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@23:af88d429bed1, 2017-01-02 (annotated)

Committer:
nixnax
Date:
Mon Jan 02 18:22:51 2017 +0000
Revision:
23:af88d429bed1
Parent:
22:00df34cd4d7e
Child:
24:9f3db3bf7f9c
Fixed the bug for odd ICMP data block sizes

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 4:a469050d5b80 35 struct {
nixnax 20:5db9b77b38a6 36 char * buf;
nixnax 15:b0154c910143 37 volatile int head;
nixnax 20:5db9b77b38a6 38 volatile int tail;
nixnax 9:0992486d4a30 39 int total;
nixnax 4:a469050d5b80 40 } rx; // serial port buffer
nixnax 4:a469050d5b80 41 struct {
nixnax 6:fba4c2e817b8 42 int id;
nixnax 4:a469050d5b80 43 int len;
nixnax 4:a469050d5b80 44 int crc;
nixnax 4:a469050d5b80 45 char * buf;
nixnax 4:a469050d5b80 46 } pkt; // ppp buffer
nixnax 4:a469050d5b80 47 } ppp;
nixnax 0:2cf4880c312a 48
nixnax 9:0992486d4a30 49 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;}
nixnax 4:a469050d5b80 50
nixnax 4:a469050d5b80 51 int crcG; // frame check sequence (CRC) holder
nixnax 4:a469050d5b80 52 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 53 void crcReset(){crcG=0xffff;} // crc restart
nixnax 9:0992486d4a30 54 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 55
nixnax 0:2cf4880c312a 56 void rxHandler() // serial port receive interrupt handler
nixnax 0:2cf4880c312a 57 {
nixnax 17:4918c893d802 58 while ( pc.readable() ) {
nixnax 20:5db9b77b38a6 59 int hd = (ppp.rx.head+1)&(BUFLEN-1); // increment/wrap
nixnax 20:5db9b77b38a6 60 if ( hd == ppp.rx.tail ) break; // watch for buffer full
nixnax 17:4918c893d802 61 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 62 ppp.rx.head = hd; // update head pointer
nixnax 15:b0154c910143 63 }
nixnax 0:2cf4880c312a 64 }
nixnax 0:2cf4880c312a 65
nixnax 14:c65831c25aaa 66 int ledState=0;
nixnax 14:c65831c25aaa 67 void led1Toggle(){
nixnax 14:c65831c25aaa 68 ledState = ledState? 0 : 1;
nixnax 14:c65831c25aaa 69 led1 = ledState;
nixnax 14:c65831c25aaa 70 }
nixnax 14:c65831c25aaa 71
nixnax 22:00df34cd4d7e 72 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 73 {
nixnax 22:00df34cd4d7e 74 __disable_irq(); // critical section start
nixnax 22:00df34cd4d7e 75 int notEmpty = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 22:00df34cd4d7e 76 __enable_irq(); // critical section end
nixnax 22:00df34cd4d7e 77 return notEmpty;
nixnax 0:2cf4880c312a 78 }
nixnax 0:2cf4880c312a 79
nixnax 0:2cf4880c312a 80 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 81 {
nixnax 22:00df34cd4d7e 82 if ( rxbufNotEmpty() ) {
nixnax 4:a469050d5b80 83 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 20:5db9b77b38a6 84 __disable_irq(); // critical section start
nixnax 22:00df34cd4d7e 85 ppp.rx.tail=(ppp.rx.tail+1)&(BUFLEN-1);
nixnax 20:5db9b77b38a6 86 __enable_irq(); // critical section end
nixnax 0:2cf4880c312a 87 return x;
nixnax 20:5db9b77b38a6 88 } else return -1;
nixnax 0:2cf4880c312a 89 }
nixnax 0:2cf4880c312a 90
nixnax 4:a469050d5b80 91 void scanForConnectString(); // scan for connect attempts from pc
nixnax 1:9e03798d4367 92
nixnax 9:0992486d4a30 93 void processFrame(int start, int end) { // process received frame
nixnax 14:c65831c25aaa 94 led1Toggle(); // change led1 state when frames are received
nixnax 15:b0154c910143 95 if(start==end) { pc.putc(0x7e); return; }
nixnax 9:0992486d4a30 96 crcReset();
nixnax 9:0992486d4a30 97 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 98 ppp.pkt.len=0;
nixnax 9:0992486d4a30 99 int unstuff=0;
nixnax 17:4918c893d802 100 int idx = start;
nixnax 17:4918c893d802 101 while(1) {
nixnax 9:0992486d4a30 102 if (unstuff==0) {
nixnax 17:4918c893d802 103 if (rxbuf[idx]==0x7d) unstuff=1;
nixnax 17:4918c893d802 104 else { *dest = rxbuf[idx]; ppp.pkt.len++; dest++; crcDo(rxbuf[idx]); }
nixnax 12:db0dc91f0231 105 } else { // unstuff
nixnax 17:4918c893d802 106 *dest = rxbuf[idx]^0x20; ppp.pkt.len++; dest++; crcDo(rxbuf[idx]^0x20);
nixnax 9:0992486d4a30 107 unstuff=0;
nixnax 9:0992486d4a30 108 }
nixnax 17:4918c893d802 109 idx = (idx+1) & (BUFLEN-1);
nixnax 17:4918c893d802 110 if (idx == end) break;
nixnax 9:0992486d4a30 111 }
nixnax 9:0992486d4a30 112 ppp.pkt.crc = crcG & 0xffff;
nixnax 9:0992486d4a30 113 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 114 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 115 determinePacketType();
nixnax 12:db0dc91f0231 116 } else { // crc error
nixnax 15:b0154c910143 117 debug(("CRC is %x Len is %d\n",ppp.pkt.crc,ppp.pkt.len));
nixnax 15:b0154c910143 118 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 15:b0154c910143 119 debug(("\n"));
nixnax 9:0992486d4a30 120 }
nixnax 9:0992486d4a30 121 }
nixnax 9:0992486d4a30 122
nixnax 11:f58998c24f0b 123 void dumpFrame() {
nixnax 16:cb0b80c24ba2 124 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 16:cb0b80c24ba2 125 debug((" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len));
nixnax 16:cb0b80c24ba2 126 }
nixnax 16:cb0b80c24ba2 127
nixnax 16:cb0b80c24ba2 128 void hdlcPut(int ch) { // do hdlc handling of special (flag) characters
nixnax 16:cb0b80c24ba2 129 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) { pc.putc(0x7d); pc.putc(ch^0x20); } else { pc.putc(ch); }
nixnax 11:f58998c24f0b 130 }
nixnax 9:0992486d4a30 131
nixnax 9:0992486d4a30 132 void sendFrame(){
nixnax 17:4918c893d802 133 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 134 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 135 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 136 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 16:cb0b80c24ba2 137 for(int i=0;i<ppp.pkt.len;i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 138 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 139 }
nixnax 9:0992486d4a30 140
nixnax 9:0992486d4a30 141 void ipRequestHandler(){
nixnax 15:b0154c910143 142 debug(("IPCP Conf "));
nixnax 9:0992486d4a30 143 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 15:b0154c910143 144 debug(("Rej\n")); // reject if any options are requested
nixnax 9:0992486d4a30 145 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 146 sendFrame();
nixnax 9:0992486d4a30 147 } else {
nixnax 15:b0154c910143 148 debug(("Ack\n"));
nixnax 9:0992486d4a30 149 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 150 sendFrame(); // acknowledge
nixnax 15:b0154c910143 151 debug(("IPCP Ask\n"));
nixnax 9:0992486d4a30 152 // send our own request now
nixnax 12:db0dc91f0231 153 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 154 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 155 sendFrame(); // this is our request
nixnax 9:0992486d4a30 156 }
nixnax 9:0992486d4a30 157 }
nixnax 9:0992486d4a30 158
nixnax 15:b0154c910143 159 void ipAckHandler(){ debug(("IPCP Grant\n")); }
nixnax 9:0992486d4a30 160
nixnax 15:b0154c910143 161 void ipNackHandler(){ debug(("IPCP Nack\n")); }
nixnax 9:0992486d4a30 162
nixnax 15:b0154c910143 163 void ipDefaultHandler(){ debug(("IPCP Other\n")); }
nixnax 9:0992486d4a30 164
nixnax 9:0992486d4a30 165 void IPCPframe() {
nixnax 9:0992486d4a30 166 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 167 switch (code) {
nixnax 9:0992486d4a30 168 case 1: ipRequestHandler(); break;
nixnax 9:0992486d4a30 169 case 2: ipAckHandler(); break;
nixnax 9:0992486d4a30 170 case 3: ipNackHandler(); break;
nixnax 9:0992486d4a30 171 default: ipDefaultHandler();
nixnax 9:0992486d4a30 172 }
nixnax 9:0992486d4a30 173 }
nixnax 9:0992486d4a30 174
nixnax 10:74f8233f72c0 175 void UDPpacket() {
nixnax 12:db0dc91f0231 176 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 177 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 178 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 12:db0dc91f0231 179 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 180 char * udpDst = udpBlock+2; // destination port
nixnax 12:db0dc91f0231 181 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 182 char * udpInf = udpBlock+8; // actual start of info
nixnax 12:db0dc91f0231 183 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 184 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 185 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 186 char * dstIP = udpPkt+16; // udp dst addr
nixnax 12:db0dc91f0231 187 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 188 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 15:b0154c910143 189 debug(("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort));
nixnax 15:b0154c910143 190 debug(("%d.%d.%d.%d:%d ", dstIP[1],dstIP[1],dstIP[1],dstIP[1],dstPort));
nixnax 15:b0154c910143 191 debug(("Len %d ", udpLength));
nixnax 13:d882b8a042b4 192 int printSize = udpLength; if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 16:cb0b80c24ba2 193 for (int i=0; i<printSize; i++) { char ch = udpInf[i]; if (ch>31 && ch<127) { debug(("%c", ch)); } else { debug(("_")); } }
nixnax 15:b0154c910143 194 debug(("\n"));
nixnax 12:db0dc91f0231 195 }
nixnax 11:f58998c24f0b 196
nixnax 11:f58998c24f0b 197 int dataCheckSum(char * ptr, int len) {
nixnax 23:af88d429bed1 198 int sum=0; int placeHolder;
nixnax 23:af88d429bed1 199 if (len&1) { placeHolder = ptr[len-1]; ptr[len-1]=0; } // case where length is odd
nixnax 11:f58998c24f0b 200 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 201 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 202 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 203 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 204 sum = sum + val;
nixnax 11:f58998c24f0b 205 }
nixnax 11:f58998c24f0b 206 sum = sum + (sum>>16);
nixnax 23:af88d429bed1 207 if (len&1) { ptr[len-1] = placeHolder; } // for odd lengths restore the last byte
nixnax 12:db0dc91f0231 208 return ~sum;
nixnax 11:f58998c24f0b 209 }
nixnax 11:f58998c24f0b 210
nixnax 11:f58998c24f0b 211 void headerCheckSum() {
nixnax 11:f58998c24f0b 212 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 213 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 214 int sum=0;
nixnax 11:f58998c24f0b 215
nixnax 11:f58998c24f0b 216 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 217 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 218 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 219 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 220 sum = sum + val;
nixnax 11:f58998c24f0b 221 }
nixnax 11:f58998c24f0b 222 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 223 sum = ~sum;
nixnax 11:f58998c24f0b 224 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 225 ppp.pkt.buf[15]= (sum );
nixnax 9:0992486d4a30 226 }
nixnax 9:0992486d4a30 227
nixnax 11:f58998c24f0b 228 void ICMPpacket() { // internet control message protocol
nixnax 12:db0dc91f0231 229 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 230 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 231 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 232 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 233 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 234 char * icmpSum = icmpType+2; // icmp checksum
nixnax 13:d882b8a042b4 235
nixnax 12:db0dc91f0231 236 #define ICMP_TYPE_PING_REQUEST 8
nixnax 12:db0dc91f0231 237 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 238 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 239 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 240 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 241 char * dstAdr = ipPkt+16;
nixnax 18:3e35de1bc877 242 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 18:3e35de1bc877 243 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 18:3e35de1bc877 244 debug(("ICMP PING %d.%d.%d.%d %d.%d.%d.%d Ident %04x Sequence %04d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3],icmpIdent,icmpSequence));
nixnax 11:f58998c24f0b 245 char src[4]; char dst[4];
nixnax 12:db0dc91f0231 246 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 247 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 248 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 249 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 250 char * chkSum = ipPkt+10;
nixnax 12:db0dc91f0231 251 chkSum[0]=0; chkSum[1]=0;
nixnax 12:db0dc91f0231 252 headerCheckSum(); // new ip header checksum
nixnax 12:db0dc91f0231 253 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 254 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 12:db0dc91f0231 255 icmpSum[0]=0; icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 256 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 16:cb0b80c24ba2 257 int sum = dataCheckSum( icmpType, icmpLength); // this checksum on icmp data portion
nixnax 12:db0dc91f0231 258 icmpSum[0]=sum>>8; icmpSum[1]=sum; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 259
nixnax 16:cb0b80c24ba2 260 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 23:af88d429bed1 261 debug (("DS %d ", printSize));
nixnax 13:d882b8a042b4 262 char * icmpData = icmpType+8; // the actual data is after the header
nixnax 15:b0154c910143 263 if (printSize > 10) printSize = 10; // print only first 20 characters
nixnax 18:3e35de1bc877 264 for (int i=0; i<printSize; i++) { char ch = icmpData[i]; if (ch>31 && ch<127) { debug(("%c",ch)); } else { debug(("%c",'_')); }}
nixnax 18:3e35de1bc877 265 debug(("%c",'\n'));
nixnax 15:b0154c910143 266 sendFrame(); // reply to the ping
nixnax 23:af88d429bed1 267 dumpFrame();
nixnax 12:db0dc91f0231 268 } else {
nixnax 15:b0154c910143 269 debug(("ICMP type=%d \n", icmpType[0]));
nixnax 11:f58998c24f0b 270 }
nixnax 11:f58998c24f0b 271 }
nixnax 11:f58998c24f0b 272
nixnax 11:f58998c24f0b 273 void IGMPpacket() { // internet group management protocol
nixnax 15:b0154c910143 274 debug(("IGMP type=%d \n", ppp.pkt.buf[28]));
nixnax 11:f58998c24f0b 275 }
nixnax 11:f58998c24f0b 276
nixnax 11:f58998c24f0b 277 void TCPpacket() {
nixnax 15:b0154c910143 278 debug(("TCP\n"));
nixnax 10:74f8233f72c0 279 /*
nixnax 11:f58998c24f0b 280 switch (protocol) {
nixnax 11:f58998c24f0b 281 case 2: TCPsyn(); break;
nixnax 11:f58998c24f0b 282 case 17: TCPack(); break;
nixnax 11:f58998c24f0b 283 case 6: TCPpacket(); break;
nixnax 15:b0154c910143 284 default: debug(((( "Other \n");
nixnax 11:f58998c24f0b 285 }
nixnax 10:74f8233f72c0 286 */
nixnax 10:74f8233f72c0 287 }
nixnax 10:74f8233f72c0 288
nixnax 11:f58998c24f0b 289 void otherProtocol() {
nixnax 15:b0154c910143 290 debug(("Other IP protocol"));
nixnax 11:f58998c24f0b 291 }
nixnax 11:f58998c24f0b 292
nixnax 10:74f8233f72c0 293 void IPframe() {
nixnax 10:74f8233f72c0 294 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 295 switch (protocol) {
nixnax 11:f58998c24f0b 296 case 1: ICMPpacket(); break;
nixnax 11:f58998c24f0b 297 case 2: IGMPpacket(); break;
nixnax 11:f58998c24f0b 298 case 17: UDPpacket(); break;
nixnax 11:f58998c24f0b 299 case 6: TCPpacket(); break;
nixnax 11:f58998c24f0b 300 default: otherProtocol();
nixnax 10:74f8233f72c0 301 }
nixnax 15:b0154c910143 302 //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 303 }
nixnax 9:0992486d4a30 304
nixnax 9:0992486d4a30 305 void LCPconfReq() {
nixnax 15:b0154c910143 306 debug(("LCP Config "));
nixnax 9:0992486d4a30 307 if (ppp.pkt.buf[7] != 4) {
nixnax 11:f58998c24f0b 308 ppp.pkt.buf[4]=4; // allow only no options
nixnax 15:b0154c910143 309 debug(("Reject\n"));
nixnax 9:0992486d4a30 310 sendFrame();
nixnax 9:0992486d4a30 311 } else {
nixnax 9:0992486d4a30 312 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 15:b0154c910143 313 debug(("Ack\n"));
nixnax 9:0992486d4a30 314 sendFrame();
nixnax 15:b0154c910143 315 debug(("LCP Ask\n"));
nixnax 11:f58998c24f0b 316 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 317 sendFrame();
nixnax 9:0992486d4a30 318 }
nixnax 9:0992486d4a30 319 }
nixnax 9:0992486d4a30 320
nixnax 9:0992486d4a30 321 void LCPconfAck() {
nixnax 15:b0154c910143 322 debug(("LCP Ack\n"));
nixnax 9:0992486d4a30 323 }
nixnax 9:0992486d4a30 324
nixnax 9:0992486d4a30 325 void LCPend(){
nixnax 15:b0154c910143 326 debug(("LCP End\n"));
nixnax 12:db0dc91f0231 327 ppp.online=0; // start hunting for connect string again
nixnax 9:0992486d4a30 328 ppp.pkt.buf[4]=6;
nixnax 12:db0dc91f0231 329 sendFrame(); // acknowledge
nixnax 9:0992486d4a30 330 }
nixnax 9:0992486d4a30 331
nixnax 9:0992486d4a30 332 void LCPother(){
nixnax 15:b0154c910143 333 debug(("LCP Other\n"));
nixnax 12:db0dc91f0231 334 dumpFrame();
nixnax 9:0992486d4a30 335 }
nixnax 9:0992486d4a30 336
nixnax 9:0992486d4a30 337 void LCPframe(){
nixnax 9:0992486d4a30 338 int code = ppp.pkt.buf[4];
nixnax 9:0992486d4a30 339 switch (code) {
nixnax 12:db0dc91f0231 340 case 1: LCPconfReq(); break; // config request
nixnax 12:db0dc91f0231 341 case 2: LCPconfAck(); break; // config ack
nixnax 12:db0dc91f0231 342 case 5: LCPend(); break; // end connection
nixnax 12:db0dc91f0231 343 default: LCPother();
nixnax 9:0992486d4a30 344 }
nixnax 9:0992486d4a30 345 }
nixnax 9:0992486d4a30 346
nixnax 12:db0dc91f0231 347 void discardedFrame() {
nixnax 15:b0154c910143 348 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 349 }
nixnax 9:0992486d4a30 350
nixnax 9:0992486d4a30 351 void determinePacketType() {
nixnax 15:b0154c910143 352 if ( ppp.pkt.buf[0] != 0xff ) { debug(("byte0 != ff\n")); return;}
nixnax 15:b0154c910143 353 if ( ppp.pkt.buf[1] != 3 ) { debug(("byte1 != 3\n")); return;}
nixnax 15:b0154c910143 354 if ( ppp.pkt.buf[3] != 0x21 ) { debug(("byte2 != 21\n")); return;}
nixnax 9:0992486d4a30 355 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 356 switch (packetType) {
nixnax 12:db0dc91f0231 357 case 0xc0: LCPframe(); break; // link control
nixnax 12:db0dc91f0231 358 case 0x80: IPCPframe(); break; // IP control
nixnax 12:db0dc91f0231 359 case 0x00: IPframe(); break; // IP itself
nixnax 12:db0dc91f0231 360 default: discardedFrame();
nixnax 9:0992486d4a30 361 }
nixnax 9:0992486d4a30 362 }
nixnax 9:0992486d4a30 363
nixnax 9:0992486d4a30 364 void scanForConnectString() {
nixnax 9:0992486d4a30 365 if ( ppp.online==0 ) {
nixnax 15:b0154c910143 366 char * clientFound = strstr( (char *)rxbuf, "CLIENTCLIENT" ); // look for PC string
nixnax 9:0992486d4a30 367 if( clientFound ) {
nixnax 9:0992486d4a30 368 strcpy( clientFound, "FOUND!FOUND!" ); // overwrite so we don't get fixated
nixnax 9:0992486d4a30 369 pc.printf("CLIENTSERVER"); // respond to PC
nixnax 9:0992486d4a30 370 ppp.online=1; // we can stop looking for the string
nixnax 15:b0154c910143 371 debug(("Connect string found\n"));
nixnax 9:0992486d4a30 372 }
nixnax 9:0992486d4a30 373 }
nixnax 9:0992486d4a30 374 }
nixnax 9:0992486d4a30 375
nixnax 0:2cf4880c312a 376 int main()
nixnax 0:2cf4880c312a 377 {
nixnax 14:c65831c25aaa 378 pc.baud(115200); // USB virtual serial port
nixnax 15:b0154c910143 379 xx.baud(115200); // second serial port for debug(((((((( messages
nixnax 9:0992486d4a30 380 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 4:a469050d5b80 381
nixnax 9:0992486d4a30 382 pppInitStruct(); // initialize all the PPP properties
nixnax 4:a469050d5b80 383
nixnax 9:0992486d4a30 384 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 4:a469050d5b80 385
nixnax 9:0992486d4a30 386 int frameStartIndex, frameEndIndex; int frameBusy=0;
nixnax 4:a469050d5b80 387
nixnax 0:2cf4880c312a 388 while(1) {
nixnax 9:0992486d4a30 389 if ( ppp.online==0 ) scanForConnectString(); // try to connect
nixnax 22:00df34cd4d7e 390 while ( rxbufNotEmpty() ) {
nixnax 1:9e03798d4367 391 int rx = pc_getBuf();
nixnax 4:a469050d5b80 392 if (frameBusy) {
nixnax 4:a469050d5b80 393 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 394 frameBusy=0; // done gathering frame
nixnax 4:a469050d5b80 395 frameEndIndex=ppp.rx.tail-1; // remember where frame ends
nixnax 4:a469050d5b80 396 processFrame(frameStartIndex, frameEndIndex);
nixnax 4:a469050d5b80 397 }
nixnax 4:a469050d5b80 398 }
nixnax 4:a469050d5b80 399 else {
nixnax 4:a469050d5b80 400 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 401 frameBusy=1; // start gathering frame
nixnax 9:0992486d4a30 402 frameStartIndex=ppp.rx.tail; // remember where frame started
nixnax 4:a469050d5b80 403 }
nixnax 0:2cf4880c312a 404 }
nixnax 4:a469050d5b80 405 }
nixnax 7:ab147f5e97ac 406 }
nixnax 7:ab147f5e97ac 407 }