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@87:9f5ac1fabd95, 2017-07-21 (annotated)

Committer:
nixnax
Date:
Fri Jul 21 00:35:24 2017 +0000
Revision:
87:9f5ac1fabd95
Parent:
85:53e57ff1cf05
Child:
88:b4a71242837c
Changed TCP flag handling.; All TCP headers to 20 bytes.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 81:9ede60e9a2c8 1 // PPP-Blinky - "My Internet Of Thing"
nixnax 0:2cf4880c312a 2
nixnax 72:ad3d12753acf 3 // A Tiny Webserver Using Windows XP/7/8/10 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 81:9ede60e9a2c8 7 // Copyright 2016 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 44:d0c61ae49ea5 20 // Wireshark - can't monitor Dial-Up network packets on windows, but useful - can import our dumpFrame routine's hex output
nixnax 29:30de79d658f6 21 // Microsoft network monitor - real-time monitoring of all our packets
nixnax 29:30de79d658f6 22 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 29:30de79d658f6 23 // 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 41:e58a5a09f411 24 // The curl.exe program in Windows Powershell - use it like this to stress test the webserver: while (1) { curl 172.10.10.1 }
nixnax 29:30de79d658f6 25 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 41:e58a5a09f411 26 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 41:e58a5a09f411 27
nixnax 81:9ede60e9a2c8 28 #include "mbed.h"
nixnax 66:f005b9fdf4d1 29
nixnax 66:f005b9fdf4d1 30 // The #define below enables/disables a SECOND (optional) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 31 // 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 82:051f77f7dd72 32 #define SERIAL_PORT_MONITOR_NO /* or change to SERIAL_PORT_MONITOR_YES */
nixnax 0:2cf4880c312a 33
nixnax 41:e58a5a09f411 34 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 35
nixnax 85:53e57ff1cf05 36 // here we define the debug serial port for the various target boards
nixnax 85:53e57ff1cf05 37 // add yours if it's not in here
nixnax 85:53e57ff1cf05 38 #if TARGET_LPC1768
nixnax 85:53e57ff1cf05 39 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 85:53e57ff1cf05 40 #elif TARGET_NUCLEO_F446RE
nixnax 85:53e57ff1cf05 41 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 42 #elif TARGET_NUCLEO_L152RE
nixnax 85:53e57ff1cf05 43 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 44 #else
nixnax 85:53e57ff1cf05 45 #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 46 #endif
nixnax 85:53e57ff1cf05 47
nixnax 85:53e57ff1cf05 48
nixnax 42:4de44be70bfd 49 #define debug(x...) xx.printf (x)
nixnax 41:e58a5a09f411 50 #else
nixnax 42:4de44be70bfd 51 #define debug(x...) {}
nixnax 41:e58a5a09f411 52 #endif
nixnax 41:e58a5a09f411 53
nixnax 66:f005b9fdf4d1 54 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 83:cdcb81d1910f 55 #define v0 1
nixnax 66:f005b9fdf4d1 56 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 57 #define v1 0
nixnax 77:abf92baebb42 58 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 77:abf92baebb42 59 #define v2 0
nixnax 29:30de79d658f6 60
nixnax 66:f005b9fdf4d1 61 // this is the webpage we serve when we get an HTTP request
nixnax 72:ad3d12753acf 62 // keep size under 900 bytes to fit into a single frame
nixnax 66:f005b9fdf4d1 63 const static char ourWebPage[] = "\
nixnax 66:f005b9fdf4d1 64 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 65 <html>\
nixnax 66:f005b9fdf4d1 66 <head>\
nixnax 66:f005b9fdf4d1 67 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 68 <script>\
nixnax 66:f005b9fdf4d1 69 window.onload=function(){\
nixnax 66:f005b9fdf4d1 70 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 71 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 72 </script>\
nixnax 66:f005b9fdf4d1 73 </head>\
nixnax 66:f005b9fdf4d1 74 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 75 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 76 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 77 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 78 </body>\
nixnax 69:23f560087c16 79 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 80
nixnax 69:23f560087c16 81
nixnax 66:f005b9fdf4d1 82
nixnax 73:2f56ec87dbe9 83 // 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 84 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 85 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 86 // See instructions at the top.
nixnax 73:2f56ec87dbe9 87 // 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 88 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 89
nixnax 29:30de79d658f6 90 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 91
nixnax 66:f005b9fdf4d1 92 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 93 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 94
nixnax 29:30de79d658f6 95 // the serial port receive buffer and packet buffer
nixnax 0:2cf4880c312a 96
nixnax 29:30de79d658f6 97 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 98 struct pppType {
nixnax 38:ab582987926e 99 int online; // we hunt for a PPP connection if this is zero
nixnax 87:9f5ac1fabd95 100 unsigned int ident; // our IP ident value
nixnax 38:ab582987926e 101 unsigned int seq; // our TCP sequence number
nixnax 38:ab582987926e 102 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 103 int ledState; // state of LED1
nixnax 87:9f5ac1fabd95 104 int httpFrameCount;
nixnax 4:a469050d5b80 105 struct {
nixnax 81:9ede60e9a2c8 106 #define RXBUFLEN (1<<14)
nixnax 85:53e57ff1cf05 107 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 72:ad3d12753acf 108 //char * buf;
nixnax 29:30de79d658f6 109 volatile int head;
nixnax 29:30de79d658f6 110 volatile int tail;
nixnax 81:9ede60e9a2c8 111 volatile int buflevel;
nixnax 38:ab582987926e 112 } rx; // serial port objects
nixnax 4:a469050d5b80 113 struct {
nixnax 38:ab582987926e 114 int len; // number of bytes in buffer
nixnax 38:ab582987926e 115 int crc; // PPP CRC (frame check)
nixnax 72:ad3d12753acf 116 //char * buf; // the actual buffer
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 81:9ede60e9a2c8 123 int frameFound; // we have found at least one start of frame already
nixnax 50:ad4e7c3c88e5 124 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 125 };
nixnax 31:e000c1b9c565 126
nixnax 29:30de79d658f6 127 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 128
nixnax 60:2b770949c911 129 // Initialize our globals
nixnax 29:30de79d658f6 130 void pppInitStruct()
nixnax 29:30de79d658f6 131 {
nixnax 81:9ede60e9a2c8 132 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 133 ppp.online=0;
nixnax 29:30de79d658f6 134 ppp.rx.tail=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.frameFound=0;
nixnax 81:9ede60e9a2c8 141 ppp.hdlc.frameStartIndex=0;
nixnax 87:9f5ac1fabd95 142 ppp.httpFrameCount=0;
nixnax 29:30de79d658f6 143 }
nixnax 26:11f4eb2663a7 144
nixnax 43:aa57db08995d 145 void led1Toggle()
nixnax 43:aa57db08995d 146 {
nixnax 43:aa57db08995d 147 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 43:aa57db08995d 148 led1 = ppp.ledState;
nixnax 43:aa57db08995d 149 }
nixnax 43:aa57db08995d 150
nixnax 29:30de79d658f6 151 void crcReset()
nixnax 29:30de79d658f6 152 {
nixnax 29:30de79d658f6 153 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 154 }
nixnax 4:a469050d5b80 155
nixnax 29:30de79d658f6 156 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 157 {
nixnax 29:30de79d658f6 158 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 159 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 160 x>>=1;
nixnax 29:30de79d658f6 161 }
nixnax 29:30de79d658f6 162 }
nixnax 29:30de79d658f6 163
nixnax 29:30de79d658f6 164 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 165 {
nixnax 31:e000c1b9c565 166 crcReset();
nixnax 31:e000c1b9c565 167 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 168 return ppp.crc;
nixnax 29:30de79d658f6 169 }
nixnax 0:2cf4880c312a 170
nixnax 85:53e57ff1cf05 171
nixnax 85:53e57ff1cf05 172 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 173 void fillbuf()
nixnax 0:2cf4880c312a 174 {
nixnax 85:53e57ff1cf05 175 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 176 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 83:cdcb81d1910f 177 if ( hd == ppp.rx.tail ) {
nixnax 85:53e57ff1cf05 178 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 179 return;
nixnax 83:cdcb81d1910f 180 }
nixnax 17:4918c893d802 181 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 182 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 183 ppp.rx.buflevel++;
nixnax 15:b0154c910143 184 }
nixnax 0:2cf4880c312a 185 }
nixnax 0:2cf4880c312a 186
nixnax 85:53e57ff1cf05 187 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 188 {
nixnax 43:aa57db08995d 189 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 190 return emptyStatus;
nixnax 0:2cf4880c312a 191 }
nixnax 0:2cf4880c312a 192
nixnax 85:53e57ff1cf05 193 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 194 {
nixnax 63:9253b0e1b7d8 195 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 196 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 197 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 198 return x;
nixnax 0:2cf4880c312a 199 }
nixnax 0:2cf4880c312a 200
nixnax 50:ad4e7c3c88e5 201 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 202 {
nixnax 38:ab582987926e 203 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 204 if(start==end) {
nixnax 29:30de79d658f6 205 return;
nixnax 29:30de79d658f6 206 }
nixnax 9:0992486d4a30 207 crcReset();
nixnax 9:0992486d4a30 208 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 209 ppp.pkt.len=0;
nixnax 9:0992486d4a30 210 int unstuff=0;
nixnax 17:4918c893d802 211 int idx = start;
nixnax 17:4918c893d802 212 while(1) {
nixnax 9:0992486d4a30 213 if (unstuff==0) {
nixnax 72:ad3d12753acf 214 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 215 else {
nixnax 72:ad3d12753acf 216 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 217 ppp.pkt.len++;
nixnax 29:30de79d658f6 218 dest++;
nixnax 72:ad3d12753acf 219 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 220 }
nixnax 66:f005b9fdf4d1 221 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 222 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 223 ppp.pkt.len++;
nixnax 29:30de79d658f6 224 dest++;
nixnax 72:ad3d12753acf 225 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 226 unstuff=0;
nixnax 9:0992486d4a30 227 }
nixnax 81:9ede60e9a2c8 228 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 229 if (idx == end) break;
nixnax 9:0992486d4a30 230 }
nixnax 29:30de79d658f6 231 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 232 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 233 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 234 determinePacketType();
nixnax 29:30de79d658f6 235 } else if (v0) {
nixnax 85:53e57ff1cf05 236 // 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 237 }
nixnax 9:0992486d4a30 238 }
nixnax 9:0992486d4a30 239
nixnax 38:ab582987926e 240 // Note - the hex output of dumpFrame() can be imported into WireShark
nixnax 38:ab582987926e 241 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 38:ab582987926e 242 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 29:30de79d658f6 243 void dumpFrame()
nixnax 29:30de79d658f6 244 {
nixnax 42:4de44be70bfd 245 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 42:4de44be70bfd 246 debug(" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len);
nixnax 16:cb0b80c24ba2 247 }
nixnax 16:cb0b80c24ba2 248
nixnax 29:30de79d658f6 249 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 250 {
nixnax 29:30de79d658f6 251 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 252 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 253 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 254 } else {
nixnax 29:30de79d658f6 255 pc.putc(ch);
nixnax 29:30de79d658f6 256 }
nixnax 11:f58998c24f0b 257 }
nixnax 9:0992486d4a30 258
nixnax 85:53e57ff1cf05 259 void sendFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 260 {
nixnax 17:4918c893d802 261 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 262 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 263 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 264 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 29:30de79d658f6 265 for(int i=0; i<ppp.pkt.len; i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 266 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 267 }
nixnax 9:0992486d4a30 268
nixnax 66:f005b9fdf4d1 269 void ipConfigRequestHandler()
nixnax 29:30de79d658f6 270 {
nixnax 64:677b9713a120 271 debug("IPCP Conf ");
nixnax 9:0992486d4a30 272 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 66:f005b9fdf4d1 273 debug("Rej\n"); // reject any options that are requested
nixnax 9:0992486d4a30 274 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 275 sendFrame();
nixnax 9:0992486d4a30 276 } else {
nixnax 64:677b9713a120 277 debug("Ack\n");
nixnax 9:0992486d4a30 278 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 279 sendFrame(); // acknowledge
nixnax 64:677b9713a120 280 debug("IPCP Ask\n");
nixnax 9:0992486d4a30 281 // send our own request now
nixnax 12:db0dc91f0231 282 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 283 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 284 sendFrame(); // this is our request
nixnax 9:0992486d4a30 285 }
nixnax 9:0992486d4a30 286 }
nixnax 9:0992486d4a30 287
nixnax 29:30de79d658f6 288 void ipAckHandler()
nixnax 29:30de79d658f6 289 {
nixnax 64:677b9713a120 290 debug("IPCP Grant\n");
nixnax 29:30de79d658f6 291 }
nixnax 9:0992486d4a30 292
nixnax 29:30de79d658f6 293 void ipNackHandler()
nixnax 29:30de79d658f6 294 {
nixnax 64:677b9713a120 295 debug("IPCP Nack\n");
nixnax 29:30de79d658f6 296 }
nixnax 9:0992486d4a30 297
nixnax 29:30de79d658f6 298 void ipDefaultHandler()
nixnax 29:30de79d658f6 299 {
nixnax 64:677b9713a120 300 debug("IPCP Other\n");
nixnax 29:30de79d658f6 301 }
nixnax 29:30de79d658f6 302
nixnax 29:30de79d658f6 303 void IPCPframe()
nixnax 29:30de79d658f6 304 {
nixnax 9:0992486d4a30 305 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 306 switch (code) {
nixnax 29:30de79d658f6 307 case 1:
nixnax 66:f005b9fdf4d1 308 ipConfigRequestHandler();
nixnax 29:30de79d658f6 309 break;
nixnax 29:30de79d658f6 310 case 2:
nixnax 29:30de79d658f6 311 ipAckHandler();
nixnax 29:30de79d658f6 312 break;
nixnax 29:30de79d658f6 313 case 3:
nixnax 29:30de79d658f6 314 ipNackHandler();
nixnax 29:30de79d658f6 315 break;
nixnax 29:30de79d658f6 316 default:
nixnax 29:30de79d658f6 317 ipDefaultHandler();
nixnax 9:0992486d4a30 318 }
nixnax 29:30de79d658f6 319 }
nixnax 9:0992486d4a30 320
nixnax 29:30de79d658f6 321 void UDPpacket()
nixnax 29:30de79d658f6 322 {
nixnax 12:db0dc91f0231 323 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 324 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 325 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 326 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 327 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 328 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 329 #endif
nixnax 12:db0dc91f0231 330 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 331 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 332 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 333 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 334 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 335 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 336 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 337 #endif
nixnax 29:30de79d658f6 338 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 339 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 340 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 341 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 342 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 343 int printSize = udpLength;
nixnax 29:30de79d658f6 344 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 345 if (v1) {
nixnax 29:30de79d658f6 346 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 347 char ch = udpInf[i];
nixnax 29:30de79d658f6 348 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 349 debug("%c", ch);
nixnax 29:30de79d658f6 350 } else {
nixnax 64:677b9713a120 351 debug("_");
nixnax 29:30de79d658f6 352 }
nixnax 29:30de79d658f6 353 }
nixnax 29:30de79d658f6 354 }
nixnax 83:cdcb81d1910f 355 if (v0) debug("\n");
nixnax 12:db0dc91f0231 356 }
nixnax 11:f58998c24f0b 357
nixnax 76:00e208cceb8b 358 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 359 {
nixnax 77:abf92baebb42 360
nixnax 75:0d513869231f 361 unsigned int sum=0;
nixnax 76:00e208cceb8b 362 unsigned char placeHolder;
nixnax 29:30de79d658f6 363 if (len&1) {
nixnax 76:00e208cceb8b 364 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 365 ptr[len]=0;
nixnax 29:30de79d658f6 366 }
nixnax 29:30de79d658f6 367 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 368 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 369 ptr++;
nixnax 76:00e208cceb8b 370 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 371 ptr++;
nixnax 76:00e208cceb8b 372 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 373 sum = sum + val;
nixnax 11:f58998c24f0b 374 }
nixnax 29:30de79d658f6 375 if (len&1) {
nixnax 76:00e208cceb8b 376 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 377 }
nixnax 76:00e208cceb8b 378 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 379 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 380 return ~sum;
nixnax 29:30de79d658f6 381 }
nixnax 11:f58998c24f0b 382
nixnax 29:30de79d658f6 383 void headerCheckSum()
nixnax 29:30de79d658f6 384 {
nixnax 11:f58998c24f0b 385 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 386 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 387 int sum=0;
nixnax 11:f58998c24f0b 388
nixnax 29:30de79d658f6 389 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 390 int hi = *ptr;
nixnax 29:30de79d658f6 391 ptr++;
nixnax 29:30de79d658f6 392 int lo = *ptr;
nixnax 29:30de79d658f6 393 ptr++;
nixnax 11:f58998c24f0b 394 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 395 sum = sum + val;
nixnax 11:f58998c24f0b 396 }
nixnax 11:f58998c24f0b 397 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 398 sum = ~sum;
nixnax 11:f58998c24f0b 399 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 400 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 401 }
nixnax 9:0992486d4a30 402
nixnax 29:30de79d658f6 403 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 404 {
nixnax 12:db0dc91f0231 405 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 406 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 407 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 408 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 409 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 410 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 411 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 412 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 413 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 414 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 415 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 416 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 417 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 418 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 419 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 420 #endif
nixnax 81:9ede60e9a2c8 421 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 422 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 423 char src[4];
nixnax 29:30de79d658f6 424 char dst[4];
nixnax 12:db0dc91f0231 425 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 426 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 427 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 428 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 429 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 430 chkSum[0]=0;
nixnax 29:30de79d658f6 431 chkSum[1]=0;
nixnax 12:db0dc91f0231 432 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 433 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 434 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 435 icmpSum[0]=0;
nixnax 29:30de79d658f6 436 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 437 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 438 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 439 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 440 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 441
nixnax 16:cb0b80c24ba2 442 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 443 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 444 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 445 if (v0) {
nixnax 29:30de79d658f6 446 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 447 char ch = icmpData[i];
nixnax 29:30de79d658f6 448 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 449 debug("%c",ch);
nixnax 29:30de79d658f6 450 } else {
nixnax 64:677b9713a120 451 debug("_");
nixnax 29:30de79d658f6 452 }
nixnax 29:30de79d658f6 453 }
nixnax 64:677b9713a120 454 debug("\n");
nixnax 29:30de79d658f6 455 }
nixnax 15:b0154c910143 456 sendFrame(); // reply to the ping
nixnax 29:30de79d658f6 457
nixnax 12:db0dc91f0231 458 } else {
nixnax 29:30de79d658f6 459 if (v0) {
nixnax 42:4de44be70bfd 460 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 461 }
nixnax 11:f58998c24f0b 462 }
nixnax 11:f58998c24f0b 463 }
nixnax 11:f58998c24f0b 464
nixnax 29:30de79d658f6 465 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 466 {
nixnax 29:30de79d658f6 467 if (v0) {
nixnax 42:4de44be70bfd 468 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 469 }
nixnax 29:30de79d658f6 470 }
nixnax 11:f58998c24f0b 471
nixnax 29:30de79d658f6 472 void dumpHeaderIP ()
nixnax 29:30de79d658f6 473 {
nixnax 26:11f4eb2663a7 474 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 475 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 26:11f4eb2663a7 476 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 477 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 478 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 479 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 480 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 481 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 482 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 483 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 484 char * protocol = ipPkt+9; // 1 byte
nixnax 77:abf92baebb42 485 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 486 #endif
nixnax 26:11f4eb2663a7 487 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 488 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 489
nixnax 55:43faae812be3 490 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 29:30de79d658f6 491 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 492 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 493 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 494 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 495 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 496 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 497 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 498 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 499 int protocolIP = protocol[0];
nixnax 76:00e208cceb8b 500 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 501 #endif
nixnax 55:43faae812be3 502
nixnax 29:30de79d658f6 503 char srcIP [16];
nixnax 29:30de79d658f6 504 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 85:53e57ff1cf05 505 fillbuf();
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 85:53e57ff1cf05 508 fillbuf();
nixnax 82:051f77f7dd72 509 if (v0) debug("IP %s %s v%d h%d d%d e%d L%03d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength);
nixnax 85:53e57ff1cf05 510 fillbuf();
nixnax 42:4de44be70bfd 511 if (v0) debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 29:30de79d658f6 512 }
nixnax 26:11f4eb2663a7 513
nixnax 29:30de79d658f6 514 void dumpHeaderTCP()
nixnax 29:30de79d658f6 515 {
nixnax 83:cdcb81d1910f 516 if( v0 ) {
nixnax 81:9ede60e9a2c8 517
nixnax 81:9ede60e9a2c8 518 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 519 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 520 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 521 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 522 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 523 #endif
nixnax 81:9ede60e9a2c8 524 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 525 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 526 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 527 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 528 #endif
nixnax 81:9ede60e9a2c8 529 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 530
nixnax 81:9ede60e9a2c8 531 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 532 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 533 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 534
nixnax 81:9ede60e9a2c8 535 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 536 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 537 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 538 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 539 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 540 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 541 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 542 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 543 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 544 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 545 }
nixnax 29:30de79d658f6 546 }
nixnax 29:30de79d658f6 547
nixnax 68:0b74763ae67f 548 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 549 {
nixnax 67:a63e3486bcda 550 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 551 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 552 int contentLengthStart; // index where HTML starts
nixnax 85:53e57ff1cf05 553
nixnax 87:9f5ac1fabd95 554 ppp.httpFrameCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 555
nixnax 84:456e73151f11 556 int rootFetch = strncmp(dataStart, "GET / HTTP/1.1", 14);
nixnax 77:abf92baebb42 557
nixnax 84:456e73151f11 558 if( rootFetch == 0 ) {
nixnax 67:a63e3486bcda 559 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: PPP-Blinky\r\n"); // http header
nixnax 83:cdcb81d1910f 560 } else {
nixnax 67:a63e3486bcda 561 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: PPP-Blinky\r\n"); // http header
nixnax 83:cdcb81d1910f 562 }
nixnax 85:53e57ff1cf05 563
nixnax 83:cdcb81d1910f 564 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 565 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 566 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 567 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 568 n=n+sprintf(n+dataStart,"Content-Type: text/html; charset=us-ascii\r\n\r\n"); // http header must end with empty line (\r\n)
nixnax 83:cdcb81d1910f 569 nHeader=n; // size of HTTP header
nixnax 67:a63e3486bcda 570
nixnax 84:456e73151f11 571 if( rootFetch == 0 ) {
nixnax 83:cdcb81d1910f 572 // this is where we insert our web page into the buffer
nixnax 83:cdcb81d1910f 573 n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 85:53e57ff1cf05 574 } else {
nixnax 87:9f5ac1fabd95 575 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 87:9f5ac1fabd95 576 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky</title>"); // html start
nixnax 87:9f5ac1fabd95 577 n=n+sprintf(n+dataStart,"<body>%06d</body>",ppp.httpFrameCount); // body = the http frame count
nixnax 83:cdcb81d1910f 578 }
nixnax 85:53e57ff1cf05 579
nixnax 87:9f5ac1fabd95 580 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 581 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 582
nixnax 83:cdcb81d1910f 583 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 584 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 585 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 586 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 587
nixnax 77:abf92baebb42 588 if (v2) {
nixnax 77:abf92baebb42 589 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 590 }
nixnax 67:a63e3486bcda 591 return n; // total byte size of our response
nixnax 67:a63e3486bcda 592 }
nixnax 67:a63e3486bcda 593
nixnax 67:a63e3486bcda 594
nixnax 29:30de79d658f6 595 void tcpHandler()
nixnax 29:30de79d658f6 596 {
nixnax 87:9f5ac1fabd95 597 // IP header
nixnax 87:9f5ac1fabd95 598
nixnax 26:11f4eb2663a7 599 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 600 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 601 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 602 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 603 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 604 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 605 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 606 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 607 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 608 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 609
nixnax 87:9f5ac1fabd95 610 // TCP header
nixnax 87:9f5ac1fabd95 611
nixnax 87:9f5ac1fabd95 612 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 613 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 614 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 615 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 616 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 617 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 618 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 619 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 620 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 621
nixnax 26:11f4eb2663a7 622 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 623 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 624 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 625
nixnax 87:9f5ac1fabd95 626 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 627 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 628 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 629
nixnax 85:53e57ff1cf05 630 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 631 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 632
nixnax 85:53e57ff1cf05 633 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 634 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 635
nixnax 28:1aa629be05e7 636
nixnax 29:30de79d658f6 637 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 638 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 639 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 640 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 641 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 642
nixnax 87:9f5ac1fabd95 643 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 644 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 645
nixnax 87:9f5ac1fabd95 646 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 647 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 648 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 649 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 650 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 651 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 652
nixnax 35:e7068df4d971 653 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 654 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 655 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 38:ab582987926e 656
nixnax 69:23f560087c16 657 // A sparse TCP flag interpreter that implements simple TCP connections from a single source
nixnax 69:23f560087c16 658 // Clients are allowed ONE push packet, after which the link is closed with a FIN flag in the ACK packet
nixnax 69:23f560087c16 659 // This strategy allows web browsers, netcat and curl to work ok while keeping the state machine simple
nixnax 77:abf92baebb42 660
nixnax 69:23f560087c16 661 switch ( flagsTCP ) {
nixnax 69:23f560087c16 662 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 663 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 664 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 665 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 666 break;
nixnax 77:abf92baebb42 667 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 69:23f560087c16 668 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // for every push we answer once AND close the link
nixnax 87:9f5ac1fabd95 669 if ( strncmp(tcpDataIn, "GET ", 4) == 0) { // check for an http GET command
nixnax 87:9f5ac1fabd95 670 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 69:23f560087c16 671 }
nixnax 69:23f560087c16 672 break;
nixnax 77:abf92baebb42 673 case TCP_FLAG_FIN:
nixnax 69:23f560087c16 674 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 85:53e57ff1cf05 675 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 676 break;
nixnax 77:abf92baebb42 677 default:
nixnax 69:23f560087c16 678 return; // ignore remaining packets
nixnax 28:1aa629be05e7 679 }
nixnax 81:9ede60e9a2c8 680
nixnax 77:abf92baebb42 681
nixnax 69:23f560087c16 682 // The TCP flag handling is now done
nixnax 38:ab582987926e 683 // Now we have to recalculate all the header sizes, swap IP address/port source and destination, and do the IP and TCP checksums
nixnax 26:11f4eb2663a7 684
nixnax 87:9f5ac1fabd95 685 ppp.ident++; // get next ident number for our packet
nixnax 83:cdcb81d1910f 686 ident[0] = ppp.ident>>8;
nixnax 83:cdcb81d1910f 687 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 83:cdcb81d1910f 688
nixnax 65:23b17c43aa0f 689 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 690 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 691 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 692 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 693
nixnax 60:2b770949c911 694 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 695 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 696 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 83:cdcb81d1910f 697
nixnax 87:9f5ac1fabd95 698 windowsizetcp[0]=4; // ignore window size negotiation
nixnax 82:051f77f7dd72 699 windowsizetcp[1]=0; // ignore winodw size negotiation
nixnax 29:30de79d658f6 700
nixnax 85:53e57ff1cf05 701 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 702 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 703 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 704 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 705
nixnax 85:53e57ff1cf05 706 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 707 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 708 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 709 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 710
nixnax 38:ab582987926e 711 flagbitstcp[1] = flagsOut; // set up the new flags
nixnax 38:ab582987926e 712
nixnax 38:ab582987926e 713 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 714 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 715 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 716 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 717 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 718
nixnax 38:ab582987926e 719 // the header is all set up, now do the IP and TCP checksums
nixnax 36:2a9b457f8276 720
nixnax 61:b3c1a04efd0a 721 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 722 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 723 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 724
nixnax 64:677b9713a120 725 // 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 726 // 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 727
nixnax 87:9f5ac1fabd95 728 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 729 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 730 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 731 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 732 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 733 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 734 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 735
nixnax 61:b3c1a04efd0a 736 // pseudo-header built, now we can calculate TCP checksum
nixnax 63:9253b0e1b7d8 737
nixnax 29:30de79d658f6 738 checksumtcp[0]=0;
nixnax 29:30de79d658f6 739 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 740 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 741 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 742 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 743 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 60:2b770949c911 744
nixnax 83:cdcb81d1910f 745 sendFrame(); // All preparation complete - send the TCP response
nixnax 83:cdcb81d1910f 746 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 747 dumpHeaderTCP();
nixnax 29:30de79d658f6 748 }
nixnax 26:11f4eb2663a7 749
nixnax 29:30de79d658f6 750 void dumpDataTCP()
nixnax 29:30de79d658f6 751 {
nixnax 26:11f4eb2663a7 752 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 753 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 754 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 755 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 756 if (v1) {
nixnax 42:4de44be70bfd 757 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 758 }
nixnax 29:30de79d658f6 759 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 760 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 761 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 762 }
nixnax 29:30de79d658f6 763 }
nixnax 26:11f4eb2663a7 764
nixnax 29:30de79d658f6 765 void TCPpacket()
nixnax 29:30de79d658f6 766 {
nixnax 83:cdcb81d1910f 767 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 768 dumpHeaderTCP();
nixnax 77:abf92baebb42 769 if (v2) {
nixnax 77:abf92baebb42 770 dumpDataTCP();
nixnax 77:abf92baebb42 771 }
nixnax 26:11f4eb2663a7 772 tcpHandler();
nixnax 11:f58998c24f0b 773 }
nixnax 11:f58998c24f0b 774
nixnax 29:30de79d658f6 775 void otherProtocol()
nixnax 29:30de79d658f6 776 {
nixnax 64:677b9713a120 777 debug("Other IP protocol");
nixnax 29:30de79d658f6 778 }
nixnax 26:11f4eb2663a7 779
nixnax 29:30de79d658f6 780 void IPframe()
nixnax 29:30de79d658f6 781 {
nixnax 10:74f8233f72c0 782 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 783 switch (protocol) {
nixnax 29:30de79d658f6 784 case 1:
nixnax 29:30de79d658f6 785 ICMPpacket();
nixnax 29:30de79d658f6 786 break;
nixnax 29:30de79d658f6 787 case 2:
nixnax 29:30de79d658f6 788 IGMPpacket();
nixnax 29:30de79d658f6 789 break;
nixnax 29:30de79d658f6 790 case 17:
nixnax 29:30de79d658f6 791 UDPpacket();
nixnax 29:30de79d658f6 792 break;
nixnax 29:30de79d658f6 793 case 6:
nixnax 29:30de79d658f6 794 TCPpacket();
nixnax 29:30de79d658f6 795 break;
nixnax 29:30de79d658f6 796 default:
nixnax 29:30de79d658f6 797 otherProtocol();
nixnax 29:30de79d658f6 798 }
nixnax 29:30de79d658f6 799 }
nixnax 9:0992486d4a30 800
nixnax 29:30de79d658f6 801 void LCPconfReq()
nixnax 29:30de79d658f6 802 {
nixnax 64:677b9713a120 803 debug("LCP Config ");
nixnax 9:0992486d4a30 804 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 805 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 806 debug("Reject\n");
nixnax 29:30de79d658f6 807 sendFrame();
nixnax 9:0992486d4a30 808 } else {
nixnax 9:0992486d4a30 809 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 810 debug("Ack\n");
nixnax 9:0992486d4a30 811 sendFrame();
nixnax 64:677b9713a120 812 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 813 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 814 sendFrame();
nixnax 9:0992486d4a30 815 }
nixnax 9:0992486d4a30 816 }
nixnax 9:0992486d4a30 817
nixnax 29:30de79d658f6 818 void LCPconfAck()
nixnax 29:30de79d658f6 819 {
nixnax 64:677b9713a120 820 debug("LCP Ack\n");
nixnax 29:30de79d658f6 821 }
nixnax 9:0992486d4a30 822
nixnax 29:30de79d658f6 823 void LCPend()
nixnax 29:30de79d658f6 824 {
nixnax 29:30de79d658f6 825 ppp.pkt.buf[4]=6;
nixnax 29:30de79d658f6 826 sendFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 827 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 828 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 829 debug("LCP End\n");
nixnax 9:0992486d4a30 830 }
nixnax 9:0992486d4a30 831
nixnax 29:30de79d658f6 832 void LCPother()
nixnax 29:30de79d658f6 833 {
nixnax 64:677b9713a120 834 debug("LCP Other\n");
nixnax 29:30de79d658f6 835 dumpFrame();
nixnax 29:30de79d658f6 836 }
nixnax 29:30de79d658f6 837
nixnax 29:30de79d658f6 838 void LCPframe()
nixnax 29:30de79d658f6 839 {
nixnax 29:30de79d658f6 840 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 841 switch (code) {
nixnax 29:30de79d658f6 842 case 1:
nixnax 29:30de79d658f6 843 LCPconfReq();
nixnax 29:30de79d658f6 844 break; // config request
nixnax 29:30de79d658f6 845 case 2:
nixnax 29:30de79d658f6 846 LCPconfAck();
nixnax 29:30de79d658f6 847 break; // config ack
nixnax 29:30de79d658f6 848 case 5:
nixnax 29:30de79d658f6 849 LCPend();
nixnax 29:30de79d658f6 850 break; // end connection
nixnax 29:30de79d658f6 851 default:
nixnax 29:30de79d658f6 852 LCPother();
nixnax 29:30de79d658f6 853 }
nixnax 9:0992486d4a30 854 }
nixnax 9:0992486d4a30 855
nixnax 29:30de79d658f6 856 void discardedFrame()
nixnax 29:30de79d658f6 857 {
nixnax 29:30de79d658f6 858 if (v0) {
nixnax 71:965619fedb3a 859 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 860 }
nixnax 9:0992486d4a30 861 }
nixnax 9:0992486d4a30 862
nixnax 29:30de79d658f6 863 void determinePacketType()
nixnax 29:30de79d658f6 864 {
nixnax 29:30de79d658f6 865 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 866 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 867 return;
nixnax 29:30de79d658f6 868 }
nixnax 29:30de79d658f6 869 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 870 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 871 return;
nixnax 29:30de79d658f6 872 }
nixnax 29:30de79d658f6 873 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 874 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 875 return;
nixnax 29:30de79d658f6 876 }
nixnax 9:0992486d4a30 877 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 878 switch (packetType) {
nixnax 29:30de79d658f6 879 case 0xc0:
nixnax 29:30de79d658f6 880 LCPframe();
nixnax 29:30de79d658f6 881 break; // link control
nixnax 29:30de79d658f6 882 case 0x80:
nixnax 29:30de79d658f6 883 IPCPframe();
nixnax 29:30de79d658f6 884 break; // IP control
nixnax 29:30de79d658f6 885 case 0x00:
nixnax 29:30de79d658f6 886 IPframe();
nixnax 29:30de79d658f6 887 break; // IP itself
nixnax 29:30de79d658f6 888 default:
nixnax 29:30de79d658f6 889 discardedFrame();
nixnax 9:0992486d4a30 890 }
nixnax 29:30de79d658f6 891 }
nixnax 9:0992486d4a30 892
nixnax 50:ad4e7c3c88e5 893 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 894 {
nixnax 85:53e57ff1cf05 895 while(1) {
nixnax 85:53e57ff1cf05 896 fillbuf();
nixnax 81:9ede60e9a2c8 897 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 898 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 899 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 900 if (rx==FRAME_7E) {
nixnax 81:9ede60e9a2c8 901 if (ppp.hdlc.frameFound == 0) { // we are still waiting for a frame start
nixnax 81:9ede60e9a2c8 902 ppp.hdlc.frameFound = 1; // we found our first frame start
nixnax 81:9ede60e9a2c8 903 ppp.hdlc.frameStartIndex=ppp.rx.tail; // remember where the frame character is in the buffer
nixnax 51:a86d56844324 904 } else {
nixnax 81:9ede60e9a2c8 905 // we have previously found a frame start
nixnax 81:9ede60e9a2c8 906 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 81:9ede60e9a2c8 907 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 81:9ede60e9a2c8 908 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 81:9ede60e9a2c8 909 break;
nixnax 50:ad4e7c3c88e5 910 }
nixnax 50:ad4e7c3c88e5 911 }
nixnax 50:ad4e7c3c88e5 912 }
nixnax 85:53e57ff1cf05 913 }
nixnax 50:ad4e7c3c88e5 914 }
nixnax 50:ad4e7c3c88e5 915
nixnax 29:30de79d658f6 916 void scanForConnectString()
nixnax 29:30de79d658f6 917 {
nixnax 81:9ede60e9a2c8 918 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 919 fillbuf();
nixnax 81:9ede60e9a2c8 920 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 81:9ede60e9a2c8 921 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENTCLIENT" );
nixnax 81:9ede60e9a2c8 922 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 923 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 924 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 925 if (found1 != NULL) {
nixnax 82:051f77f7dd72 926 memset(ppp.rx.buf, 0x20, RXBUFLEN); // clear the receive buffer
nixnax 81:9ede60e9a2c8 927 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 81:9ede60e9a2c8 928 pc.puts("CLIENTSERVER");
nixnax 81:9ede60e9a2c8 929 if (v0) debug("Found connect string \"CLIENTCLIENT\"\n");
nixnax 81:9ede60e9a2c8 930 }
nixnax 81:9ede60e9a2c8 931 if (found2 != NULL) {
nixnax 81:9ede60e9a2c8 932 if (v0) debug("Found HDLC frame start (7E)\n");
nixnax 81:9ede60e9a2c8 933 }
nixnax 71:965619fedb3a 934 ppp.online=1; // we are connected, so stop looking for the string
nixnax 9:0992486d4a30 935 }
nixnax 9:0992486d4a30 936 }
nixnax 81:9ede60e9a2c8 937
nixnax 9:0992486d4a30 938 }
nixnax 9:0992486d4a30 939
nixnax 0:2cf4880c312a 940 int main()
nixnax 0:2cf4880c312a 941 {
nixnax 14:c65831c25aaa 942 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 943 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 944 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 945 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 946 #endif
nixnax 9:0992486d4a30 947 pppInitStruct(); // initialize all the PPP properties
nixnax 81:9ede60e9a2c8 948 ppp.seq=1000; // initial TCP sequence number
nixnax 81:9ede60e9a2c8 949
nixnax 0:2cf4880c312a 950 while(1) {
nixnax 51:a86d56844324 951 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 952 while(ppp.online) {
nixnax 81:9ede60e9a2c8 953 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 954 }
nixnax 7:ab147f5e97ac 955 }
nixnax 7:ab147f5e97ac 956 }