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@96:e14f42ecff66, 2017-07-29 (annotated)

Committer:
nixnax
Date:
Sat Jul 29 00:31:13 2017 +0000
Revision:
96:e14f42ecff66
Parent:
95:40af49390daf
Child:
97:bdf885e146dc
TCP Window size of 3*256

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 0:2cf4880c312a 4
nixnax 41:e58a5a09f411 5 // Also receives UDP packets and responds to ping (ICMP Echo requests)
nixnax 4:a469050d5b80 6
nixnax 93:9675adc36882 7 // 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 8
nixnax 41:e58a5a09f411 9 // Notes and Instructions
nixnax 41:e58a5a09f411 10 // http://bit.ly/PPP-Blinky-Instructions
nixnax 0:2cf4880c312a 11
nixnax 41:e58a5a09f411 12 // Handy reading material
nixnax 6:fba4c2e817b8 13 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 9:0992486d4a30 14 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 39:b90183d35f1e 15 // http://bit.ly/dialup777error - how to solve Dial Up Error 777 in Windows 7/8/10
nixnax 41:e58a5a09f411 16 // http://atari.kensclassics.org/wcomlog.htm
nixnax 6:fba4c2e817b8 17
nixnax 29:30de79d658f6 18 // Handy tools
nixnax 44:d0c61ae49ea5 19 // https://ttssh2.osdn.jp/index.html.en - Tera Term, a good terminal program to monitor the debug output from the second serial port with!
nixnax 92:cb962b365cce 20 // https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets -
nixnax 29:30de79d658f6 21 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 95:40af49390daf 22 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE), then custom relected-in=1, reflected-out=1
nixnax 29:30de79d658f6 23 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 41:e58a5a09f411 24 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 91:5141ae9fba53 25 // Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax 41:e58a5a09f411 26
nixnax 92:cb962b365cce 27 // Connecting PPP-Blinky to Linux
nixnax 93:9675adc36882 28 // PPP-Blinky can be made to talk to Linux - tested on Fedora - the following command, which uses pppd, works:
nixnax 93:9675adc36882 29 // pppd /dev/ttyACM0 115200 debug dump local passive noccp novj nodetach nocrtscts 172.10.10.1:172.10.10.2
nixnax 92:cb962b365cce 30 // in the above command 172.10.10.1 is the adapter IP, and 172.10.10.2 is the IP of PPP-Blinky.
nixnax 93:9675adc36882 31 // See also https://en.wikipedia.org/wiki/Point-to-Point_Protocol_daemon
nixnax 93:9675adc36882 32
nixnax 93:9675adc36882 33 // Ok, enough talking, time to check out some code!!
nixnax 92:cb962b365cce 34
nixnax 81:9ede60e9a2c8 35 #include "mbed.h"
nixnax 66:f005b9fdf4d1 36
nixnax 93:9675adc36882 37 // The #define below enables/disables a second (OPTIONAL) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 38 // Change to SERIAL_PORT_MONITOR_YES to enable diagnostics messages. You need to wire a second serial port to your mbed hardware to monitor this.
nixnax 94:8ee3eec2a2bb 39 #define SERIAL_PORT_MONITOR_NO /* change to SERIAL_PORT_MONITOR_YES for debug messages */
nixnax 0:2cf4880c312a 40
nixnax 41:e58a5a09f411 41 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 42
nixnax 93:9675adc36882 43 // here we define the OPTIONAL, second debug serial port for the various target boards
nixnax 93:9675adc36882 44 // 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 45 #if defined(TARGET_LPC1768)
nixnax 85:53e57ff1cf05 46 Serial xx(p9, p10); // Second serial port on LPC1768 - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax 88:b4a71242837c 47 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE)
nixnax 85:53e57ff1cf05 48 Serial xx(PC_10, PC_11); // Second serial port on NUCLEO boards - not required to run, if you get compile error here, change #define SERIAL_PORT_MONITOR_YES to #define SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 49 #else
nixnax 85:53e57ff1cf05 50 #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 51 #endif
nixnax 85:53e57ff1cf05 52
nixnax 93:9675adc36882 53 #define debug(x...) xx.printf (x)
nixnax 85:53e57ff1cf05 54
nixnax 41:e58a5a09f411 55 #else
nixnax 42:4de44be70bfd 56 #define debug(x...) {}
nixnax 41:e58a5a09f411 57 #endif
nixnax 41:e58a5a09f411 58
nixnax 93:9675adc36882 59 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 90:55e0f243a7ce 60 #define v0 0
nixnax 93:9675adc36882 61 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 62 #define v1 0
nixnax 93:9675adc36882 63 // verbosity flag used in debug printouts - change to 1 to see more debug info. Lots of interesting info.
nixnax 77:abf92baebb42 64 #define v2 0
nixnax 29:30de79d658f6 65
nixnax 93:9675adc36882 66 // this is the webpage we serve when we get an HTTP request to root (/)
nixnax 93:9675adc36882 67 // keep size under ~900 bytes to fit into a single PPP packet
nixnax 93:9675adc36882 68 const static char rootWebPage[] = "\
nixnax 66:f005b9fdf4d1 69 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 70 <html>\
nixnax 66:f005b9fdf4d1 71 <head>\
nixnax 66:f005b9fdf4d1 72 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 73 <script>\
nixnax 66:f005b9fdf4d1 74 window.onload=function(){\
nixnax 66:f005b9fdf4d1 75 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 76 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 77 </script>\
nixnax 66:f005b9fdf4d1 78 </head>\
nixnax 66:f005b9fdf4d1 79 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 80 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 81 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 82 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 83 </body>\
nixnax 69:23f560087c16 84 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 85
nixnax 73:2f56ec87dbe9 86 // The serial port on your mbed hardware. Your PC should be configured to view this port as a standard dial-up networking modem.
nixnax 73:2f56ec87dbe9 87 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 88 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 89 // See instructions at the top.
nixnax 73:2f56ec87dbe9 90 // On a typical mbed hardware platform this serial port is a USB virtual com port (VCP) and the USB serial driver is supplied by the board vendor.
nixnax 73:2f56ec87dbe9 91 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 92
nixnax 29:30de79d658f6 93 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 94
nixnax 66:f005b9fdf4d1 95 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 96 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 97
nixnax 29:30de79d658f6 98 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 99 struct pppType {
nixnax 38:ab582987926e 100 int online; // we hunt for a PPP connection if this is zero
nixnax 87:9f5ac1fabd95 101 unsigned int ident; // our IP ident value
nixnax 38:ab582987926e 102 unsigned int seq; // our TCP sequence number
nixnax 38:ab582987926e 103 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 104 int ledState; // state of LED1
nixnax 87:9f5ac1fabd95 105 int httpFrameCount;
nixnax 4:a469050d5b80 106 struct {
nixnax 81:9ede60e9a2c8 107 #define RXBUFLEN (1<<14)
nixnax 93:9675adc36882 108 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 8192 bytes)
nixnax 85:53e57ff1cf05 109 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 93:9675adc36882 110 int head;
nixnax 93:9675adc36882 111 int tail;
nixnax 95:40af49390daf 112 int rtail;
nixnax 93:9675adc36882 113 int buflevel;
nixnax 38:ab582987926e 114 } rx; // serial port objects
nixnax 4:a469050d5b80 115 struct {
nixnax 38:ab582987926e 116 int len; // number of bytes in buffer
nixnax 38:ab582987926e 117 int crc; // PPP CRC (frame check)
nixnax 77:abf92baebb42 118 #define TCP_max_size 3300
nixnax 77:abf92baebb42 119 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 120 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 121 struct {
nixnax 50:ad4e7c3c88e5 122 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 123 int frameEndIndex; // frame end marker
nixnax 81:9ede60e9a2c8 124 int frameFound; // we have found at least one start of frame already
nixnax 50:ad4e7c3c88e5 125 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 126 };
nixnax 31:e000c1b9c565 127
nixnax 29:30de79d658f6 128 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 129
nixnax 93:9675adc36882 130 // Initialize our global structure, clear the buffer, etc.
nixnax 29:30de79d658f6 131 void pppInitStruct()
nixnax 29:30de79d658f6 132 {
nixnax 81:9ede60e9a2c8 133 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 134 ppp.online=0;
nixnax 29:30de79d658f6 135 ppp.rx.tail=0;
nixnax 93:9675adc36882 136 ppp.rx.rtail=0;
nixnax 29:30de79d658f6 137 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 138 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 139 ppp.pkt.len=0;
nixnax 83:cdcb81d1910f 140 ppp.ident=1000;
nixnax 29:30de79d658f6 141 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 142 ppp.hdlc.frameFound=0;
nixnax 81:9ede60e9a2c8 143 ppp.hdlc.frameStartIndex=0;
nixnax 87:9f5ac1fabd95 144 ppp.httpFrameCount=0;
nixnax 29:30de79d658f6 145 }
nixnax 26:11f4eb2663a7 146
nixnax 43:aa57db08995d 147 void led1Toggle()
nixnax 43:aa57db08995d 148 {
nixnax 43:aa57db08995d 149 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 93:9675adc36882 150 led1 = ppp.ledState; // toggle led
nixnax 43:aa57db08995d 151 }
nixnax 43:aa57db08995d 152
nixnax 29:30de79d658f6 153 void crcReset()
nixnax 29:30de79d658f6 154 {
nixnax 29:30de79d658f6 155 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 156 }
nixnax 4:a469050d5b80 157
nixnax 29:30de79d658f6 158 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 159 {
nixnax 29:30de79d658f6 160 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 161 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 162 x>>=1;
nixnax 29:30de79d658f6 163 }
nixnax 29:30de79d658f6 164 }
nixnax 29:30de79d658f6 165
nixnax 29:30de79d658f6 166 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 167 {
nixnax 31:e000c1b9c565 168 crcReset();
nixnax 31:e000c1b9c565 169 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 170 return ppp.crc;
nixnax 29:30de79d658f6 171 }
nixnax 0:2cf4880c312a 172
nixnax 85:53e57ff1cf05 173
nixnax 85:53e57ff1cf05 174 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 175 void fillbuf()
nixnax 0:2cf4880c312a 176 {
nixnax 85:53e57ff1cf05 177 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 178 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 93:9675adc36882 179 if ( hd == ppp.rx.rtail ) {
nixnax 85:53e57ff1cf05 180 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 181 return;
nixnax 83:cdcb81d1910f 182 }
nixnax 17:4918c893d802 183 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 184 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 185 ppp.rx.buflevel++;
nixnax 15:b0154c910143 186 }
nixnax 0:2cf4880c312a 187 }
nixnax 0:2cf4880c312a 188
nixnax 85:53e57ff1cf05 189 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 190 {
nixnax 43:aa57db08995d 191 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 192 return emptyStatus;
nixnax 0:2cf4880c312a 193 }
nixnax 0:2cf4880c312a 194
nixnax 85:53e57ff1cf05 195 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 196 {
nixnax 63:9253b0e1b7d8 197 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 198 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 199 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 200 return x;
nixnax 0:2cf4880c312a 201 }
nixnax 0:2cf4880c312a 202
nixnax 95:40af49390daf 203 // Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 95:40af49390daf 204 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 95:40af49390daf 205 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 95:40af49390daf 206 void dumpPPPFrame()
nixnax 95:40af49390daf 207 {
nixnax 95:40af49390daf 208 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 95:40af49390daf 209 debug(" CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 95:40af49390daf 210 }
nixnax 95:40af49390daf 211
nixnax 50:ad4e7c3c88e5 212 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 213 {
nixnax 38:ab582987926e 214 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 215 if(start==end) {
nixnax 29:30de79d658f6 216 return;
nixnax 29:30de79d658f6 217 }
nixnax 9:0992486d4a30 218 crcReset();
nixnax 9:0992486d4a30 219 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 220 ppp.pkt.len=0;
nixnax 9:0992486d4a30 221 int unstuff=0;
nixnax 17:4918c893d802 222 int idx = start;
nixnax 17:4918c893d802 223 while(1) {
nixnax 9:0992486d4a30 224 if (unstuff==0) {
nixnax 72:ad3d12753acf 225 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 226 else {
nixnax 72:ad3d12753acf 227 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 228 ppp.pkt.len++;
nixnax 29:30de79d658f6 229 dest++;
nixnax 72:ad3d12753acf 230 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 231 }
nixnax 66:f005b9fdf4d1 232 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 233 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 234 ppp.pkt.len++;
nixnax 29:30de79d658f6 235 dest++;
nixnax 72:ad3d12753acf 236 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 237 unstuff=0;
nixnax 9:0992486d4a30 238 }
nixnax 81:9ede60e9a2c8 239 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 240 if (idx == end) break;
nixnax 9:0992486d4a30 241 }
nixnax 29:30de79d658f6 242 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 243 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 244 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 245 determinePacketType();
nixnax 90:55e0f243a7ce 246 } else {
nixnax 95:40af49390daf 247 if (0) { // don't normally report FCS because windows early-terminates packets, and early-terminated packets all have FCS errors.
nixnax 95:40af49390daf 248 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 249 }
nixnax 9:0992486d4a30 250 }
nixnax 9:0992486d4a30 251 }
nixnax 9:0992486d4a30 252
nixnax 29:30de79d658f6 253 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 254 {
nixnax 29:30de79d658f6 255 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 256 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 257 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 258 } else {
nixnax 29:30de79d658f6 259 pc.putc(ch);
nixnax 29:30de79d658f6 260 }
nixnax 11:f58998c24f0b 261 }
nixnax 9:0992486d4a30 262
nixnax 93:9675adc36882 263 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 264 {
nixnax 17:4918c893d802 265 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 266 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 267 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 268 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 95:40af49390daf 269 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 270 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 95:40af49390daf 271
nixnax 93:9675adc36882 272 if((i&0x7f)==0) fillbuf(); // handle received characters very every 128 sent
nixnax 93:9675adc36882 273 }
nixnax 16:cb0b80c24ba2 274 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 275 }
nixnax 9:0992486d4a30 276
nixnax 93:9675adc36882 277 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 278 {
nixnax 93:9675adc36882 279 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 280 ppp.pkt.buf[4]=2; // change code to ack
nixnax 93:9675adc36882 281 send_pppFrame(); // simply acknowledge everything they ask for
nixnax 93:9675adc36882 282 debug("Our IPCP Ask\n");
nixnax 92:cb962b365cce 283 // send our own request now
nixnax 92:cb962b365cce 284 ppp.pkt.buf[4]=1; // change code to request
nixnax 92:cb962b365cce 285 ppp.pkt.buf[5]++; // increment sequence number
nixnax 92:cb962b365cce 286 ppp.pkt.buf[7]=4; // no options requested
nixnax 93:9675adc36882 287 send_pppFrame(); // this is our request
nixnax 92:cb962b365cce 288 return;
nixnax 9:0992486d4a30 289 }
nixnax 9:0992486d4a30 290
nixnax 93:9675adc36882 291 void ipcpAckHandler()
nixnax 29:30de79d658f6 292 {
nixnax 93:9675adc36882 293 debug("Their IPCP Grant\n");
nixnax 29:30de79d658f6 294 }
nixnax 9:0992486d4a30 295
nixnax 93:9675adc36882 296 void ipcpNackHandler()
nixnax 29:30de79d658f6 297 {
nixnax 93:9675adc36882 298 debug("Their IPCP Nack\n");
nixnax 29:30de79d658f6 299 }
nixnax 9:0992486d4a30 300
nixnax 93:9675adc36882 301 void ipcpDefaultHandler()
nixnax 29:30de79d658f6 302 {
nixnax 93:9675adc36882 303 debug("Their IPCP Other\n");
nixnax 29:30de79d658f6 304 }
nixnax 29:30de79d658f6 305
nixnax 29:30de79d658f6 306 void IPCPframe()
nixnax 29:30de79d658f6 307 {
nixnax 9:0992486d4a30 308 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 309 switch (code) {
nixnax 29:30de79d658f6 310 case 1:
nixnax 93:9675adc36882 311 ipcpConfigRequestHandler();
nixnax 29:30de79d658f6 312 break;
nixnax 29:30de79d658f6 313 case 2:
nixnax 93:9675adc36882 314 ipcpAckHandler();
nixnax 29:30de79d658f6 315 break;
nixnax 29:30de79d658f6 316 case 3:
nixnax 93:9675adc36882 317 ipcpNackHandler();
nixnax 29:30de79d658f6 318 break;
nixnax 29:30de79d658f6 319 default:
nixnax 93:9675adc36882 320 ipcpDefaultHandler();
nixnax 9:0992486d4a30 321 }
nixnax 29:30de79d658f6 322 }
nixnax 9:0992486d4a30 323
nixnax 29:30de79d658f6 324 void UDPpacket()
nixnax 29:30de79d658f6 325 {
nixnax 12:db0dc91f0231 326 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 327 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 328 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 329 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 330 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 331 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 332 #endif
nixnax 12:db0dc91f0231 333 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 334 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 335 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 336 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 337 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 338 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 339 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 340 #endif
nixnax 29:30de79d658f6 341 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 342 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 343 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 344 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 345 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 346 int printSize = udpLength;
nixnax 29:30de79d658f6 347 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 348 if (v1) {
nixnax 29:30de79d658f6 349 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 350 char ch = udpInf[i];
nixnax 29:30de79d658f6 351 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 352 debug("%c", ch);
nixnax 29:30de79d658f6 353 } else {
nixnax 64:677b9713a120 354 debug("_");
nixnax 29:30de79d658f6 355 }
nixnax 29:30de79d658f6 356 }
nixnax 29:30de79d658f6 357 }
nixnax 83:cdcb81d1910f 358 if (v0) debug("\n");
nixnax 12:db0dc91f0231 359 }
nixnax 11:f58998c24f0b 360
nixnax 76:00e208cceb8b 361 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 362 {
nixnax 77:abf92baebb42 363
nixnax 75:0d513869231f 364 unsigned int sum=0;
nixnax 76:00e208cceb8b 365 unsigned char placeHolder;
nixnax 29:30de79d658f6 366 if (len&1) {
nixnax 76:00e208cceb8b 367 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 368 ptr[len]=0;
nixnax 29:30de79d658f6 369 }
nixnax 29:30de79d658f6 370 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 371 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 372 ptr++;
nixnax 76:00e208cceb8b 373 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 374 ptr++;
nixnax 76:00e208cceb8b 375 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 376 sum = sum + val;
nixnax 11:f58998c24f0b 377 }
nixnax 29:30de79d658f6 378 if (len&1) {
nixnax 76:00e208cceb8b 379 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 380 }
nixnax 76:00e208cceb8b 381 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 382 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 383 return ~sum;
nixnax 29:30de79d658f6 384 }
nixnax 11:f58998c24f0b 385
nixnax 29:30de79d658f6 386 void headerCheckSum()
nixnax 29:30de79d658f6 387 {
nixnax 11:f58998c24f0b 388 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 389 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 390 int sum=0;
nixnax 11:f58998c24f0b 391
nixnax 29:30de79d658f6 392 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 393 int hi = *ptr;
nixnax 29:30de79d658f6 394 ptr++;
nixnax 29:30de79d658f6 395 int lo = *ptr;
nixnax 29:30de79d658f6 396 ptr++;
nixnax 11:f58998c24f0b 397 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 398 sum = sum + val;
nixnax 11:f58998c24f0b 399 }
nixnax 11:f58998c24f0b 400 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 401 sum = ~sum;
nixnax 11:f58998c24f0b 402 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 403 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 404 }
nixnax 9:0992486d4a30 405
nixnax 29:30de79d658f6 406 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 407 {
nixnax 12:db0dc91f0231 408 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 409 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 410 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 411 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 412 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 413 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 414 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 415 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 416 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 417 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 418 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 419 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 420 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 421 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 422 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 423 #endif
nixnax 81:9ede60e9a2c8 424 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 425 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 426 char src[4];
nixnax 29:30de79d658f6 427 char dst[4];
nixnax 12:db0dc91f0231 428 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 429 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 430 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 431 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 432 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 433 chkSum[0]=0;
nixnax 29:30de79d658f6 434 chkSum[1]=0;
nixnax 12:db0dc91f0231 435 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 436 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 437 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 438 icmpSum[0]=0;
nixnax 29:30de79d658f6 439 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 440 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 441 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 442 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 443 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 444
nixnax 16:cb0b80c24ba2 445 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 446 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 447 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 448 if (v0) {
nixnax 29:30de79d658f6 449 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 450 char ch = icmpData[i];
nixnax 29:30de79d658f6 451 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 452 debug("%c",ch);
nixnax 29:30de79d658f6 453 } else {
nixnax 64:677b9713a120 454 debug("_");
nixnax 29:30de79d658f6 455 }
nixnax 29:30de79d658f6 456 }
nixnax 64:677b9713a120 457 debug("\n");
nixnax 29:30de79d658f6 458 }
nixnax 93:9675adc36882 459 send_pppFrame(); // reply to the ping
nixnax 29:30de79d658f6 460
nixnax 12:db0dc91f0231 461 } else {
nixnax 29:30de79d658f6 462 if (v0) {
nixnax 42:4de44be70bfd 463 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 464 }
nixnax 11:f58998c24f0b 465 }
nixnax 11:f58998c24f0b 466 }
nixnax 11:f58998c24f0b 467
nixnax 29:30de79d658f6 468 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 469 {
nixnax 29:30de79d658f6 470 if (v0) {
nixnax 42:4de44be70bfd 471 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 472 }
nixnax 29:30de79d658f6 473 }
nixnax 11:f58998c24f0b 474
nixnax 29:30de79d658f6 475 void dumpHeaderIP ()
nixnax 29:30de79d658f6 476 {
nixnax 95:40af49390daf 477 if (v0) {
nixnax 95:40af49390daf 478 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 479 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 480 char * version = ipPkt; // top 4 bits
nixnax 95:40af49390daf 481 char * ihl = ipPkt; // bottom 4 bits
nixnax 95:40af49390daf 482 char * dscp = ipPkt+1; // top 6 bits
nixnax 95:40af49390daf 483 char * ecn = ipPkt+1; // lower 2 bits
nixnax 95:40af49390daf 484 char * pktLen = ipPkt+2; // 2 bytes
nixnax 95:40af49390daf 485 char * ident = ipPkt+4; // 2 bytes
nixnax 95:40af49390daf 486 char * flags = ipPkt+6; // 2 bits
nixnax 95:40af49390daf 487 char * ttl = ipPkt+8; // 1 byte
nixnax 95:40af49390daf 488 char * protocol = ipPkt+9; // 1 byte
nixnax 95:40af49390daf 489 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 490 #endif
nixnax 95:40af49390daf 491 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 95:40af49390daf 492 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 493
nixnax 55:43faae812be3 494 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 495 int versionIP = (version[0]>>4)&0xf;
nixnax 95:40af49390daf 496 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 95:40af49390daf 497 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 95:40af49390daf 498 int ecnIP = ecn[0]&3;
nixnax 95:40af49390daf 499 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 95:40af49390daf 500 int identIP = (ident[0]<<8)|ident[1];
nixnax 95:40af49390daf 501 int flagsIP = flags[0]>>14&3;
nixnax 95:40af49390daf 502 int ttlIP = ttl[0];
nixnax 95:40af49390daf 503 int protocolIP = protocol[0];
nixnax 95:40af49390daf 504 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 505 #endif
nixnax 55:43faae812be3 506
nixnax 95:40af49390daf 507 char srcIP [16];
nixnax 95:40af49390daf 508 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 95:40af49390daf 509 char dstIP [16];
nixnax 95:40af49390daf 510 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 95:40af49390daf 511 debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 95:40af49390daf 512 debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 95:40af49390daf 513 }
nixnax 29:30de79d658f6 514 }
nixnax 26:11f4eb2663a7 515
nixnax 29:30de79d658f6 516 void dumpHeaderTCP()
nixnax 29:30de79d658f6 517 {
nixnax 83:cdcb81d1910f 518 if( v0 ) {
nixnax 81:9ede60e9a2c8 519
nixnax 81:9ede60e9a2c8 520 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 521 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 522 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 523 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 524 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 525 #endif
nixnax 81:9ede60e9a2c8 526 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 527 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 528 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 529 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 530 #endif
nixnax 81:9ede60e9a2c8 531 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 532
nixnax 81:9ede60e9a2c8 533 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 534 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 535 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 536
nixnax 81:9ede60e9a2c8 537 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 538 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 539 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 540 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 541 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 542 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 543 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 544 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 545 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 546 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 547 }
nixnax 29:30de79d658f6 548 }
nixnax 29:30de79d658f6 549
nixnax 68:0b74763ae67f 550 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 551 {
nixnax 67:a63e3486bcda 552 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 553 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 554 int contentLengthStart; // index where HTML starts
nixnax 93:9675adc36882 555 int xFetch, httpGetRoot; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 556
nixnax 87:9f5ac1fabd95 557 ppp.httpFrameCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 558
nixnax 93:9675adc36882 559 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.1", 14); // found GET /
nixnax 89:2c8dd0c2a426 560 xFetch = strncmp(dataStart, "GET /x HTTP/1.1", 15); // found GET /x
nixnax 93:9675adc36882 561 if( (httpGetRoot==0) || (xFetch==0) ) {
nixnax 89:2c8dd0c2a426 562 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 563 } else {
nixnax 89:2c8dd0c2a426 564 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 565 }
nixnax 83:cdcb81d1910f 566 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 567 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 568 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 569 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 570 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 571 nHeader=n; // size of HTTP header
nixnax 93:9675adc36882 572 if( httpGetRoot == 0 ) {
nixnax 83:cdcb81d1910f 573 // this is where we insert our web page into the buffer
nixnax 93:9675adc36882 574 //n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 93:9675adc36882 575 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 93:9675adc36882 576 n = n + sizeof(rootWebPage);
nixnax 85:53e57ff1cf05 577 } else {
nixnax 89:2c8dd0c2a426 578 if (xFetch == 0) {
nixnax 89:2c8dd0c2a426 579
nixnax 89:2c8dd0c2a426 580 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 89:2c8dd0c2a426 581 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 89:2c8dd0c2a426 582 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 89:2c8dd0c2a426 583 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed-ppp-blinky</title>"); // html title (W3C.org required element)
nixnax 94:8ee3eec2a2bb 584 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.httpFrameCount); // body = the http frame count
nixnax 89:2c8dd0c2a426 585 #else
nixnax 95:40af49390daf 586 n=n+sprintf(n+dataStart,"%d",ppp.httpFrameCount); // not valid html but fast, most browsers and curl are ok with it
nixnax 89:2c8dd0c2a426 587 #endif
nixnax 89:2c8dd0c2a426 588
nixnax 89:2c8dd0c2a426 589 } else {
nixnax 89:2c8dd0c2a426 590 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 89:2c8dd0c2a426 591 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky-mbed</title>"); // html title (required element)
nixnax 89:2c8dd0c2a426 592 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 89:2c8dd0c2a426 593 }
nixnax 83:cdcb81d1910f 594 }
nixnax 87:9f5ac1fabd95 595 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 596 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 597
nixnax 83:cdcb81d1910f 598 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 599 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 600 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 601 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 602
nixnax 77:abf92baebb42 603 if (v2) {
nixnax 77:abf92baebb42 604 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 605 }
nixnax 67:a63e3486bcda 606 return n; // total byte size of our response
nixnax 67:a63e3486bcda 607 }
nixnax 67:a63e3486bcda 608
nixnax 67:a63e3486bcda 609
nixnax 29:30de79d658f6 610 void tcpHandler()
nixnax 29:30de79d658f6 611 {
nixnax 87:9f5ac1fabd95 612 // IP header
nixnax 87:9f5ac1fabd95 613
nixnax 26:11f4eb2663a7 614 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 615 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 616 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 617 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 618 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 619 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 620 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 621 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 622 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 623 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 624
nixnax 87:9f5ac1fabd95 625 // TCP header
nixnax 87:9f5ac1fabd95 626
nixnax 87:9f5ac1fabd95 627 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 628 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 629 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 630 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 631 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 632 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 633 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 634 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 635 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 636
nixnax 26:11f4eb2663a7 637 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 638 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 639 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 640
nixnax 87:9f5ac1fabd95 641 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 642 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 643 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 644
nixnax 85:53e57ff1cf05 645 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 646 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 647
nixnax 85:53e57ff1cf05 648 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 649 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 650
nixnax 28:1aa629be05e7 651
nixnax 29:30de79d658f6 652 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 653 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 654 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 655 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 656 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 657
nixnax 87:9f5ac1fabd95 658 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 659 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 660
nixnax 87:9f5ac1fabd95 661 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 662 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 663 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 664 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 665 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 666 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 667
nixnax 35:e7068df4d971 668 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 669 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 670 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 671
nixnax 96:e14f42ecff66 672 windowsizetcp[0]=3; // tco window size = 3*256=768
nixnax 96:e14f42ecff66 673 windowsizetcp[1]=0; // tcp windows size low byte
nixnax 38:ab582987926e 674
nixnax 93:9675adc36882 675 int doFin = 0; // flag to see if we have to send an extra FIN message to shut down the link
nixnax 93:9675adc36882 676
nixnax 69:23f560087c16 677 // A sparse TCP flag interpreter that implements simple TCP connections from a single source
nixnax 69:23f560087c16 678 // Clients are allowed ONE push packet, after which the link is closed with a FIN flag in the ACK packet
nixnax 69:23f560087c16 679 // This strategy allows web browsers, netcat and curl to work ok while keeping the state machine simple
nixnax 77:abf92baebb42 680
nixnax 69:23f560087c16 681 switch ( flagsTCP ) {
nixnax 69:23f560087c16 682 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 683 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 684 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 685 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 686 break;
nixnax 77:abf92baebb42 687 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 93:9675adc36882 688 flagsOut = TCP_FLAG_ACK ; //| TCP_FLAG_FIN; // for every push we answer once AND close the link
nixnax 87:9f5ac1fabd95 689 if ( strncmp(tcpDataIn, "GET ", 4) == 0) { // check for an http GET command
nixnax 87:9f5ac1fabd95 690 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 69:23f560087c16 691 }
nixnax 69:23f560087c16 692 break;
nixnax 77:abf92baebb42 693 case TCP_FLAG_FIN:
nixnax 69:23f560087c16 694 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 93:9675adc36882 695 case TCP_FLAG_RST:
nixnax 93:9675adc36882 696 doFin = 1; // they want to tear down the link, so we must send a FIN packet also
nixnax 85:53e57ff1cf05 697 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 698 break;
nixnax 77:abf92baebb42 699 default:
nixnax 69:23f560087c16 700 return; // ignore remaining packets
nixnax 93:9675adc36882 701 } // switch
nixnax 77:abf92baebb42 702
nixnax 69:23f560087c16 703 // The TCP flag handling is now done
nixnax 95:40af49390daf 704
nixnax 93:9675adc36882 705 // first we swap sourc and destination TCP addresses and insert the new ack and seq numbers
nixnax 95:40af49390daf 706
nixnax 65:23b17c43aa0f 707 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 708 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 709 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 710 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 711
nixnax 60:2b770949c911 712 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 713 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 714 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 95:40af49390daf 715
nixnax 93:9675adc36882 716 sendTCP:
nixnax 83:cdcb81d1910f 717
nixnax 85:53e57ff1cf05 718 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 719 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 720 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 721 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 722
nixnax 85:53e57ff1cf05 723 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 724 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 725 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 726 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 727
nixnax 93:9675adc36882 728 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 729
nixnax 93:9675adc36882 730 // increment the ip ident number
nixnax 38:ab582987926e 731
nixnax 93:9675adc36882 732 ppp.ident++; // get next ident number for our packet
nixnax 93:9675adc36882 733 ident[0] = ppp.ident>>8;
nixnax 93:9675adc36882 734 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 735
nixnax 93:9675adc36882 736 // Now we recalculate all the header sizes, and do the IP and TCP checksums
nixnax 38:ab582987926e 737 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 738 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 739 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 740 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 741 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 742
nixnax 38:ab582987926e 743 // the header is all set up, now do the IP and TCP checksums
nixnax 36:2a9b457f8276 744
nixnax 61:b3c1a04efd0a 745 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 746 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 747 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 748
nixnax 64:677b9713a120 749 // 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 750 // 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 751
nixnax 87:9f5ac1fabd95 752 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 753 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 754 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 755 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 756 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 757 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 758 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 759
nixnax 61:b3c1a04efd0a 760 // pseudo-header built, now we can calculate TCP checksum
nixnax 63:9253b0e1b7d8 761
nixnax 29:30de79d658f6 762 checksumtcp[0]=0;
nixnax 29:30de79d658f6 763 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 764 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 765 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 766 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 767 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 95:40af49390daf 768
nixnax 93:9675adc36882 769 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 60:2b770949c911 770
nixnax 93:9675adc36882 771 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 772 doFin=0;
nixnax 93:9675adc36882 773 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // tell them we are also finished
nixnax 93:9675adc36882 774 goto sendTCP; // send our final packet for this conversation.
nixnax 93:9675adc36882 775 }
nixnax 95:40af49390daf 776
nixnax 83:cdcb81d1910f 777 dumpHeaderIP();
nixnax 95:40af49390daf 778 dumpHeaderTCP();
nixnax 93:9675adc36882 779
nixnax 29:30de79d658f6 780 }
nixnax 26:11f4eb2663a7 781
nixnax 29:30de79d658f6 782 void dumpDataTCP()
nixnax 29:30de79d658f6 783 {
nixnax 26:11f4eb2663a7 784 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 785 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 786 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 787 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 788 if (v1) {
nixnax 42:4de44be70bfd 789 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 790 }
nixnax 29:30de79d658f6 791 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 792 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 793 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 794 }
nixnax 29:30de79d658f6 795 }
nixnax 26:11f4eb2663a7 796
nixnax 29:30de79d658f6 797 void TCPpacket()
nixnax 29:30de79d658f6 798 {
nixnax 83:cdcb81d1910f 799 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 800 dumpHeaderTCP();
nixnax 77:abf92baebb42 801 if (v2) {
nixnax 77:abf92baebb42 802 dumpDataTCP();
nixnax 77:abf92baebb42 803 }
nixnax 26:11f4eb2663a7 804 tcpHandler();
nixnax 11:f58998c24f0b 805 }
nixnax 11:f58998c24f0b 806
nixnax 29:30de79d658f6 807 void otherProtocol()
nixnax 29:30de79d658f6 808 {
nixnax 64:677b9713a120 809 debug("Other IP protocol");
nixnax 29:30de79d658f6 810 }
nixnax 26:11f4eb2663a7 811
nixnax 29:30de79d658f6 812 void IPframe()
nixnax 29:30de79d658f6 813 {
nixnax 10:74f8233f72c0 814 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 815 switch (protocol) {
nixnax 29:30de79d658f6 816 case 1:
nixnax 29:30de79d658f6 817 ICMPpacket();
nixnax 29:30de79d658f6 818 break;
nixnax 29:30de79d658f6 819 case 2:
nixnax 29:30de79d658f6 820 IGMPpacket();
nixnax 29:30de79d658f6 821 break;
nixnax 29:30de79d658f6 822 case 17:
nixnax 29:30de79d658f6 823 UDPpacket();
nixnax 29:30de79d658f6 824 break;
nixnax 29:30de79d658f6 825 case 6:
nixnax 29:30de79d658f6 826 TCPpacket();
nixnax 29:30de79d658f6 827 break;
nixnax 29:30de79d658f6 828 default:
nixnax 29:30de79d658f6 829 otherProtocol();
nixnax 29:30de79d658f6 830 }
nixnax 29:30de79d658f6 831 }
nixnax 9:0992486d4a30 832
nixnax 29:30de79d658f6 833 void LCPconfReq()
nixnax 29:30de79d658f6 834 {
nixnax 64:677b9713a120 835 debug("LCP Config ");
nixnax 9:0992486d4a30 836 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 837 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 838 debug("Reject\n");
nixnax 93:9675adc36882 839 send_pppFrame();
nixnax 9:0992486d4a30 840 } else {
nixnax 9:0992486d4a30 841 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 842 debug("Ack\n");
nixnax 93:9675adc36882 843 send_pppFrame();
nixnax 64:677b9713a120 844 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 845 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 846 send_pppFrame();
nixnax 9:0992486d4a30 847 }
nixnax 9:0992486d4a30 848 }
nixnax 9:0992486d4a30 849
nixnax 29:30de79d658f6 850 void LCPconfAck()
nixnax 29:30de79d658f6 851 {
nixnax 64:677b9713a120 852 debug("LCP Ack\n");
nixnax 29:30de79d658f6 853 }
nixnax 9:0992486d4a30 854
nixnax 29:30de79d658f6 855 void LCPend()
nixnax 29:30de79d658f6 856 {
nixnax 29:30de79d658f6 857 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 858 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 859 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 860 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 861 debug("LCP End\n");
nixnax 9:0992486d4a30 862 }
nixnax 9:0992486d4a30 863
nixnax 29:30de79d658f6 864 void LCPother()
nixnax 29:30de79d658f6 865 {
nixnax 64:677b9713a120 866 debug("LCP Other\n");
nixnax 95:40af49390daf 867 dumpPPPFrame();
nixnax 29:30de79d658f6 868 }
nixnax 29:30de79d658f6 869
nixnax 29:30de79d658f6 870 void LCPframe()
nixnax 29:30de79d658f6 871 {
nixnax 29:30de79d658f6 872 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 873 switch (code) {
nixnax 29:30de79d658f6 874 case 1:
nixnax 29:30de79d658f6 875 LCPconfReq();
nixnax 29:30de79d658f6 876 break; // config request
nixnax 29:30de79d658f6 877 case 2:
nixnax 29:30de79d658f6 878 LCPconfAck();
nixnax 29:30de79d658f6 879 break; // config ack
nixnax 29:30de79d658f6 880 case 5:
nixnax 29:30de79d658f6 881 LCPend();
nixnax 29:30de79d658f6 882 break; // end connection
nixnax 29:30de79d658f6 883 default:
nixnax 29:30de79d658f6 884 LCPother();
nixnax 29:30de79d658f6 885 }
nixnax 9:0992486d4a30 886 }
nixnax 9:0992486d4a30 887
nixnax 29:30de79d658f6 888 void discardedFrame()
nixnax 29:30de79d658f6 889 {
nixnax 29:30de79d658f6 890 if (v0) {
nixnax 71:965619fedb3a 891 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 892 }
nixnax 9:0992486d4a30 893 }
nixnax 9:0992486d4a30 894
nixnax 29:30de79d658f6 895 void determinePacketType()
nixnax 29:30de79d658f6 896 {
nixnax 29:30de79d658f6 897 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 898 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 899 return;
nixnax 29:30de79d658f6 900 }
nixnax 29:30de79d658f6 901 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 902 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 903 return;
nixnax 29:30de79d658f6 904 }
nixnax 29:30de79d658f6 905 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 906 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 907 return;
nixnax 29:30de79d658f6 908 }
nixnax 9:0992486d4a30 909 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 910 switch (packetType) {
nixnax 29:30de79d658f6 911 case 0xc0:
nixnax 29:30de79d658f6 912 LCPframe();
nixnax 29:30de79d658f6 913 break; // link control
nixnax 29:30de79d658f6 914 case 0x80:
nixnax 29:30de79d658f6 915 IPCPframe();
nixnax 29:30de79d658f6 916 break; // IP control
nixnax 29:30de79d658f6 917 case 0x00:
nixnax 29:30de79d658f6 918 IPframe();
nixnax 29:30de79d658f6 919 break; // IP itself
nixnax 29:30de79d658f6 920 default:
nixnax 29:30de79d658f6 921 discardedFrame();
nixnax 9:0992486d4a30 922 }
nixnax 29:30de79d658f6 923 }
nixnax 9:0992486d4a30 924
nixnax 50:ad4e7c3c88e5 925 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 926 {
nixnax 85:53e57ff1cf05 927 while(1) {
nixnax 93:9675adc36882 928 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 929 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 930 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 931 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 932 if (rx==FRAME_7E) {
nixnax 81:9ede60e9a2c8 933 if (ppp.hdlc.frameFound == 0) { // we are still waiting for a frame start
nixnax 81:9ede60e9a2c8 934 ppp.hdlc.frameFound = 1; // we found our first frame start
nixnax 81:9ede60e9a2c8 935 ppp.hdlc.frameStartIndex=ppp.rx.tail; // remember where the frame character is in the buffer
nixnax 51:a86d56844324 936 } else {
nixnax 81:9ede60e9a2c8 937 // we have previously found a frame start
nixnax 81:9ede60e9a2c8 938 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 81:9ede60e9a2c8 939 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 93:9675adc36882 940 ppp.rx.rtail = ppp.rx.tail;
nixnax 81:9ede60e9a2c8 941 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 81:9ede60e9a2c8 942 break;
nixnax 50:ad4e7c3c88e5 943 }
nixnax 50:ad4e7c3c88e5 944 }
nixnax 50:ad4e7c3c88e5 945 }
nixnax 85:53e57ff1cf05 946 }
nixnax 50:ad4e7c3c88e5 947 }
nixnax 50:ad4e7c3c88e5 948
nixnax 29:30de79d658f6 949 void scanForConnectString()
nixnax 29:30de79d658f6 950 {
nixnax 81:9ede60e9a2c8 951 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 952 fillbuf();
nixnax 81:9ede60e9a2c8 953 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 81:9ede60e9a2c8 954 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENTCLIENT" );
nixnax 81:9ede60e9a2c8 955 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 956 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 957 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 958 if (found1 != NULL) {
nixnax 81:9ede60e9a2c8 959 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 81:9ede60e9a2c8 960 pc.puts("CLIENTSERVER");
nixnax 81:9ede60e9a2c8 961 if (v0) debug("Found connect string \"CLIENTCLIENT\"\n");
nixnax 81:9ede60e9a2c8 962 }
nixnax 81:9ede60e9a2c8 963 if (found2 != NULL) {
nixnax 81:9ede60e9a2c8 964 if (v0) debug("Found HDLC frame start (7E)\n");
nixnax 81:9ede60e9a2c8 965 }
nixnax 71:965619fedb3a 966 ppp.online=1; // we are connected, so stop looking for the string
nixnax 9:0992486d4a30 967 }
nixnax 9:0992486d4a30 968 }
nixnax 81:9ede60e9a2c8 969
nixnax 9:0992486d4a30 970 }
nixnax 9:0992486d4a30 971
nixnax 0:2cf4880c312a 972 int main()
nixnax 0:2cf4880c312a 973 {
nixnax 14:c65831c25aaa 974 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 975 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 976 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 977 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 978 #endif
nixnax 9:0992486d4a30 979 pppInitStruct(); // initialize all the PPP properties
nixnax 81:9ede60e9a2c8 980 ppp.seq=1000; // initial TCP sequence number
nixnax 81:9ede60e9a2c8 981
nixnax 0:2cf4880c312a 982 while(1) {
nixnax 51:a86d56844324 983 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 984 while(ppp.online) {
nixnax 81:9ede60e9a2c8 985 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 986 }
nixnax 7:ab147f5e97ac 987 }
nixnax 7:ab147f5e97ac 988 }