Nicolas Nackel / Mbed 2 deprecated PPP-Blinky

Small Internet Protocol Stack using a standard serial port.

Dependencies:   mbed

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@159:4d1bf96a59cd, 2017-09-02 (annotated)

Committer:
nixnax
Date:
Sat Sep 02 07:48:53 2017 +0000
Revision:
159:4d1bf96a59cd
Parent:
158:841592aed956
Child:
160:bd701ad564cb
Better pseudo header.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 142:54d1543e23e5 1 // PPP-Blinky - "The Most Basic Internet Of a Thing"
nixnax 142:54d1543e23e5 2 // A Tiny HTTP Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax 142:54d1543e23e5 3 // Receives UDP packets and responds to ping (ICMP Echo requests)
nixnax 142:54d1543e23e5 4 // WebSocket Service - see https://en.wikipedia.org/wiki/WebSocket
nixnax 142:54d1543e23e5 5
nixnax 142:54d1543e23e5 6 // Copyright 2016/2017 Nicolas Nackel aka Nixnax. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nixnax 142:54d1543e23e5 7
nixnax 142:54d1543e23e5 8 // Notes and Instructions
nixnax 142:54d1543e23e5 9 // http://bit.ly/PPP-Blinky-Instructions
nixnax 142:54d1543e23e5 10 // http://bit.ly/win-rasdial-config
nixnax 142:54d1543e23e5 11
nixnax 142:54d1543e23e5 12 // Handy reading material
nixnax 142:54d1543e23e5 13 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 142:54d1543e23e5 14 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 142:54d1543e23e5 15 // http://atari.kensclassics.org/wcomlog.htm
nixnax 142:54d1543e23e5 16
nixnax 142:54d1543e23e5 17 // Handy tools
nixnax 142:54d1543e23e5 18 // https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax 142:54d1543e23e5 19 // https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax 142:54d1543e23e5 20 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 142:54d1543e23e5 21 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax 142:54d1543e23e5 22 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 142:54d1543e23e5 23 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 142:54d1543e23e5 24 // Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax 142:54d1543e23e5 25
nixnax 142:54d1543e23e5 26 // Connecting PPP-Blinky to Linux
nixnax 142:54d1543e23e5 27 // PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax 142:54d1543e23e5 28 // pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax 142:54d1543e23e5 29 // in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax 142:54d1543e23e5 30 // See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax 142:54d1543e23e5 31
nixnax 142:54d1543e23e5 32 // Special pages when PPP-Blinky is running
nixnax 142:54d1543e23e5 33 // 172.10.10.2 root page
nixnax 143:c5019f856a56 34 // 172.10.10.2/x returns a number that increments every time you request a page - this is handy for testing
nixnax 146:a45f49a2b29c 35 // 172.10.10.2/xb also returns a number, but issues a fast refresh meta command. This allows you to use your browser to benchmark page load speed
nixnax 142:54d1543e23e5 36 // 172.10.10.2/ws a simple WebSocket demo
nixnax 142:54d1543e23e5 37 // http://jsfiddle.net/d26cyuh2/ more complete WebSocket demo in JSFiddle
nixnax 142:54d1543e23e5 38
nixnax 142:54d1543e23e5 39 // Ok, enough talking, time to check out some code!!
nixnax 142:54d1543e23e5 40
nixnax 142:54d1543e23e5 41 #include "ppp-blinky.h"
nixnax 142:54d1543e23e5 42
nixnax 142:54d1543e23e5 43 // The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax 146:a45f49a2b29c 44 // Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor the debug output.
nixnax 142:54d1543e23e5 45 // Using the second serial port will slow down packet response time
nixnax 142:54d1543e23e5 46 // Note - the LPC11U24 does NOT have a second serial port
nixnax 146:a45f49a2b29c 47
nixnax 157:3a3530d60e96 48 #define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax 142:54d1543e23e5 49
nixnax 142:54d1543e23e5 50 // here we define the OPTIONAL, second debug serial port for various mbed target boards
nixnax 142:54d1543e23e5 51 #ifdef SERIAL_PORT_MONITOR_YES
nixnax 142:54d1543e23e5 52 #if defined(TARGET_LPC1768)
nixnax 142:54d1543e23e5 53 Serial xx(p9, p10); // Second serial port on LPC1768 - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax 142:54d1543e23e5 54 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE) || defined(TARGET_NUCLEO_L053R8) || defined(TARGET_NUCLEO_L476RG) || defined(TARGET_NUCLEO_F401RE)
nixnax 142:54d1543e23e5 55 Serial xx(PC_10, PC_11); // Second serial port on NUCLEO boards - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax 142:54d1543e23e5 56 #elif defined(TARGET_LPC11U24)
nixnax 142:54d1543e23e5 57 #error The LPC11U24 does not have a second serial port to use for debugging - change SERIAL_PORT_MONITOR_YES back to SERIAL_PORT_MONITOR_NO
nixnax 142:54d1543e23e5 58 #elif defined (TARGET_KL46Z) || (TARGET_KL25Z)
nixnax 142:54d1543e23e5 59 Serial xx(PTE0,PTE1); // Second serial port on FRDM-KL46Z board
nixnax 142:54d1543e23e5 60 #elif defined(YOUR_TARGET_BOARD_NAME_HERE)
nixnax 142:54d1543e23e5 61 // change the next line to YOUR target board's second serial port pin definition if it's not present - and if it works, please send it to me - thanks!!!
nixnax 142:54d1543e23e5 62 Serial xx(p9, p10); // change this to YOUR board second serial port pin definition - and please send it to me if it works!!!
nixnax 142:54d1543e23e5 63 #else
nixnax 142:54d1543e23e5 64 #error Add your target board's second serial port here if you want to use debugging - or simply change SERIAL_PORT_MONITOR_YES to SERIAL_PORT_MONITOR_NO
nixnax 142:54d1543e23e5 65 #endif
nixnax 142:54d1543e23e5 66 #define debugPrintf(x...) xx.printf (x) /* if we have a serial port we print debug messages */
nixnax 142:54d1543e23e5 67 #define debugPutc(x...) xx.putc(x)
nixnax 142:54d1543e23e5 68 #define debugBaudRate(x...) xx.baud(x)
nixnax 142:54d1543e23e5 69 #else
nixnax 142:54d1543e23e5 70 // if we don't have a debug port the debug print functions do nothing
nixnax 142:54d1543e23e5 71 #define debugPrintf(x...) {}
nixnax 142:54d1543e23e5 72 #define debugPutc(x...) {}
nixnax 142:54d1543e23e5 73 #define debugBaudRate(x...) {}
nixnax 142:54d1543e23e5 74 #endif
nixnax 142:54d1543e23e5 75
nixnax 142:54d1543e23e5 76 // verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax 142:54d1543e23e5 77 #define v0 1
nixnax 142:54d1543e23e5 78 #define v1 0
nixnax 142:54d1543e23e5 79 #define v2 0
nixnax 142:54d1543e23e5 80 #define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax 142:54d1543e23e5 81 #define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax 142:54d1543e23e5 82
nixnax 142:54d1543e23e5 83 // this is the webpage we serve when we get an HTTP request to root (/)
nixnax 142:54d1543e23e5 84 // keep size under ~900 bytes to fit into a single PPP packet
nixnax 142:54d1543e23e5 85
nixnax 142:54d1543e23e5 86 const static char rootWebPage[] = "\
nixnax 142:54d1543e23e5 87 <!DOCTYPE html>\
nixnax 142:54d1543e23e5 88 <html>\
nixnax 142:54d1543e23e5 89 <head>\
nixnax 146:a45f49a2b29c 90 <title>mbed PPP-Blinky</title>\r\n\
nixnax 146:a45f49a2b29c 91 <script>\r\n\
nixnax 142:54d1543e23e5 92 window.onload=function(){\
nixnax 142:54d1543e23e5 93 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 146:a45f49a2b29c 94 x().textContent=parseInt(x().textContent)+1;},100);};\r\n\
nixnax 146:a45f49a2b29c 95 </script>\r\n\
nixnax 142:54d1543e23e5 96 </head>\
nixnax 142:54d1543e23e5 97 <body style=\"font-family: sans-serif; font-size:20px; text-align:center; color:#807070\">\
nixnax 142:54d1543e23e5 98 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 142:54d1543e23e5 99 <h1 id=\"w\">0</h1>\
nixnax 142:54d1543e23e5 100 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 142:54d1543e23e5 101 <h1><a href=\"/ws\">WebSocket Demo</a></h1>\
nixnax 142:54d1543e23e5 102 <h1><a href=\"/x\">Benchmark 1</a></h1>\
nixnax 142:54d1543e23e5 103 <h1><a href=\"/xb\">Benchmark 2</a></h1>\
nixnax 142:54d1543e23e5 104 <h1><a href=\"http://jsfiddle.net/d26cyuh2/\">JSFiddle Demo</a></h1>\
nixnax 142:54d1543e23e5 105 </body>\
nixnax 146:a45f49a2b29c 106 </html>\r\n"; // size = 644 bytes plus 1 null byte = 645 bytes
nixnax 142:54d1543e23e5 107
nixnax 150:3366bf3d294e 108 // this is websocket demo 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 142:54d1543e23e5 151 BufferedSerial pc(USBTX, USBRX, 100); // 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 152:025c73b6c0a9 158
nixnax 142:54d1543e23e5 159 /// a structure to keep all our ppp globals in
nixnax 142:54d1543e23e5 160 struct pppType {
nixnax 154:18b2bd92f557 161 pppHeaderType * ppp; // pointer to ppp struct
nixnax 154:18b2bd92f557 162 union {
nixnax 154:18b2bd92f557 163 ipHeaderType * ip; // pointer to ip header struct
nixnax 155:9c6a1d249e26 164 char * ipStart; // char pointer to ip header struct (need a char pointer for byte offset calculations)
nixnax 154:18b2bd92f557 165 };
nixnax 154:18b2bd92f557 166 union {
nixnax 154:18b2bd92f557 167 tcpHeaderType * tcp; // pointer to tcp header struct
nixnax 155:9c6a1d249e26 168 char * tcpStart; // char pointer to tcp header struct (need a char pointer for byte offset calculations)
nixnax 154:18b2bd92f557 169 };
nixnax 142:54d1543e23e5 170 int online; // we hunt for a PPP connection if this is zero
nixnax 143:c5019f856a56 171 int hostIP; // ip address of host
nixnax 145:098b6ed2f7f2 172 int fcs; // PPP "frame check sequence" - a 16-bit HDLC-like checksum used in all PPP frames
nixnax 142:54d1543e23e5 173 int ledState; // state of LED1
nixnax 146:a45f49a2b29c 174 int responseCounter;
nixnax 142:54d1543e23e5 175 int firstFrame; // cleared after first frame
nixnax 159:4d1bf96a59cd 176 unsigned int sum; // a checksum used in headers
nixnax 142:54d1543e23e5 177 struct {
nixnax 142:54d1543e23e5 178 #define RXBUFLEN (1<<11)
nixnax 142:54d1543e23e5 179 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 2048 bytes)
nixnax 142:54d1543e23e5 180 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 142:54d1543e23e5 181 int head;
nixnax 142:54d1543e23e5 182 int tail;
nixnax 142:54d1543e23e5 183 int rtail;
nixnax 142:54d1543e23e5 184 int buflevel;
nixnax 142:54d1543e23e5 185 } rx; // serial port objects
nixnax 142:54d1543e23e5 186 struct {
nixnax 142:54d1543e23e5 187 int len; // number of bytes in buffer
nixnax 142:54d1543e23e5 188 int crc; // PPP CRC (frame check)
nixnax 152:025c73b6c0a9 189 #define PPP_max_size 1600
nixnax 152:025c73b6c0a9 190 // we are assuming 100 bytes more than MTU size of 1500
nixnax 154:18b2bd92f557 191 char buf[PPP_max_size]; // send and receive buffer large enough for largest IP packet
nixnax 142:54d1543e23e5 192 } pkt; // ppp buffer objects
nixnax 142:54d1543e23e5 193 struct {
nixnax 142:54d1543e23e5 194 int frameStartIndex; // frame start marker
nixnax 142:54d1543e23e5 195 int frameEndIndex; // frame end marker
nixnax 142:54d1543e23e5 196 } hdlc; // hdlc frame objects
nixnax 142:54d1543e23e5 197 struct {
nixnax 142:54d1543e23e5 198 unsigned int ident; // our IP ident value (outgoing frame count)
nixnax 154:18b2bd92f557 199 } ipData; // ip related object
nixnax 142:54d1543e23e5 200 };
nixnax 142:54d1543e23e5 201
nixnax 142:54d1543e23e5 202 pppType ppp; // our global - definitely not thread safe
nixnax 142:54d1543e23e5 203
nixnax 142:54d1543e23e5 204 /// Initialize the ppp structure and clear the receive buffer
nixnax 142:54d1543e23e5 205 void pppInitStruct()
nixnax 142:54d1543e23e5 206 {
nixnax 142:54d1543e23e5 207 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 142:54d1543e23e5 208 ppp.online=0;
nixnax 142:54d1543e23e5 209 ppp.rx.tail=0;
nixnax 142:54d1543e23e5 210 ppp.rx.rtail=0;
nixnax 142:54d1543e23e5 211 ppp.rx.head=0;
nixnax 142:54d1543e23e5 212 ppp.rx.buflevel=0;
nixnax 142:54d1543e23e5 213 ppp.pkt.len=0;
nixnax 154:18b2bd92f557 214 ppp.ipData.ident=10000; // easy to recognize in ip packet dumps
nixnax 142:54d1543e23e5 215 ppp.ledState=0;
nixnax 142:54d1543e23e5 216 ppp.hdlc.frameStartIndex=0;
nixnax 146:a45f49a2b29c 217 ppp.responseCounter=0;
nixnax 142:54d1543e23e5 218 ppp.firstFrame=1;
nixnax 154:18b2bd92f557 219 ppp.ppp = (pppHeaderType *)ppp.pkt.buf;
nixnax 154:18b2bd92f557 220 ppp.ip = (ipHeaderType *)(ppp.pkt.buf+4); // ppp header is 4 bytes long
nixnax 142:54d1543e23e5 221 }
nixnax 142:54d1543e23e5 222
nixnax 142:54d1543e23e5 223 /// Toggle the LED on every second PPP packet received
nixnax 142:54d1543e23e5 224 void led1Toggle()
nixnax 142:54d1543e23e5 225 {
nixnax 142:54d1543e23e5 226 led1 = (ppp.ledState >> 1) & 1; // use second bit, in other words toggle LED only every second packet
nixnax 143:c5019f856a56 227 ppp.ledState++;
nixnax 142:54d1543e23e5 228 }
nixnax 142:54d1543e23e5 229
nixnax 152:025c73b6c0a9 230 /// returns 1 after a connect message, 0 at startup or after a disconnect message
nixnax 150:3366bf3d294e 231 int connectedPpp()
nixnax 142:54d1543e23e5 232 {
nixnax 142:54d1543e23e5 233 return ppp.online;
nixnax 143:c5019f856a56 234 }
nixnax 142:54d1543e23e5 235
nixnax 143:c5019f856a56 236 /// Check for available characters from the PC and read them into our own circular serial receive buffer at ppp.rx.buf.
nixnax 143:c5019f856a56 237 /// Also, if we are offline and a 0x7e frame start character is seen, we go online immediately
nixnax 142:54d1543e23e5 238 void checkPc()
nixnax 142:54d1543e23e5 239 {
nixnax 142:54d1543e23e5 240 char ch;
nixnax 142:54d1543e23e5 241 if ( pc.readable() ) {
nixnax 142:54d1543e23e5 242 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 142:54d1543e23e5 243 if ( hd == ppp.rx.rtail ) {
nixnax 142:54d1543e23e5 244 debugPrintf("\nReceive buffer full\n");
nixnax 142:54d1543e23e5 245 return;
nixnax 142:54d1543e23e5 246 }
nixnax 142:54d1543e23e5 247 ch = pc.getc(); // read new character
nixnax 142:54d1543e23e5 248 ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax 142:54d1543e23e5 249 if ( ppp.online == 0 ) {
nixnax 142:54d1543e23e5 250 if (ch == 0x7E) {
nixnax 142:54d1543e23e5 251 ppp.online = 1;
nixnax 142:54d1543e23e5 252 }
nixnax 142:54d1543e23e5 253 }
nixnax 142:54d1543e23e5 254 ppp.rx.head = hd; // update head pointer
nixnax 142:54d1543e23e5 255 ppp.rx.buflevel++;
nixnax 142:54d1543e23e5 256 }
nixnax 142:54d1543e23e5 257 }
nixnax 142:54d1543e23e5 258
nixnax 142:54d1543e23e5 259 /// print to debug port while checking for incoming characters
nixnax 142:54d1543e23e5 260 void putcWhileCheckingInput( char outByte )
nixnax 142:54d1543e23e5 261 {
nixnax 142:54d1543e23e5 262 #ifdef SERIAL_PORT_MONITOR_YES
nixnax 142:54d1543e23e5 263 checkPc();
nixnax 142:54d1543e23e5 264 debugPutc( outByte );
nixnax 142:54d1543e23e5 265 checkPc();
nixnax 142:54d1543e23e5 266 #endif
nixnax 142:54d1543e23e5 267 }
nixnax 142:54d1543e23e5 268
nixnax 142:54d1543e23e5 269 /// puts to debug port while checking the PPP input stream
nixnax 142:54d1543e23e5 270 void putsWhileCheckingInput( char * data )
nixnax 142:54d1543e23e5 271 {
nixnax 142:54d1543e23e5 272 #ifdef SERIAL_PORT_MONITOR_YES
nixnax 142:54d1543e23e5 273 char * nextChar = data;
nixnax 142:54d1543e23e5 274 while( *nextChar != 0 ) {
nixnax 142:54d1543e23e5 275 putcWhileCheckingInput( *nextChar ); // write one character to debug port while checking input
nixnax 142:54d1543e23e5 276 nextChar++;
nixnax 142:54d1543e23e5 277 }
nixnax 142:54d1543e23e5 278 #endif
nixnax 142:54d1543e23e5 279 }
nixnax 142:54d1543e23e5 280
nixnax 145:098b6ed2f7f2 281 /// Initialize the PPP FCS (frame check sequence) total
nixnax 145:098b6ed2f7f2 282 void fcsReset()
nixnax 142:54d1543e23e5 283 {
nixnax 145:098b6ed2f7f2 284 ppp.fcs=0xffff; // crc restart
nixnax 142:54d1543e23e5 285 }
nixnax 142:54d1543e23e5 286
nixnax 145:098b6ed2f7f2 287 /// update the cumulative PPP FCS (frame check sequence)
nixnax 145:098b6ed2f7f2 288 void fcsDo(int x)
nixnax 142:54d1543e23e5 289 {
nixnax 142:54d1543e23e5 290 for (int i=0; i<8; i++) {
nixnax 145:098b6ed2f7f2 291 ppp.fcs=((ppp.fcs&1)^(x&1))?(ppp.fcs>>1)^0x8408:ppp.fcs>>1; // crc calculator
nixnax 142:54d1543e23e5 292 x>>=1;
nixnax 142:54d1543e23e5 293 }
nixnax 142:54d1543e23e5 294 checkPc(); // handle input
nixnax 142:54d1543e23e5 295 }
nixnax 142:54d1543e23e5 296
nixnax 145:098b6ed2f7f2 297 /// calculate the PPP FCS (frame check sequence) on an entire block of memory
nixnax 145:098b6ed2f7f2 298 int fcsBuf(char * buf, int size) // crc on an entire block of memory
nixnax 142:54d1543e23e5 299 {
nixnax 145:098b6ed2f7f2 300 fcsReset();
nixnax 145:098b6ed2f7f2 301 for(int i=0; i<size; i++)fcsDo(*buf++);
nixnax 145:098b6ed2f7f2 302 return ppp.fcs;
nixnax 142:54d1543e23e5 303 }
nixnax 142:54d1543e23e5 304
nixnax 142:54d1543e23e5 305 /// Get one character from our received PPP buffer
nixnax 142:54d1543e23e5 306 int pc_getBuf()
nixnax 142:54d1543e23e5 307 {
nixnax 142:54d1543e23e5 308 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 142:54d1543e23e5 309 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 142:54d1543e23e5 310 ppp.rx.buflevel--;
nixnax 142:54d1543e23e5 311 return x;
nixnax 142:54d1543e23e5 312 }
nixnax 142:54d1543e23e5 313
nixnax 142:54d1543e23e5 314 /// Dump a PPP frame to the debug serial port
nixnax 142:54d1543e23e5 315 /// Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 142:54d1543e23e5 316 /// Capture the frame's hex output in your terminal program and save as a text file
nixnax 142:54d1543e23e5 317 /// In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 142:54d1543e23e5 318 void dumpPPPFrame()
nixnax 142:54d1543e23e5 319 {
nixnax 142:54d1543e23e5 320 char pbuf[30];
nixnax 142:54d1543e23e5 321 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 142:54d1543e23e5 322 checkPc();
nixnax 142:54d1543e23e5 323 sprintf(pbuf, "%02x ", ppp.pkt.buf[i]);
nixnax 142:54d1543e23e5 324 checkPc();
nixnax 142:54d1543e23e5 325 putsWhileCheckingInput(pbuf);
nixnax 142:54d1543e23e5 326 }
nixnax 142:54d1543e23e5 327 checkPc();
nixnax 142:54d1543e23e5 328 sprintf(pbuf, " CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 142:54d1543e23e5 329 checkPc();
nixnax 142:54d1543e23e5 330 putsWhileCheckingInput(pbuf);
nixnax 142:54d1543e23e5 331 }
nixnax 142:54d1543e23e5 332
nixnax 142:54d1543e23e5 333 /// Process a received PPP frame
nixnax 142:54d1543e23e5 334 void processPPPFrame(int start, int end)
nixnax 142:54d1543e23e5 335 {
nixnax 142:54d1543e23e5 336 led1Toggle(); // change led1 state on every frame we receive
nixnax 142:54d1543e23e5 337 if(start==end) {
nixnax 142:54d1543e23e5 338 return; // empty frame
nixnax 142:54d1543e23e5 339 }
nixnax 145:098b6ed2f7f2 340 fcsReset();
nixnax 142:54d1543e23e5 341 char * dest = ppp.pkt.buf;
nixnax 142:54d1543e23e5 342 ppp.pkt.len=0;
nixnax 142:54d1543e23e5 343 int unstuff=0;
nixnax 142:54d1543e23e5 344 int idx = start;
nixnax 142:54d1543e23e5 345 while(1) {
nixnax 142:54d1543e23e5 346 checkPc();
nixnax 142:54d1543e23e5 347 if (unstuff==0) {
nixnax 142:54d1543e23e5 348 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 142:54d1543e23e5 349 else {
nixnax 142:54d1543e23e5 350 *dest = ppp.rx.buf[idx];
nixnax 142:54d1543e23e5 351 ppp.pkt.len++;
nixnax 142:54d1543e23e5 352 dest++;
nixnax 145:098b6ed2f7f2 353 fcsDo(ppp.rx.buf[idx]);
nixnax 142:54d1543e23e5 354 }
nixnax 142:54d1543e23e5 355 } else { // unstuff characters prefixed with 0x7d
nixnax 142:54d1543e23e5 356 *dest = ppp.rx.buf[idx]^0x20;
nixnax 142:54d1543e23e5 357 ppp.pkt.len++;
nixnax 142:54d1543e23e5 358 dest++;
nixnax 145:098b6ed2f7f2 359 fcsDo(ppp.rx.buf[idx]^0x20);
nixnax 142:54d1543e23e5 360 unstuff=0;
nixnax 142:54d1543e23e5 361 }
nixnax 142:54d1543e23e5 362 idx = (idx+1) & (RXBUFLEN-1);
nixnax 142:54d1543e23e5 363 if (idx == end) break;
nixnax 142:54d1543e23e5 364 }
nixnax 145:098b6ed2f7f2 365 ppp.pkt.crc = ppp.fcs & 0xffff;
nixnax 142:54d1543e23e5 366 if(0) dumpPPPFrame(); // set to 1 to dump ALL ppp frames
nixnax 142:54d1543e23e5 367 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 142:54d1543e23e5 368 determinePacketType();
nixnax 142:54d1543e23e5 369 } else {
nixnax 142:54d1543e23e5 370 #define REPORT_FCS_ERROR_YES
nixnax 142:54d1543e23e5 371 #ifdef REPORT_FCS_ERROR_YES
nixnax 142:54d1543e23e5 372 char pbuf[50]; // local print buffer
nixnax 142:54d1543e23e5 373 checkPc();
nixnax 142:54d1543e23e5 374 sprintf(pbuf, "\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // print a debug line
nixnax 142:54d1543e23e5 375 checkPc();
nixnax 142:54d1543e23e5 376 putsWhileCheckingInput( pbuf );
nixnax 142:54d1543e23e5 377 if(0) dumpPPPFrame(); // set to 1 to dump frames with errors in them
nixnax 142:54d1543e23e5 378 #endif
nixnax 142:54d1543e23e5 379 }
nixnax 142:54d1543e23e5 380 }
nixnax 142:54d1543e23e5 381
nixnax 142:54d1543e23e5 382 /// output a character to the PPP port while checking for incoming characters
nixnax 142:54d1543e23e5 383 void pcPutcWhileCheckingInput(int ch)
nixnax 142:54d1543e23e5 384 {
nixnax 142:54d1543e23e5 385 checkPc(); // check input
nixnax 142:54d1543e23e5 386 pc.putc(ch);
nixnax 142:54d1543e23e5 387 checkPc();
nixnax 142:54d1543e23e5 388 }
nixnax 142:54d1543e23e5 389
nixnax 142:54d1543e23e5 390 /// do PPP HDLC-like handling of special (flag) characters
nixnax 143:c5019f856a56 391 void hdlcPut(int ch)
nixnax 142:54d1543e23e5 392 {
nixnax 142:54d1543e23e5 393 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 142:54d1543e23e5 394 pcPutcWhileCheckingInput(0x7d);
nixnax 142:54d1543e23e5 395 pcPutcWhileCheckingInput(ch^0x20); // these characters need special handling
nixnax 142:54d1543e23e5 396 } else {
nixnax 142:54d1543e23e5 397 pcPutcWhileCheckingInput(ch);
nixnax 142:54d1543e23e5 398 }
nixnax 142:54d1543e23e5 399 }
nixnax 142:54d1543e23e5 400
nixnax 142:54d1543e23e5 401 /// send a PPP frame in HDLC format
nixnax 144:01d98cf7738e 402 void sendPppFrame()
nixnax 143:c5019f856a56 403 {
nixnax 145:098b6ed2f7f2 404 int crc = fcsBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 142:54d1543e23e5 405 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 142:54d1543e23e5 406 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 142:54d1543e23e5 407 pcPutcWhileCheckingInput(0x7e); // hdlc start-of-frame "flag"
nixnax 142:54d1543e23e5 408 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 142:54d1543e23e5 409 wait_us(86); // wait one character time
nixnax 142:54d1543e23e5 410 checkPc();
nixnax 142:54d1543e23e5 411 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 142:54d1543e23e5 412 }
nixnax 142:54d1543e23e5 413 pcPutcWhileCheckingInput(0x7e); // hdlc end-of-frame "flag"
nixnax 142:54d1543e23e5 414 }
nixnax 142:54d1543e23e5 415
nixnax 143:c5019f856a56 416 /// 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 417 int bufferToIP(char * buffer)
nixnax 143:c5019f856a56 418 {
nixnax 143:c5019f856a56 419 int result=0;
nixnax 143:c5019f856a56 420 for(int i=0; i<4; i++) result = (result<<8)|(*buffer++ & 0xff);
nixnax 143:c5019f856a56 421 return result;
nixnax 143:c5019f856a56 422 }
nixnax 143:c5019f856a56 423
nixnax 142:54d1543e23e5 424 /// handle IPCP configuration requests
nixnax 142:54d1543e23e5 425 void ipcpConfigRequestHandler()
nixnax 142:54d1543e23e5 426 {
nixnax 142:54d1543e23e5 427 debugPrintf("Their IPCP Config Req, Our Ack\n");
nixnax 143:c5019f856a56 428 if(ppp.pkt.buf[8]==3) {
nixnax 143:c5019f856a56 429 ppp.hostIP = bufferToIP(ppp.pkt.buf+10);
nixnax 143:c5019f856a56 430 debugPrintf("Host IP = %d.%d.%d.%d (%08x)\n", ppp.pkt.buf[10],ppp.pkt.buf[11],ppp.pkt.buf[12],ppp.pkt.buf[13],ppp.hostIP);
nixnax 143:c5019f856a56 431 }
nixnax 143:c5019f856a56 432
nixnax 142:54d1543e23e5 433 ppp.pkt.buf[4]=2; // change code to ack
nixnax 144:01d98cf7738e 434 sendPppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax 142:54d1543e23e5 435
nixnax 142:54d1543e23e5 436 debugPrintf("Our IPCP Ask (no options)\n");
nixnax 142:54d1543e23e5 437 ppp.pkt.buf[4]=1; // change code to request
nixnax 142:54d1543e23e5 438 ppp.pkt.buf[7]=4; // no options in this request
nixnax 142:54d1543e23e5 439 ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax 144:01d98cf7738e 440 sendPppFrame(); // send our request
nixnax 142:54d1543e23e5 441 }
nixnax 142:54d1543e23e5 442
nixnax 142:54d1543e23e5 443 /// handle IPCP acknowledge (do nothing)
nixnax 142:54d1543e23e5 444 void ipcpAckHandler()
nixnax 142:54d1543e23e5 445 {
nixnax 142:54d1543e23e5 446 debugPrintf("Their IPCP Grant\n");
nixnax 142:54d1543e23e5 447 }
nixnax 142:54d1543e23e5 448
nixnax 143:c5019f856a56 449 /// Handle IPCP NACK by sending our suggested IP address if there is an IP involved.
nixnax 143:c5019f856a56 450 /// 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 451 void ipcpNackHandler()
nixnax 142:54d1543e23e5 452 {
nixnax 146:a45f49a2b29c 453 debugPrintf("Their IPCP Nack\n");
nixnax 142:54d1543e23e5 454 if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax 142:54d1543e23e5 455 ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax 144:01d98cf7738e 456 sendPppFrame(); // let's request this IP address as ours
nixnax 143:c5019f856a56 457 debugPrintf("Our IPCP ACK (received an IP)\n");
nixnax 146:a45f49a2b29c 458 } else { // if it's not an IP nack we ignore it
nixnax 146:a45f49a2b29c 459 debugPrintf("IPCP Nack Ignored\n");
nixnax 146:a45f49a2b29c 460 }
nixnax 142:54d1543e23e5 461 }
nixnax 142:54d1543e23e5 462
nixnax 142:54d1543e23e5 463 /// handle all other IPCP requests (by ignoring them)
nixnax 142:54d1543e23e5 464 void ipcpDefaultHandler()
nixnax 142:54d1543e23e5 465 {
nixnax 142:54d1543e23e5 466 debugPrintf("Their IPCP Other\n");
nixnax 142:54d1543e23e5 467 }
nixnax 142:54d1543e23e5 468
nixnax 142:54d1543e23e5 469 /// process an incoming IPCP packet
nixnax 142:54d1543e23e5 470 void IPCPframe()
nixnax 142:54d1543e23e5 471 {
nixnax 142:54d1543e23e5 472 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 142:54d1543e23e5 473 switch (code) {
nixnax 142:54d1543e23e5 474 case 1:
nixnax 142:54d1543e23e5 475 ipcpConfigRequestHandler();
nixnax 142:54d1543e23e5 476 break;
nixnax 142:54d1543e23e5 477 case 2:
nixnax 142:54d1543e23e5 478 ipcpAckHandler();
nixnax 142:54d1543e23e5 479 break;
nixnax 142:54d1543e23e5 480 case 3:
nixnax 142:54d1543e23e5 481 ipcpNackHandler();
nixnax 142:54d1543e23e5 482 break;
nixnax 142:54d1543e23e5 483 default:
nixnax 142:54d1543e23e5 484 ipcpDefaultHandler();
nixnax 142:54d1543e23e5 485 }
nixnax 142:54d1543e23e5 486 }
nixnax 142:54d1543e23e5 487
nixnax 142:54d1543e23e5 488 /// perform a 16-bit checksum. if the byte count is odd, stuff in an extra zero byte.
nixnax 159:4d1bf96a59cd 489 unsigned int dataCheckSum(unsigned char * ptr, int len, int restart)
nixnax 142:54d1543e23e5 490 {
nixnax 159:4d1bf96a59cd 491 unsigned int i,hi,lo;
nixnax 142:54d1543e23e5 492 unsigned char placeHolder;
nixnax 142:54d1543e23e5 493 if (len&1) {
nixnax 142:54d1543e23e5 494 placeHolder = ptr[len];
nixnax 142:54d1543e23e5 495 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 496 }
nixnax 159:4d1bf96a59cd 497 if (restart) ppp.sum=0;
nixnax 142:54d1543e23e5 498 i=0;
nixnax 142:54d1543e23e5 499 while ( i<len ) {
nixnax 142:54d1543e23e5 500 checkPc();
nixnax 142:54d1543e23e5 501 hi = ptr[i++];
nixnax 142:54d1543e23e5 502 lo = ptr[i++];
nixnax 159:4d1bf96a59cd 503 ppp.sum = ppp.sum + ((hi<<8)|lo);
nixnax 142:54d1543e23e5 504 }
nixnax 142:54d1543e23e5 505 if (len&1) {
nixnax 142:54d1543e23e5 506 ptr[len] = placeHolder; // restore the extra byte we made zero
nixnax 142:54d1543e23e5 507 }
nixnax 159:4d1bf96a59cd 508 ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16);
nixnax 159:4d1bf96a59cd 509 ppp.sum = (ppp.sum & 0xffff) + (ppp.sum>>16); // sum one more time to catch any carry from the carry
nixnax 159:4d1bf96a59cd 510 return ~ppp.sum;
nixnax 142:54d1543e23e5 511 }
nixnax 142:54d1543e23e5 512
nixnax 142:54d1543e23e5 513 /// perform the checksum on an IP header
nixnax 146:a45f49a2b29c 514 void IpHeaderCheckSum()
nixnax 142:54d1543e23e5 515 {
nixnax 146:a45f49a2b29c 516 ppp.pkt.buf[4+10]=0; // zero the checsum in the IP header
nixnax 146:a45f49a2b29c 517 ppp.pkt.buf[4+11]=0; // zero the checksum in the IP header
nixnax 146:a45f49a2b29c 518 int len =(ppp.pkt.buf[4]&0xf)*4; // length of IP header in bytes
nixnax 146:a45f49a2b29c 519 char * ptr = ppp.pkt.buf+4; // start of IP packet
nixnax 142:54d1543e23e5 520 int sum=0;
nixnax 142:54d1543e23e5 521 for (int i=0; i<len/2; i++) {
nixnax 142:54d1543e23e5 522 int hi = *ptr;
nixnax 142:54d1543e23e5 523 ptr++;
nixnax 142:54d1543e23e5 524 int lo = *ptr;
nixnax 142:54d1543e23e5 525 ptr++;
nixnax 142:54d1543e23e5 526 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 142:54d1543e23e5 527 sum = sum + val;
nixnax 142:54d1543e23e5 528 checkPc();
nixnax 142:54d1543e23e5 529 }
nixnax 142:54d1543e23e5 530 sum = sum + (sum>>16);
nixnax 142:54d1543e23e5 531 sum = ~sum;
nixnax 146:a45f49a2b29c 532 ppp.pkt.buf[4+10]= (sum>>8);
nixnax 146:a45f49a2b29c 533 ppp.pkt.buf[4+11]= (sum );
nixnax 146:a45f49a2b29c 534 }
nixnax 146:a45f49a2b29c 535
nixnax 147:0f40005cbc5f 536 /// swap the IP source and destination addresses
nixnax 147:0f40005cbc5f 537 void swapIpAddresses()
nixnax 147:0f40005cbc5f 538 {
nixnax 147:0f40005cbc5f 539 char tempHold[4];
nixnax 147:0f40005cbc5f 540 memcpy(tempHold, ppp.pkt.buf+16,4); // tempHold <- source IP
nixnax 147:0f40005cbc5f 541 memcpy(ppp.pkt.buf+16, ppp.pkt.buf+20,4); // source <- dest
nixnax 147:0f40005cbc5f 542 memcpy(ppp.pkt.buf+20, tempHold,4); // dest <- tempHold
nixnax 147:0f40005cbc5f 543 }
nixnax 147:0f40005cbc5f 544
nixnax 149:969d98f6fb88 545 /// swap the IP source and destination ports
nixnax 149:969d98f6fb88 546 void swapIpPorts()
nixnax 149:969d98f6fb88 547 {
nixnax 149:969d98f6fb88 548 int headerSizeIP = 4*(ppp.pkt.buf[4]&0xf); // calculate size of IP header
nixnax 149:969d98f6fb88 549 char * ipSrcPort = 4 + ppp.pkt.buf + headerSizeIP + 0; // ip source port location
nixnax 149:969d98f6fb88 550 char * ipDstPort = 4 + ppp.pkt.buf + headerSizeIP + 2; // ip destin port location
nixnax 149:969d98f6fb88 551 char tempHold[2];
nixnax 149:969d98f6fb88 552 memcpy(tempHold, ipSrcPort,2); // tempHold <- source
nixnax 149:969d98f6fb88 553 memcpy(ipSrcPort,ipDstPort,2); // source <- dest
nixnax 149:969d98f6fb88 554 memcpy(ipDstPort,tempHold, 2); // dest <- tempHold
nixnax 149:969d98f6fb88 555 }
nixnax 149:969d98f6fb88 556
nixnax 146:a45f49a2b29c 557 /// Process an incoming UDP packet.
nixnax 146:a45f49a2b29c 558 /// If the packet starts with the string "echo " or "test" we echo back a special packet
nixnax 146:a45f49a2b29c 559 void UDPpacket()
nixnax 146:a45f49a2b29c 560 {
nixnax 146:a45f49a2b29c 561 char * ipHeader = ppp.pkt.buf+4; // udp packet start
nixnax 146:a45f49a2b29c 562 char * ipSizeBuf = ipHeader+2; // size of IP packet
nixnax 146:a45f49a2b29c 563 int headerSizeIP = 4*(ipHeader[0]&0xf); // size of IP header
nixnax 146:a45f49a2b29c 564 char * udpHeader = ipHeader + headerSizeIP; // udp info start
nixnax 146:a45f49a2b29c 565 char * udpLen = udpHeader+4; // udp data length
nixnax 146:a45f49a2b29c 566 char * udpCheckSum = udpHeader+6; // udp checksum
nixnax 146:a45f49a2b29c 567 char * udpData = udpHeader+8; // start of UDP data
nixnax 146:a45f49a2b29c 568 int udpLength = ((udpLen[0]<<8) | udpLen[1]); // size of udp packet
nixnax 146:a45f49a2b29c 569 int udpDataSize = udpLength - 8; // size of udp data
nixnax 147:0f40005cbc5f 570
nixnax 146:a45f49a2b29c 571 #ifdef SERIAL_PORT_MONITOR_YES
nixnax 147:0f40005cbc5f 572 char * srcIP = ipHeader+12; // IP source
nixnax 147:0f40005cbc5f 573 char * dstIP = ipHeader+16; // IP destination
nixnax 149:969d98f6fb88 574 char * udpSrcPort = udpHeader+0; // source port
nixnax 149:969d98f6fb88 575 char * udpDstPort = udpHeader+2; // destination port
nixnax 146:a45f49a2b29c 576 int udpSrc = (udpSrcPort[0]<<8)|udpSrcPort[1]; // integer of UDP source port
nixnax 146:a45f49a2b29c 577 int udpDst = (udpDstPort[0]<<8)|udpDstPort[1]; // integer of UDP dest port
nixnax 146:a45f49a2b29c 578 if(v0) debugPrintf("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],udpSrc);
nixnax 146:a45f49a2b29c 579 if(v0) debugPrintf("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],udpDst);
nixnax 146:a45f49a2b29c 580 if(v0) debugPrintf("Len %03d", udpLength);
nixnax 146:a45f49a2b29c 581 if (v1) {
nixnax 146:a45f49a2b29c 582 int printSize = udpLength-8;
nixnax 146:a45f49a2b29c 583 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 146:a45f49a2b29c 584 for (int i=0; i<printSize; i++) {
nixnax 146:a45f49a2b29c 585 char ch = udpData[i];
nixnax 146:a45f49a2b29c 586 if (ch>31 && ch<127) {
nixnax 146:a45f49a2b29c 587 debugPrintf("%c", ch);
nixnax 146:a45f49a2b29c 588 } else {
nixnax 146:a45f49a2b29c 589 debugPrintf("_");
nixnax 146:a45f49a2b29c 590 }
nixnax 146:a45f49a2b29c 591 }
nixnax 146:a45f49a2b29c 592 }
nixnax 146:a45f49a2b29c 593 if (v0) debugPrintf("\n");
nixnax 146:a45f49a2b29c 594 #endif
nixnax 146:a45f49a2b29c 595 int echoFound = !strncmp(udpData,"echo ",5); // true if UDP message starts with "echo "
nixnax 146:a45f49a2b29c 596 int testFound = !strncmp(udpData,"test" ,4); // true if UDP message starts with "test"
nixnax 146:a45f49a2b29c 597 if ( (echoFound) || (testFound)) { // if the UDP message starts with "echo " or "test" we answer back
nixnax 147:0f40005cbc5f 598 swapIpAddresses(); // swap IP source and destination
nixnax 149:969d98f6fb88 599 swapIpPorts(); // swap IP source and destination ports
nixnax 146:a45f49a2b29c 600 if (echoFound) {
nixnax 146:a45f49a2b29c 601 memcpy(udpData,"Got{",4); // in the UDP data modify "echo" to "Got:"
nixnax 146:a45f49a2b29c 602 char endString[] = "} UDP Server: PPP-Blinky\n"; // an appendix
nixnax 146:a45f49a2b29c 603 memcpy(udpData+udpLength-8,endString,sizeof(endString)-1); // add endstring size to the UDP message
nixnax 146:a45f49a2b29c 604 udpDataSize = udpDataSize + sizeof(endString)-1; // update udp data size with the size of the appendix
nixnax 146:a45f49a2b29c 605 }
nixnax 146:a45f49a2b29c 606 if (testFound) {
nixnax 146:a45f49a2b29c 607 char udpResponse[50];
nixnax 146:a45f49a2b29c 608 int n = 0;
nixnax 146:a45f49a2b29c 609 n = n+sprintf(udpResponse+n,"Response count %d\n",ppp.responseCounter++);
nixnax 146:a45f49a2b29c 610 memcpy(udpData,udpResponse,n); // copy response to the UDP data area
nixnax 146:a45f49a2b29c 611 udpDataSize = n; // new udp data size
nixnax 146:a45f49a2b29c 612 }
nixnax 146:a45f49a2b29c 613 udpLength = udpDataSize+8; // update udp packet length
nixnax 146:a45f49a2b29c 614 int ipSize = headerSizeIP + udpLength; // update ip packet length
nixnax 146:a45f49a2b29c 615 ppp.pkt.len = ipSize+2+4; // update ppp packet length
nixnax 146:a45f49a2b29c 616 udpLen[0] = udpLength>>8;
nixnax 146:a45f49a2b29c 617 udpLen[1] = udpLength; // update UDP length
nixnax 146:a45f49a2b29c 618 ipSizeBuf[0] = ipSize>>8;
nixnax 146:a45f49a2b29c 619 ipSizeBuf[1] = ipSize; // update IP length
nixnax 146:a45f49a2b29c 620 IpHeaderCheckSum(); // update IP header checksum
nixnax 146:a45f49a2b29c 621 memset(udpCheckSum,0,2); // we don't yet recompute the checksum (it's optional), so have to zero it
nixnax 146:a45f49a2b29c 622 sendPppFrame(); // send the UDP message back
nixnax 146:a45f49a2b29c 623 }
nixnax 142:54d1543e23e5 624 }
nixnax 142:54d1543e23e5 625
nixnax 142:54d1543e23e5 626 /// handle a PING ICMP (internet control message protocol) packet
nixnax 142:54d1543e23e5 627 void ICMPpacket() // internet control message protocol
nixnax 142:54d1543e23e5 628 {
nixnax 142:54d1543e23e5 629 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 142:54d1543e23e5 630 char * pktLen = ipPkt+2;
nixnax 142:54d1543e23e5 631 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 142:54d1543e23e5 632 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 142:54d1543e23e5 633 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 142:54d1543e23e5 634 char * icmpSum = icmpType+2; // icmp checksum
nixnax 142:54d1543e23e5 635 #define ICMP_TYPE_PING_REQUEST 8
nixnax 142:54d1543e23e5 636 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 142:54d1543e23e5 637 char * ipTTL = ipPkt+8; // time to live
nixnax 147:0f40005cbc5f 638 ipTTL[0]--; // decrement time to live (so we have to update header checksum)
nixnax 147:0f40005cbc5f 639 #ifdef SERIAL_PORT_MONITOR_YES
nixnax 142:54d1543e23e5 640 char * srcAdr = ipPkt+12;
nixnax 142:54d1543e23e5 641 char * dstAdr = ipPkt+16;
nixnax 142:54d1543e23e5 642 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 142:54d1543e23e5 643 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 142:54d1543e23e5 644 if(1) {
nixnax 142:54d1543e23e5 645 char pbuf[50];
nixnax 142:54d1543e23e5 646 checkPc();
nixnax 142:54d1543e23e5 647 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 648 putsWhileCheckingInput( pbuf );
nixnax 142:54d1543e23e5 649 checkPc();
nixnax 142:54d1543e23e5 650 sprintf(pbuf, "Ident %04x Sequence %04d \n",icmpIdent,icmpSequence);
nixnax 142:54d1543e23e5 651 checkPc();
nixnax 142:54d1543e23e5 652 putsWhileCheckingInput( pbuf );
nixnax 142:54d1543e23e5 653 }
nixnax 142:54d1543e23e5 654 #endif
nixnax 147:0f40005cbc5f 655 swapIpAddresses(); // swap the IP source and destination addresses
nixnax 147:0f40005cbc5f 656 IpHeaderCheckSum(); // new ip header checksum (required because we changed TTL)
nixnax 142:54d1543e23e5 657 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 142:54d1543e23e5 658 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 142:54d1543e23e5 659 icmpSum[0]=0;
nixnax 142:54d1543e23e5 660 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 142:54d1543e23e5 661 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 159:4d1bf96a59cd 662 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength, 1); // this checksum on icmp data portion
nixnax 142:54d1543e23e5 663 icmpSum[0]=(sum>>8)&0xff;
nixnax 142:54d1543e23e5 664 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 142:54d1543e23e5 665
nixnax 142:54d1543e23e5 666 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 142:54d1543e23e5 667 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 142:54d1543e23e5 668 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 142:54d1543e23e5 669 if (0) {
nixnax 142:54d1543e23e5 670 for (int i=0; i<printSize; i++) {
nixnax 142:54d1543e23e5 671 char ch = icmpData[i];
nixnax 142:54d1543e23e5 672 if (ch>31 && ch<127) {
nixnax 142:54d1543e23e5 673 putcWhileCheckingInput(ch);
nixnax 142:54d1543e23e5 674 } else {
nixnax 142:54d1543e23e5 675 putcWhileCheckingInput('_');
nixnax 142:54d1543e23e5 676 }
nixnax 142:54d1543e23e5 677 }
nixnax 142:54d1543e23e5 678 putcWhileCheckingInput('\n');
nixnax 142:54d1543e23e5 679 }
nixnax 144:01d98cf7738e 680 sendPppFrame(); // reply to the ping
nixnax 142:54d1543e23e5 681 } else {
nixnax 142:54d1543e23e5 682 if (v0) {
nixnax 142:54d1543e23e5 683 debugPrintf("ICMP type=%d \n", icmpType[0]);
nixnax 142:54d1543e23e5 684 }
nixnax 142:54d1543e23e5 685 }
nixnax 142:54d1543e23e5 686 }
nixnax 142:54d1543e23e5 687
nixnax 142:54d1543e23e5 688 /// handle an IGMP (internet group managment protocol) packet (by ignoring it)
nixnax 142:54d1543e23e5 689 void IGMPpacket()
nixnax 142:54d1543e23e5 690 {
nixnax 142:54d1543e23e5 691 if (v0) debugPrintf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 142:54d1543e23e5 692 }
nixnax 142:54d1543e23e5 693
nixnax 142:54d1543e23e5 694 /// dump the header of an IP pakcet on the (optional) debug serial port
nixnax 142:54d1543e23e5 695 void dumpHeaderIP (int outGoing)
nixnax 142:54d1543e23e5 696 {
nixnax 142:54d1543e23e5 697 #if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax 142:54d1543e23e5 698 checkPc(); // we are expecting the first character of the next packet
nixnax 155:9c6a1d249e26 699 int IPv4Id = __REV16(ppp.ip->identR);
nixnax 152:025c73b6c0a9 700 char pbuf[80]; // local print buffer
nixnax 142:54d1543e23e5 701 int n=0;
nixnax 142:54d1543e23e5 702 n=n+sprintf(pbuf+n, outGoing ? "\x1b[34m" : "\x1b[30m" ); // VT100 color code, print black for incoming, blue for outgoing headers
nixnax 142:54d1543e23e5 703 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 704 #define DUMP_FULL_IP_ADDRESS_YES
nixnax 142:54d1543e23e5 705 #ifdef DUMP_FULL_IP_ADDRESS_YES
nixnax 154:18b2bd92f557 706 char * srcAdr = (char *)&ppp.ip->srcAdrR; // 4 bytes
nixnax 154:18b2bd92f557 707 char * dstAdr = (char *)&ppp.ip->dstAdrR; // 4 bytes = total of 20 bytes
nixnax 152:025c73b6c0a9 708 //n=n+sprintf(pbuf+n, " %x %x ", ppp.pkt.ip.x, ppp.pkt.ip.y);
nixnax 142:54d1543e23e5 709 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 710 #endif
nixnax 142:54d1543e23e5 711 putsWhileCheckingInput( pbuf );
nixnax 142:54d1543e23e5 712 #ifndef TCP_HEADER_DUMP_YES
nixnax 142:54d1543e23e5 713 putsWhileCheckingInput('\x1b[30m\n'); // there is no TCP header dump, so terminate the line with \n and VT100 code for black
nixnax 142:54d1543e23e5 714 #endif
nixnax 142:54d1543e23e5 715 #endif
nixnax 142:54d1543e23e5 716 }
nixnax 142:54d1543e23e5 717
nixnax 142:54d1543e23e5 718 /// dump a TCP header on the optional debug serial port
nixnax 142:54d1543e23e5 719 void dumpHeaderTCP(int outGoing)
nixnax 142:54d1543e23e5 720 {
nixnax 142:54d1543e23e5 721 #if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax 155:9c6a1d249e26 722 char flagString[9]; // text string presenting the 8 most important TCP flags
nixnax 142:54d1543e23e5 723 #define PRINT_ALL_TCP_FLAGS_YES
nixnax 142:54d1543e23e5 724 #ifdef PRINT_ALL_TCP_FLAGS_YES
nixnax 155:9c6a1d249e26 725 memset(flagString,'.', 8); // fill string with "........"
nixnax 156:163c23249731 726 if (ppp.tcp->flag.fin) flagString[7]='F';
nixnax 156:163c23249731 727 if (ppp.tcp->flag.syn) flagString[6]='S';
nixnax 156:163c23249731 728 if (ppp.tcp->flag.rst) flagString[5]='R';
nixnax 156:163c23249731 729 if (ppp.tcp->flag.psh) flagString[4]='P';
nixnax 156:163c23249731 730 if (ppp.tcp->flag.ack) flagString[3]='A';
nixnax 156:163c23249731 731 if (ppp.tcp->flag.urg) flagString[2]='U';
nixnax 156:163c23249731 732 if (ppp.tcp->flag.ece) flagString[1]='E';
nixnax 156:163c23249731 733 if (ppp.tcp->flag.cwr) flagString[0]='C';
nixnax 155:9c6a1d249e26 734 flagString[8]=0; // null terminate string
nixnax 142:54d1543e23e5 735 #else
nixnax 156:163c23249731 736 if (ppp.tcp->flag.ack) flagString[0]='A'; // choose only the most important flag to print
nixnax 156:163c23249731 737 if (ppp.tcp->flag.syn) flagString[0]='S';
nixnax 156:163c23249731 738 if (ppp.tcp->flag.fin) flagString[0]='F';
nixnax 156:163c23249731 739 if (ppp.tcp->flag.psh) flagString[0]='P';
nixnax 156:163c23249731 740 if (ppp.tcp->flag.rst) flagString[0]='R';
nixnax 155:9c6a1d249e26 741 flagString[1]=0; // null terminate string
nixnax 142:54d1543e23e5 742 #endif
nixnax 155:9c6a1d249e26 743 putsWhileCheckingInput( flagString );
nixnax 142:54d1543e23e5 744 #define EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax 142:54d1543e23e5 745 #ifdef EVERY_PACKET_ON_A_NEW_LINE_YES
nixnax 142:54d1543e23e5 746 putsWhileCheckingInput("\x1b[30m\n"); // write a black color and newline after every packet
nixnax 142:54d1543e23e5 747 #endif
nixnax 156:163c23249731 748 if( outGoing && ppp.tcp->flag.fin ) { // ACK/FIN - if this is an outgoing FIN it's the end of a tcp conversation
nixnax 156:163c23249731 749 putcWhileCheckingInput('\n'); // insert an extra new line to mark the end of an HTTP conversation
nixnax 142:54d1543e23e5 750 }
nixnax 142:54d1543e23e5 751 #endif
nixnax 142:54d1543e23e5 752 }
nixnax 142:54d1543e23e5 753
nixnax 143:c5019f856a56 754 /// Encode a buffer in base-64
nixnax 142:54d1543e23e5 755 void enc64(char * in, char * out, int len)
nixnax 142:54d1543e23e5 756 {
nixnax 142:54d1543e23e5 757 const static char lut [] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
nixnax 142:54d1543e23e5 758 int i,j,a,b,c;
nixnax 142:54d1543e23e5 759 i=0;
nixnax 142:54d1543e23e5 760 j=0;
nixnax 142:54d1543e23e5 761 while(1) {
nixnax 142:54d1543e23e5 762 if (i<len) {
nixnax 142:54d1543e23e5 763 a = in[i++];
nixnax 142:54d1543e23e5 764 out[j++] = lut[ ( (a >> 2) & 0x3f) ];
nixnax 142:54d1543e23e5 765 } else break;
nixnax 142:54d1543e23e5 766 if (i<len) {
nixnax 142:54d1543e23e5 767 b = in[i++];
nixnax 142:54d1543e23e5 768 out[j++] = lut[ ( (a << 4) & 0x30) | ( (b >> 4) & 0x0f) ];
nixnax 142:54d1543e23e5 769 out[j++] = lut[ ( (b << 2) & 0x3c) ];
nixnax 142:54d1543e23e5 770 } else out[j++] = '=';
nixnax 142:54d1543e23e5 771 if (i<len) {
nixnax 142:54d1543e23e5 772 c = in[i++];
nixnax 142:54d1543e23e5 773 j--;
nixnax 142:54d1543e23e5 774 out[j++] = lut[ ( (b << 2) & 0x3c) | ( (c >> 6) & 0x03) ];
nixnax 142:54d1543e23e5 775 out[j++] = lut[ ( (c >> 0) & 0x3f) ];
nixnax 142:54d1543e23e5 776 } else out[j++] = '=';
nixnax 142:54d1543e23e5 777 }
nixnax 142:54d1543e23e5 778 out[j]=0;
nixnax 142:54d1543e23e5 779 }
nixnax 142:54d1543e23e5 780
nixnax 142:54d1543e23e5 781 /// handle a request for an http websocket
nixnax 142:54d1543e23e5 782 /// 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 783 int webSocketHandler(char * dataStart)
nixnax 142:54d1543e23e5 784 {
nixnax 142:54d1543e23e5 785 int n=0; // byte counter
nixnax 142:54d1543e23e5 786 char * key = strstr(dataStart, "Sec-WebSocket-Key: "); // search for the key in the payload
nixnax 142:54d1543e23e5 787 if (key != NULL) {
nixnax 142:54d1543e23e5 788 if (v0) putsWhileCheckingInput("WebSocket Request\n");
nixnax 142:54d1543e23e5 789 char challenge [70];
nixnax 142:54d1543e23e5 790 strncpy(challenge,key+19,70); // a local buffer
nixnax 142:54d1543e23e5 791 *strchr(challenge,'\r')=0; // insert null so we can use sprintf
nixnax 142:54d1543e23e5 792 strncat(challenge,"258EAFA5-E914-47DA-95CA-C5AB0DC85B11",70); // append websocket gui code
nixnax 142:54d1543e23e5 793 char shaOutput [20]; // sha1 output
nixnax 142:54d1543e23e5 794 sha1( shaOutput, challenge, strlen(challenge));
nixnax 142:54d1543e23e5 795 char encOut[50];
nixnax 142:54d1543e23e5 796 enc64( shaOutput, encOut, 20);
nixnax 142:54d1543e23e5 797 char * versionstring = strstr(dataStart, "Sec-WebSocket-Version:");
nixnax 142:54d1543e23e5 798 char * version = challenge;
nixnax 142:54d1543e23e5 799 strncpy(version, versionstring,70); // copy version string
nixnax 142:54d1543e23e5 800 *strchr(version,'\r')=0; // null terminate so we can sprintf it
nixnax 142:54d1543e23e5 801 memset(dataStart,0,500); // blank out old data befor send the websocket response header
nixnax 142:54d1543e23e5 802 n=n+sprintf(dataStart+n, "HTTP/1.1 101 Switching Protocols\r\n");
nixnax 142:54d1543e23e5 803 n=n+sprintf(dataStart+n, "Upgrade: websocket\r\n");
nixnax 142:54d1543e23e5 804 n=n+sprintf(dataStart+n, "Connection: Upgrade\r\n");
nixnax 142:54d1543e23e5 805 n=n+sprintf(dataStart+n, "Sec-WebSocket-Accept: %s\r\n",encOut);
nixnax 142:54d1543e23e5 806 n=n+sprintf(dataStart+n, "%s\r\n",version);
nixnax 142:54d1543e23e5 807 n=n+sprintf(dataStart+n, "mbed-Code: PPP-Blinky\r\n");
nixnax 142:54d1543e23e5 808 n=n+sprintf(dataStart+n, "\r\n"); // websocket response header ending
nixnax 142:54d1543e23e5 809 }
nixnax 142:54d1543e23e5 810 return n; // this response should satisfy a web browser's websocket protocol request
nixnax 142:54d1543e23e5 811 }
nixnax 142:54d1543e23e5 812
nixnax 142:54d1543e23e5 813 #define TCP_FLAG_ACK (1<<4)
nixnax 142:54d1543e23e5 814 #define TCP_FLAG_SYN (1<<1)
nixnax 142:54d1543e23e5 815 #define TCP_FLAG_PSH (1<<3)
nixnax 142:54d1543e23e5 816 #define TCP_FLAG_RST (1<<2)
nixnax 142:54d1543e23e5 817 #define TCP_FLAG_FIN (1<<0)
nixnax 142:54d1543e23e5 818
nixnax 142:54d1543e23e5 819 /// respond to an HTTP request
nixnax 142:54d1543e23e5 820 int httpResponse(char * dataStart)
nixnax 142:54d1543e23e5 821 {
nixnax 142:54d1543e23e5 822 int n=0; // number of bytes we have printed so far
nixnax 142:54d1543e23e5 823 n = webSocketHandler( dataStart ); // test for and handle WebSocket upgrade requests
nixnax 142:54d1543e23e5 824 if (n>0) return n; // if it's a WebSocket we already have the response, so return
nixnax 142:54d1543e23e5 825
nixnax 142:54d1543e23e5 826 int nHeader; // byte size of HTTP header
nixnax 142:54d1543e23e5 827 int contentLengthStart; // index where HTML starts
nixnax 142:54d1543e23e5 828 int httpGet5,httpGet6,httpGetx, httpGetRoot; // temporary storage of strncmp results
nixnax 142:54d1543e23e5 829
nixnax 146:a45f49a2b29c 830 ppp.responseCounter++; // increment the number of frames we have made
nixnax 142:54d1543e23e5 831
nixnax 142:54d1543e23e5 832 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found a GET to the root directory
nixnax 142:54d1543e23e5 833 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 834 httpGet5 = dataStart[5]; // the first character in the path name, we use it for special functions later on
nixnax 142:54d1543e23e5 835 httpGet6 = dataStart[6]; // the second character in the path name, we use it for special functions later on
nixnax 142:54d1543e23e5 836 // for example, you could try this using netcat (nc): echo "GET /x" | nc 172.10.10.2
nixnax 142:54d1543e23e5 837 if( (httpGetRoot==0) || (httpGetx==0) ) {
nixnax 142:54d1543e23e5 838 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky-v1\r\n"); // 200 OK header
nixnax 142:54d1543e23e5 839 } else {
nixnax 142:54d1543e23e5 840 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 142:54d1543e23e5 841 }
nixnax 142:54d1543e23e5 842 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 142:54d1543e23e5 843 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 142:54d1543e23e5 844 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 142:54d1543e23e5 845 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 142:54d1543e23e5 846 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 847 nHeader=n; // size of HTTP header
nixnax 142:54d1543e23e5 848 if( httpGetRoot == 0 ) {
nixnax 142:54d1543e23e5 849 // this is where we insert our web page into the buffer
nixnax 142:54d1543e23e5 850 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 142:54d1543e23e5 851 n = n + sizeof(rootWebPage)-1; // one less than sizeof because we don't count the null byte at the end
nixnax 142:54d1543e23e5 852 } else if ( (httpGet5 == 'w') && (httpGet6 == 's') ) { // "ws" is a special page for websocket demo
nixnax 142:54d1543e23e5 853 memcpy(n+dataStart,webSocketPage,sizeof(webSocketPage));
nixnax 142:54d1543e23e5 854 n = n + sizeof(webSocketPage)-1; // one less than size
nixnax 142:54d1543e23e5 855 } else {
nixnax 142:54d1543e23e5 856 if (httpGetx == 0) { // the page request started with "GET /x" - here we treat anything starting with /x special:
nixnax 142:54d1543e23e5 857
nixnax 142:54d1543e23e5 858 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 142:54d1543e23e5 859 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 142:54d1543e23e5 860 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 142:54d1543e23e5 861 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (W3C.org required elements)
nixnax 146:a45f49a2b29c 862 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.responseCounter); // body = the http frame count
nixnax 142:54d1543e23e5 863 #else
nixnax 142:54d1543e23e5 864 if( httpGet6 == 'b' ) { // if the fetched page is "xb" send a meta command to let the browser continuously reload
nixnax 142:54d1543e23e5 865 n=n+sprintf(n+dataStart, "<meta http-equiv=\"refresh\" content=\"0\">"); // reload loop - handy for benchmarking
nixnax 142:54d1543e23e5 866 }
nixnax 142:54d1543e23e5 867 // /x is a very short page, in fact, it is only a decimal number showing the http Page count
nixnax 146:a45f49a2b29c 868 n=n+sprintf(n+dataStart,"%d ",ppp.responseCounter); // not really valid html but most browsers and curl are ok with it
nixnax 142:54d1543e23e5 869 #endif
nixnax 142:54d1543e23e5 870 } else {
nixnax 142:54d1543e23e5 871 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 142:54d1543e23e5 872 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed PPP-Blinky</title>"); // html title (required element)
nixnax 142:54d1543e23e5 873 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 142:54d1543e23e5 874 }
nixnax 142:54d1543e23e5 875 }
nixnax 142:54d1543e23e5 876 #define CONTENTLENGTHSIZE 5
nixnax 142:54d1543e23e5 877 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 142:54d1543e23e5 878 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 142:54d1543e23e5 879 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 142:54d1543e23e5 880 return n; // total byte size of our response
nixnax 142:54d1543e23e5 881 }
nixnax 142:54d1543e23e5 882
nixnax 142:54d1543e23e5 883 /// handle TCP data that is not an HTTP get
nixnax 142:54d1543e23e5 884 /// this is the response if we have TCP data but it's not an HTTP GET
nixnax 142:54d1543e23e5 885 /// this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax 142:54d1543e23e5 886 /// this could also be a websocket receive event - especially if the first byte is 0x81 (websocket data push)
nixnax 142:54d1543e23e5 887 int tcpResponse(char * dataStart, int len, int * outFlags)
nixnax 142:54d1543e23e5 888 {
nixnax 142:54d1543e23e5 889 int n=0; // number of bytes we have printed so far
nixnax 142:54d1543e23e5 890 if (dataStart[0] == 0x81) { // check if this is a websocket push message
nixnax 142:54d1543e23e5 891 // this is most likely a websocket push message. you get this when you enter this in your browser console: x.send("my message");
nixnax 142:54d1543e23e5 892 if (0) putsWhileCheckingInput( "Got data from websocket send()\n" );
nixnax 142:54d1543e23e5 893
nixnax 142:54d1543e23e5 894 // for now we simply echo the websocket data back to the client - the client should therefore see an onmessage event
nixnax 142:54d1543e23e5 895 // to display the echoed data in your browser, enter the following into the browser console: x.onmessage = function(msg){ console.log( msg.data ); }
nixnax 142:54d1543e23e5 896 if (1) {
nixnax 142:54d1543e23e5 897 char mask [4];
nixnax 142:54d1543e23e5 898 memcpy ( mask, dataStart+2, 4); // websocket messages are "masked", so first we obtain the 4-byte mask
nixnax 142:54d1543e23e5 899 int websocketMessageSize = len - 6; // 1 byte prefix (0x81), 1 byte, 4 bytes mask = 6 bytes
nixnax 142:54d1543e23e5 900 if((dataStart[1]&0x80)==0x80) // test if the mask bit is set, which means all data is xor'ed with the mask
nixnax 142:54d1543e23e5 901 for (int i=0; i<websocketMessageSize; i++) dataStart[i+6]^= mask[i%4]; // unmask each byte with one of the mask bytes
nixnax 142:54d1543e23e5 902 dataStart[1] = len-2; // add four extra bytes to the message length because we don't use mask bytes for the send
nixnax 142:54d1543e23e5 903 memcpy(dataStart+2, "Got:",4); // insert our own text into the four mask bytes
nixnax 142:54d1543e23e5 904 n = len; // our response size remains exactly the same length as what we received
nixnax 142:54d1543e23e5 905 }
nixnax 142:54d1543e23e5 906 } else if ( (dataStart[0]==0x88) && (dataStart[1]==0x80) && (len == 6) ) { // test for a websocket close request
nixnax 142:54d1543e23e5 907 n=2; // our close command is only two bytes long because we don't use the four mask bytes
nixnax 142:54d1543e23e5 908 dataStart[1]=0; // we don't have mask bytes on
nixnax 142:54d1543e23e5 909 } else if (v1) putsWhileCheckingInput("TCP data received\n");
nixnax 142:54d1543e23e5 910 return n; // total byte size of our response
nixnax 142:54d1543e23e5 911 }
nixnax 142:54d1543e23e5 912
nixnax 142:54d1543e23e5 913 /// handle an incoming TCP packet
nixnax 142:54d1543e23e5 914 /// 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 915 void tcpHandler()
nixnax 142:54d1543e23e5 916 {
nixnax 142:54d1543e23e5 917 // IP header
nixnax 142:54d1543e23e5 918 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 142:54d1543e23e5 919 char * protocol = ipPkt+9; // 1 byte
nixnax 159:4d1bf96a59cd 920 char protocolIP = protocol[0];
nixnax 154:18b2bd92f557 921 int packetLengthIp = __REV16(ppp.ip->lengthR ); // size of ip packet
nixnax 154:18b2bd92f557 922 int headerSizeIp = 4 * ppp.ip->headerLength; // size of ip header
nixnax 142:54d1543e23e5 923
nixnax 142:54d1543e23e5 924 // TCP header
nixnax 155:9c6a1d249e26 925
nixnax 155:9c6a1d249e26 926 ppp.tcpStart = ppp.ipStart + headerSizeIp; // calculate where the TCP header starts
nixnax 154:18b2bd92f557 927 int tcpSize = packetLengthIp - headerSizeIp; // tcp size = size of ip payload
nixnax 154:18b2bd92f557 928 char * tcp = ppp.ipStart+headerSizeIp; // start of tcp packet
nixnax 142:54d1543e23e5 929
nixnax 154:18b2bd92f557 930 int headerSizeTcp = 4 * (ppp.tcp->offset); // tcp "offset" for start of data is also the header size
nixnax 152:025c73b6c0a9 931
nixnax 154:18b2bd92f557 932 char * tcpDataIn = tcp + headerSizeTcp; // start of data block after TCP header
nixnax 154:18b2bd92f557 933 int tcpDataSize = tcpSize - headerSizeTcp; // size of data block after TCP header
nixnax 154:18b2bd92f557 934
nixnax 154:18b2bd92f557 935 unsigned int seq_in = __REV(ppp.tcp->seqTcpR);
nixnax 154:18b2bd92f557 936 unsigned int ack_in = __REV(ppp.tcp->ackTcpR);
nixnax 142:54d1543e23e5 937 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 142:54d1543e23e5 938 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 142:54d1543e23e5 939
nixnax 142:54d1543e23e5 940 // first we shorten the TCP response header to only 20 bytes. This means we ignore all TCP option requests
nixnax 142:54d1543e23e5 941 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 154:18b2bd92f557 942 headerSizeTcp = 20; // shorten outgoing TCP header size 20 bytes
nixnax 154:18b2bd92f557 943 ppp.ip->headerLength = 5; // ip header is 20 bytes long
nixnax 154:18b2bd92f557 944 ppp.tcp->offset = (headerSizeTcp/4);
nixnax 154:18b2bd92f557 945 ppp.ip->lengthR = __REV(40);
nixnax 154:18b2bd92f557 946 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 154:18b2bd92f557 947
nixnax 154:18b2bd92f557 948 ppp.ip->lengthR = __REV16(40);
nixnax 142:54d1543e23e5 949
nixnax 142:54d1543e23e5 950 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 142:54d1543e23e5 951 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 155:9c6a1d249e26 952 //int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 159:4d1bf96a59cd 953
nixnax 159:4d1bf96a59cd 954 ppp.tcp->windowR = __REV16( 700 ); // set tcp window size to 700 bytes
nixnax 142:54d1543e23e5 955
nixnax 142:54d1543e23e5 956 // A sparse TCP flag interpreter that implements stateless TCP connections
nixnax 142:54d1543e23e5 957
nixnax 156:163c23249731 958 switch ( ppp.tcp->flag.All ) {
nixnax 158:841592aed956 959 case TCP_FLAG_ACK: // handle ack messages by ignoring them
nixnax 142:54d1543e23e5 960 return;
nixnax 142:54d1543e23e5 961 case TCP_FLAG_SYN:
nixnax 142:54d1543e23e5 962 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 142:54d1543e23e5 963 seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a starting point, increase the highest digit
nixnax 142:54d1543e23e5 964 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 142:54d1543e23e5 965 break;
nixnax 142:54d1543e23e5 966 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 142:54d1543e23e5 967 if ( (strncmp(tcpDataIn, "GET /", 5) == 0) ) { // check for an http GET command
nixnax 142:54d1543e23e5 968 flagsOut = TCP_FLAG_ACK | TCP_FLAG_PSH; // set outgoing FIN flag to ask them to close from their side
nixnax 142:54d1543e23e5 969 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 142:54d1543e23e5 970 } else {
nixnax 158:841592aed956 971 dataLen = tcpResponse(tcpDataOut,tcpDataSize, &flagsOut); // not an http GET, handle as a tcp connection
nixnax 142:54d1543e23e5 972 }
nixnax 142:54d1543e23e5 973 break;
nixnax 142:54d1543e23e5 974 case TCP_FLAG_FIN:
nixnax 142:54d1543e23e5 975 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 142:54d1543e23e5 976 case TCP_FLAG_FIN | TCP_FLAG_PSH | TCP_FLAG_ACK:
nixnax 142:54d1543e23e5 977 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax 142:54d1543e23e5 978 ack_out++; // for FIN flag we have to increase the sequence by 1
nixnax 142:54d1543e23e5 979 break;
nixnax 142:54d1543e23e5 980 default:
nixnax 142:54d1543e23e5 981 return; // ignore remaining packets
nixnax 142:54d1543e23e5 982 } // switch
nixnax 142:54d1543e23e5 983
nixnax 142:54d1543e23e5 984 // The TCP flag handling is now done
nixnax 142:54d1543e23e5 985 // first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax 147:0f40005cbc5f 986 swapIpAddresses(); // swap IP source and destination addresses
nixnax 149:969d98f6fb88 987 swapIpPorts(); // swap IP source and destination ports
nixnax 142:54d1543e23e5 988
nixnax 158:841592aed956 989 ppp.tcp->ackTcpR = __REV( ack_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax 158:841592aed956 990 ppp.tcp->seqTcpR = __REV( seq_out ); // byte reversed - tcp/ip messages are big-endian (high byte first)
nixnax 154:18b2bd92f557 991
nixnax 156:163c23249731 992 ppp.tcp->flag.All = flagsOut; // update the TCP flags
nixnax 142:54d1543e23e5 993
nixnax 159:4d1bf96a59cd 994 // recalculate all the header sizes
nixnax 154:18b2bd92f557 995 tcpSize = headerSizeTcp + dataLen; // tcp packet size
nixnax 154:18b2bd92f557 996 int newPacketSize = headerSizeIp + tcpSize; // calculate size of the outgoing packet
nixnax 159:4d1bf96a59cd 997 ppp.ip->lengthR = __REV16 ( newPacketSize );
nixnax 142:54d1543e23e5 998 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 999
nixnax 142:54d1543e23e5 1000 // the header is all set up, now do the IP and TCP checksums
nixnax 146:a45f49a2b29c 1001 IpHeaderCheckSum(); // calculate new IP header checksum
nixnax 142:54d1543e23e5 1002
nixnax 159:4d1bf96a59cd 1003 // create the TCP "pseudo-header" (containing some IP header values) in order to correctly calculate the TCP checksum
nixnax 142:54d1543e23e5 1004 // this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax 159:4d1bf96a59cd 1005 pseudoIpHeaderType pseudoHeader; // create pseudo header
nixnax 159:4d1bf96a59cd 1006 pseudoHeader.srcAdrR = ppp.ip->srcAdrR; // copy in ip source address
nixnax 159:4d1bf96a59cd 1007 pseudoHeader.dstAdrR = ppp.ip->dstAdrR; // copy in ip dest address
nixnax 159:4d1bf96a59cd 1008 pseudoHeader.zero = 0; // padding
nixnax 159:4d1bf96a59cd 1009 pseudoHeader.protocol = protocolIP; // protocol number
nixnax 159:4d1bf96a59cd 1010 pseudoHeader.lengthR = __REV16( tcpSize ); // size of tcp packet
nixnax 159:4d1bf96a59cd 1011 dataCheckSum(pseudoHeader.start, 12, 1); // start with the TCP checksum of the pseudoheader
nixnax 159:4d1bf96a59cd 1012 ppp.tcp->checksumR = 0; // before TCP checksum calculations the checksum bytes must be set cleared
nixnax 159:4d1bf96a59cd 1013 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)ppp.tcpStart,tcpSize, 0); // continue the TCP checksum on the whole TCP packet
nixnax 159:4d1bf96a59cd 1014 ppp.tcp->checksumR = __REV16( pseudoHeaderSum); // tcp checksum done, store it in the TCP header
nixnax 159:4d1bf96a59cd 1015
nixnax 142:54d1543e23e5 1016 dumpHeaderIP(1); // dump outgoing IP header
nixnax 142:54d1543e23e5 1017 dumpHeaderTCP(1); // dump outgoing TCP header
nixnax 142:54d1543e23e5 1018 for (int i=0; i<45*1000/10; i++) { // 45 ms delay before sending frame - a typical internet delay time
nixnax 142:54d1543e23e5 1019 checkPc(); // catch any incoming characters
nixnax 142:54d1543e23e5 1020 wait_us(10); // wait less than 1 character duration at 115200
nixnax 142:54d1543e23e5 1021 }
nixnax 144:01d98cf7738e 1022 sendPppFrame(); // All preparation complete - send the TCP response
nixnax 142:54d1543e23e5 1023 if(0) dumpPPPFrame(); // set to 1 to dump transmitted ppp frame
nixnax 142:54d1543e23e5 1024 memset(ppp.pkt.buf+44,0,500); // flush out traces of previous data that we may scan for
nixnax 142:54d1543e23e5 1025 }
nixnax 142:54d1543e23e5 1026
nixnax 142:54d1543e23e5 1027 /// dump the TCP data to the debug serial port
nixnax 142:54d1543e23e5 1028 void dumpDataTCP()
nixnax 142:54d1543e23e5 1029 {
nixnax 142:54d1543e23e5 1030 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 142:54d1543e23e5 1031 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 154:18b2bd92f557 1032 int headerSizeTcp = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 154:18b2bd92f557 1033 int dataLen = ipPktLen - ipHeaderLen - headerSizeTcp; // data is what's left after the two headers
nixnax 142:54d1543e23e5 1034 if (v1) {
nixnax 142:54d1543e23e5 1035 char pbuf[50]; // local print buffer
nixnax 142:54d1543e23e5 1036 checkPc();
nixnax 154:18b2bd92f557 1037 sprintf(pbuf, "TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTcp, dataLen); // 1 for more verbose
nixnax 142:54d1543e23e5 1038 checkPc();
nixnax 142:54d1543e23e5 1039 putsWhileCheckingInput( pbuf );
nixnax 142:54d1543e23e5 1040 }
nixnax 142:54d1543e23e5 1041 if (dataLen > 0) {
nixnax 154:18b2bd92f557 1042 ppp.pkt.buf[4+ipHeaderLen+headerSizeTcp+dataLen]=0; // insert a null after the data so debug printf stops printing after the data
nixnax 154:18b2bd92f557 1043 putsWhileCheckingInput( ppp.pkt.buf+4+ipHeaderLen+headerSizeTcp ); // print the tcp payload data
nixnax 142:54d1543e23e5 1044 putsWhileCheckingInput("\n");
nixnax 142:54d1543e23e5 1045 }
nixnax 142:54d1543e23e5 1046 }
nixnax 142:54d1543e23e5 1047
nixnax 142:54d1543e23e5 1048 /// handle an incoming TCP packet
nixnax 142:54d1543e23e5 1049 void TCPpacket()
nixnax 142:54d1543e23e5 1050 {
nixnax 142:54d1543e23e5 1051 dumpHeaderIP(0); // dump incoming packet header
nixnax 142:54d1543e23e5 1052 dumpHeaderTCP(0); // dump incoming packet header
nixnax 142:54d1543e23e5 1053 if (v2) dumpDataTCP();
nixnax 142:54d1543e23e5 1054 tcpHandler();
nixnax 142:54d1543e23e5 1055 }
nixnax 142:54d1543e23e5 1056
nixnax 142:54d1543e23e5 1057 /// handle the remaining IP protocols by ignoring them
nixnax 142:54d1543e23e5 1058 void otherProtocol()
nixnax 142:54d1543e23e5 1059 {
nixnax 142:54d1543e23e5 1060 debugPrintf("Other IP protocol");
nixnax 142:54d1543e23e5 1061 }
nixnax 142:54d1543e23e5 1062
nixnax 142:54d1543e23e5 1063 /// process an incoming IP packet
nixnax 142:54d1543e23e5 1064 void IPframe()
nixnax 142:54d1543e23e5 1065 {
nixnax 142:54d1543e23e5 1066 int protocol = ppp.pkt.buf[13];
nixnax 142:54d1543e23e5 1067 switch (protocol) {
nixnax 142:54d1543e23e5 1068 case 1:
nixnax 142:54d1543e23e5 1069 ICMPpacket();
nixnax 142:54d1543e23e5 1070 break;
nixnax 142:54d1543e23e5 1071 case 2:
nixnax 142:54d1543e23e5 1072 IGMPpacket();
nixnax 142:54d1543e23e5 1073 break;
nixnax 142:54d1543e23e5 1074 case 17:
nixnax 142:54d1543e23e5 1075 UDPpacket();
nixnax 142:54d1543e23e5 1076 break;
nixnax 142:54d1543e23e5 1077 case 6:
nixnax 142:54d1543e23e5 1078 TCPpacket();
nixnax 142:54d1543e23e5 1079 break;
nixnax 142:54d1543e23e5 1080 default:
nixnax 142:54d1543e23e5 1081 otherProtocol();
nixnax 142:54d1543e23e5 1082 }
nixnax 142:54d1543e23e5 1083 }
nixnax 142:54d1543e23e5 1084
nixnax 142:54d1543e23e5 1085 /// respond to LCP (line configuration protocol) configuration request) by allowing no options
nixnax 142:54d1543e23e5 1086 void LCPconfReq()
nixnax 142:54d1543e23e5 1087 {
nixnax 142:54d1543e23e5 1088 debugPrintf("LCP Config ");
nixnax 142:54d1543e23e5 1089 if (ppp.pkt.buf[7] != 4) {
nixnax 142:54d1543e23e5 1090 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax 142:54d1543e23e5 1091 debugPrintf("Reject\n");
nixnax 144:01d98cf7738e 1092 sendPppFrame();
nixnax 142:54d1543e23e5 1093 } else {
nixnax 142:54d1543e23e5 1094 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 142:54d1543e23e5 1095 debugPrintf("Ack\n");
nixnax 144:01d98cf7738e 1096 sendPppFrame();
nixnax 142:54d1543e23e5 1097 debugPrintf("LCP Ask\n");
nixnax 142:54d1543e23e5 1098 ppp.pkt.buf[4]=1; // request no options
nixnax 144:01d98cf7738e 1099 sendPppFrame();
nixnax 142:54d1543e23e5 1100 }
nixnax 142:54d1543e23e5 1101 }
nixnax 142:54d1543e23e5 1102
nixnax 142:54d1543e23e5 1103 /// handle LCP acknowledge packets by ignoring them
nixnax 142:54d1543e23e5 1104 void LCPconfAck()
nixnax 142:54d1543e23e5 1105 {
nixnax 142:54d1543e23e5 1106 debugPrintf("LCP Ack\n");
nixnax 142:54d1543e23e5 1107 }
nixnax 142:54d1543e23e5 1108
nixnax 143:c5019f856a56 1109 /// handle LCP end (disconnect) packets by acknowledging them and by setting ppp.online to false
nixnax 142:54d1543e23e5 1110 void LCPend()
nixnax 142:54d1543e23e5 1111 {
nixnax 142:54d1543e23e5 1112 ppp.pkt.buf[4]=6;
nixnax 144:01d98cf7738e 1113 sendPppFrame(); // acknowledge
nixnax 142:54d1543e23e5 1114 ppp.online=0; // start hunting for connect string again
nixnax 142:54d1543e23e5 1115 pppInitStruct(); // flush the receive buffer
nixnax 143:c5019f856a56 1116 debugPrintf("LCP End (Disconnect from host)\n");
nixnax 142:54d1543e23e5 1117 }
nixnax 142:54d1543e23e5 1118
nixnax 142:54d1543e23e5 1119 /// respond to other LCP requests by ignoring them
nixnax 142:54d1543e23e5 1120 void LCPother()
nixnax 142:54d1543e23e5 1121 {
nixnax 142:54d1543e23e5 1122 debugPrintf("LCP Other\n");
nixnax 142:54d1543e23e5 1123 dumpPPPFrame();
nixnax 142:54d1543e23e5 1124 }
nixnax 142:54d1543e23e5 1125
nixnax 142:54d1543e23e5 1126 /// process incoming LCP packets
nixnax 142:54d1543e23e5 1127 void LCPframe()
nixnax 142:54d1543e23e5 1128 {
nixnax 142:54d1543e23e5 1129 int code = ppp.pkt.buf[4];
nixnax 142:54d1543e23e5 1130 switch (code) {
nixnax 142:54d1543e23e5 1131 case 1:
nixnax 142:54d1543e23e5 1132 LCPconfReq();
nixnax 142:54d1543e23e5 1133 break; // config request
nixnax 142:54d1543e23e5 1134 case 2:
nixnax 142:54d1543e23e5 1135 LCPconfAck();
nixnax 142:54d1543e23e5 1136 break; // config ack
nixnax 142:54d1543e23e5 1137 case 5:
nixnax 142:54d1543e23e5 1138 LCPend();
nixnax 142:54d1543e23e5 1139 break; // end connection
nixnax 142:54d1543e23e5 1140 default:
nixnax 142:54d1543e23e5 1141 LCPother();
nixnax 142:54d1543e23e5 1142 }
nixnax 142:54d1543e23e5 1143 }
nixnax 142:54d1543e23e5 1144
nixnax 142:54d1543e23e5 1145 /// discard packets that are not IP, IPCP, or LCP
nixnax 142:54d1543e23e5 1146 void discardedFrame()
nixnax 142:54d1543e23e5 1147 {
nixnax 142:54d1543e23e5 1148 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 1149 }
nixnax 142:54d1543e23e5 1150
nixnax 142:54d1543e23e5 1151 /// determine the packet type (IP, IPCP or LCP) of incoming packets
nixnax 142:54d1543e23e5 1152 void determinePacketType()
nixnax 142:54d1543e23e5 1153 {
nixnax 142:54d1543e23e5 1154 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 142:54d1543e23e5 1155 debugPrintf("byte0 != ff\n");
nixnax 142:54d1543e23e5 1156 return;
nixnax 142:54d1543e23e5 1157 }
nixnax 142:54d1543e23e5 1158 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 142:54d1543e23e5 1159 debugPrintf("byte1 != 3\n");
nixnax 142:54d1543e23e5 1160 return;
nixnax 142:54d1543e23e5 1161 }
nixnax 142:54d1543e23e5 1162 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 142:54d1543e23e5 1163 debugPrintf("byte2 != 21\n");
nixnax 142:54d1543e23e5 1164 return;
nixnax 142:54d1543e23e5 1165 }
nixnax 142:54d1543e23e5 1166 int packetType = ppp.pkt.buf[2];
nixnax 142:54d1543e23e5 1167 switch (packetType) {
nixnax 142:54d1543e23e5 1168 case 0xc0:
nixnax 142:54d1543e23e5 1169 LCPframe();
nixnax 142:54d1543e23e5 1170 break; // link control
nixnax 142:54d1543e23e5 1171 case 0x80:
nixnax 142:54d1543e23e5 1172 IPCPframe();
nixnax 142:54d1543e23e5 1173 break; // IP control
nixnax 142:54d1543e23e5 1174 case 0x00:
nixnax 142:54d1543e23e5 1175 IPframe();
nixnax 142:54d1543e23e5 1176 break; // IP itself
nixnax 142:54d1543e23e5 1177 default:
nixnax 142:54d1543e23e5 1178 discardedFrame();
nixnax 142:54d1543e23e5 1179 }
nixnax 142:54d1543e23e5 1180 }
nixnax 142:54d1543e23e5 1181
nixnax 146:a45f49a2b29c 1182 /// a sniffer tool to assist in figuring out where in the code we are having characters in the input buffer
nixnax 146:a45f49a2b29c 1183 void sniff()
nixnax 146:a45f49a2b29c 1184 {
nixnax 146:a45f49a2b29c 1185 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 1186 }
nixnax 146:a45f49a2b29c 1187
nixnax 142:54d1543e23e5 1188 /// scan the PPP serial input stream for frame start markers
nixnax 143:c5019f856a56 1189 void waitForPppFrame()
nixnax 142:54d1543e23e5 1190 {
nixnax 142:54d1543e23e5 1191 while(1) {
nixnax 142:54d1543e23e5 1192 checkPc(); // handle received characters
nixnax 142:54d1543e23e5 1193 if ( ppp.rx.head != ppp.rx.tail ) {
nixnax 142:54d1543e23e5 1194 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 142:54d1543e23e5 1195 int rx = pc_getBuf(); // get the character
nixnax 142:54d1543e23e5 1196 if (rx==FRAME_7E) {
nixnax 142:54d1543e23e5 1197 if (ppp.firstFrame) { // is this the start of the first frame start
nixnax 142:54d1543e23e5 1198 ppp.firstFrame=0;
nixnax 142:54d1543e23e5 1199 ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax 142:54d1543e23e5 1200 ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where first frame started
nixnax 142:54d1543e23e5 1201 } else {
nixnax 142:54d1543e23e5 1202 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 142:54d1543e23e5 1203 processPPPFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 142:54d1543e23e5 1204 ppp.rx.rtail = ppp.rx.tail; // update real-time tail with the virtual tail
nixnax 142:54d1543e23e5 1205 ppp.hdlc.frameStartIndex = ppp.rx.tail; // remember where next frame started
nixnax 142:54d1543e23e5 1206 break;
nixnax 142:54d1543e23e5 1207 }
nixnax 142:54d1543e23e5 1208 }
nixnax 142:54d1543e23e5 1209 }
nixnax 142:54d1543e23e5 1210 }
nixnax 142:54d1543e23e5 1211 }
nixnax 142:54d1543e23e5 1212
nixnax 153:7993def8663f 1213 /// Wait for a dial-up modem connect command ("CLIENT") from the host PC, if found, we set ppp.online to true, which will start the IP packet scanner.
nixnax 153:7993def8663f 1214 // Note: a 0x7E in the input stream (ppp start of frame character) will also set ppp.online to true - see checkPc();
nixnax 153:7993def8663f 1215 void waitForPcConnectString()
nixnax 142:54d1543e23e5 1216 {
nixnax 142:54d1543e23e5 1217 while(ppp.online == 0) {
nixnax 142:54d1543e23e5 1218 checkPc(); // gather received characters
nixnax 142:54d1543e23e5 1219 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 142:54d1543e23e5 1220 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax 142:54d1543e23e5 1221 if (found1 != NULL) {
nixnax 142:54d1543e23e5 1222 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 143:c5019f856a56 1223 if (v0) debugPrintf("Connected: Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax 142:54d1543e23e5 1224 pc.puts("CLIENTSERVER");
nixnax 142:54d1543e23e5 1225 ppp.online=1; // we are connected - set flag so we stop looking for the connect string
nixnax 142:54d1543e23e5 1226 checkPc();
nixnax 142:54d1543e23e5 1227 }
nixnax 142:54d1543e23e5 1228 }
nixnax 142:54d1543e23e5 1229 }
nixnax 142:54d1543e23e5 1230
nixnax 144:01d98cf7738e 1231 /// Initialize PPP data structure and set serial port(s) baud rate(s)
nixnax 144:01d98cf7738e 1232 void initializePpp()
nixnax 142:54d1543e23e5 1233 {
nixnax 142:54d1543e23e5 1234 pc.baud(115200); // USB serial port to pc
nixnax 144:01d98cf7738e 1235 debugBaudRate(115200); // baud rate for (optional) debug serial port
nixnax 142:54d1543e23e5 1236 debugPrintf("\x1b[2J\x1b[H\x1b[30mmbed PPP-Blinky HTTP & WebSocket server ready :)\n"); // VT100 codes for clear_screen, home, black_text - Tera Term is a handy VT100 terminal
nixnax 142:54d1543e23e5 1237 pppInitStruct(); // initialize all the PPP properties
nixnax 143:c5019f856a56 1238 }