int icmpIdent = __REV16( ppp.ip->identR ); // byte reversed - big endian
nixnax	165:c47826d07e0d	703	int icmpSequence = __REV16( ppp.icmp->sequenceR ); // byte reversed - big endian
nixnax	142:54d1543e23e5	704	if(1) {
nixnax	142:54d1543e23e5	705	char pbuf[50];
nixnax	210:a2a651249a9a	706
nixnax	142:54d1543e23e5	707	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	708	putsWhileCheckingInput( pbuf );
nixnax	210:a2a651249a9a	709
nixnax	142:54d1543e23e5	710	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	210:a2a651249a9a	711
nixnax	142:54d1543e23e5	712	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	713	}
nixnax	142:54d1543e23e5	714	#endif
nixnax	147:0f40005cbc5f	715	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	716	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	717	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	165:c47826d07e0d	718	ppp.icmp->type = ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	165:c47826d07e0d	719	ppp.icmp->checkSumR = 0; // zero the checksum for recalculation
nixnax	165:c47826d07e0d	720	unsigned int sum = dataCheckSum(ppp.icmpStart, icmpLength.all, 1); // icmp checksum
nixnax	165:c47826d07e0d	721	ppp.icmp->checkSumR = __REV16( sum ); // save big-endian icmp checksum
nixnax	142:54d1543e23e5	722
nixnax	165:c47826d07e0d	723	int printSize = icmpLength.data; // exclude size of icmp header
nixnax	142:54d1543e23e5	724	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	725	if (0) {
nixnax	142:54d1543e23e5	726	for (int i=0; i<printSize; i++) {
nixnax	165:c47826d07e0d	727	char ch = ppp.icmp->data[i];
nixnax	142:54d1543e23e5	728	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	729	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	730	} else {
nixnax	142:54d1543e23e5	731	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	732	}
nixnax	142:54d1543e23e5	733	}
nixnax	142:54d1543e23e5	734	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	735	}
nixnax	144:01d98cf7738e	736	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	737	} else {
nixnax	142:54d1543e23e5	738	if (v0) {
nixnax	165:c47826d07e0d	739	debugPrintf("ICMP type=%x \n", ppp.icmp->type);
nixnax	142:54d1543e23e5	740	}
nixnax	142:54d1543e23e5	741	}
nixnax	142:54d1543e23e5	742	}
nixnax	142:54d1543e23e5	743
nixnax	142:54d1543e23e5	744	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	745	void IGMPpacket()
nixnax	142:54d1543e23e5	746	{
nixnax	142:54d1543e23e5	747	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	748	}
nixnax	142:54d1543e23e5	749
nixnax	142:54d1543e23e5	750	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	751	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	752	{
nixnax	142:54d1543e23e5	753	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	210:a2a651249a9a	754
nixnax	155:9c6a1d249e26	755	int IPv4Id = __REV16(ppp.ip->identR);
nixnax	152:025c73b6c0a9	756	char pbuf[80]; // local print buffer
nixnax	142:54d1543e23e5	757	int n=0;
nixnax	142:54d1543e23e5	758	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	759	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	760	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	761	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	167:ff8a2d8beeb1	762	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	763	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	142:54d1543e23e5	764	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	765	#endif
nixnax	142:54d1543e23e5	766	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	767	#ifndef TCP_HEADER_DUMP_YES
nixnax	160:bd701ad564cb	768	putsWhileCheckingInput('\x1b[30m\n'); // if there's no TCP header dump we terminate the line with \n and VT100 code for black
nixnax	142:54d1543e23e5	769	#endif
nixnax	142:54d1543e23e5	770	#endif
nixnax	142:54d1543e23e5	771	}
nixnax	142:54d1543e23e5	772
nixnax	142:54d1543e23e5	773	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	774	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	775	{
nixnax	142:54d1543e23e5	776	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	155:9c6a1d249e26	777	char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	778	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	779	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	155:9c6a1d249e26	780	memset(flagString,'.', 8); // fill string with "........"
nixnax	156:163c23249731	781	if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax	156:163c23249731	782	if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax	156:163c23249731	783	if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax	156:163c23249731	784	if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax	156:163c23249731	785	if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax	156:163c23249731	786	if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax	156:163c23249731	787	if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax	156:163c23249731	788	if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax	155:9c6a1d249e26	789	flagString[8]=0; // null terminate string
nixnax	142:54d1543e23e5	790	#else
nixnax	156:163c23249731	791	if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax	156:163c23249731	792	if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax	156:163c23249731	793	if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax	156:163c23249731	794	if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax	156:163c23249731	795	if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax	155:9c6a1d249e26	796	flagString[1]=0; // null terminate string
nixnax	142:54d1543e23e5	797	#endif
nixnax	155:9c6a1d249e26	798	putsWhileCheckingInput( flagString );
nixnax	142:54d1543e23e5	799	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	800	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	801	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	160:bd701ad564cb	802	#else
nixnax	160:bd701ad564cb	803	putsWhileCheckingInput("\x1b[30m"); // write a black color after every packet
nixnax	142:54d1543e23e5	804	#endif
nixnax	156:163c23249731	805	if( outGoing && ppp.tcp->flag.fin ) { // ACK/FIN - if this is an outgoing FIN it's the end of a tcp conversation
nixnax	160:bd701ad564cb	806	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end (except for final ack) of an HTTP conversation
nixnax	142:54d1543e23e5	807	}
nixnax	142:54d1543e23e5	808	#endif
nixnax	142:54d1543e23e5	809	}
nixnax	142:54d1543e23e5	810
nixnax	143:c5019f856a56	811	/// Encode a buffer in base-64
nixnax	184:4133f557d4d4	812	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	813	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	814	{
nixnax	142:54d1543e23e5	815	int i,j,a,b,c;
nixnax	142:54d1543e23e5	816	i=0;
nixnax	142:54d1543e23e5	817	j=0;
nixnax	142:54d1543e23e5	818	while(1) {
nixnax	142:54d1543e23e5	819	if (i<len) {
nixnax	142:54d1543e23e5	820	a = in[i++];
nixnax	142:54d1543e23e5	821	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	822	} else break;
nixnax	142:54d1543e23e5	823	if (i<len) {
nixnax	142:54d1543e23e5	824	b = in[i++];
nixnax	142:54d1543e23e5	825	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	826	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	827	} else out[j++] = '=';
nixnax	142:54d1543e23e5	828	if (i<len) {
nixnax	142:54d1543e23e5	829	c = in[i++];
nixnax	142:54d1543e23e5	830	j--;
nixnax	142:54d1543e23e5	831	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	832	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	833	} else out[j++] = '=';
nixnax	142:54d1543e23e5	834	}
nixnax	142:54d1543e23e5	835	out[j]=0;
nixnax	142:54d1543e23e5	836	}
nixnax	142:54d1543e23e5	837
nixnax	160:bd701ad564cb	838	/// Handle a request for an http websocket.
nixnax	160:bd701ad564cb	839	/// 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	840	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	841	{
nixnax	142:54d1543e23e5	842	int n=0; // byte counter
nixnax	184:4133f557d4d4	843	char * key = strstr(dataStart, "Sec-WebSocket-Key:"); // search for the key in the payload
nixnax	142:54d1543e23e5	844	if (key != NULL) {
nixnax	184:4133f557d4d4	845	key = key + 18; // skip over the key ident string "Sec-WebSocket-Key:"
nixnax	142:54d1543e23e5	846	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	184:4133f557d4d4	847	while ( strchr(lut, *key) == NULL) key++; // skip non-valid base-64 characters (whitespace)
nixnax	184:4133f557d4d4	848	char challenge [80];
nixnax	184:4133f557d4d4	849	int i=0;
nixnax	184:4133f557d4d4	850	char * copyTo = challenge;
nixnax	184:4133f557d4d4	851	while (strchr(lut, *key) != NULL) { // copy while we see valid base-64 characters
nixnax	184:4133f557d4d4	852	if (i++ >40) break; // prevent buffer overflow
nixnax	184:4133f557d4d4	853	copyTo++ = key++; // copy next valid base-64 character
nixnax	184:4133f557d4d4	854	}
nixnax	184:4133f557d4d4	855	strcpy(copyTo,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"); // append websocket gui code
nixnax	184:4133f557d4d4	856	if (0) debugPrintf("Challenge is %s\n", challenge); // the string we hash for the challenge
nixnax	142:54d1543e23e5	857	char shaOutput [20]; // sha1 output
nixnax	184:4133f557d4d4	858	sha1( shaOutput, challenge, strlen(challenge)); // hash the challenge
nixnax	142:54d1543e23e5	859	char encOut[50];
nixnax	184:4133f557d4d4	860	enc64( shaOutput, encOut, 20); // base-64 encode
nixnax	142:54d1543e23e5	861	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	862	char * version = challenge;
nixnax	184:4133f557d4d4	863	strncpy(version, versionstring,70); // copy their version string
nixnax	142:54d1543e23e5	864	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	865	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	866	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	867	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	868	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	869	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	870	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	871	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	872	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	873	}
nixnax	142:54d1543e23e5	874	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	875	}
nixnax	142:54d1543e23e5	876
nixnax	142:54d1543e23e5	877	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	878	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	879	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	880	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	881	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	882
nixnax	142:54d1543e23e5	883	/// respond to an HTTP request
nixnax	185:4cd8f91e9d49	884	int httpResponse(char * dataStart, int * flags)
nixnax	142:54d1543e23e5	885	{
nixnax	142:54d1543e23e5	886	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	887	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	160:bd701ad564cb	888	if (n>0) return n; // if n>0 we already have a response, so return
nixnax	142:54d1543e23e5	889
nixnax	142:54d1543e23e5	890	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	891	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	892	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	185:4cd8f91e9d49	893	*flags = TCP_FLAG_ACK \| TCP_FLAG_FIN; // the default case is that we close the connection
nixnax	142:54d1543e23e5	894
nixnax	142:54d1543e23e5	895	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	896	httpGetx = strncmp(dataStart, "GET /x", 6); // found a GET to /x which we will treat special (anything starting with /x, e.g. /x, /xyz, /xABC?pqr=123
nixnax	142:54d1543e23e5	897	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	898	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	899	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	210:a2a651249a9a	900	if( (httpGetRoot==0) \|\| (httpGetx==0) \|\| (httpGet5 == 'w') ) {
nixnax	142:54d1543e23e5	901	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	902	} else {
nixnax	142:54d1543e23e5	903	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	904	}
nixnax	142:54d1543e23e5	905	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	906	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	907	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	908	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	217:86498f9ab967	909	#define SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	910	#ifdef SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	911	// if this is enabled then the maximum value of the serial port receive buffer will show up in the http headers of your browser - nice for debugging
nixnax	210:a2a651249a9a	912	n=n+sprintf(n+dataStart,"Maxbuflevel: %d\r\n", ppp.rx.maxbuflevel);
nixnax	210:a2a651249a9a	913	#endif
nixnax	142:54d1543e23e5	914	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	915	nHeader=n; // size of HTTP header
nixnax	210:a2a651249a9a	916
nixnax	142:54d1543e23e5	917	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	918	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	919	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	920	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	185:4cd8f91e9d49	921
nixnax	210:a2a651249a9a	922	} else if ( httpGet5 == 'w' ) { // "w" is a special page for websocket demo
nixnax	142:54d1543e23e5	923	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	924	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	185:4cd8f91e9d49	925	*flags = TCP_FLAG_ACK \| TCP_FLAG_PSH; // for a websocket page we do NOT close the connection
nixnax	142:54d1543e23e5	926	} else {
nixnax	142:54d1543e23e5	927	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	928	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	929	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	930	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	931	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	932	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	933	#else
nixnax	142:54d1543e23e5	934	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	167:ff8a2d8beeb1	935	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	936	}
nixnax	142:54d1543e23e5	937	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	938	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	939	#endif
nixnax	142:54d1543e23e5	940	} else {
nixnax	142:54d1543e23e5	941	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	942	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	943	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	944	}
nixnax	142:54d1543e23e5	945	}
nixnax	142:54d1543e23e5	946	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	947	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	948	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	949	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	950	return n; // total byte size of our response
nixnax	142:54d1543e23e5	951	}
nixnax	142:54d1543e23e5	952
nixnax	160:bd701ad564cb	953	/// Handle TCP data that is not an HTTP GET.
nixnax	160:bd701ad564cb	954	/// This is handy when for example you want to use netcat (nc.exe) to talk to PPP-Blinky.
nixnax	160:bd701ad564cb	955	/// This could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	956	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	957	{
nixnax	142:54d1543e23e5	958	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	959	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	160:bd701ad564cb	960	char mask [4];
nixnax	160:bd701ad564cb	961	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	160:bd701ad564cb	962	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	160:bd701ad564cb	963	if((dataStart[1]&0x80)==0x80) // test if the mask bit is set, which means all data is xor'ed with the mask
nixnax	160:bd701ad564cb	964	for (int i=0; i<websocketMessageSize; i++) dataStart[i+6]^= mask[i%4]; // unmask each byte with one of the mask bytes
nixnax	160:bd701ad564cb	965	dataStart[1] = len-2; // add four extra bytes to the message length because we don't use mask bytes for the send
nixnax	160:bd701ad564cb	966	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	160:bd701ad564cb	967	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	968	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	969	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	970	dataStart[1]=0; // we don't have mask bytes on
nixnax	160:bd701ad564cb	971	} else {
nixnax	184:4133f557d4d4	972	if ( len > 1 ) { // we assume a length of 1 is a keep-alive or push packet
nixnax	184:4133f557d4d4	973	if (v1) putsWhileCheckingInput("TCP data received\n"); // all other tcp push packets
nixnax	184:4133f557d4d4	974	}
nixnax	163:d1b4328e9f08	975	}
nixnax	142:54d1543e23e5	976	return n; // total byte size of our response
nixnax	142:54d1543e23e5	977	}
nixnax	142:54d1543e23e5	978
nixnax	173:6774a0c851c4	979	/// dump the TCP data to the debug serial port
nixnax	173:6774a0c851c4	980	void dumpDataTCP(int outGoing)
nixnax	173:6774a0c851c4	981	{
nixnax	173:6774a0c851c4	982	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	173:6774a0c851c4	983	if (v2) {
nixnax	173:6774a0c851c4	984	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	173:6774a0c851c4	985	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	986	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax	173:6774a0c851c4	987	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	988	ppp.tcpData = ppp.tcpStart + headerSizeTcp; // start of tcp data
nixnax	173:6774a0c851c4	989	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	173:6774a0c851c4	990	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	173:6774a0c851c4	991	char pbuf[80]; // local print buffer
nixnax	173:6774a0c851c4	992	int n=0;
nixnax	210:a2a651249a9a	993
nixnax	173:6774a0c851c4	994	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	210:a2a651249a9a	995
nixnax	173:6774a0c851c4	996	n=n+sprintf(pbuf+n, "IP:%d ipHeader:%d tcpHeader:%d tcpData:%d\n", packetLengthIp, headerSizeIp, headerSizeTcp, tcpDataSize); // 1 for more verbose
nixnax	184:4133f557d4d4	997	if (n>70) putsWhileCheckingInput("n>pbuf overflow in dumpDataTCP()\n");
nixnax	210:a2a651249a9a	998
nixnax	173:6774a0c851c4	999	putsWhileCheckingInput( pbuf );
nixnax	173:6774a0c851c4	1000	if (tcpDataSize > 0) {
nixnax	173:6774a0c851c4	1001	ppp.tcpData[tcpDataSize]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	173:6774a0c851c4	1002	putsWhileCheckingInput( ppp.tcpData ); // print the tcp payload data
nixnax	173:6774a0c851c4	1003	putsWhileCheckingInput("\n");
nixnax	173:6774a0c851c4	1004	}
nixnax	173:6774a0c851c4	1005	putsWhileCheckingInput( "\x1b[30m" ); // VT100 color code, print black
nixnax	173:6774a0c851c4	1006	}
nixnax	173:6774a0c851c4	1007	#endif
nixnax	173:6774a0c851c4	1008	}
nixnax	173:6774a0c851c4	1009
nixnax	142:54d1543e23e5	1010	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1011	/// 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	1012	void tcpHandler()
nixnax	142:54d1543e23e5	1013	{
nixnax	154:18b2bd92f557	1014	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	154:18b2bd92f557	1015	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	1016	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate TCP header start
nixnax	154:18b2bd92f557	1017	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	154:18b2bd92f557	1018	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	1019	char * tcpDataIn = ppp.tcpStart + headerSizeTcp; // start of data TCP data after TCP header
nixnax	154:18b2bd92f557	1020	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	154:18b2bd92f557	1021
nixnax	154:18b2bd92f557	1022	unsigned int seq_in = __REV(ppp.tcp->seqTcpR);
nixnax	154:18b2bd92f557	1023	unsigned int ack_in = __REV(ppp.tcp->ackTcpR);
nixnax	142:54d1543e23e5	1024	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	1025	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	1026
nixnax	142:54d1543e23e5	1027	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	173:6774a0c851c4	1028	headerSizeIp=20;
nixnax	173:6774a0c851c4	1029	ppp.ip->headerLength = headerSizeIp/4; // ip header is 20 bytes long
nixnax	173:6774a0c851c4	1030	ppp.ip->lengthR = __REV(40); // 20 ip header + 20 tcp header
nixnax	173:6774a0c851c4	1031	//tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	154:18b2bd92f557	1032	headerSizeTcp = 20; // shorten outgoing TCP header size 20 bytes
nixnax	173:6774a0c851c4	1033	ppp.tcpStart = ppp.ipStart + headerSizeIp; // recalc TCP header start
nixnax	154:18b2bd92f557	1034	ppp.tcp->offset = (headerSizeTcp/4);
nixnax	173:6774a0c851c4	1035	char * tcpDataOut = ppp.tcpStart + headerSizeTcp; // start of outgoing data
nixnax	142:54d1543e23e5	1036
nixnax	142:54d1543e23e5	1037	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	1038	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	160:bd701ad564cb	1039
nixnax	185:4cd8f91e9d49	1040	ppp.tcp->windowR = __REV16( 1200 ); // set tcp window size to 1200 bytes
nixnax	142:54d1543e23e5	1041
nixnax	142:54d1543e23e5	1042	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	1043
nixnax	156:163c23249731	1044	switch ( ppp.tcp->flag.All ) {
nixnax	142:54d1543e23e5	1045	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1046	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1047	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1048	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1049	break;
nixnax	184:4133f557d4d4	1050	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1051	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	184:4133f557d4d4	1052	if ( (ppp.tcp->flag.All == TCP_FLAG_ACK) && (tcpDataSize == 0)) return; // handle zero-size ack messages by ignoring them
nixnax	142:54d1543e23e5	1053	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	179:ba2b2ddd0da5	1054	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // we have data, set the PSH flag
nixnax	185:4cd8f91e9d49	1055	dataLen = httpResponse(tcpDataOut, &flagsOut); // send an http response
nixnax	142:54d1543e23e5	1056	} else {
nixnax	158:841592aed956	1057	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax	179:ba2b2ddd0da5	1058	if (dataLen > 0) flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // if we have any data set the PSH flag
nixnax	142:54d1543e23e5	1059	}
nixnax	142:54d1543e23e5	1060	break;
nixnax	142:54d1543e23e5	1061	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1062	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1063	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1064	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1065	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1066	break;
nixnax	142:54d1543e23e5	1067	default:
nixnax	179:ba2b2ddd0da5	1068	return; // ignore all other packets
nixnax	142:54d1543e23e5	1069	} // switch
nixnax	142:54d1543e23e5	1070
nixnax	142:54d1543e23e5	1071	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1072	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1073	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1074	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1075
nixnax	158:841592aed956	1076	ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	158:841592aed956	1077	ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	160:bd701ad564cb	1078
nixnax	156:163c23249731	1079	ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1080
nixnax	159:4d1bf96a59cd	1081	// recalculate all the header sizes
nixnax	154:18b2bd92f557	1082	tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax	154:18b2bd92f557	1083	int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax	159:4d1bf96a59cd	1084	ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax	142:54d1543e23e5	1085	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	1086
nixnax	142:54d1543e23e5	1087	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1088	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	170:3d3b2126181c	1089	checkSumPseudoHeader( tcpSize ); // get the TCP pseudo-header checksum
nixnax	159:4d1bf96a59cd	1090	ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	161:d59f778bc8ab	1091	unsigned int pseudoHeaderSum=dataCheckSum(ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax	159:4d1bf96a59cd	1092	ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	160:bd701ad564cb	1093
nixnax	170:3d3b2126181c	1094	dumpHeaderIP(1); // dump outgoing IP header before sending the frame
nixnax	170:3d3b2126181c	1095	dumpHeaderTCP(1); // dump outgoing TCP header before sending the frame
nixnax	173:6774a0c851c4	1096	dumpDataTCP(1); // dump outgoing TCP data before sending the frame
nixnax	182:f039ec218c9f	1097	if (0) wait_ms(45); // 45 ms delay before sending frame - a typical internet delay time
nixnax	144:01d98cf7738e	1098	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1099	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1100	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1101	}
nixnax	142:54d1543e23e5	1102
nixnax	142:54d1543e23e5	1103	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1104	void TCPpacket()
nixnax	142:54d1543e23e5	1105	{
nixnax	173:6774a0c851c4	1106	dumpHeaderIP(0); // dump incoming packet IP header
nixnax	173:6774a0c851c4	1107	dumpHeaderTCP(0); // dump incoming packet TCP header
nixnax	173:6774a0c851c4	1108	dumpDataTCP(0); // dump incoming packet data
nixnax	142:54d1543e23e5	1109	tcpHandler();
nixnax	142:54d1543e23e5	1110	}
nixnax	142:54d1543e23e5	1111
nixnax	142:54d1543e23e5	1112	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1113	void otherProtocol()
nixnax	142:54d1543e23e5	1114	{
nixnax	142:54d1543e23e5	1115	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1116	}
nixnax	142:54d1543e23e5	1117
nixnax	142:54d1543e23e5	1118	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1119	void IPframe()
nixnax	142:54d1543e23e5	1120	{
nixnax	167:ff8a2d8beeb1	1121	int protocol = ppp.ip->protocol;
nixnax	142:54d1543e23e5	1122	switch (protocol) {
nixnax	142:54d1543e23e5	1123	case 1:
nixnax	142:54d1543e23e5	1124	ICMPpacket();
nixnax	142:54d1543e23e5	1125	break;
nixnax	142:54d1543e23e5	1126	case 2:
nixnax	142:54d1543e23e5	1127	IGMPpacket();
nixnax	142:54d1543e23e5	1128	break;
nixnax	142:54d1543e23e5	1129	case 17:
nixnax	142:54d1543e23e5	1130	UDPpacket();
nixnax	142:54d1543e23e5	1131	break;
nixnax	142:54d1543e23e5	1132	case 6:
nixnax	142:54d1543e23e5	1133	TCPpacket();
nixnax	142:54d1543e23e5	1134	break;
nixnax	142:54d1543e23e5	1135	default:
nixnax	142:54d1543e23e5	1136	otherProtocol();
nixnax	142:54d1543e23e5	1137	}
nixnax	142:54d1543e23e5	1138	}
nixnax	142:54d1543e23e5	1139
nixnax	142:54d1543e23e5	1140	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1141	void LCPconfReq()
nixnax	142:54d1543e23e5	1142	{
nixnax	142:54d1543e23e5	1143	debugPrintf("LCP Config ");
nixnax	175:b4e6f8a6fe00	1144	if ( ppp.lcp->lengthR != __REV16(4) ) {
nixnax	175:b4e6f8a6fe00	1145	ppp.lcp->code=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1146	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1147	sendPppFrame();
nixnax	142:54d1543e23e5	1148	} else {
nixnax	175:b4e6f8a6fe00	1149	ppp.lcp->code=2; // ack zero conf
nixnax	142:54d1543e23e5	1150	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1151	sendPppFrame();
nixnax	142:54d1543e23e5	1152	debugPrintf("LCP Ask\n");
nixnax	175:b4e6f8a6fe00	1153	ppp.lcp->code=1; // request no options
nixnax	144:01d98cf7738e	1154	sendPppFrame();
nixnax	142:54d1543e23e5	1155	}
nixnax	142:54d1543e23e5	1156	}
nixnax	142:54d1543e23e5	1157
nixnax	142:54d1543e23e5	1158	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1159	void LCPconfAck()
nixnax	142:54d1543e23e5	1160	{
nixnax	142:54d1543e23e5	1161	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1162	}
nixnax	142:54d1543e23e5	1163
nixnax	143:c5019f856a56	1164	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1165	void LCPend()
nixnax	142:54d1543e23e5	1166	{
nixnax	175:b4e6f8a6fe00	1167	ppp.lcp->code=6; // end
nixnax	144:01d98cf7738e	1168	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1169	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1170	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1171	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1172	}
nixnax	142:54d1543e23e5	1173
nixnax	142:54d1543e23e5	1174	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1175	void LCPother()
nixnax	142:54d1543e23e5	1176	{
nixnax	142:54d1543e23e5	1177	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1178	dumpPPPFrame();
nixnax	142:54d1543e23e5	1179	}
nixnax	142:54d1543e23e5	1180
nixnax	142:54d1543e23e5	1181	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1182	void LCPframe()
nixnax	142:54d1543e23e5	1183	{
nixnax	175:b4e6f8a6fe00	1184	int code = ppp.lcp->code;
nixnax	142:54d1543e23e5	1185	switch (code) {
nixnax	142:54d1543e23e5	1186	case 1:
nixnax	142:54d1543e23e5	1187	LCPconfReq();
nixnax	142:54d1543e23e5	1188	break; // config request
nixnax	142:54d1543e23e5	1189	case 2:
nixnax	142:54d1543e23e5	1190	LCPconfAck();
nixnax	142:54d1543e23e5	1191	break; // config ack
nixnax	142:54d1543e23e5	1192	case 5:
nixnax	142:54d1543e23e5	1193	LCPend();
nixnax	142:54d1543e23e5	1194	break; // end connection
nixnax	142:54d1543e23e5	1195	default:
nixnax	142:54d1543e23e5	1196	LCPother();
nixnax	142:54d1543e23e5	1197	}
nixnax	142:54d1543e23e5	1198	}
nixnax	142:54d1543e23e5	1199
nixnax	142:54d1543e23e5	1200	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1201	void discardedFrame()
nixnax	142:54d1543e23e5	1202	{
nixnax	142:54d1543e23e5	1203	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	1204	}
nixnax	142:54d1543e23e5	1205
nixnax	142:54d1543e23e5	1206	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1207	void determinePacketType()
nixnax	142:54d1543e23e5	1208	{
nixnax	167:ff8a2d8beeb1	1209	if ( ppp.ppp->address != 0xff ) {
nixnax	167:ff8a2d8beeb1	1210	debugPrintf("Unexpected: PPP address != ff\n");
nixnax	142:54d1543e23e5	1211	return;
nixnax	142:54d1543e23e5	1212	}
nixnax	167:ff8a2d8beeb1	1213	if ( ppp.ppp->control != 3 ) {
nixnax	167:ff8a2d8beeb1	1214	debugPrintf("Unexpected: PPP control != 3\n");
nixnax	142:54d1543e23e5	1215	return;
nixnax	142:54d1543e23e5	1216	}
nixnax	167:ff8a2d8beeb1	1217	unsigned int protocol = __REV16( ppp.ppp->protocolR );
nixnax	167:ff8a2d8beeb1	1218	switch ( protocol ) {
nixnax	167:ff8a2d8beeb1	1219	case 0xc021:
nixnax	142:54d1543e23e5	1220	LCPframe();
nixnax	142:54d1543e23e5	1221	break; // link control
nixnax	167:ff8a2d8beeb1	1222	case 0x8021:
nixnax	142:54d1543e23e5	1223	IPCPframe();
nixnax	142:54d1543e23e5	1224	break; // IP control
nixnax	167:ff8a2d8beeb1	1225	case 0x0021:
nixnax	142:54d1543e23e5	1226	IPframe();
nixnax	142:54d1543e23e5	1227	break; // IP itself
nixnax	142:54d1543e23e5	1228	default:
nixnax	142:54d1543e23e5	1229	discardedFrame();
nixnax	142:54d1543e23e5	1230	}
nixnax	142:54d1543e23e5	1231	}
nixnax	142:54d1543e23e5	1232
nixnax	146:a45f49a2b29c	1233	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1234	void sniff()
nixnax	146:a45f49a2b29c	1235	{
nixnax	146:a45f49a2b29c	1236	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	1237	}
nixnax	146:a45f49a2b29c	1238
nixnax	142:54d1543e23e5	1239	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1240	void waitForPppFrame()
nixnax	142:54d1543e23e5	1241	{
nixnax	142:54d1543e23e5	1242	while(1) {
nixnax	142:54d1543e23e5	1243	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1244	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1245	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1246	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1247	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1248	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1249	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	181:bcfe7fe2142d	1250	ppp.firstFrame=0; // clear first frame flag
nixnax	142:54d1543e23e5	1251	} else {
nixnax	142:54d1543e23e5	1252	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1253	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1254	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1255	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1256	break;
nixnax	142:54d1543e23e5	1257	}
nixnax	142:54d1543e23e5	1258	}
nixnax	142:54d1543e23e5	1259	}
nixnax	210:a2a651249a9a	1260	// change below to YES to enable the serial to UDP demo
nixnax	210:a2a651249a9a	1261	#define SERIAL_TO_UDP_NO
nixnax	210:a2a651249a9a	1262	#ifdef SERIAL_TO_UDP_YES
nixnax	210:a2a651249a9a	1263	sendUdpData(); // demo that sends characters received on the DEBUG serial port via UDP to another host
nixnax	210:a2a651249a9a	1264	#endif
nixnax	142:54d1543e23e5	1265	}
nixnax	142:54d1543e23e5	1266	}
nixnax	142:54d1543e23e5	1267
nixnax	209:aa514cd631ee	1268	/// Wait for a dial-up modem connect command ("CLIENT") from the host PC, if found, we set ppp.online to true, which starts the IP packet scanner.
nixnax	209:aa514cd631ee	1269	// Note: a 0x7E in the input stream (ppp start of frame character) will also set ppp.online to true - see the code in pppReceiveHandler()
nixnax	153:7993def8663f	1270	void waitForPcConnectString()
nixnax	142:54d1543e23e5	1271	{
nixnax	142:54d1543e23e5	1272	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1273	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1274	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1275	if (found1 != NULL) {
nixnax	209:aa514cd631ee	1276	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	208:73086736610a	1277	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	142:54d1543e23e5	1278	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1279	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1280	}
nixnax	142:54d1543e23e5	1281	}
nixnax	142:54d1543e23e5	1282	}
nixnax	142:54d1543e23e5	1283
nixnax	144:01d98cf7738e	1284	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1285	void initializePpp()
nixnax	142:54d1543e23e5	1286	{
nixnax	210:a2a651249a9a	1287	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	144:01d98cf7738e	1288	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	184:4133f557d4d4	1289	debugPrintf("\x1b[2J\x1b[H\x1b[30m");
nixnax	184:4133f557d4d4	1290	wait_ms(200); // a brief wait so a human can see the reset event
nixnax	184:4133f557d4d4	1291	debugPrintf("mbed PPP-Blinky HTTP & WebSocket server ready :)\n"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax	210:a2a651249a9a	1292	#endif
nixnax	179:ba2b2ddd0da5	1293	pppInitStruct(); // initialize all the variables/properties/buffers
nixnax	179:ba2b2ddd0da5	1294	pc.baud(115200); // pc serial port acting as a dial-up modem - for PPP traffic
nixnax	179:ba2b2ddd0da5	1295	pc.attach(&pppReceiveHandler, RawSerial::RxIrq); // set up serial port receive interrupt handler
nixnax	143:c5019f856a56	1296	}

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

The code in this repository is MIT licensed.