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@106:d14e6b597ca3, 2017-08-03 (annotated)

Committer:
nixnax
Date:
Thu Aug 03 11:14:28 2017 +0000
Revision:
106:d14e6b597ca3
Parent:
105:45001195b325
Child:
107:5fe806713d49
Shortened Connect string. IPCP uses suggested IP. Removed framefound.

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 0:2cf4880c312a 10
nixnax 41:e58a5a09f411 11 // Handy reading material
nixnax 6:fba4c2e817b8 12 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 9:0992486d4a30 13 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 39:b90183d35f1e 14 // http://bit.ly/dialup777error - how to solve Dial Up Error 777 in Windows 7/8/10
nixnax 41:e58a5a09f411 15 // http://atari.kensclassics.org/wcomlog.htm
nixnax 6:fba4c2e817b8 16
nixnax 29:30de79d658f6 17 // Handy tools
nixnax 44:d0c61ae49ea5 18 // https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax 92:cb962b365cce 19 // https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets -
nixnax 29:30de79d658f6 20 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 95:40af49390daf 21 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax 29:30de79d658f6 22 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 41:e58a5a09f411 23 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 91:5141ae9fba53 24 // Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax 41:e58a5a09f411 25
nixnax 92:cb962b365cce 26 // Connecting PPP-Blinky to Linux
nixnax 93:9675adc36882 27 // PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax 93:9675adc36882 28 // pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax 92:cb962b365cce 29 // in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax 93:9675adc36882 30 // See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax 93:9675adc36882 31
nixnax 93:9675adc36882 32 // Ok, enough talking, time to check out some code!!
nixnax 106:d14e6b597ca3 33
nixnax 81:9ede60e9a2c8 34 #include "mbed.h"
nixnax 66:f005b9fdf4d1 35
nixnax 93:9675adc36882 36 // The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 37 // 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 94:8ee3eec2a2bb 38 #define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax 0:2cf4880c312a 39
nixnax 41:e58a5a09f411 40 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 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 88:b4a71242837c 44 #if defined(TARGET_LPC1768)
nixnax 85:53e57ff1cf05 45 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 88:b4a71242837c 46 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE)
nixnax 85:53e57ff1cf05 47 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 85:53e57ff1cf05 48 #else
nixnax 85:53e57ff1cf05 49 #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 50 #endif
nixnax 85:53e57ff1cf05 51
nixnax 93:9675adc36882 52 #define debug(x...) xx.printf (x)
nixnax 85:53e57ff1cf05 53
nixnax 41:e58a5a09f411 54 #else
nixnax 42:4de44be70bfd 55 #define debug(x...) {}
nixnax 41:e58a5a09f411 56 #endif
nixnax 41:e58a5a09f411 57
nixnax 93:9675adc36882 58 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 90:55e0f243a7ce 59 #define v0 0
nixnax 93:9675adc36882 60 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 61 #define v1 0
nixnax 93:9675adc36882 62 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 77:abf92baebb42 63 #define v2 0
nixnax 29:30de79d658f6 64
nixnax 93:9675adc36882 65 // this is the webpage we serve when we get an HTTP request to root (/)
nixnax 93:9675adc36882 66 // keep size under ~900 bytes to fit into a single PPP packet
nixnax 93:9675adc36882 67 const static char rootWebPage[] = "\
nixnax 66:f005b9fdf4d1 68 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 69 <html>\
nixnax 66:f005b9fdf4d1 70 <head>\
nixnax 66:f005b9fdf4d1 71 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 72 <script>\
nixnax 66:f005b9fdf4d1 73 window.onload=function(){\
nixnax 66:f005b9fdf4d1 74 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 75 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 76 </script>\
nixnax 66:f005b9fdf4d1 77 </head>\
nixnax 66:f005b9fdf4d1 78 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 79 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 80 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 81 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 82 </body>\
nixnax 69:23f560087c16 83 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 84
nixnax 73:2f56ec87dbe9 85 // 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 86 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 87 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 88 // See instructions at the top.
nixnax 73:2f56ec87dbe9 89 // 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 90 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 91
nixnax 29:30de79d658f6 92 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 93
nixnax 66:f005b9fdf4d1 94 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 95 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 96
nixnax 29:30de79d658f6 97 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 98 struct pppType {
nixnax 38:ab582987926e 99 int online; // we hunt for a PPP connection if this is zero
nixnax 87:9f5ac1fabd95 100 unsigned int ident; // our IP ident value
nixnax 38:ab582987926e 101 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 102 int ledState; // state of LED1
nixnax 98:3babad0d1bd4 103 int httpPageCount;
nixnax 4:a469050d5b80 104 struct {
nixnax 105:45001195b325 105 #define RXBUFLEN (1<<11)
nixnax 93:9675adc36882 106 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 8192 bytes)
nixnax 85:53e57ff1cf05 107 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 93:9675adc36882 108 int head;
nixnax 93:9675adc36882 109 int tail;
nixnax 95:40af49390daf 110 int rtail;
nixnax 93:9675adc36882 111 int buflevel;
nixnax 38:ab582987926e 112 } rx; // serial port objects
nixnax 4:a469050d5b80 113 struct {
nixnax 38:ab582987926e 114 int len; // number of bytes in buffer
nixnax 38:ab582987926e 115 int crc; // PPP CRC (frame check)
nixnax 77:abf92baebb42 116 #define TCP_max_size 3300
nixnax 77:abf92baebb42 117 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 118 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 119 struct {
nixnax 50:ad4e7c3c88e5 120 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 121 int frameEndIndex; // frame end marker
nixnax 50:ad4e7c3c88e5 122 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 123 };
nixnax 31:e000c1b9c565 124
nixnax 29:30de79d658f6 125 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 126
nixnax 93:9675adc36882 127 // Initialize our global structure, clear the buffer, etc.
nixnax 29:30de79d658f6 128 void pppInitStruct()
nixnax 29:30de79d658f6 129 {
nixnax 81:9ede60e9a2c8 130 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 131 ppp.online=0;
nixnax 29:30de79d658f6 132 ppp.rx.tail=0;
nixnax 93:9675adc36882 133 ppp.rx.rtail=0;
nixnax 29:30de79d658f6 134 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 135 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 136 ppp.pkt.len=0;
nixnax 83:cdcb81d1910f 137 ppp.ident=1000;
nixnax 29:30de79d658f6 138 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 139 ppp.hdlc.frameStartIndex=0;
nixnax 98:3babad0d1bd4 140 ppp.httpPageCount=0;
nixnax 29:30de79d658f6 141 }
nixnax 26:11f4eb2663a7 142
nixnax 43:aa57db08995d 143 void led1Toggle()
nixnax 43:aa57db08995d 144 {
nixnax 43:aa57db08995d 145 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 93:9675adc36882 146 led1 = ppp.ledState; // toggle led
nixnax 43:aa57db08995d 147 }
nixnax 43:aa57db08995d 148
nixnax 29:30de79d658f6 149 void crcReset()
nixnax 29:30de79d658f6 150 {
nixnax 29:30de79d658f6 151 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 152 }
nixnax 4:a469050d5b80 153
nixnax 29:30de79d658f6 154 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 155 {
nixnax 29:30de79d658f6 156 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 157 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 158 x>>=1;
nixnax 29:30de79d658f6 159 }
nixnax 29:30de79d658f6 160 }
nixnax 29:30de79d658f6 161
nixnax 29:30de79d658f6 162 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 163 {
nixnax 31:e000c1b9c565 164 crcReset();
nixnax 31:e000c1b9c565 165 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 166 return ppp.crc;
nixnax 29:30de79d658f6 167 }
nixnax 0:2cf4880c312a 168
nixnax 85:53e57ff1cf05 169 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 170 void fillbuf()
nixnax 0:2cf4880c312a 171 {
nixnax 85:53e57ff1cf05 172 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 173 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 93:9675adc36882 174 if ( hd == ppp.rx.rtail ) {
nixnax 85:53e57ff1cf05 175 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 176 return;
nixnax 83:cdcb81d1910f 177 }
nixnax 17:4918c893d802 178 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 179 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 180 ppp.rx.buflevel++;
nixnax 15:b0154c910143 181 }
nixnax 0:2cf4880c312a 182 }
nixnax 0:2cf4880c312a 183
nixnax 85:53e57ff1cf05 184 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 185 {
nixnax 43:aa57db08995d 186 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 187 return emptyStatus;
nixnax 0:2cf4880c312a 188 }
nixnax 0:2cf4880c312a 189
nixnax 85:53e57ff1cf05 190 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 191 {
nixnax 63:9253b0e1b7d8 192 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 193 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 194 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 195 return x;
nixnax 0:2cf4880c312a 196 }
nixnax 0:2cf4880c312a 197
nixnax 95:40af49390daf 198 // Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 95:40af49390daf 199 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 95:40af49390daf 200 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 95:40af49390daf 201 void dumpPPPFrame()
nixnax 95:40af49390daf 202 {
nixnax 95:40af49390daf 203 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 95:40af49390daf 204 debug(" CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 95:40af49390daf 205 }
nixnax 95:40af49390daf 206
nixnax 50:ad4e7c3c88e5 207 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 208 {
nixnax 38:ab582987926e 209 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 210 if(start==end) {
nixnax 29:30de79d658f6 211 return;
nixnax 29:30de79d658f6 212 }
nixnax 9:0992486d4a30 213 crcReset();
nixnax 9:0992486d4a30 214 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 215 ppp.pkt.len=0;
nixnax 9:0992486d4a30 216 int unstuff=0;
nixnax 17:4918c893d802 217 int idx = start;
nixnax 17:4918c893d802 218 while(1) {
nixnax 9:0992486d4a30 219 if (unstuff==0) {
nixnax 72:ad3d12753acf 220 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 221 else {
nixnax 72:ad3d12753acf 222 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 223 ppp.pkt.len++;
nixnax 29:30de79d658f6 224 dest++;
nixnax 72:ad3d12753acf 225 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 226 }
nixnax 66:f005b9fdf4d1 227 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 228 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 229 ppp.pkt.len++;
nixnax 29:30de79d658f6 230 dest++;
nixnax 72:ad3d12753acf 231 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 232 unstuff=0;
nixnax 9:0992486d4a30 233 }
nixnax 81:9ede60e9a2c8 234 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 235 if (idx == end) break;
nixnax 9:0992486d4a30 236 }
nixnax 29:30de79d658f6 237 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 238 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 239 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 240 determinePacketType();
nixnax 90:55e0f243a7ce 241 } else {
nixnax 95:40af49390daf 242 if (0) { // don't normally report FCS because windows early-terminates packets, and early-terminated packets all have FCS errors.
nixnax 95:40af49390daf 243 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 244 }
nixnax 9:0992486d4a30 245 }
nixnax 9:0992486d4a30 246 }
nixnax 9:0992486d4a30 247
nixnax 29:30de79d658f6 248 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 249 {
nixnax 29:30de79d658f6 250 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 251 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 252 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 253 } else {
nixnax 29:30de79d658f6 254 pc.putc(ch);
nixnax 29:30de79d658f6 255 }
nixnax 11:f58998c24f0b 256 }
nixnax 9:0992486d4a30 257
nixnax 93:9675adc36882 258 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 259 {
nixnax 17:4918c893d802 260 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 261 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 262 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 263 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 95:40af49390daf 264 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 265 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 95:40af49390daf 266
nixnax 93:9675adc36882 267 if((i&0x7f)==0) fillbuf(); // handle received characters very every 128 sent
nixnax 93:9675adc36882 268 }
nixnax 16:cb0b80c24ba2 269 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 270 }
nixnax 9:0992486d4a30 271
nixnax 93:9675adc36882 272 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 273 {
nixnax 93:9675adc36882 274 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 275 ppp.pkt.buf[4]=2; // change code to ack
nixnax 106:d14e6b597ca3 276 send_pppFrame(); // acknowledge everything they ask for - assume it's an IP address
nixnax 106:d14e6b597ca3 277
nixnax 93:9675adc36882 278 debug("Our IPCP Ask\n");
nixnax 92:cb962b365cce 279 ppp.pkt.buf[4]=1; // change code to request
nixnax 106:d14e6b597ca3 280 ppp.pkt.buf[7]=4; // no options in this request
nixnax 106:d14e6b597ca3 281 ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax 103:4f5512dd11cf 282 send_pppFrame(); // send our request
nixnax 9:0992486d4a30 283 }
nixnax 9:0992486d4a30 284
nixnax 93:9675adc36882 285 void ipcpAckHandler()
nixnax 29:30de79d658f6 286 {
nixnax 93:9675adc36882 287 debug("Their IPCP Grant\n");
nixnax 29:30de79d658f6 288 }
nixnax 9:0992486d4a30 289
nixnax 106:d14e6b597ca3 290
nixnax 106:d14e6b597ca3 291
nixnax 106:d14e6b597ca3 292
nixnax 106:d14e6b597ca3 293
nixnax 106:d14e6b597ca3 294
nixnax 106:d14e6b597ca3 295
nixnax 93:9675adc36882 296 void ipcpNackHandler()
nixnax 29:30de79d658f6 297 {
nixnax 106:d14e6b597ca3 298 debug("Their IPCP Nack, Our ACK\n");
nixnax 106:d14e6b597ca3 299 if (ppp.pkt.buf[8]=3) { // check if the NACK contains an IP address parameter
nixnax 106:d14e6b597ca3 300 ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax 106:d14e6b597ca3 301 send_pppFrame(); // let's request this IP address as ours
nixnax 106:d14e6b597ca3 302 } // if it's not an IP nack we ignore it
nixnax 29:30de79d658f6 303 }
nixnax 9:0992486d4a30 304
nixnax 93:9675adc36882 305 void ipcpDefaultHandler()
nixnax 29:30de79d658f6 306 {
nixnax 93:9675adc36882 307 debug("Their IPCP Other\n");
nixnax 29:30de79d658f6 308 }
nixnax 29:30de79d658f6 309
nixnax 29:30de79d658f6 310 void IPCPframe()
nixnax 29:30de79d658f6 311 {
nixnax 9:0992486d4a30 312 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 313 switch (code) {
nixnax 29:30de79d658f6 314 case 1:
nixnax 93:9675adc36882 315 ipcpConfigRequestHandler();
nixnax 29:30de79d658f6 316 break;
nixnax 29:30de79d658f6 317 case 2:
nixnax 93:9675adc36882 318 ipcpAckHandler();
nixnax 29:30de79d658f6 319 break;
nixnax 29:30de79d658f6 320 case 3:
nixnax 93:9675adc36882 321 ipcpNackHandler();
nixnax 29:30de79d658f6 322 break;
nixnax 29:30de79d658f6 323 default:
nixnax 93:9675adc36882 324 ipcpDefaultHandler();
nixnax 9:0992486d4a30 325 }
nixnax 29:30de79d658f6 326 }
nixnax 9:0992486d4a30 327
nixnax 29:30de79d658f6 328 void UDPpacket()
nixnax 29:30de79d658f6 329 {
nixnax 12:db0dc91f0231 330 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 331 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 332 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 333 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 334 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 335 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 336 #endif
nixnax 12:db0dc91f0231 337 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 338 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 339 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 340 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 341 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 342 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 343 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 344 #endif
nixnax 29:30de79d658f6 345 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 346 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 347 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 348 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 349 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 350 int printSize = udpLength;
nixnax 29:30de79d658f6 351 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 352 if (v1) {
nixnax 29:30de79d658f6 353 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 354 char ch = udpInf[i];
nixnax 29:30de79d658f6 355 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 356 debug("%c", ch);
nixnax 29:30de79d658f6 357 } else {
nixnax 64:677b9713a120 358 debug("_");
nixnax 29:30de79d658f6 359 }
nixnax 29:30de79d658f6 360 }
nixnax 29:30de79d658f6 361 }
nixnax 83:cdcb81d1910f 362 if (v0) debug("\n");
nixnax 12:db0dc91f0231 363 }
nixnax 11:f58998c24f0b 364
nixnax 76:00e208cceb8b 365 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 366 {
nixnax 77:abf92baebb42 367
nixnax 75:0d513869231f 368 unsigned int sum=0;
nixnax 76:00e208cceb8b 369 unsigned char placeHolder;
nixnax 29:30de79d658f6 370 if (len&1) {
nixnax 76:00e208cceb8b 371 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 372 ptr[len]=0;
nixnax 29:30de79d658f6 373 }
nixnax 29:30de79d658f6 374 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 375 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 376 ptr++;
nixnax 76:00e208cceb8b 377 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 378 ptr++;
nixnax 76:00e208cceb8b 379 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 380 sum = sum + val;
nixnax 11:f58998c24f0b 381 }
nixnax 29:30de79d658f6 382 if (len&1) {
nixnax 76:00e208cceb8b 383 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 384 }
nixnax 76:00e208cceb8b 385 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 386 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 387 return ~sum;
nixnax 29:30de79d658f6 388 }
nixnax 11:f58998c24f0b 389
nixnax 29:30de79d658f6 390 void headerCheckSum()
nixnax 29:30de79d658f6 391 {
nixnax 11:f58998c24f0b 392 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 393 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 394 int sum=0;
nixnax 11:f58998c24f0b 395
nixnax 29:30de79d658f6 396 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 397 int hi = *ptr;
nixnax 29:30de79d658f6 398 ptr++;
nixnax 29:30de79d658f6 399 int lo = *ptr;
nixnax 29:30de79d658f6 400 ptr++;
nixnax 11:f58998c24f0b 401 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 402 sum = sum + val;
nixnax 11:f58998c24f0b 403 }
nixnax 11:f58998c24f0b 404 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 405 sum = ~sum;
nixnax 11:f58998c24f0b 406 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 407 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 408 }
nixnax 9:0992486d4a30 409
nixnax 29:30de79d658f6 410 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 411 {
nixnax 12:db0dc91f0231 412 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 413 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 414 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 415 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 416 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 417 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 418 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 419 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 420 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 421 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 422 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 423 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 424 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 425 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 426 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 427 #endif
nixnax 81:9ede60e9a2c8 428 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 429 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 430 char src[4];
nixnax 29:30de79d658f6 431 char dst[4];
nixnax 12:db0dc91f0231 432 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 433 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 434 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 435 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 436 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 437 chkSum[0]=0;
nixnax 29:30de79d658f6 438 chkSum[1]=0;
nixnax 12:db0dc91f0231 439 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 440 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 441 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 442 icmpSum[0]=0;
nixnax 29:30de79d658f6 443 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 444 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 445 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 446 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 447 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 448
nixnax 16:cb0b80c24ba2 449 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 450 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 451 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 452 if (v0) {
nixnax 29:30de79d658f6 453 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 454 char ch = icmpData[i];
nixnax 29:30de79d658f6 455 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 456 debug("%c",ch);
nixnax 29:30de79d658f6 457 } else {
nixnax 64:677b9713a120 458 debug("_");
nixnax 29:30de79d658f6 459 }
nixnax 29:30de79d658f6 460 }
nixnax 64:677b9713a120 461 debug("\n");
nixnax 29:30de79d658f6 462 }
nixnax 93:9675adc36882 463 send_pppFrame(); // reply to the ping
nixnax 29:30de79d658f6 464
nixnax 12:db0dc91f0231 465 } else {
nixnax 29:30de79d658f6 466 if (v0) {
nixnax 42:4de44be70bfd 467 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 468 }
nixnax 11:f58998c24f0b 469 }
nixnax 11:f58998c24f0b 470 }
nixnax 11:f58998c24f0b 471
nixnax 29:30de79d658f6 472 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 473 {
nixnax 29:30de79d658f6 474 if (v0) {
nixnax 42:4de44be70bfd 475 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 476 }
nixnax 29:30de79d658f6 477 }
nixnax 11:f58998c24f0b 478
nixnax 29:30de79d658f6 479 void dumpHeaderIP ()
nixnax 29:30de79d658f6 480 {
nixnax 95:40af49390daf 481 if (v0) {
nixnax 95:40af49390daf 482 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 483 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 484 char * version = ipPkt; // top 4 bits
nixnax 95:40af49390daf 485 char * ihl = ipPkt; // bottom 4 bits
nixnax 95:40af49390daf 486 char * dscp = ipPkt+1; // top 6 bits
nixnax 95:40af49390daf 487 char * ecn = ipPkt+1; // lower 2 bits
nixnax 95:40af49390daf 488 char * pktLen = ipPkt+2; // 2 bytes
nixnax 95:40af49390daf 489 char * ident = ipPkt+4; // 2 bytes
nixnax 95:40af49390daf 490 char * flags = ipPkt+6; // 2 bits
nixnax 95:40af49390daf 491 char * ttl = ipPkt+8; // 1 byte
nixnax 95:40af49390daf 492 char * protocol = ipPkt+9; // 1 byte
nixnax 95:40af49390daf 493 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 494 #endif
nixnax 95:40af49390daf 495 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 95:40af49390daf 496 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 497
nixnax 55:43faae812be3 498 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 499 int versionIP = (version[0]>>4)&0xf;
nixnax 95:40af49390daf 500 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 95:40af49390daf 501 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 95:40af49390daf 502 int ecnIP = ecn[0]&3;
nixnax 95:40af49390daf 503 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 95:40af49390daf 504 int identIP = (ident[0]<<8)|ident[1];
nixnax 95:40af49390daf 505 int flagsIP = flags[0]>>14&3;
nixnax 95:40af49390daf 506 int ttlIP = ttl[0];
nixnax 95:40af49390daf 507 int protocolIP = protocol[0];
nixnax 95:40af49390daf 508 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 509 #endif
nixnax 55:43faae812be3 510
nixnax 95:40af49390daf 511 char srcIP [16];
nixnax 95:40af49390daf 512 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 95:40af49390daf 513 char dstIP [16];
nixnax 95:40af49390daf 514 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 95:40af49390daf 515 debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 95:40af49390daf 516 debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 95:40af49390daf 517 }
nixnax 29:30de79d658f6 518 }
nixnax 26:11f4eb2663a7 519
nixnax 29:30de79d658f6 520 void dumpHeaderTCP()
nixnax 29:30de79d658f6 521 {
nixnax 83:cdcb81d1910f 522 if( v0 ) {
nixnax 81:9ede60e9a2c8 523 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 524 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 525 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 526 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 527 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 528 #endif
nixnax 81:9ede60e9a2c8 529 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 530 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 531 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 532 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 533 #endif
nixnax 81:9ede60e9a2c8 534 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 535
nixnax 81:9ede60e9a2c8 536 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 537 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 538 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 539
nixnax 81:9ede60e9a2c8 540 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 541 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 542 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 543 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 544 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 545 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 546 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 547 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 548 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 549 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 550 }
nixnax 29:30de79d658f6 551 }
nixnax 29:30de79d658f6 552
nixnax 68:0b74763ae67f 553 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 554 {
nixnax 67:a63e3486bcda 555 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 556 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 557 int contentLengthStart; // index where HTML starts
nixnax 93:9675adc36882 558 int xFetch, httpGetRoot; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 559
nixnax 98:3babad0d1bd4 560 ppp.httpPageCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 561
nixnax 98:3babad0d1bd4 562 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found GET, respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 563 xFetch = strncmp(dataStart, "GET /x", 6); // found GET /x , respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 564 // for example, in linux, xFetch can be used as: echo GET /x | nc 172.10.10.2
nixnax 93:9675adc36882 565 if( (httpGetRoot==0) || (xFetch==0) ) {
nixnax 89:2c8dd0c2a426 566 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 567 } else {
nixnax 89:2c8dd0c2a426 568 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 569 }
nixnax 83:cdcb81d1910f 570 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 571 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 572 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 573 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 574 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 575 nHeader=n; // size of HTTP header
nixnax 93:9675adc36882 576 if( httpGetRoot == 0 ) {
nixnax 83:cdcb81d1910f 577 // this is where we insert our web page into the buffer
nixnax 93:9675adc36882 578 //n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 93:9675adc36882 579 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 93:9675adc36882 580 n = n + sizeof(rootWebPage);
nixnax 85:53e57ff1cf05 581 } else {
nixnax 106:d14e6b597ca3 582 if (xFetch == 0) { // the 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 98:3babad0d1bd4 590 #define BENCHMARK_USING_BROWSER_NO /* set to _YES if you want to use your browser as a benchmark tool of http fetches */
nixnax 98:3babad0d1bd4 591 #ifndef BENCHMARK_USING_BROWSER_NO
nixnax 98:3babad0d1bd4 592 // a small script that reloads the page after 10 ms - handy for benchmarking using your web browser
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
nixnax 98:3babad0d1bd4 625 n=n+sprintf(n+dataStart,"Got %04d bytes.\n",len); // report the number of bytes received
nixnax 98:3babad0d1bd4 626 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 627 if (v2) {
nixnax 98:3babad0d1bd4 628 debug("TCP response %d byes\n",n);
nixnax 98:3babad0d1bd4 629 }
nixnax 98:3babad0d1bd4 630 return n; // total byte size of our response
nixnax 98:3babad0d1bd4 631 }
nixnax 98:3babad0d1bd4 632
nixnax 29:30de79d658f6 633 void tcpHandler()
nixnax 29:30de79d658f6 634 {
nixnax 87:9f5ac1fabd95 635 // IP header
nixnax 87:9f5ac1fabd95 636
nixnax 26:11f4eb2663a7 637 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 638 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 639 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 640 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 641 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 642 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 643 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 644 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 645 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 646 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 647
nixnax 87:9f5ac1fabd95 648 // TCP header
nixnax 87:9f5ac1fabd95 649
nixnax 87:9f5ac1fabd95 650 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 651 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 652 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 653 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 654 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 655 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 656 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 657 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 658 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 659
nixnax 26:11f4eb2663a7 660 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 661 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 662 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 663
nixnax 87:9f5ac1fabd95 664 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 665 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 666 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 667
nixnax 85:53e57ff1cf05 668 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 669 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 670
nixnax 85:53e57ff1cf05 671 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 672 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 673
nixnax 29:30de79d658f6 674 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 675 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 676 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 677 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 678 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 679
nixnax 87:9f5ac1fabd95 680 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 681 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 682
nixnax 87:9f5ac1fabd95 683 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 684 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 685 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 686 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 687 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 688 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 689
nixnax 35:e7068df4d971 690 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 691 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 692 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 693
nixnax 97:bdf885e146dc 694 windowsizetcp[0]=2; // tco window size = 700
nixnax 97:bdf885e146dc 695 windowsizetcp[1]=0xbc; // tcp windows size = 700
nixnax 38:ab582987926e 696
nixnax 93:9675adc36882 697 int doFin = 0; // flag to see if we have to send an extra FIN message to shut down the link
nixnax 93:9675adc36882 698
nixnax 106:d14e6b597ca3 699 // A sparse TCP flag interpreter that implements stateless TCP connections
nixnax 77:abf92baebb42 700
nixnax 69:23f560087c16 701 switch ( flagsTCP ) {
nixnax 69:23f560087c16 702 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 703 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 704 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 705 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 706 break;
nixnax 77:abf92baebb42 707 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 98:3babad0d1bd4 708 if ( strncmp(tcpDataIn, "GET /", 5) == 0) { // check for an http GET command
nixnax 98:3babad0d1bd4 709 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing this TCP connection
nixnax 87:9f5ac1fabd95 710 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 98:3babad0d1bd4 711 } else {
nixnax 106:d14e6b597ca3 712 dataLen = tcpResponse(tcpDataOut,tcpDataSize); // not a web request, send a packet reporting number of received bytes
nixnax 69:23f560087c16 713 }
nixnax 69:23f560087c16 714 break;
nixnax 98:3babad0d1bd4 715 case TCP_FLAG_FIN | TCP_FLAG_PSH | TCP_FLAG_ACK:
nixnax 69:23f560087c16 716 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 93:9675adc36882 717 case TCP_FLAG_RST:
nixnax 85:53e57ff1cf05 718 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 719 break;
nixnax 98:3babad0d1bd4 720 case TCP_FLAG_FIN:
nixnax 98:3babad0d1bd4 721 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing the connection
nixnax 98:3babad0d1bd4 722 break;
nixnax 77:abf92baebb42 723 default:
nixnax 69:23f560087c16 724 return; // ignore remaining packets
nixnax 93:9675adc36882 725 } // switch
nixnax 77:abf92baebb42 726
nixnax 69:23f560087c16 727 // The TCP flag handling is now done
nixnax 105:45001195b325 728 // first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax 95:40af49390daf 729
nixnax 65:23b17c43aa0f 730 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 731 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 732 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 733 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 734
nixnax 60:2b770949c911 735 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 736 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 737 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 95:40af49390daf 738
nixnax 93:9675adc36882 739 sendTCP:
nixnax 106:d14e6b597ca3 740
nixnax 85:53e57ff1cf05 741 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 742 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 743 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 744 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 745
nixnax 85:53e57ff1cf05 746 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 747 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 748 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 749 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 750
nixnax 93:9675adc36882 751 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 752
nixnax 93:9675adc36882 753 // increment the ip ident number
nixnax 93:9675adc36882 754 ppp.ident++; // get next ident number for our packet
nixnax 93:9675adc36882 755 ident[0] = ppp.ident>>8;
nixnax 93:9675adc36882 756 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 757
nixnax 106:d14e6b597ca3 758 // Now we recalculate all the header sizes
nixnax 38:ab582987926e 759 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 760 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 761 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 762 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 763 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 764
nixnax 38:ab582987926e 765 // the header is all set up, now do the IP and TCP checksums
nixnax 61:b3c1a04efd0a 766 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 767 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 768 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 769
nixnax 64:677b9713a120 770 // 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 771 // 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 772
nixnax 87:9f5ac1fabd95 773 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 774 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 775 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 776 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 777 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 778 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 779 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 780
nixnax 61:b3c1a04efd0a 781 // pseudo-header built, now we can calculate TCP checksum
nixnax 29:30de79d658f6 782 checksumtcp[0]=0;
nixnax 29:30de79d658f6 783 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 784 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 785 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 786 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 787 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 95:40af49390daf 788
nixnax 93:9675adc36882 789 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 60:2b770949c911 790
nixnax 93:9675adc36882 791 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 792 doFin=0;
nixnax 93:9675adc36882 793 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // tell them we are also finished
nixnax 93:9675adc36882 794 goto sendTCP; // send our final packet for this conversation.
nixnax 93:9675adc36882 795 }
nixnax 83:cdcb81d1910f 796 dumpHeaderIP();
nixnax 95:40af49390daf 797 dumpHeaderTCP();
nixnax 29:30de79d658f6 798 }
nixnax 26:11f4eb2663a7 799
nixnax 29:30de79d658f6 800 void dumpDataTCP()
nixnax 29:30de79d658f6 801 {
nixnax 26:11f4eb2663a7 802 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 803 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 804 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 805 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 806 if (v1) {
nixnax 42:4de44be70bfd 807 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 808 }
nixnax 29:30de79d658f6 809 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 810 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 811 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 812 }
nixnax 29:30de79d658f6 813 }
nixnax 26:11f4eb2663a7 814
nixnax 29:30de79d658f6 815 void TCPpacket()
nixnax 29:30de79d658f6 816 {
nixnax 83:cdcb81d1910f 817 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 818 dumpHeaderTCP();
nixnax 77:abf92baebb42 819 if (v2) {
nixnax 77:abf92baebb42 820 dumpDataTCP();
nixnax 77:abf92baebb42 821 }
nixnax 26:11f4eb2663a7 822 tcpHandler();
nixnax 11:f58998c24f0b 823 }
nixnax 11:f58998c24f0b 824
nixnax 29:30de79d658f6 825 void otherProtocol()
nixnax 29:30de79d658f6 826 {
nixnax 64:677b9713a120 827 debug("Other IP protocol");
nixnax 29:30de79d658f6 828 }
nixnax 26:11f4eb2663a7 829
nixnax 29:30de79d658f6 830 void IPframe()
nixnax 29:30de79d658f6 831 {
nixnax 10:74f8233f72c0 832 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 833 switch (protocol) {
nixnax 29:30de79d658f6 834 case 1:
nixnax 29:30de79d658f6 835 ICMPpacket();
nixnax 29:30de79d658f6 836 break;
nixnax 29:30de79d658f6 837 case 2:
nixnax 29:30de79d658f6 838 IGMPpacket();
nixnax 29:30de79d658f6 839 break;
nixnax 29:30de79d658f6 840 case 17:
nixnax 29:30de79d658f6 841 UDPpacket();
nixnax 29:30de79d658f6 842 break;
nixnax 29:30de79d658f6 843 case 6:
nixnax 29:30de79d658f6 844 TCPpacket();
nixnax 29:30de79d658f6 845 break;
nixnax 29:30de79d658f6 846 default:
nixnax 29:30de79d658f6 847 otherProtocol();
nixnax 29:30de79d658f6 848 }
nixnax 29:30de79d658f6 849 }
nixnax 9:0992486d4a30 850
nixnax 29:30de79d658f6 851 void LCPconfReq()
nixnax 29:30de79d658f6 852 {
nixnax 64:677b9713a120 853 debug("LCP Config ");
nixnax 9:0992486d4a30 854 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 855 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 856 debug("Reject\n");
nixnax 93:9675adc36882 857 send_pppFrame();
nixnax 9:0992486d4a30 858 } else {
nixnax 9:0992486d4a30 859 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 860 debug("Ack\n");
nixnax 93:9675adc36882 861 send_pppFrame();
nixnax 64:677b9713a120 862 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 863 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 864 send_pppFrame();
nixnax 9:0992486d4a30 865 }
nixnax 9:0992486d4a30 866 }
nixnax 9:0992486d4a30 867
nixnax 29:30de79d658f6 868 void LCPconfAck()
nixnax 29:30de79d658f6 869 {
nixnax 64:677b9713a120 870 debug("LCP Ack\n");
nixnax 29:30de79d658f6 871 }
nixnax 9:0992486d4a30 872
nixnax 29:30de79d658f6 873 void LCPend()
nixnax 29:30de79d658f6 874 {
nixnax 29:30de79d658f6 875 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 876 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 877 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 878 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 879 debug("LCP End\n");
nixnax 9:0992486d4a30 880 }
nixnax 9:0992486d4a30 881
nixnax 29:30de79d658f6 882 void LCPother()
nixnax 29:30de79d658f6 883 {
nixnax 64:677b9713a120 884 debug("LCP Other\n");
nixnax 95:40af49390daf 885 dumpPPPFrame();
nixnax 29:30de79d658f6 886 }
nixnax 29:30de79d658f6 887
nixnax 29:30de79d658f6 888 void LCPframe()
nixnax 29:30de79d658f6 889 {
nixnax 29:30de79d658f6 890 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 891 switch (code) {
nixnax 29:30de79d658f6 892 case 1:
nixnax 29:30de79d658f6 893 LCPconfReq();
nixnax 29:30de79d658f6 894 break; // config request
nixnax 29:30de79d658f6 895 case 2:
nixnax 29:30de79d658f6 896 LCPconfAck();
nixnax 29:30de79d658f6 897 break; // config ack
nixnax 29:30de79d658f6 898 case 5:
nixnax 29:30de79d658f6 899 LCPend();
nixnax 29:30de79d658f6 900 break; // end connection
nixnax 29:30de79d658f6 901 default:
nixnax 29:30de79d658f6 902 LCPother();
nixnax 29:30de79d658f6 903 }
nixnax 9:0992486d4a30 904 }
nixnax 9:0992486d4a30 905
nixnax 29:30de79d658f6 906 void discardedFrame()
nixnax 29:30de79d658f6 907 {
nixnax 29:30de79d658f6 908 if (v0) {
nixnax 71:965619fedb3a 909 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 910 }
nixnax 9:0992486d4a30 911 }
nixnax 9:0992486d4a30 912
nixnax 29:30de79d658f6 913 void determinePacketType()
nixnax 29:30de79d658f6 914 {
nixnax 29:30de79d658f6 915 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 916 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 917 return;
nixnax 29:30de79d658f6 918 }
nixnax 29:30de79d658f6 919 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 920 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 921 return;
nixnax 29:30de79d658f6 922 }
nixnax 29:30de79d658f6 923 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 924 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 925 return;
nixnax 29:30de79d658f6 926 }
nixnax 9:0992486d4a30 927 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 928 switch (packetType) {
nixnax 29:30de79d658f6 929 case 0xc0:
nixnax 29:30de79d658f6 930 LCPframe();
nixnax 29:30de79d658f6 931 break; // link control
nixnax 29:30de79d658f6 932 case 0x80:
nixnax 29:30de79d658f6 933 IPCPframe();
nixnax 29:30de79d658f6 934 break; // IP control
nixnax 29:30de79d658f6 935 case 0x00:
nixnax 29:30de79d658f6 936 IPframe();
nixnax 29:30de79d658f6 937 break; // IP itself
nixnax 29:30de79d658f6 938 default:
nixnax 29:30de79d658f6 939 discardedFrame();
nixnax 9:0992486d4a30 940 }
nixnax 29:30de79d658f6 941 }
nixnax 9:0992486d4a30 942
nixnax 50:ad4e7c3c88e5 943 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 944 {
nixnax 85:53e57ff1cf05 945 while(1) {
nixnax 93:9675adc36882 946 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 947 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 948 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 949 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 950 if (rx==FRAME_7E) {
nixnax 106:d14e6b597ca3 951 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 106:d14e6b597ca3 952 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 106:d14e6b597ca3 953 ppp.rx.rtail = ppp.rx.tail;
nixnax 106:d14e6b597ca3 954 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 106:d14e6b597ca3 955 break;
nixnax 50:ad4e7c3c88e5 956 }
nixnax 50:ad4e7c3c88e5 957 }
nixnax 85:53e57ff1cf05 958 }
nixnax 50:ad4e7c3c88e5 959 }
nixnax 50:ad4e7c3c88e5 960
nixnax 29:30de79d658f6 961 void scanForConnectString()
nixnax 29:30de79d658f6 962 {
nixnax 81:9ede60e9a2c8 963 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 964 fillbuf();
nixnax 81:9ede60e9a2c8 965 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 106:d14e6b597ca3 966 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax 81:9ede60e9a2c8 967 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 968 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 969 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 970 if (found1 != NULL) {
nixnax 81:9ede60e9a2c8 971 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 106:d14e6b597ca3 972 led1Toggle();
nixnax 81:9ede60e9a2c8 973 pc.puts("CLIENTSERVER");
nixnax 106:d14e6b597ca3 974 if (v0) debug("Found connect string \"CLIENT\"\n");
nixnax 81:9ede60e9a2c8 975 }
nixnax 81:9ede60e9a2c8 976 if (found2 != NULL) {
nixnax 81:9ede60e9a2c8 977 if (v0) debug("Found HDLC frame start (7E)\n");
nixnax 81:9ede60e9a2c8 978 }
nixnax 71:965619fedb3a 979 ppp.online=1; // we are connected, so stop looking for the string
nixnax 9:0992486d4a30 980 }
nixnax 9:0992486d4a30 981 }
nixnax 103:4f5512dd11cf 982 }
nixnax 81:9ede60e9a2c8 983
nixnax 9:0992486d4a30 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 }