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.

main.cpp@117:c819ae068336, 2017-08-07 (annotated)

Committer:
nixnax
Date:
Mon Aug 07 15:06:25 2017 +0000
Revision:
117:c819ae068336
Parent:
116:1272e9f7ad70
Child:
118:54d1936e3768
Shortened IP debug dump. TCP send delay 20ms.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 93:9675adc36882 1 // PPP-Blinky - "The Most Basic Internet Of Things"
nixnax 0:2cf4880c312a 2
nixnax 93:9675adc36882 3 // A Tiny Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax 41:e58a5a09f411 4 // Also receives UDP packets and responds to ping (ICMP Echo requests)
nixnax 4:a469050d5b80 5
nixnax 93:9675adc36882 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 81:9ede60e9a2c8 7
nixnax 41:e58a5a09f411 8 // Notes and Instructions
nixnax 41:e58a5a09f411 9 // http://bit.ly/PPP-Blinky-Instructions
nixnax 114:8a5d70bbc1b2 10 // http://bit.ly/win-rasdial-config
nixnax 0:2cf4880c312a 11
nixnax 41:e58a5a09f411 12 // Handy reading material
nixnax 6:fba4c2e817b8 13 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 9:0992486d4a30 14 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 39:b90183d35f1e 15 // http://bit.ly/dialup777error - how to solve Dial Up Error 777 in Windows 7/8/10
nixnax 41:e58a5a09f411 16 // http://atari.kensclassics.org/wcomlog.htm
nixnax 6:fba4c2e817b8 17
nixnax 29:30de79d658f6 18 // Handy tools
nixnax 44:d0c61ae49ea5 19 // 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 109:644a59ebb5b1 20 // https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets
nixnax 29:30de79d658f6 21 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 95:40af49390daf 22 // 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 29:30de79d658f6 23 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 41:e58a5a09f411 24 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 91:5141ae9fba53 25 // 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 41:e58a5a09f411 26
nixnax 92:cb962b365cce 27 // Connecting PPP-Blinky to Linux
nixnax 93:9675adc36882 28 // PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax 93:9675adc36882 29 // pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax 92:cb962b365cce 30 // in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax 93:9675adc36882 31 // See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax 93:9675adc36882 32
nixnax 93:9675adc36882 33 // Ok, enough talking, time to check out some code!!
nixnax 106:d14e6b597ca3 34
nixnax 81:9ede60e9a2c8 35 #include "mbed.h"
nixnax 66:f005b9fdf4d1 36
nixnax 93:9675adc36882 37 // The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 38 // Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor this.
nixnax 110:baec959e1915 39 // Note - the LPC11U24 does NOT have a second serial port
nixnax 114:8a5d70bbc1b2 40 #define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax 0:2cf4880c312a 41
nixnax 93:9675adc36882 42 // here we define the OPTIONAL, second debug serial port for the various target boards
nixnax 93:9675adc36882 43 // insert your target board's port here if it's not in yet - if it works, please send it to me - thanks!!!
nixnax 114:8a5d70bbc1b2 44 #ifdef SERIAL_PORT_MONITOR_YES
nixnax 117:c819ae068336 45 #if defined(TARGET_LPC1768)
nixnax 117:c819ae068336 46 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 117:c819ae068336 47 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE) || defined(TARGET_NUCLEO_L053R8) || defined(TARGET_NUCLEO_L476RG) || defined(TARGET_NUCLEO_F401RE)
nixnax 117:c819ae068336 48 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 117:c819ae068336 49 #elif defined(TARGET_LPC11U24)
nixnax 117:c819ae068336 50 #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 85:53e57ff1cf05 51 #else
nixnax 117:c819ae068336 52 #error Add your target board's second serial port here if you want to use debugging - or choose SERIAL_PORT_MONITOR_NO
nixnax 117:c819ae068336 53 #endif
nixnax 117:c819ae068336 54 #define debug(x...) xx.printf (x) /* if we have a serial port we print debug messages */
nixnax 117:c819ae068336 55 #else
nixnax 117:c819ae068336 56 #define debug(x...) {} /* if we don't have a serial port we do nothing */
nixnax 41:e58a5a09f411 57 #endif
nixnax 41:e58a5a09f411 58
nixnax 110:baec959e1915 59 // verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax 112:30172f36bd33 60 #define v0 1
nixnax 81:9ede60e9a2c8 61 #define v1 0
nixnax 77:abf92baebb42 62 #define v2 0
nixnax 114:8a5d70bbc1b2 63 #define IP_HEADER_DUMP_YES /* YES for ip header dump */
nixnax 114:8a5d70bbc1b2 64 #define TCP_HEADER_DUMP_YES /* YES for tcp header dump */
nixnax 29:30de79d658f6 65
nixnax 93:9675adc36882 66 // this is the webpage we serve when we get an HTTP request to root (/)
nixnax 93:9675adc36882 67 // keep size under ~900 bytes to fit into a single PPP packet
nixnax 93:9675adc36882 68 const static char rootWebPage[] = "\
nixnax 66:f005b9fdf4d1 69 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 70 <html>\
nixnax 66:f005b9fdf4d1 71 <head>\
nixnax 66:f005b9fdf4d1 72 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 73 <script>\
nixnax 66:f005b9fdf4d1 74 window.onload=function(){\
nixnax 66:f005b9fdf4d1 75 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 76 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 77 </script>\
nixnax 66:f005b9fdf4d1 78 </head>\
nixnax 66:f005b9fdf4d1 79 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 80 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 81 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 82 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 83 </body>\
nixnax 69:23f560087c16 84 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 85
nixnax 73:2f56ec87dbe9 86 // The serial port on your mbed hardware. Your PC should be configured to view this port as a standard dial-up networking modem.
nixnax 73:2f56ec87dbe9 87 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 88 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 89 // See instructions at the top.
nixnax 73:2f56ec87dbe9 90 // 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 73:2f56ec87dbe9 91 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 92
nixnax 29:30de79d658f6 93 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 94
nixnax 66:f005b9fdf4d1 95 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 96 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 97
nixnax 29:30de79d658f6 98 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 99 struct pppType {
nixnax 38:ab582987926e 100 int online; // we hunt for a PPP connection if this is zero
nixnax 38:ab582987926e 101 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 102 int ledState; // state of LED1
nixnax 98:3babad0d1bd4 103 int httpPageCount;
nixnax 4:a469050d5b80 104 struct {
nixnax 105:45001195b325 105 #define RXBUFLEN (1<<11)
nixnax 117:c819ae068336 106 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 2048 bytes)
nixnax 85:53e57ff1cf05 107 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 93:9675adc36882 108 int head;
nixnax 93:9675adc36882 109 int tail;
nixnax 95:40af49390daf 110 int rtail;
nixnax 93:9675adc36882 111 int buflevel;
nixnax 38:ab582987926e 112 } rx; // serial port objects
nixnax 4:a469050d5b80 113 struct {
nixnax 38:ab582987926e 114 int len; // number of bytes in buffer
nixnax 38:ab582987926e 115 int crc; // PPP CRC (frame check)
nixnax 77:abf92baebb42 116 #define TCP_max_size 3300
nixnax 77:abf92baebb42 117 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 118 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 119 struct {
nixnax 50:ad4e7c3c88e5 120 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 121 int frameEndIndex; // frame end marker
nixnax 50:ad4e7c3c88e5 122 } hdlc; // hdlc frame objects
nixnax 114:8a5d70bbc1b2 123 struct {
nixnax 114:8a5d70bbc1b2 124 unsigned int ident; // our IP ident value (outgoing frame count)
nixnax 114:8a5d70bbc1b2 125 } ip; // ip related object
nixnax 29:30de79d658f6 126 };
nixnax 31:e000c1b9c565 127
nixnax 29:30de79d658f6 128 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 129
nixnax 93:9675adc36882 130 // Initialize our global structure, clear the buffer, etc.
nixnax 29:30de79d658f6 131 void pppInitStruct()
nixnax 29:30de79d658f6 132 {
nixnax 81:9ede60e9a2c8 133 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 134 ppp.online=0;
nixnax 29:30de79d658f6 135 ppp.rx.tail=0;
nixnax 93:9675adc36882 136 ppp.rx.rtail=0;
nixnax 29:30de79d658f6 137 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 138 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 139 ppp.pkt.len=0;
nixnax 114:8a5d70bbc1b2 140 ppp.ip.ident=10000; // easy to recognize in ip packet dumps
nixnax 29:30de79d658f6 141 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 142 ppp.hdlc.frameStartIndex=0;
nixnax 98:3babad0d1bd4 143 ppp.httpPageCount=0;
nixnax 29:30de79d658f6 144 }
nixnax 26:11f4eb2663a7 145
nixnax 43:aa57db08995d 146 void led1Toggle()
nixnax 43:aa57db08995d 147 {
nixnax 43:aa57db08995d 148 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 93:9675adc36882 149 led1 = ppp.ledState; // toggle led
nixnax 43:aa57db08995d 150 }
nixnax 43:aa57db08995d 151
nixnax 29:30de79d658f6 152 void crcReset()
nixnax 29:30de79d658f6 153 {
nixnax 29:30de79d658f6 154 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 155 }
nixnax 4:a469050d5b80 156
nixnax 29:30de79d658f6 157 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 158 {
nixnax 29:30de79d658f6 159 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 160 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 161 x>>=1;
nixnax 29:30de79d658f6 162 }
nixnax 29:30de79d658f6 163 }
nixnax 29:30de79d658f6 164
nixnax 29:30de79d658f6 165 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 166 {
nixnax 31:e000c1b9c565 167 crcReset();
nixnax 31:e000c1b9c565 168 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 169 return ppp.crc;
nixnax 29:30de79d658f6 170 }
nixnax 0:2cf4880c312a 171
nixnax 85:53e57ff1cf05 172 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 173 void fillbuf()
nixnax 0:2cf4880c312a 174 {
nixnax 107:5fe806713d49 175 char ch;
nixnax 85:53e57ff1cf05 176 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 177 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 93:9675adc36882 178 if ( hd == ppp.rx.rtail ) {
nixnax 85:53e57ff1cf05 179 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 180 return;
nixnax 83:cdcb81d1910f 181 }
nixnax 107:5fe806713d49 182 ch = pc.getc(); // read new character
nixnax 107:5fe806713d49 183 ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax 107:5fe806713d49 184 if ( ppp.online == 0 ) {
nixnax 107:5fe806713d49 185 if (ch == 0x7E) {
nixnax 107:5fe806713d49 186 ppp.online = 1;
nixnax 107:5fe806713d49 187 debug("HDLC Frame (0x7E)\n");
nixnax 114:8a5d70bbc1b2 188 }
nixnax 114:8a5d70bbc1b2 189 }
nixnax 20:5db9b77b38a6 190 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 191 ppp.rx.buflevel++;
nixnax 15:b0154c910143 192 }
nixnax 0:2cf4880c312a 193 }
nixnax 0:2cf4880c312a 194
nixnax 85:53e57ff1cf05 195 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 196 {
nixnax 43:aa57db08995d 197 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 198 return emptyStatus;
nixnax 0:2cf4880c312a 199 }
nixnax 0:2cf4880c312a 200
nixnax 85:53e57ff1cf05 201 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 202 {
nixnax 63:9253b0e1b7d8 203 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 204 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 205 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 206 return x;
nixnax 0:2cf4880c312a 207 }
nixnax 0:2cf4880c312a 208
nixnax 95:40af49390daf 209 // Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 95:40af49390daf 210 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 95:40af49390daf 211 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 95:40af49390daf 212 void dumpPPPFrame()
nixnax 95:40af49390daf 213 {
nixnax 95:40af49390daf 214 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 95:40af49390daf 215 debug(" CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 95:40af49390daf 216 }
nixnax 95:40af49390daf 217
nixnax 50:ad4e7c3c88e5 218 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 219 {
nixnax 38:ab582987926e 220 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 221 if(start==end) {
nixnax 111:6a3b77c065c0 222 return; // empty frame
nixnax 29:30de79d658f6 223 }
nixnax 9:0992486d4a30 224 crcReset();
nixnax 9:0992486d4a30 225 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 226 ppp.pkt.len=0;
nixnax 9:0992486d4a30 227 int unstuff=0;
nixnax 17:4918c893d802 228 int idx = start;
nixnax 17:4918c893d802 229 while(1) {
nixnax 9:0992486d4a30 230 if (unstuff==0) {
nixnax 72:ad3d12753acf 231 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 232 else {
nixnax 72:ad3d12753acf 233 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 234 ppp.pkt.len++;
nixnax 29:30de79d658f6 235 dest++;
nixnax 72:ad3d12753acf 236 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 237 }
nixnax 66:f005b9fdf4d1 238 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 239 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 240 ppp.pkt.len++;
nixnax 29:30de79d658f6 241 dest++;
nixnax 72:ad3d12753acf 242 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 243 unstuff=0;
nixnax 9:0992486d4a30 244 }
nixnax 81:9ede60e9a2c8 245 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 246 if (idx == end) break;
nixnax 9:0992486d4a30 247 }
nixnax 29:30de79d658f6 248 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 249 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 250 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 251 determinePacketType();
nixnax 90:55e0f243a7ce 252 } else {
nixnax 111:6a3b77c065c0 253 if (0) { // don't normally report FCS because windows frequently early-terminates packets, and early-terminated packets all have FCS errors.
nixnax 95:40af49390daf 254 debug("\nPPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // ignore packets with CRC errors but print a debug line
nixnax 95:40af49390daf 255 }
nixnax 9:0992486d4a30 256 }
nixnax 9:0992486d4a30 257 }
nixnax 9:0992486d4a30 258
nixnax 29:30de79d658f6 259 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 260 {
nixnax 29:30de79d658f6 261 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 262 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 263 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 264 } else {
nixnax 29:30de79d658f6 265 pc.putc(ch);
nixnax 29:30de79d658f6 266 }
nixnax 11:f58998c24f0b 267 }
nixnax 9:0992486d4a30 268
nixnax 93:9675adc36882 269 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 270 {
nixnax 17:4918c893d802 271 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 272 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 273 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 274 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 95:40af49390daf 275 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 276 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 93:9675adc36882 277 }
nixnax 16:cb0b80c24ba2 278 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 279 }
nixnax 9:0992486d4a30 280
nixnax 93:9675adc36882 281 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 282 {
nixnax 93:9675adc36882 283 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 284 ppp.pkt.buf[4]=2; // change code to ack
nixnax 108:f77ec4605945 285 send_pppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax 106:d14e6b597ca3 286
nixnax 107:5fe806713d49 287 debug("Our IPCP Ask (no options)\n");
nixnax 92:cb962b365cce 288 ppp.pkt.buf[4]=1; // change code to request
nixnax 106:d14e6b597ca3 289 ppp.pkt.buf[7]=4; // no options in this request
nixnax 106:d14e6b597ca3 290 ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax 103:4f5512dd11cf 291 send_pppFrame(); // send our request
nixnax 9:0992486d4a30 292 }
nixnax 9:0992486d4a30 293
nixnax 93:9675adc36882 294 void ipcpAckHandler()
nixnax 29:30de79d658f6 295 {
nixnax 93:9675adc36882 296 debug("Their IPCP Grant\n");
nixnax 29:30de79d658f6 297 }
nixnax 9:0992486d4a30 298
nixnax 93:9675adc36882 299 void ipcpNackHandler()
nixnax 29:30de79d658f6 300 {
nixnax 106:d14e6b597ca3 301 debug("Their IPCP Nack, Our ACK\n");
nixnax 107:5fe806713d49 302 if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax 106:d14e6b597ca3 303 ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax 106:d14e6b597ca3 304 send_pppFrame(); // let's request this IP address as ours
nixnax 106:d14e6b597ca3 305 } // if it's not an IP nack we ignore it
nixnax 29:30de79d658f6 306 }
nixnax 9:0992486d4a30 307
nixnax 93:9675adc36882 308 void ipcpDefaultHandler()
nixnax 29:30de79d658f6 309 {
nixnax 93:9675adc36882 310 debug("Their IPCP Other\n");
nixnax 29:30de79d658f6 311 }
nixnax 29:30de79d658f6 312
nixnax 29:30de79d658f6 313 void IPCPframe()
nixnax 29:30de79d658f6 314 {
nixnax 9:0992486d4a30 315 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 316 switch (code) {
nixnax 29:30de79d658f6 317 case 1:
nixnax 93:9675adc36882 318 ipcpConfigRequestHandler();
nixnax 29:30de79d658f6 319 break;
nixnax 29:30de79d658f6 320 case 2:
nixnax 93:9675adc36882 321 ipcpAckHandler();
nixnax 29:30de79d658f6 322 break;
nixnax 29:30de79d658f6 323 case 3:
nixnax 93:9675adc36882 324 ipcpNackHandler();
nixnax 29:30de79d658f6 325 break;
nixnax 29:30de79d658f6 326 default:
nixnax 93:9675adc36882 327 ipcpDefaultHandler();
nixnax 9:0992486d4a30 328 }
nixnax 29:30de79d658f6 329 }
nixnax 9:0992486d4a30 330
nixnax 29:30de79d658f6 331 void UDPpacket()
nixnax 29:30de79d658f6 332 {
nixnax 12:db0dc91f0231 333 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 334 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 335 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 336 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 337 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 338 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 339 #endif
nixnax 12:db0dc91f0231 340 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 341 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 342 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 343 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 344 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 345 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 346 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 347 #endif
nixnax 29:30de79d658f6 348 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 349 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 350 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 351 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 352 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 353 int printSize = udpLength;
nixnax 29:30de79d658f6 354 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 355 if (v1) {
nixnax 29:30de79d658f6 356 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 357 char ch = udpInf[i];
nixnax 29:30de79d658f6 358 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 359 debug("%c", ch);
nixnax 29:30de79d658f6 360 } else {
nixnax 64:677b9713a120 361 debug("_");
nixnax 29:30de79d658f6 362 }
nixnax 29:30de79d658f6 363 }
nixnax 29:30de79d658f6 364 }
nixnax 83:cdcb81d1910f 365 if (v0) debug("\n");
nixnax 12:db0dc91f0231 366 }
nixnax 11:f58998c24f0b 367
nixnax 76:00e208cceb8b 368 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 369 {
nixnax 75:0d513869231f 370 unsigned int sum=0;
nixnax 76:00e208cceb8b 371 unsigned char placeHolder;
nixnax 29:30de79d658f6 372 if (len&1) {
nixnax 76:00e208cceb8b 373 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 374 ptr[len]=0;
nixnax 29:30de79d658f6 375 }
nixnax 29:30de79d658f6 376 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 377 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 378 ptr++;
nixnax 76:00e208cceb8b 379 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 380 ptr++;
nixnax 76:00e208cceb8b 381 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 382 sum = sum + val;
nixnax 11:f58998c24f0b 383 }
nixnax 29:30de79d658f6 384 if (len&1) {
nixnax 76:00e208cceb8b 385 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 386 }
nixnax 76:00e208cceb8b 387 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 388 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 389 return ~sum;
nixnax 29:30de79d658f6 390 }
nixnax 11:f58998c24f0b 391
nixnax 29:30de79d658f6 392 void headerCheckSum()
nixnax 29:30de79d658f6 393 {
nixnax 11:f58998c24f0b 394 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 395 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 396 int sum=0;
nixnax 11:f58998c24f0b 397
nixnax 29:30de79d658f6 398 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 399 int hi = *ptr;
nixnax 29:30de79d658f6 400 ptr++;
nixnax 29:30de79d658f6 401 int lo = *ptr;
nixnax 29:30de79d658f6 402 ptr++;
nixnax 11:f58998c24f0b 403 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 404 sum = sum + val;
nixnax 11:f58998c24f0b 405 }
nixnax 11:f58998c24f0b 406 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 407 sum = ~sum;
nixnax 11:f58998c24f0b 408 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 409 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 410 }
nixnax 9:0992486d4a30 411
nixnax 29:30de79d658f6 412 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 413 {
nixnax 12:db0dc91f0231 414 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 415 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 416 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 417 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 418 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 419 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 420 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 421 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 422 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 423 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 424 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 425 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 426 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 427 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 428 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 429 #endif
nixnax 81:9ede60e9a2c8 430 if(v0) debug("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 81:9ede60e9a2c8 431 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 432 char src[4];
nixnax 29:30de79d658f6 433 char dst[4];
nixnax 12:db0dc91f0231 434 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 435 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 436 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 437 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 438 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 439 chkSum[0]=0;
nixnax 29:30de79d658f6 440 chkSum[1]=0;
nixnax 12:db0dc91f0231 441 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 442 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 443 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 444 icmpSum[0]=0;
nixnax 29:30de79d658f6 445 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 446 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 447 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 448 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 449 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 450
nixnax 16:cb0b80c24ba2 451 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 452 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 453 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 454 if (v0) {
nixnax 29:30de79d658f6 455 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 456 char ch = icmpData[i];
nixnax 29:30de79d658f6 457 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 458 debug("%c",ch);
nixnax 29:30de79d658f6 459 } else {
nixnax 64:677b9713a120 460 debug("_");
nixnax 29:30de79d658f6 461 }
nixnax 29:30de79d658f6 462 }
nixnax 64:677b9713a120 463 debug("\n");
nixnax 29:30de79d658f6 464 }
nixnax 93:9675adc36882 465 send_pppFrame(); // reply to the ping
nixnax 29:30de79d658f6 466
nixnax 12:db0dc91f0231 467 } else {
nixnax 29:30de79d658f6 468 if (v0) {
nixnax 42:4de44be70bfd 469 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 470 }
nixnax 11:f58998c24f0b 471 }
nixnax 11:f58998c24f0b 472 }
nixnax 11:f58998c24f0b 473
nixnax 29:30de79d658f6 474 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 475 {
nixnax 114:8a5d70bbc1b2 476 if (v0) debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 477 }
nixnax 11:f58998c24f0b 478
nixnax 114:8a5d70bbc1b2 479 void dumpHeaderIP (int outGoing)
nixnax 29:30de79d658f6 480 {
nixnax 114:8a5d70bbc1b2 481 #if defined(IP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax 114:8a5d70bbc1b2 482 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 114:8a5d70bbc1b2 483 char * ident = ipPkt+4; // 2 bytes
nixnax 114:8a5d70bbc1b2 484 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 114:8a5d70bbc1b2 485 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 114:8a5d70bbc1b2 486 #ifdef UNUSED_IP_VARIABLES
nixnax 114:8a5d70bbc1b2 487 char * version = ipPkt; // top 4 bits
nixnax 114:8a5d70bbc1b2 488 char * ihl = ipPkt; // bottom 4 bits
nixnax 114:8a5d70bbc1b2 489 char * dscp = ipPkt+1; // top 6 bits
nixnax 114:8a5d70bbc1b2 490 char * ecn = ipPkt+1; // lower 2 bits
nixnax 114:8a5d70bbc1b2 491 char * pktLen = ipPkt+2; // 2 bytes
nixnax 114:8a5d70bbc1b2 492 char * flags = ipPkt+6; // 2 bits
nixnax 114:8a5d70bbc1b2 493 char * ttl = ipPkt+8; // 1 byte
nixnax 114:8a5d70bbc1b2 494 char * protocol = ipPkt+9; // 1 byte
nixnax 114:8a5d70bbc1b2 495 char * headercheck= ipPkt+10; // 2 bytes
nixnax 114:8a5d70bbc1b2 496 int versionIP = (version[0]>>4)&0xf;
nixnax 114:8a5d70bbc1b2 497 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 114:8a5d70bbc1b2 498 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 114:8a5d70bbc1b2 499 int ecnIP = ecn[0]&3;
nixnax 114:8a5d70bbc1b2 500 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 114:8a5d70bbc1b2 501 int flagsIP = flags[0]>>14&3;
nixnax 114:8a5d70bbc1b2 502 int ttlIP = ttl[0];
nixnax 114:8a5d70bbc1b2 503 int protocolIP = protocol[0];
nixnax 114:8a5d70bbc1b2 504 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 63:9253b0e1b7d8 505 #endif
nixnax 114:8a5d70bbc1b2 506 int identIP = (ident[0]<<8)|ident[1];
nixnax 117:c819ae068336 507 #ifdef DUMP_FULL_IP_ADDRESS
nixnax 114:8a5d70bbc1b2 508 xx.printf("IP %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 114:8a5d70bbc1b2 509 #else
nixnax 114:8a5d70bbc1b2 510 xx.printf("IP %d %d ",srcAdr[3], dstAdr[3]); // short format - only least significant byte of the ip addresses
nixnax 55:43faae812be3 511 #endif
nixnax 114:8a5d70bbc1b2 512 xx.printf("Ident %05d ",identIP); // ident is a good way to correlate our dumps with net monitor or wireshark traces
nixnax 114:8a5d70bbc1b2 513 #ifndef TCP_HEADER_DUMP_YES
nixnax 114:8a5d70bbc1b2 514 xx.putc('\n'); // there is no TCP header dump, so terminate the line with \n
nixnax 114:8a5d70bbc1b2 515 #endif
nixnax 114:8a5d70bbc1b2 516 #endif
nixnax 29:30de79d658f6 517 }
nixnax 26:11f4eb2663a7 518
nixnax 114:8a5d70bbc1b2 519 void dumpHeaderTCP(int outGoing)
nixnax 29:30de79d658f6 520 {
nixnax 114:8a5d70bbc1b2 521 #if defined(TCP_HEADER_DUMP_YES) && defined(SERIAL_PORT_MONITOR_YES)
nixnax 114:8a5d70bbc1b2 522 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 114:8a5d70bbc1b2 523 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 114:8a5d70bbc1b2 524 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 114:8a5d70bbc1b2 525 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 114:8a5d70bbc1b2 526 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 114:8a5d70bbc1b2 527 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 114:8a5d70bbc1b2 528 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 114:8a5d70bbc1b2 529 if (seq && ack) {} // shut up the compiler about unused variables
nixnax 114:8a5d70bbc1b2 530 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 531
nixnax 114:8a5d70bbc1b2 532 char flagInfo[9]; // text string presentating the 8 most important TCP flags
nixnax 114:8a5d70bbc1b2 533 memset(flagInfo,'.', 8); // fill string with "........"
nixnax 114:8a5d70bbc1b2 534 flagInfo[8]=0; // null terminate string
nixnax 66:f005b9fdf4d1 535
nixnax 114:8a5d70bbc1b2 536 if (flags & (1<<0)) flagInfo[7]='F';
nixnax 114:8a5d70bbc1b2 537 if (flags & (1<<1)) flagInfo[6]='S';
nixnax 114:8a5d70bbc1b2 538 if (flags & (1<<2)) flagInfo[5]='R';
nixnax 114:8a5d70bbc1b2 539 if (flags & (1<<3)) flagInfo[4]='P';
nixnax 114:8a5d70bbc1b2 540 if (flags & (1<<4)) flagInfo[3]='A';
nixnax 114:8a5d70bbc1b2 541 if (flags & (1<<5)) flagInfo[2]='U';
nixnax 114:8a5d70bbc1b2 542 if (flags & (1<<6)) flagInfo[1]='E';
nixnax 114:8a5d70bbc1b2 543 if (flags & (1<<7)) flagInfo[0]='C';
nixnax 117:c819ae068336 544 #ifdef DUMP_IP_SEQUENCE_NUMBER
nixnax 114:8a5d70bbc1b2 545 xx.printf("%s Seq %10u\n", flagInfo, seq); // tcp flags and the sequence number
nixnax 117:c819ae068336 546 #else
nixnax 117:c819ae068336 547 xx.printf("%s\n", flagInfo); // tcp flags only
nixnax 117:c819ae068336 548 #endif
nixnax 114:8a5d70bbc1b2 549 if( (flags == (1<<4)) && outGoing ) // if this is a pure ack its probably then of the TCP link
nixnax 114:8a5d70bbc1b2 550 xx.putc('\n'); // so insert an extra line to mark the end of the conversation
nixnax 114:8a5d70bbc1b2 551 #endif
nixnax 29:30de79d658f6 552 }
nixnax 29:30de79d658f6 553
nixnax 68:0b74763ae67f 554 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 555 {
nixnax 67:a63e3486bcda 556 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 557 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 558 int contentLengthStart; // index where HTML starts
nixnax 93:9675adc36882 559 int xFetch, httpGetRoot; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 560
nixnax 98:3babad0d1bd4 561 ppp.httpPageCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 562
nixnax 98:3babad0d1bd4 563 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found GET, respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 564 xFetch = strncmp(dataStart, "GET /x", 6); // found GET /x , respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 565 // for example, in linux, xFetch can be used as: echo GET /x | nc 172.10.10.2
nixnax 93:9675adc36882 566 if( (httpGetRoot==0) || (xFetch==0) ) {
nixnax 115:b8ddff0e782f 567 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 568 } else {
nixnax 89:2c8dd0c2a426 569 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 570 }
nixnax 83:cdcb81d1910f 571 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 572 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 573 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 574 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 575 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 83:cdcb81d1910f 576 nHeader=n; // size of HTTP header
nixnax 93:9675adc36882 577 if( httpGetRoot == 0 ) {
nixnax 83:cdcb81d1910f 578 // this is where we insert our web page into the buffer
nixnax 93:9675adc36882 579 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 93:9675adc36882 580 n = n + sizeof(rootWebPage);
nixnax 85:53e57ff1cf05 581 } else {
nixnax 109:644a59ebb5b1 582 if (xFetch == 0) { // the page request started with "GET /x"
nixnax 89:2c8dd0c2a426 583
nixnax 89:2c8dd0c2a426 584 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 89:2c8dd0c2a426 585 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 89:2c8dd0c2a426 586 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 106:d14e6b597ca3 587 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed-ppp-blinky</title>"); // html title (W3C.org required elements)
nixnax 98:3babad0d1bd4 588 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.httpPageCount); // body = the http frame count
nixnax 89:2c8dd0c2a426 589 #else
nixnax 109:644a59ebb5b1 590 #define BENCHMARK_USING_BROWSER_NO /* set to _YES if you want to use your browser as a benchmark tool */
nixnax 98:3babad0d1bd4 591 #ifndef BENCHMARK_USING_BROWSER_NO
nixnax 109:644a59ebb5b1 592 // a small script that reloads the page after 10 ms - handy for benchmarking using your web browser, use http://172.10.10.2/x
nixnax 98:3babad0d1bd4 593 n=n+sprintf(n+dataStart, "<script>setTimeout(function(){location.reload();},10);</script><body>%d</body>",ppp.httpPageCount);
nixnax 98:3babad0d1bd4 594 #else
nixnax 98:3babad0d1bd4 595 n=n+sprintf(n+dataStart,"%d",ppp.httpPageCount); // not valid html but fast, most browsers and curl are ok with it
nixnax 98:3babad0d1bd4 596 #endif
nixnax 89:2c8dd0c2a426 597 #endif
nixnax 89:2c8dd0c2a426 598
nixnax 89:2c8dd0c2a426 599 } else {
nixnax 89:2c8dd0c2a426 600 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 89:2c8dd0c2a426 601 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky-mbed</title>"); // html title (required element)
nixnax 89:2c8dd0c2a426 602 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 89:2c8dd0c2a426 603 }
nixnax 83:cdcb81d1910f 604 }
nixnax 87:9f5ac1fabd95 605 while( (n%4)!= 2) n=n+sprintf(n+dataStart," "); // insert spaces until n is exactly two away from a multiple of four
nixnax 87:9f5ac1fabd95 606 n=n+sprintf(n+dataStart,"\r\n"); // add the last two characters (\r\n) - n is now an exact multiple of four
nixnax 87:9f5ac1fabd95 607
nixnax 83:cdcb81d1910f 608 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 609 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 610 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 611 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 612
nixnax 77:abf92baebb42 613 if (v2) {
nixnax 77:abf92baebb42 614 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 615 }
nixnax 67:a63e3486bcda 616 return n; // total byte size of our response
nixnax 67:a63e3486bcda 617 }
nixnax 67:a63e3486bcda 618
nixnax 98:3babad0d1bd4 619 // if not an http response we just report the number of bytes received
nixnax 98:3babad0d1bd4 620 // this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax 98:3babad0d1bd4 621 int tcpResponse(char * dataStart, int len)
nixnax 98:3babad0d1bd4 622 {
nixnax 98:3babad0d1bd4 623 int n=0; // number of bytes we have printed so far
nixnax 98:3babad0d1bd4 624 n=n+sprintf(n+dataStart,"Got %04d bytes.\n",len); // report the number of bytes received
nixnax 98:3babad0d1bd4 625 while( (n%4)!= 0) n=n+sprintf(n+dataStart,"*"); // insert spaces until n is exactly two away from a multiple of four
nixnax 98:3babad0d1bd4 626 if (v2) {
nixnax 98:3babad0d1bd4 627 debug("TCP response %d byes\n",n);
nixnax 98:3babad0d1bd4 628 }
nixnax 98:3babad0d1bd4 629 return n; // total byte size of our response
nixnax 98:3babad0d1bd4 630 }
nixnax 98:3babad0d1bd4 631
nixnax 29:30de79d658f6 632 void tcpHandler()
nixnax 29:30de79d658f6 633 {
nixnax 87:9f5ac1fabd95 634 // IP header
nixnax 87:9f5ac1fabd95 635
nixnax 26:11f4eb2663a7 636 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 637 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 638 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 639 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 640 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 641 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 642 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 643 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 644 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 645 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 646
nixnax 87:9f5ac1fabd95 647 // TCP header
nixnax 87:9f5ac1fabd95 648
nixnax 87:9f5ac1fabd95 649 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 650 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 651 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 652 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 653 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 654 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 655 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 656 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 657 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 658
nixnax 26:11f4eb2663a7 659 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 660 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 661 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 662
nixnax 87:9f5ac1fabd95 663 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 664 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 665 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 666
nixnax 85:53e57ff1cf05 667 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 668 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 669
nixnax 85:53e57ff1cf05 670 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 671 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 672
nixnax 29:30de79d658f6 673 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 674 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 675 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 676 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 677 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 678
nixnax 87:9f5ac1fabd95 679 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 680 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 681
nixnax 87:9f5ac1fabd95 682 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 683 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 684 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 685 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 686 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 687 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 688
nixnax 35:e7068df4d971 689 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 690 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 691 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 692
nixnax 111:6a3b77c065c0 693 windowsizetcp[0]=2; // tcp window size = 700
nixnax 97:bdf885e146dc 694 windowsizetcp[1]=0xbc; // tcp windows size = 700
nixnax 38:ab582987926e 695
nixnax 106:d14e6b597ca3 696 // A sparse TCP flag interpreter that implements stateless TCP connections
nixnax 77:abf92baebb42 697
nixnax 69:23f560087c16 698 switch ( flagsTCP ) {
nixnax 69:23f560087c16 699 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 700 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 114:8a5d70bbc1b2 701 seq_out = seq_in+0x10000000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 702 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 703 break;
nixnax 77:abf92baebb42 704 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 98:3babad0d1bd4 705 if ( strncmp(tcpDataIn, "GET /", 5) == 0) { // check for an http GET command
nixnax 117:c819ae068336 706 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax 87:9f5ac1fabd95 707 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 98:3babad0d1bd4 708 } else {
nixnax 106:d14e6b597ca3 709 dataLen = tcpResponse(tcpDataOut,tcpDataSize); // not a web request, send a packet reporting number of received bytes
nixnax 69:23f560087c16 710 }
nixnax 69:23f560087c16 711 break;
nixnax 116:1272e9f7ad70 712 case TCP_FLAG_FIN:
nixnax 116:1272e9f7ad70 713 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 98:3babad0d1bd4 714 case TCP_FLAG_FIN | TCP_FLAG_PSH | TCP_FLAG_ACK:
nixnax 117:c819ae068336 715 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set outgoing FIN flag to ask them to close from their side
nixnax 85:53e57ff1cf05 716 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 717 break;
nixnax 77:abf92baebb42 718 default:
nixnax 69:23f560087c16 719 return; // ignore remaining packets
nixnax 93:9675adc36882 720 } // switch
nixnax 77:abf92baebb42 721
nixnax 69:23f560087c16 722 // The TCP flag handling is now done
nixnax 105:45001195b325 723 // first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax 95:40af49390daf 724
nixnax 65:23b17c43aa0f 725 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 726 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 727 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 728 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 729
nixnax 60:2b770949c911 730 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 731 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 732 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 95:40af49390daf 733
nixnax 85:53e57ff1cf05 734 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 735 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 736 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 737 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 738
nixnax 85:53e57ff1cf05 739 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 740 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 741 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 742 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 743
nixnax 93:9675adc36882 744 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 745
nixnax 114:8a5d70bbc1b2 746 // increment our outgoing ip packet counter
nixnax 114:8a5d70bbc1b2 747 ppp.ip.ident++; // get next ident number for our packet
nixnax 114:8a5d70bbc1b2 748 ident[0] = ppp.ip.ident>>8;
nixnax 114:8a5d70bbc1b2 749 ident[1] = ppp.ip.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 750
nixnax 106:d14e6b597ca3 751 // Now we recalculate all the header sizes
nixnax 38:ab582987926e 752 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 753 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 754 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 755 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 756 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 757
nixnax 38:ab582987926e 758 // the header is all set up, now do the IP and TCP checksums
nixnax 61:b3c1a04efd0a 759 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 760 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 761 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 762
nixnax 64:677b9713a120 763 // now we have to build the so-called 12-byte TCP "pseudo-header" in front of the TCP header (containing some IP header values) in order to correctly calculate the TCP checksum
nixnax 63:9253b0e1b7d8 764 // this header contains the most important parts of the IP header, i.e. source and destination address, protocol number and data length.
nixnax 63:9253b0e1b7d8 765
nixnax 87:9f5ac1fabd95 766 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 767 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 768 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 769 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 770 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 771 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 772 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 773
nixnax 61:b3c1a04efd0a 774 // pseudo-header built, now we can calculate TCP checksum
nixnax 29:30de79d658f6 775 checksumtcp[0]=0;
nixnax 29:30de79d658f6 776 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 777 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 778 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 779 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 780 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 114:8a5d70bbc1b2 781 dumpHeaderIP(1); // dump outgoing IP header
nixnax 114:8a5d70bbc1b2 782 dumpHeaderTCP(1); // dump outgoing TCP header
nixnax 117:c819ae068336 783 wait_ms(20); // wait long enough to ensure we will be given time to dump the headers if we wanted to
nixnax 93:9675adc36882 784 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 29:30de79d658f6 785 }
nixnax 26:11f4eb2663a7 786
nixnax 29:30de79d658f6 787 void dumpDataTCP()
nixnax 29:30de79d658f6 788 {
nixnax 26:11f4eb2663a7 789 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 790 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 791 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 792 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 793 if (v1) {
nixnax 42:4de44be70bfd 794 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 795 }
nixnax 29:30de79d658f6 796 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 797 ppp.pkt.buf[4+ipHeaderLen+headerSizeTCP+dataLen]=0; // insert a null after the data so debug printf stops printing after the data
nixnax 42:4de44be70bfd 798 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 799 }
nixnax 29:30de79d658f6 800 }
nixnax 26:11f4eb2663a7 801
nixnax 29:30de79d658f6 802 void TCPpacket()
nixnax 29:30de79d658f6 803 {
nixnax 114:8a5d70bbc1b2 804 dumpHeaderIP(0); // dump incoming packet header
nixnax 114:8a5d70bbc1b2 805 dumpHeaderTCP(0); // dump incoming packet header
nixnax 77:abf92baebb42 806 if (v2) {
nixnax 77:abf92baebb42 807 dumpDataTCP();
nixnax 77:abf92baebb42 808 }
nixnax 26:11f4eb2663a7 809 tcpHandler();
nixnax 11:f58998c24f0b 810 }
nixnax 11:f58998c24f0b 811
nixnax 29:30de79d658f6 812 void otherProtocol()
nixnax 29:30de79d658f6 813 {
nixnax 64:677b9713a120 814 debug("Other IP protocol");
nixnax 29:30de79d658f6 815 }
nixnax 26:11f4eb2663a7 816
nixnax 29:30de79d658f6 817 void IPframe()
nixnax 29:30de79d658f6 818 {
nixnax 10:74f8233f72c0 819 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 820 switch (protocol) {
nixnax 29:30de79d658f6 821 case 1:
nixnax 29:30de79d658f6 822 ICMPpacket();
nixnax 29:30de79d658f6 823 break;
nixnax 29:30de79d658f6 824 case 2:
nixnax 29:30de79d658f6 825 IGMPpacket();
nixnax 29:30de79d658f6 826 break;
nixnax 29:30de79d658f6 827 case 17:
nixnax 29:30de79d658f6 828 UDPpacket();
nixnax 29:30de79d658f6 829 break;
nixnax 29:30de79d658f6 830 case 6:
nixnax 29:30de79d658f6 831 TCPpacket();
nixnax 29:30de79d658f6 832 break;
nixnax 29:30de79d658f6 833 default:
nixnax 29:30de79d658f6 834 otherProtocol();
nixnax 29:30de79d658f6 835 }
nixnax 29:30de79d658f6 836 }
nixnax 9:0992486d4a30 837
nixnax 29:30de79d658f6 838 void LCPconfReq()
nixnax 29:30de79d658f6 839 {
nixnax 64:677b9713a120 840 debug("LCP Config ");
nixnax 9:0992486d4a30 841 if (ppp.pkt.buf[7] != 4) {
nixnax 111:6a3b77c065c0 842 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax 64:677b9713a120 843 debug("Reject\n");
nixnax 93:9675adc36882 844 send_pppFrame();
nixnax 9:0992486d4a30 845 } else {
nixnax 9:0992486d4a30 846 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 847 debug("Ack\n");
nixnax 93:9675adc36882 848 send_pppFrame();
nixnax 64:677b9713a120 849 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 850 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 851 send_pppFrame();
nixnax 9:0992486d4a30 852 }
nixnax 9:0992486d4a30 853 }
nixnax 9:0992486d4a30 854
nixnax 29:30de79d658f6 855 void LCPconfAck()
nixnax 29:30de79d658f6 856 {
nixnax 64:677b9713a120 857 debug("LCP Ack\n");
nixnax 29:30de79d658f6 858 }
nixnax 9:0992486d4a30 859
nixnax 29:30de79d658f6 860 void LCPend()
nixnax 29:30de79d658f6 861 {
nixnax 29:30de79d658f6 862 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 863 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 864 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 865 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 866 debug("LCP End\n");
nixnax 9:0992486d4a30 867 }
nixnax 9:0992486d4a30 868
nixnax 29:30de79d658f6 869 void LCPother()
nixnax 29:30de79d658f6 870 {
nixnax 64:677b9713a120 871 debug("LCP Other\n");
nixnax 95:40af49390daf 872 dumpPPPFrame();
nixnax 29:30de79d658f6 873 }
nixnax 29:30de79d658f6 874
nixnax 29:30de79d658f6 875 void LCPframe()
nixnax 29:30de79d658f6 876 {
nixnax 29:30de79d658f6 877 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 878 switch (code) {
nixnax 29:30de79d658f6 879 case 1:
nixnax 29:30de79d658f6 880 LCPconfReq();
nixnax 29:30de79d658f6 881 break; // config request
nixnax 29:30de79d658f6 882 case 2:
nixnax 29:30de79d658f6 883 LCPconfAck();
nixnax 29:30de79d658f6 884 break; // config ack
nixnax 29:30de79d658f6 885 case 5:
nixnax 29:30de79d658f6 886 LCPend();
nixnax 29:30de79d658f6 887 break; // end connection
nixnax 29:30de79d658f6 888 default:
nixnax 29:30de79d658f6 889 LCPother();
nixnax 29:30de79d658f6 890 }
nixnax 9:0992486d4a30 891 }
nixnax 9:0992486d4a30 892
nixnax 29:30de79d658f6 893 void discardedFrame()
nixnax 29:30de79d658f6 894 {
nixnax 29:30de79d658f6 895 if (v0) {
nixnax 71:965619fedb3a 896 debug("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 29:30de79d658f6 897 }
nixnax 9:0992486d4a30 898 }
nixnax 9:0992486d4a30 899
nixnax 29:30de79d658f6 900 void determinePacketType()
nixnax 29:30de79d658f6 901 {
nixnax 29:30de79d658f6 902 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 903 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 904 return;
nixnax 29:30de79d658f6 905 }
nixnax 29:30de79d658f6 906 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 907 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 908 return;
nixnax 29:30de79d658f6 909 }
nixnax 29:30de79d658f6 910 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 911 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 912 return;
nixnax 29:30de79d658f6 913 }
nixnax 9:0992486d4a30 914 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 915 switch (packetType) {
nixnax 29:30de79d658f6 916 case 0xc0:
nixnax 29:30de79d658f6 917 LCPframe();
nixnax 29:30de79d658f6 918 break; // link control
nixnax 29:30de79d658f6 919 case 0x80:
nixnax 29:30de79d658f6 920 IPCPframe();
nixnax 29:30de79d658f6 921 break; // IP control
nixnax 29:30de79d658f6 922 case 0x00:
nixnax 29:30de79d658f6 923 IPframe();
nixnax 29:30de79d658f6 924 break; // IP itself
nixnax 29:30de79d658f6 925 default:
nixnax 29:30de79d658f6 926 discardedFrame();
nixnax 9:0992486d4a30 927 }
nixnax 29:30de79d658f6 928 }
nixnax 9:0992486d4a30 929
nixnax 50:ad4e7c3c88e5 930 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 931 {
nixnax 85:53e57ff1cf05 932 while(1) {
nixnax 93:9675adc36882 933 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 934 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 935 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 936 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 937 if (rx==FRAME_7E) {
nixnax 106:d14e6b597ca3 938 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 114:8a5d70bbc1b2 939
nixnax 106:d14e6b597ca3 940 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 114:8a5d70bbc1b2 941
nixnax 106:d14e6b597ca3 942 ppp.rx.rtail = ppp.rx.tail;
nixnax 106:d14e6b597ca3 943 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 106:d14e6b597ca3 944 break;
nixnax 50:ad4e7c3c88e5 945 }
nixnax 50:ad4e7c3c88e5 946 }
nixnax 85:53e57ff1cf05 947 }
nixnax 50:ad4e7c3c88e5 948 }
nixnax 50:ad4e7c3c88e5 949
nixnax 29:30de79d658f6 950 void scanForConnectString()
nixnax 29:30de79d658f6 951 {
nixnax 81:9ede60e9a2c8 952 while(ppp.online == 0) {
nixnax 114:8a5d70bbc1b2 953 fillbuf(); // gather received characters
nixnax 81:9ede60e9a2c8 954 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 106:d14e6b597ca3 955 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax 107:5fe806713d49 956 if (found1 != NULL) {
nixnax 107:5fe806713d49 957 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 107:5fe806713d49 958 if (v0) debug("Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax 107:5fe806713d49 959 pc.puts("CLIENTSERVER");
nixnax 107:5fe806713d49 960 ppp.online=1; // we are connected, so we can stop looking for the connect string
nixnax 9:0992486d4a30 961 }
nixnax 9:0992486d4a30 962 }
nixnax 103:4f5512dd11cf 963 }
nixnax 81:9ede60e9a2c8 964
nixnax 9:0992486d4a30 965
nixnax 107:5fe806713d49 966
nixnax 107:5fe806713d49 967
nixnax 107:5fe806713d49 968
nixnax 110:baec959e1915 969
nixnax 111:6a3b77c065c0 970
nixnax 111:6a3b77c065c0 971
nixnax 114:8a5d70bbc1b2 972
nixnax 114:8a5d70bbc1b2 973
nixnax 114:8a5d70bbc1b2 974
nixnax 114:8a5d70bbc1b2 975
nixnax 114:8a5d70bbc1b2 976
nixnax 114:8a5d70bbc1b2 977
nixnax 114:8a5d70bbc1b2 978
nixnax 114:8a5d70bbc1b2 979
nixnax 114:8a5d70bbc1b2 980
nixnax 114:8a5d70bbc1b2 981
nixnax 114:8a5d70bbc1b2 982
nixnax 114:8a5d70bbc1b2 983
nixnax 114:8a5d70bbc1b2 984
nixnax 114:8a5d70bbc1b2 985
nixnax 114:8a5d70bbc1b2 986
nixnax 114:8a5d70bbc1b2 987
nixnax 117:c819ae068336 988
nixnax 0:2cf4880c312a 989 int main()
nixnax 0:2cf4880c312a 990 {
nixnax 14:c65831c25aaa 991 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 992 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 993 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 994 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 995 #endif
nixnax 9:0992486d4a30 996 pppInitStruct(); // initialize all the PPP properties
nixnax 0:2cf4880c312a 997 while(1) {
nixnax 51:a86d56844324 998 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 999 while(ppp.online) {
nixnax 81:9ede60e9a2c8 1000 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 1001 }
nixnax 7:ab147f5e97ac 1002 }
nixnax 105:45001195b325 1003 }