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@108:f77ec4605945, 2017-08-04 (annotated)

Committer:
nixnax
Date:
Fri Aug 04 03:34:11 2017 +0000
Revision:
108:f77ec4605945
Parent:
107:5fe806713d49
Child:
109:644a59ebb5b1
Added link to Windows Dial-up Configuration.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 93:9675adc36882 1 // PPP-Blinky - "The Most Basic Internet Of Things"
nixnax 0:2cf4880c312a 2
nixnax 93:9675adc36882 3 // A Tiny Webserver Using Windows XP/7/8/10/Linux Dial-Up Networking Over A Serial Port.
nixnax 41:e58a5a09f411 4 // Also receives UDP packets and responds to ping (ICMP Echo requests)
nixnax 4:a469050d5b80 5
nixnax 93:9675adc36882 6 // Copyright 2016/2017 Nicolas Nackel aka Nixnax. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
nixnax 81:9ede60e9a2c8 7
nixnax 41:e58a5a09f411 8 // Notes and Instructions
nixnax 41:e58a5a09f411 9 // http://bit.ly/PPP-Blinky-Instructions
nixnax 108:f77ec4605945 10 // http://bit.ly/win-rasdial-config
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 106:d14e6b597ca3 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 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 103 int ledState; // state of LED1
nixnax 98:3babad0d1bd4 104 int httpPageCount;
nixnax 4:a469050d5b80 105 struct {
nixnax 105:45001195b325 106 #define RXBUFLEN (1<<11)
nixnax 93:9675adc36882 107 // the serial port receive buffer and packet buffer, size is RXBUFLEN (currently 8192 bytes)
nixnax 85:53e57ff1cf05 108 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 93:9675adc36882 109 int head;
nixnax 93:9675adc36882 110 int tail;
nixnax 95:40af49390daf 111 int rtail;
nixnax 93:9675adc36882 112 int buflevel;
nixnax 38:ab582987926e 113 } rx; // serial port objects
nixnax 4:a469050d5b80 114 struct {
nixnax 38:ab582987926e 115 int len; // number of bytes in buffer
nixnax 38:ab582987926e 116 int crc; // PPP CRC (frame check)
nixnax 77:abf92baebb42 117 #define TCP_max_size 3300
nixnax 77:abf92baebb42 118 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 119 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 120 struct {
nixnax 50:ad4e7c3c88e5 121 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 122 int frameEndIndex; // frame end marker
nixnax 50:ad4e7c3c88e5 123 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 124 };
nixnax 31:e000c1b9c565 125
nixnax 29:30de79d658f6 126 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 127
nixnax 93:9675adc36882 128 // Initialize our global structure, clear the buffer, etc.
nixnax 29:30de79d658f6 129 void pppInitStruct()
nixnax 29:30de79d658f6 130 {
nixnax 81:9ede60e9a2c8 131 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 132 ppp.online=0;
nixnax 29:30de79d658f6 133 ppp.rx.tail=0;
nixnax 93:9675adc36882 134 ppp.rx.rtail=0;
nixnax 29:30de79d658f6 135 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 136 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 137 ppp.pkt.len=0;
nixnax 83:cdcb81d1910f 138 ppp.ident=1000;
nixnax 29:30de79d658f6 139 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 140 ppp.hdlc.frameStartIndex=0;
nixnax 98:3babad0d1bd4 141 ppp.httpPageCount=0;
nixnax 29:30de79d658f6 142 }
nixnax 26:11f4eb2663a7 143
nixnax 43:aa57db08995d 144 void led1Toggle()
nixnax 43:aa57db08995d 145 {
nixnax 43:aa57db08995d 146 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 93:9675adc36882 147 led1 = ppp.ledState; // toggle led
nixnax 43:aa57db08995d 148 }
nixnax 43:aa57db08995d 149
nixnax 29:30de79d658f6 150 void crcReset()
nixnax 29:30de79d658f6 151 {
nixnax 29:30de79d658f6 152 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 153 }
nixnax 4:a469050d5b80 154
nixnax 29:30de79d658f6 155 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 156 {
nixnax 29:30de79d658f6 157 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 158 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 159 x>>=1;
nixnax 29:30de79d658f6 160 }
nixnax 29:30de79d658f6 161 }
nixnax 29:30de79d658f6 162
nixnax 29:30de79d658f6 163 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 164 {
nixnax 31:e000c1b9c565 165 crcReset();
nixnax 31:e000c1b9c565 166 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 167 return ppp.crc;
nixnax 29:30de79d658f6 168 }
nixnax 0:2cf4880c312a 169
nixnax 85:53e57ff1cf05 170 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 171 void fillbuf()
nixnax 0:2cf4880c312a 172 {
nixnax 107:5fe806713d49 173 char ch;
nixnax 85:53e57ff1cf05 174 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 175 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 93:9675adc36882 176 if ( hd == ppp.rx.rtail ) {
nixnax 85:53e57ff1cf05 177 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 178 return;
nixnax 83:cdcb81d1910f 179 }
nixnax 107:5fe806713d49 180 ch = pc.getc(); // read new character
nixnax 107:5fe806713d49 181 ppp.rx.buf[ppp.rx.head] = ch; // insert in our receive buffer
nixnax 107:5fe806713d49 182 if ( ppp.online == 0 ) {
nixnax 107:5fe806713d49 183 if (ch == 0x7E) {
nixnax 107:5fe806713d49 184 ppp.online = 1;
nixnax 107:5fe806713d49 185 debug("HDLC Frame (0x7E)\n");
nixnax 107:5fe806713d49 186 }
nixnax 107:5fe806713d49 187 }
nixnax 20:5db9b77b38a6 188 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 189 ppp.rx.buflevel++;
nixnax 15:b0154c910143 190 }
nixnax 0:2cf4880c312a 191 }
nixnax 0:2cf4880c312a 192
nixnax 85:53e57ff1cf05 193 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 194 {
nixnax 43:aa57db08995d 195 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 196 return emptyStatus;
nixnax 0:2cf4880c312a 197 }
nixnax 0:2cf4880c312a 198
nixnax 85:53e57ff1cf05 199 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 200 {
nixnax 63:9253b0e1b7d8 201 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 202 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 203 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 204 return x;
nixnax 0:2cf4880c312a 205 }
nixnax 0:2cf4880c312a 206
nixnax 95:40af49390daf 207 // Note - the hex output of dumpPPPFrame() can be imported into WireShark
nixnax 95:40af49390daf 208 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 95:40af49390daf 209 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 95:40af49390daf 210 void dumpPPPFrame()
nixnax 95:40af49390daf 211 {
nixnax 95:40af49390daf 212 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 95:40af49390daf 213 debug(" CRC=%04x Len=%d\n", ppp.pkt.crc, ppp.pkt.len);
nixnax 95:40af49390daf 214 }
nixnax 95:40af49390daf 215
nixnax 50:ad4e7c3c88e5 216 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 217 {
nixnax 38:ab582987926e 218 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 219 if(start==end) {
nixnax 29:30de79d658f6 220 return;
nixnax 29:30de79d658f6 221 }
nixnax 9:0992486d4a30 222 crcReset();
nixnax 9:0992486d4a30 223 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 224 ppp.pkt.len=0;
nixnax 9:0992486d4a30 225 int unstuff=0;
nixnax 17:4918c893d802 226 int idx = start;
nixnax 17:4918c893d802 227 while(1) {
nixnax 9:0992486d4a30 228 if (unstuff==0) {
nixnax 72:ad3d12753acf 229 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 230 else {
nixnax 72:ad3d12753acf 231 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 232 ppp.pkt.len++;
nixnax 29:30de79d658f6 233 dest++;
nixnax 72:ad3d12753acf 234 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 235 }
nixnax 66:f005b9fdf4d1 236 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 237 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 238 ppp.pkt.len++;
nixnax 29:30de79d658f6 239 dest++;
nixnax 72:ad3d12753acf 240 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 241 unstuff=0;
nixnax 9:0992486d4a30 242 }
nixnax 81:9ede60e9a2c8 243 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 244 if (idx == end) break;
nixnax 9:0992486d4a30 245 }
nixnax 29:30de79d658f6 246 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 247 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 248 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 249 determinePacketType();
nixnax 90:55e0f243a7ce 250 } else {
nixnax 95:40af49390daf 251 if (0) { // don't normally report FCS because windows early-terminates packets, and early-terminated packets all have FCS errors.
nixnax 95:40af49390daf 252 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 253 }
nixnax 9:0992486d4a30 254 }
nixnax 9:0992486d4a30 255 }
nixnax 9:0992486d4a30 256
nixnax 29:30de79d658f6 257 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 258 {
nixnax 29:30de79d658f6 259 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 260 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 261 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 262 } else {
nixnax 29:30de79d658f6 263 pc.putc(ch);
nixnax 29:30de79d658f6 264 }
nixnax 11:f58998c24f0b 265 }
nixnax 9:0992486d4a30 266
nixnax 93:9675adc36882 267 void send_pppFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 268 {
nixnax 17:4918c893d802 269 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 270 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 271 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 272 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 95:40af49390daf 273 for(int i=0; i<ppp.pkt.len; i++) {
nixnax 93:9675adc36882 274 hdlcPut( ppp.pkt.buf[i] ); // send a character
nixnax 107:5fe806713d49 275 if((i&0x7f)==0) fillbuf(); // handle received characters every 128 sent
nixnax 93:9675adc36882 276 }
nixnax 16:cb0b80c24ba2 277 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 278 }
nixnax 9:0992486d4a30 279
nixnax 93:9675adc36882 280 void ipcpConfigRequestHandler()
nixnax 29:30de79d658f6 281 {
nixnax 93:9675adc36882 282 debug("Their IPCP Config Req, Our Ack\n");
nixnax 92:cb962b365cce 283 ppp.pkt.buf[4]=2; // change code to ack
nixnax 108:f77ec4605945 284 send_pppFrame(); // acknowledge everything they ask for - assume it's IP addresses
nixnax 106:d14e6b597ca3 285
nixnax 107:5fe806713d49 286 debug("Our IPCP Ask (no options)\n");
nixnax 92:cb962b365cce 287 ppp.pkt.buf[4]=1; // change code to request
nixnax 106:d14e6b597ca3 288 ppp.pkt.buf[7]=4; // no options in this request
nixnax 106:d14e6b597ca3 289 ppp.pkt.len=10; // no options in this request shortest ipcp packet possible (4 ppp + 4 ipcp + 2 crc)
nixnax 103:4f5512dd11cf 290 send_pppFrame(); // send our request
nixnax 9:0992486d4a30 291 }
nixnax 9:0992486d4a30 292
nixnax 93:9675adc36882 293 void ipcpAckHandler()
nixnax 29:30de79d658f6 294 {
nixnax 93:9675adc36882 295 debug("Their IPCP Grant\n");
nixnax 29:30de79d658f6 296 }
nixnax 9:0992486d4a30 297
nixnax 93:9675adc36882 298 void ipcpNackHandler()
nixnax 29:30de79d658f6 299 {
nixnax 106:d14e6b597ca3 300 debug("Their IPCP Nack, Our ACK\n");
nixnax 107:5fe806713d49 301 if (ppp.pkt.buf[8]==3) { // check if the NACK contains an IP address parameter
nixnax 106:d14e6b597ca3 302 ppp.pkt.buf[4]=1; // assume the NACK contains our "suggested" IP address
nixnax 106:d14e6b597ca3 303 send_pppFrame(); // let's request this IP address as ours
nixnax 106:d14e6b597ca3 304 } // if it's not an IP nack we ignore it
nixnax 29:30de79d658f6 305 }
nixnax 9:0992486d4a30 306
nixnax 93:9675adc36882 307 void ipcpDefaultHandler()
nixnax 29:30de79d658f6 308 {
nixnax 93:9675adc36882 309 debug("Their IPCP Other\n");
nixnax 29:30de79d658f6 310 }
nixnax 29:30de79d658f6 311
nixnax 29:30de79d658f6 312 void IPCPframe()
nixnax 29:30de79d658f6 313 {
nixnax 9:0992486d4a30 314 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 315 switch (code) {
nixnax 29:30de79d658f6 316 case 1:
nixnax 93:9675adc36882 317 ipcpConfigRequestHandler();
nixnax 29:30de79d658f6 318 break;
nixnax 29:30de79d658f6 319 case 2:
nixnax 93:9675adc36882 320 ipcpAckHandler();
nixnax 29:30de79d658f6 321 break;
nixnax 29:30de79d658f6 322 case 3:
nixnax 93:9675adc36882 323 ipcpNackHandler();
nixnax 29:30de79d658f6 324 break;
nixnax 29:30de79d658f6 325 default:
nixnax 93:9675adc36882 326 ipcpDefaultHandler();
nixnax 9:0992486d4a30 327 }
nixnax 29:30de79d658f6 328 }
nixnax 9:0992486d4a30 329
nixnax 29:30de79d658f6 330 void UDPpacket()
nixnax 29:30de79d658f6 331 {
nixnax 12:db0dc91f0231 332 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 333 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 334 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 335 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 336 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 337 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 338 #endif
nixnax 12:db0dc91f0231 339 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 340 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 341 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 342 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 343 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 344 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 345 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 346 #endif
nixnax 29:30de79d658f6 347 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 348 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 349 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 350 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 351 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 352 int printSize = udpLength;
nixnax 29:30de79d658f6 353 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 354 if (v1) {
nixnax 29:30de79d658f6 355 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 356 char ch = udpInf[i];
nixnax 29:30de79d658f6 357 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 358 debug("%c", ch);
nixnax 29:30de79d658f6 359 } else {
nixnax 64:677b9713a120 360 debug("_");
nixnax 29:30de79d658f6 361 }
nixnax 29:30de79d658f6 362 }
nixnax 29:30de79d658f6 363 }
nixnax 83:cdcb81d1910f 364 if (v0) debug("\n");
nixnax 12:db0dc91f0231 365 }
nixnax 11:f58998c24f0b 366
nixnax 76:00e208cceb8b 367 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 368 {
nixnax 77:abf92baebb42 369
nixnax 75:0d513869231f 370 unsigned int sum=0;
nixnax 76:00e208cceb8b 371 unsigned char placeHolder;
nixnax 29:30de79d658f6 372 if (len&1) {
nixnax 76:00e208cceb8b 373 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 374 ptr[len]=0;
nixnax 29:30de79d658f6 375 }
nixnax 29:30de79d658f6 376 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 377 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 378 ptr++;
nixnax 76:00e208cceb8b 379 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 380 ptr++;
nixnax 76:00e208cceb8b 381 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 382 sum = sum + val;
nixnax 11:f58998c24f0b 383 }
nixnax 29:30de79d658f6 384 if (len&1) {
nixnax 76:00e208cceb8b 385 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 386 }
nixnax 76:00e208cceb8b 387 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 388 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 389 return ~sum;
nixnax 29:30de79d658f6 390 }
nixnax 11:f58998c24f0b 391
nixnax 29:30de79d658f6 392 void headerCheckSum()
nixnax 29:30de79d658f6 393 {
nixnax 11:f58998c24f0b 394 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 395 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 396 int sum=0;
nixnax 11:f58998c24f0b 397
nixnax 29:30de79d658f6 398 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 399 int hi = *ptr;
nixnax 29:30de79d658f6 400 ptr++;
nixnax 29:30de79d658f6 401 int lo = *ptr;
nixnax 29:30de79d658f6 402 ptr++;
nixnax 11:f58998c24f0b 403 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 404 sum = sum + val;
nixnax 11:f58998c24f0b 405 }
nixnax 11:f58998c24f0b 406 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 407 sum = ~sum;
nixnax 11:f58998c24f0b 408 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 409 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 410 }
nixnax 9:0992486d4a30 411
nixnax 29:30de79d658f6 412 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 413 {
nixnax 12:db0dc91f0231 414 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 415 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 416 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 417 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 418 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 419 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 420 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 421 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 422 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 423 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 424 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 425 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 426 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 427 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 428 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 429 #endif
nixnax 81:9ede60e9a2c8 430 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 431 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 432 char src[4];
nixnax 29:30de79d658f6 433 char dst[4];
nixnax 12:db0dc91f0231 434 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 435 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 436 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 437 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 438 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 439 chkSum[0]=0;
nixnax 29:30de79d658f6 440 chkSum[1]=0;
nixnax 12:db0dc91f0231 441 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 442 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 443 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 444 icmpSum[0]=0;
nixnax 29:30de79d658f6 445 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 446 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 447 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 448 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 449 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 450
nixnax 16:cb0b80c24ba2 451 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 452 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 453 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 454 if (v0) {
nixnax 29:30de79d658f6 455 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 456 char ch = icmpData[i];
nixnax 29:30de79d658f6 457 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 458 debug("%c",ch);
nixnax 29:30de79d658f6 459 } else {
nixnax 64:677b9713a120 460 debug("_");
nixnax 29:30de79d658f6 461 }
nixnax 29:30de79d658f6 462 }
nixnax 64:677b9713a120 463 debug("\n");
nixnax 29:30de79d658f6 464 }
nixnax 93:9675adc36882 465 send_pppFrame(); // reply to the ping
nixnax 29:30de79d658f6 466
nixnax 12:db0dc91f0231 467 } else {
nixnax 29:30de79d658f6 468 if (v0) {
nixnax 42:4de44be70bfd 469 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 470 }
nixnax 11:f58998c24f0b 471 }
nixnax 11:f58998c24f0b 472 }
nixnax 11:f58998c24f0b 473
nixnax 29:30de79d658f6 474 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 475 {
nixnax 29:30de79d658f6 476 if (v0) {
nixnax 42:4de44be70bfd 477 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 478 }
nixnax 29:30de79d658f6 479 }
nixnax 11:f58998c24f0b 480
nixnax 29:30de79d658f6 481 void dumpHeaderIP ()
nixnax 29:30de79d658f6 482 {
nixnax 95:40af49390daf 483 if (v0) {
nixnax 95:40af49390daf 484 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 485 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 486 char * version = ipPkt; // top 4 bits
nixnax 95:40af49390daf 487 char * ihl = ipPkt; // bottom 4 bits
nixnax 95:40af49390daf 488 char * dscp = ipPkt+1; // top 6 bits
nixnax 95:40af49390daf 489 char * ecn = ipPkt+1; // lower 2 bits
nixnax 95:40af49390daf 490 char * pktLen = ipPkt+2; // 2 bytes
nixnax 95:40af49390daf 491 char * ident = ipPkt+4; // 2 bytes
nixnax 95:40af49390daf 492 char * flags = ipPkt+6; // 2 bits
nixnax 95:40af49390daf 493 char * ttl = ipPkt+8; // 1 byte
nixnax 95:40af49390daf 494 char * protocol = ipPkt+9; // 1 byte
nixnax 95:40af49390daf 495 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 496 #endif
nixnax 95:40af49390daf 497 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 95:40af49390daf 498 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 499
nixnax 55:43faae812be3 500 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 95:40af49390daf 501 int versionIP = (version[0]>>4)&0xf;
nixnax 95:40af49390daf 502 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 95:40af49390daf 503 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 95:40af49390daf 504 int ecnIP = ecn[0]&3;
nixnax 95:40af49390daf 505 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 95:40af49390daf 506 int identIP = (ident[0]<<8)|ident[1];
nixnax 95:40af49390daf 507 int flagsIP = flags[0]>>14&3;
nixnax 95:40af49390daf 508 int ttlIP = ttl[0];
nixnax 95:40af49390daf 509 int protocolIP = protocol[0];
nixnax 95:40af49390daf 510 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 511 #endif
nixnax 55:43faae812be3 512
nixnax 95:40af49390daf 513 char srcIP [16];
nixnax 95:40af49390daf 514 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 95:40af49390daf 515 char dstIP [16];
nixnax 95:40af49390daf 516 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 95:40af49390daf 517 debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 95:40af49390daf 518 debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 95:40af49390daf 519 }
nixnax 29:30de79d658f6 520 }
nixnax 26:11f4eb2663a7 521
nixnax 29:30de79d658f6 522 void dumpHeaderTCP()
nixnax 29:30de79d658f6 523 {
nixnax 83:cdcb81d1910f 524 if( v0 ) {
nixnax 81:9ede60e9a2c8 525 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 526 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 527 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 528 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 529 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 530 #endif
nixnax 81:9ede60e9a2c8 531 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 532 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 533 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 534 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 535 #endif
nixnax 81:9ede60e9a2c8 536 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 537
nixnax 81:9ede60e9a2c8 538 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 539 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 540 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 541
nixnax 81:9ede60e9a2c8 542 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 543 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 544 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 545 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 546 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 547 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 548 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 549 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 550 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 551 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 552 }
nixnax 29:30de79d658f6 553 }
nixnax 29:30de79d658f6 554
nixnax 68:0b74763ae67f 555 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 556 {
nixnax 67:a63e3486bcda 557 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 558 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 559 int contentLengthStart; // index where HTML starts
nixnax 93:9675adc36882 560 int xFetch, httpGetRoot; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 561
nixnax 98:3babad0d1bd4 562 ppp.httpPageCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 563
nixnax 98:3babad0d1bd4 564 httpGetRoot = strncmp(dataStart, "GET / HTTP/1.", 13); // found GET, respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 565 xFetch = strncmp(dataStart, "GET /x", 6); // found GET /x , respond to both HTTP/1.<anything>
nixnax 99:3f56162e703e 566 // for example, in linux, xFetch can be used as: echo GET /x | nc 172.10.10.2
nixnax 93:9675adc36882 567 if( (httpGetRoot==0) || (xFetch==0) ) {
nixnax 89:2c8dd0c2a426 568 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 569 } else {
nixnax 89:2c8dd0c2a426 570 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 571 }
nixnax 83:cdcb81d1910f 572 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 573 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 574 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 575 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 576 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 577 nHeader=n; // size of HTTP header
nixnax 93:9675adc36882 578 if( httpGetRoot == 0 ) {
nixnax 83:cdcb81d1910f 579 // this is where we insert our web page into the buffer
nixnax 93:9675adc36882 580 //n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 93:9675adc36882 581 memcpy(n+dataStart,rootWebPage,sizeof(rootWebPage));
nixnax 93:9675adc36882 582 n = n + sizeof(rootWebPage);
nixnax 85:53e57ff1cf05 583 } else {
nixnax 106:d14e6b597ca3 584 if (xFetch == 0) { // the request started with "GET /x"
nixnax 89:2c8dd0c2a426 585
nixnax 89:2c8dd0c2a426 586 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 89:2c8dd0c2a426 587 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 89:2c8dd0c2a426 588 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 106:d14e6b597ca3 589 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed-ppp-blinky</title>"); // html title (W3C.org required elements)
nixnax 98:3babad0d1bd4 590 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.httpPageCount); // body = the http frame count
nixnax 89:2c8dd0c2a426 591 #else
nixnax 98:3babad0d1bd4 592 #define BENCHMARK_USING_BROWSER_NO /* set to _YES if you want to use your browser as a benchmark tool of http fetches */
nixnax 98:3babad0d1bd4 593 #ifndef BENCHMARK_USING_BROWSER_NO
nixnax 98:3babad0d1bd4 594 // a small script that reloads the page after 10 ms - handy for benchmarking using your web browser
nixnax 98:3babad0d1bd4 595 n=n+sprintf(n+dataStart, "<script>setTimeout(function(){location.reload();},10);</script><body>%d</body>",ppp.httpPageCount);
nixnax 98:3babad0d1bd4 596 #else
nixnax 98:3babad0d1bd4 597 n=n+sprintf(n+dataStart,"%d",ppp.httpPageCount); // not valid html but fast, most browsers and curl are ok with it
nixnax 98:3babad0d1bd4 598 #endif
nixnax 89:2c8dd0c2a426 599 #endif
nixnax 89:2c8dd0c2a426 600
nixnax 89:2c8dd0c2a426 601 } else {
nixnax 89:2c8dd0c2a426 602 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 89:2c8dd0c2a426 603 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky-mbed</title>"); // html title (required element)
nixnax 89:2c8dd0c2a426 604 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 89:2c8dd0c2a426 605 }
nixnax 83:cdcb81d1910f 606 }
nixnax 87:9f5ac1fabd95 607 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 608 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 609
nixnax 83:cdcb81d1910f 610 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 611 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 612 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 613 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 614
nixnax 77:abf92baebb42 615 if (v2) {
nixnax 77:abf92baebb42 616 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 617 }
nixnax 67:a63e3486bcda 618 return n; // total byte size of our response
nixnax 67:a63e3486bcda 619 }
nixnax 67:a63e3486bcda 620
nixnax 98:3babad0d1bd4 621 // if not an http response we just report the number of bytes received
nixnax 98:3babad0d1bd4 622 // this is handy when you for example want to use netcat (nc.exe) to talk to PPP-Blinky
nixnax 98:3babad0d1bd4 623 int tcpResponse(char * dataStart, int len)
nixnax 98:3babad0d1bd4 624 {
nixnax 98:3babad0d1bd4 625 int n=0; // number of bytes we have printed so far
nixnax 98:3babad0d1bd4 626
nixnax 98:3babad0d1bd4 627 n=n+sprintf(n+dataStart,"Got %04d bytes.\n",len); // report the number of bytes received
nixnax 98:3babad0d1bd4 628 while( (n%4)!= 0) n=n+sprintf(n+dataStart,"*"); // insert spaces until n is exactly two away from a multiple of four
nixnax 98:3babad0d1bd4 629 if (v2) {
nixnax 98:3babad0d1bd4 630 debug("TCP response %d byes\n",n);
nixnax 98:3babad0d1bd4 631 }
nixnax 98:3babad0d1bd4 632 return n; // total byte size of our response
nixnax 98:3babad0d1bd4 633 }
nixnax 98:3babad0d1bd4 634
nixnax 29:30de79d658f6 635 void tcpHandler()
nixnax 29:30de79d658f6 636 {
nixnax 87:9f5ac1fabd95 637 // IP header
nixnax 87:9f5ac1fabd95 638
nixnax 26:11f4eb2663a7 639 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 640 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 641 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 642 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 643 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 644 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 645 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 646 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 647 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 648 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 649
nixnax 87:9f5ac1fabd95 650 // TCP header
nixnax 87:9f5ac1fabd95 651
nixnax 87:9f5ac1fabd95 652 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 653 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 654 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 655 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 656 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 657 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 658 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 659 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 660 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 661
nixnax 26:11f4eb2663a7 662 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 663 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 664 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 665
nixnax 87:9f5ac1fabd95 666 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 667 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 668 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 669
nixnax 85:53e57ff1cf05 670 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 671 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 672
nixnax 85:53e57ff1cf05 673 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 674 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 675
nixnax 29:30de79d658f6 676 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 677 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 678 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 679 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 680 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 681
nixnax 87:9f5ac1fabd95 682 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 683 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 684
nixnax 87:9f5ac1fabd95 685 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 686 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 687 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 688 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 689 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 690 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 691
nixnax 35:e7068df4d971 692 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 693 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 694 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 695
nixnax 97:bdf885e146dc 696 windowsizetcp[0]=2; // tco window size = 700
nixnax 97:bdf885e146dc 697 windowsizetcp[1]=0xbc; // tcp windows size = 700
nixnax 38:ab582987926e 698
nixnax 93:9675adc36882 699 int doFin = 0; // flag to see if we have to send an extra FIN message to shut down the link
nixnax 93:9675adc36882 700
nixnax 106:d14e6b597ca3 701 // A sparse TCP flag interpreter that implements stateless TCP connections
nixnax 77:abf92baebb42 702
nixnax 69:23f560087c16 703 switch ( flagsTCP ) {
nixnax 69:23f560087c16 704 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 705 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 706 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 707 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 708 break;
nixnax 77:abf92baebb42 709 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 98:3babad0d1bd4 710 if ( strncmp(tcpDataIn, "GET /", 5) == 0) { // check for an http GET command
nixnax 98:3babad0d1bd4 711 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing this TCP connection
nixnax 87:9f5ac1fabd95 712 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 98:3babad0d1bd4 713 } else {
nixnax 106:d14e6b597ca3 714 dataLen = tcpResponse(tcpDataOut,tcpDataSize); // not a web request, send a packet reporting number of received bytes
nixnax 69:23f560087c16 715 }
nixnax 69:23f560087c16 716 break;
nixnax 98:3babad0d1bd4 717 case TCP_FLAG_FIN | TCP_FLAG_PSH | TCP_FLAG_ACK:
nixnax 69:23f560087c16 718 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 93:9675adc36882 719 case TCP_FLAG_RST:
nixnax 85:53e57ff1cf05 720 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 721 break;
nixnax 98:3babad0d1bd4 722 case TCP_FLAG_FIN:
nixnax 98:3babad0d1bd4 723 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // set the FIN flag to start closing the connection
nixnax 98:3babad0d1bd4 724 break;
nixnax 77:abf92baebb42 725 default:
nixnax 69:23f560087c16 726 return; // ignore remaining packets
nixnax 93:9675adc36882 727 } // switch
nixnax 77:abf92baebb42 728
nixnax 69:23f560087c16 729 // The TCP flag handling is now done
nixnax 105:45001195b325 730 // first we swap source and destination TCP addresses and insert the new ack and seq numbers
nixnax 95:40af49390daf 731
nixnax 65:23b17c43aa0f 732 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 733 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 734 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 735 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 736
nixnax 60:2b770949c911 737 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 738 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 739 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 95:40af49390daf 740
nixnax 93:9675adc36882 741 sendTCP:
nixnax 106:d14e6b597ca3 742
nixnax 85:53e57ff1cf05 743 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 744 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 745 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 746 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 747
nixnax 85:53e57ff1cf05 748 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 749 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 750 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 751 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 752
nixnax 93:9675adc36882 753 flagbitstcp[1] = flagsOut; // update the TCP flags
nixnax 93:9675adc36882 754
nixnax 93:9675adc36882 755 // increment the ip ident number
nixnax 93:9675adc36882 756 ppp.ident++; // get next ident number for our packet
nixnax 93:9675adc36882 757 ident[0] = ppp.ident>>8;
nixnax 93:9675adc36882 758 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 93:9675adc36882 759
nixnax 106:d14e6b597ca3 760 // Now we recalculate all the header sizes
nixnax 38:ab582987926e 761 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 762 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 763 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 764 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 765 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 766
nixnax 38:ab582987926e 767 // the header is all set up, now do the IP and TCP checksums
nixnax 61:b3c1a04efd0a 768 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 769 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 770 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 771
nixnax 64:677b9713a120 772 // 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 773 // 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 774
nixnax 87:9f5ac1fabd95 775 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 776 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 777 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 778 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 779 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 780 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 781 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 782
nixnax 61:b3c1a04efd0a 783 // pseudo-header built, now we can calculate TCP checksum
nixnax 29:30de79d658f6 784 checksumtcp[0]=0;
nixnax 29:30de79d658f6 785 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 786 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 787 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 788 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 789 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 95:40af49390daf 790
nixnax 93:9675adc36882 791 send_pppFrame(); // All preparation complete - send the TCP response
nixnax 60:2b770949c911 792
nixnax 93:9675adc36882 793 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 794 doFin=0;
nixnax 93:9675adc36882 795 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // tell them we are also finished
nixnax 93:9675adc36882 796 goto sendTCP; // send our final packet for this conversation.
nixnax 93:9675adc36882 797 }
nixnax 83:cdcb81d1910f 798 dumpHeaderIP();
nixnax 95:40af49390daf 799 dumpHeaderTCP();
nixnax 29:30de79d658f6 800 }
nixnax 26:11f4eb2663a7 801
nixnax 29:30de79d658f6 802 void dumpDataTCP()
nixnax 29:30de79d658f6 803 {
nixnax 26:11f4eb2663a7 804 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 805 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 806 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 807 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 808 if (v1) {
nixnax 42:4de44be70bfd 809 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 810 }
nixnax 29:30de79d658f6 811 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 812 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 813 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 814 }
nixnax 29:30de79d658f6 815 }
nixnax 26:11f4eb2663a7 816
nixnax 29:30de79d658f6 817 void TCPpacket()
nixnax 29:30de79d658f6 818 {
nixnax 83:cdcb81d1910f 819 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 820 dumpHeaderTCP();
nixnax 77:abf92baebb42 821 if (v2) {
nixnax 77:abf92baebb42 822 dumpDataTCP();
nixnax 77:abf92baebb42 823 }
nixnax 26:11f4eb2663a7 824 tcpHandler();
nixnax 11:f58998c24f0b 825 }
nixnax 11:f58998c24f0b 826
nixnax 29:30de79d658f6 827 void otherProtocol()
nixnax 29:30de79d658f6 828 {
nixnax 64:677b9713a120 829 debug("Other IP protocol");
nixnax 29:30de79d658f6 830 }
nixnax 26:11f4eb2663a7 831
nixnax 29:30de79d658f6 832 void IPframe()
nixnax 29:30de79d658f6 833 {
nixnax 10:74f8233f72c0 834 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 835 switch (protocol) {
nixnax 29:30de79d658f6 836 case 1:
nixnax 29:30de79d658f6 837 ICMPpacket();
nixnax 29:30de79d658f6 838 break;
nixnax 29:30de79d658f6 839 case 2:
nixnax 29:30de79d658f6 840 IGMPpacket();
nixnax 29:30de79d658f6 841 break;
nixnax 29:30de79d658f6 842 case 17:
nixnax 29:30de79d658f6 843 UDPpacket();
nixnax 29:30de79d658f6 844 break;
nixnax 29:30de79d658f6 845 case 6:
nixnax 29:30de79d658f6 846 TCPpacket();
nixnax 29:30de79d658f6 847 break;
nixnax 29:30de79d658f6 848 default:
nixnax 29:30de79d658f6 849 otherProtocol();
nixnax 29:30de79d658f6 850 }
nixnax 29:30de79d658f6 851 }
nixnax 9:0992486d4a30 852
nixnax 29:30de79d658f6 853 void LCPconfReq()
nixnax 29:30de79d658f6 854 {
nixnax 64:677b9713a120 855 debug("LCP Config ");
nixnax 9:0992486d4a30 856 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 857 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 858 debug("Reject\n");
nixnax 93:9675adc36882 859 send_pppFrame();
nixnax 9:0992486d4a30 860 } else {
nixnax 9:0992486d4a30 861 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 862 debug("Ack\n");
nixnax 93:9675adc36882 863 send_pppFrame();
nixnax 64:677b9713a120 864 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 865 ppp.pkt.buf[4]=1; // request no options
nixnax 93:9675adc36882 866 send_pppFrame();
nixnax 9:0992486d4a30 867 }
nixnax 9:0992486d4a30 868 }
nixnax 9:0992486d4a30 869
nixnax 29:30de79d658f6 870 void LCPconfAck()
nixnax 29:30de79d658f6 871 {
nixnax 64:677b9713a120 872 debug("LCP Ack\n");
nixnax 29:30de79d658f6 873 }
nixnax 9:0992486d4a30 874
nixnax 29:30de79d658f6 875 void LCPend()
nixnax 29:30de79d658f6 876 {
nixnax 29:30de79d658f6 877 ppp.pkt.buf[4]=6;
nixnax 93:9675adc36882 878 send_pppFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 879 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 880 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 881 debug("LCP End\n");
nixnax 9:0992486d4a30 882 }
nixnax 9:0992486d4a30 883
nixnax 29:30de79d658f6 884 void LCPother()
nixnax 29:30de79d658f6 885 {
nixnax 64:677b9713a120 886 debug("LCP Other\n");
nixnax 95:40af49390daf 887 dumpPPPFrame();
nixnax 29:30de79d658f6 888 }
nixnax 29:30de79d658f6 889
nixnax 29:30de79d658f6 890 void LCPframe()
nixnax 29:30de79d658f6 891 {
nixnax 29:30de79d658f6 892 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 893 switch (code) {
nixnax 29:30de79d658f6 894 case 1:
nixnax 29:30de79d658f6 895 LCPconfReq();
nixnax 29:30de79d658f6 896 break; // config request
nixnax 29:30de79d658f6 897 case 2:
nixnax 29:30de79d658f6 898 LCPconfAck();
nixnax 29:30de79d658f6 899 break; // config ack
nixnax 29:30de79d658f6 900 case 5:
nixnax 29:30de79d658f6 901 LCPend();
nixnax 29:30de79d658f6 902 break; // end connection
nixnax 29:30de79d658f6 903 default:
nixnax 29:30de79d658f6 904 LCPother();
nixnax 29:30de79d658f6 905 }
nixnax 9:0992486d4a30 906 }
nixnax 9:0992486d4a30 907
nixnax 29:30de79d658f6 908 void discardedFrame()
nixnax 29:30de79d658f6 909 {
nixnax 29:30de79d658f6 910 if (v0) {
nixnax 71:965619fedb3a 911 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 912 }
nixnax 9:0992486d4a30 913 }
nixnax 9:0992486d4a30 914
nixnax 29:30de79d658f6 915 void determinePacketType()
nixnax 29:30de79d658f6 916 {
nixnax 29:30de79d658f6 917 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 918 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 919 return;
nixnax 29:30de79d658f6 920 }
nixnax 29:30de79d658f6 921 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 922 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 923 return;
nixnax 29:30de79d658f6 924 }
nixnax 29:30de79d658f6 925 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 926 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 927 return;
nixnax 29:30de79d658f6 928 }
nixnax 9:0992486d4a30 929 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 930 switch (packetType) {
nixnax 29:30de79d658f6 931 case 0xc0:
nixnax 29:30de79d658f6 932 LCPframe();
nixnax 29:30de79d658f6 933 break; // link control
nixnax 29:30de79d658f6 934 case 0x80:
nixnax 29:30de79d658f6 935 IPCPframe();
nixnax 29:30de79d658f6 936 break; // IP control
nixnax 29:30de79d658f6 937 case 0x00:
nixnax 29:30de79d658f6 938 IPframe();
nixnax 29:30de79d658f6 939 break; // IP itself
nixnax 29:30de79d658f6 940 default:
nixnax 29:30de79d658f6 941 discardedFrame();
nixnax 9:0992486d4a30 942 }
nixnax 29:30de79d658f6 943 }
nixnax 9:0992486d4a30 944
nixnax 50:ad4e7c3c88e5 945 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 946 {
nixnax 85:53e57ff1cf05 947 while(1) {
nixnax 93:9675adc36882 948 fillbuf(); // handle received characters
nixnax 81:9ede60e9a2c8 949 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 950 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 951 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 952 if (rx==FRAME_7E) {
nixnax 106:d14e6b597ca3 953 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 107:5fe806713d49 954
nixnax 106:d14e6b597ca3 955 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 107:5fe806713d49 956
nixnax 106:d14e6b597ca3 957 ppp.rx.rtail = ppp.rx.tail;
nixnax 106:d14e6b597ca3 958 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 106:d14e6b597ca3 959 break;
nixnax 50:ad4e7c3c88e5 960 }
nixnax 50:ad4e7c3c88e5 961 }
nixnax 85:53e57ff1cf05 962 }
nixnax 50:ad4e7c3c88e5 963 }
nixnax 50:ad4e7c3c88e5 964
nixnax 29:30de79d658f6 965 void scanForConnectString()
nixnax 29:30de79d658f6 966 {
nixnax 81:9ede60e9a2c8 967 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 968 fillbuf();
nixnax 81:9ede60e9a2c8 969 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 106:d14e6b597ca3 970 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENT" );
nixnax 107:5fe806713d49 971 if (found1 != NULL) {
nixnax 107:5fe806713d49 972 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 107:5fe806713d49 973 led1Toggle();
nixnax 107:5fe806713d49 974 if (v0) debug("Found connect string \"CLIENT\", sent \"CLIENTSERVER\"\n");
nixnax 107:5fe806713d49 975 pc.puts("CLIENTSERVER");
nixnax 107:5fe806713d49 976 ppp.online=1; // we are connected, so we can stop looking for the connect string
nixnax 9:0992486d4a30 977 }
nixnax 9:0992486d4a30 978 }
nixnax 103:4f5512dd11cf 979 }
nixnax 81:9ede60e9a2c8 980
nixnax 9:0992486d4a30 981
nixnax 107:5fe806713d49 982
nixnax 107:5fe806713d49 983
nixnax 107:5fe806713d49 984
nixnax 107:5fe806713d49 985
nixnax 0:2cf4880c312a 986 int main()
nixnax 0:2cf4880c312a 987 {
nixnax 14:c65831c25aaa 988 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 989 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 990 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 991 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 992 #endif
nixnax 9:0992486d4a30 993 pppInitStruct(); // initialize all the PPP properties
nixnax 0:2cf4880c312a 994 while(1) {
nixnax 51:a86d56844324 995 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 996 while(ppp.online) {
nixnax 81:9ede60e9a2c8 997 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 998 }
nixnax 7:ab147f5e97ac 999 }
nixnax 105:45001195b325 1000 }