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@111:6a3b77c065c0, 2017-08-04 (annotated)

Committer:
nixnax
Date:
Fri Aug 04 20:59:40 2017 +0000
Revision:
111:6a3b77c065c0
Parent:
110:baec959e1915
Child:
112:30172f36bd33
Comments

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 108:f77ec4605945 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 94:8ee3eec2a2bb 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 110:baec959e1915 44 #if !defined(SERIAL_PORT_MONITOR_NO)
nixnax 88:b4a71242837c 45 #if defined(TARGET_LPC1768)
nixnax 85:53e57ff1cf05 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 110:baec959e1915 47 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE) || defined(TARGET_NUCLEO_L053R8) || defined(TARGET_NUCLEO_L476RG) || defined(TARGET_NUCLEO_F401RE)
nixnax 85:53e57ff1cf05 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 110:baec959e1915 49 #elif defined(TARGET_LPC11U24)
nixnax 110:baec959e1915 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 85:53e57ff1cf05 52 #error Add your target board's second serial port here if you want to use debugging - or choose SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 53 #endif
nixnax 85:53e57ff1cf05 54
nixnax 110:baec959e1915 55 #define debug(x...) xx.printf (x) /* if we have a serial port we print debug messages */
nixnax 85:53e57ff1cf05 56
nixnax 41:e58a5a09f411 57 #else
nixnax 110:baec959e1915 58 #define debug(x...) {} /* if we don't have a serial port we do nothing */
nixnax 41:e58a5a09f411 59 #endif
nixnax 41:e58a5a09f411 60
nixnax 110:baec959e1915 61 // verbosity flags used in debug printouts - change to 1 to see increasingly more detailed debug info.
nixnax 90:55e0f243a7ce 62 #define v0 0
nixnax 81:9ede60e9a2c8 63 #define v1 0
nixnax 77:abf92baebb42 64 #define v2 0
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 87:9f5ac1fabd95 101 unsigned int ident; // our IP ident value
nixnax 38:ab582987926e 102 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 103 int ledState; // state of LED1
nixnax 98:3babad0d1bd4 104 int httpPageCount;
nixnax 4:a469050d5b80 105 struct {
nixnax 105:45001195b325 106 #define RXBUFLEN (1<<11)
nixnax 93:9675adc36882 107 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 8192 bytes)
nixnax 85:53e57ff1cf05 108 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 93:9675adc36882 109 int head;
nixnax 93:9675adc36882 110 int tail;
nixnax 95:40af49390daf 111 int rtail;
nixnax 93:9675adc36882 112 int buflevel;
nixnax 38:ab582987926e 113 } rx; // serial port objects
nixnax 4:a469050d5b80 114 struct {
nixnax 38:ab582987926e 115 int len; // number of bytes in buffer
nixnax 38:ab582987926e 116 int crc; // PPP CRC (frame check)
nixnax 77:abf92baebb42 117 #define TCP_max_size 3300
nixnax 77:abf92baebb42 118 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 119 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 120 struct {
nixnax 50:ad4e7c3c88e5 121 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 122 int frameEndIndex; // frame end marker
nixnax 50:ad4e7c3c88e5 123 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 124 };
nixnax 31:e000c1b9c565 125
nixnax 29:30de79d658f6 126 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 127
nixnax 93:9675adc36882 128 // Initialize our global structure, clear the buffer, etc.
nixnax 29:30de79d658f6 129 void pppInitStruct()
nixnax 29:30de79d658f6 130 {
nixnax 81:9ede60e9a2c8 131 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 132 ppp.online=0;
nixnax 29:30de79d658f6 133 ppp.rx.tail=0;
nixnax 93:9675adc36882 134 ppp.rx.rtail=0;
nixnax 29:30de79d658f6 135 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 136 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 137 ppp.pkt.len=0;
nixnax 83:cdcb81d1910f 138 ppp.ident=1000;
nixnax 29:30de79d658f6 139 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 140 ppp.hdlc.frameStartIndex=0;
nixnax 98:3babad0d1bd4 141 ppp.httpPageCount=0;
nixnax 29:30de79d658f6 142 }
nixnax 26:11f4eb2663a7 143
nixnax 43:aa57db08995d 144 void led1Toggle()
nixnax 43:aa57db08995d 145 {
nixnax 43:aa57db08995d 146 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 93:9675adc36882 147 led1 = ppp.ledState; // toggle led
nixnax 43:aa57db08995d 148 }
nixnax 43:aa57db08995d 149
nixnax 29:30de79d658f6 150 void crcReset()
nixnax 29:30de79d658f6 151 {
nixnax 29:30de79d658f6 152 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 153 }
nixnax 4:a469050d5b80 154
nixnax 29:30de79d658f6 155 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 156 {
nixnax 29:30de79d658f6 157 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 158 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 159 x>>=1;
nixnax 29:30de79d658f6 160 }
nixnax 29:30de79d658f6 161 }
nixnax 29:30de79d658f6 162
nixnax 29:30de79d658f6 163 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 164 {
nixnax 31:e000c1b9c565 165 crcReset();
nixnax 31:e000c1b9c565 166 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 167 return ppp.crc;
nixnax 29:30de79d658f6 168 }
nixnax 0:2cf4880c312a 169
nixnax 85:53e57ff1cf05 170 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 171 void fillbuf()
nixnax 0:2cf4880c312a 172 {
nixnax 107:5fe806713d49 173 char ch;
nixnax 85:53e57ff1cf05 174 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 175 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 93:9675adc36882 176 if ( hd == ppp.rx.rtail ) {
nixnax 85:53e57ff1cf05 177 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 178 return;
nixnax 83:cdcb81d1910f 179 }
nixnax 107:5fe806713d49 180 ch = pc.getc(); // read new character
nixnax 107:5fe806713d49 181 ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax 107:5fe806713d49 182 if ( ppp.online == 0 ) {
nixnax 107:5fe806713d49 183 if (ch == 0x7E) {
nixnax 107:5fe806713d49 184 ppp.online = 1;
nixnax 107:5fe806713d49 185 debug("HDLC Frame (0x7E)\n");
nixnax 107:5fe806713d49 186 }
nixnax 107:5fe806713d49 187 }
nixnax 20:5db9b77b38a6 188 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 189 ppp.rx.buflevel++;
nixnax 15:b0154c910143 190 }
nixnax 0:2cf4880c312a 191 }
nixnax 0:2cf4880c312a 192
nixnax 85:53e57ff1cf05 193 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 194 {
nixnax 43:aa57db08995d 195 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 196 return emptyStatus;
nixnax 0:2cf4880c312a 197 }
nixnax 0:2cf4880c312a 198
nixnax 85:53e57ff1cf05 199 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 200 {
nixnax 63:9253b0e1b7d8 201 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 202 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 203 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 204 return x;
nixnax 0:2cf4880c312a 205 }
nixnax 0:2cf4880c312a 206
nixnax 95:40af49390daf 207 // Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 95:40af49390daf 208 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 95:40af49390daf 209 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 95:40af49390daf 210 void dumpPPPFrame()
nixnax 95:40af49390daf 211 {
nixnax 95:40af49390daf 212 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 95:40af49390daf 213 debug(" CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 95:40af49390daf 214 }
nixnax 95:40af49390daf 215
nixnax 50:ad4e7c3c88e5 216 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 217 {
nixnax 38:ab582987926e 218 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 219 if(start==end) {
nixnax 111:6a3b77c065c0 220 return; // empty frame
nixnax 29:30de79d658f6 221 }
nixnax 9:0992486d4a30 222 crcReset();
nixnax 9:0992486d4a30 223 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 224 ppp.pkt.len=0;
nixnax 9:0992486d4a30 225 int unstuff=0;
nixnax 17:4918c893d802 226 int idx = start;
nixnax 17:4918c893d802 227 while(1) {
nixnax 9:0992486d4a30 228 if (unstuff==0) {
nixnax 72:ad3d12753acf 229 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 230 else {
nixnax 72:ad3d12753acf 231 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 232 ppp.pkt.len++;
nixnax 29:30de79d658f6 233 dest++;
nixnax 72:ad3d12753acf 234 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 235 }
nixnax 66:f005b9fdf4d1 236 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 237 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 238 ppp.pkt.len++;
nixnax 29:30de79d658f6 239 dest++;
nixnax 72:ad3d12753acf 240 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 241 unstuff=0;
nixnax 9:0992486d4a30 242 }
nixnax 81:9ede60e9a2c8 243 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 244 if (idx == end) break;
nixnax 9:0992486d4a30 245 }
nixnax 29:30de79d658f6 246 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 247 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 248 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 249 determinePacketType();
nixnax 90:55e0f243a7ce 250 } else {
nixnax 111:6a3b77c065c0 251 if (0) { // don't normally report FCS because windows frequently early-terminates packets, and early-terminated packets all have FCS errors.
nixnax 95:40af49390daf 252 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 253 }
nixnax 9:0992486d4a30 254 }
nixnax 9:0992486d4a30 255 }
nixnax 9:0992486d4a30 256
nixnax 29:30de79d658f6 257 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 258 {
nixnax 29:30de79d658f6 259 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 260 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 261 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 262 } else {
nixnax 29:30de79d658f6 263 pc.putc(ch);
nixnax 29:30de79d658f6 264 }
nixnax 11:f58998c24f0b 265 }
nixnax 9:0992486d4a30 266
nixnax 93:9675adc36882 267 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 268 {
nixnax 17:4918c893d802 269 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 270 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 271 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 272 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 95:40af49390daf 273 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 274 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 93:9675adc36882 275 }
nixnax 16:cb0b80c24ba2 276 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 277 }
nixnax 9:0992486d4a30 278
nixnax 93:9675adc36882 279 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 280 {
nixnax 93:9675adc36882 281 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 282 ppp.pkt.buf[4]=2; // change code to ack
nixnax 108:f77ec4605945 283 send_pppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax 106:d14e6b597ca3 284
nixnax 107:5fe806713d49 285 debug("Our IPCP Ask (no options)\n");
nixnax 92:cb962b365cce 286 ppp.pkt.buf[4]=1; // change code to request
nixnax 106:d14e6b597ca3 287 ppp.pkt.buf[7]=4; // no options in this request
nixnax 106:d14e6b597ca3 288 ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax 103:4f5512dd11cf 289 send_pppFrame(); // send our request
nixnax 9:0992486d4a30 290 }
nixnax 9:0992486d4a30 291
nixnax 93:9675adc36882 292 void ipcpAckHandler()
nixnax 29:30de79d658f6 293 {
nixnax 93:9675adc36882 294 debug("Their IPCP Grant\n");
nixnax 29:30de79d658f6 295 }
nixnax 9:0992486d4a30 296
nixnax 93:9675adc36882 297 void ipcpNackHandler()
nixnax 29:30de79d658f6 298 {
nixnax 106:d14e6b597ca3 299 debug("Their IPCP Nack, Our ACK\n");
nixnax 107:5fe806713d49 300 if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax 106:d14e6b597ca3 301 ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax 106:d14e6b597ca3 302 send_pppFrame(); // let's request this IP address as ours
nixnax 106:d14e6b597ca3 303 } // if it's not an IP nack we ignore it
nixnax 29:30de79d658f6 304 }
nixnax 9:0992486d4a30 305
nixnax 93:9675adc36882 306 void ipcpDefaultHandler()
nixnax 29:30de79d658f6 307 {
nixnax 93:9675adc36882 308 debug("Their IPCP Other\n");
nixnax 29:30de79d658f6 309 }
nixnax 29:30de79d658f6 310
nixnax 29:30de79d658f6 311 void IPCPframe()
nixnax 29:30de79d658f6 312 {
nixnax 9:0992486d4a30 313 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 314 switch (code) {
nixnax 29:30de79d658f6 315 case 1:
nixnax 93:9675adc36882 316 ipcpConfigRequestHandler();
nixnax 29:30de79d658f6 317 break;
nixnax 29:30de79d658f6 318 case 2:
nixnax 93:9675adc36882 319 ipcpAckHandler();
nixnax 29:30de79d658f6 320 break;
nixnax 29:30de79d658f6 321 case 3:
nixnax 93:9675adc36882 322 ipcpNackHandler();
nixnax 29:30de79d658f6 323 break;
nixnax 29:30de79d658f6 324 default:
nixnax 93:9675adc36882 325 ipcpDefaultHandler();
nixnax 9:0992486d4a30 326 }
nixnax 29:30de79d658f6 327 }
nixnax 9:0992486d4a30 328
nixnax 29:30de79d658f6 329 void UDPpacket()
nixnax 29:30de79d658f6 330 {
nixnax 12:db0dc91f0231 331 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 332 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 333 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 334 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 335 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 336 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 337 #endif
nixnax 12:db0dc91f0231 338 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 339 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 340 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 341 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 342 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 343 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 344 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 345 #endif
nixnax 29:30de79d658f6 346 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 347 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 348 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 349 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 350 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 351 int printSize = udpLength;
nixnax 29:30de79d658f6 352 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 353 if (v1) {
nixnax 29:30de79d658f6 354 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 355 char ch = udpInf[i];
nixnax 29:30de79d658f6 356 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 357 debug("%c", ch);
nixnax 29:30de79d658f6 358 } else {
nixnax 64:677b9713a120 359 debug("_");
nixnax 29:30de79d658f6 360 }
nixnax 29:30de79d658f6 361 }
nixnax 29:30de79d658f6 362 }
nixnax 83:cdcb81d1910f 363 if (v0) debug("\n");
nixnax 12:db0dc91f0231 364 }
nixnax 11:f58998c24f0b 365
nixnax 76:00e208cceb8b 366 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 367 {
nixnax 77:abf92baebb42 368
nixnax 75:0d513869231f 369 unsigned int sum=0;
nixnax 76:00e208cceb8b 370 unsigned char placeHolder;
nixnax 29:30de79d658f6 371 if (len&1) {
nixnax 76:00e208cceb8b 372 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 373 ptr[len]=0;
nixnax 29:30de79d658f6 374 }
nixnax 29:30de79d658f6 375 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 376 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 377 ptr++;
nixnax 76:00e208cceb8b 378 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 379 ptr++;
nixnax 76:00e208cceb8b 380 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 381 sum = sum + val;
nixnax 11:f58998c24f0b 382 }
nixnax 29:30de79d658f6 383 if (len&1) {
nixnax 76:00e208cceb8b 384 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 385 }
nixnax 76:00e208cceb8b 386 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 387 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 388 return ~sum;
nixnax 29:30de79d658f6 389 }
nixnax 11:f58998c24f0b 390
nixnax 29:30de79d658f6 391 void headerCheckSum()
nixnax 29:30de79d658f6 392 {
nixnax 11:f58998c24f0b 393 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 394 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 395 int sum=0;
nixnax 11:f58998c24f0b 396
nixnax 29:30de79d658f6 397 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 398 int hi = *ptr;
nixnax 29:30de79d658f6 399 ptr++;
nixnax 29:30de79d658f6 400 int lo = *ptr;
nixnax 29:30de79d658f6 401 ptr++;
nixnax 11:f58998c24f0b 402 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 403 sum = sum + val;
nixnax 11:f58998c24f0b 404 }
nixnax 11:f58998c24f0b 405 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 406 sum = ~sum;
nixnax 11:f58998c24f0b 407 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 408 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 409 }
nixnax 9:0992486d4a30 410
nixnax 29:30de79d658f6 411 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 412 {
nixnax 12:db0dc91f0231 413 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 414 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 415 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 416 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 417 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 418 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 419 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 420 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 421 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 422 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 423 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 424 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 425 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 426 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 427 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 428 #endif
nixnax 81:9ede60e9a2c8 429 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 430 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 431 char src[4];
nixnax 29:30de79d658f6 432 char dst[4];
nixnax 12:db0dc91f0231 433 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 434 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 435 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 436 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 437 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 438 chkSum[0]=0;
nixnax 29:30de79d658f6 439 chkSum[1]=0;
nixnax 12:db0dc91f0231 440 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 441 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 442 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 443 icmpSum[0]=0;
nixnax 29:30de79d658f6 444 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 445 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 446 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 447 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 448 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 449
nixnax 16:cb0b80c24ba2 450 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 451 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 452 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 453 if (v0) {
nixnax 29:30de79d658f6 454 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 455 char ch = icmpData[i];
nixnax 29:30de79d658f6 456 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 457 debug("%c",ch);
nixnax 29:30de79d658f6 458 } else {
nixnax 64:677b9713a120 459 debug("_");
nixnax 29:30de79d658f6 460 }
nixnax 29:30de79d658f6 461 }
nixnax 64:677b9713a120 462 debug("\n");
nixnax 29:30de79d658f6 463 }
nixnax 93:9675adc36882 464 send_pppFrame(); // reply to the ping
nixnax 29:30de79d658f6 465
nixnax 12:db0dc91f0231 466 } else {
nixnax 29:30de79d658f6 467 if (v0) {
nixnax 42:4de44be70bfd 468 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 469 }
nixnax 11:f58998c24f0b 470 }
nixnax 11:f58998c24f0b 471 }
nixnax 11:f58998c24f0b 472
nixnax 29:30de79d658f6 473 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 474 {
nixnax 29:30de79d658f6 475 if (v0) {
nixnax 42:4de44be70bfd 476 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 477 }
nixnax 29:30de79d658f6 478 }
nixnax 11:f58998c24f0b 479
nixnax 29:30de79d658f6 480 void dumpHeaderIP ()
nixnax 29:30de79d658f6 481 {
nixnax 95:40af49390daf 482 if (v0) {
nixnax 95:40af49390daf 483 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 484 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 485 char * version = ipPkt; // top 4 bits
nixnax 95:40af49390daf 486 char * ihl = ipPkt; // bottom 4 bits
nixnax 95:40af49390daf 487 char * dscp = ipPkt+1; // top 6 bits
nixnax 95:40af49390daf 488 char * ecn = ipPkt+1; // lower 2 bits
nixnax 95:40af49390daf 489 char * pktLen = ipPkt+2; // 2 bytes
nixnax 95:40af49390daf 490 char * ident = ipPkt+4; // 2 bytes
nixnax 95:40af49390daf 491 char * flags = ipPkt+6; // 2 bits
nixnax 95:40af49390daf 492 char * ttl = ipPkt+8; // 1 byte
nixnax 95:40af49390daf 493 char * protocol = ipPkt+9; // 1 byte
nixnax 95:40af49390daf 494 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 495 #endif
nixnax 95:40af49390daf 496 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 95:40af49390daf 497 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 498
nixnax 55:43faae812be3 499 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 500 int versionIP = (version[0]>>4)&0xf;
nixnax 95:40af49390daf 501 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 95:40af49390daf 502 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 95:40af49390daf 503 int ecnIP = ecn[0]&3;
nixnax 95:40af49390daf 504 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 95:40af49390daf 505 int identIP = (ident[0]<<8)|ident[1];
nixnax 95:40af49390daf 506 int flagsIP = flags[0]>>14&3;
nixnax 95:40af49390daf 507 int ttlIP = ttl[0];
nixnax 95:40af49390daf 508 int protocolIP = protocol[0];
nixnax 95:40af49390daf 509 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 510 #endif
nixnax 55:43faae812be3 511
nixnax 95:40af49390daf 512 char srcIP [16];
nixnax 95:40af49390daf 513 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 95:40af49390daf 514 char dstIP [16];
nixnax 95:40af49390daf 515 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 95:40af49390daf 516 debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 95:40af49390daf 517 debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 95:40af49390daf 518 }
nixnax 29:30de79d658f6 519 }
nixnax 26:11f4eb2663a7 520
nixnax 29:30de79d658f6 521 void dumpHeaderTCP()
nixnax 29:30de79d658f6 522 {
nixnax 83:cdcb81d1910f 523 if( v0 ) {
nixnax 81:9ede60e9a2c8 524 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 525 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 526 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 527 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 528 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 529 #endif
nixnax 81:9ede60e9a2c8 530 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 531 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 532 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 533 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 534 #endif
nixnax 81:9ede60e9a2c8 535 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 536
nixnax 81:9ede60e9a2c8 537 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 538 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 539 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 540
nixnax 81:9ede60e9a2c8 541 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 542 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 543 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 544 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 545 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 546 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 547 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 548 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 549 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 550 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 551 }
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 89:2c8dd0c2a426 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 93:9675adc36882 696 int doFin = 0; // flag to see if we have to send an extra FIN message to shut down the link
nixnax 93:9675adc36882 697
nixnax 106:d14e6b597ca3 698 // A sparse TCP flag interpreter that implements stateless TCP connections
nixnax 77:abf92baebb42 699
nixnax 69:23f560087c16 700 switch ( flagsTCP ) {
nixnax 69:23f560087c16 701 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 702 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 703 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 704 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 705 break;
nixnax 77:abf92baebb42 706 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 98:3babad0d1bd4 707 if ( strncmp(tcpDataIn, "GET /", 5) == 0) { // check for an http GET command
nixnax 98:3babad0d1bd4 708 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing this TCP connection
nixnax 87:9f5ac1fabd95 709 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 98:3babad0d1bd4 710 } else {
nixnax 106:d14e6b597ca3 711 dataLen = tcpResponse(tcpDataOut,tcpDataSize); // not a web request, send a packet reporting number of received bytes
nixnax 69:23f560087c16 712 }
nixnax 69:23f560087c16 713 break;
nixnax 98:3babad0d1bd4 714 case TCP_FLAG_FIN | TCP_FLAG_PSH | TCP_FLAG_ACK:
nixnax 69:23f560087c16 715 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 93:9675adc36882 716 case TCP_FLAG_RST:
nixnax 85:53e57ff1cf05 717 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 718 break;
nixnax 98:3babad0d1bd4 719 case TCP_FLAG_FIN:
nixnax 98:3babad0d1bd4 720 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing the connection
nixnax 98:3babad0d1bd4 721 break;
nixnax 77:abf92baebb42 722 default:
nixnax 69:23f560087c16 723 return; // ignore remaining packets
nixnax 93:9675adc36882 724 } // switch
nixnax 77:abf92baebb42 725
nixnax 69:23f560087c16 726 // The TCP flag handling is now done
nixnax 105:45001195b325 727 // first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax 95:40af49390daf 728
nixnax 65:23b17c43aa0f 729 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 730 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 731 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 732 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 733
nixnax 60:2b770949c911 734 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 735 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 736 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 95:40af49390daf 737
nixnax 93:9675adc36882 738 sendTCP:
nixnax 106:d14e6b597ca3 739
nixnax 85:53e57ff1cf05 740 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 741 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 742 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 743 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 744
nixnax 85:53e57ff1cf05 745 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 746 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 747 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 748 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 749
nixnax 93:9675adc36882 750 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 751
nixnax 93:9675adc36882 752 // increment the ip ident number
nixnax 93:9675adc36882 753 ppp.ident++; // get next ident number for our packet
nixnax 93:9675adc36882 754 ident[0] = ppp.ident>>8;
nixnax 93:9675adc36882 755 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 756
nixnax 106:d14e6b597ca3 757 // Now we recalculate all the header sizes
nixnax 38:ab582987926e 758 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 759 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 760 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 761 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 762 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 763
nixnax 38:ab582987926e 764 // the header is all set up, now do the IP and TCP checksums
nixnax 61:b3c1a04efd0a 765 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 766 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 767 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 768
nixnax 64:677b9713a120 769 // 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 770 // 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 771
nixnax 87:9f5ac1fabd95 772 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 773 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 774 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 775 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 776 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 777 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 778 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 779
nixnax 61:b3c1a04efd0a 780 // pseudo-header built, now we can calculate TCP checksum
nixnax 29:30de79d658f6 781 checksumtcp[0]=0;
nixnax 29:30de79d658f6 782 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 783 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 784 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 785 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 786 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 95:40af49390daf 787
nixnax 93:9675adc36882 788 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 60:2b770949c911 789
nixnax 93:9675adc36882 790 if (doFin==1) { // they want to shut down the link, so we have to send another packet to close our side of the link
nixnax 93:9675adc36882 791 doFin=0;
nixnax 93:9675adc36882 792 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // tell them we are also finished
nixnax 93:9675adc36882 793 goto sendTCP; // send our final packet for this conversation.
nixnax 93:9675adc36882 794 }
nixnax 83:cdcb81d1910f 795 dumpHeaderIP();
nixnax 95:40af49390daf 796 dumpHeaderTCP();
nixnax 29:30de79d658f6 797 }
nixnax 26:11f4eb2663a7 798
nixnax 29:30de79d658f6 799 void dumpDataTCP()
nixnax 29:30de79d658f6 800 {
nixnax 26:11f4eb2663a7 801 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 802 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 803 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 804 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 805 if (v1) {
nixnax 42:4de44be70bfd 806 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 807 }
nixnax 29:30de79d658f6 808 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 809 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 810 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 811 }
nixnax 29:30de79d658f6 812 }
nixnax 26:11f4eb2663a7 813
nixnax 29:30de79d658f6 814 void TCPpacket()
nixnax 29:30de79d658f6 815 {
nixnax 83:cdcb81d1910f 816 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 817 dumpHeaderTCP();
nixnax 77:abf92baebb42 818 if (v2) {
nixnax 77:abf92baebb42 819 dumpDataTCP();
nixnax 77:abf92baebb42 820 }
nixnax 26:11f4eb2663a7 821 tcpHandler();
nixnax 11:f58998c24f0b 822 }
nixnax 11:f58998c24f0b 823
nixnax 29:30de79d658f6 824 void otherProtocol()
nixnax 29:30de79d658f6 825 {
nixnax 64:677b9713a120 826 debug("Other IP protocol");
nixnax 29:30de79d658f6 827 }
nixnax 26:11f4eb2663a7 828
nixnax 29:30de79d658f6 829 void IPframe()
nixnax 29:30de79d658f6 830 {
nixnax 10:74f8233f72c0 831 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 832 switch (protocol) {
nixnax 29:30de79d658f6 833 case 1:
nixnax 29:30de79d658f6 834 ICMPpacket();
nixnax 29:30de79d658f6 835 break;
nixnax 29:30de79d658f6 836 case 2:
nixnax 29:30de79d658f6 837 IGMPpacket();
nixnax 29:30de79d658f6 838 break;
nixnax 29:30de79d658f6 839 case 17:
nixnax 29:30de79d658f6 840 UDPpacket();
nixnax 29:30de79d658f6 841 break;
nixnax 29:30de79d658f6 842 case 6:
nixnax 29:30de79d658f6 843 TCPpacket();
nixnax 29:30de79d658f6 844 break;
nixnax 29:30de79d658f6 845 default:
nixnax 29:30de79d658f6 846 otherProtocol();
nixnax 29:30de79d658f6 847 }
nixnax 29:30de79d658f6 848 }
nixnax 9:0992486d4a30 849
nixnax 29:30de79d658f6 850 void LCPconfReq()
nixnax 29:30de79d658f6 851 {
nixnax 64:677b9713a120 852 debug("LCP Config ");
nixnax 9:0992486d4a30 853 if (ppp.pkt.buf[7] != 4) {
nixnax 111:6a3b77c065c0 854 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is default 1500 bytes
nixnax 64:677b9713a120 855 debug("Reject\n");
nixnax 93:9675adc36882 856 send_pppFrame();
nixnax 9:0992486d4a30 857 } else {
nixnax 9:0992486d4a30 858 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 859 debug("Ack\n");
nixnax 93:9675adc36882 860 send_pppFrame();
nixnax 64:677b9713a120 861 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 862 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 863 send_pppFrame();
nixnax 9:0992486d4a30 864 }
nixnax 9:0992486d4a30 865 }
nixnax 9:0992486d4a30 866
nixnax 29:30de79d658f6 867 void LCPconfAck()
nixnax 29:30de79d658f6 868 {
nixnax 64:677b9713a120 869 debug("LCP Ack\n");
nixnax 29:30de79d658f6 870 }
nixnax 9:0992486d4a30 871
nixnax 29:30de79d658f6 872 void LCPend()
nixnax 29:30de79d658f6 873 {
nixnax 29:30de79d658f6 874 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 875 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 876 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 877 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 878 debug("LCP End\n");
nixnax 9:0992486d4a30 879 }
nixnax 9:0992486d4a30 880
nixnax 29:30de79d658f6 881 void LCPother()
nixnax 29:30de79d658f6 882 {
nixnax 64:677b9713a120 883 debug("LCP Other\n");
nixnax 95:40af49390daf 884 dumpPPPFrame();
nixnax 29:30de79d658f6 885 }
nixnax 29:30de79d658f6 886
nixnax 29:30de79d658f6 887 void LCPframe()
nixnax 29:30de79d658f6 888 {
nixnax 29:30de79d658f6 889 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 890 switch (code) {
nixnax 29:30de79d658f6 891 case 1:
nixnax 29:30de79d658f6 892 LCPconfReq();
nixnax 29:30de79d658f6 893 break; // config request
nixnax 29:30de79d658f6 894 case 2:
nixnax 29:30de79d658f6 895 LCPconfAck();
nixnax 29:30de79d658f6 896 break; // config ack
nixnax 29:30de79d658f6 897 case 5:
nixnax 29:30de79d658f6 898 LCPend();
nixnax 29:30de79d658f6 899 break; // end connection
nixnax 29:30de79d658f6 900 default:
nixnax 29:30de79d658f6 901 LCPother();
nixnax 29:30de79d658f6 902 }
nixnax 9:0992486d4a30 903 }
nixnax 9:0992486d4a30 904
nixnax 29:30de79d658f6 905 void discardedFrame()
nixnax 29:30de79d658f6 906 {
nixnax 29:30de79d658f6 907 if (v0) {
nixnax 71:965619fedb3a 908 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 909 }
nixnax 9:0992486d4a30 910 }
nixnax 9:0992486d4a30 911
nixnax 29:30de79d658f6 912 void determinePacketType()
nixnax 29:30de79d658f6 913 {
nixnax 29:30de79d658f6 914 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 915 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 916 return;
nixnax 29:30de79d658f6 917 }
nixnax 29:30de79d658f6 918 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 919 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 920 return;
nixnax 29:30de79d658f6 921 }
nixnax 29:30de79d658f6 922 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 923 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 924 return;
nixnax 29:30de79d658f6 925 }
nixnax 9:0992486d4a30 926 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 927 switch (packetType) {
nixnax 29:30de79d658f6 928 case 0xc0:
nixnax 29:30de79d658f6 929 LCPframe();
nixnax 29:30de79d658f6 930 break; // link control
nixnax 29:30de79d658f6 931 case 0x80:
nixnax 29:30de79d658f6 932 IPCPframe();
nixnax 29:30de79d658f6 933 break; // IP control
nixnax 29:30de79d658f6 934 case 0x00:
nixnax 29:30de79d658f6 935 IPframe();
nixnax 29:30de79d658f6 936 break; // IP itself
nixnax 29:30de79d658f6 937 default:
nixnax 29:30de79d658f6 938 discardedFrame();
nixnax 9:0992486d4a30 939 }
nixnax 29:30de79d658f6 940 }
nixnax 9:0992486d4a30 941
nixnax 50:ad4e7c3c88e5 942 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 943 {
nixnax 85:53e57ff1cf05 944 while(1) {
nixnax 93:9675adc36882 945 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 946 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 947 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 948 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 949 if (rx==FRAME_7E) {
nixnax 106:d14e6b597ca3 950 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 107:5fe806713d49 951
nixnax 106:d14e6b597ca3 952 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 107:5fe806713d49 953
nixnax 106:d14e6b597ca3 954 ppp.rx.rtail = ppp.rx.tail;
nixnax 106:d14e6b597ca3 955 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 106:d14e6b597ca3 956 break;
nixnax 50:ad4e7c3c88e5 957 }
nixnax 50:ad4e7c3c88e5 958 }
nixnax 85:53e57ff1cf05 959 }
nixnax 50:ad4e7c3c88e5 960 }
nixnax 50:ad4e7c3c88e5 961
nixnax 29:30de79d658f6 962 void scanForConnectString()
nixnax 29:30de79d658f6 963 {
nixnax 81:9ede60e9a2c8 964 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 965 fillbuf();
nixnax 81:9ede60e9a2c8 966 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 106:d14e6b597ca3 967 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax 107:5fe806713d49 968 if (found1 != NULL) {
nixnax 107:5fe806713d49 969 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 107:5fe806713d49 970 led1Toggle();
nixnax 107:5fe806713d49 971 if (v0) debug("Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax 107:5fe806713d49 972 pc.puts("CLIENTSERVER");
nixnax 107:5fe806713d49 973 ppp.online=1; // we are connected, so we can stop looking for the connect string
nixnax 9:0992486d4a30 974 }
nixnax 9:0992486d4a30 975 }
nixnax 103:4f5512dd11cf 976 }
nixnax 81:9ede60e9a2c8 977
nixnax 9:0992486d4a30 978
nixnax 107:5fe806713d49 979
nixnax 107:5fe806713d49 980
nixnax 107:5fe806713d49 981
nixnax 110:baec959e1915 982
nixnax 111:6a3b77c065c0 983
nixnax 111:6a3b77c065c0 984
nixnax 0:2cf4880c312a 985 int main()
nixnax 0:2cf4880c312a 986 {
nixnax 14:c65831c25aaa 987 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 988 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 989 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 990 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 991 #endif
nixnax 9:0992486d4a30 992 pppInitStruct(); // initialize all the PPP properties
nixnax 0:2cf4880c312a 993 while(1) {
nixnax 51:a86d56844324 994 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 995 while(ppp.online) {
nixnax 81:9ede60e9a2c8 996 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 997 }
nixnax 7:ab147f5e97ac 998 }
nixnax 105:45001195b325 999 }