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@216:e3c5a5b47295, 2018-07-22 (annotated)

Committer:: nixnax
Date:: Sun Jul 22 18:49:29 2018 +0000
Revision:: 216:e3c5a5b47295
Parent:: 214:4d832a4877ed
Child:: 217:86498f9ab967

RXBUFLEN can now be any value

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	142:54d1543e23e5	104	<h1><a href=\"http://jsfiddle.net/d26cyuh2/\">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	142:54d1543e23e5	250	for (int i=0; i<8; i++) {
nixnax	145:098b6ed2f7f2	251	ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1; // crc calculator
nixnax	142:54d1543e23e5	252	x>>=1;
nixnax	142:54d1543e23e5	253	}
nixnax	210:a2a651249a9a	254
nixnax	142:54d1543e23e5	255	}
nixnax	142:54d1543e23e5	256
nixnax	145:098b6ed2f7f2	257	/// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax	145:098b6ed2f7f2	258	int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax	142:54d1543e23e5	259	{
nixnax	145:098b6ed2f7f2	260	fcsReset();
nixnax	145:098b6ed2f7f2	261	for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax	145:098b6ed2f7f2	262	return ppp.fcs;
nixnax	142:54d1543e23e5	263	}
nixnax	142:54d1543e23e5	264
nixnax	142:54d1543e23e5	265	/// Get one character from our received PPP buffer
nixnax	142:54d1543e23e5	266	int pc_getBuf()
nixnax	142:54d1543e23e5	267	{
nixnax	142:54d1543e23e5	268	int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax	216:e3c5a5b47295	269	ppp.rx.tail=ppp.rx.tail+1;
nixnax	216:e3c5a5b47295	270	if (ppp.rx.tail > RXBUFLEN) ppp.rx.tail=0;
nixnax	142:54d1543e23e5	271	ppp.rx.buflevel--;
nixnax	142:54d1543e23e5	272	return x;
nixnax	142:54d1543e23e5	273	}
nixnax	142:54d1543e23e5	274
nixnax	142:54d1543e23e5	275	/// Dump a PPP frame to the debug serial port
nixnax	142:54d1543e23e5	276	/// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax	142:54d1543e23e5	277	/// Capture the frame's hex output in your terminal program and save as a text file
nixnax	164:c3de3d212c4b	278	/// In WireShark, use "Import Hex File". Import options are: Offset=None, Protocol=PPP.
nixnax	142:54d1543e23e5	279	void dumpPPPFrame()
nixnax	142:54d1543e23e5	280	{
nixnax	142:54d1543e23e5	281	char pbuf[30];
nixnax	142:54d1543e23e5	282	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	210:a2a651249a9a	283
nixnax	142:54d1543e23e5	284	sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax	210:a2a651249a9a	285
nixnax	142:54d1543e23e5	286	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	287	}
nixnax	210:a2a651249a9a	288
nixnax	142:54d1543e23e5	289	sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax	210:a2a651249a9a	290
nixnax	142:54d1543e23e5	291	putsWhileCheckingInput(pbuf);
nixnax	142:54d1543e23e5	292	}
nixnax	142:54d1543e23e5	293
nixnax	142:54d1543e23e5	294	/// Process a received PPP frame
nixnax	142:54d1543e23e5	295	void processPPPFrame(int start, int end)
nixnax	142:54d1543e23e5	296	{
nixnax	142:54d1543e23e5	297	led1Toggle(); // change led1 state on every frame we receive
nixnax	142:54d1543e23e5	298	if(start==end) {
nixnax	142:54d1543e23e5	299	return; // empty frame
nixnax	142:54d1543e23e5	300	}
nixnax	145:098b6ed2f7f2	301	fcsReset();
nixnax	142:54d1543e23e5	302	char * dest = ppp.pkt.buf;
nixnax	142:54d1543e23e5	303	ppp.pkt.len=0;
nixnax	142:54d1543e23e5	304	int unstuff=0;
nixnax	142:54d1543e23e5	305	int idx = start;
nixnax	142:54d1543e23e5	306	while(1) {
nixnax	210:a2a651249a9a	307
nixnax	142:54d1543e23e5	308	if (unstuff==0) {
nixnax	142:54d1543e23e5	309	if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax	142:54d1543e23e5	310	else {
nixnax	142:54d1543e23e5	311	*dest = ppp.rx.buf[idx];
nixnax	142:54d1543e23e5	312	ppp.pkt.len++;
nixnax	142:54d1543e23e5	313	dest++;
nixnax	145:098b6ed2f7f2	314	fcsDo(ppp.rx.buf[idx]);
nixnax	142:54d1543e23e5	315	}
nixnax	142:54d1543e23e5	316	} else { // unstuff characters prefixed with 0x7d
nixnax	142:54d1543e23e5	317	*dest = ppp.rx.buf[idx]^0x20;
nixnax	142:54d1543e23e5	318	ppp.pkt.len++;
nixnax	142:54d1543e23e5	319	dest++;
nixnax	145:098b6ed2f7f2	320	fcsDo(ppp.rx.buf[idx]^0x20);
nixnax	142:54d1543e23e5	321	unstuff=0;
nixnax	142:54d1543e23e5	322	}
nixnax	216:e3c5a5b47295	323	idx = idx+1;
nixnax	216:e3c5a5b47295	324	if (idx > RXBUFLEN) idx=0;
nixnax	142:54d1543e23e5	325	if (idx == end) break;
nixnax	142:54d1543e23e5	326	}
nixnax	145:098b6ed2f7f2	327	ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax	142:54d1543e23e5	328	if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax	142:54d1543e23e5	329	if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax	142:54d1543e23e5	330	determinePacketType();
nixnax	142:54d1543e23e5	331	} else {
nixnax	142:54d1543e23e5	332	#define REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	333	#ifdef REPORT_FCS_ERROR_YES
nixnax	142:54d1543e23e5	334	char pbuf[50]; // local print buffer
nixnax	210:a2a651249a9a	335
nixnax	142:54d1543e23e5	336	sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax	210:a2a651249a9a	337
nixnax	142:54d1543e23e5	338	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	339	if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax	142:54d1543e23e5	340	#endif
nixnax	142:54d1543e23e5	341	}
nixnax	142:54d1543e23e5	342	}
nixnax	142:54d1543e23e5	343
nixnax	142:54d1543e23e5	344	/// output a character to the PPP port while checking for incoming characters
nixnax	142:54d1543e23e5	345	void pcPutcWhileCheckingInput(int ch)
nixnax	142:54d1543e23e5	346	{
nixnax	210:a2a651249a9a	347
nixnax	142:54d1543e23e5	348	pc.putc(ch);
nixnax	210:a2a651249a9a	349
nixnax	142:54d1543e23e5	350	}
nixnax	142:54d1543e23e5	351
nixnax	142:54d1543e23e5	352	/// do PPP HDLC-like handling of special (flag) characters
nixnax	143:c5019f856a56	353	void hdlcPut(int ch)
nixnax	142:54d1543e23e5	354	{
nixnax	142:54d1543e23e5	355	if ( (ch<0x20) \|\| (ch==0x7d) \|\| (ch==0x7e) ) {
nixnax	142:54d1543e23e5	356	pcPutcWhileCheckingInput(0x7d);
nixnax	142:54d1543e23e5	357	pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax	142:54d1543e23e5	358	} else {
nixnax	142:54d1543e23e5	359	pcPutcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	360	}
nixnax	142:54d1543e23e5	361	}
nixnax	142:54d1543e23e5	362
nixnax	142:54d1543e23e5	363	/// send a PPP frame in HDLC format
nixnax	144:01d98cf7738e	364	void sendPppFrame()
nixnax	143:c5019f856a56	365	{
nixnax	172:449dd7a28955	366	ppp.responseCounter++; // count the number of ppp frames we send
nixnax	145:098b6ed2f7f2	367	int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax	142:54d1543e23e5	368	ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax	142:54d1543e23e5	369	ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax	142:54d1543e23e5	370	pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax	142:54d1543e23e5	371	for(int i=0; i<ppp.pkt.len; i++) {
nixnax	142:54d1543e23e5	372	wait_us(86); // wait one character time
nixnax	210:a2a651249a9a	373
nixnax	142:54d1543e23e5	374	hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax	142:54d1543e23e5	375	}
nixnax	142:54d1543e23e5	376	pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax	142:54d1543e23e5	377	}
nixnax	142:54d1543e23e5	378
nixnax	143:c5019f856a56	379	/// 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	380	int bufferToIP(char * buffer)
nixnax	143:c5019f856a56	381	{
nixnax	143:c5019f856a56	382	int result=0;
nixnax	143:c5019f856a56	383	for(int i=0; i<4; i++) result = (result<<8)\|(*buffer++ & 0xff);
nixnax	143:c5019f856a56	384	return result;
nixnax	143:c5019f856a56	385	}
nixnax	143:c5019f856a56	386
nixnax	177:dab9e685af53	387	/// convert 4-byte ip address to 32-bit
nixnax	179:ba2b2ddd0da5	388	unsigned int ip( int a, int b, int c, int d)
nixnax	179:ba2b2ddd0da5	389	{
nixnax	177:dab9e685af53	390	return a<<24 \| b<<16 \| c<<8 \| d;
nixnax	177:dab9e685af53	391	}
nixnax	177:dab9e685af53	392
nixnax	142:54d1543e23e5	393	/// handle IPCP configuration requests
nixnax	142:54d1543e23e5	394	void ipcpConfigRequestHandler()
nixnax	142:54d1543e23e5	395	{
nixnax	142:54d1543e23e5	396	debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax	173:6774a0c851c4	397	if(ppp.ipcp->request[0]==3) {
nixnax	143:c5019f856a56	398	ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax	173:6774a0c851c4	399	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	400	}
nixnax	143:c5019f856a56	401
nixnax	167:ff8a2d8beeb1	402	ppp.ipcp->code=2; // change code to ack
nixnax	144:01d98cf7738e	403	sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax	142:54d1543e23e5	404
nixnax	142:54d1543e23e5	405	debugPrintf("Our IPCP Ask (no options)\n");
nixnax	167:ff8a2d8beeb1	406	ppp.ipcp->code=1; // change code to request
nixnax	167:ff8a2d8beeb1	407	ppp.ipcp->lengthR = __REV16( 4 ); // 4 is minimum length - no options in this request
nixnax	167:ff8a2d8beeb1	408	ppp.pkt.len=4+4+2; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax	144:01d98cf7738e	409	sendPppFrame(); // send our request
nixnax	142:54d1543e23e5	410	}
nixnax	142:54d1543e23e5	411
nixnax	142:54d1543e23e5	412	/// handle IPCP acknowledge (do nothing)
nixnax	142:54d1543e23e5	413	void ipcpAckHandler()
nixnax	142:54d1543e23e5	414	{
nixnax	142:54d1543e23e5	415	debugPrintf("Their IPCP Grant\n");
nixnax	142:54d1543e23e5	416	}
nixnax	142:54d1543e23e5	417
nixnax	143:c5019f856a56	418	/// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax	143:c5019f856a56	419	/// 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	420	void ipcpNackHandler()
nixnax	142:54d1543e23e5	421	{
nixnax	146:a45f49a2b29c	422	debugPrintf("Their IPCP Nack\n");
nixnax	173:6774a0c851c4	423	if (ppp.ipcp->request[0]==3) { // check if the NACK contains an IP address parameter
nixnax	167:ff8a2d8beeb1	424	ppp.ipcp->code=1; // assume the NACK contains our "suggested" IP address
nixnax	144:01d98cf7738e	425	sendPppFrame(); // let's request this IP address as ours
nixnax	143:c5019f856a56	426	debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax	146:a45f49a2b29c	427	} else { // if it's not an IP nack we ignore it
nixnax	146:a45f49a2b29c	428	debugPrintf("IPCP Nack Ignored\n");
nixnax	146:a45f49a2b29c	429	}
nixnax	142:54d1543e23e5	430	}
nixnax	142:54d1543e23e5	431
nixnax	142:54d1543e23e5	432	/// handle all other IPCP requests (by ignoring them)
nixnax	142:54d1543e23e5	433	void ipcpDefaultHandler()
nixnax	142:54d1543e23e5	434	{
nixnax	142:54d1543e23e5	435	debugPrintf("Their IPCP Other\n");
nixnax	142:54d1543e23e5	436	}
nixnax	142:54d1543e23e5	437
nixnax	142:54d1543e23e5	438	/// process an incoming IPCP packet
nixnax	142:54d1543e23e5	439	void IPCPframe()
nixnax	142:54d1543e23e5	440	{
nixnax	167:ff8a2d8beeb1	441	int action = ppp.ipcp->code; // packet type is here
nixnax	167:ff8a2d8beeb1	442	switch (action) {
nixnax	142:54d1543e23e5	443	case 1:
nixnax	142:54d1543e23e5	444	ipcpConfigRequestHandler();
nixnax	142:54d1543e23e5	445	break;
nixnax	142:54d1543e23e5	446	case 2:
nixnax	142:54d1543e23e5	447	ipcpAckHandler();
nixnax	142:54d1543e23e5	448	break;
nixnax	142:54d1543e23e5	449	case 3:
nixnax	142:54d1543e23e5	450	ipcpNackHandler();
nixnax	142:54d1543e23e5	451	break;
nixnax	142:54d1543e23e5	452	default:
nixnax	142:54d1543e23e5	453	ipcpDefaultHandler();
nixnax	142:54d1543e23e5	454	}
nixnax	142:54d1543e23e5	455	}
nixnax	142:54d1543e23e5	456
nixnax	142:54d1543e23e5	457	/// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax	161:d59f778bc8ab	458	unsigned int dataCheckSum(char * ptr, int len, int restart)
nixnax	142:54d1543e23e5	459	{
nixnax	159:4d1bf96a59cd	460	unsigned int i,hi,lo;
nixnax	142:54d1543e23e5	461	unsigned char placeHolder;
nixnax	161:d59f778bc8ab	462	if (restart) ppp.sum=0;
nixnax	142:54d1543e23e5	463	if (len&1) {
nixnax	142:54d1543e23e5	464	placeHolder = ptr[len];
nixnax	142:54d1543e23e5	465	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	466	}
nixnax	142:54d1543e23e5	467	i=0;
nixnax	142:54d1543e23e5	468	while ( i<len ) {
nixnax	210:a2a651249a9a	469
nixnax	142:54d1543e23e5	470	hi = ptr[i++];
nixnax	142:54d1543e23e5	471	lo = ptr[i++];
nixnax	159:4d1bf96a59cd	472	ppp.sum = ppp.sum + ((hi<<8)\|lo);
nixnax	142:54d1543e23e5	473	}
nixnax	142:54d1543e23e5	474	if (len&1) {
nixnax	142:54d1543e23e5	475	ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax	142:54d1543e23e5	476	}
nixnax	159:4d1bf96a59cd	477	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax	159:4d1bf96a59cd	478	ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax	159:4d1bf96a59cd	479	return ~ppp.sum;
nixnax	142:54d1543e23e5	480	}
nixnax	142:54d1543e23e5	481
nixnax	142:54d1543e23e5	482	/// perform the checksum on an IP header
nixnax	146:a45f49a2b29c	483	void IpHeaderCheckSum()
nixnax	142:54d1543e23e5	484	{
nixnax	161:d59f778bc8ab	485	ppp.ip->checksumR=0; // zero the checsum in the IP header
nixnax	161:d59f778bc8ab	486	int len = 4 * ppp.ip->headerLength; // length of IP header in bytes
nixnax	161:d59f778bc8ab	487	unsigned int sum = dataCheckSum(ppp.ipStart,len,1);
nixnax	161:d59f778bc8ab	488	ppp.ip->checksumR = __REV16( sum ); // insert fresh checksum
nixnax	146:a45f49a2b29c	489	}
nixnax	146:a45f49a2b29c	490
nixnax	147:0f40005cbc5f	491	/// swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	492	void swapIpAddresses()
nixnax	147:0f40005cbc5f	493	{
nixnax	162:594729c0e5c1	494	unsigned int tempHold;
nixnax	162:594729c0e5c1	495	tempHold = ppp.ip->srcAdrR; // tempHold <- source IP
nixnax	162:594729c0e5c1	496	ppp.ip->srcAdrR = ppp.ip->dstAdrR; // source <- dest
nixnax	162:594729c0e5c1	497	ppp.ip->dstAdrR = tempHold; // dest <- tempHold*/
nixnax	147:0f40005cbc5f	498	}
nixnax	147:0f40005cbc5f	499
nixnax	149:969d98f6fb88	500	/// swap the IP source and destination ports
nixnax	149:969d98f6fb88	501	void swapIpPorts()
nixnax	149:969d98f6fb88	502	{
nixnax	173:6774a0c851c4	503	int headerSizeIP = 4 * (ppp.ip->headerLength); // calculate size of IP header
nixnax	173:6774a0c851c4	504	char * ipSrcPort = ppp.ipStart + headerSizeIP + 0; // ip source port location
nixnax	173:6774a0c851c4	505	char * ipDstPort = ppp.ipStart + headerSizeIP + 2; // ip destin port location
nixnax	149:969d98f6fb88	506	char tempHold[2];
nixnax	149:969d98f6fb88	507	memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax	149:969d98f6fb88	508	memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax	149:969d98f6fb88	509	memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax	149:969d98f6fb88	510	}
nixnax	149:969d98f6fb88	511
nixnax	170:3d3b2126181c	512	/// Build the "pseudo header" required for UDP and TCP, then calculate its checksum
nixnax	170:3d3b2126181c	513	void checkSumPseudoHeader( unsigned int packetLength )
nixnax	170:3d3b2126181c	514	{
nixnax	170:3d3b2126181c	515	// 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	516	pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax	170:3d3b2126181c	517	pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax	170:3d3b2126181c	518	pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax	170:3d3b2126181c	519	pseudoHeader.zero = 0; // zero byte
nixnax	170:3d3b2126181c	520	pseudoHeader.protocol = ppp.ip->protocol; // protocol number (udp or tcp)
nixnax	170:3d3b2126181c	521	pseudoHeader.lengthR = __REV16( packetLength ); // size of tcp or udp packet
nixnax	170:3d3b2126181c	522	dataCheckSum(pseudoHeader.start, 12, 1); // calculate this header's checksum
nixnax	170:3d3b2126181c	523	}
nixnax	170:3d3b2126181c	524
nixnax	171:46b36d4edd1d	525	/// initialize an IP packet to send
nixnax	171:46b36d4edd1d	526	void initIP (unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, unsigned int protocol)
nixnax	171:46b36d4edd1d	527	{
nixnax	171:46b36d4edd1d	528	ppp.ppp->address = 0xff;
nixnax	171:46b36d4edd1d	529	ppp.ppp->control = 3;
nixnax	171:46b36d4edd1d	530	ppp.ppp->protocolR = __REV16( 0x0021 );
nixnax	171:46b36d4edd1d	531	ppp.ip->version = 4;
nixnax	171:46b36d4edd1d	532	ppp.ip->headerLength = 5; // 5 words = 20 bytes
nixnax	171:46b36d4edd1d	533	ppp.ip->identR = __REV16(ppp.ipData.ident++); // insert our ident
nixnax	171:46b36d4edd1d	534	ppp.ip->dontFragment=1;
nixnax	171:46b36d4edd1d	535	ppp.ip->ttl=128;
nixnax	171:46b36d4edd1d	536	ppp.ip->protocol = protocol; // udp
nixnax	171:46b36d4edd1d	537	ppp.ip->srcAdrR = __REV(srcIp);
nixnax	171:46b36d4edd1d	538	ppp.ip->dstAdrR = __REV(dstIp);
nixnax	171:46b36d4edd1d	539	ppp.udpStart = ppp.ipStart + 20; // calculate start of udp header
nixnax	171:46b36d4edd1d	540	ppp.udp->srcPortR = __REV16(srcPort); // source port
nixnax	171:46b36d4edd1d	541	ppp.udp->dstPortR = __REV16(dstPort); // dest port
nixnax	171:46b36d4edd1d	542	}
nixnax	171:46b36d4edd1d	543
nixnax	171:46b36d4edd1d	544
nixnax	171:46b36d4edd1d	545	/// Build a UDP packet from scratch
nixnax	171:46b36d4edd1d	546	void sendUdp(unsigned int srcIp, unsigned int dstIp, unsigned int srcPort, unsigned int dstPort, char * message,int msgLen)
nixnax	171:46b36d4edd1d	547	{
nixnax	171:46b36d4edd1d	548	struct {
nixnax	171:46b36d4edd1d	549	unsigned int ipAll; // length of entire ip packet
nixnax	171:46b36d4edd1d	550	unsigned int ipHeader; // length of ip header
nixnax	171:46b36d4edd1d	551	unsigned int udpAll; // length of entire udp packet
nixnax	171:46b36d4edd1d	552	unsigned int udpData; // length of udp data segment
nixnax	171:46b36d4edd1d	553	} len;
nixnax	171:46b36d4edd1d	554	len.ipHeader = 20; // ip header length
nixnax	171:46b36d4edd1d	555	len.udpData = msgLen; // udp data size
nixnax	171:46b36d4edd1d	556	len.udpAll = len.udpData+8; // update local udp packet length
nixnax	171:46b36d4edd1d	557	len.ipAll = len.ipHeader + len.udpAll; // update IP Length
nixnax	171:46b36d4edd1d	558	initIP(srcIp, dstIp, srcPort, dstPort, 17); // init a UDP packet
nixnax	171:46b36d4edd1d	559	ppp.ip->lengthR = __REV16(len.ipAll); // update IP length in buffer
nixnax	171:46b36d4edd1d	560	ppp.udpStart = ppp.ipStart + len.ipHeader; // calculate start of udp header
nixnax	171:46b36d4edd1d	561	memcpy( ppp.udp->data, message, len.udpData ); // copy the message to the buffer
nixnax	171:46b36d4edd1d	562	ppp.udp->lengthR = __REV16(len.udpAll); // update UDP length in buffer
nixnax	171:46b36d4edd1d	563	ppp.pkt.len = len.ipAll+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	564	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	565	checkSumPseudoHeader( len.udpAll ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	566	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	567	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,len.udpAll, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	568	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	569	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	570	}
nixnax	171:46b36d4edd1d	571
nixnax	146:a45f49a2b29c	572	/// Process an incoming UDP packet.
nixnax	146:a45f49a2b29c	573	/// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax	146:a45f49a2b29c	574	void UDPpacket()
nixnax	146:a45f49a2b29c	575	{
nixnax	163:d1b4328e9f08	576	struct {
nixnax	163:d1b4328e9f08	577	unsigned int all; // length of entire ip packet
nixnax	163:d1b4328e9f08	578	unsigned int header; // length of ip header
nixnax	163:d1b4328e9f08	579	} ipLength;
nixnax	163:d1b4328e9f08	580
nixnax	163:d1b4328e9f08	581	struct {
nixnax	165:c47826d07e0d	582	unsigned int all; // length of entire udp packet
nixnax	163:d1b4328e9f08	583	unsigned int data; // length of udp data segment
nixnax	163:d1b4328e9f08	584	} udpLength;
nixnax	163:d1b4328e9f08	585
nixnax	163:d1b4328e9f08	586	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	163:d1b4328e9f08	587	ppp.udpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	171:46b36d4edd1d	588	udpLength.all = __REV16( ppp.udp->lengthR ); // size of udp packet
nixnax	163:d1b4328e9f08	589	udpLength.data = udpLength.all - 8; // size of udp data
nixnax	147:0f40005cbc5f	590
nixnax	146:a45f49a2b29c	591	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	171:46b36d4edd1d	592	char * srcIP = ppp.ip->srcAdrPtr; // IP source
nixnax	171:46b36d4edd1d	593	char * dstIP = ppp.ip->dstAdrPtr; //IP destination
nixnax	163:d1b4328e9f08	594
nixnax	171:46b36d4edd1d	595	unsigned int udpSrcPort = __REV16( ppp.udp->srcPortR ); // integer of UDP source port
nixnax	171:46b36d4edd1d	596	unsigned int udpDstPort = __REV16( ppp.udp->dstPortR ); // integer of UDP dest port
nixnax	163:d1b4328e9f08	597
nixnax	163:d1b4328e9f08	598	if(v0) {
nixnax	163:d1b4328e9f08	599	debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrcPort);
nixnax	163:d1b4328e9f08	600	debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDstPort);
nixnax	163:d1b4328e9f08	601	debugPrintf("Len %03d", udpLength);
nixnax	163:d1b4328e9f08	602	}
nixnax	146:a45f49a2b29c	603	if (v1) {
nixnax	163:d1b4328e9f08	604	int printSize = udpLength.data;
nixnax	146:a45f49a2b29c	605	if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax	146:a45f49a2b29c	606	for (int i=0; i<printSize; i++) {
nixnax	163:d1b4328e9f08	607	char ch = ppp.udp->data[i];
nixnax	146:a45f49a2b29c	608	if (ch>31 && ch<127) {
nixnax	146:a45f49a2b29c	609	debugPrintf("%c", ch);
nixnax	146:a45f49a2b29c	610	} else {
nixnax	146:a45f49a2b29c	611	debugPrintf("_");
nixnax	146:a45f49a2b29c	612	}
nixnax	146:a45f49a2b29c	613	}
nixnax	146:a45f49a2b29c	614	}
nixnax	146:a45f49a2b29c	615	if (v0) debugPrintf("\n");
nixnax	146:a45f49a2b29c	616	#endif
nixnax	163:d1b4328e9f08	617	int echoFound = !strncmp(ppp.udp->data,"echo ",5); // true if UDP message starts with "echo "
nixnax	163:d1b4328e9f08	618	int testFound = !strncmp(ppp.udp->data,"test" ,4); // true if UDP message starts with "test"
nixnax	146:a45f49a2b29c	619	if ( (echoFound) \|\| (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax	146:a45f49a2b29c	620	if (echoFound) {
nixnax	171:46b36d4edd1d	621	swapIpAddresses(); // swap IP source and destination
nixnax	171:46b36d4edd1d	622	swapIpPorts(); // swap IP source and destination ports
nixnax	163:d1b4328e9f08	623	memcpy(ppp.udp->data,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax	170:3d3b2126181c	624	int n=0;
nixnax	170:3d3b2126181c	625	n=n+sprintf(n+ppp.udp->data+udpLength.data, "} UDP Server: PPP-Blinky\n"); // an appendix
nixnax	168:c77eb908042a	626	udpLength.data = udpLength.data + n; // update udp data size with the size of the appendix
nixnax	171:46b36d4edd1d	627	// we may have changed data length, update all the lengths
nixnax	171:46b36d4edd1d	628	udpLength.all = udpLength.data+8; // update local udp packet length
nixnax	171:46b36d4edd1d	629	ipLength.all = ipLength.header + udpLength.all; // update IP Length
nixnax	171:46b36d4edd1d	630	ppp.ip->lengthR = __REV16(ipLength.all); // update IP length in buffer
nixnax	171:46b36d4edd1d	631	ppp.udp->lengthR = __REV16(udpLength.all); // update UDP length in buffer
nixnax	171:46b36d4edd1d	632	ppp.pkt.len = ipLength.all+2+4; // update ppp packet length
nixnax	171:46b36d4edd1d	633	IpHeaderCheckSum(); // refresh IP header checksum
nixnax	171:46b36d4edd1d	634	checkSumPseudoHeader( udpLength.all ); // get the UDP pseudo-header checksum
nixnax	171:46b36d4edd1d	635	ppp.udp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	171:46b36d4edd1d	636	unsigned int pseudoHeaderSum=dataCheckSum(ppp.udpStart,udpLength.all, 0); // continue the TCP checksum on the whole TCP packet
nixnax	171:46b36d4edd1d	637	ppp.udp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	171:46b36d4edd1d	638	sendPppFrame(); // send the UDP message back
nixnax	171:46b36d4edd1d	639	} else if ( testFound ) {
nixnax	171:46b36d4edd1d	640	unsigned int sI = __REV( ppp.ip->srcAdrR );
nixnax	171:46b36d4edd1d	641	unsigned int dI = __REV( ppp.ip->dstAdrR );
nixnax	171:46b36d4edd1d	642	unsigned int sp = __REV16( ppp.udp->srcPortR );
nixnax	171:46b36d4edd1d	643	unsigned int dp = __REV16( ppp.udp->dstPortR );
nixnax	172:449dd7a28955	644	int n=sprintf(ppp.pkt.buf+200,"Response Count %d\n", ppp.responseCounter);
nixnax	171:46b36d4edd1d	645	sendUdp(dI,sI,dp,sp,ppp.pkt.buf+200,n); // build a udp packet from the ground up
nixnax	146:a45f49a2b29c	646	}
nixnax	146:a45f49a2b29c	647	}
nixnax	142:54d1543e23e5	648	}
nixnax	142:54d1543e23e5	649
nixnax	174:e5a3f16421a5	650	/// UDP demo that sends a udp packet containing a character received from the second debug serial port.
nixnax	174:e5a3f16421a5	651	/// Sends a 48 byte IP/UDP header for every 1 byte of data so line-mode would probably be better.
nixnax	178:3f17aa0ce5ce	652	/// If you want ip packets from ppp blinky to be routed to other networks, ensure you have ip routing enabled.
nixnax	178:3f17aa0ce5ce	653	/// See http://www.wikihow.com/Enable-IP-Routing.
nixnax	179:ba2b2ddd0da5	654	/// Also ensure that the firewall on the receiving machine has the receiving UDP port (12345 in this example) enabled.
nixnax	179:ba2b2ddd0da5	655	/// The netcat UDP receive command on the remote host would be: nc -ul 12345
nixnax	174:e5a3f16421a5	656	void sendUdpData()
nixnax	174:e5a3f16421a5	657	{
nixnax	174:e5a3f16421a5	658	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	179:ba2b2ddd0da5	659	if (ppp.online) {
nixnax	179:ba2b2ddd0da5	660	if (xx.readable()) {
nixnax	179:ba2b2ddd0da5	661	char inchar = xx.getc();
nixnax	179:ba2b2ddd0da5	662	xx.putc( inchar ); // echo the received character on the debug serial port
nixnax	179:ba2b2ddd0da5	663	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	664	}
nixnax	174:e5a3f16421a5	665	}
nixnax	174:e5a3f16421a5	666	#endif
nixnax	174:e5a3f16421a5	667	}
nixnax	174:e5a3f16421a5	668
nixnax	142:54d1543e23e5	669	/// handle a PING ICMP (internet control message protocol) packet
nixnax	142:54d1543e23e5	670	void ICMPpacket() // internet control message protocol
nixnax	142:54d1543e23e5	671	{
nixnax	165:c47826d07e0d	672	struct {
nixnax	165:c47826d07e0d	673	unsigned int all; // length of entire ip packet
nixnax	165:c47826d07e0d	674	unsigned int header; // length of ip header
nixnax	165:c47826d07e0d	675	} ipLength;
nixnax	165:c47826d07e0d	676	struct {
nixnax	165:c47826d07e0d	677	unsigned int all; // length of entire udp packet
nixnax	165:c47826d07e0d	678	unsigned int data; // length of udp data segment
nixnax	165:c47826d07e0d	679	} icmpLength;
nixnax	165:c47826d07e0d	680	ipLength.all = __REV16( ppp.ip->lengthR ); // length of ip packet
nixnax	165:c47826d07e0d	681	ipLength.header = 4 * ppp.ip->headerLength; // length of ip header
nixnax	165:c47826d07e0d	682	ppp.icmpStart = ppp.ipStart + ipLength.header; // calculate start of udp header
nixnax	165:c47826d07e0d	683	icmpLength.all = ipLength.all - ipLength.header; // length of icmp packet
nixnax	165:c47826d07e0d	684	icmpLength.data = icmpLength.all - 8; // length of icmp data
nixnax	142:54d1543e23e5	685	#define ICMP_TYPE_PING_REQUEST 8
nixnax	165:c47826d07e0d	686	if ( ppp.icmp->type == ICMP_TYPE_PING_REQUEST ) {
nixnax	165:c47826d07e0d	687	ppp.ip->ttl--; // decrement time to live (so we have to update header checksum)
nixnax	147:0f40005cbc5f	688	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	167:ff8a2d8beeb1	689	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	690	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	165:c47826d07e0d	691	int icmpIdent = __REV16( ppp.ip->identR ); // byte reversed - big endian
nixnax	165:c47826d07e0d	692	int icmpSequence = __REV16( ppp.icmp->sequenceR ); // byte reversed - big endian
nixnax	142:54d1543e23e5	693	if(1) {
nixnax	142:54d1543e23e5	694	char pbuf[50];
nixnax	210:a2a651249a9a	695
nixnax	142:54d1543e23e5	696	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	697	putsWhileCheckingInput( pbuf );
nixnax	210:a2a651249a9a	698
nixnax	142:54d1543e23e5	699	sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax	210:a2a651249a9a	700
nixnax	142:54d1543e23e5	701	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	702	}
nixnax	142:54d1543e23e5	703	#endif
nixnax	147:0f40005cbc5f	704	swapIpAddresses(); // swap the IP source and destination addresses
nixnax	147:0f40005cbc5f	705	IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax	142:54d1543e23e5	706	#define ICMP_TYPE_ECHO_REPLY 0
nixnax	165:c47826d07e0d	707	ppp.icmp->type = ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax	165:c47826d07e0d	708	ppp.icmp->checkSumR = 0; // zero the checksum for recalculation
nixnax	165:c47826d07e0d	709	unsigned int sum = dataCheckSum(ppp.icmpStart, icmpLength.all, 1); // icmp checksum
nixnax	165:c47826d07e0d	710	ppp.icmp->checkSumR = __REV16( sum ); // save big-endian icmp checksum
nixnax	142:54d1543e23e5	711
nixnax	165:c47826d07e0d	712	int printSize = icmpLength.data; // exclude size of icmp header
nixnax	142:54d1543e23e5	713	if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax	142:54d1543e23e5	714	if (0) {
nixnax	142:54d1543e23e5	715	for (int i=0; i<printSize; i++) {
nixnax	165:c47826d07e0d	716	char ch = ppp.icmp->data[i];
nixnax	142:54d1543e23e5	717	if (ch>31 && ch<127) {
nixnax	142:54d1543e23e5	718	putcWhileCheckingInput(ch);
nixnax	142:54d1543e23e5	719	} else {
nixnax	142:54d1543e23e5	720	putcWhileCheckingInput('_');
nixnax	142:54d1543e23e5	721	}
nixnax	142:54d1543e23e5	722	}
nixnax	142:54d1543e23e5	723	putcWhileCheckingInput('\n');
nixnax	142:54d1543e23e5	724	}
nixnax	144:01d98cf7738e	725	sendPppFrame(); // reply to the ping
nixnax	142:54d1543e23e5	726	} else {
nixnax	142:54d1543e23e5	727	if (v0) {
nixnax	165:c47826d07e0d	728	debugPrintf("ICMP type=%x \n", ppp.icmp->type);
nixnax	142:54d1543e23e5	729	}
nixnax	142:54d1543e23e5	730	}
nixnax	142:54d1543e23e5	731	}
nixnax	142:54d1543e23e5	732
nixnax	142:54d1543e23e5	733	/// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax	142:54d1543e23e5	734	void IGMPpacket()
nixnax	142:54d1543e23e5	735	{
nixnax	142:54d1543e23e5	736	if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax	142:54d1543e23e5	737	}
nixnax	142:54d1543e23e5	738
nixnax	142:54d1543e23e5	739	/// dump the header of an IP pakcet on the (optional) debug serial port
nixnax	142:54d1543e23e5	740	void dumpHeaderIP (int outGoing)
nixnax	142:54d1543e23e5	741	{
nixnax	142:54d1543e23e5	742	#if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	210:a2a651249a9a	743
nixnax	155:9c6a1d249e26	744	int IPv4Id = __REV16(ppp.ip->identR);
nixnax	152:025c73b6c0a9	745	char pbuf[80]; // local print buffer
nixnax	142:54d1543e23e5	746	int n=0;
nixnax	142:54d1543e23e5	747	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	142:54d1543e23e5	748	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	749	#define DUMP_FULL_IP_ADDRESS_YES
nixnax	142:54d1543e23e5	750	#ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax	167:ff8a2d8beeb1	751	char * srcAdr = ppp.ip->srcAdrPtr;
nixnax	167:ff8a2d8beeb1	752	char * dstAdr = ppp.ip->dstAdrPtr;
nixnax	142:54d1543e23e5	753	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	754	#endif
nixnax	142:54d1543e23e5	755	putsWhileCheckingInput( pbuf );
nixnax	142:54d1543e23e5	756	#ifndef TCP_HEADER_DUMP_YES
nixnax	160:bd701ad564cb	757	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	758	#endif
nixnax	142:54d1543e23e5	759	#endif
nixnax	142:54d1543e23e5	760	}
nixnax	142:54d1543e23e5	761
nixnax	142:54d1543e23e5	762	/// dump a TCP header on the optional debug serial port
nixnax	142:54d1543e23e5	763	void dumpHeaderTCP(int outGoing)
nixnax	142:54d1543e23e5	764	{
nixnax	142:54d1543e23e5	765	#if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax	155:9c6a1d249e26	766	char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax	142:54d1543e23e5	767	#define PRINT_ALL_TCP_FLAGS_YES
nixnax	142:54d1543e23e5	768	#ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax	155:9c6a1d249e26	769	memset(flagString,'.', 8); // fill string with "........"
nixnax	156:163c23249731	770	if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax	156:163c23249731	771	if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax	156:163c23249731	772	if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax	156:163c23249731	773	if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax	156:163c23249731	774	if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax	156:163c23249731	775	if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax	156:163c23249731	776	if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax	156:163c23249731	777	if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax	155:9c6a1d249e26	778	flagString[8]=0; // null terminate string
nixnax	142:54d1543e23e5	779	#else
nixnax	156:163c23249731	780	if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax	156:163c23249731	781	if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax	156:163c23249731	782	if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax	156:163c23249731	783	if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax	156:163c23249731	784	if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax	155:9c6a1d249e26	785	flagString[1]=0; // null terminate string
nixnax	142:54d1543e23e5	786	#endif
nixnax	155:9c6a1d249e26	787	putsWhileCheckingInput( flagString );
nixnax	142:54d1543e23e5	788	#define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	789	#ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax	142:54d1543e23e5	790	putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax	160:bd701ad564cb	791	#else
nixnax	160:bd701ad564cb	792	putsWhileCheckingInput("\x1b[30m"); // write a black color after every packet
nixnax	142:54d1543e23e5	793	#endif
nixnax	156:163c23249731	794	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	795	putcWhileCheckingInput('\n'); // insert an extra new line to mark the end (except for final ack) of an HTTP conversation
nixnax	142:54d1543e23e5	796	}
nixnax	142:54d1543e23e5	797	#endif
nixnax	142:54d1543e23e5	798	}
nixnax	142:54d1543e23e5	799
nixnax	143:c5019f856a56	800	/// Encode a buffer in base-64
nixnax	184:4133f557d4d4	801	const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax	142:54d1543e23e5	802	void enc64(char * in, char * out, int len)
nixnax	142:54d1543e23e5	803	{
nixnax	142:54d1543e23e5	804	int i,j,a,b,c;
nixnax	142:54d1543e23e5	805	i=0;
nixnax	142:54d1543e23e5	806	j=0;
nixnax	142:54d1543e23e5	807	while(1) {
nixnax	142:54d1543e23e5	808	if (i<len) {
nixnax	142:54d1543e23e5	809	a = in[i++];
nixnax	142:54d1543e23e5	810	out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax	142:54d1543e23e5	811	} else break;
nixnax	142:54d1543e23e5	812	if (i<len) {
nixnax	142:54d1543e23e5	813	b = in[i++];
nixnax	142:54d1543e23e5	814	out[j++] = lut[ ( (a << 4) & 0x30) \| ( (b >> 4) & 0x0f) ];
nixnax	142:54d1543e23e5	815	out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax	142:54d1543e23e5	816	} else out[j++] = '=';
nixnax	142:54d1543e23e5	817	if (i<len) {
nixnax	142:54d1543e23e5	818	c = in[i++];
nixnax	142:54d1543e23e5	819	j--;
nixnax	142:54d1543e23e5	820	out[j++] = lut[ ( (b << 2) & 0x3c) \| ( (c >> 6) & 0x03) ];
nixnax	142:54d1543e23e5	821	out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax	142:54d1543e23e5	822	} else out[j++] = '=';
nixnax	142:54d1543e23e5	823	}
nixnax	142:54d1543e23e5	824	out[j]=0;
nixnax	142:54d1543e23e5	825	}
nixnax	142:54d1543e23e5	826
nixnax	160:bd701ad564cb	827	/// Handle a request for an http websocket.
nixnax	160:bd701ad564cb	828	/// 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	829	int webSocketHandler(char * dataStart)
nixnax	142:54d1543e23e5	830	{
nixnax	142:54d1543e23e5	831	int n=0; // byte counter
nixnax	184:4133f557d4d4	832	char * key = strstr(dataStart, "Sec-WebSocket-Key:"); // search for the key in the payload
nixnax	142:54d1543e23e5	833	if (key != NULL) {
nixnax	184:4133f557d4d4	834	key = key + 18; // skip over the key ident string "Sec-WebSocket-Key:"
nixnax	142:54d1543e23e5	835	if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax	184:4133f557d4d4	836	while ( strchr(lut, *key) == NULL) key++; // skip non-valid base-64 characters (whitespace)
nixnax	184:4133f557d4d4	837	char challenge [80];
nixnax	184:4133f557d4d4	838	int i=0;
nixnax	184:4133f557d4d4	839	char * copyTo = challenge;
nixnax	184:4133f557d4d4	840	while (strchr(lut, *key) != NULL) { // copy while we see valid base-64 characters
nixnax	184:4133f557d4d4	841	if (i++ >40) break; // prevent buffer overflow
nixnax	184:4133f557d4d4	842	copyTo++ = key++; // copy next valid base-64 character
nixnax	184:4133f557d4d4	843	}
nixnax	184:4133f557d4d4	844	strcpy(copyTo,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"); // append websocket gui code
nixnax	184:4133f557d4d4	845	if (0) debugPrintf("Challenge is %s\n", challenge); // the string we hash for the challenge
nixnax	142:54d1543e23e5	846	char shaOutput [20]; // sha1 output
nixnax	184:4133f557d4d4	847	sha1( shaOutput, challenge, strlen(challenge)); // hash the challenge
nixnax	142:54d1543e23e5	848	char encOut[50];
nixnax	184:4133f557d4d4	849	enc64( shaOutput, encOut, 20); // base-64 encode
nixnax	142:54d1543e23e5	850	char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax	142:54d1543e23e5	851	char * version = challenge;
nixnax	184:4133f557d4d4	852	strncpy(version, versionstring,70); // copy their version string
nixnax	142:54d1543e23e5	853	*strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax	142:54d1543e23e5	854	memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax	142:54d1543e23e5	855	n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax	142:54d1543e23e5	856	n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax	142:54d1543e23e5	857	n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax	142:54d1543e23e5	858	n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax	142:54d1543e23e5	859	n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax	142:54d1543e23e5	860	n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax	142:54d1543e23e5	861	n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax	142:54d1543e23e5	862	}
nixnax	142:54d1543e23e5	863	return n; // this response should satisfy a web browser's websocket protocol request
nixnax	142:54d1543e23e5	864	}
nixnax	142:54d1543e23e5	865
nixnax	142:54d1543e23e5	866	#define TCP_FLAG_ACK (1<<4)
nixnax	142:54d1543e23e5	867	#define TCP_FLAG_SYN (1<<1)
nixnax	142:54d1543e23e5	868	#define TCP_FLAG_PSH (1<<3)
nixnax	142:54d1543e23e5	869	#define TCP_FLAG_RST (1<<2)
nixnax	142:54d1543e23e5	870	#define TCP_FLAG_FIN (1<<0)
nixnax	142:54d1543e23e5	871
nixnax	142:54d1543e23e5	872	/// respond to an HTTP request
nixnax	185:4cd8f91e9d49	873	int httpResponse(char * dataStart, int * flags)
nixnax	142:54d1543e23e5	874	{
nixnax	142:54d1543e23e5	875	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	876	n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax	160:bd701ad564cb	877	if (n>0) return n; // if n>0 we already have a response, so return
nixnax	142:54d1543e23e5	878
nixnax	142:54d1543e23e5	879	int nHeader; // byte size of HTTP header
nixnax	142:54d1543e23e5	880	int contentLengthStart; // index where HTML starts
nixnax	142:54d1543e23e5	881	int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax	185:4cd8f91e9d49	882	*flags = TCP_FLAG_ACK \| TCP_FLAG_FIN; // the default case is that we close the connection
nixnax	142:54d1543e23e5	883
nixnax	142:54d1543e23e5	884	httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax	142:54d1543e23e5	885	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	886	httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	887	httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax	142:54d1543e23e5	888	// for example, you could try this using netcat (nc): echo "GET /x" \| nc 172.10.10.2
nixnax	210:a2a651249a9a	889	if( (httpGetRoot==0) \|\| (httpGetx==0) \|\| (httpGet5 == 'w') ) {
nixnax	142:54d1543e23e5	890	n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax	142:54d1543e23e5	891	} else {
nixnax	142:54d1543e23e5	892	n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax	142:54d1543e23e5	893	}
nixnax	142:54d1543e23e5	894	n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax	142:54d1543e23e5	895	contentLengthStart = n; // remember where Content-Length is in buffer
nixnax	142:54d1543e23e5	896	n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax	142:54d1543e23e5	897	n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax	214:4d832a4877ed	898	#define SHOWMAXBUFLEVEL_NO
nixnax	209:aa514cd631ee	899	#ifdef SHOWMAXBUFLEVEL_YES
nixnax	209:aa514cd631ee	900	// 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	901	n=n+sprintf(n+dataStart,"Maxbuflevel: %d\r\n", ppp.rx.maxbuflevel);
nixnax	210:a2a651249a9a	902	#endif
nixnax	142:54d1543e23e5	903	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	904	nHeader=n; // size of HTTP header
nixnax	210:a2a651249a9a	905
nixnax	142:54d1543e23e5	906	if( httpGetRoot == 0 ) {
nixnax	142:54d1543e23e5	907	// this is where we insert our web page into the buffer
nixnax	142:54d1543e23e5	908	memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax	142:54d1543e23e5	909	n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax	185:4cd8f91e9d49	910
nixnax	210:a2a651249a9a	911	} else if ( httpGet5 == 'w' ) { // "w" is a special page for websocket demo
nixnax	142:54d1543e23e5	912	memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax	142:54d1543e23e5	913	n = n + sizeof(webSocketPage)-1; // one less than size
nixnax	185:4cd8f91e9d49	914	*flags = TCP_FLAG_ACK \| TCP_FLAG_PSH; // for a websocket page we do NOT close the connection
nixnax	142:54d1543e23e5	915	} else {
nixnax	142:54d1543e23e5	916	if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax	142:54d1543e23e5	917	#define W3C_COMPLIANT_RESPONSE_NO
nixnax	142:54d1543e23e5	918	// change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax	142:54d1543e23e5	919	#ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax	142:54d1543e23e5	920	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax	146:a45f49a2b29c	921	n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax	142:54d1543e23e5	922	#else
nixnax	142:54d1543e23e5	923	if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax	167:ff8a2d8beeb1	924	n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax	142:54d1543e23e5	925	}
nixnax	142:54d1543e23e5	926	// /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax	146:a45f49a2b29c	927	n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax	142:54d1543e23e5	928	#endif
nixnax	142:54d1543e23e5	929	} else {
nixnax	142:54d1543e23e5	930	// all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax	142:54d1543e23e5	931	n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax	142:54d1543e23e5	932	n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax	142:54d1543e23e5	933	}
nixnax	142:54d1543e23e5	934	}
nixnax	142:54d1543e23e5	935	#define CONTENTLENGTHSIZE 5
nixnax	142:54d1543e23e5	936	char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax	142:54d1543e23e5	937	snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax	142:54d1543e23e5	938	memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax	142:54d1543e23e5	939	return n; // total byte size of our response
nixnax	142:54d1543e23e5	940	}
nixnax	142:54d1543e23e5	941
nixnax	160:bd701ad564cb	942	/// Handle TCP data that is not an HTTP GET.
nixnax	160:bd701ad564cb	943	/// This is handy when for example you want to use netcat (nc.exe) to talk to PPP-Blinky.
nixnax	160:bd701ad564cb	944	/// This could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax	142:54d1543e23e5	945	int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax	142:54d1543e23e5	946	{
nixnax	142:54d1543e23e5	947	int n=0; // number of bytes we have printed so far
nixnax	142:54d1543e23e5	948	if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax	160:bd701ad564cb	949	char mask [4];
nixnax	160:bd701ad564cb	950	memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax	160:bd701ad564cb	951	int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax	160:bd701ad564cb	952	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	953	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	954	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	955	memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax	160:bd701ad564cb	956	n = len; // our response size remains exactly the same length as what we received
nixnax	142:54d1543e23e5	957	} else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax	142:54d1543e23e5	958	n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax	142:54d1543e23e5	959	dataStart[1]=0; // we don't have mask bytes on
nixnax	160:bd701ad564cb	960	} else {
nixnax	184:4133f557d4d4	961	if ( len > 1 ) { // we assume a length of 1 is a keep-alive or push packet
nixnax	184:4133f557d4d4	962	if (v1) putsWhileCheckingInput("TCP data received\n"); // all other tcp push packets
nixnax	184:4133f557d4d4	963	}
nixnax	163:d1b4328e9f08	964	}
nixnax	142:54d1543e23e5	965	return n; // total byte size of our response
nixnax	142:54d1543e23e5	966	}
nixnax	142:54d1543e23e5	967
nixnax	173:6774a0c851c4	968	/// dump the TCP data to the debug serial port
nixnax	173:6774a0c851c4	969	void dumpDataTCP(int outGoing)
nixnax	173:6774a0c851c4	970	{
nixnax	173:6774a0c851c4	971	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	173:6774a0c851c4	972	if (v2) {
nixnax	173:6774a0c851c4	973	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	173:6774a0c851c4	974	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	975	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax	173:6774a0c851c4	976	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	977	ppp.tcpData = ppp.tcpStart + headerSizeTcp; // start of tcp data
nixnax	173:6774a0c851c4	978	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	173:6774a0c851c4	979	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	173:6774a0c851c4	980	char pbuf[80]; // local print buffer
nixnax	173:6774a0c851c4	981	int n=0;
nixnax	210:a2a651249a9a	982
nixnax	173:6774a0c851c4	983	n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax	210:a2a651249a9a	984
nixnax	173:6774a0c851c4	985	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	986	if (n>70) putsWhileCheckingInput("n>pbuf overflow in dumpDataTCP()\n");
nixnax	210:a2a651249a9a	987
nixnax	173:6774a0c851c4	988	putsWhileCheckingInput( pbuf );
nixnax	173:6774a0c851c4	989	if (tcpDataSize > 0) {
nixnax	173:6774a0c851c4	990	ppp.tcpData[tcpDataSize]=0; // insert a null after the data so debug printf stops printing after the data
nixnax	173:6774a0c851c4	991	putsWhileCheckingInput( ppp.tcpData ); // print the tcp payload data
nixnax	173:6774a0c851c4	992	putsWhileCheckingInput("\n");
nixnax	173:6774a0c851c4	993	}
nixnax	173:6774a0c851c4	994	putsWhileCheckingInput( "\x1b[30m" ); // VT100 color code, print black
nixnax	173:6774a0c851c4	995	}
nixnax	173:6774a0c851c4	996	#endif
nixnax	173:6774a0c851c4	997	}
nixnax	173:6774a0c851c4	998
nixnax	142:54d1543e23e5	999	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1000	/// 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	1001	void tcpHandler()
nixnax	142:54d1543e23e5	1002	{
nixnax	154:18b2bd92f557	1003	int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax	154:18b2bd92f557	1004	int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax	173:6774a0c851c4	1005	ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate TCP header start
nixnax	154:18b2bd92f557	1006	int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax	154:18b2bd92f557	1007	int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax	173:6774a0c851c4	1008	char * tcpDataIn = ppp.tcpStart + headerSizeTcp; // start of data TCP data after TCP header
nixnax	154:18b2bd92f557	1009	int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax	154:18b2bd92f557	1010
nixnax	154:18b2bd92f557	1011	unsigned int seq_in = __REV(ppp.tcp->seqTcpR);
nixnax	154:18b2bd92f557	1012	unsigned int ack_in = __REV(ppp.tcp->ackTcpR);
nixnax	142:54d1543e23e5	1013	unsigned int ack_out = seq_in + tcpDataSize;
nixnax	142:54d1543e23e5	1014	unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax	142:54d1543e23e5	1015
nixnax	142:54d1543e23e5	1016	// first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax	173:6774a0c851c4	1017	headerSizeIp=20;
nixnax	173:6774a0c851c4	1018	ppp.ip->headerLength = headerSizeIp/4; // ip header is 20 bytes long
nixnax	173:6774a0c851c4	1019	ppp.ip->lengthR = __REV(40); // 20 ip header + 20 tcp header
nixnax	173:6774a0c851c4	1020	//tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax	154:18b2bd92f557	1021	headerSizeTcp = 20; // shorten outgoing TCP header size 20 bytes
nixnax	173:6774a0c851c4	1022	ppp.tcpStart = ppp.ipStart + headerSizeIp; // recalc TCP header start
nixnax	154:18b2bd92f557	1023	ppp.tcp->offset = (headerSizeTcp/4);
nixnax	173:6774a0c851c4	1024	char * tcpDataOut = ppp.tcpStart + headerSizeTcp; // start of outgoing data
nixnax	142:54d1543e23e5	1025
nixnax	142:54d1543e23e5	1026	int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax	142:54d1543e23e5	1027	int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax	160:bd701ad564cb	1028
nixnax	185:4cd8f91e9d49	1029	ppp.tcp->windowR = __REV16( 1200 ); // set tcp window size to 1200 bytes
nixnax	142:54d1543e23e5	1030
nixnax	142:54d1543e23e5	1031	// A sparse TCP flag interpreter that implements stateless TCP connections
nixnax	142:54d1543e23e5	1032
nixnax	156:163c23249731	1033	switch ( ppp.tcp->flag.All ) {
nixnax	142:54d1543e23e5	1034	case TCP_FLAG_SYN:
nixnax	142:54d1543e23e5	1035	flagsOut = TCP_FLAG_SYN \| TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax	142:54d1543e23e5	1036	seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax	142:54d1543e23e5	1037	ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1038	break;
nixnax	184:4133f557d4d4	1039	case TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1040	case TCP_FLAG_ACK \| TCP_FLAG_PSH:
nixnax	184:4133f557d4d4	1041	if ( (ppp.tcp->flag.All == TCP_FLAG_ACK) && (tcpDataSize == 0)) return; // handle zero-size ack messages by ignoring them
nixnax	142:54d1543e23e5	1042	if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax	179:ba2b2ddd0da5	1043	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // we have data, set the PSH flag
nixnax	185:4cd8f91e9d49	1044	dataLen = httpResponse(tcpDataOut, &flagsOut); // send an http response
nixnax	142:54d1543e23e5	1045	} else {
nixnax	158:841592aed956	1046	dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax	179:ba2b2ddd0da5	1047	if (dataLen > 0) flagsOut = TCP_FLAG_ACK \| TCP_FLAG_PSH; // if we have any data set the PSH flag
nixnax	142:54d1543e23e5	1048	}
nixnax	142:54d1543e23e5	1049	break;
nixnax	142:54d1543e23e5	1050	case TCP_FLAG_FIN:
nixnax	142:54d1543e23e5	1051	case TCP_FLAG_FIN \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1052	case TCP_FLAG_FIN \| TCP_FLAG_PSH \| TCP_FLAG_ACK:
nixnax	142:54d1543e23e5	1053	flagsOut = TCP_FLAG_ACK \| TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax	142:54d1543e23e5	1054	ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax	142:54d1543e23e5	1055	break;
nixnax	142:54d1543e23e5	1056	default:
nixnax	179:ba2b2ddd0da5	1057	return; // ignore all other packets
nixnax	142:54d1543e23e5	1058	} // switch
nixnax	142:54d1543e23e5	1059
nixnax	142:54d1543e23e5	1060	// The TCP flag handling is now done
nixnax	142:54d1543e23e5	1061	// first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax	147:0f40005cbc5f	1062	swapIpAddresses(); // swap IP source and destination addresses
nixnax	149:969d98f6fb88	1063	swapIpPorts(); // swap IP source and destination ports
nixnax	142:54d1543e23e5	1064
nixnax	158:841592aed956	1065	ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	158:841592aed956	1066	ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax	160:bd701ad564cb	1067
nixnax	156:163c23249731	1068	ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax	142:54d1543e23e5	1069
nixnax	159:4d1bf96a59cd	1070	// recalculate all the header sizes
nixnax	154:18b2bd92f557	1071	tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax	154:18b2bd92f557	1072	int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax	159:4d1bf96a59cd	1073	ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax	142:54d1543e23e5	1074	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	1075
nixnax	142:54d1543e23e5	1076	// the header is all set up, now do the IP and TCP checksums
nixnax	146:a45f49a2b29c	1077	IpHeaderCheckSum(); // calculate new IP header checksum
nixnax	170:3d3b2126181c	1078	checkSumPseudoHeader( tcpSize ); // get the TCP pseudo-header checksum
nixnax	159:4d1bf96a59cd	1079	ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax	161:d59f778bc8ab	1080	unsigned int pseudoHeaderSum=dataCheckSum(ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax	159:4d1bf96a59cd	1081	ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax	160:bd701ad564cb	1082
nixnax	170:3d3b2126181c	1083	dumpHeaderIP(1); // dump outgoing IP header before sending the frame
nixnax	170:3d3b2126181c	1084	dumpHeaderTCP(1); // dump outgoing TCP header before sending the frame
nixnax	173:6774a0c851c4	1085	dumpDataTCP(1); // dump outgoing TCP data before sending the frame
nixnax	182:f039ec218c9f	1086	if (0) wait_ms(45); // 45 ms delay before sending frame - a typical internet delay time
nixnax	144:01d98cf7738e	1087	sendPppFrame(); // All preparation complete - send the TCP response
nixnax	142:54d1543e23e5	1088	if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax	142:54d1543e23e5	1089	memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax	142:54d1543e23e5	1090	}
nixnax	142:54d1543e23e5	1091
nixnax	142:54d1543e23e5	1092	/// handle an incoming TCP packet
nixnax	142:54d1543e23e5	1093	void TCPpacket()
nixnax	142:54d1543e23e5	1094	{
nixnax	173:6774a0c851c4	1095	dumpHeaderIP(0); // dump incoming packet IP header
nixnax	173:6774a0c851c4	1096	dumpHeaderTCP(0); // dump incoming packet TCP header
nixnax	173:6774a0c851c4	1097	dumpDataTCP(0); // dump incoming packet data
nixnax	142:54d1543e23e5	1098	tcpHandler();
nixnax	142:54d1543e23e5	1099	}
nixnax	142:54d1543e23e5	1100
nixnax	142:54d1543e23e5	1101	/// handle the remaining IP protocols by ignoring them
nixnax	142:54d1543e23e5	1102	void otherProtocol()
nixnax	142:54d1543e23e5	1103	{
nixnax	142:54d1543e23e5	1104	debugPrintf("Other IP protocol");
nixnax	142:54d1543e23e5	1105	}
nixnax	142:54d1543e23e5	1106
nixnax	142:54d1543e23e5	1107	/// process an incoming IP packet
nixnax	142:54d1543e23e5	1108	void IPframe()
nixnax	142:54d1543e23e5	1109	{
nixnax	167:ff8a2d8beeb1	1110	int protocol = ppp.ip->protocol;
nixnax	142:54d1543e23e5	1111	switch (protocol) {
nixnax	142:54d1543e23e5	1112	case 1:
nixnax	142:54d1543e23e5	1113	ICMPpacket();
nixnax	142:54d1543e23e5	1114	break;
nixnax	142:54d1543e23e5	1115	case 2:
nixnax	142:54d1543e23e5	1116	IGMPpacket();
nixnax	142:54d1543e23e5	1117	break;
nixnax	142:54d1543e23e5	1118	case 17:
nixnax	142:54d1543e23e5	1119	UDPpacket();
nixnax	142:54d1543e23e5	1120	break;
nixnax	142:54d1543e23e5	1121	case 6:
nixnax	142:54d1543e23e5	1122	TCPpacket();
nixnax	142:54d1543e23e5	1123	break;
nixnax	142:54d1543e23e5	1124	default:
nixnax	142:54d1543e23e5	1125	otherProtocol();
nixnax	142:54d1543e23e5	1126	}
nixnax	142:54d1543e23e5	1127	}
nixnax	142:54d1543e23e5	1128
nixnax	142:54d1543e23e5	1129	/// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax	142:54d1543e23e5	1130	void LCPconfReq()
nixnax	142:54d1543e23e5	1131	{
nixnax	142:54d1543e23e5	1132	debugPrintf("LCP Config ");
nixnax	175:b4e6f8a6fe00	1133	if ( ppp.lcp->lengthR != __REV16(4) ) {
nixnax	175:b4e6f8a6fe00	1134	ppp.lcp->code=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax	142:54d1543e23e5	1135	debugPrintf("Reject\n");
nixnax	144:01d98cf7738e	1136	sendPppFrame();
nixnax	142:54d1543e23e5	1137	} else {
nixnax	175:b4e6f8a6fe00	1138	ppp.lcp->code=2; // ack zero conf
nixnax	142:54d1543e23e5	1139	debugPrintf("Ack\n");
nixnax	144:01d98cf7738e	1140	sendPppFrame();
nixnax	142:54d1543e23e5	1141	debugPrintf("LCP Ask\n");
nixnax	175:b4e6f8a6fe00	1142	ppp.lcp->code=1; // request no options
nixnax	144:01d98cf7738e	1143	sendPppFrame();
nixnax	142:54d1543e23e5	1144	}
nixnax	142:54d1543e23e5	1145	}
nixnax	142:54d1543e23e5	1146
nixnax	142:54d1543e23e5	1147	/// handle LCP acknowledge packets by ignoring them
nixnax	142:54d1543e23e5	1148	void LCPconfAck()
nixnax	142:54d1543e23e5	1149	{
nixnax	142:54d1543e23e5	1150	debugPrintf("LCP Ack\n");
nixnax	142:54d1543e23e5	1151	}
nixnax	142:54d1543e23e5	1152
nixnax	143:c5019f856a56	1153	/// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax	142:54d1543e23e5	1154	void LCPend()
nixnax	142:54d1543e23e5	1155	{
nixnax	175:b4e6f8a6fe00	1156	ppp.lcp->code=6; // end
nixnax	144:01d98cf7738e	1157	sendPppFrame(); // acknowledge
nixnax	142:54d1543e23e5	1158	ppp.online=0; // start hunting for connect string again
nixnax	142:54d1543e23e5	1159	pppInitStruct(); // flush the receive buffer
nixnax	143:c5019f856a56	1160	debugPrintf("LCP End (Disconnect from host)\n");
nixnax	142:54d1543e23e5	1161	}
nixnax	142:54d1543e23e5	1162
nixnax	142:54d1543e23e5	1163	/// respond to other LCP requests by ignoring them
nixnax	142:54d1543e23e5	1164	void LCPother()
nixnax	142:54d1543e23e5	1165	{
nixnax	142:54d1543e23e5	1166	debugPrintf("LCP Other\n");
nixnax	142:54d1543e23e5	1167	dumpPPPFrame();
nixnax	142:54d1543e23e5	1168	}
nixnax	142:54d1543e23e5	1169
nixnax	142:54d1543e23e5	1170	/// process incoming LCP packets
nixnax	142:54d1543e23e5	1171	void LCPframe()
nixnax	142:54d1543e23e5	1172	{
nixnax	175:b4e6f8a6fe00	1173	int code = ppp.lcp->code;
nixnax	142:54d1543e23e5	1174	switch (code) {
nixnax	142:54d1543e23e5	1175	case 1:
nixnax	142:54d1543e23e5	1176	LCPconfReq();
nixnax	142:54d1543e23e5	1177	break; // config request
nixnax	142:54d1543e23e5	1178	case 2:
nixnax	142:54d1543e23e5	1179	LCPconfAck();
nixnax	142:54d1543e23e5	1180	break; // config ack
nixnax	142:54d1543e23e5	1181	case 5:
nixnax	142:54d1543e23e5	1182	LCPend();
nixnax	142:54d1543e23e5	1183	break; // end connection
nixnax	142:54d1543e23e5	1184	default:
nixnax	142:54d1543e23e5	1185	LCPother();
nixnax	142:54d1543e23e5	1186	}
nixnax	142:54d1543e23e5	1187	}
nixnax	142:54d1543e23e5	1188
nixnax	142:54d1543e23e5	1189	/// discard packets that are not IP, IPCP, or LCP
nixnax	142:54d1543e23e5	1190	void discardedFrame()
nixnax	142:54d1543e23e5	1191	{
nixnax	142:54d1543e23e5	1192	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	1193	}
nixnax	142:54d1543e23e5	1194
nixnax	142:54d1543e23e5	1195	/// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax	142:54d1543e23e5	1196	void determinePacketType()
nixnax	142:54d1543e23e5	1197	{
nixnax	167:ff8a2d8beeb1	1198	if ( ppp.ppp->address != 0xff ) {
nixnax	167:ff8a2d8beeb1	1199	debugPrintf("Unexpected: PPP address != ff\n");
nixnax	142:54d1543e23e5	1200	return;
nixnax	142:54d1543e23e5	1201	}
nixnax	167:ff8a2d8beeb1	1202	if ( ppp.ppp->control != 3 ) {
nixnax	167:ff8a2d8beeb1	1203	debugPrintf("Unexpected: PPP control != 3\n");
nixnax	142:54d1543e23e5	1204	return;
nixnax	142:54d1543e23e5	1205	}
nixnax	167:ff8a2d8beeb1	1206	unsigned int protocol = __REV16( ppp.ppp->protocolR );
nixnax	167:ff8a2d8beeb1	1207	switch ( protocol ) {
nixnax	167:ff8a2d8beeb1	1208	case 0xc021:
nixnax	142:54d1543e23e5	1209	LCPframe();
nixnax	142:54d1543e23e5	1210	break; // link control
nixnax	167:ff8a2d8beeb1	1211	case 0x8021:
nixnax	142:54d1543e23e5	1212	IPCPframe();
nixnax	142:54d1543e23e5	1213	break; // IP control
nixnax	167:ff8a2d8beeb1	1214	case 0x0021:
nixnax	142:54d1543e23e5	1215	IPframe();
nixnax	142:54d1543e23e5	1216	break; // IP itself
nixnax	142:54d1543e23e5	1217	default:
nixnax	142:54d1543e23e5	1218	discardedFrame();
nixnax	142:54d1543e23e5	1219	}
nixnax	142:54d1543e23e5	1220	}
nixnax	142:54d1543e23e5	1221
nixnax	146:a45f49a2b29c	1222	/// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax	146:a45f49a2b29c	1223	void sniff()
nixnax	146:a45f49a2b29c	1224	{
nixnax	146:a45f49a2b29c	1225	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	1226	}
nixnax	146:a45f49a2b29c	1227
nixnax	142:54d1543e23e5	1228	/// scan the PPP serial input stream for frame start markers
nixnax	143:c5019f856a56	1229	void waitForPppFrame()
nixnax	142:54d1543e23e5	1230	{
nixnax	142:54d1543e23e5	1231	while(1) {
nixnax	142:54d1543e23e5	1232	if ( ppp.rx.head != ppp.rx.tail ) {
nixnax	142:54d1543e23e5	1233	int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax	142:54d1543e23e5	1234	int rx = pc_getBuf(); // get the character
nixnax	142:54d1543e23e5	1235	if (rx==FRAME_7E) {
nixnax	142:54d1543e23e5	1236	if (ppp.firstFrame) { // is this the start of the first frame start
nixnax	142:54d1543e23e5	1237	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1238	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax	181:bcfe7fe2142d	1239	ppp.firstFrame=0; // clear first frame flag
nixnax	142:54d1543e23e5	1240	} else {
nixnax	142:54d1543e23e5	1241	ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax	142:54d1543e23e5	1242	processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax	142:54d1543e23e5	1243	ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax	142:54d1543e23e5	1244	ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax	142:54d1543e23e5	1245	break;
nixnax	142:54d1543e23e5	1246	}
nixnax	142:54d1543e23e5	1247	}
nixnax	142:54d1543e23e5	1248	}
nixnax	210:a2a651249a9a	1249	// change below to YES to enable the serial to UDP demo
nixnax	210:a2a651249a9a	1250	#define SERIAL_TO_UDP_NO
nixnax	210:a2a651249a9a	1251	#ifdef SERIAL_TO_UDP_YES
nixnax	210:a2a651249a9a	1252	sendUdpData(); // demo that sends characters received on the DEBUG serial port via UDP to another host
nixnax	210:a2a651249a9a	1253	#endif
nixnax	142:54d1543e23e5	1254	}
nixnax	142:54d1543e23e5	1255	}
nixnax	142:54d1543e23e5	1256
nixnax	209:aa514cd631ee	1257	/// 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	1258	// 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	1259	void waitForPcConnectString()
nixnax	142:54d1543e23e5	1260	{
nixnax	142:54d1543e23e5	1261	while(ppp.online == 0) {
nixnax	142:54d1543e23e5	1262	// search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax	142:54d1543e23e5	1263	char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax	142:54d1543e23e5	1264	if (found1 != NULL) {
nixnax	209:aa514cd631ee	1265	if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax	208:73086736610a	1266	// respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax	142:54d1543e23e5	1267	pc.puts("CLIENTSERVER");
nixnax	142:54d1543e23e5	1268	ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax	142:54d1543e23e5	1269	}
nixnax	142:54d1543e23e5	1270	}
nixnax	142:54d1543e23e5	1271	}
nixnax	142:54d1543e23e5	1272
nixnax	144:01d98cf7738e	1273	/// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax	144:01d98cf7738e	1274	void initializePpp()
nixnax	142:54d1543e23e5	1275	{
nixnax	210:a2a651249a9a	1276	#ifdef SERIAL_PORT_MONITOR_YES
nixnax	144:01d98cf7738e	1277	debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax	184:4133f557d4d4	1278	debugPrintf("\x1b[2J\x1b[H\x1b[30m");
nixnax	184:4133f557d4d4	1279	wait_ms(200); // a brief wait so a human can see the reset event
nixnax	184:4133f557d4d4	1280	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	1281	#endif
nixnax	179:ba2b2ddd0da5	1282	pppInitStruct(); // initialize all the variables/properties/buffers
nixnax	179:ba2b2ddd0da5	1283	pc.baud(115200); // pc serial port acting as a dial-up modem - for PPP traffic
nixnax	179:ba2b2ddd0da5	1284	pc.attach(&pppReceiveHandler, RawSerial::RxIrq); // set up serial port receive interrupt handler
nixnax	143:c5019f856a56	1285	}

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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.