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@26:11f4eb2663a7, 2017-01-03 (annotated)

Committer:
nixnax
Date:
Tue Jan 03 02:54:53 2017 +0000
Revision:
26:11f4eb2663a7
Parent:
25:0b0450e1b08b
Child:
27:78d194dd8799
TCP starting to work - getting packets echoed

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 0:2cf4880c312a 1 #include "mbed.h"
nixnax 0:2cf4880c312a 2
nixnax 12:db0dc91f0231 3 // Copyright 2016 Nicolas Nackel. 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 12:db0dc91f0231 4
nixnax 0:2cf4880c312a 5 // Proof-of-concept for TCP/IP using Windows 7/8/10 Dial Up Networking over MBED USB Virtual COM Port
nixnax 0:2cf4880c312a 6
nixnax 4:a469050d5b80 7 // Toggles LED1 every time the PC sends an IP packet over the PPP link
nixnax 4:a469050d5b80 8
nixnax 4:a469050d5b80 9 // Note - turn off all authentication, passwords, compression etc. Simplest link possible.
nixnax 0:2cf4880c312a 10
nixnax 9:0992486d4a30 11 // Handy links
nixnax 19:e53cdee9a33c 12 // https://developer.mbed.org/users/nixnax/code/PPP-Blinky/ - introduction and notes
nixnax 6:fba4c2e817b8 13 // http://atari.kensclassics.org/wcomlog.htm
nixnax 6:fba4c2e817b8 14 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 6:fba4c2e817b8 15 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
nixnax 9:0992486d4a30 16 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 19:e53cdee9a33c 17 // http://pingtester.net/ - nice tool for high rate ping testing
nixnax 6:fba4c2e817b8 18
nixnax 6:fba4c2e817b8 19 Serial pc(USBTX, USBRX); // The USB com port - Set this up as a Dial-Up Modem on your pc
nixnax 15:b0154c910143 20 Serial xx(PC_10, PC_11); // debug((((( port - use an additional USB serial port to monitor this
nixnax 0:2cf4880c312a 21
nixnax 19:e53cdee9a33c 22 // the second #define below gets rid of all the debug printfs
nixnax 20:5db9b77b38a6 23 #define debug(x) xx.printf x
nixnax 19:e53cdee9a33c 24 //#define debug(x) {}
nixnax 9:0992486d4a30 25
nixnax 4:a469050d5b80 26 DigitalOut led1(LED1);
nixnax 4:a469050d5b80 27
nixnax 4:a469050d5b80 28 #define FRAME_7E (0x7e)
nixnax 19:e53cdee9a33c 29 #define BUFLEN (1<<14)
nixnax 20:5db9b77b38a6 30 char rxbuf[BUFLEN];
nixnax 17:4918c893d802 31 char frbuf[6000]; // buffer for ppp frame
nixnax 0:2cf4880c312a 32
nixnax 4:a469050d5b80 33 struct {
nixnax 4:a469050d5b80 34 int online;
nixnax 26:11f4eb2663a7 35 int ident;
nixnax 4:a469050d5b80 36 struct {
nixnax 20:5db9b77b38a6 37 char * buf;
nixnax 15:b0154c910143 38 volatile int head;
nixnax 20:5db9b77b38a6 39 volatile int tail;
nixnax 9:0992486d4a30 40 int total;
nixnax 4:a469050d5b80 41 } rx; // serial port buffer
nixnax 4:a469050d5b80 42 struct {
nixnax 6:fba4c2e817b8 43 int id;
nixnax 4:a469050d5b80 44 int len;
nixnax 4:a469050d5b80 45 int crc;
nixnax 4:a469050d5b80 46 char * buf;
nixnax 4:a469050d5b80 47 } pkt; // ppp buffer
nixnax 4:a469050d5b80 48 } ppp;
nixnax 0:2cf4880c312a 49
nixnax 26:11f4eb2663a7 50 struct tcpType {
nixnax 26:11f4eb2663a7 51 int connect;
nixnax 26:11f4eb2663a7 52 int ack;
nixnax 26:11f4eb2663a7 53 int seq;
nixnax 26:11f4eb2663a7 54 };
nixnax 26:11f4eb2663a7 55
nixnax 26:11f4eb2663a7 56 tcpType tcp;
nixnax 26:11f4eb2663a7 57
nixnax 26:11f4eb2663a7 58
nixnax 26:11f4eb2663a7 59 void pppInitStruct(){ ppp.online=0; ppp.rx.buf=rxbuf; ppp.rx.tail=0; ppp.rx.head=0; ppp.rx.total=0; ppp.pkt.buf=frbuf; ppp.pkt.len=0; ppp.ident=0;}
nixnax 4:a469050d5b80 60
nixnax 4:a469050d5b80 61 int crcG; // frame check sequence (CRC) holder
nixnax 4:a469050d5b80 62 void crcDo(int x){for (int i=0;i<8;i++){crcG=((crcG&1)^(x&1))?(crcG>>1)^0x8408:crcG>>1;x>>=1;}} // crc calculator
nixnax 4:a469050d5b80 63 void crcReset(){crcG=0xffff;} // crc restart
nixnax 9:0992486d4a30 64 int crcBuf(char * buf, int size){crcReset();for(int i=0;i<size;i++)crcDo(*buf++);return crcG;} // crc on a block of memory
nixnax 0:2cf4880c312a 65
nixnax 0:2cf4880c312a 66 void rxHandler() // serial port receive interrupt handler
nixnax 0:2cf4880c312a 67 {
nixnax 17:4918c893d802 68 while ( pc.readable() ) {
nixnax 20:5db9b77b38a6 69 int hd = (ppp.rx.head+1)&(BUFLEN-1); // increment/wrap
nixnax 20:5db9b77b38a6 70 if ( hd == ppp.rx.tail ) break; // watch for buffer full
nixnax 17:4918c893d802 71 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 72 ppp.rx.head = hd; // update head pointer
nixnax 15:b0154c910143 73 }
nixnax 0:2cf4880c312a 74 }
nixnax 0:2cf4880c312a 75
nixnax 14:c65831c25aaa 76 int ledState=0;
nixnax 14:c65831c25aaa 77 void led1Toggle(){
nixnax 14:c65831c25aaa 78 ledState = ledState? 0 : 1;
nixnax 14:c65831c25aaa 79 led1 = ledState;
nixnax 14:c65831c25aaa 80 }
nixnax 14:c65831c25aaa 81
nixnax 22:00df34cd4d7e 82 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 83 {
nixnax 22:00df34cd4d7e 84 __disable_irq(); // critical section start
nixnax 22:00df34cd4d7e 85 int notEmpty = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 22:00df34cd4d7e 86 __enable_irq(); // critical section end
nixnax 22:00df34cd4d7e 87 return notEmpty;
nixnax 0:2cf4880c312a 88 }
nixnax 0:2cf4880c312a 89
nixnax 0:2cf4880c312a 90 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 91 {
nixnax 22:00df34cd4d7e 92 if ( rxbufNotEmpty() ) {
nixnax 4:a469050d5b80 93 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 20:5db9b77b38a6 94 __disable_irq(); // critical section start
nixnax 22:00df34cd4d7e 95 ppp.rx.tail=(ppp.rx.tail+1)&(BUFLEN-1);
nixnax 20:5db9b77b38a6 96 __enable_irq(); // critical section end
nixnax 0:2cf4880c312a 97 return x;
nixnax 20:5db9b77b38a6 98 } else return -1;
nixnax 0:2cf4880c312a 99 }
nixnax 0:2cf4880c312a 100
nixnax 4:a469050d5b80 101 void scanForConnectString(); // scan for connect attempts from pc
nixnax 1:9e03798d4367 102
nixnax 9:0992486d4a30 103 void processFrame(int start, int end) { // process received frame
nixnax 14:c65831c25aaa 104 led1Toggle(); // change led1 state when frames are received
nixnax 15:b0154c910143 105 if(start==end) { pc.putc(0x7e); return; }
nixnax 9:0992486d4a30 106 crcReset();
nixnax 9:0992486d4a30 107 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 108 ppp.pkt.len=0;
nixnax 9:0992486d4a30 109 int unstuff=0;
nixnax 17:4918c893d802 110 int idx = start;
nixnax 17:4918c893d802 111 while(1) {
nixnax 9:0992486d4a30 112 if (unstuff==0) {
nixnax 17:4918c893d802 113 if (rxbuf[idx]==0x7d) unstuff=1;
nixnax 17:4918c893d802 114 else { *dest = rxbuf[idx]; ppp.pkt.len++; dest++; crcDo(rxbuf[idx]); }
nixnax 12:db0dc91f0231 115 } else { // unstuff
nixnax 17:4918c893d802 116 *dest = rxbuf[idx]^0x20; ppp.pkt.len++; dest++; crcDo(rxbuf[idx]^0x20);
nixnax 9:0992486d4a30 117 unstuff=0;
nixnax 9:0992486d4a30 118 }
nixnax 17:4918c893d802 119 idx = (idx+1) & (BUFLEN-1);
nixnax 17:4918c893d802 120 if (idx == end) break;
nixnax 9:0992486d4a30 121 }
nixnax 9:0992486d4a30 122 ppp.pkt.crc = crcG & 0xffff;
nixnax 9:0992486d4a30 123 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 124 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 125 determinePacketType();
nixnax 12:db0dc91f0231 126 } else { // crc error
nixnax 15:b0154c910143 127 debug(("CRC is %x Len is %d\n",ppp.pkt.crc,ppp.pkt.len));
nixnax 15:b0154c910143 128 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 15:b0154c910143 129 debug(("\n"));
nixnax 9:0992486d4a30 130 }
nixnax 9:0992486d4a30 131 }
nixnax 9:0992486d4a30 132
nixnax 11:f58998c24f0b 133 void dumpFrame() {
nixnax 16:cb0b80c24ba2 134 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 16:cb0b80c24ba2 135 debug((" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len));
nixnax 16:cb0b80c24ba2 136 }
nixnax 16:cb0b80c24ba2 137
nixnax 16:cb0b80c24ba2 138 void hdlcPut(int ch) { // do hdlc handling of special (flag) characters
nixnax 16:cb0b80c24ba2 139 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) { pc.putc(0x7d); pc.putc(ch^0x20); } else { pc.putc(ch); }
nixnax 11:f58998c24f0b 140 }
nixnax 9:0992486d4a30 141
nixnax 9:0992486d4a30 142 void sendFrame(){
nixnax 26:11f4eb2663a7 143 ppp.ident++;
nixnax 17:4918c893d802 144 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 145 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 146 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 147 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 16:cb0b80c24ba2 148 for(int i=0;i<ppp.pkt.len;i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 149 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 150 }
nixnax 9:0992486d4a30 151
nixnax 9:0992486d4a30 152 void ipRequestHandler(){
nixnax 15:b0154c910143 153 debug(("IPCP Conf "));
nixnax 9:0992486d4a30 154 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 15:b0154c910143 155 debug(("Rej\n")); // reject if any options are requested
nixnax 9:0992486d4a30 156 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 157 sendFrame();
nixnax 9:0992486d4a30 158 } else {
nixnax 15:b0154c910143 159 debug(("Ack\n"));
nixnax 9:0992486d4a30 160 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 161 sendFrame(); // acknowledge
nixnax 15:b0154c910143 162 debug(("IPCP Ask\n"));
nixnax 9:0992486d4a30 163 // send our own request now
nixnax 12:db0dc91f0231 164 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 165 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 166 sendFrame(); // this is our request
nixnax 9:0992486d4a30 167 }
nixnax 9:0992486d4a30 168 }
nixnax 9:0992486d4a30 169
nixnax 15:b0154c910143 170 void ipAckHandler(){ debug(("IPCP Grant\n")); }
nixnax 9:0992486d4a30 171
nixnax 15:b0154c910143 172 void ipNackHandler(){ debug(("IPCP Nack\n")); }
nixnax 9:0992486d4a30 173
nixnax 15:b0154c910143 174 void ipDefaultHandler(){ debug(("IPCP Other\n")); }
nixnax 9:0992486d4a30 175
nixnax 9:0992486d4a30 176 void IPCPframe() {
nixnax 9:0992486d4a30 177 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 178 switch (code) {
nixnax 9:0992486d4a30 179 case 1: ipRequestHandler(); break;
nixnax 9:0992486d4a30 180 case 2: ipAckHandler(); break;
nixnax 9:0992486d4a30 181 case 3: ipNackHandler(); break;
nixnax 9:0992486d4a30 182 default: ipDefaultHandler();
nixnax 9:0992486d4a30 183 }
nixnax 9:0992486d4a30 184 }
nixnax 9:0992486d4a30 185
nixnax 10:74f8233f72c0 186 void UDPpacket() {
nixnax 12:db0dc91f0231 187 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 188 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 189 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 12:db0dc91f0231 190 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 191 char * udpDst = udpBlock+2; // destination port
nixnax 12:db0dc91f0231 192 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 193 char * udpInf = udpBlock+8; // actual start of info
nixnax 12:db0dc91f0231 194 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 195 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 196 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 197 char * dstIP = udpPkt+16; // udp dst addr
nixnax 12:db0dc91f0231 198 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 199 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 15:b0154c910143 200 debug(("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort));
nixnax 15:b0154c910143 201 debug(("%d.%d.%d.%d:%d ", dstIP[1],dstIP[1],dstIP[1],dstIP[1],dstPort));
nixnax 15:b0154c910143 202 debug(("Len %d ", udpLength));
nixnax 13:d882b8a042b4 203 int printSize = udpLength; if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 16:cb0b80c24ba2 204 for (int i=0; i<printSize; i++) { char ch = udpInf[i]; if (ch>31 && ch<127) { debug(("%c", ch)); } else { debug(("_")); } }
nixnax 15:b0154c910143 205 debug(("\n"));
nixnax 12:db0dc91f0231 206 }
nixnax 11:f58998c24f0b 207
nixnax 11:f58998c24f0b 208 int dataCheckSum(char * ptr, int len) {
nixnax 23:af88d429bed1 209 int sum=0; int placeHolder;
nixnax 25:0b0450e1b08b 210 if (len&1) { placeHolder = ptr[len-1]; ptr[len-1]=0; } // when length is odd zero stuff
nixnax 11:f58998c24f0b 211 for (int i=0;i<len/2;i++) {
nixnax 25:0b0450e1b08b 212 int hi = *ptr; ptr++; int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 213 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 214 sum = sum + val;
nixnax 11:f58998c24f0b 215 }
nixnax 11:f58998c24f0b 216 sum = sum + (sum>>16);
nixnax 25:0b0450e1b08b 217 if (len&1) { ptr[len-1] = placeHolder; } // restore the last byte for odd lengths
nixnax 12:db0dc91f0231 218 return ~sum;
nixnax 11:f58998c24f0b 219 }
nixnax 11:f58998c24f0b 220
nixnax 11:f58998c24f0b 221 void headerCheckSum() {
nixnax 11:f58998c24f0b 222 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 223 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 224 int sum=0;
nixnax 11:f58998c24f0b 225
nixnax 11:f58998c24f0b 226 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 227 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 228 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 229 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 230 sum = sum + val;
nixnax 11:f58998c24f0b 231 }
nixnax 11:f58998c24f0b 232 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 233 sum = ~sum;
nixnax 11:f58998c24f0b 234 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 235 ppp.pkt.buf[15]= (sum );
nixnax 9:0992486d4a30 236 }
nixnax 9:0992486d4a30 237
nixnax 11:f58998c24f0b 238 void ICMPpacket() { // internet control message protocol
nixnax 12:db0dc91f0231 239 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 240 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 241 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 242 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 243 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 244 char * icmpSum = icmpType+2; // icmp checksum
nixnax 13:d882b8a042b4 245
nixnax 12:db0dc91f0231 246 #define ICMP_TYPE_PING_REQUEST 8
nixnax 12:db0dc91f0231 247 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 248 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 249 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 250 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 251 char * dstAdr = ipPkt+16;
nixnax 18:3e35de1bc877 252 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 18:3e35de1bc877 253 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 25:0b0450e1b08b 254 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 25:0b0450e1b08b 255 debug(("Ident %04x Sequence %04d ",icmpIdent,icmpSequence));
nixnax 11:f58998c24f0b 256 char src[4]; char dst[4];
nixnax 12:db0dc91f0231 257 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 258 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 259 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 260 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 261 char * chkSum = ipPkt+10;
nixnax 12:db0dc91f0231 262 chkSum[0]=0; chkSum[1]=0;
nixnax 12:db0dc91f0231 263 headerCheckSum(); // new ip header checksum
nixnax 12:db0dc91f0231 264 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 265 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 12:db0dc91f0231 266 icmpSum[0]=0; icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 267 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 16:cb0b80c24ba2 268 int sum = dataCheckSum( icmpType, icmpLength); // this checksum on icmp data portion
nixnax 12:db0dc91f0231 269 icmpSum[0]=sum>>8; icmpSum[1]=sum; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 270
nixnax 16:cb0b80c24ba2 271 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 272 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 273 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 25:0b0450e1b08b 274 for (int i=0; i<printSize; i++) { char ch = icmpData[i]; if (ch>31 && ch<127) { debug(("%c",ch)); } else { debug(("_")); }}
nixnax 25:0b0450e1b08b 275 debug(("\n"));
nixnax 25:0b0450e1b08b 276
nixnax 15:b0154c910143 277 sendFrame(); // reply to the ping
nixnax 25:0b0450e1b08b 278
nixnax 12:db0dc91f0231 279 } else {
nixnax 15:b0154c910143 280 debug(("ICMP type=%d \n", icmpType[0]));
nixnax 11:f58998c24f0b 281 }
nixnax 11:f58998c24f0b 282 }
nixnax 11:f58998c24f0b 283
nixnax 11:f58998c24f0b 284 void IGMPpacket() { // internet group management protocol
nixnax 15:b0154c910143 285 debug(("IGMP type=%d \n", ppp.pkt.buf[28]));
nixnax 11:f58998c24f0b 286 }
nixnax 11:f58998c24f0b 287
nixnax 26:11f4eb2663a7 288
nixnax 26:11f4eb2663a7 289 void dumpHeaderIP () {
nixnax 26:11f4eb2663a7 290 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 291 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 292 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 293 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 294 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 295 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 296 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 297 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 298 //char * fragment = ipPkt+6; // 14 bits
nixnax 26:11f4eb2663a7 299 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 300 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 301 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 302 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 303 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 304
nixnax 26:11f4eb2663a7 305 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 306 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 307 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 308 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 309 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 310 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 311 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 312 //int fragmentIP = ((fragment[0]&0x3f)<<8)|fragment[1];
nixnax 26:11f4eb2663a7 313 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 314 int protocolIP = protocol[0];
nixnax 26:11f4eb2663a7 315 int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 26:11f4eb2663a7 316 char srcIP [16]; snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 26:11f4eb2663a7 317 char dstIP [16]; snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 26:11f4eb2663a7 318 debug(("IP %s %s v%d h%d d%d e%d L%d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength));
nixnax 26:11f4eb2663a7 319 debug(("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP));
nixnax 26:11f4eb2663a7 320 }
nixnax 26:11f4eb2663a7 321
nixnax 26:11f4eb2663a7 322 void dumpHeaderTCP() {
nixnax 26:11f4eb2663a7 323 int ipHdrLen = (ppp.pkt.buf[4]&0xf)*4; // overall length of ip packet
nixnax 26:11f4eb2663a7 324
nixnax 26:11f4eb2663a7 325 char * s = ppp.pkt.buf+4+ipHdrLen; // start of tcp packet
nixnax 26:11f4eb2663a7 326 //char * srctcp = s + 0; // 2 bytes
nixnax 26:11f4eb2663a7 327 //char * dsttcp = s + 2; // 2 bytes
nixnax 26:11f4eb2663a7 328 char * seqtcp = s + 4; // 4 bytes
nixnax 26:11f4eb2663a7 329 char * acktcp = s + 8; // 4 bytes
nixnax 26:11f4eb2663a7 330 //char * offset = s + 12; // 4 bits
nixnax 26:11f4eb2663a7 331 char * flagbitstcp = s + 12; // 9 bits
nixnax 26:11f4eb2663a7 332 //char * winsizetcp = s + 14; // 2 bytes
nixnax 26:11f4eb2663a7 333 //char * checksumtcp = s + 16; // 2 bytes
nixnax 26:11f4eb2663a7 334 //char * urgentpointer = s + 18; // 2 bytes
nixnax 26:11f4eb2663a7 335
nixnax 26:11f4eb2663a7 336 //int srcPort = (srctcp[0]<<8)|srctcp[1];
nixnax 26:11f4eb2663a7 337 //int dstPort = (dsttcp[0]<<8)|dsttcp[1];
nixnax 26:11f4eb2663a7 338 int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 26:11f4eb2663a7 339 int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 26:11f4eb2663a7 340 //int tcpHdrSize = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 26:11f4eb2663a7 341 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 26:11f4eb2663a7 342 //int winsize = (winsizetcp[0]<<8)|winsizetcp[1];
nixnax 26:11f4eb2663a7 343 //int checkTCP = (checksumtcp[0]<<8)|checksumtcp[1];
nixnax 26:11f4eb2663a7 344 //int urgentTCP = (urgentpointer[0]<<8)|urgentpointer[1];
nixnax 26:11f4eb2663a7 345
nixnax 26:11f4eb2663a7 346 int idx = 0; char flagInfo [40];
nixnax 26:11f4eb2663a7 347 if (flags & (1<<0)) idx=snprintf(flagInfo+idx,40, "FIN "); if (flags & (1<<1)) idx=snprintf(flagInfo+idx,40, "SYN ");
nixnax 26:11f4eb2663a7 348 if (flags & (1<<2)) idx=snprintf(flagInfo+idx,40, "RST "); if (flags & (1<<3)) idx=snprintf(flagInfo+idx,40, "PSH ");
nixnax 26:11f4eb2663a7 349 if (flags & (1<<4)) idx=snprintf(flagInfo+idx,40, "ACK "); if (flags & (1<<5)) idx=snprintf(flagInfo+idx,40, "URG ");
nixnax 26:11f4eb2663a7 350 if (flags & (1<<6)) idx=snprintf(flagInfo+idx,40, "ECE "); if (flags & (1<<7)) idx=snprintf(flagInfo+idx,40, "CWR ");
nixnax 26:11f4eb2663a7 351 if (flags & (1<<8)) idx=snprintf(flagInfo+idx,40, "NS ");
nixnax 26:11f4eb2663a7 352
nixnax 26:11f4eb2663a7 353 debug(("Flag %s Seq %08x Ack %08x ", flagInfo, seq, ack));
nixnax 26:11f4eb2663a7 354
nixnax 10:74f8233f72c0 355 }
nixnax 10:74f8233f72c0 356
nixnax 26:11f4eb2663a7 357 void tcpHandler() {
nixnax 26:11f4eb2663a7 358
nixnax 26:11f4eb2663a7 359 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 360 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 361
nixnax 26:11f4eb2663a7 362 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 363 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 364 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 365 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 366 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 367 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 368
nixnax 26:11f4eb2663a7 369 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 370 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 371
nixnax 26:11f4eb2663a7 372 ident[0] = ppp.ident>>8; ident[1] = ppp.ident>>0; // stuff in our ident
nixnax 26:11f4eb2663a7 373
nixnax 26:11f4eb2663a7 374 char src[4]; char dst[4]; memcpy(src, srcAdr,4); memcpy(dst, dstAdr,4);
nixnax 26:11f4eb2663a7 375 memcpy(srcAdr, dst,4); memcpy(dstAdr, src,4); // swap ip address source/dest
nixnax 26:11f4eb2663a7 376 headercheck[0]=0; headercheck[1]=0; headerCheckSum(); // redo the tcp header checksum
nixnax 26:11f4eb2663a7 377
nixnax 26:11f4eb2663a7 378 headercheck[0]=0; headercheck[1]=0; headerCheckSum(); // redo the tcp header checksum
nixnax 26:11f4eb2663a7 379
nixnax 26:11f4eb2663a7 380 int ipHdrLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 26:11f4eb2663a7 381 char * s = ppp.pkt.buf+4+ipHdrLen; // start of tcp packet
nixnax 26:11f4eb2663a7 382 char * srctcp = s + 0; // 2 bytes
nixnax 26:11f4eb2663a7 383 char * dsttcp = s + 2; // 2 bytes
nixnax 26:11f4eb2663a7 384 char * flagbitstcp = s + 12; // 9 bits
nixnax 26:11f4eb2663a7 385 char * checksumtcp = s + 16; // 2 bytes
nixnax 26:11f4eb2663a7 386
nixnax 26:11f4eb2663a7 387 int tcpSize = packetLength - headerSizeIP;
nixnax 26:11f4eb2663a7 388 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 26:11f4eb2663a7 389
nixnax 26:11f4eb2663a7 390 int syncFound = 0;
nixnax 26:11f4eb2663a7 391 #define TCP_FLAG_SYN 2
nixnax 26:11f4eb2663a7 392 if ((flagsTCP & TCP_FLAG_SYN)!=0) syncFound=1;
nixnax 26:11f4eb2663a7 393
nixnax 26:11f4eb2663a7 394 #define TCP_FLAG_ACK (1<<4)
nixnax 26:11f4eb2663a7 395 flagbitstcp[1] = TCP_FLAG_ACK; // change any flag to an ACK
nixnax 26:11f4eb2663a7 396
nixnax 26:11f4eb2663a7 397 char psrc[2]; char pdst[2]; memcpy(psrc, srctcp,2); memcpy(pdst, dsttcp,2);
nixnax 26:11f4eb2663a7 398 memcpy(srctcp, pdst,2); memcpy(dsttcp, psrc,2); // swap ip port source/dest
nixnax 26:11f4eb2663a7 399
nixnax 26:11f4eb2663a7 400 char pseudoHeader[12]; int sum; char temp[12]; // for the terrible pseudoheader checksum
nixnax 26:11f4eb2663a7 401
nixnax 26:11f4eb2663a7 402 memcpy( pseudoHeader+0, srcAdr, 8); // source and destination addresses.
nixnax 26:11f4eb2663a7 403 pseudoHeader[8]=0; pseudoHeader[9]=protocol[0];
nixnax 26:11f4eb2663a7 404 pseudoHeader[10]=tcpSize>>8; pseudoHeader[11]=tcpSize;
nixnax 26:11f4eb2663a7 405 memcpy(temp, s-12, 12); // keep a copy
nixnax 26:11f4eb2663a7 406 memcpy( s-12, pseudoHeader, 12); // put the header on the tcp packet
nixnax 26:11f4eb2663a7 407 checksumtcp[0]=0; checksumtcp[1]=0;
nixnax 26:11f4eb2663a7 408 sum=dataCheckSum(s-12,tcpSize+12); // update TCP checksum
nixnax 26:11f4eb2663a7 409 checksumtcp[0]=sum>>8; checksumtcp[1]=sum;
nixnax 26:11f4eb2663a7 410 memcpy( s-12, temp, 12); // overwrite the pseudoheader
nixnax 26:11f4eb2663a7 411
nixnax 26:11f4eb2663a7 412 sendFrame(); // return the TCP packet
nixnax 26:11f4eb2663a7 413
nixnax 26:11f4eb2663a7 414 if (syncFound==0) return;
nixnax 26:11f4eb2663a7 415
nixnax 26:11f4eb2663a7 416 flagbitstcp[1] = TCP_FLAG_SYN; // change the ACK to our SYN
nixnax 26:11f4eb2663a7 417
nixnax 26:11f4eb2663a7 418 memcpy( pseudoHeader+0, srcAdr, 8); // source and destination addresses.
nixnax 26:11f4eb2663a7 419 pseudoHeader[8]=0; pseudoHeader[9]=protocol[0];
nixnax 26:11f4eb2663a7 420 pseudoHeader[10]=tcpSize>>8; pseudoHeader[11]=tcpSize;
nixnax 26:11f4eb2663a7 421 memcpy(temp, s-12, 12); // keep a copy
nixnax 26:11f4eb2663a7 422 memcpy( s-12, pseudoHeader, 12); // put the header on the tcp packet
nixnax 26:11f4eb2663a7 423 checksumtcp[0]=0; checksumtcp[1]=0;
nixnax 26:11f4eb2663a7 424 sum=dataCheckSum(s-12,tcpSize+12); // update TCP checksum
nixnax 26:11f4eb2663a7 425 checksumtcp[0]=sum>>8; checksumtcp[1]=sum;
nixnax 26:11f4eb2663a7 426 memcpy( s-12, temp, 12); // overwrite the pseudoheader
nixnax 26:11f4eb2663a7 427
nixnax 26:11f4eb2663a7 428 sendFrame(); // send our request as a response to a SYN
nixnax 26:11f4eb2663a7 429 }
nixnax 26:11f4eb2663a7 430
nixnax 26:11f4eb2663a7 431 void dumpDataTCP() {
nixnax 26:11f4eb2663a7 432 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 433 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 26:11f4eb2663a7 434 int tcpHeaderLen = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 26:11f4eb2663a7 435 int dataLen = ipPktLen - ipHeaderLen - tcpHeaderLen; // data is what's left after the two headers
nixnax 26:11f4eb2663a7 436 debug(("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, tcpHeaderLen, dataLen));
nixnax 26:11f4eb2663a7 437 }
nixnax 26:11f4eb2663a7 438
nixnax 26:11f4eb2663a7 439 void TCPpacket(){
nixnax 26:11f4eb2663a7 440 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 441 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 442 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 443 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 444 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 445 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 446 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 447 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 448 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 449 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 450 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 451 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 452 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 453
nixnax 26:11f4eb2663a7 454 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 455 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 456 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 457 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 458 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 459 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 460 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 461 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 462 int protocolIP = protocol[0];
nixnax 26:11f4eb2663a7 463 int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 26:11f4eb2663a7 464 char srcIP [16]; snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 26:11f4eb2663a7 465 char dstIP [16]; snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 26:11f4eb2663a7 466 debug(("IP %s %s v%d h%d d%d e%d L%d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength));
nixnax 26:11f4eb2663a7 467 debug(("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP));
nixnax 26:11f4eb2663a7 468 dumpHeaderTCP();
nixnax 26:11f4eb2663a7 469 dumpDataTCP();
nixnax 26:11f4eb2663a7 470 tcpHandler();
nixnax 11:f58998c24f0b 471 }
nixnax 11:f58998c24f0b 472
nixnax 26:11f4eb2663a7 473 void otherProtocol() { debug(("Other IP protocol")); }
nixnax 26:11f4eb2663a7 474
nixnax 10:74f8233f72c0 475 void IPframe() {
nixnax 10:74f8233f72c0 476 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 477 switch (protocol) {
nixnax 11:f58998c24f0b 478 case 1: ICMPpacket(); break;
nixnax 11:f58998c24f0b 479 case 2: IGMPpacket(); break;
nixnax 11:f58998c24f0b 480 case 17: UDPpacket(); break;
nixnax 11:f58998c24f0b 481 case 6: TCPpacket(); break;
nixnax 11:f58998c24f0b 482 default: otherProtocol();
nixnax 10:74f8233f72c0 483 }
nixnax 15:b0154c910143 484 //debug((("IP frame proto %3d len %4d %d.%d.%d.%d %d.%d.%d.%d\n", ppp.pkt.buf[13],(ppp.pkt.buf[6]<<8)+ppp.pkt.buf[7],ppp.pkt.buf[16],ppp.pkt.buf[17],ppp.pkt.buf[18],ppp.pkt.buf[19],ppp.pkt.buf[20],ppp.pkt.buf[21],ppp.pkt.buf[22],ppp.pkt.buf[23] );
nixnax 10:74f8233f72c0 485 }
nixnax 9:0992486d4a30 486
nixnax 9:0992486d4a30 487 void LCPconfReq() {
nixnax 15:b0154c910143 488 debug(("LCP Config "));
nixnax 9:0992486d4a30 489 if (ppp.pkt.buf[7] != 4) {
nixnax 11:f58998c24f0b 490 ppp.pkt.buf[4]=4; // allow only no options
nixnax 15:b0154c910143 491 debug(("Reject\n"));
nixnax 9:0992486d4a30 492 sendFrame();
nixnax 9:0992486d4a30 493 } else {
nixnax 9:0992486d4a30 494 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 15:b0154c910143 495 debug(("Ack\n"));
nixnax 9:0992486d4a30 496 sendFrame();
nixnax 15:b0154c910143 497 debug(("LCP Ask\n"));
nixnax 11:f58998c24f0b 498 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 499 sendFrame();
nixnax 9:0992486d4a30 500 }
nixnax 9:0992486d4a30 501 }
nixnax 9:0992486d4a30 502
nixnax 9:0992486d4a30 503 void LCPconfAck() {
nixnax 15:b0154c910143 504 debug(("LCP Ack\n"));
nixnax 9:0992486d4a30 505 }
nixnax 9:0992486d4a30 506
nixnax 9:0992486d4a30 507 void LCPend(){
nixnax 15:b0154c910143 508 debug(("LCP End\n"));
nixnax 12:db0dc91f0231 509 ppp.online=0; // start hunting for connect string again
nixnax 9:0992486d4a30 510 ppp.pkt.buf[4]=6;
nixnax 12:db0dc91f0231 511 sendFrame(); // acknowledge
nixnax 9:0992486d4a30 512 }
nixnax 9:0992486d4a30 513
nixnax 9:0992486d4a30 514 void LCPother(){
nixnax 15:b0154c910143 515 debug(("LCP Other\n"));
nixnax 12:db0dc91f0231 516 dumpFrame();
nixnax 9:0992486d4a30 517 }
nixnax 9:0992486d4a30 518
nixnax 9:0992486d4a30 519 void LCPframe(){
nixnax 9:0992486d4a30 520 int code = ppp.pkt.buf[4];
nixnax 9:0992486d4a30 521 switch (code) {
nixnax 12:db0dc91f0231 522 case 1: LCPconfReq(); break; // config request
nixnax 12:db0dc91f0231 523 case 2: LCPconfAck(); break; // config ack
nixnax 12:db0dc91f0231 524 case 5: LCPend(); break; // end connection
nixnax 12:db0dc91f0231 525 default: LCPother();
nixnax 9:0992486d4a30 526 }
nixnax 9:0992486d4a30 527 }
nixnax 9:0992486d4a30 528
nixnax 12:db0dc91f0231 529 void discardedFrame() {
nixnax 15:b0154c910143 530 debug(("Dropping frame %02x %02x %02x %02x\n", ppp.pkt.buf[0],ppp.pkt.buf[1],ppp.pkt.buf[2],ppp.pkt.buf[3]));
nixnax 9:0992486d4a30 531 }
nixnax 9:0992486d4a30 532
nixnax 9:0992486d4a30 533 void determinePacketType() {
nixnax 15:b0154c910143 534 if ( ppp.pkt.buf[0] != 0xff ) { debug(("byte0 != ff\n")); return;}
nixnax 15:b0154c910143 535 if ( ppp.pkt.buf[1] != 3 ) { debug(("byte1 != 3\n")); return;}
nixnax 15:b0154c910143 536 if ( ppp.pkt.buf[3] != 0x21 ) { debug(("byte2 != 21\n")); return;}
nixnax 9:0992486d4a30 537 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 538 switch (packetType) {
nixnax 12:db0dc91f0231 539 case 0xc0: LCPframe(); break; // link control
nixnax 12:db0dc91f0231 540 case 0x80: IPCPframe(); break; // IP control
nixnax 12:db0dc91f0231 541 case 0x00: IPframe(); break; // IP itself
nixnax 12:db0dc91f0231 542 default: discardedFrame();
nixnax 9:0992486d4a30 543 }
nixnax 9:0992486d4a30 544 }
nixnax 9:0992486d4a30 545
nixnax 9:0992486d4a30 546 void scanForConnectString() {
nixnax 9:0992486d4a30 547 if ( ppp.online==0 ) {
nixnax 15:b0154c910143 548 char * clientFound = strstr( (char *)rxbuf, "CLIENTCLIENT" ); // look for PC string
nixnax 9:0992486d4a30 549 if( clientFound ) {
nixnax 9:0992486d4a30 550 strcpy( clientFound, "FOUND!FOUND!" ); // overwrite so we don't get fixated
nixnax 9:0992486d4a30 551 pc.printf("CLIENTSERVER"); // respond to PC
nixnax 9:0992486d4a30 552 ppp.online=1; // we can stop looking for the string
nixnax 15:b0154c910143 553 debug(("Connect string found\n"));
nixnax 9:0992486d4a30 554 }
nixnax 9:0992486d4a30 555 }
nixnax 9:0992486d4a30 556 }
nixnax 9:0992486d4a30 557
nixnax 26:11f4eb2663a7 558 int myIdent = 0;
nixnax 26:11f4eb2663a7 559
nixnax 0:2cf4880c312a 560 int main()
nixnax 0:2cf4880c312a 561 {
nixnax 14:c65831c25aaa 562 pc.baud(115200); // USB virtual serial port
nixnax 15:b0154c910143 563 xx.baud(115200); // second serial port for debug(((((((( messages
nixnax 9:0992486d4a30 564 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 4:a469050d5b80 565
nixnax 9:0992486d4a30 566 pppInitStruct(); // initialize all the PPP properties
nixnax 4:a469050d5b80 567
nixnax 9:0992486d4a30 568 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 4:a469050d5b80 569
nixnax 9:0992486d4a30 570 int frameStartIndex, frameEndIndex; int frameBusy=0;
nixnax 4:a469050d5b80 571
nixnax 0:2cf4880c312a 572 while(1) {
nixnax 9:0992486d4a30 573 if ( ppp.online==0 ) scanForConnectString(); // try to connect
nixnax 22:00df34cd4d7e 574 while ( rxbufNotEmpty() ) {
nixnax 1:9e03798d4367 575 int rx = pc_getBuf();
nixnax 4:a469050d5b80 576 if (frameBusy) {
nixnax 4:a469050d5b80 577 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 578 frameBusy=0; // done gathering frame
nixnax 4:a469050d5b80 579 frameEndIndex=ppp.rx.tail-1; // remember where frame ends
nixnax 4:a469050d5b80 580 processFrame(frameStartIndex, frameEndIndex);
nixnax 4:a469050d5b80 581 }
nixnax 4:a469050d5b80 582 }
nixnax 4:a469050d5b80 583 else {
nixnax 4:a469050d5b80 584 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 585 frameBusy=1; // start gathering frame
nixnax 9:0992486d4a30 586 frameStartIndex=ppp.rx.tail; // remember where frame started
nixnax 4:a469050d5b80 587 }
nixnax 0:2cf4880c312a 588 }
nixnax 4:a469050d5b80 589 }
nixnax 7:ab147f5e97ac 590 }
nixnax 7:ab147f5e97ac 591 }