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@81:9ede60e9a2c8, 2017-07-15 (annotated)

Committer:
nixnax
Date:
Sat Jul 15 20:50:13 2017 +0000
Revision:
81:9ede60e9a2c8
Parent:
80:753f5dd2e84e
Child:
82:051f77f7dd72
wait_for_HDLC logic change; only scan for connect string when offline

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 81:9ede60e9a2c8 1 // PPP-Blinky - "My Internet Of Thing"
nixnax 0:2cf4880c312a 2
nixnax 72:ad3d12753acf 3 // A Tiny Webserver Using Windows XP/7/8/10 Dial-Up Networking Over A Serial Port.
nixnax 0:2cf4880c312a 4
nixnax 41:e58a5a09f411 5 // Also receives UDP packets and responds to ping (ICMP Echo requests)
nixnax 4:a469050d5b80 6
nixnax 81:9ede60e9a2c8 7 // Copyright 2016 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 8
nixnax 41:e58a5a09f411 9 // Notes and Instructions
nixnax 41:e58a5a09f411 10 // http://bit.ly/PPP-Blinky-Instructions
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 44:d0c61ae49ea5 20 // Wireshark - can't monitor Dial-Up network packets on windows, but useful - can import our dumpFrame routine's hex output
nixnax 29:30de79d658f6 21 // Microsoft network monitor - real-time monitoring of all our packets
nixnax 29:30de79d658f6 22 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 29:30de79d658f6 23 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE)
nixnax 41:e58a5a09f411 24 // The curl.exe program in Windows Powershell - use it like this to stress test the webserver: while (1) { curl 172.10.10.1 }
nixnax 29:30de79d658f6 25 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 41:e58a5a09f411 26 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 41:e58a5a09f411 27
nixnax 81:9ede60e9a2c8 28 #include "mbed.h"
nixnax 66:f005b9fdf4d1 29
nixnax 66:f005b9fdf4d1 30 // The #define below enables/disables a SECOND (optional) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 31 // 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 81:9ede60e9a2c8 32 #define SERIAL_PORT_MONITOR_YES /* or change to SERIAL_PORT_MONITOR_YES */
nixnax 0:2cf4880c312a 33
nixnax 41:e58a5a09f411 34 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 66:f005b9fdf4d1 35 Serial xx(PC_10, PC_11); // Not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax 42:4de44be70bfd 36 #define debug(x...) xx.printf (x)
nixnax 41:e58a5a09f411 37 #else
nixnax 42:4de44be70bfd 38 #define debug(x...) {}
nixnax 41:e58a5a09f411 39 #endif
nixnax 41:e58a5a09f411 40
nixnax 66:f005b9fdf4d1 41 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 42 #define v0 0
nixnax 66:f005b9fdf4d1 43 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 44 #define v1 0
nixnax 77:abf92baebb42 45 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 77:abf92baebb42 46 #define v2 0
nixnax 29:30de79d658f6 47
nixnax 66:f005b9fdf4d1 48 // this is the webpage we serve when we get an HTTP request
nixnax 72:ad3d12753acf 49 // keep size under 900 bytes to fit into a single frame
nixnax 66:f005b9fdf4d1 50 const static char ourWebPage[] = "\
nixnax 66:f005b9fdf4d1 51 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 52 <html>\
nixnax 66:f005b9fdf4d1 53 <head>\
nixnax 66:f005b9fdf4d1 54 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 55 <script>\
nixnax 66:f005b9fdf4d1 56 window.onload=function(){\
nixnax 66:f005b9fdf4d1 57 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 58 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 59 </script>\
nixnax 66:f005b9fdf4d1 60 </head>\
nixnax 66:f005b9fdf4d1 61 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 62 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 63 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 64 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 65 </body>\
nixnax 69:23f560087c16 66 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 67
nixnax 69:23f560087c16 68
nixnax 66:f005b9fdf4d1 69
nixnax 73:2f56ec87dbe9 70 // 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 71 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 72 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 73 // See instructions at the top.
nixnax 73:2f56ec87dbe9 74 // 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 75 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 76
nixnax 29:30de79d658f6 77 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 78
nixnax 66:f005b9fdf4d1 79 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 80 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 81
nixnax 29:30de79d658f6 82 // the serial port receive buffer and packet buffer
nixnax 0:2cf4880c312a 83
nixnax 29:30de79d658f6 84 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 85 struct pppType {
nixnax 38:ab582987926e 86 int online; // we hunt for a PPP connection if this is zero
nixnax 38:ab582987926e 87 int ident; // our IP ident value
nixnax 38:ab582987926e 88 unsigned int seq; // our TCP sequence number
nixnax 38:ab582987926e 89 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 90 int ledState; // state of LED1
nixnax 4:a469050d5b80 91 struct {
nixnax 81:9ede60e9a2c8 92 #define RXBUFLEN (1<<14)
nixnax 81:9ede60e9a2c8 93 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in rxHandler
nixnax 72:ad3d12753acf 94 //char * buf;
nixnax 29:30de79d658f6 95 volatile int head;
nixnax 29:30de79d658f6 96 volatile int tail;
nixnax 81:9ede60e9a2c8 97 volatile int buflevel;
nixnax 38:ab582987926e 98 } rx; // serial port objects
nixnax 4:a469050d5b80 99 struct {
nixnax 38:ab582987926e 100 int len; // number of bytes in buffer
nixnax 38:ab582987926e 101 int crc; // PPP CRC (frame check)
nixnax 72:ad3d12753acf 102 //char * buf; // the actual buffer
nixnax 77:abf92baebb42 103 #define TCP_max_size 3300
nixnax 77:abf92baebb42 104 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 105 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 106 struct {
nixnax 50:ad4e7c3c88e5 107 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 108 int frameEndIndex; // frame end marker
nixnax 81:9ede60e9a2c8 109 int frameFound; // we have found at least one start of frame already
nixnax 50:ad4e7c3c88e5 110 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 111 };
nixnax 31:e000c1b9c565 112
nixnax 29:30de79d658f6 113 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 114
nixnax 60:2b770949c911 115 // Initialize our globals
nixnax 29:30de79d658f6 116 void pppInitStruct()
nixnax 29:30de79d658f6 117 {
nixnax 81:9ede60e9a2c8 118 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 119 ppp.online=0;
nixnax 81:9ede60e9a2c8 120 __disable_irq();
nixnax 29:30de79d658f6 121 ppp.rx.tail=0;
nixnax 29:30de79d658f6 122 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 123 __enable_irq();
nixnax 81:9ede60e9a2c8 124 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 125 ppp.pkt.len=0;
nixnax 29:30de79d658f6 126 ppp.ident=0;
nixnax 29:30de79d658f6 127 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 128 ppp.hdlc.frameFound=0;
nixnax 81:9ede60e9a2c8 129 ppp.hdlc.frameStartIndex=0;
nixnax 29:30de79d658f6 130 }
nixnax 26:11f4eb2663a7 131
nixnax 43:aa57db08995d 132 void led1Toggle()
nixnax 43:aa57db08995d 133 {
nixnax 43:aa57db08995d 134 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 43:aa57db08995d 135 led1 = ppp.ledState;
nixnax 43:aa57db08995d 136 }
nixnax 43:aa57db08995d 137
nixnax 29:30de79d658f6 138 void crcReset()
nixnax 29:30de79d658f6 139 {
nixnax 29:30de79d658f6 140 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 141 }
nixnax 4:a469050d5b80 142
nixnax 29:30de79d658f6 143 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 144 {
nixnax 29:30de79d658f6 145 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 146 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 147 x>>=1;
nixnax 29:30de79d658f6 148 }
nixnax 29:30de79d658f6 149 }
nixnax 29:30de79d658f6 150
nixnax 29:30de79d658f6 151 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 152 {
nixnax 31:e000c1b9c565 153 crcReset();
nixnax 31:e000c1b9c565 154 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 155 return ppp.crc;
nixnax 29:30de79d658f6 156 }
nixnax 0:2cf4880c312a 157
nixnax 0:2cf4880c312a 158 void rxHandler() // serial port receive interrupt handler
nixnax 0:2cf4880c312a 159 {
nixnax 17:4918c893d802 160 while ( pc.readable() ) {
nixnax 81:9ede60e9a2c8 161 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap
nixnax 20:5db9b77b38a6 162 if ( hd == ppp.rx.tail ) break; // watch for buffer full
nixnax 17:4918c893d802 163 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 164 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 165 ppp.rx.buflevel++;
nixnax 15:b0154c910143 166 }
nixnax 0:2cf4880c312a 167 }
nixnax 0:2cf4880c312a 168
nixnax 22:00df34cd4d7e 169 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 170 {
nixnax 22:00df34cd4d7e 171 __disable_irq(); // critical section start
nixnax 43:aa57db08995d 172 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 22:00df34cd4d7e 173 __enable_irq(); // critical section end
nixnax 43:aa57db08995d 174 return emptyStatus;
nixnax 0:2cf4880c312a 175 }
nixnax 0:2cf4880c312a 176
nixnax 0:2cf4880c312a 177 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 178 {
nixnax 63:9253b0e1b7d8 179 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 180 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 181 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 182 return x;
nixnax 0:2cf4880c312a 183 }
nixnax 0:2cf4880c312a 184
nixnax 50:ad4e7c3c88e5 185 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 186 {
nixnax 38:ab582987926e 187 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 188 if(start==end) {
nixnax 29:30de79d658f6 189 return;
nixnax 29:30de79d658f6 190 }
nixnax 9:0992486d4a30 191 crcReset();
nixnax 9:0992486d4a30 192 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 193 ppp.pkt.len=0;
nixnax 9:0992486d4a30 194 int unstuff=0;
nixnax 17:4918c893d802 195 int idx = start;
nixnax 17:4918c893d802 196 while(1) {
nixnax 9:0992486d4a30 197 if (unstuff==0) {
nixnax 72:ad3d12753acf 198 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 199 else {
nixnax 72:ad3d12753acf 200 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 201 ppp.pkt.len++;
nixnax 29:30de79d658f6 202 dest++;
nixnax 72:ad3d12753acf 203 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 204 }
nixnax 66:f005b9fdf4d1 205 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 206 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 207 ppp.pkt.len++;
nixnax 29:30de79d658f6 208 dest++;
nixnax 72:ad3d12753acf 209 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 210 unstuff=0;
nixnax 9:0992486d4a30 211 }
nixnax 81:9ede60e9a2c8 212 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 213 if (idx == end) break;
nixnax 9:0992486d4a30 214 }
nixnax 29:30de79d658f6 215 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 216 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 217 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 218 determinePacketType();
nixnax 29:30de79d658f6 219 } else if (v0) {
nixnax 66:f005b9fdf4d1 220 debug("PPP 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 9:0992486d4a30 221 }
nixnax 9:0992486d4a30 222 }
nixnax 9:0992486d4a30 223
nixnax 38:ab582987926e 224 // Note - the hex output of dumpFrame() can be imported into WireShark
nixnax 38:ab582987926e 225 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 38:ab582987926e 226 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 29:30de79d658f6 227 void dumpFrame()
nixnax 29:30de79d658f6 228 {
nixnax 42:4de44be70bfd 229 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 42:4de44be70bfd 230 debug(" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len);
nixnax 16:cb0b80c24ba2 231 }
nixnax 16:cb0b80c24ba2 232
nixnax 29:30de79d658f6 233 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 234 {
nixnax 29:30de79d658f6 235 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 236 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 237 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 238 } else {
nixnax 29:30de79d658f6 239 pc.putc(ch);
nixnax 29:30de79d658f6 240 }
nixnax 11:f58998c24f0b 241 }
nixnax 9:0992486d4a30 242
nixnax 66:f005b9fdf4d1 243 void sendFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 244 {
nixnax 17:4918c893d802 245 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 246 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 247 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 248 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 29:30de79d658f6 249 for(int i=0; i<ppp.pkt.len; i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 250 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 251 }
nixnax 9:0992486d4a30 252
nixnax 66:f005b9fdf4d1 253 void ipConfigRequestHandler()
nixnax 29:30de79d658f6 254 {
nixnax 64:677b9713a120 255 debug("IPCP Conf ");
nixnax 9:0992486d4a30 256 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 66:f005b9fdf4d1 257 debug("Rej\n"); // reject any options that are requested
nixnax 9:0992486d4a30 258 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 259 sendFrame();
nixnax 9:0992486d4a30 260 } else {
nixnax 64:677b9713a120 261 debug("Ack\n");
nixnax 9:0992486d4a30 262 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 263 sendFrame(); // acknowledge
nixnax 64:677b9713a120 264 debug("IPCP Ask\n");
nixnax 9:0992486d4a30 265 // send our own request now
nixnax 12:db0dc91f0231 266 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 267 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 268 sendFrame(); // this is our request
nixnax 9:0992486d4a30 269 }
nixnax 9:0992486d4a30 270 }
nixnax 9:0992486d4a30 271
nixnax 29:30de79d658f6 272 void ipAckHandler()
nixnax 29:30de79d658f6 273 {
nixnax 64:677b9713a120 274 debug("IPCP Grant\n");
nixnax 29:30de79d658f6 275 }
nixnax 9:0992486d4a30 276
nixnax 29:30de79d658f6 277 void ipNackHandler()
nixnax 29:30de79d658f6 278 {
nixnax 64:677b9713a120 279 debug("IPCP Nack\n");
nixnax 29:30de79d658f6 280 }
nixnax 9:0992486d4a30 281
nixnax 29:30de79d658f6 282 void ipDefaultHandler()
nixnax 29:30de79d658f6 283 {
nixnax 64:677b9713a120 284 debug("IPCP Other\n");
nixnax 29:30de79d658f6 285 }
nixnax 29:30de79d658f6 286
nixnax 29:30de79d658f6 287 void IPCPframe()
nixnax 29:30de79d658f6 288 {
nixnax 9:0992486d4a30 289 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 290 switch (code) {
nixnax 29:30de79d658f6 291 case 1:
nixnax 66:f005b9fdf4d1 292 ipConfigRequestHandler();
nixnax 29:30de79d658f6 293 break;
nixnax 29:30de79d658f6 294 case 2:
nixnax 29:30de79d658f6 295 ipAckHandler();
nixnax 29:30de79d658f6 296 break;
nixnax 29:30de79d658f6 297 case 3:
nixnax 29:30de79d658f6 298 ipNackHandler();
nixnax 29:30de79d658f6 299 break;
nixnax 29:30de79d658f6 300 default:
nixnax 29:30de79d658f6 301 ipDefaultHandler();
nixnax 9:0992486d4a30 302 }
nixnax 29:30de79d658f6 303 }
nixnax 9:0992486d4a30 304
nixnax 29:30de79d658f6 305 void UDPpacket()
nixnax 29:30de79d658f6 306 {
nixnax 12:db0dc91f0231 307 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 308 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 309 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 310 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 311 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 312 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 313 #endif
nixnax 12:db0dc91f0231 314 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 315 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 316 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 317 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 318 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 319 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 320 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 321 #endif
nixnax 29:30de79d658f6 322 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 323 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 324 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 325 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 81:9ede60e9a2c8 326 if(v0) debug("Len %d ", udpLength);
nixnax 29:30de79d658f6 327 int printSize = udpLength;
nixnax 29:30de79d658f6 328 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 329 if (v1) {
nixnax 29:30de79d658f6 330 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 331 char ch = udpInf[i];
nixnax 29:30de79d658f6 332 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 333 debug("%c", ch);
nixnax 29:30de79d658f6 334 } else {
nixnax 64:677b9713a120 335 debug("_");
nixnax 29:30de79d658f6 336 }
nixnax 29:30de79d658f6 337 }
nixnax 64:677b9713a120 338 debug("\n");
nixnax 29:30de79d658f6 339 }
nixnax 12:db0dc91f0231 340 }
nixnax 11:f58998c24f0b 341
nixnax 76:00e208cceb8b 342 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 343 {
nixnax 77:abf92baebb42 344
nixnax 75:0d513869231f 345 unsigned int sum=0;
nixnax 76:00e208cceb8b 346 unsigned char placeHolder;
nixnax 29:30de79d658f6 347 if (len&1) {
nixnax 76:00e208cceb8b 348 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 349 ptr[len]=0;
nixnax 29:30de79d658f6 350 }
nixnax 29:30de79d658f6 351 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 352 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 353 ptr++;
nixnax 76:00e208cceb8b 354 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 355 ptr++;
nixnax 76:00e208cceb8b 356 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 357 sum = sum + val;
nixnax 11:f58998c24f0b 358 }
nixnax 29:30de79d658f6 359 if (len&1) {
nixnax 76:00e208cceb8b 360 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 361 }
nixnax 76:00e208cceb8b 362 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 363 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 364 return ~sum;
nixnax 29:30de79d658f6 365 }
nixnax 11:f58998c24f0b 366
nixnax 29:30de79d658f6 367 void headerCheckSum()
nixnax 29:30de79d658f6 368 {
nixnax 11:f58998c24f0b 369 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 370 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 371 int sum=0;
nixnax 11:f58998c24f0b 372
nixnax 29:30de79d658f6 373 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 374 int hi = *ptr;
nixnax 29:30de79d658f6 375 ptr++;
nixnax 29:30de79d658f6 376 int lo = *ptr;
nixnax 29:30de79d658f6 377 ptr++;
nixnax 11:f58998c24f0b 378 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 379 sum = sum + val;
nixnax 11:f58998c24f0b 380 }
nixnax 11:f58998c24f0b 381 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 382 sum = ~sum;
nixnax 11:f58998c24f0b 383 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 384 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 385 }
nixnax 9:0992486d4a30 386
nixnax 29:30de79d658f6 387 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 388 {
nixnax 12:db0dc91f0231 389 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 390 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 391 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 392 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 393 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 394 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 395 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 396 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 397 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 398 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 399 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 400 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 401 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 402 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 403 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 404 #endif
nixnax 81:9ede60e9a2c8 405 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 406 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 407 char src[4];
nixnax 29:30de79d658f6 408 char dst[4];
nixnax 12:db0dc91f0231 409 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 410 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 411 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 412 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 413 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 414 chkSum[0]=0;
nixnax 29:30de79d658f6 415 chkSum[1]=0;
nixnax 12:db0dc91f0231 416 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 417 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 418 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 419 icmpSum[0]=0;
nixnax 29:30de79d658f6 420 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 421 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 422 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 423 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 424 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 425
nixnax 16:cb0b80c24ba2 426 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 427 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 428 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 429 if (v0) {
nixnax 29:30de79d658f6 430 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 431 char ch = icmpData[i];
nixnax 29:30de79d658f6 432 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 433 debug("%c",ch);
nixnax 29:30de79d658f6 434 } else {
nixnax 64:677b9713a120 435 debug("_");
nixnax 29:30de79d658f6 436 }
nixnax 29:30de79d658f6 437 }
nixnax 64:677b9713a120 438 debug("\n");
nixnax 29:30de79d658f6 439 }
nixnax 15:b0154c910143 440 sendFrame(); // reply to the ping
nixnax 29:30de79d658f6 441
nixnax 12:db0dc91f0231 442 } else {
nixnax 29:30de79d658f6 443 if (v0) {
nixnax 42:4de44be70bfd 444 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 445 }
nixnax 11:f58998c24f0b 446 }
nixnax 11:f58998c24f0b 447 }
nixnax 11:f58998c24f0b 448
nixnax 29:30de79d658f6 449 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 450 {
nixnax 29:30de79d658f6 451 if (v0) {
nixnax 42:4de44be70bfd 452 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 453 }
nixnax 29:30de79d658f6 454 }
nixnax 11:f58998c24f0b 455
nixnax 29:30de79d658f6 456 void dumpHeaderIP ()
nixnax 29:30de79d658f6 457 {
nixnax 26:11f4eb2663a7 458 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 459 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 26:11f4eb2663a7 460 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 461 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 462 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 463 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 464 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 465 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 466 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 467 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 468 char * protocol = ipPkt+9; // 1 byte
nixnax 77:abf92baebb42 469 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 470 #endif
nixnax 26:11f4eb2663a7 471 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 472 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 473
nixnax 55:43faae812be3 474 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 29:30de79d658f6 475 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 476 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 477 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 478 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 479 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 480 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 481 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 482 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 483 int protocolIP = protocol[0];
nixnax 76:00e208cceb8b 484 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 485 #endif
nixnax 55:43faae812be3 486
nixnax 29:30de79d658f6 487 char srcIP [16];
nixnax 29:30de79d658f6 488 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 29:30de79d658f6 489 char dstIP [16];
nixnax 29:30de79d658f6 490 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 42:4de44be70bfd 491 if (v0) debug("IP %s %s v%d h%d d%d e%d L%d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 42:4de44be70bfd 492 if (v0) debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 29:30de79d658f6 493 }
nixnax 26:11f4eb2663a7 494
nixnax 29:30de79d658f6 495 void dumpHeaderTCP()
nixnax 29:30de79d658f6 496 {
nixnax 81:9ede60e9a2c8 497 if( v1 ) {
nixnax 81:9ede60e9a2c8 498
nixnax 81:9ede60e9a2c8 499 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 500 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 501 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 502 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 503 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 504 #endif
nixnax 81:9ede60e9a2c8 505 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 506 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 507 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 508 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 509 #endif
nixnax 81:9ede60e9a2c8 510 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 511
nixnax 81:9ede60e9a2c8 512 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 513 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 514 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 515
nixnax 81:9ede60e9a2c8 516 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 517 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 518 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 519 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 520 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 521 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 522 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 523 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 524 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 525 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 526 }
nixnax 29:30de79d658f6 527 }
nixnax 29:30de79d658f6 528
nixnax 68:0b74763ae67f 529 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 530 {
nixnax 67:a63e3486bcda 531 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 532 int nHeader; // byte size of HTTP header
nixnax 77:abf92baebb42 533
nixnax 67:a63e3486bcda 534 if(strncmp(dataStart, "GET / HTTP/1.1", 14) == 0 ) {
nixnax 67:a63e3486bcda 535 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: PPP-Blinky\r\n"); // http header
nixnax 67:a63e3486bcda 536 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 67:a63e3486bcda 537 int contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 67:a63e3486bcda 538 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 74:7409fbeabb2e 539 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 67:a63e3486bcda 540 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 77:abf92baebb42 541 nHeader=n; // size of HTTP header
nixnax 67:a63e3486bcda 542 // this is where we insert our web page into the buffer
nixnax 67:a63e3486bcda 543 n=n+sprintf(n+dataStart,"%s\r\n", ourWebPage);
nixnax 67:a63e3486bcda 544
nixnax 68:0b74763ae67f 545 #define CONTENTLENGTHSIZE 5
nixnax 67:a63e3486bcda 546 char contentLengthString[CONTENTLENGTHSIZE+1]; // temporary buffer to create Content-Length string
nixnax 68:0b74763ae67f 547 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 67:a63e3486bcda 548 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 549
nixnax 74:7409fbeabb2e 550 } else { // all remaining requests get 404 Not Found response and heap size
nixnax 67:a63e3486bcda 551 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: PPP-Blinky\r\n"); // http header
nixnax 67:a63e3486bcda 552 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 67:a63e3486bcda 553 int contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 67:a63e3486bcda 554 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 74:7409fbeabb2e 555 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 74:7409fbeabb2e 556 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 77:abf92baebb42 557 nHeader=n; // size of HTTP header
nixnax 67:a63e3486bcda 558
nixnax 67:a63e3486bcda 559 n=n+sprintf(n+dataStart,"<!DOCTYPE html><html><head></head>"); // html start
nixnax 74:7409fbeabb2e 560 n=n+sprintf(n+dataStart,"<body><h1>File Not Found. Stack=0x%08x</h1></body>",&nHeader);
nixnax 67:a63e3486bcda 561 n=n+sprintf(n+dataStart,"</html>\r\n"); // html end
nixnax 67:a63e3486bcda 562
nixnax 68:0b74763ae67f 563 char contentLengthString[CONTENTLENGTHSIZE+1]; // temporary buffer to create Content-Length string
nixnax 68:0b74763ae67f 564 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 68:0b74763ae67f 565 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 77:abf92baebb42 566 }
nixnax 77:abf92baebb42 567 if (v2) {
nixnax 77:abf92baebb42 568 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 569 }
nixnax 67:a63e3486bcda 570
nixnax 67:a63e3486bcda 571 return n; // total byte size of our response
nixnax 67:a63e3486bcda 572 }
nixnax 67:a63e3486bcda 573
nixnax 67:a63e3486bcda 574
nixnax 29:30de79d658f6 575 void tcpHandler()
nixnax 29:30de79d658f6 576 {
nixnax 26:11f4eb2663a7 577 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 29:30de79d658f6 578 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 579 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 580 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 581 char * pktLen = ipPkt+2; // 2 bytes
nixnax 28:1aa629be05e7 582 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 583 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 584 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 585 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 586 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 587
nixnax 29:30de79d658f6 588 ident[0] = ppp.ident>>8;
nixnax 29:30de79d658f6 589 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 29:30de79d658f6 590
nixnax 29:30de79d658f6 591 char * s = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 26:11f4eb2663a7 592 char * srctcp = s + 0; // 2 bytes
nixnax 26:11f4eb2663a7 593 char * dsttcp = s + 2; // 2 bytes
nixnax 28:1aa629be05e7 594 char * seqtcp = s + 4; // 4 bytes
nixnax 28:1aa629be05e7 595 char * acktcp = s + 8; // 4 bytes
nixnax 28:1aa629be05e7 596 char * offset = s + 12; // 4 bits
nixnax 26:11f4eb2663a7 597 char * flagbitstcp = s + 12; // 9 bits
nixnax 26:11f4eb2663a7 598 char * checksumtcp = s + 16; // 2 bytes
nixnax 26:11f4eb2663a7 599
nixnax 26:11f4eb2663a7 600 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 601 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 602 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 603
nixnax 35:e7068df4d971 604 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 29:30de79d658f6 605
nixnax 35:e7068df4d971 606 char * dataStart = ppp.pkt.buf + 4 + headerSizeIP + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 607 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 81:9ede60e9a2c8 608
nixnax 77:abf92baebb42 609 unsigned int ack = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]) + tcpDataSize;
nixnax 79:f0fc1c19a550 610 unsigned int seq = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]); // use their idea of our seq
nixnax 81:9ede60e9a2c8 611
nixnax 28:1aa629be05e7 612
nixnax 29:30de79d658f6 613 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 614 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 615 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 616 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 617 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 618
nixnax 35:e7068df4d971 619 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 620 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 38:ab582987926e 621 int fastResponse = 0; // normally you wait 200ms before sending a packet but this can make it faster
nixnax 38:ab582987926e 622
nixnax 69:23f560087c16 623 // A sparse TCP flag interpreter that implements simple TCP connections from a single source
nixnax 69:23f560087c16 624 // Clients are allowed ONE push packet, after which the link is closed with a FIN flag in the ACK packet
nixnax 69:23f560087c16 625 // This strategy allows web browsers, netcat and curl to work ok while keeping the state machine simple
nixnax 77:abf92baebb42 626
nixnax 69:23f560087c16 627 switch ( flagsTCP ) {
nixnax 69:23f560087c16 628 case TCP_FLAG_ACK:
nixnax 69:23f560087c16 629 if ( tcpDataSize != 1 ) return;
nixnax 79:f0fc1c19a550 630 ack++;
nixnax 69:23f560087c16 631 case TCP_FLAG_SYN:
nixnax 69:23f560087c16 632 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - ack it
nixnax 81:9ede60e9a2c8 633 ppp.seq = ppp.seq + 10000; // create a new sequence number (normally random)
nixnax 79:f0fc1c19a550 634 seq = ppp.seq; // create a new sequence number (normally random)
nixnax 79:f0fc1c19a550 635 ack++; // for SYN flag we have to increase their sequence by 1
nixnax 69:23f560087c16 636 break;
nixnax 77:abf92baebb42 637 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 69:23f560087c16 638 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // for every push we answer once AND close the link
nixnax 69:23f560087c16 639 fastResponse = 1; // we can respond fast to a push
nixnax 69:23f560087c16 640 if ( strncmp(dataStart, "GET ", 4) == 0) { // do we see an http GET command
nixnax 69:23f560087c16 641 dataLen = httpResponse(dataStart); // send an http response
nixnax 69:23f560087c16 642 while((dataLen %4 ) !=0) { // dataLen must be a multiple of four
nixnax 77:abf92baebb42 643 dataLen++; // must be a multiple of four
nixnax 77:abf92baebb42 644 dataStart[dataLen-1]=0; // clear the byte in the buffer
nixnax 80:753f5dd2e84e 645 ack++;
nixnax 69:23f560087c16 646 }
nixnax 69:23f560087c16 647 }
nixnax 69:23f560087c16 648 break;
nixnax 77:abf92baebb42 649 case TCP_FLAG_FIN:
nixnax 69:23f560087c16 650 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 69:23f560087c16 651 case TCP_FLAG_FIN | TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 77:abf92baebb42 652 ack++; // for FIN flag we have to increase sequence by 1
nixnax 69:23f560087c16 653 break;
nixnax 77:abf92baebb42 654 default:
nixnax 69:23f560087c16 655 return; // ignore remaining packets
nixnax 28:1aa629be05e7 656 }
nixnax 81:9ede60e9a2c8 657
nixnax 77:abf92baebb42 658
nixnax 69:23f560087c16 659 // The TCP flag handling is now done
nixnax 38:ab582987926e 660 // Now we have to recalculate all the header sizes, swap IP address/port source and destination, and do the IP and TCP checksums
nixnax 26:11f4eb2663a7 661
nixnax 65:23b17c43aa0f 662 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 663 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 664 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 665 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 666
nixnax 60:2b770949c911 667 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 668 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 669 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 29:30de79d658f6 670
nixnax 38:ab582987926e 671 acktcp[0]=ack>>24;
nixnax 38:ab582987926e 672 acktcp[1]=ack>>16;
nixnax 38:ab582987926e 673 acktcp[2]=ack>>8;
nixnax 67:a63e3486bcda 674 acktcp[3]=ack>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 675
nixnax 38:ab582987926e 676 seqtcp[0]=seq>>24;
nixnax 38:ab582987926e 677 seqtcp[1]=seq>>16;
nixnax 38:ab582987926e 678 seqtcp[2]=seq>>8;
nixnax 67:a63e3486bcda 679 seqtcp[3]=seq>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 680
nixnax 38:ab582987926e 681 flagbitstcp[1] = flagsOut; // set up the new flags
nixnax 38:ab582987926e 682
nixnax 38:ab582987926e 683 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 684 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 685 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 686 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 687 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 688
nixnax 38:ab582987926e 689 // the header is all set up, now do the IP and TCP checksums
nixnax 36:2a9b457f8276 690
nixnax 61:b3c1a04efd0a 691 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 692 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 693 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 694
nixnax 64:677b9713a120 695 // 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 696 // 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 697
nixnax 62:f192926e42f1 698 char * pseudoHeader = s-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 699 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 700 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 701 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 702 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 703 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 704 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 705
nixnax 61:b3c1a04efd0a 706 // pseudo-header built, now we can calculate TCP checksum
nixnax 63:9253b0e1b7d8 707
nixnax 29:30de79d658f6 708 checksumtcp[0]=0;
nixnax 29:30de79d658f6 709 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 710 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 711 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 712 checksumtcp[1]=pseudoHeaderSum;
nixnax 61:b3c1a04efd0a 713 memcpy( s-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 60:2b770949c911 714
nixnax 36:2a9b457f8276 715 if (fastResponse==1) {
nixnax 36:2a9b457f8276 716 fastResponse=0; // reset and skip 200 ms wait
nixnax 36:2a9b457f8276 717 } else {
nixnax 81:9ede60e9a2c8 718 // normally, you wait 200 ms before responding to a TCP packet
nixnax 68:0b74763ae67f 719 // remove the wait to respond faster
nixnax 78:809c2631a5eb 720 // wait(0.2);
nixnax 36:2a9b457f8276 721 }
nixnax 81:9ede60e9a2c8 722 dumpHeaderTCP();
nixnax 81:9ede60e9a2c8 723 sendFrame(); // All preparation complete - send the TCP response
nixnax 29:30de79d658f6 724 }
nixnax 26:11f4eb2663a7 725
nixnax 29:30de79d658f6 726 void dumpDataTCP()
nixnax 29:30de79d658f6 727 {
nixnax 26:11f4eb2663a7 728 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 729 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 730 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 731 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 732 if (v1) {
nixnax 42:4de44be70bfd 733 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 734 }
nixnax 29:30de79d658f6 735 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 736 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 737 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 738 }
nixnax 29:30de79d658f6 739 }
nixnax 26:11f4eb2663a7 740
nixnax 29:30de79d658f6 741 void TCPpacket()
nixnax 29:30de79d658f6 742 {
nixnax 26:11f4eb2663a7 743 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 744 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 26:11f4eb2663a7 745 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 746 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 747 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 748 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 749 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 750 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 751 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 752 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 753 char * protocol = ipPkt+9; // 1 byte
nixnax 29:30de79d658f6 754 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 755 #endif
nixnax 26:11f4eb2663a7 756 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 757 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 758
nixnax 55:43faae812be3 759 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 29:30de79d658f6 760 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 761 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 762 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 763 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 764 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 765 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 766 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 767 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 768 int protocolIP = protocol[0];
nixnax 26:11f4eb2663a7 769 int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 63:9253b0e1b7d8 770 #endif
nixnax 29:30de79d658f6 771 char srcIP [16];
nixnax 29:30de79d658f6 772 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 29:30de79d658f6 773 char dstIP [16];
nixnax 29:30de79d658f6 774 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 29:30de79d658f6 775 if (v0) {
nixnax 42:4de44be70bfd 776 debug("IP %s %s v%d h%d d%d e%d L%d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 29:30de79d658f6 777 }
nixnax 29:30de79d658f6 778 if (v0) {
nixnax 42:4de44be70bfd 779 debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 29:30de79d658f6 780 }
nixnax 81:9ede60e9a2c8 781 dumpHeaderTCP();
nixnax 77:abf92baebb42 782 if (v2) {
nixnax 77:abf92baebb42 783 dumpDataTCP();
nixnax 77:abf92baebb42 784 }
nixnax 26:11f4eb2663a7 785 tcpHandler();
nixnax 11:f58998c24f0b 786 }
nixnax 11:f58998c24f0b 787
nixnax 29:30de79d658f6 788 void otherProtocol()
nixnax 29:30de79d658f6 789 {
nixnax 64:677b9713a120 790 debug("Other IP protocol");
nixnax 29:30de79d658f6 791 }
nixnax 26:11f4eb2663a7 792
nixnax 29:30de79d658f6 793 void IPframe()
nixnax 29:30de79d658f6 794 {
nixnax 10:74f8233f72c0 795 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 796 switch (protocol) {
nixnax 29:30de79d658f6 797 case 1:
nixnax 29:30de79d658f6 798 ICMPpacket();
nixnax 29:30de79d658f6 799 break;
nixnax 29:30de79d658f6 800 case 2:
nixnax 29:30de79d658f6 801 IGMPpacket();
nixnax 29:30de79d658f6 802 break;
nixnax 29:30de79d658f6 803 case 17:
nixnax 29:30de79d658f6 804 UDPpacket();
nixnax 29:30de79d658f6 805 break;
nixnax 29:30de79d658f6 806 case 6:
nixnax 29:30de79d658f6 807 TCPpacket();
nixnax 29:30de79d658f6 808 break;
nixnax 29:30de79d658f6 809 default:
nixnax 29:30de79d658f6 810 otherProtocol();
nixnax 29:30de79d658f6 811 }
nixnax 29:30de79d658f6 812 }
nixnax 9:0992486d4a30 813
nixnax 29:30de79d658f6 814 void LCPconfReq()
nixnax 29:30de79d658f6 815 {
nixnax 64:677b9713a120 816 debug("LCP Config ");
nixnax 9:0992486d4a30 817 if (ppp.pkt.buf[7] != 4) {
nixnax 11:f58998c24f0b 818 ppp.pkt.buf[4]=4; // allow only no options
nixnax 64:677b9713a120 819 debug("Reject\n");
nixnax 29:30de79d658f6 820 sendFrame();
nixnax 9:0992486d4a30 821 } else {
nixnax 9:0992486d4a30 822 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 823 debug("Ack\n");
nixnax 9:0992486d4a30 824 sendFrame();
nixnax 64:677b9713a120 825 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 826 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 827 sendFrame();
nixnax 9:0992486d4a30 828 }
nixnax 9:0992486d4a30 829 }
nixnax 9:0992486d4a30 830
nixnax 29:30de79d658f6 831 void LCPconfAck()
nixnax 29:30de79d658f6 832 {
nixnax 64:677b9713a120 833 debug("LCP Ack\n");
nixnax 29:30de79d658f6 834 }
nixnax 9:0992486d4a30 835
nixnax 29:30de79d658f6 836 void LCPend()
nixnax 29:30de79d658f6 837 {
nixnax 29:30de79d658f6 838 ppp.pkt.buf[4]=6;
nixnax 29:30de79d658f6 839 sendFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 840 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 841 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 842 debug("LCP End\n");
nixnax 9:0992486d4a30 843 }
nixnax 9:0992486d4a30 844
nixnax 29:30de79d658f6 845 void LCPother()
nixnax 29:30de79d658f6 846 {
nixnax 64:677b9713a120 847 debug("LCP Other\n");
nixnax 29:30de79d658f6 848 dumpFrame();
nixnax 29:30de79d658f6 849 }
nixnax 29:30de79d658f6 850
nixnax 29:30de79d658f6 851 void LCPframe()
nixnax 29:30de79d658f6 852 {
nixnax 29:30de79d658f6 853 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 854 switch (code) {
nixnax 29:30de79d658f6 855 case 1:
nixnax 29:30de79d658f6 856 LCPconfReq();
nixnax 29:30de79d658f6 857 break; // config request
nixnax 29:30de79d658f6 858 case 2:
nixnax 29:30de79d658f6 859 LCPconfAck();
nixnax 29:30de79d658f6 860 break; // config ack
nixnax 29:30de79d658f6 861 case 5:
nixnax 29:30de79d658f6 862 LCPend();
nixnax 29:30de79d658f6 863 break; // end connection
nixnax 29:30de79d658f6 864 default:
nixnax 29:30de79d658f6 865 LCPother();
nixnax 29:30de79d658f6 866 }
nixnax 9:0992486d4a30 867 }
nixnax 9:0992486d4a30 868
nixnax 29:30de79d658f6 869 void discardedFrame()
nixnax 29:30de79d658f6 870 {
nixnax 29:30de79d658f6 871 if (v0) {
nixnax 71:965619fedb3a 872 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 873 }
nixnax 9:0992486d4a30 874 }
nixnax 9:0992486d4a30 875
nixnax 29:30de79d658f6 876 void determinePacketType()
nixnax 29:30de79d658f6 877 {
nixnax 29:30de79d658f6 878 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 879 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 880 return;
nixnax 29:30de79d658f6 881 }
nixnax 29:30de79d658f6 882 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 883 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 884 return;
nixnax 29:30de79d658f6 885 }
nixnax 29:30de79d658f6 886 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 887 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 888 return;
nixnax 29:30de79d658f6 889 }
nixnax 9:0992486d4a30 890 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 891 switch (packetType) {
nixnax 29:30de79d658f6 892 case 0xc0:
nixnax 29:30de79d658f6 893 LCPframe();
nixnax 29:30de79d658f6 894 break; // link control
nixnax 29:30de79d658f6 895 case 0x80:
nixnax 29:30de79d658f6 896 IPCPframe();
nixnax 29:30de79d658f6 897 break; // IP control
nixnax 29:30de79d658f6 898 case 0x00:
nixnax 29:30de79d658f6 899 IPframe();
nixnax 29:30de79d658f6 900 break; // IP itself
nixnax 29:30de79d658f6 901 default:
nixnax 29:30de79d658f6 902 discardedFrame();
nixnax 9:0992486d4a30 903 }
nixnax 29:30de79d658f6 904 }
nixnax 9:0992486d4a30 905
nixnax 50:ad4e7c3c88e5 906 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 907 {
nixnax 81:9ede60e9a2c8 908 while(1)
nixnax 81:9ede60e9a2c8 909 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 910 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 911 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 912 if (rx==FRAME_7E) {
nixnax 81:9ede60e9a2c8 913 if (ppp.hdlc.frameFound == 0) { // we are still waiting for a frame start
nixnax 81:9ede60e9a2c8 914 ppp.hdlc.frameFound = 1; // we found our first frame start
nixnax 81:9ede60e9a2c8 915 ppp.hdlc.frameStartIndex=ppp.rx.tail; // remember where the frame character is in the buffer
nixnax 51:a86d56844324 916 } else {
nixnax 81:9ede60e9a2c8 917 // we have previously found a frame start
nixnax 81:9ede60e9a2c8 918 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 81:9ede60e9a2c8 919 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 81:9ede60e9a2c8 920 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 81:9ede60e9a2c8 921 break;
nixnax 50:ad4e7c3c88e5 922 }
nixnax 50:ad4e7c3c88e5 923 }
nixnax 50:ad4e7c3c88e5 924 }
nixnax 50:ad4e7c3c88e5 925 }
nixnax 50:ad4e7c3c88e5 926
nixnax 29:30de79d658f6 927 void scanForConnectString()
nixnax 29:30de79d658f6 928 {
nixnax 81:9ede60e9a2c8 929 while(ppp.online == 0) {
nixnax 81:9ede60e9a2c8 930 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 81:9ede60e9a2c8 931 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENTCLIENT" );
nixnax 81:9ede60e9a2c8 932 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 933 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 934 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 935 if (found1 != NULL) {
nixnax 81:9ede60e9a2c8 936 //strcpy( found1, "FOUND!FOUND!" ); // overwrite so we don't find it again
nixnax 81:9ede60e9a2c8 937 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 81:9ede60e9a2c8 938 memset(ppp.rx.buf, 0, RXBUFLEN); // clear the receive buffer
nixnax 81:9ede60e9a2c8 939 pc.puts("CLIENTSERVER");
nixnax 81:9ede60e9a2c8 940 if (v0) debug("Found connect string \"CLIENTCLIENT\"\n");
nixnax 81:9ede60e9a2c8 941 }
nixnax 81:9ede60e9a2c8 942 if (found2 != NULL) {
nixnax 81:9ede60e9a2c8 943 if (v0) debug("Found HDLC frame start (7E)\n");
nixnax 81:9ede60e9a2c8 944 }
nixnax 71:965619fedb3a 945 ppp.online=1; // we are connected, so stop looking for the string
nixnax 9:0992486d4a30 946 }
nixnax 9:0992486d4a30 947 }
nixnax 81:9ede60e9a2c8 948
nixnax 9:0992486d4a30 949 }
nixnax 9:0992486d4a30 950
nixnax 0:2cf4880c312a 951 int main()
nixnax 0:2cf4880c312a 952 {
nixnax 14:c65831c25aaa 953 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 954 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 955 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 956 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 957 #endif
nixnax 9:0992486d4a30 958 pppInitStruct(); // initialize all the PPP properties
nixnax 81:9ede60e9a2c8 959 ppp.seq=1000; // initial TCP sequence number
nixnax 81:9ede60e9a2c8 960
nixnax 9:0992486d4a30 961 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 0:2cf4880c312a 962 while(1) {
nixnax 81:9ede60e9a2c8 963 debug("scan\n");
nixnax 51:a86d56844324 964 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 965 debug("found\n");
nixnax 81:9ede60e9a2c8 966 while(ppp.online) {
nixnax 81:9ede60e9a2c8 967 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 968 }
nixnax 7:ab147f5e97ac 969 }
nixnax 7:ab147f5e97ac 970 }