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@92:cb962b365cce, 2017-07-23 (annotated)

Committer:
nixnax
Date:
Sun Jul 23 17:57:31 2017 +0000
Revision:
92:cb962b365cce
Parent:
91:5141ae9fba53
Child:
93:9675adc36882
Works with pppd on linux after small IPCP change.; Linux pppd command line in comments.

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 92:cb962b365cce 20 // https://www.microsoft.com/en-us/download/details.aspx?id=4865 - Microsoft network monitor - real-time monitoring of PPP packets -
nixnax 29:30de79d658f6 21 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 29:30de79d658f6 22 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html - Correctly calculates the 16-bit FCS (crc) on our frames (Choose CRC16_CCITT_FALSE)
nixnax 29:30de79d658f6 23 // https://technet.microsoft.com/en-us/sysinternals/pstools.aspx - psping for fast testing of ICMP ping function
nixnax 41:e58a5a09f411 24 // https://eternallybored.org/misc/netcat/ - use netcat -u 172.10.10.1 80 to send/receive UDP packets from PPP-Blinky
nixnax 91:5141ae9fba53 25 // Windows Powershell invoke-webrequest command - use it to stress test the webserver like this: while (1){ invoke-webrequest -uri 172.10.10.1/x }
nixnax 41:e58a5a09f411 26
nixnax 92:cb962b365cce 27 // Connecting PPP-Blinky to Linux
nixnax 92:cb962b365cce 28 // PPP-Blinky can be made to run on Linux - on Fedora, the following command, which uses pppd, works:
nixnax 92:cb962b365cce 29 // pppd /dev/ttyACM0 115200 debug dump local passive noccp novj updetach 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 92:cb962b365cce 31
nixnax 81:9ede60e9a2c8 32 #include "mbed.h"
nixnax 66:f005b9fdf4d1 33
nixnax 66:f005b9fdf4d1 34 // The #define below enables/disables a SECOND (optional) serial port that prints out interesting diagnostic messages.
nixnax 66:f005b9fdf4d1 35 // 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 36 #define SERIAL_PORT_MONITOR_NO /* or change to SERIAL_PORT_MONITOR_YES */
nixnax 0:2cf4880c312a 37
nixnax 41:e58a5a09f411 38 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 85:53e57ff1cf05 39
nixnax 85:53e57ff1cf05 40 // here we define the debug serial port for the various target boards
nixnax 85:53e57ff1cf05 41 // add yours if it's not in here
nixnax 88:b4a71242837c 42 #if defined(TARGET_LPC1768)
nixnax 85:53e57ff1cf05 43 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 44 #elif defined(TARGET_NUCLEO_F446RE) || defined(TARGET_NUCLEO_L152RE)
nixnax 85:53e57ff1cf05 45 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 46 #else
nixnax 85:53e57ff1cf05 47 #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 48 #endif
nixnax 85:53e57ff1cf05 49
nixnax 85:53e57ff1cf05 50
nixnax 42:4de44be70bfd 51 #define debug(x...) xx.printf (x)
nixnax 41:e58a5a09f411 52 #else
nixnax 42:4de44be70bfd 53 #define debug(x...) {}
nixnax 41:e58a5a09f411 54 #endif
nixnax 41:e58a5a09f411 55
nixnax 66:f005b9fdf4d1 56 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 90:55e0f243a7ce 57 #define v0 0
nixnax 66:f005b9fdf4d1 58 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 81:9ede60e9a2c8 59 #define v1 0
nixnax 77:abf92baebb42 60 // verbosity flag used in debug printouts - change to 0 to see less debug info. Lots of interesting info.
nixnax 77:abf92baebb42 61 #define v2 0
nixnax 29:30de79d658f6 62
nixnax 66:f005b9fdf4d1 63 // this is the webpage we serve when we get an HTTP request
nixnax 72:ad3d12753acf 64 // keep size under 900 bytes to fit into a single frame
nixnax 66:f005b9fdf4d1 65 const static char ourWebPage[] = "\
nixnax 66:f005b9fdf4d1 66 <!DOCTYPE html>\
nixnax 66:f005b9fdf4d1 67 <html>\
nixnax 66:f005b9fdf4d1 68 <head>\
nixnax 66:f005b9fdf4d1 69 <title>mbed-PPP-Blinky</title>\
nixnax 66:f005b9fdf4d1 70 <script>\
nixnax 66:f005b9fdf4d1 71 window.onload=function(){\
nixnax 66:f005b9fdf4d1 72 setInterval(function(){function x(){return document.getElementById('w');};\
nixnax 66:f005b9fdf4d1 73 x().textContent = parseInt(x().textContent)+1;},100);};\
nixnax 66:f005b9fdf4d1 74 </script>\
nixnax 66:f005b9fdf4d1 75 </head>\
nixnax 66:f005b9fdf4d1 76 <body style=\"font-family: sans-serif; font-size:30px; color:#807070\">\
nixnax 66:f005b9fdf4d1 77 <h1>mbed PPP-Blinky Up and Running</h1>\
nixnax 66:f005b9fdf4d1 78 <h1 id=\"w\" style=\"text-align:center;\">0</h1>\
nixnax 66:f005b9fdf4d1 79 <h1><a href=\"http://bit.ly/pppBlink2\">Source on mbed</a></h1>\
nixnax 66:f005b9fdf4d1 80 </body>\
nixnax 69:23f560087c16 81 </html>"; // around 464 bytes long
nixnax 69:23f560087c16 82
nixnax 69:23f560087c16 83
nixnax 66:f005b9fdf4d1 84
nixnax 73:2f56ec87dbe9 85 // 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 86 // On Windows the model type of the modem should be selected as "Communications cable between two computers"
nixnax 72:ad3d12753acf 87 // The modem baud rate should be set to 115200 baud
nixnax 72:ad3d12753acf 88 // See instructions at the top.
nixnax 73:2f56ec87dbe9 89 // 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 90 Serial pc(USBTX, USBRX); // usb virtual com port for mbed hardware
nixnax 29:30de79d658f6 91
nixnax 29:30de79d658f6 92 DigitalOut led1(LED1); // this led toggles when a packet is received
nixnax 4:a469050d5b80 93
nixnax 66:f005b9fdf4d1 94 // the standard hdlc frame start/end character. It's the tilde character "~"
nixnax 4:a469050d5b80 95 #define FRAME_7E (0x7e)
nixnax 29:30de79d658f6 96
nixnax 29:30de79d658f6 97 // the serial port receive buffer and packet buffer
nixnax 0:2cf4880c312a 98
nixnax 29:30de79d658f6 99 // a structure to keep all our ppp globals in
nixnax 29:30de79d658f6 100 struct pppType {
nixnax 38:ab582987926e 101 int online; // we hunt for a PPP connection if this is zero
nixnax 87:9f5ac1fabd95 102 unsigned int ident; // our IP ident value
nixnax 38:ab582987926e 103 unsigned int seq; // our TCP sequence number
nixnax 38:ab582987926e 104 int crc; // for calculating IP and TCP CRCs
nixnax 38:ab582987926e 105 int ledState; // state of LED1
nixnax 87:9f5ac1fabd95 106 int httpFrameCount;
nixnax 4:a469050d5b80 107 struct {
nixnax 81:9ede60e9a2c8 108 #define RXBUFLEN (1<<14)
nixnax 85:53e57ff1cf05 109 char buf[RXBUFLEN]; // RXBUFLEN MUST be a power of two because we use & operator for fast wrap-around in ring buffer
nixnax 72:ad3d12753acf 110 //char * buf;
nixnax 29:30de79d658f6 111 volatile int head;
nixnax 29:30de79d658f6 112 volatile int tail;
nixnax 81:9ede60e9a2c8 113 volatile int buflevel;
nixnax 38:ab582987926e 114 } rx; // serial port objects
nixnax 4:a469050d5b80 115 struct {
nixnax 38:ab582987926e 116 int len; // number of bytes in buffer
nixnax 38:ab582987926e 117 int crc; // PPP CRC (frame check)
nixnax 72:ad3d12753acf 118 //char * buf; // the actual buffer
nixnax 77:abf92baebb42 119 #define TCP_max_size 3300
nixnax 77:abf92baebb42 120 char buf[TCP_max_size]; // send and receive buffer large enough for unstuffed (decoded) hdlc frames
nixnax 38:ab582987926e 121 } pkt; // ppp buffer objects
nixnax 50:ad4e7c3c88e5 122 struct {
nixnax 50:ad4e7c3c88e5 123 int frameStartIndex; // frame start marker
nixnax 50:ad4e7c3c88e5 124 int frameEndIndex; // frame end marker
nixnax 81:9ede60e9a2c8 125 int frameFound; // we have found at least one start of frame already
nixnax 50:ad4e7c3c88e5 126 } hdlc; // hdlc frame objects
nixnax 29:30de79d658f6 127 };
nixnax 31:e000c1b9c565 128
nixnax 29:30de79d658f6 129 pppType ppp; // our global - definitely not thread safe
nixnax 0:2cf4880c312a 130
nixnax 60:2b770949c911 131 // Initialize our globals
nixnax 29:30de79d658f6 132 void pppInitStruct()
nixnax 29:30de79d658f6 133 {
nixnax 81:9ede60e9a2c8 134 memset( ppp.rx.buf, 0, RXBUFLEN);
nixnax 29:30de79d658f6 135 ppp.online=0;
nixnax 29:30de79d658f6 136 ppp.rx.tail=0;
nixnax 29:30de79d658f6 137 ppp.rx.head=0;
nixnax 81:9ede60e9a2c8 138 ppp.rx.buflevel=0;
nixnax 29:30de79d658f6 139 ppp.pkt.len=0;
nixnax 83:cdcb81d1910f 140 ppp.ident=1000;
nixnax 29:30de79d658f6 141 ppp.ledState=0;
nixnax 81:9ede60e9a2c8 142 ppp.hdlc.frameFound=0;
nixnax 81:9ede60e9a2c8 143 ppp.hdlc.frameStartIndex=0;
nixnax 87:9f5ac1fabd95 144 ppp.httpFrameCount=0;
nixnax 29:30de79d658f6 145 }
nixnax 26:11f4eb2663a7 146
nixnax 43:aa57db08995d 147 void led1Toggle()
nixnax 43:aa57db08995d 148 {
nixnax 43:aa57db08995d 149 ppp.ledState = ppp.ledState? 0 : 1;
nixnax 43:aa57db08995d 150 led1 = ppp.ledState;
nixnax 43:aa57db08995d 151 }
nixnax 43:aa57db08995d 152
nixnax 29:30de79d658f6 153 void crcReset()
nixnax 29:30de79d658f6 154 {
nixnax 29:30de79d658f6 155 ppp.crc=0xffff; // crc restart
nixnax 29:30de79d658f6 156 }
nixnax 4:a469050d5b80 157
nixnax 29:30de79d658f6 158 void crcDo(int x) // cumulative crc
nixnax 29:30de79d658f6 159 {
nixnax 29:30de79d658f6 160 for (int i=0; i<8; i++) {
nixnax 29:30de79d658f6 161 ppp.crc=((ppp.crc&1)^(x&1))?(ppp.crc>>1)^0x8408:ppp.crc>>1; // crc calculator
nixnax 29:30de79d658f6 162 x>>=1;
nixnax 29:30de79d658f6 163 }
nixnax 29:30de79d658f6 164 }
nixnax 29:30de79d658f6 165
nixnax 29:30de79d658f6 166 int crcBuf(char * buf, int size) // crc on an entire block of memory
nixnax 29:30de79d658f6 167 {
nixnax 31:e000c1b9c565 168 crcReset();
nixnax 31:e000c1b9c565 169 for(int i=0; i<size; i++)crcDo(*buf++);
nixnax 29:30de79d658f6 170 return ppp.crc;
nixnax 29:30de79d658f6 171 }
nixnax 0:2cf4880c312a 172
nixnax 85:53e57ff1cf05 173
nixnax 85:53e57ff1cf05 174 // fill our own receive buffer with characters from the PPP serial port
nixnax 85:53e57ff1cf05 175 void fillbuf()
nixnax 0:2cf4880c312a 176 {
nixnax 85:53e57ff1cf05 177 if ( pc.readable() ) {
nixnax 85:53e57ff1cf05 178 int hd = (ppp.rx.head+1)&(RXBUFLEN-1); // increment/wrap head index
nixnax 83:cdcb81d1910f 179 if ( hd == ppp.rx.tail ) {
nixnax 85:53e57ff1cf05 180 debug("\nReceive buffer full\n");
nixnax 85:53e57ff1cf05 181 return;
nixnax 83:cdcb81d1910f 182 }
nixnax 17:4918c893d802 183 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 184 ppp.rx.head = hd; // update head pointer
nixnax 81:9ede60e9a2c8 185 ppp.rx.buflevel++;
nixnax 15:b0154c910143 186 }
nixnax 0:2cf4880c312a 187 }
nixnax 0:2cf4880c312a 188
nixnax 85:53e57ff1cf05 189 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 190 {
nixnax 43:aa57db08995d 191 int emptyStatus = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 43:aa57db08995d 192 return emptyStatus;
nixnax 0:2cf4880c312a 193 }
nixnax 0:2cf4880c312a 194
nixnax 85:53e57ff1cf05 195 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 196 {
nixnax 63:9253b0e1b7d8 197 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 81:9ede60e9a2c8 198 ppp.rx.tail=(ppp.rx.tail+1)&(RXBUFLEN-1);
nixnax 81:9ede60e9a2c8 199 ppp.rx.buflevel--;
nixnax 63:9253b0e1b7d8 200 return x;
nixnax 0:2cf4880c312a 201 }
nixnax 0:2cf4880c312a 202
nixnax 50:ad4e7c3c88e5 203 void processHDLCFrame(int start, int end) // process received frame
nixnax 29:30de79d658f6 204 {
nixnax 38:ab582987926e 205 led1Toggle(); // change led1 state on every frame we receive
nixnax 29:30de79d658f6 206 if(start==end) {
nixnax 29:30de79d658f6 207 return;
nixnax 29:30de79d658f6 208 }
nixnax 9:0992486d4a30 209 crcReset();
nixnax 9:0992486d4a30 210 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 211 ppp.pkt.len=0;
nixnax 9:0992486d4a30 212 int unstuff=0;
nixnax 17:4918c893d802 213 int idx = start;
nixnax 17:4918c893d802 214 while(1) {
nixnax 9:0992486d4a30 215 if (unstuff==0) {
nixnax 72:ad3d12753acf 216 if (ppp.rx.buf[idx]==0x7d) unstuff=1;
nixnax 29:30de79d658f6 217 else {
nixnax 72:ad3d12753acf 218 *dest = ppp.rx.buf[idx];
nixnax 29:30de79d658f6 219 ppp.pkt.len++;
nixnax 29:30de79d658f6 220 dest++;
nixnax 72:ad3d12753acf 221 crcDo(ppp.rx.buf[idx]);
nixnax 29:30de79d658f6 222 }
nixnax 66:f005b9fdf4d1 223 } else { // unstuff characters prefixed with 0x7d
nixnax 72:ad3d12753acf 224 *dest = ppp.rx.buf[idx]^0x20;
nixnax 29:30de79d658f6 225 ppp.pkt.len++;
nixnax 29:30de79d658f6 226 dest++;
nixnax 72:ad3d12753acf 227 crcDo(ppp.rx.buf[idx]^0x20);
nixnax 9:0992486d4a30 228 unstuff=0;
nixnax 9:0992486d4a30 229 }
nixnax 81:9ede60e9a2c8 230 idx = (idx+1) & (RXBUFLEN-1);
nixnax 17:4918c893d802 231 if (idx == end) break;
nixnax 9:0992486d4a30 232 }
nixnax 29:30de79d658f6 233 ppp.pkt.crc = ppp.crc & 0xffff;
nixnax 9:0992486d4a30 234 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 235 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 236 determinePacketType();
nixnax 90:55e0f243a7ce 237 } else {
nixnax 90:55e0f243a7ce 238 debug("PPP FCS(crc) Error CRC=%x Length = %d\n",ppp.pkt.crc,ppp.pkt.len); // ignore packets with CRC errors but print a debug line
nixnax 9:0992486d4a30 239 }
nixnax 9:0992486d4a30 240 }
nixnax 9:0992486d4a30 241
nixnax 38:ab582987926e 242 // Note - the hex output of dumpFrame() can be imported into WireShark
nixnax 38:ab582987926e 243 // Capture the frame's hex output in your terminal program and save as a text file
nixnax 38:ab582987926e 244 // In WireShark, use "Import Hex File". Options are: Offset=None, Protocol=PPP.
nixnax 29:30de79d658f6 245 void dumpFrame()
nixnax 29:30de79d658f6 246 {
nixnax 42:4de44be70bfd 247 for(int i=0; i<ppp.pkt.len; i++) debug("%02x ", ppp.pkt.buf[i]);
nixnax 42:4de44be70bfd 248 debug(" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len);
nixnax 16:cb0b80c24ba2 249 }
nixnax 16:cb0b80c24ba2 250
nixnax 29:30de79d658f6 251 void hdlcPut(int ch) // do hdlc handling of special (flag) characters
nixnax 29:30de79d658f6 252 {
nixnax 29:30de79d658f6 253 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) {
nixnax 29:30de79d658f6 254 pc.putc(0x7d);
nixnax 66:f005b9fdf4d1 255 pc.putc(ch^0x20); // these characters need special handling
nixnax 29:30de79d658f6 256 } else {
nixnax 29:30de79d658f6 257 pc.putc(ch);
nixnax 29:30de79d658f6 258 }
nixnax 11:f58998c24f0b 259 }
nixnax 9:0992486d4a30 260
nixnax 85:53e57ff1cf05 261 void sendFrame() // send a PPP frame in HDLC format
nixnax 29:30de79d658f6 262 {
nixnax 17:4918c893d802 263 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 264 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 265 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 266 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 29:30de79d658f6 267 for(int i=0; i<ppp.pkt.len; i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 268 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 269 }
nixnax 9:0992486d4a30 270
nixnax 66:f005b9fdf4d1 271 void ipConfigRequestHandler()
nixnax 29:30de79d658f6 272 {
nixnax 92:cb962b365cce 273 debug("IPCP Conf Ack\n");
nixnax 92:cb962b365cce 274 ppp.pkt.buf[4]=2; // change code to ack
nixnax 92:cb962b365cce 275 sendFrame(); // blind acknowledge everything they ask for
nixnax 92:cb962b365cce 276 debug("IPCP Ask\n");
nixnax 92:cb962b365cce 277 // send our own request now
nixnax 92:cb962b365cce 278 ppp.pkt.buf[4]=1; // change code to request
nixnax 92:cb962b365cce 279 ppp.pkt.buf[5]++; // increment sequence number
nixnax 92:cb962b365cce 280 ppp.pkt.buf[7]=4; // no options requested
nixnax 92:cb962b365cce 281 sendFrame(); // this is our request
nixnax 92:cb962b365cce 282 return;
nixnax 9:0992486d4a30 283 }
nixnax 9:0992486d4a30 284
nixnax 29:30de79d658f6 285 void ipAckHandler()
nixnax 29:30de79d658f6 286 {
nixnax 64:677b9713a120 287 debug("IPCP Grant\n");
nixnax 29:30de79d658f6 288 }
nixnax 9:0992486d4a30 289
nixnax 29:30de79d658f6 290 void ipNackHandler()
nixnax 29:30de79d658f6 291 {
nixnax 64:677b9713a120 292 debug("IPCP Nack\n");
nixnax 29:30de79d658f6 293 }
nixnax 9:0992486d4a30 294
nixnax 29:30de79d658f6 295 void ipDefaultHandler()
nixnax 29:30de79d658f6 296 {
nixnax 64:677b9713a120 297 debug("IPCP Other\n");
nixnax 29:30de79d658f6 298 }
nixnax 29:30de79d658f6 299
nixnax 29:30de79d658f6 300 void IPCPframe()
nixnax 29:30de79d658f6 301 {
nixnax 9:0992486d4a30 302 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 303 switch (code) {
nixnax 29:30de79d658f6 304 case 1:
nixnax 66:f005b9fdf4d1 305 ipConfigRequestHandler();
nixnax 29:30de79d658f6 306 break;
nixnax 29:30de79d658f6 307 case 2:
nixnax 29:30de79d658f6 308 ipAckHandler();
nixnax 29:30de79d658f6 309 break;
nixnax 29:30de79d658f6 310 case 3:
nixnax 29:30de79d658f6 311 ipNackHandler();
nixnax 29:30de79d658f6 312 break;
nixnax 29:30de79d658f6 313 default:
nixnax 29:30de79d658f6 314 ipDefaultHandler();
nixnax 9:0992486d4a30 315 }
nixnax 29:30de79d658f6 316 }
nixnax 9:0992486d4a30 317
nixnax 29:30de79d658f6 318 void UDPpacket()
nixnax 29:30de79d658f6 319 {
nixnax 12:db0dc91f0231 320 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 321 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 29:30de79d658f6 322 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 63:9253b0e1b7d8 323 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 324 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 325 char * udpDst = udpBlock+2; // destination port
nixnax 63:9253b0e1b7d8 326 #endif
nixnax 12:db0dc91f0231 327 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 328 char * udpInf = udpBlock+8; // actual start of info
nixnax 63:9253b0e1b7d8 329 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 12:db0dc91f0231 330 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 331 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 332 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 333 char * dstIP = udpPkt+16; // udp dst addr
nixnax 55:43faae812be3 334 #endif
nixnax 29:30de79d658f6 335 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 336 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 81:9ede60e9a2c8 337 if(v0) debug("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort);
nixnax 81:9ede60e9a2c8 338 if(v0) debug("%d.%d.%d.%d:%d ", dstIP[0],dstIP[1],dstIP[2],dstIP[3],dstPort);
nixnax 83:cdcb81d1910f 339 if(v0) debug("Len %03d", udpLength);
nixnax 29:30de79d658f6 340 int printSize = udpLength;
nixnax 29:30de79d658f6 341 if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 81:9ede60e9a2c8 342 if (v1) {
nixnax 29:30de79d658f6 343 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 344 char ch = udpInf[i];
nixnax 29:30de79d658f6 345 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 346 debug("%c", ch);
nixnax 29:30de79d658f6 347 } else {
nixnax 64:677b9713a120 348 debug("_");
nixnax 29:30de79d658f6 349 }
nixnax 29:30de79d658f6 350 }
nixnax 29:30de79d658f6 351 }
nixnax 83:cdcb81d1910f 352 if (v0) debug("\n");
nixnax 12:db0dc91f0231 353 }
nixnax 11:f58998c24f0b 354
nixnax 76:00e208cceb8b 355 unsigned int dataCheckSum(unsigned char * ptr, int len)
nixnax 29:30de79d658f6 356 {
nixnax 77:abf92baebb42 357
nixnax 75:0d513869231f 358 unsigned int sum=0;
nixnax 76:00e208cceb8b 359 unsigned char placeHolder;
nixnax 29:30de79d658f6 360 if (len&1) {
nixnax 76:00e208cceb8b 361 placeHolder = ptr[len]; // when length is odd stuff in a zero byte
nixnax 76:00e208cceb8b 362 ptr[len]=0;
nixnax 29:30de79d658f6 363 }
nixnax 29:30de79d658f6 364 for (int i=0; i<len/2; i++) {
nixnax 76:00e208cceb8b 365 unsigned int hi = *ptr;
nixnax 29:30de79d658f6 366 ptr++;
nixnax 76:00e208cceb8b 367 unsigned int lo = *ptr;
nixnax 29:30de79d658f6 368 ptr++;
nixnax 76:00e208cceb8b 369 unsigned int val = ( (hi<<8) | lo );
nixnax 11:f58998c24f0b 370 sum = sum + val;
nixnax 11:f58998c24f0b 371 }
nixnax 29:30de79d658f6 372 if (len&1) {
nixnax 76:00e208cceb8b 373 ptr[len] = placeHolder; // restore the last byte for odd lengths
nixnax 29:30de79d658f6 374 }
nixnax 76:00e208cceb8b 375 sum = (sum & 0xffff) + (sum>>16);
nixnax 76:00e208cceb8b 376 sum = (sum & 0xffff) + (sum>>16); // sum one more time to catch any carry from the carry
nixnax 12:db0dc91f0231 377 return ~sum;
nixnax 29:30de79d658f6 378 }
nixnax 11:f58998c24f0b 379
nixnax 29:30de79d658f6 380 void headerCheckSum()
nixnax 29:30de79d658f6 381 {
nixnax 11:f58998c24f0b 382 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 383 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 384 int sum=0;
nixnax 11:f58998c24f0b 385
nixnax 29:30de79d658f6 386 for (int i=0; i<len/2; i++) {
nixnax 29:30de79d658f6 387 int hi = *ptr;
nixnax 29:30de79d658f6 388 ptr++;
nixnax 29:30de79d658f6 389 int lo = *ptr;
nixnax 29:30de79d658f6 390 ptr++;
nixnax 11:f58998c24f0b 391 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 392 sum = sum + val;
nixnax 11:f58998c24f0b 393 }
nixnax 11:f58998c24f0b 394 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 395 sum = ~sum;
nixnax 11:f58998c24f0b 396 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 397 ppp.pkt.buf[15]= (sum );
nixnax 29:30de79d658f6 398 }
nixnax 9:0992486d4a30 399
nixnax 29:30de79d658f6 400 void ICMPpacket() // internet control message protocol
nixnax 29:30de79d658f6 401 {
nixnax 12:db0dc91f0231 402 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 403 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 404 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 405 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 406 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 407 char * icmpSum = icmpType+2; // icmp checksum
nixnax 29:30de79d658f6 408 #define ICMP_TYPE_PING_REQUEST 8
nixnax 29:30de79d658f6 409 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 410 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 411 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 412 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 413 char * dstAdr = ipPkt+16;
nixnax 63:9253b0e1b7d8 414 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 18:3e35de1bc877 415 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 29:30de79d658f6 416 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 63:9253b0e1b7d8 417 #endif
nixnax 81:9ede60e9a2c8 418 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 419 if(v0) debug("Ident %04x Sequence %04d ",icmpIdent,icmpSequence);
nixnax 29:30de79d658f6 420 char src[4];
nixnax 29:30de79d658f6 421 char dst[4];
nixnax 12:db0dc91f0231 422 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 423 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 424 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 425 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 426 char * chkSum = ipPkt+10;
nixnax 29:30de79d658f6 427 chkSum[0]=0;
nixnax 29:30de79d658f6 428 chkSum[1]=0;
nixnax 12:db0dc91f0231 429 headerCheckSum(); // new ip header checksum
nixnax 29:30de79d658f6 430 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 431 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 29:30de79d658f6 432 icmpSum[0]=0;
nixnax 29:30de79d658f6 433 icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 434 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 76:00e208cceb8b 435 unsigned int sum = dataCheckSum( (unsigned char *)icmpType, icmpLength); // this checksum on icmp data portion
nixnax 76:00e208cceb8b 436 icmpSum[0]=(sum>>8)&0xff;
nixnax 76:00e208cceb8b 437 icmpSum[1]=(sum )&0xff; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 438
nixnax 16:cb0b80c24ba2 439 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 440 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 441 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 29:30de79d658f6 442 if (v0) {
nixnax 29:30de79d658f6 443 for (int i=0; i<printSize; i++) {
nixnax 29:30de79d658f6 444 char ch = icmpData[i];
nixnax 29:30de79d658f6 445 if (ch>31 && ch<127) {
nixnax 42:4de44be70bfd 446 debug("%c",ch);
nixnax 29:30de79d658f6 447 } else {
nixnax 64:677b9713a120 448 debug("_");
nixnax 29:30de79d658f6 449 }
nixnax 29:30de79d658f6 450 }
nixnax 64:677b9713a120 451 debug("\n");
nixnax 29:30de79d658f6 452 }
nixnax 15:b0154c910143 453 sendFrame(); // reply to the ping
nixnax 29:30de79d658f6 454
nixnax 12:db0dc91f0231 455 } else {
nixnax 29:30de79d658f6 456 if (v0) {
nixnax 42:4de44be70bfd 457 debug("ICMP type=%d \n", icmpType[0]);
nixnax 29:30de79d658f6 458 }
nixnax 11:f58998c24f0b 459 }
nixnax 11:f58998c24f0b 460 }
nixnax 11:f58998c24f0b 461
nixnax 29:30de79d658f6 462 void IGMPpacket() // internet group management protocol
nixnax 29:30de79d658f6 463 {
nixnax 29:30de79d658f6 464 if (v0) {
nixnax 42:4de44be70bfd 465 debug("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 29:30de79d658f6 466 }
nixnax 29:30de79d658f6 467 }
nixnax 11:f58998c24f0b 468
nixnax 29:30de79d658f6 469 void dumpHeaderIP ()
nixnax 29:30de79d658f6 470 {
nixnax 26:11f4eb2663a7 471 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 63:9253b0e1b7d8 472 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 26:11f4eb2663a7 473 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 474 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 475 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 476 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 477 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 478 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 479 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 480 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 481 char * protocol = ipPkt+9; // 1 byte
nixnax 77:abf92baebb42 482 char * headercheck= ipPkt+10; // 2 bytes
nixnax 63:9253b0e1b7d8 483 #endif
nixnax 26:11f4eb2663a7 484 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 485 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 29:30de79d658f6 486
nixnax 55:43faae812be3 487 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 29:30de79d658f6 488 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 489 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 490 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 491 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 492 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 493 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 494 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 495 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 496 int protocolIP = protocol[0];
nixnax 76:00e208cceb8b 497 unsigned int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 55:43faae812be3 498 #endif
nixnax 55:43faae812be3 499
nixnax 29:30de79d658f6 500 char srcIP [16];
nixnax 29:30de79d658f6 501 snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 85:53e57ff1cf05 502 fillbuf();
nixnax 29:30de79d658f6 503 char dstIP [16];
nixnax 29:30de79d658f6 504 snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 85:53e57ff1cf05 505 fillbuf();
nixnax 82:051f77f7dd72 506 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 507 fillbuf();
nixnax 42:4de44be70bfd 508 if (v0) debug("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP);
nixnax 29:30de79d658f6 509 }
nixnax 26:11f4eb2663a7 510
nixnax 29:30de79d658f6 511 void dumpHeaderTCP()
nixnax 29:30de79d658f6 512 {
nixnax 83:cdcb81d1910f 513 if( v0 ) {
nixnax 81:9ede60e9a2c8 514
nixnax 81:9ede60e9a2c8 515 int headerSizeIP = (ppp.pkt.buf[4]&0xf)*4; // header size of ip portion
nixnax 81:9ede60e9a2c8 516 char * tcpStart = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 63:9253b0e1b7d8 517 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 518 char * seqtcp = tcpStart + 4; // 4 bytes
nixnax 81:9ede60e9a2c8 519 char * acktcp = tcpStart + 8; // 4 bytes
nixnax 63:9253b0e1b7d8 520 #endif
nixnax 81:9ede60e9a2c8 521 char * flagbitstcp = tcpStart + 12; // 9 bits
nixnax 63:9253b0e1b7d8 522 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 81:9ede60e9a2c8 523 unsigned int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 81:9ede60e9a2c8 524 unsigned int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 63:9253b0e1b7d8 525 #endif
nixnax 81:9ede60e9a2c8 526 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 10:74f8233f72c0 527
nixnax 81:9ede60e9a2c8 528 char flagInfo[10]; // text string presentating the TCP flags
nixnax 81:9ede60e9a2c8 529 memset(flagInfo,'.', 9); // fill string with "........."
nixnax 81:9ede60e9a2c8 530 memset(flagInfo+9,0,1); // null terminate string
nixnax 66:f005b9fdf4d1 531
nixnax 81:9ede60e9a2c8 532 if (flags & (1<<0)) flagInfo[0]='F';
nixnax 81:9ede60e9a2c8 533 if (flags & (1<<1)) flagInfo[1]='S';
nixnax 81:9ede60e9a2c8 534 if (flags & (1<<2)) flagInfo[2]='R';
nixnax 81:9ede60e9a2c8 535 if (flags & (1<<3)) flagInfo[3]='P';
nixnax 81:9ede60e9a2c8 536 if (flags & (1<<4)) flagInfo[4]='A';
nixnax 81:9ede60e9a2c8 537 if (flags & (1<<5)) flagInfo[5]='U';
nixnax 81:9ede60e9a2c8 538 if (flags & (1<<6)) flagInfo[6]='E';
nixnax 81:9ede60e9a2c8 539 if (flags & (1<<7)) flagInfo[7]='C';
nixnax 81:9ede60e9a2c8 540 if (flags & (1<<8)) flagInfo[8]='N';
nixnax 81:9ede60e9a2c8 541 debug("TCP Flags %s Seq %u Ack %u\n", flagInfo, seq, ack); // show the flags in debug
nixnax 29:30de79d658f6 542 }
nixnax 29:30de79d658f6 543 }
nixnax 29:30de79d658f6 544
nixnax 68:0b74763ae67f 545 int httpResponse(char * dataStart)
nixnax 67:a63e3486bcda 546 {
nixnax 67:a63e3486bcda 547 int n=0; // number of bytes we have printed so far
nixnax 77:abf92baebb42 548 int nHeader; // byte size of HTTP header
nixnax 83:cdcb81d1910f 549 int contentLengthStart; // index where HTML starts
nixnax 89:2c8dd0c2a426 550 int xFetch, rootFetch; // temporary storage of strncmp results
nixnax 85:53e57ff1cf05 551
nixnax 87:9f5ac1fabd95 552 ppp.httpFrameCount++; // increment the number of frames we have made
nixnax 85:53e57ff1cf05 553
nixnax 89:2c8dd0c2a426 554 rootFetch = strncmp(dataStart, "GET / HTTP/1.1", 14); // found GET /
nixnax 89:2c8dd0c2a426 555 xFetch = strncmp(dataStart, "GET /x HTTP/1.1", 15); // found GET /x
nixnax 89:2c8dd0c2a426 556 if( (rootFetch==0) || (xFetch==0) ) {
nixnax 89:2c8dd0c2a426 557 n=n+sprintf(n+dataStart,"HTTP/1.1 200 OK\r\nServer: mbed-PPP-Blinky\r\n"); // 200 OK header
nixnax 83:cdcb81d1910f 558 } else {
nixnax 89:2c8dd0c2a426 559 n=n+sprintf(n+dataStart,"HTTP/1.1 404 Not Found\r\nServer: mbed-PPP-Blinky\r\n"); // 404 header
nixnax 83:cdcb81d1910f 560 }
nixnax 83:cdcb81d1910f 561 n=n+sprintf(n+dataStart,"Content-Length: "); // http header
nixnax 83:cdcb81d1910f 562 contentLengthStart = n; // remember where Content-Length is in buffer
nixnax 83:cdcb81d1910f 563 n=n+sprintf(n+dataStart,"?????\r\n"); // leave five spaces for content length - will be updated later
nixnax 83:cdcb81d1910f 564 n=n+sprintf(n+dataStart,"Connection: close\r\n"); // close connection immediately
nixnax 83:cdcb81d1910f 565 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 566 nHeader=n; // size of HTTP header
nixnax 84:456e73151f11 567 if( rootFetch == 0 ) {
nixnax 83:cdcb81d1910f 568 // this is where we insert our web page into the buffer
nixnax 83:cdcb81d1910f 569 n=n+sprintf(n+dataStart,"%s", ourWebPage);
nixnax 85:53e57ff1cf05 570 } else {
nixnax 89:2c8dd0c2a426 571 if (xFetch == 0) {
nixnax 89:2c8dd0c2a426 572
nixnax 89:2c8dd0c2a426 573 #define W3C_COMPLIANT_RESPONSE_NO
nixnax 89:2c8dd0c2a426 574 // change the above to W3C_COMPLIANT_RESPONSE_YES if you want a W3C.org compliant HTTP response
nixnax 89:2c8dd0c2a426 575 #ifdef W3C_COMPLIANT_RESPONSE_YES
nixnax 89:2c8dd0c2a426 576 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>mbed-ppp-blinky</title>"); // html title (W3C.org required element)
nixnax 89:2c8dd0c2a426 577 n=n+sprintf(n+dataStart,"<body>%d</body>",ppp.httpFrameCount); // body = the http frame count
nixnax 89:2c8dd0c2a426 578 #else
nixnax 89:2c8dd0c2a426 579 n=n+sprintf(n+dataStart,"%d",ppp.httpFrameCount); // not valid html but fast, most browsers and curl are ok with it
nixnax 89:2c8dd0c2a426 580 #endif
nixnax 89:2c8dd0c2a426 581
nixnax 89:2c8dd0c2a426 582 } else {
nixnax 89:2c8dd0c2a426 583 // all other requests get 404 Not Found response with a http frame count - nice for debugging
nixnax 89:2c8dd0c2a426 584 n=n+sprintf(n+dataStart,"<!DOCTYPE html><title>ppp-blinky-mbed</title>"); // html title (required element)
nixnax 89:2c8dd0c2a426 585 n=n+sprintf(n+dataStart,"<body>Not Found</body>"); // not found message
nixnax 89:2c8dd0c2a426 586 }
nixnax 83:cdcb81d1910f 587 }
nixnax 87:9f5ac1fabd95 588 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 589 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 590
nixnax 83:cdcb81d1910f 591 #define CONTENTLENGTHSIZE 5
nixnax 83:cdcb81d1910f 592 char contentLengthString[CONTENTLENGTHSIZE+1];
nixnax 83:cdcb81d1910f 593 snprintf(contentLengthString,CONTENTLENGTHSIZE+1,"%*d",CONTENTLENGTHSIZE,n-nHeader); // print Content-Length with leading spaces and fixed width equal to csize
nixnax 83:cdcb81d1910f 594 memcpy(dataStart+contentLengthStart, contentLengthString, CONTENTLENGTHSIZE); // copy Content-Length to it's place in the send buffer
nixnax 67:a63e3486bcda 595
nixnax 77:abf92baebb42 596 if (v2) {
nixnax 77:abf92baebb42 597 debug("HTTP Response: HTTP-header %d HTTP-content %d HTTP-total %d\n",nHeader,n-nHeader,n);
nixnax 77:abf92baebb42 598 }
nixnax 67:a63e3486bcda 599 return n; // total byte size of our response
nixnax 67:a63e3486bcda 600 }
nixnax 67:a63e3486bcda 601
nixnax 67:a63e3486bcda 602
nixnax 29:30de79d658f6 603 void tcpHandler()
nixnax 29:30de79d658f6 604 {
nixnax 87:9f5ac1fabd95 605 // IP header
nixnax 87:9f5ac1fabd95 606
nixnax 26:11f4eb2663a7 607 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 608 char * ihl = ipPkt; // bottom 4 bits
nixnax 83:cdcb81d1910f 609 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 610 char * ident = ipPkt+4; // 2 bytes
nixnax 28:1aa629be05e7 611 char * protocol = ipPkt+9; // 1 byte
nixnax 83:cdcb81d1910f 612 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 613 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 614 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 615 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 616 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 617
nixnax 87:9f5ac1fabd95 618 // TCP header
nixnax 87:9f5ac1fabd95 619
nixnax 87:9f5ac1fabd95 620 char * tcp = ppp.pkt.buf+4+headerSizeIP; // start of tcp packet
nixnax 87:9f5ac1fabd95 621 char * srctcp = tcp + 0; // 2 bytes
nixnax 87:9f5ac1fabd95 622 char * dsttcp = tcp + 2; // 2 bytes
nixnax 87:9f5ac1fabd95 623 char * seqtcp = tcp + 4; // 4 bytes
nixnax 87:9f5ac1fabd95 624 char * acktcp = tcp + 8; // 4 bytes
nixnax 87:9f5ac1fabd95 625 char * offset = tcp + 12; // 4 bits
nixnax 87:9f5ac1fabd95 626 char * flagbitstcp = tcp + 12; // 9 bits
nixnax 87:9f5ac1fabd95 627 char * windowsizetcp = tcp + 14; // 2 bytes
nixnax 87:9f5ac1fabd95 628 char * checksumtcp = tcp + 16; // 2 bytes
nixnax 26:11f4eb2663a7 629
nixnax 26:11f4eb2663a7 630 int tcpSize = packetLength - headerSizeIP;
nixnax 35:e7068df4d971 631 int headerSizeTCP = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 61:b3c1a04efd0a 632 int protocolIP = protocol[0];
nixnax 29:30de79d658f6 633
nixnax 87:9f5ac1fabd95 634 char * tcpDataIn = tcp + headerSizeTCP; // start of data block after TCP header
nixnax 67:a63e3486bcda 635 int tcpDataSize = tcpSize - headerSizeTCP; // size of data block after TCP header
nixnax 87:9f5ac1fabd95 636 char * tcpDataOut = tcp + 20; // start of outgoing data
nixnax 81:9ede60e9a2c8 637
nixnax 85:53e57ff1cf05 638 unsigned int seq_in = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 85:53e57ff1cf05 639 unsigned int ack_in = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 85:53e57ff1cf05 640
nixnax 85:53e57ff1cf05 641 unsigned int ack_out = seq_in + tcpDataSize;
nixnax 87:9f5ac1fabd95 642 unsigned int seq_out = ack_in; // use their version of our current sequence number
nixnax 81:9ede60e9a2c8 643
nixnax 28:1aa629be05e7 644
nixnax 29:30de79d658f6 645 #define TCP_FLAG_ACK (1<<4)
nixnax 29:30de79d658f6 646 #define TCP_FLAG_SYN (1<<1)
nixnax 29:30de79d658f6 647 #define TCP_FLAG_PSH (1<<3)
nixnax 29:30de79d658f6 648 #define TCP_FLAG_RST (1<<2)
nixnax 29:30de79d658f6 649 #define TCP_FLAG_FIN (1<<0)
nixnax 28:1aa629be05e7 650
nixnax 87:9f5ac1fabd95 651 // first we shorten the TCP response header to only 20 bytes.
nixnax 87:9f5ac1fabd95 652 // this means we ignore all TCP option requests
nixnax 87:9f5ac1fabd95 653
nixnax 87:9f5ac1fabd95 654 tcpSize = 20; // shorten total TCP packet size to 20 bytes (no data)
nixnax 87:9f5ac1fabd95 655 headerSizeTCP = 20; // shorten outgoing TCP header size 20 bytes
nixnax 87:9f5ac1fabd95 656 offset[0] = (headerSizeTCP/4)<<4; // shorten tcp header size to 20 bytes
nixnax 87:9f5ac1fabd95 657 packetLength = 40; // shorten total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 658 pktLen[1] = 40; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 659 pktLen[0] = 0; // set total packet size to 40 bytes (20 ip + 20 tcp)
nixnax 87:9f5ac1fabd95 660
nixnax 35:e7068df4d971 661 int dataLen = 0; // most of our responses will have zero TCP data, only a header
nixnax 38:ab582987926e 662 int flagsOut = TCP_FLAG_ACK; // the default case is an ACK packet
nixnax 87:9f5ac1fabd95 663 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1]; // the tcp flags we received
nixnax 92:cb962b365cce 664
nixnax 91:5141ae9fba53 665 windowsizetcp[0]=3; // ignore window size negotiation
nixnax 91:5141ae9fba53 666 windowsizetcp[1]=0; // ignore winodw size negotiation
nixnax 38:ab582987926e 667
nixnax 69:23f560087c16 668 // A sparse TCP flag interpreter that implements simple TCP connections from a single source
nixnax 69:23f560087c16 669 // Clients are allowed ONE push packet, after which the link is closed with a FIN flag in the ACK packet
nixnax 69:23f560087c16 670 // This strategy allows web browsers, netcat and curl to work ok while keeping the state machine simple
nixnax 77:abf92baebb42 671
nixnax 69:23f560087c16 672 switch ( flagsTCP ) {
nixnax 69:23f560087c16 673 case TCP_FLAG_SYN:
nixnax 87:9f5ac1fabd95 674 flagsOut = TCP_FLAG_SYN | TCP_FLAG_ACK; // something wants to connect - acknowledge it
nixnax 87:9f5ac1fabd95 675 seq_out = seq_in+0x1000U; // create a new sequence number using their sequence as a base
nixnax 85:53e57ff1cf05 676 ack_out++; // for SYN flag we have to increase the sequence by 1
nixnax 69:23f560087c16 677 break;
nixnax 77:abf92baebb42 678 case TCP_FLAG_ACK | TCP_FLAG_PSH:
nixnax 69:23f560087c16 679 flagsOut = TCP_FLAG_ACK | TCP_FLAG_FIN; // for every push we answer once AND close the link
nixnax 91:5141ae9fba53 680 windowsizetcp[0]=1; // reduce the receive window size even more
nixnax 87:9f5ac1fabd95 681 if ( strncmp(tcpDataIn, "GET ", 4) == 0) { // check for an http GET command
nixnax 87:9f5ac1fabd95 682 dataLen = httpResponse(tcpDataOut); // send an http response
nixnax 69:23f560087c16 683 }
nixnax 69:23f560087c16 684 break;
nixnax 77:abf92baebb42 685 case TCP_FLAG_FIN:
nixnax 69:23f560087c16 686 case TCP_FLAG_FIN | TCP_FLAG_ACK:
nixnax 85:53e57ff1cf05 687 ack_out++; // for FIN flag we always have to increase sequence by 1
nixnax 69:23f560087c16 688 break;
nixnax 77:abf92baebb42 689 default:
nixnax 69:23f560087c16 690 return; // ignore remaining packets
nixnax 28:1aa629be05e7 691 }
nixnax 81:9ede60e9a2c8 692
nixnax 77:abf92baebb42 693
nixnax 69:23f560087c16 694 // The TCP flag handling is now done
nixnax 38:ab582987926e 695 // 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 696
nixnax 87:9f5ac1fabd95 697 ppp.ident++; // get next ident number for our packet
nixnax 83:cdcb81d1910f 698 ident[0] = ppp.ident>>8;
nixnax 83:cdcb81d1910f 699 ident[1] = ppp.ident>>0; // insert OUR ident
nixnax 83:cdcb81d1910f 700
nixnax 65:23b17c43aa0f 701 char tempHold[12]; // it's 12 long because we later reuse it when building the TCP pseudo-header
nixnax 60:2b770949c911 702 memcpy(tempHold, srcAdr,4);
nixnax 65:23b17c43aa0f 703 memcpy(srcAdr, dstAdr,4);
nixnax 60:2b770949c911 704 memcpy(dstAdr, tempHold,4); // swap ip address source/dest
nixnax 60:2b770949c911 705
nixnax 60:2b770949c911 706 memcpy(tempHold, srctcp,2);
nixnax 65:23b17c43aa0f 707 memcpy(srctcp, dsttcp,2);
nixnax 60:2b770949c911 708 memcpy(dsttcp, tempHold,2); // swap ip port source/dest
nixnax 83:cdcb81d1910f 709
nixnax 85:53e57ff1cf05 710 acktcp[0]=ack_out>>24;
nixnax 85:53e57ff1cf05 711 acktcp[1]=ack_out>>16;
nixnax 85:53e57ff1cf05 712 acktcp[2]=ack_out>>8;
nixnax 85:53e57ff1cf05 713 acktcp[3]=ack_out>>0; // save ack 32-bit integer
nixnax 38:ab582987926e 714
nixnax 85:53e57ff1cf05 715 seqtcp[0]=seq_out>>24;
nixnax 85:53e57ff1cf05 716 seqtcp[1]=seq_out>>16;
nixnax 85:53e57ff1cf05 717 seqtcp[2]=seq_out>>8;
nixnax 85:53e57ff1cf05 718 seqtcp[3]=seq_out>>0; // save seq 32-bit integer
nixnax 38:ab582987926e 719
nixnax 38:ab582987926e 720 flagbitstcp[1] = flagsOut; // set up the new flags
nixnax 38:ab582987926e 721
nixnax 38:ab582987926e 722 int newPacketSize = headerSizeIP + headerSizeTCP + dataLen; // calculate size of the outgoing packet
nixnax 36:2a9b457f8276 723 pktLen[0] = (newPacketSize>>8);
nixnax 36:2a9b457f8276 724 pktLen[1]=newPacketSize; // ip total packet size
nixnax 36:2a9b457f8276 725 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 36:2a9b457f8276 726 tcpSize = headerSizeTCP + dataLen; // tcp packet size
nixnax 36:2a9b457f8276 727
nixnax 38:ab582987926e 728 // the header is all set up, now do the IP and TCP checksums
nixnax 36:2a9b457f8276 729
nixnax 61:b3c1a04efd0a 730 headercheck[0]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 731 headercheck[1]=0; // IP header checksum
nixnax 61:b3c1a04efd0a 732 headerCheckSum(); // calculate the IP header checksum
nixnax 63:9253b0e1b7d8 733
nixnax 64:677b9713a120 734 // 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 735 // 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 736
nixnax 87:9f5ac1fabd95 737 char * pseudoHeader = tcp-12; // mark the start of the TCP pseudo-header
nixnax 67:a63e3486bcda 738 memcpy(tempHold, pseudoHeader, 12); // preserve the 12 bytes of the IP header where the TCP pseudo-Header will be built
nixnax 61:b3c1a04efd0a 739 memcpy( pseudoHeader+0, srcAdr, 8); // IP source and destination addresses from IP header
nixnax 61:b3c1a04efd0a 740 memset( pseudoHeader+8, 0, 1); // reserved, set to zero
nixnax 61:b3c1a04efd0a 741 memset( pseudoHeader+9, protocolIP, 1); // protocol from IP header
nixnax 62:f192926e42f1 742 memset( pseudoHeader+10, tcpSize>>8, 1); // size of IP data (TCP packet size)
nixnax 62:f192926e42f1 743 memset( pseudoHeader+11, tcpSize, 1); // size of IP data (TCP packet size)
nixnax 38:ab582987926e 744
nixnax 61:b3c1a04efd0a 745 // pseudo-header built, now we can calculate TCP checksum
nixnax 63:9253b0e1b7d8 746
nixnax 29:30de79d658f6 747 checksumtcp[0]=0;
nixnax 29:30de79d658f6 748 checksumtcp[1]=0;
nixnax 76:00e208cceb8b 749 unsigned int pseudoHeaderSum=dataCheckSum((unsigned char *)pseudoHeader,tcpSize+12); // calculate the TCP checksum starting at the pseudo-header
nixnax 61:b3c1a04efd0a 750 checksumtcp[0]=pseudoHeaderSum>>8;
nixnax 61:b3c1a04efd0a 751 checksumtcp[1]=pseudoHeaderSum;
nixnax 87:9f5ac1fabd95 752 memcpy( tcp-12, tempHold, 12); // restore the 12 bytes that the pseudo-header overwrote
nixnax 60:2b770949c911 753
nixnax 83:cdcb81d1910f 754 sendFrame(); // All preparation complete - send the TCP response
nixnax 83:cdcb81d1910f 755 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 756 dumpHeaderTCP();
nixnax 29:30de79d658f6 757 }
nixnax 26:11f4eb2663a7 758
nixnax 29:30de79d658f6 759 void dumpDataTCP()
nixnax 29:30de79d658f6 760 {
nixnax 26:11f4eb2663a7 761 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 762 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 35:e7068df4d971 763 int headerSizeTCP = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 35:e7068df4d971 764 int dataLen = ipPktLen - ipHeaderLen - headerSizeTCP; // data is what's left after the two headers
nixnax 29:30de79d658f6 765 if (v1) {
nixnax 42:4de44be70bfd 766 debug("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, headerSizeTCP, dataLen); // 1 for more verbose
nixnax 29:30de79d658f6 767 }
nixnax 29:30de79d658f6 768 if (dataLen > 0) {
nixnax 47:00a5ca075f8f 769 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 770 debug("%s\n",ppp.pkt.buf+4+ipHeaderLen+headerSizeTCP); // show the data
nixnax 29:30de79d658f6 771 }
nixnax 29:30de79d658f6 772 }
nixnax 26:11f4eb2663a7 773
nixnax 29:30de79d658f6 774 void TCPpacket()
nixnax 29:30de79d658f6 775 {
nixnax 83:cdcb81d1910f 776 dumpHeaderIP();
nixnax 81:9ede60e9a2c8 777 dumpHeaderTCP();
nixnax 77:abf92baebb42 778 if (v2) {
nixnax 77:abf92baebb42 779 dumpDataTCP();
nixnax 77:abf92baebb42 780 }
nixnax 26:11f4eb2663a7 781 tcpHandler();
nixnax 11:f58998c24f0b 782 }
nixnax 11:f58998c24f0b 783
nixnax 29:30de79d658f6 784 void otherProtocol()
nixnax 29:30de79d658f6 785 {
nixnax 64:677b9713a120 786 debug("Other IP protocol");
nixnax 29:30de79d658f6 787 }
nixnax 26:11f4eb2663a7 788
nixnax 29:30de79d658f6 789 void IPframe()
nixnax 29:30de79d658f6 790 {
nixnax 10:74f8233f72c0 791 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 792 switch (protocol) {
nixnax 29:30de79d658f6 793 case 1:
nixnax 29:30de79d658f6 794 ICMPpacket();
nixnax 29:30de79d658f6 795 break;
nixnax 29:30de79d658f6 796 case 2:
nixnax 29:30de79d658f6 797 IGMPpacket();
nixnax 29:30de79d658f6 798 break;
nixnax 29:30de79d658f6 799 case 17:
nixnax 29:30de79d658f6 800 UDPpacket();
nixnax 29:30de79d658f6 801 break;
nixnax 29:30de79d658f6 802 case 6:
nixnax 29:30de79d658f6 803 TCPpacket();
nixnax 29:30de79d658f6 804 break;
nixnax 29:30de79d658f6 805 default:
nixnax 29:30de79d658f6 806 otherProtocol();
nixnax 29:30de79d658f6 807 }
nixnax 29:30de79d658f6 808 }
nixnax 9:0992486d4a30 809
nixnax 29:30de79d658f6 810 void LCPconfReq()
nixnax 29:30de79d658f6 811 {
nixnax 64:677b9713a120 812 debug("LCP Config ");
nixnax 9:0992486d4a30 813 if (ppp.pkt.buf[7] != 4) {
nixnax 85:53e57ff1cf05 814 ppp.pkt.buf[4]=4; // allow only "no options" which means Maximum Receive Unit (MRU) is 1500 bytes
nixnax 64:677b9713a120 815 debug("Reject\n");
nixnax 29:30de79d658f6 816 sendFrame();
nixnax 9:0992486d4a30 817 } else {
nixnax 9:0992486d4a30 818 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 64:677b9713a120 819 debug("Ack\n");
nixnax 9:0992486d4a30 820 sendFrame();
nixnax 64:677b9713a120 821 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 822 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 823 sendFrame();
nixnax 9:0992486d4a30 824 }
nixnax 9:0992486d4a30 825 }
nixnax 9:0992486d4a30 826
nixnax 29:30de79d658f6 827 void LCPconfAck()
nixnax 29:30de79d658f6 828 {
nixnax 64:677b9713a120 829 debug("LCP Ack\n");
nixnax 29:30de79d658f6 830 }
nixnax 9:0992486d4a30 831
nixnax 29:30de79d658f6 832 void LCPend()
nixnax 29:30de79d658f6 833 {
nixnax 29:30de79d658f6 834 ppp.pkt.buf[4]=6;
nixnax 29:30de79d658f6 835 sendFrame(); // acknowledge
nixnax 81:9ede60e9a2c8 836 ppp.online=0; // start hunting for connect string again
nixnax 81:9ede60e9a2c8 837 pppInitStruct(); // flush the receive buffer
nixnax 81:9ede60e9a2c8 838 debug("LCP End\n");
nixnax 9:0992486d4a30 839 }
nixnax 9:0992486d4a30 840
nixnax 29:30de79d658f6 841 void LCPother()
nixnax 29:30de79d658f6 842 {
nixnax 64:677b9713a120 843 debug("LCP Other\n");
nixnax 29:30de79d658f6 844 dumpFrame();
nixnax 29:30de79d658f6 845 }
nixnax 29:30de79d658f6 846
nixnax 29:30de79d658f6 847 void LCPframe()
nixnax 29:30de79d658f6 848 {
nixnax 29:30de79d658f6 849 int code = ppp.pkt.buf[4];
nixnax 29:30de79d658f6 850 switch (code) {
nixnax 29:30de79d658f6 851 case 1:
nixnax 29:30de79d658f6 852 LCPconfReq();
nixnax 29:30de79d658f6 853 break; // config request
nixnax 29:30de79d658f6 854 case 2:
nixnax 29:30de79d658f6 855 LCPconfAck();
nixnax 29:30de79d658f6 856 break; // config ack
nixnax 29:30de79d658f6 857 case 5:
nixnax 29:30de79d658f6 858 LCPend();
nixnax 29:30de79d658f6 859 break; // end connection
nixnax 29:30de79d658f6 860 default:
nixnax 29:30de79d658f6 861 LCPother();
nixnax 29:30de79d658f6 862 }
nixnax 9:0992486d4a30 863 }
nixnax 9:0992486d4a30 864
nixnax 29:30de79d658f6 865 void discardedFrame()
nixnax 29:30de79d658f6 866 {
nixnax 29:30de79d658f6 867 if (v0) {
nixnax 71:965619fedb3a 868 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 869 }
nixnax 9:0992486d4a30 870 }
nixnax 9:0992486d4a30 871
nixnax 29:30de79d658f6 872 void determinePacketType()
nixnax 29:30de79d658f6 873 {
nixnax 29:30de79d658f6 874 if ( ppp.pkt.buf[0] != 0xff ) {
nixnax 64:677b9713a120 875 debug("byte0 != ff\n");
nixnax 29:30de79d658f6 876 return;
nixnax 29:30de79d658f6 877 }
nixnax 29:30de79d658f6 878 if ( ppp.pkt.buf[1] != 3 ) {
nixnax 64:677b9713a120 879 debug("byte1 != 3\n");
nixnax 29:30de79d658f6 880 return;
nixnax 29:30de79d658f6 881 }
nixnax 29:30de79d658f6 882 if ( ppp.pkt.buf[3] != 0x21 ) {
nixnax 64:677b9713a120 883 debug("byte2 != 21\n");
nixnax 29:30de79d658f6 884 return;
nixnax 29:30de79d658f6 885 }
nixnax 9:0992486d4a30 886 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 887 switch (packetType) {
nixnax 29:30de79d658f6 888 case 0xc0:
nixnax 29:30de79d658f6 889 LCPframe();
nixnax 29:30de79d658f6 890 break; // link control
nixnax 29:30de79d658f6 891 case 0x80:
nixnax 29:30de79d658f6 892 IPCPframe();
nixnax 29:30de79d658f6 893 break; // IP control
nixnax 29:30de79d658f6 894 case 0x00:
nixnax 29:30de79d658f6 895 IPframe();
nixnax 29:30de79d658f6 896 break; // IP itself
nixnax 29:30de79d658f6 897 default:
nixnax 29:30de79d658f6 898 discardedFrame();
nixnax 9:0992486d4a30 899 }
nixnax 29:30de79d658f6 900 }
nixnax 9:0992486d4a30 901
nixnax 50:ad4e7c3c88e5 902 void wait_for_HDLC_frame()
nixnax 50:ad4e7c3c88e5 903 {
nixnax 85:53e57ff1cf05 904 while(1) {
nixnax 85:53e57ff1cf05 905 fillbuf();
nixnax 81:9ede60e9a2c8 906 if ( rxbufNotEmpty() ) {
nixnax 81:9ede60e9a2c8 907 int oldTail = ppp.rx.tail; // remember where the character is located in the buffer
nixnax 81:9ede60e9a2c8 908 int rx = pc_getBuf(); // get the character
nixnax 50:ad4e7c3c88e5 909 if (rx==FRAME_7E) {
nixnax 81:9ede60e9a2c8 910 if (ppp.hdlc.frameFound == 0) { // we are still waiting for a frame start
nixnax 81:9ede60e9a2c8 911 ppp.hdlc.frameFound = 1; // we found our first frame start
nixnax 81:9ede60e9a2c8 912 ppp.hdlc.frameStartIndex=ppp.rx.tail; // remember where the frame character is in the buffer
nixnax 51:a86d56844324 913 } else {
nixnax 81:9ede60e9a2c8 914 // we have previously found a frame start
nixnax 81:9ede60e9a2c8 915 ppp.hdlc.frameEndIndex=oldTail; // mark the frame end character
nixnax 81:9ede60e9a2c8 916 processHDLCFrame(ppp.hdlc.frameStartIndex, ppp.hdlc.frameEndIndex); // process the frame
nixnax 81:9ede60e9a2c8 917 ppp.hdlc.frameStartIndex = ppp.rx.tail; // where next frame will start
nixnax 81:9ede60e9a2c8 918 break;
nixnax 50:ad4e7c3c88e5 919 }
nixnax 50:ad4e7c3c88e5 920 }
nixnax 50:ad4e7c3c88e5 921 }
nixnax 85:53e57ff1cf05 922 }
nixnax 50:ad4e7c3c88e5 923 }
nixnax 50:ad4e7c3c88e5 924
nixnax 29:30de79d658f6 925 void scanForConnectString()
nixnax 29:30de79d658f6 926 {
nixnax 81:9ede60e9a2c8 927 while(ppp.online == 0) {
nixnax 85:53e57ff1cf05 928 fillbuf();
nixnax 81:9ede60e9a2c8 929 // search for Windows Dialup Networking "Direct Connection Between Two Computers" expected connect string
nixnax 81:9ede60e9a2c8 930 char * found1 = strstr( (char *)ppp.rx.buf, "CLIENTCLIENT" );
nixnax 81:9ede60e9a2c8 931 // also search for HDLC frame start character 0x7e
nixnax 81:9ede60e9a2c8 932 void * found2 = memchr( (char *)ppp.rx.buf, 0x7e, RXBUFLEN );
nixnax 81:9ede60e9a2c8 933 if( (found1 != NULL) | (found2 != NULL) ) {
nixnax 81:9ede60e9a2c8 934 if (found1 != NULL) {
nixnax 81:9ede60e9a2c8 935 // respond with Windows Dialup networking expected "Direct Connection Between Two Computers" response string
nixnax 81:9ede60e9a2c8 936 pc.puts("CLIENTSERVER");
nixnax 81:9ede60e9a2c8 937 if (v0) debug("Found connect string \"CLIENTCLIENT\"\n");
nixnax 81:9ede60e9a2c8 938 }
nixnax 81:9ede60e9a2c8 939 if (found2 != NULL) {
nixnax 81:9ede60e9a2c8 940 if (v0) debug("Found HDLC frame start (7E)\n");
nixnax 81:9ede60e9a2c8 941 }
nixnax 71:965619fedb3a 942 ppp.online=1; // we are connected, so stop looking for the string
nixnax 9:0992486d4a30 943 }
nixnax 9:0992486d4a30 944 }
nixnax 81:9ede60e9a2c8 945
nixnax 9:0992486d4a30 946 }
nixnax 9:0992486d4a30 947
nixnax 0:2cf4880c312a 948 int main()
nixnax 0:2cf4880c312a 949 {
nixnax 14:c65831c25aaa 950 pc.baud(115200); // USB virtual serial port
nixnax 41:e58a5a09f411 951 #ifndef SERIAL_PORT_MONITOR_NO
nixnax 49:2213f9c132b2 952 xx.baud(115200); // second serial port for debug messages
nixnax 9:0992486d4a30 953 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 41:e58a5a09f411 954 #endif
nixnax 9:0992486d4a30 955 pppInitStruct(); // initialize all the PPP properties
nixnax 81:9ede60e9a2c8 956 ppp.seq=1000; // initial TCP sequence number
nixnax 81:9ede60e9a2c8 957
nixnax 0:2cf4880c312a 958 while(1) {
nixnax 51:a86d56844324 959 scanForConnectString(); // respond to connect command from windows dial up networking
nixnax 81:9ede60e9a2c8 960 while(ppp.online) {
nixnax 81:9ede60e9a2c8 961 wait_for_HDLC_frame();
nixnax 81:9ede60e9a2c8 962 }
nixnax 7:ab147f5e97ac 963 }
nixnax 7:ab147f5e97ac 964 }