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@103:4f5512dd11cf, 2017-07-31 (annotated)

Committer:
nixnax
Date:
Mon Jul 31 08:14:13 2017 +0000
Revision:
103:4f5512dd11cf
Parent:
102:a89c55672170
Child:
104:b1280b084f75
Improved IPCP response.

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 81:9ede60e9a2c8 33 #include "mbed.h"
nixnax 66:f005b9fdf4d1 34
nixnax 93:9675adc36882 35 // The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 36 // 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 37 #define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax 0:2cf4880c312a 38
nixnax 41:e58a5a09f411 39 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 40
nixnax 93:9675adc36882 41 // here we define the OPTIONAL, second debug serial port for the various target boards
nixnax 93:9675adc36882 42 // 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 43 #if defined(TARGET_LPC1768)
nixnax 85:53e57ff1cf05 44 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 45 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE)
nixnax 85:53e57ff1cf05 46 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 47 #else
nixnax 85:53e57ff1cf05 48 #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 49 #endif
nixnax 85:53e57ff1cf05 50
nixnax 93:9675adc36882 51 #define debug(x...) xx.printf (x)
nixnax 85:53e57ff1cf05 52
nixnax 41:e58a5a09f411 53 #else
nixnax 42:4de44be70bfd 54 #define debug(x...) {}
nixnax 41:e58a5a09f411 55 #endif
nixnax 41:e58a5a09f411 56
nixnax 93:9675adc36882 57 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 90:55e0f243a7ce 58 #define v0 0
nixnax 93:9675adc36882 59 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 60 #define v1 0
nixnax 93:9675adc36882 61 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 77:abf92baebb42 62 #define v2 0
nixnax 29:30de79d658f6 63
nixnax 93:9675adc36882 64 // this is the webpage we serve when we get an HTTP request to root (/)
nixnax 93:9675adc36882 65 // keep size under ~900 bytes to fit into a single PPP packet
nixnax 93:9675adc36882 66 const static char rootWebPage[] = "\
nixnax 66:f005b9fdf4d1 67 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 68 <html>\
nixnax 66:f005b9fdf4d1 69 <head>\
nixnax 66:f005b9fdf4d1 70 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 71 <script>\
nixnax 66:f005b9fdf4d1 72 window.onload=function(){\
nixnax 66:f005b9fdf4d1 73 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 74 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 75 </script>\
nixnax 66:f005b9fdf4d1 76 </head>\
nixnax 66:f005b9fdf4d1 77 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 78 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 79 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 80 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 81 </body>\
nixnax 69:23f560087c16 82 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 83
nixnax 73:2f56ec87dbe9 84 // 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 85 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 86 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 87 // See instructions at the top.
nixnax 73:2f56ec87dbe9 88 // 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 89 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 90
nixnax 29:30de79d658f6 91 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 92
nixnax 66:f005b9fdf4d1 93 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 94 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 95
nixnax 29:30de79d658f6 96 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 97 struct pppType {
nixnax 38:ab582987926e 98 int online; // we hunt for a PPP connection if this is zero
nixnax 87:9f5ac1fabd95 99 unsigned int ident; // our IP ident value
nixnax 38:ab582987926e 100 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 101 int ledState; // state of LED1
nixnax 98:3babad0d1bd4 102 int httpPageCount;
nixnax 4:a469050d5b80 103 struct {
nixnax 81:9ede60e9a2c8 104 #define RXBUFLEN (1<<14)
nixnax 93:9675adc36882 105 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 8192 bytes)
nixnax 85:53e57ff1cf05 106 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 93:9675adc36882 107 int head;
nixnax 93:9675adc36882 108 int tail;
nixnax 95:40af49390daf 109 int rtail;
nixnax 93:9675adc36882 110 int buflevel;
nixnax 38:ab582987926e 111 } rx; // serial port objects
nixnax 4:a469050d5b80 112 struct {
nixnax 38:ab582987926e 113 int len; // number of bytes in buffer
nixnax 38:ab582987926e 114 int crc; // PPP CRC (frame check)
nixnax 77:abf92baebb42 115 #define TCP_max_size 3300
nixnax 77:abf92baebb42 116 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 117 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 118 struct {
nixnax 50:ad4e7c3c88e5 119 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 120 int frameEndIndex; // frame end marker
nixnax 81:9ede60e9a2c8 121 int frameFound; // we have found at least one start of frame already
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.frameFound=0;
nixnax 81:9ede60e9a2c8 140 ppp.hdlc.frameStartIndex=0;
nixnax 98:3babad0d1bd4 141 ppp.httpPageCount=0;
nixnax 29:30de79d658f6 142 }
nixnax 26:11f4eb2663a7 143
nixnax 43:aa57db08995d 144 void led1Toggle()
nixnax 43:aa57db08995d 145 {
nixnax 43:aa57db08995d 146 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 93:9675adc36882 147 led1 = ppp.ledState; // toggle led
nixnax 43:aa57db08995d 148 }
nixnax 43:aa57db08995d 149
nixnax 29:30de79d658f6 150 void crcReset()
nixnax 29:30de79d658f6 151 {
nixnax 29:30de79d658f6 152 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 153 }
nixnax 4:a469050d5b80 154
nixnax 29:30de79d658f6 155 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 156 {
nixnax 29:30de79d658f6 157 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 158 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 159 x>>=1;
nixnax 29:30de79d658f6 160 }
nixnax 29:30de79d658f6 161 }
nixnax 29:30de79d658f6 162
nixnax 29:30de79d658f6 163 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 164 {
nixnax 31:e000c1b9c565 165 crcReset();
nixnax 31:e000c1b9c565 166 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 167 return ppp.crc;
nixnax 29:30de79d658f6 168 }
nixnax 0:2cf4880c312a 169
nixnax 85:53e57ff1cf05 170 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 171 void fillbuf()
nixnax 0:2cf4880c312a 172 {
nixnax 85:53e57ff1cf05 173 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 174 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 93:9675adc36882 175 if ( hd == ppp.rx.rtail ) {
nixnax 85:53e57ff1cf05 176 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 177 return;
nixnax 83:cdcb81d1910f 178 }
nixnax 17:4918c893d802 179 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 180 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 181 ppp.rx.buflevel++;
nixnax 15:b0154c910143 182 }
nixnax 0:2cf4880c312a 183 }
nixnax 0:2cf4880c312a 184
nixnax 85:53e57ff1cf05 185 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 186 {
nixnax 43:aa57db08995d 187 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 188 return emptyStatus;
nixnax 0:2cf4880c312a 189 }
nixnax 0:2cf4880c312a 190
nixnax 85:53e57ff1cf05 191 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 192 {
nixnax 63:9253b0e1b7d8 193 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 194 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 195 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 196 return x;
nixnax 0:2cf4880c312a 197 }
nixnax 0:2cf4880c312a 198
nixnax 95:40af49390daf 199 // Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 95:40af49390daf 200 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 95:40af49390daf 201 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 95:40af49390daf 202 void dumpPPPFrame()
nixnax 95:40af49390daf 203 {
nixnax 95:40af49390daf 204 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 95:40af49390daf 205 debug(" CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 95:40af49390daf 206 }
nixnax 95:40af49390daf 207
nixnax 50:ad4e7c3c88e5 208 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 209 {
nixnax 38:ab582987926e 210 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 211 if(start==end) {
nixnax 29:30de79d658f6 212 return;
nixnax 29:30de79d658f6 213 }
nixnax 9:0992486d4a30 214 crcReset();
nixnax 9:0992486d4a30 215 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 216 ppp.pkt.len=0;
nixnax 9:0992486d4a30 217 int unstuff=0;
nixnax 17:4918c893d802 218 int idx = start;
nixnax 17:4918c893d802 219 while(1) {
nixnax 9:0992486d4a30 220 if (unstuff==0) {
nixnax 72:ad3d12753acf 221 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 222 else {
nixnax 72:ad3d12753acf 223 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 224 ppp.pkt.len++;
nixnax 29:30de79d658f6 225 dest++;
nixnax 72:ad3d12753acf 226 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 227 }
nixnax 66:f005b9fdf4d1 228 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 229 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 230 ppp.pkt.len++;
nixnax 29:30de79d658f6 231 dest++;
nixnax 72:ad3d12753acf 232 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 233 unstuff=0;
nixnax 9:0992486d4a30 234 }
nixnax 81:9ede60e9a2c8 235 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 236 if (idx == end) break;
nixnax 9:0992486d4a30 237 }
nixnax 29:30de79d658f6 238 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 239 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 240 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 241 determinePacketType();
nixnax 90:55e0f243a7ce 242 } else {
nixnax 95:40af49390daf 243 if (0) { // don't normally report FCS because windows early-terminates packets, and early-terminated packets all have FCS errors.
nixnax 95:40af49390daf 244 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 245 }
nixnax 9:0992486d4a30 246 }
nixnax 9:0992486d4a30 247 }
nixnax 9:0992486d4a30 248
nixnax 29:30de79d658f6 249 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 250 {
nixnax 29:30de79d658f6 251 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 252 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 253 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 254 } else {
nixnax 29:30de79d658f6 255 pc.putc(ch);
nixnax 29:30de79d658f6 256 }
nixnax 11:f58998c24f0b 257 }
nixnax 9:0992486d4a30 258
nixnax 93:9675adc36882 259 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 260 {
nixnax 17:4918c893d802 261 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 262 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 263 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 264 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 95:40af49390daf 265 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 266 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 95:40af49390daf 267
nixnax 93:9675adc36882 268 if((i&0x7f)==0) fillbuf(); // handle received characters very every 128 sent
nixnax 93:9675adc36882 269 }
nixnax 16:cb0b80c24ba2 270 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 271 }
nixnax 9:0992486d4a30 272
nixnax 93:9675adc36882 273 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 274 {
nixnax 93:9675adc36882 275 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 276 ppp.pkt.buf[4]=2; // change code to ack
nixnax 93:9675adc36882 277 send_pppFrame(); // simply acknowledge everything they ask for
nixnax 93:9675adc36882 278 debug("Our IPCP Ask\n");
nixnax 92:cb962b365cce 279 ppp.pkt.buf[4]=1; // change code to request
nixnax 103:4f5512dd11cf 280 if (ppp.pkt.buf[8]==3) { // check if this is an ip address request
nixnax 103:4f5512dd11cf 281 ppp.pkt.buf[13]++; // choose next ip address
nixnax 103:4f5512dd11cf 282 } else { // not an IP request, respond with empty request
nixnax 103:4f5512dd11cf 283 ppp.pkt.len=10; // shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax 103:4f5512dd11cf 284 ppp.pkt.buf[7]=4; // no options in this request
nixnax 103:4f5512dd11cf 285 }
nixnax 103:4f5512dd11cf 286 send_pppFrame(); // send our request
nixnax 9:0992486d4a30 287 }
nixnax 9:0992486d4a30 288
nixnax 93:9675adc36882 289 void ipcpAckHandler()
nixnax 29:30de79d658f6 290 {
nixnax 93:9675adc36882 291 debug("Their IPCP Grant\n");
nixnax 29:30de79d658f6 292 }
nixnax 9:0992486d4a30 293
nixnax 93:9675adc36882 294 void ipcpNackHandler()
nixnax 29:30de79d658f6 295 {
nixnax 93:9675adc36882 296 debug("Their IPCP Nack\n");
nixnax 29:30de79d658f6 297 }
nixnax 9:0992486d4a30 298
nixnax 93:9675adc36882 299 void ipcpDefaultHandler()
nixnax 29:30de79d658f6 300 {
nixnax 93:9675adc36882 301 debug("Their IPCP Other\n");
nixnax 29:30de79d658f6 302 }
nixnax 29:30de79d658f6 303
nixnax 29:30de79d658f6 304 void IPCPframe()
nixnax 29:30de79d658f6 305 {
nixnax 9:0992486d4a30 306 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 307 switch (code) {
nixnax 29:30de79d658f6 308 case 1:
nixnax 93:9675adc36882 309 ipcpConfigRequestHandler();
nixnax 29:30de79d658f6 310 break;
nixnax 29:30de79d658f6 311 case 2:
nixnax 93:9675adc36882 312 ipcpAckHandler();
nixnax 29:30de79d658f6 313 break;
nixnax 29:30de79d658f6 314 case 3:
nixnax 93:9675adc36882 315 ipcpNackHandler();
nixnax 29:30de79d658f6 316 break;
nixnax 29:30de79d658f6 317 default:
nixnax 93:9675adc36882 318 ipcpDefaultHandler();
nixnax 9:0992486d4a30 319 }
nixnax 29:30de79d658f6 320 }
nixnax 9:0992486d4a30 321
nixnax 29:30de79d658f6 322 void UDPpacket()
nixnax 29:30de79d658f6 323 {
nixnax 12:db0dc91f0231 324 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 325 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 326 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 327 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 328 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 329 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 330 #endif
nixnax 12:db0dc91f0231 331 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 332 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 333 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 334 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 335 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 336 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 337 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 338 #endif
nixnax 29:30de79d658f6 339 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 340 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 341 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 342 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 343 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 344 int printSize = udpLength;
nixnax 29:30de79d658f6 345 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 346 if (v1) {
nixnax 29:30de79d658f6 347 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 348 char ch = udpInf[i];
nixnax 29:30de79d658f6 349 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 350 debug("%c", ch);
nixnax 29:30de79d658f6 351 } else {
nixnax 64:677b9713a120 352 debug("_");
nixnax 29:30de79d658f6 353 }
nixnax 29:30de79d658f6 354 }
nixnax 29:30de79d658f6 355 }
nixnax 83:cdcb81d1910f 356 if (v0) debug("\n");
nixnax 12:db0dc91f0231 357 }
nixnax 11:f58998c24f0b 358
nixnax 76:00e208cceb8b 359 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 360 {
nixnax 77:abf92baebb42 361
nixnax 75:0d513869231f 362 unsigned int sum=0;
nixnax 76:00e208cceb8b 363 unsigned char placeHolder;
nixnax 29:30de79d658f6 364 if (len&1) {
nixnax 76:00e208cceb8b 365 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 366 ptr[len]=0;
nixnax 29:30de79d658f6 367 }
nixnax 29:30de79d658f6 368 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 369 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 370 ptr++;
nixnax 76:00e208cceb8b 371 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 372 ptr++;
nixnax 76:00e208cceb8b 373 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 374 sum = sum + val;
nixnax 11:f58998c24f0b 375 }
nixnax 29:30de79d658f6 376 if (len&1) {
nixnax 76:00e208cceb8b 377 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 378 }
nixnax 76:00e208cceb8b 379 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 380 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 381 return ~sum;
nixnax 29:30de79d658f6 382 }
nixnax 11:f58998c24f0b 383
nixnax 29:30de79d658f6 384 void headerCheckSum()
nixnax 29:30de79d658f6 385 {
nixnax 11:f58998c24f0b 386 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 387 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 388 int sum=0;
nixnax 11:f58998c24f0b 389
nixnax 29:30de79d658f6 390 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 391 int hi = *ptr;
nixnax 29:30de79d658f6 392 ptr++;
nixnax 29:30de79d658f6 393 int lo = *ptr;
nixnax 29:30de79d658f6 394 ptr++;
nixnax 11:f58998c24f0b 395 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 396 sum = sum + val;
nixnax 11:f58998c24f0b 397 }
nixnax 11:f58998c24f0b 398 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 399 sum = ~sum;
nixnax 11:f58998c24f0b 400 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 401 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 402 }
nixnax 9:0992486d4a30 403
nixnax 29:30de79d658f6 404 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 405 {
nixnax 12:db0dc91f0231 406 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 407 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 408 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 409 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 410 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 411 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 412 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 413 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 414 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 415 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 416 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 417 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 418 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 419 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 420 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 421 #endif
nixnax 81:9ede60e9a2c8 422 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 423 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 424 char src[4];
nixnax 29:30de79d658f6 425 char dst[4];
nixnax 12:db0dc91f0231 426 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 427 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 428 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 429 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 430 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 431 chkSum[0]=0;
nixnax 29:30de79d658f6 432 chkSum[1]=0;
nixnax 12:db0dc91f0231 433 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 434 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 435 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 436 icmpSum[0]=0;
nixnax 29:30de79d658f6 437 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 438 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 439 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 440 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 441 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 442
nixnax 16:cb0b80c24ba2 443 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 444 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 445 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 446 if (v0) {
nixnax 29:30de79d658f6 447 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 448 char ch = icmpData[i];
nixnax 29:30de79d658f6 449 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 450 debug("%c",ch);
nixnax 29:30de79d658f6 451 } else {
nixnax 64:677b9713a120 452 debug("_");
nixnax 29:30de79d658f6 453 }
nixnax 29:30de79d658f6 454 }
nixnax 64:677b9713a120 455 debug("\n");
nixnax 29:30de79d658f6 456 }
nixnax 93:9675adc36882 457 send_pppFrame(); // reply to the ping
nixnax 29:30de79d658f6 458
nixnax 12:db0dc91f0231 459 } else {
nixnax 29:30de79d658f6 460 if (v0) {
nixnax 42:4de44be70bfd 461 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 462 }
nixnax 11:f58998c24f0b 463 }
nixnax 11:f58998c24f0b 464 }
nixnax 11:f58998c24f0b 465
nixnax 29:30de79d658f6 466 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 467 {
nixnax 29:30de79d658f6 468 if (v0) {
nixnax 42:4de44be70bfd 469 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 470 }
nixnax 29:30de79d658f6 471 }
nixnax 11:f58998c24f0b 472
nixnax 29:30de79d658f6 473 void dumpHeaderIP ()
nixnax 29:30de79d658f6 474 {
nixnax 95:40af49390daf 475 if (v0) {
nixnax 95:40af49390daf 476 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 477 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 478 char * version = ipPkt; // top 4 bits
nixnax 95:40af49390daf 479 char * ihl = ipPkt; // bottom 4 bits
nixnax 95:40af49390daf 480 char * dscp = ipPkt+1; // top 6 bits
nixnax 95:40af49390daf 481 char * ecn = ipPkt+1; // lower 2 bits
nixnax 95:40af49390daf 482 char * pktLen = ipPkt+2; // 2 bytes
nixnax 95:40af49390daf 483 char * ident = ipPkt+4; // 2 bytes
nixnax 95:40af49390daf 484 char * flags = ipPkt+6; // 2 bits
nixnax 95:40af49390daf 485 char * ttl = ipPkt+8; // 1 byte
nixnax 95:40af49390daf 486 char * protocol = ipPkt+9; // 1 byte
nixnax 95:40af49390daf 487 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 488 #endif
nixnax 95:40af49390daf 489 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 95:40af49390daf 490 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 491
nixnax 55:43faae812be3 492 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 493 int versionIP = (version[0]>>4)&0xf;
nixnax 95:40af49390daf 494 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 95:40af49390daf 495 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 95:40af49390daf 496 int ecnIP = ecn[0]&3;
nixnax 95:40af49390daf 497 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 95:40af49390daf 498 int identIP = (ident[0]<<8)|ident[1];
nixnax 95:40af49390daf 499 int flagsIP = flags[0]>>14&3;
nixnax 95:40af49390daf 500 int ttlIP = ttl[0];
nixnax 95:40af49390daf 501 int protocolIP = protocol[0];
nixnax 95:40af49390daf 502 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 503 #endif
nixnax 55:43faae812be3 504
nixnax 95:40af49390daf 505 char srcIP [16];
nixnax 95:40af49390daf 506 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 95:40af49390daf 507 char dstIP [16];
nixnax 95:40af49390daf 508 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 95:40af49390daf 509 debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 95:40af49390daf 510 debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 95:40af49390daf 511 }
nixnax 29:30de79d658f6 512 }
nixnax 26:11f4eb2663a7 513
nixnax 29:30de79d658f6 514 void dumpHeaderTCP()
nixnax 29:30de79d658f6 515 {
nixnax 83:cdcb81d1910f 516 if( v0 ) {
nixnax 81:9ede60e9a2c8 517 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 518 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 519 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 520 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 521 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 522 #endif
nixnax 81:9ede60e9a2c8 523 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 524 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 525 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 526 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 527 #endif
nixnax 81:9ede60e9a2c8 528 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 529
nixnax 81:9ede60e9a2c8 530 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 531 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 532 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 533
nixnax 81:9ede60e9a2c8 534 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 535 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 536 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 537 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 538 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 539 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 540 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 541 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 542 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 543 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 544 }
nixnax 29:30de79d658f6 545 }
nixnax 29:30de79d658f6 546
nixnax 68:0b74763ae67f 547 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 548 {
nixnax 67:a63e3486bcda 549 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 550 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 551 int contentLengthStart; // index where HTML starts
nixnax 93:9675adc36882 552 int xFetch, httpGetRoot; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 553
nixnax 98:3babad0d1bd4 554 ppp.httpPageCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 555
nixnax 98:3babad0d1bd4 556 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found GET, respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 557 xFetch = strncmp(dataStart, "GET /x", 6); // found GET /x , respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 558 // for example, in linux, xFetch can be used as: echo GET /x | nc 172.10.10.2
nixnax 93:9675adc36882 559 if( (httpGetRoot==0) || (xFetch==0) ) {
nixnax 89:2c8dd0c2a426 560 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 561 } else {
nixnax 89:2c8dd0c2a426 562 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 563 }
nixnax 83:cdcb81d1910f 564 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 565 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 566 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 567 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 568 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 569 nHeader=n; // size of HTTP header
nixnax 93:9675adc36882 570 if( httpGetRoot == 0 ) {
nixnax 83:cdcb81d1910f 571 // this is where we insert our web page into the buffer
nixnax 93:9675adc36882 572 //n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 93:9675adc36882 573 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 93:9675adc36882 574 n = n + sizeof(rootWebPage);
nixnax 85:53e57ff1cf05 575 } else {
nixnax 89:2c8dd0c2a426 576 if (xFetch == 0) {
nixnax 89:2c8dd0c2a426 577
nixnax 89:2c8dd0c2a426 578 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 89:2c8dd0c2a426 579 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 89:2c8dd0c2a426 580 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 89:2c8dd0c2a426 581 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed-ppp-blinky</title>"); // html title (W3C.org required element)
nixnax 98:3babad0d1bd4 582 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.httpPageCount); // body = the http frame count
nixnax 89:2c8dd0c2a426 583 #else
nixnax 98:3babad0d1bd4 584 #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 585 #ifndef BENCHMARK_USING_BROWSER_NO
nixnax 98:3babad0d1bd4 586 // a small script that reloads the page after 10 ms - handy for benchmarking using your web browser
nixnax 98:3babad0d1bd4 587 n=n+sprintf(n+dataStart, "<script>setTimeout(function(){location.reload();},10);</script><body>%d</body>",ppp.httpPageCount);
nixnax 98:3babad0d1bd4 588 #else
nixnax 98:3babad0d1bd4 589 n=n+sprintf(n+dataStart,"%d",ppp.httpPageCount); // not valid html but fast, most browsers and curl are ok with it
nixnax 98:3babad0d1bd4 590 #endif
nixnax 89:2c8dd0c2a426 591 #endif
nixnax 89:2c8dd0c2a426 592
nixnax 89:2c8dd0c2a426 593 } else {
nixnax 89:2c8dd0c2a426 594 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 89:2c8dd0c2a426 595 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky-mbed</title>"); // html title (required element)
nixnax 89:2c8dd0c2a426 596 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 89:2c8dd0c2a426 597 }
nixnax 83:cdcb81d1910f 598 }
nixnax 87:9f5ac1fabd95 599 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 600 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 601
nixnax 83:cdcb81d1910f 602 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 603 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 604 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 605 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 606
nixnax 77:abf92baebb42 607 if (v2) {
nixnax 77:abf92baebb42 608 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 609 }
nixnax 67:a63e3486bcda 610 return n; // total byte size of our response
nixnax 67:a63e3486bcda 611 }
nixnax 67:a63e3486bcda 612
nixnax 98:3babad0d1bd4 613 // if not an http response we just report the number of bytes received
nixnax 98:3babad0d1bd4 614 // this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax 98:3babad0d1bd4 615 int tcpResponse(char * dataStart, int len)
nixnax 98:3babad0d1bd4 616 {
nixnax 98:3babad0d1bd4 617 int n=0; // number of bytes we have printed so far
nixnax 98:3babad0d1bd4 618
nixnax 98:3babad0d1bd4 619 n=n+sprintf(n+dataStart,"Got %04d bytes.\n",len); // report the number of bytes received
nixnax 98:3babad0d1bd4 620 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 621 if (v2) {
nixnax 98:3babad0d1bd4 622 debug("TCP response %d byes\n",n);
nixnax 98:3babad0d1bd4 623 }
nixnax 98:3babad0d1bd4 624 return n; // total byte size of our response
nixnax 98:3babad0d1bd4 625 }
nixnax 98:3babad0d1bd4 626
nixnax 29:30de79d658f6 627 void tcpHandler()
nixnax 29:30de79d658f6 628 {
nixnax 87:9f5ac1fabd95 629 // IP header
nixnax 87:9f5ac1fabd95 630
nixnax 26:11f4eb2663a7 631 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 632 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 633 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 634 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 635 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 636 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 637 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 638 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 639 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 640 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 641
nixnax 87:9f5ac1fabd95 642 // TCP header
nixnax 87:9f5ac1fabd95 643
nixnax 87:9f5ac1fabd95 644 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 645 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 646 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 647 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 648 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 649 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 650 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 651 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 652 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 653
nixnax 26:11f4eb2663a7 654 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 655 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 656 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 657
nixnax 87:9f5ac1fabd95 658 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 659 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 660 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 661
nixnax 85:53e57ff1cf05 662 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 663 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 664
nixnax 85:53e57ff1cf05 665 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 666 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 667
nixnax 29:30de79d658f6 668 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 669 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 670 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 671 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 672 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 673
nixnax 87:9f5ac1fabd95 674 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 675 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 676
nixnax 87:9f5ac1fabd95 677 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 678 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 679 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 680 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 681 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 682 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 683
nixnax 35:e7068df4d971 684 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 685 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 686 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 687
nixnax 97:bdf885e146dc 688 windowsizetcp[0]=2; // tco window size = 700
nixnax 97:bdf885e146dc 689 windowsizetcp[1]=0xbc; // tcp windows size = 700
nixnax 38:ab582987926e 690
nixnax 93:9675adc36882 691 int doFin = 0; // flag to see if we have to send an extra FIN message to shut down the link
nixnax 93:9675adc36882 692
nixnax 69:23f560087c16 693 // A sparse TCP flag interpreter that implements simple TCP connections from a single source
nixnax 69:23f560087c16 694 // Clients are allowed ONE push packet, after which the link is closed with a FIN flag in the ACK packet
nixnax 69:23f560087c16 695 // This strategy allows web browsers, netcat and curl to work ok while keeping the state machine simple
nixnax 77:abf92baebb42 696
nixnax 69:23f560087c16 697 switch ( flagsTCP ) {
nixnax 69:23f560087c16 698 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 699 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 700 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 701 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 702 break;
nixnax 77:abf92baebb42 703 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 98:3babad0d1bd4 704 if ( strncmp(tcpDataIn, "GET /", 5) == 0) { // check for an http GET command
nixnax 98:3babad0d1bd4 705 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing this TCP connection
nixnax 87:9f5ac1fabd95 706 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 98:3babad0d1bd4 707 } else {
nixnax 98:3babad0d1bd4 708 dataLen = tcpResponse(tcpDataOut,tcpDataSize); // not a web request, just report number of received bytes
nixnax 69:23f560087c16 709 }
nixnax 69:23f560087c16 710 break;
nixnax 98:3babad0d1bd4 711 case TCP_FLAG_FIN | TCP_FLAG_PSH | TCP_FLAG_ACK:
nixnax 69:23f560087c16 712 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 93:9675adc36882 713 case TCP_FLAG_RST:
nixnax 85:53e57ff1cf05 714 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 715 break;
nixnax 98:3babad0d1bd4 716 case TCP_FLAG_FIN:
nixnax 98:3babad0d1bd4 717 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing the connection
nixnax 98:3babad0d1bd4 718 break;
nixnax 77:abf92baebb42 719 default:
nixnax 69:23f560087c16 720 return; // ignore remaining packets
nixnax 93:9675adc36882 721 } // switch
nixnax 77:abf92baebb42 722
nixnax 69:23f560087c16 723 // The TCP flag handling is now done
nixnax 93:9675adc36882 724 // first we swap sourc and destination TCP addresses and insert the new ack and seq numbers
nixnax 95:40af49390daf 725
nixnax 65:23b17c43aa0f 726 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 727 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 728 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 729 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 730
nixnax 60:2b770949c911 731 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 732 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 733 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 95:40af49390daf 734
nixnax 93:9675adc36882 735 sendTCP:
nixnax 85:53e57ff1cf05 736 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 737 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 738 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 739 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 740
nixnax 85:53e57ff1cf05 741 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 742 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 743 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 744 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 745
nixnax 93:9675adc36882 746 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 747
nixnax 93:9675adc36882 748 // increment the ip ident number
nixnax 93:9675adc36882 749 ppp.ident++; // get next ident number for our packet
nixnax 93:9675adc36882 750 ident[0] = ppp.ident>>8;
nixnax 93:9675adc36882 751 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 752
nixnax 93:9675adc36882 753 // Now we recalculate all the header sizes, and do the IP and TCP checksums
nixnax 38:ab582987926e 754 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 755 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 756 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 757 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 758 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 759
nixnax 38:ab582987926e 760 // the header is all set up, now do the IP and TCP checksums
nixnax 61:b3c1a04efd0a 761 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 762 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 763 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 764
nixnax 64:677b9713a120 765 // 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 766 // 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 767
nixnax 87:9f5ac1fabd95 768 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 769 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 770 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 771 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 772 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 773 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 774 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 775
nixnax 61:b3c1a04efd0a 776 // pseudo-header built, now we can calculate TCP checksum
nixnax 29:30de79d658f6 777 checksumtcp[0]=0;
nixnax 29:30de79d658f6 778 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 779 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 780 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 781 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 782 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 95:40af49390daf 783
nixnax 93:9675adc36882 784 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 60:2b770949c911 785
nixnax 93:9675adc36882 786 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 787 doFin=0;
nixnax 93:9675adc36882 788 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // tell them we are also finished
nixnax 93:9675adc36882 789 goto sendTCP; // send our final packet for this conversation.
nixnax 93:9675adc36882 790 }
nixnax 83:cdcb81d1910f 791 dumpHeaderIP();
nixnax 95:40af49390daf 792 dumpHeaderTCP();
nixnax 29:30de79d658f6 793 }
nixnax 26:11f4eb2663a7 794
nixnax 29:30de79d658f6 795 void dumpDataTCP()
nixnax 29:30de79d658f6 796 {
nixnax 26:11f4eb2663a7 797 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 798 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 799 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 800 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 801 if (v1) {
nixnax 42:4de44be70bfd 802 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 803 }
nixnax 29:30de79d658f6 804 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 805 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 806 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 807 }
nixnax 29:30de79d658f6 808 }
nixnax 26:11f4eb2663a7 809
nixnax 29:30de79d658f6 810 void TCPpacket()
nixnax 29:30de79d658f6 811 {
nixnax 83:cdcb81d1910f 812 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 813 dumpHeaderTCP();
nixnax 77:abf92baebb42 814 if (v2) {
nixnax 77:abf92baebb42 815 dumpDataTCP();
nixnax 77:abf92baebb42 816 }
nixnax 26:11f4eb2663a7 817 tcpHandler();
nixnax 11:f58998c24f0b 818 }
nixnax 11:f58998c24f0b 819
nixnax 29:30de79d658f6 820 void otherProtocol()
nixnax 29:30de79d658f6 821 {
nixnax 64:677b9713a120 822 debug("Other IP protocol");
nixnax 29:30de79d658f6 823 }
nixnax 26:11f4eb2663a7 824
nixnax 29:30de79d658f6 825 void IPframe()
nixnax 29:30de79d658f6 826 {
nixnax 10:74f8233f72c0 827 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 828 switch (protocol) {
nixnax 29:30de79d658f6 829 case 1:
nixnax 29:30de79d658f6 830 ICMPpacket();
nixnax 29:30de79d658f6 831 break;
nixnax 29:30de79d658f6 832 case 2:
nixnax 29:30de79d658f6 833 IGMPpacket();
nixnax 29:30de79d658f6 834 break;
nixnax 29:30de79d658f6 835 case 17:
nixnax 29:30de79d658f6 836 UDPpacket();
nixnax 29:30de79d658f6 837 break;
nixnax 29:30de79d658f6 838 case 6:
nixnax 29:30de79d658f6 839 TCPpacket();
nixnax 29:30de79d658f6 840 break;
nixnax 29:30de79d658f6 841 default:
nixnax 29:30de79d658f6 842 otherProtocol();
nixnax 29:30de79d658f6 843 }
nixnax 29:30de79d658f6 844 }
nixnax 9:0992486d4a30 845
nixnax 29:30de79d658f6 846 void LCPconfReq()
nixnax 29:30de79d658f6 847 {
nixnax 64:677b9713a120 848 debug("LCP Config ");
nixnax 9:0992486d4a30 849 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 850 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 851 debug("Reject\n");
nixnax 93:9675adc36882 852 send_pppFrame();
nixnax 9:0992486d4a30 853 } else {
nixnax 9:0992486d4a30 854 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 855 debug("Ack\n");
nixnax 93:9675adc36882 856 send_pppFrame();
nixnax 64:677b9713a120 857 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 858 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 859 send_pppFrame();
nixnax 9:0992486d4a30 860 }
nixnax 9:0992486d4a30 861 }
nixnax 9:0992486d4a30 862
nixnax 29:30de79d658f6 863 void LCPconfAck()
nixnax 29:30de79d658f6 864 {
nixnax 64:677b9713a120 865 debug("LCP Ack\n");
nixnax 29:30de79d658f6 866 }
nixnax 9:0992486d4a30 867
nixnax 29:30de79d658f6 868 void LCPend()
nixnax 29:30de79d658f6 869 {
nixnax 29:30de79d658f6 870 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 871 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 872 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 873 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 874 debug("LCP End\n");
nixnax 9:0992486d4a30 875 }
nixnax 9:0992486d4a30 876
nixnax 29:30de79d658f6 877 void LCPother()
nixnax 29:30de79d658f6 878 {
nixnax 64:677b9713a120 879 debug("LCP Other\n");
nixnax 95:40af49390daf 880 dumpPPPFrame();
nixnax 29:30de79d658f6 881 }
nixnax 29:30de79d658f6 882
nixnax 29:30de79d658f6 883 void LCPframe()
nixnax 29:30de79d658f6 884 {
nixnax 29:30de79d658f6 885 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 886 switch (code) {
nixnax 29:30de79d658f6 887 case 1:
nixnax 29:30de79d658f6 888 LCPconfReq();
nixnax 29:30de79d658f6 889 break; // config request
nixnax 29:30de79d658f6 890 case 2:
nixnax 29:30de79d658f6 891 LCPconfAck();
nixnax 29:30de79d658f6 892 break; // config ack
nixnax 29:30de79d658f6 893 case 5:
nixnax 29:30de79d658f6 894 LCPend();
nixnax 29:30de79d658f6 895 break; // end connection
nixnax 29:30de79d658f6 896 default:
nixnax 29:30de79d658f6 897 LCPother();
nixnax 29:30de79d658f6 898 }
nixnax 9:0992486d4a30 899 }
nixnax 9:0992486d4a30 900
nixnax 29:30de79d658f6 901 void discardedFrame()
nixnax 29:30de79d658f6 902 {
nixnax 29:30de79d658f6 903 if (v0) {
nixnax 71:965619fedb3a 904 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 905 }
nixnax 9:0992486d4a30 906 }
nixnax 9:0992486d4a30 907
nixnax 29:30de79d658f6 908 void determinePacketType()
nixnax 29:30de79d658f6 909 {
nixnax 29:30de79d658f6 910 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 911 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 912 return;
nixnax 29:30de79d658f6 913 }
nixnax 29:30de79d658f6 914 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 915 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 916 return;
nixnax 29:30de79d658f6 917 }
nixnax 29:30de79d658f6 918 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 919 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 920 return;
nixnax 29:30de79d658f6 921 }
nixnax 9:0992486d4a30 922 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 923 switch (packetType) {
nixnax 29:30de79d658f6 924 case 0xc0:
nixnax 29:30de79d658f6 925 LCPframe();
nixnax 29:30de79d658f6 926 break; // link control
nixnax 29:30de79d658f6 927 case 0x80:
nixnax 29:30de79d658f6 928 IPCPframe();
nixnax 29:30de79d658f6 929 break; // IP control
nixnax 29:30de79d658f6 930 case 0x00:
nixnax 29:30de79d658f6 931 IPframe();
nixnax 29:30de79d658f6 932 break; // IP itself
nixnax 29:30de79d658f6 933 default:
nixnax 29:30de79d658f6 934 discardedFrame();
nixnax 9:0992486d4a30 935 }
nixnax 29:30de79d658f6 936 }
nixnax 9:0992486d4a30 937
nixnax 50:ad4e7c3c88e5 938 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 939 {
nixnax 85:53e57ff1cf05 940 while(1) {
nixnax 93:9675adc36882 941 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 942 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 943 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 944 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 945 if (rx==FRAME_7E) {
nixnax 81:9ede60e9a2c8 946 if (ppp.hdlc.frameFound == 0) { // we are still waiting for a frame start
nixnax 81:9ede60e9a2c8 947 ppp.hdlc.frameFound = 1; // we found our first frame start
nixnax 81:9ede60e9a2c8 948 ppp.hdlc.frameStartIndex=ppp.rx.tail; // remember where the frame character is in the buffer
nixnax 51:a86d56844324 949 } else {
nixnax 81:9ede60e9a2c8 950 // we have previously found a frame start
nixnax 81:9ede60e9a2c8 951 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 81:9ede60e9a2c8 952 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 93:9675adc36882 953 ppp.rx.rtail = ppp.rx.tail;
nixnax 81:9ede60e9a2c8 954 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 81:9ede60e9a2c8 955 break;
nixnax 50:ad4e7c3c88e5 956 }
nixnax 50:ad4e7c3c88e5 957 }
nixnax 50:ad4e7c3c88e5 958 }
nixnax 85:53e57ff1cf05 959 }
nixnax 50:ad4e7c3c88e5 960 }
nixnax 50:ad4e7c3c88e5 961
nixnax 29:30de79d658f6 962 void scanForConnectString()
nixnax 29:30de79d658f6 963 {
nixnax 81:9ede60e9a2c8 964 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 965 fillbuf();
nixnax 81:9ede60e9a2c8 966 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 81:9ede60e9a2c8 967 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENTCLIENT" );
nixnax 81:9ede60e9a2c8 968 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 969 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 970 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 971 if (found1 != NULL) {
nixnax 81:9ede60e9a2c8 972 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 81:9ede60e9a2c8 973 pc.puts("CLIENTSERVER");
nixnax 81:9ede60e9a2c8 974 if (v0) debug("Found connect string \"CLIENTCLIENT\"\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 103:4f5512dd11cf 999 }