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@93:9675adc36882, 2017-07-24 (annotated)

Committer:
nixnax
Date:
Mon Jul 24 22:21:41 2017 +0000
Revision:
93:9675adc36882
Parent:
92:cb962b365cce
Child:
94:8ee3eec2a2bb
Changed TCP handler to wait for FIN; Comments

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 93:9675adc36882 1 // PPP-Blinky - "The Most Basic Internet Of Things"
nixnax 0:2cf4880c312a 2
nixnax 93:9675adc36882 3 // A Tiny Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax 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 29:30de79d658f6 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)
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 93:9675adc36882 39 #define SERIAL_PORT_MONITOR_YES /* 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 93:9675adc36882 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 50:ad4e7c3c88e5 203 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 204 {
nixnax 38:ab582987926e 205 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 206 if(start==end) {
nixnax 29:30de79d658f6 207 return;
nixnax 29:30de79d658f6 208 }
nixnax 9:0992486d4a30 209 crcReset();
nixnax 9:0992486d4a30 210 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 211 ppp.pkt.len=0;
nixnax 9:0992486d4a30 212 int unstuff=0;
nixnax 17:4918c893d802 213 int idx = start;
nixnax 17:4918c893d802 214 while(1) {
nixnax 9:0992486d4a30 215 if (unstuff==0) {
nixnax 72:ad3d12753acf 216 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 217 else {
nixnax 72:ad3d12753acf 218 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 219 ppp.pkt.len++;
nixnax 29:30de79d658f6 220 dest++;
nixnax 72:ad3d12753acf 221 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 222 }
nixnax 66:f005b9fdf4d1 223 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 224 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 225 ppp.pkt.len++;
nixnax 29:30de79d658f6 226 dest++;
nixnax 72:ad3d12753acf 227 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 228 unstuff=0;
nixnax 9:0992486d4a30 229 }
nixnax 81:9ede60e9a2c8 230 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 231 if (idx == end) break;
nixnax 9:0992486d4a30 232 }
nixnax 29:30de79d658f6 233 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 234 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 235 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 236 determinePacketType();
nixnax 90:55e0f243a7ce 237 } else {
nixnax 90:55e0f243a7ce 238 debug("PPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // ignore packets with CRC errors but print a debug line
nixnax 9:0992486d4a30 239 }
nixnax 9:0992486d4a30 240 }
nixnax 9:0992486d4a30 241
nixnax 38:ab582987926e 242 // Note - the hex output of dumpFrame() can be imported into WireShark
nixnax 38:ab582987926e 243 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 38:ab582987926e 244 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 29:30de79d658f6 245 void dumpFrame()
nixnax 29:30de79d658f6 246 {
nixnax 42:4de44be70bfd 247 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 42:4de44be70bfd 248 debug(" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len);
nixnax 16:cb0b80c24ba2 249 }
nixnax 16:cb0b80c24ba2 250
nixnax 29:30de79d658f6 251 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 252 {
nixnax 29:30de79d658f6 253 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 254 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 255 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 256 } else {
nixnax 29:30de79d658f6 257 pc.putc(ch);
nixnax 29:30de79d658f6 258 }
nixnax 11:f58998c24f0b 259 }
nixnax 9:0992486d4a30 260
nixnax 93:9675adc36882 261 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 262 {
nixnax 17:4918c893d802 263 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 264 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 265 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 266 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 93:9675adc36882 267 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 268 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 93:9675adc36882 269
nixnax 93:9675adc36882 270 if((i&0x7f)==0) fillbuf(); // handle received characters very every 128 sent
nixnax 93:9675adc36882 271 }
nixnax 16:cb0b80c24ba2 272 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 273 }
nixnax 9:0992486d4a30 274
nixnax 93:9675adc36882 275 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 276 {
nixnax 93:9675adc36882 277 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 278 ppp.pkt.buf[4]=2; // change code to ack
nixnax 93:9675adc36882 279 send_pppFrame(); // simply acknowledge everything they ask for
nixnax 93:9675adc36882 280 debug("Our IPCP Ask\n");
nixnax 92:cb962b365cce 281 // send our own request now
nixnax 92:cb962b365cce 282 ppp.pkt.buf[4]=1; // change code to request
nixnax 92:cb962b365cce 283 ppp.pkt.buf[5]++; // increment sequence number
nixnax 92:cb962b365cce 284 ppp.pkt.buf[7]=4; // no options requested
nixnax 93:9675adc36882 285 send_pppFrame(); // this is our request
nixnax 92:cb962b365cce 286 return;
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 26:11f4eb2663a7 475 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 476 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 26:11f4eb2663a7 477 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 478 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 479 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 480 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 481 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 482 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 483 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 484 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 485 char * protocol = ipPkt+9; // 1 byte
nixnax 77:abf92baebb42 486 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 487 #endif
nixnax 26:11f4eb2663a7 488 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 489 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 490
nixnax 55:43faae812be3 491 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 29:30de79d658f6 492 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 493 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 494 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 495 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 496 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 497 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 498 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 499 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 500 int protocolIP = protocol[0];
nixnax 76:00e208cceb8b 501 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 502 #endif
nixnax 55:43faae812be3 503
nixnax 29:30de79d658f6 504 char srcIP [16];
nixnax 29:30de79d658f6 505 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 29:30de79d658f6 506 char dstIP [16];
nixnax 29:30de79d658f6 507 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 82:051f77f7dd72 508 if (v0) debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 42:4de44be70bfd 509 if (v0) debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 29:30de79d658f6 510 }
nixnax 26:11f4eb2663a7 511
nixnax 29:30de79d658f6 512 void dumpHeaderTCP()
nixnax 29:30de79d658f6 513 {
nixnax 83:cdcb81d1910f 514 if( v0 ) {
nixnax 81:9ede60e9a2c8 515
nixnax 81:9ede60e9a2c8 516 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 517 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 518 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 519 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 520 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 521 #endif
nixnax 81:9ede60e9a2c8 522 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 523 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 524 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 525 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 526 #endif
nixnax 81:9ede60e9a2c8 527 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 528
nixnax 81:9ede60e9a2c8 529 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 530 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 531 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 532
nixnax 81:9ede60e9a2c8 533 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 534 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 535 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 536 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 537 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 538 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 539 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 540 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 541 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 542 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 543 }
nixnax 29:30de79d658f6 544 }
nixnax 29:30de79d658f6 545
nixnax 68:0b74763ae67f 546 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 547 {
nixnax 67:a63e3486bcda 548 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 549 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 550 int contentLengthStart; // index where HTML starts
nixnax 93:9675adc36882 551 int xFetch, httpGetRoot; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 552
nixnax 87:9f5ac1fabd95 553 ppp.httpFrameCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 554
nixnax 93:9675adc36882 555 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.1", 14); // found GET /
nixnax 89:2c8dd0c2a426 556 xFetch = strncmp(dataStart, "GET /x HTTP/1.1", 15); // found GET /x
nixnax 93:9675adc36882 557 if( (httpGetRoot==0) || (xFetch==0) ) {
nixnax 89:2c8dd0c2a426 558 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 559 } else {
nixnax 89:2c8dd0c2a426 560 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 561 }
nixnax 83:cdcb81d1910f 562 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 563 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 564 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 565 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 566 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 567 nHeader=n; // size of HTTP header
nixnax 93:9675adc36882 568 if( httpGetRoot == 0 ) {
nixnax 83:cdcb81d1910f 569 // this is where we insert our web page into the buffer
nixnax 93:9675adc36882 570 //n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 93:9675adc36882 571 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 93:9675adc36882 572 n = n + sizeof(rootWebPage);
nixnax 85:53e57ff1cf05 573 } else {
nixnax 89:2c8dd0c2a426 574 if (xFetch == 0) {
nixnax 89:2c8dd0c2a426 575
nixnax 89:2c8dd0c2a426 576 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 89:2c8dd0c2a426 577 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 89:2c8dd0c2a426 578 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 89:2c8dd0c2a426 579 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed-ppp-blinky</title>"); // html title (W3C.org required element)
nixnax 93:9675adc36882 580 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.buflevel); // ppp.httpFrameCount); // body = the http frame count
nixnax 89:2c8dd0c2a426 581 #else
nixnax 89:2c8dd0c2a426 582 n=n+sprintf(n+dataStart,"%d",ppp.httpFrameCount); // not valid html but fast, most browsers and curl are ok with it
nixnax 89:2c8dd0c2a426 583 #endif
nixnax 89:2c8dd0c2a426 584
nixnax 89:2c8dd0c2a426 585 } else {
nixnax 89:2c8dd0c2a426 586 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 89:2c8dd0c2a426 587 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky-mbed</title>"); // html title (required element)
nixnax 89:2c8dd0c2a426 588 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 89:2c8dd0c2a426 589 }
nixnax 83:cdcb81d1910f 590 }
nixnax 87:9f5ac1fabd95 591 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 592 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 593
nixnax 83:cdcb81d1910f 594 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 595 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 596 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 597 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 598
nixnax 77:abf92baebb42 599 if (v2) {
nixnax 77:abf92baebb42 600 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 601 }
nixnax 67:a63e3486bcda 602 return n; // total byte size of our response
nixnax 67:a63e3486bcda 603 }
nixnax 67:a63e3486bcda 604
nixnax 67:a63e3486bcda 605
nixnax 29:30de79d658f6 606 void tcpHandler()
nixnax 29:30de79d658f6 607 {
nixnax 87:9f5ac1fabd95 608 // IP header
nixnax 87:9f5ac1fabd95 609
nixnax 26:11f4eb2663a7 610 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 611 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 612 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 613 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 614 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 615 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 616 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 617 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 618 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 619 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 620
nixnax 87:9f5ac1fabd95 621 // TCP header
nixnax 87:9f5ac1fabd95 622
nixnax 87:9f5ac1fabd95 623 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 624 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 625 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 626 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 627 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 628 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 629 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 630 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 631 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 632
nixnax 26:11f4eb2663a7 633 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 634 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 635 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 636
nixnax 87:9f5ac1fabd95 637 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 638 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 639 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 640
nixnax 85:53e57ff1cf05 641 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 642 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 643
nixnax 85:53e57ff1cf05 644 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 645 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 646
nixnax 28:1aa629be05e7 647
nixnax 29:30de79d658f6 648 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 649 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 650 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 651 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 652 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 653
nixnax 87:9f5ac1fabd95 654 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 655 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 656
nixnax 87:9f5ac1fabd95 657 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 658 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 659 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 660 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 661 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 662 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 663
nixnax 35:e7068df4d971 664 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 665 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 666 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 667
nixnax 91:5141ae9fba53 668 windowsizetcp[0]=3; // ignore window size negotiation
nixnax 91:5141ae9fba53 669 windowsizetcp[1]=0; // ignore winodw size negotiation
nixnax 38:ab582987926e 670
nixnax 93:9675adc36882 671 int doFin = 0; // flag to see if we have to send an extra FIN message to shut down the link
nixnax 93:9675adc36882 672
nixnax 69:23f560087c16 673 // A sparse TCP flag interpreter that implements simple TCP connections from a single source
nixnax 69:23f560087c16 674 // Clients are allowed ONE push packet, after which the link is closed with a FIN flag in the ACK packet
nixnax 69:23f560087c16 675 // This strategy allows web browsers, netcat and curl to work ok while keeping the state machine simple
nixnax 77:abf92baebb42 676
nixnax 69:23f560087c16 677 switch ( flagsTCP ) {
nixnax 69:23f560087c16 678 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 679 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 680 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 681 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 682 break;
nixnax 77:abf92baebb42 683 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 93:9675adc36882 684 flagsOut = TCP_FLAG_ACK ; //| TCP_FLAG_FIN; // for every push we answer once AND close the link
nixnax 91:5141ae9fba53 685 windowsizetcp[0]=1; // reduce the receive window size even more
nixnax 87:9f5ac1fabd95 686 if ( strncmp(tcpDataIn, "GET ", 4) == 0) { // check for an http GET command
nixnax 87:9f5ac1fabd95 687 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 69:23f560087c16 688 }
nixnax 69:23f560087c16 689 break;
nixnax 77:abf92baebb42 690 case TCP_FLAG_FIN:
nixnax 69:23f560087c16 691 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 93:9675adc36882 692 case TCP_FLAG_RST:
nixnax 93:9675adc36882 693 doFin = 1; // they want to tear down the link, so we must send a FIN packet also
nixnax 85:53e57ff1cf05 694 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 695 break;
nixnax 77:abf92baebb42 696 default:
nixnax 69:23f560087c16 697 return; // ignore remaining packets
nixnax 93:9675adc36882 698 } // switch
nixnax 77:abf92baebb42 699
nixnax 69:23f560087c16 700 // The TCP flag handling is now done
nixnax 93:9675adc36882 701
nixnax 93:9675adc36882 702 // first we swap sourc and destination TCP addresses and insert the new ack and seq numbers
nixnax 93:9675adc36882 703
nixnax 65:23b17c43aa0f 704 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 705 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 706 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 707 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 708
nixnax 60:2b770949c911 709 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 710 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 711 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 93:9675adc36882 712
nixnax 93:9675adc36882 713 sendTCP:
nixnax 83:cdcb81d1910f 714
nixnax 85:53e57ff1cf05 715 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 716 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 717 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 718 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 719
nixnax 85:53e57ff1cf05 720 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 721 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 722 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 723 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 724
nixnax 93:9675adc36882 725 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 726
nixnax 93:9675adc36882 727 // increment the ip ident number
nixnax 38:ab582987926e 728
nixnax 93:9675adc36882 729 ppp.ident++; // get next ident number for our packet
nixnax 93:9675adc36882 730 ident[0] = ppp.ident>>8;
nixnax 93:9675adc36882 731 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 732
nixnax 93:9675adc36882 733 // Now we recalculate all the header sizes, and do the IP and TCP checksums
nixnax 38:ab582987926e 734 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 735 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 736 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 737 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 738 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 739
nixnax 38:ab582987926e 740 // the header is all set up, now do the IP and TCP checksums
nixnax 36:2a9b457f8276 741
nixnax 61:b3c1a04efd0a 742 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 743 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 744 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 745
nixnax 64:677b9713a120 746 // 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 747 // 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 748
nixnax 87:9f5ac1fabd95 749 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 750 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 751 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 752 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 753 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 754 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 755 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 756
nixnax 61:b3c1a04efd0a 757 // pseudo-header built, now we can calculate TCP checksum
nixnax 63:9253b0e1b7d8 758
nixnax 29:30de79d658f6 759 checksumtcp[0]=0;
nixnax 29:30de79d658f6 760 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 761 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 762 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 763 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 764 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 93:9675adc36882 765
nixnax 93:9675adc36882 766 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 60:2b770949c911 767
nixnax 93:9675adc36882 768 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 769 doFin=0;
nixnax 93:9675adc36882 770 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // tell them we are also finished
nixnax 93:9675adc36882 771 goto sendTCP; // send our final packet for this conversation.
nixnax 93:9675adc36882 772 }
nixnax 93:9675adc36882 773
nixnax 83:cdcb81d1910f 774 dumpHeaderIP();
nixnax 93:9675adc36882 775 //dumpHeaderTCP();
nixnax 93:9675adc36882 776
nixnax 29:30de79d658f6 777 }
nixnax 26:11f4eb2663a7 778
nixnax 29:30de79d658f6 779 void dumpDataTCP()
nixnax 29:30de79d658f6 780 {
nixnax 26:11f4eb2663a7 781 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 782 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 783 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 784 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 785 if (v1) {
nixnax 42:4de44be70bfd 786 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 787 }
nixnax 29:30de79d658f6 788 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 789 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 790 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 791 }
nixnax 29:30de79d658f6 792 }
nixnax 26:11f4eb2663a7 793
nixnax 29:30de79d658f6 794 void TCPpacket()
nixnax 29:30de79d658f6 795 {
nixnax 83:cdcb81d1910f 796 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 797 dumpHeaderTCP();
nixnax 77:abf92baebb42 798 if (v2) {
nixnax 77:abf92baebb42 799 dumpDataTCP();
nixnax 77:abf92baebb42 800 }
nixnax 26:11f4eb2663a7 801 tcpHandler();
nixnax 11:f58998c24f0b 802 }
nixnax 11:f58998c24f0b 803
nixnax 29:30de79d658f6 804 void otherProtocol()
nixnax 29:30de79d658f6 805 {
nixnax 64:677b9713a120 806 debug("Other IP protocol");
nixnax 29:30de79d658f6 807 }
nixnax 26:11f4eb2663a7 808
nixnax 29:30de79d658f6 809 void IPframe()
nixnax 29:30de79d658f6 810 {
nixnax 10:74f8233f72c0 811 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 812 switch (protocol) {
nixnax 29:30de79d658f6 813 case 1:
nixnax 29:30de79d658f6 814 ICMPpacket();
nixnax 29:30de79d658f6 815 break;
nixnax 29:30de79d658f6 816 case 2:
nixnax 29:30de79d658f6 817 IGMPpacket();
nixnax 29:30de79d658f6 818 break;
nixnax 29:30de79d658f6 819 case 17:
nixnax 29:30de79d658f6 820 UDPpacket();
nixnax 29:30de79d658f6 821 break;
nixnax 29:30de79d658f6 822 case 6:
nixnax 29:30de79d658f6 823 TCPpacket();
nixnax 29:30de79d658f6 824 break;
nixnax 29:30de79d658f6 825 default:
nixnax 29:30de79d658f6 826 otherProtocol();
nixnax 29:30de79d658f6 827 }
nixnax 29:30de79d658f6 828 }
nixnax 9:0992486d4a30 829
nixnax 29:30de79d658f6 830 void LCPconfReq()
nixnax 29:30de79d658f6 831 {
nixnax 64:677b9713a120 832 debug("LCP Config ");
nixnax 9:0992486d4a30 833 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 834 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 835 debug("Reject\n");
nixnax 93:9675adc36882 836 send_pppFrame();
nixnax 9:0992486d4a30 837 } else {
nixnax 9:0992486d4a30 838 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 839 debug("Ack\n");
nixnax 93:9675adc36882 840 send_pppFrame();
nixnax 64:677b9713a120 841 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 842 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 843 send_pppFrame();
nixnax 9:0992486d4a30 844 }
nixnax 9:0992486d4a30 845 }
nixnax 9:0992486d4a30 846
nixnax 29:30de79d658f6 847 void LCPconfAck()
nixnax 29:30de79d658f6 848 {
nixnax 64:677b9713a120 849 debug("LCP Ack\n");
nixnax 29:30de79d658f6 850 }
nixnax 9:0992486d4a30 851
nixnax 29:30de79d658f6 852 void LCPend()
nixnax 29:30de79d658f6 853 {
nixnax 29:30de79d658f6 854 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 855 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 856 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 857 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 858 debug("LCP End\n");
nixnax 9:0992486d4a30 859 }
nixnax 9:0992486d4a30 860
nixnax 29:30de79d658f6 861 void LCPother()
nixnax 29:30de79d658f6 862 {
nixnax 64:677b9713a120 863 debug("LCP Other\n");
nixnax 29:30de79d658f6 864 dumpFrame();
nixnax 29:30de79d658f6 865 }
nixnax 29:30de79d658f6 866
nixnax 29:30de79d658f6 867 void LCPframe()
nixnax 29:30de79d658f6 868 {
nixnax 29:30de79d658f6 869 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 870 switch (code) {
nixnax 29:30de79d658f6 871 case 1:
nixnax 29:30de79d658f6 872 LCPconfReq();
nixnax 29:30de79d658f6 873 break; // config request
nixnax 29:30de79d658f6 874 case 2:
nixnax 29:30de79d658f6 875 LCPconfAck();
nixnax 29:30de79d658f6 876 break; // config ack
nixnax 29:30de79d658f6 877 case 5:
nixnax 29:30de79d658f6 878 LCPend();
nixnax 29:30de79d658f6 879 break; // end connection
nixnax 29:30de79d658f6 880 default:
nixnax 29:30de79d658f6 881 LCPother();
nixnax 29:30de79d658f6 882 }
nixnax 9:0992486d4a30 883 }
nixnax 9:0992486d4a30 884
nixnax 29:30de79d658f6 885 void discardedFrame()
nixnax 29:30de79d658f6 886 {
nixnax 29:30de79d658f6 887 if (v0) {
nixnax 71:965619fedb3a 888 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 889 }
nixnax 9:0992486d4a30 890 }
nixnax 9:0992486d4a30 891
nixnax 29:30de79d658f6 892 void determinePacketType()
nixnax 29:30de79d658f6 893 {
nixnax 29:30de79d658f6 894 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 895 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 896 return;
nixnax 29:30de79d658f6 897 }
nixnax 29:30de79d658f6 898 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 899 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 900 return;
nixnax 29:30de79d658f6 901 }
nixnax 29:30de79d658f6 902 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 903 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 904 return;
nixnax 29:30de79d658f6 905 }
nixnax 9:0992486d4a30 906 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 907 switch (packetType) {
nixnax 29:30de79d658f6 908 case 0xc0:
nixnax 29:30de79d658f6 909 LCPframe();
nixnax 29:30de79d658f6 910 break; // link control
nixnax 29:30de79d658f6 911 case 0x80:
nixnax 29:30de79d658f6 912 IPCPframe();
nixnax 29:30de79d658f6 913 break; // IP control
nixnax 29:30de79d658f6 914 case 0x00:
nixnax 29:30de79d658f6 915 IPframe();
nixnax 29:30de79d658f6 916 break; // IP itself
nixnax 29:30de79d658f6 917 default:
nixnax 29:30de79d658f6 918 discardedFrame();
nixnax 9:0992486d4a30 919 }
nixnax 29:30de79d658f6 920 }
nixnax 9:0992486d4a30 921
nixnax 50:ad4e7c3c88e5 922 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 923 {
nixnax 85:53e57ff1cf05 924 while(1) {
nixnax 93:9675adc36882 925 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 926 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 927 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 928 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 929 if (rx==FRAME_7E) {
nixnax 81:9ede60e9a2c8 930 if (ppp.hdlc.frameFound == 0) { // we are still waiting for a frame start
nixnax 81:9ede60e9a2c8 931 ppp.hdlc.frameFound = 1; // we found our first frame start
nixnax 81:9ede60e9a2c8 932 ppp.hdlc.frameStartIndex=ppp.rx.tail; // remember where the frame character is in the buffer
nixnax 51:a86d56844324 933 } else {
nixnax 81:9ede60e9a2c8 934 // we have previously found a frame start
nixnax 81:9ede60e9a2c8 935 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 81:9ede60e9a2c8 936 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 93:9675adc36882 937 ppp.rx.rtail = ppp.rx.tail;
nixnax 81:9ede60e9a2c8 938 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 81:9ede60e9a2c8 939 break;
nixnax 50:ad4e7c3c88e5 940 }
nixnax 50:ad4e7c3c88e5 941 }
nixnax 50:ad4e7c3c88e5 942 }
nixnax 85:53e57ff1cf05 943 }
nixnax 50:ad4e7c3c88e5 944 }
nixnax 50:ad4e7c3c88e5 945
nixnax 29:30de79d658f6 946 void scanForConnectString()
nixnax 29:30de79d658f6 947 {
nixnax 81:9ede60e9a2c8 948 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 949 fillbuf();
nixnax 81:9ede60e9a2c8 950 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 81:9ede60e9a2c8 951 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENTCLIENT" );
nixnax 81:9ede60e9a2c8 952 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 953 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 954 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 955 if (found1 != NULL) {
nixnax 81:9ede60e9a2c8 956 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 81:9ede60e9a2c8 957 pc.puts("CLIENTSERVER");
nixnax 81:9ede60e9a2c8 958 if (v0) debug("Found connect string \"CLIENTCLIENT\"\n");
nixnax 81:9ede60e9a2c8 959 }
nixnax 81:9ede60e9a2c8 960 if (found2 != NULL) {
nixnax 81:9ede60e9a2c8 961 if (v0) debug("Found HDLC frame start (7E)\n");
nixnax 81:9ede60e9a2c8 962 }
nixnax 71:965619fedb3a 963 ppp.online=1; // we are connected, so stop looking for the string
nixnax 9:0992486d4a30 964 }
nixnax 9:0992486d4a30 965 }
nixnax 81:9ede60e9a2c8 966
nixnax 9:0992486d4a30 967 }
nixnax 9:0992486d4a30 968
nixnax 0:2cf4880c312a 969 int main()
nixnax 0:2cf4880c312a 970 {
nixnax 14:c65831c25aaa 971 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 972 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 973 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 974 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 975 #endif
nixnax 9:0992486d4a30 976 pppInitStruct(); // initialize all the PPP properties
nixnax 81:9ede60e9a2c8 977 ppp.seq=1000; // initial TCP sequence number
nixnax 81:9ede60e9a2c8 978
nixnax 0:2cf4880c312a 979 while(1) {
nixnax 51:a86d56844324 980 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 981 while(ppp.online) {
nixnax 81:9ede60e9a2c8 982 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 983 }
nixnax 7:ab147f5e97ac 984 }
nixnax 7:ab147f5e97ac 985 }