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@16:cb0b80c24ba2, 2017-01-01 (annotated)

Committer:
nixnax
Date:
Sun Jan 01 20:34:59 2017 +0000
Revision:
16:cb0b80c24ba2
Parent:
15:b0154c910143
Child:
17:4918c893d802
Fixed 7D bug in hdlcPut

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 6:fba4c2e817b8 12 // http://atari.kensclassics.org/wcomlog.htm
nixnax 6:fba4c2e817b8 13 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 6:fba4c2e817b8 14 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
nixnax 9:0992486d4a30 15 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 6:fba4c2e817b8 16
nixnax 6:fba4c2e817b8 17 Serial pc(USBTX, USBRX); // The USB com port - Set this up as a Dial-Up Modem on your pc
nixnax 15:b0154c910143 18 Serial xx(PC_10, PC_11); // debug((((( port - use an additional USB serial port to monitor this
nixnax 0:2cf4880c312a 19
nixnax 16:cb0b80c24ba2 20 #define debug(x) xx.printf x
nixnax 9:0992486d4a30 21
nixnax 4:a469050d5b80 22 DigitalOut led1(LED1);
nixnax 4:a469050d5b80 23
nixnax 4:a469050d5b80 24 #define FRAME_7E (0x7e)
nixnax 16:cb0b80c24ba2 25 #define BUFLEN (1<<15)
nixnax 15:b0154c910143 26 volatile char rxbuf[BUFLEN];
nixnax 4:a469050d5b80 27 char frbuf[3000]; // buffer for ppp frame
nixnax 0:2cf4880c312a 28
nixnax 4:a469050d5b80 29 struct {
nixnax 4:a469050d5b80 30 int online;
nixnax 4:a469050d5b80 31 struct {
nixnax 15:b0154c910143 32 volatile char * buf;
nixnax 15:b0154c910143 33 volatile int head;
nixnax 4:a469050d5b80 34 int tail;
nixnax 9:0992486d4a30 35 int total;
nixnax 4:a469050d5b80 36 } rx; // serial port buffer
nixnax 4:a469050d5b80 37 struct {
nixnax 6:fba4c2e817b8 38 int id;
nixnax 4:a469050d5b80 39 int len;
nixnax 4:a469050d5b80 40 int crc;
nixnax 4:a469050d5b80 41 char * buf;
nixnax 4:a469050d5b80 42 } pkt; // ppp buffer
nixnax 4:a469050d5b80 43 } ppp;
nixnax 0:2cf4880c312a 44
nixnax 9:0992486d4a30 45 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 46
nixnax 4:a469050d5b80 47 int crcG; // frame check sequence (CRC) holder
nixnax 4:a469050d5b80 48 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 49 void crcReset(){crcG=0xffff;} // crc restart
nixnax 9:0992486d4a30 50 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 51
nixnax 0:2cf4880c312a 52 void rxHandler() // serial port receive interrupt handler
nixnax 0:2cf4880c312a 53 {
nixnax 16:cb0b80c24ba2 54 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in buffer
nixnax 16:cb0b80c24ba2 55 __disable_irq();
nixnax 15:b0154c910143 56 int next = (ppp.rx.head+1)&(BUFLEN-1);
nixnax 15:b0154c910143 57 if (next != ppp.rx.tail) {
nixnax 15:b0154c910143 58 ppp.rx.head=next;
nixnax 15:b0154c910143 59 //ppp.rx.total++;
nixnax 15:b0154c910143 60 __enable_irq();
nixnax 15:b0154c910143 61 }
nixnax 0:2cf4880c312a 62 }
nixnax 0:2cf4880c312a 63
nixnax 14:c65831c25aaa 64 int ledState=0;
nixnax 14:c65831c25aaa 65 void led1Toggle(){
nixnax 14:c65831c25aaa 66 ledState = ledState? 0 : 1;
nixnax 14:c65831c25aaa 67 led1 = ledState;
nixnax 14:c65831c25aaa 68 }
nixnax 14:c65831c25aaa 69
nixnax 0:2cf4880c312a 70 int pc_readable() // check if buffer has data
nixnax 0:2cf4880c312a 71 {
nixnax 4:a469050d5b80 72 return (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 0:2cf4880c312a 73 }
nixnax 0:2cf4880c312a 74
nixnax 0:2cf4880c312a 75 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 76 {
nixnax 15:b0154c910143 77 if (ppp.rx.head!=ppp.rx.tail) {
nixnax 4:a469050d5b80 78 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 4:a469050d5b80 79 ppp.rx.tail=(ppp.rx.tail+1)&(BUFLEN-1);
nixnax 0:2cf4880c312a 80 return x;
nixnax 0:2cf4880c312a 81 }
nixnax 0:2cf4880c312a 82 return -1;
nixnax 0:2cf4880c312a 83 }
nixnax 0:2cf4880c312a 84
nixnax 4:a469050d5b80 85 void scanForConnectString(); // scan for connect attempts from pc
nixnax 1:9e03798d4367 86
nixnax 9:0992486d4a30 87 void processFrame(int start, int end) { // process received frame
nixnax 14:c65831c25aaa 88 led1Toggle(); // change led1 state when frames are received
nixnax 15:b0154c910143 89 if(start==end) { pc.putc(0x7e); return; }
nixnax 9:0992486d4a30 90 crcReset();
nixnax 9:0992486d4a30 91 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 92 ppp.pkt.len=0;
nixnax 9:0992486d4a30 93 int unstuff=0;
nixnax 9:0992486d4a30 94 for (int i=start; i<end; i++) {
nixnax 9:0992486d4a30 95 if (unstuff==0) {
nixnax 9:0992486d4a30 96 if (rxbuf[i]==0x7d) unstuff=1;
nixnax 16:cb0b80c24ba2 97 else { *dest = rxbuf[i]; ppp.pkt.len++; dest++; crcDo(rxbuf[i]); }
nixnax 12:db0dc91f0231 98 } else { // unstuff
nixnax 16:cb0b80c24ba2 99 *dest = rxbuf[i]^0x20; ppp.pkt.len++; dest++; crcDo((int)rxbuf[i]^0x20);
nixnax 9:0992486d4a30 100 unstuff=0;
nixnax 9:0992486d4a30 101 }
nixnax 9:0992486d4a30 102 }
nixnax 9:0992486d4a30 103 ppp.pkt.crc = crcG & 0xffff;
nixnax 9:0992486d4a30 104 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 105 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 106 determinePacketType();
nixnax 12:db0dc91f0231 107 } else { // crc error
nixnax 15:b0154c910143 108 debug(("CRC is %x Len is %d\n",ppp.pkt.crc,ppp.pkt.len));
nixnax 15:b0154c910143 109 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 15:b0154c910143 110 debug(("\n"));
nixnax 9:0992486d4a30 111 }
nixnax 9:0992486d4a30 112 }
nixnax 9:0992486d4a30 113
nixnax 11:f58998c24f0b 114 void dumpFrame() {
nixnax 16:cb0b80c24ba2 115 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 16:cb0b80c24ba2 116 debug((" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len));
nixnax 16:cb0b80c24ba2 117 }
nixnax 16:cb0b80c24ba2 118
nixnax 16:cb0b80c24ba2 119 void hdlcPut(int ch) { // do hdlc handling of special (flag) characters
nixnax 16:cb0b80c24ba2 120 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) { pc.putc(0x7d); pc.putc(ch^0x20); } else { pc.putc(ch); }
nixnax 11:f58998c24f0b 121 }
nixnax 9:0992486d4a30 122
nixnax 9:0992486d4a30 123 void sendFrame(){
nixnax 16:cb0b80c24ba2 124 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // calculate crc
nixnax 12:db0dc91f0231 125 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 126 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 127 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 16:cb0b80c24ba2 128 for(int i=0;i<ppp.pkt.len;i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 129 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 130 }
nixnax 9:0992486d4a30 131
nixnax 9:0992486d4a30 132 void ipRequestHandler(){
nixnax 15:b0154c910143 133 debug(("IPCP Conf "));
nixnax 9:0992486d4a30 134 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 15:b0154c910143 135 debug(("Rej\n")); // reject if any options are requested
nixnax 9:0992486d4a30 136 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 137 sendFrame();
nixnax 9:0992486d4a30 138 } else {
nixnax 15:b0154c910143 139 debug(("Ack\n"));
nixnax 9:0992486d4a30 140 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 141 sendFrame(); // acknowledge
nixnax 15:b0154c910143 142 debug(("IPCP Ask\n"));
nixnax 9:0992486d4a30 143 // send our own request now
nixnax 12:db0dc91f0231 144 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 145 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 146 sendFrame(); // this is our request
nixnax 9:0992486d4a30 147 }
nixnax 9:0992486d4a30 148 }
nixnax 9:0992486d4a30 149
nixnax 15:b0154c910143 150 void ipAckHandler(){ debug(("IPCP Grant\n")); }
nixnax 9:0992486d4a30 151
nixnax 15:b0154c910143 152 void ipNackHandler(){ debug(("IPCP Nack\n")); }
nixnax 9:0992486d4a30 153
nixnax 15:b0154c910143 154 void ipDefaultHandler(){ debug(("IPCP Other\n")); }
nixnax 9:0992486d4a30 155
nixnax 9:0992486d4a30 156 void IPCPframe() {
nixnax 9:0992486d4a30 157 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 158 switch (code) {
nixnax 9:0992486d4a30 159 case 1: ipRequestHandler(); break;
nixnax 9:0992486d4a30 160 case 2: ipAckHandler(); break;
nixnax 9:0992486d4a30 161 case 3: ipNackHandler(); break;
nixnax 9:0992486d4a30 162 default: ipDefaultHandler();
nixnax 9:0992486d4a30 163 }
nixnax 9:0992486d4a30 164 }
nixnax 9:0992486d4a30 165
nixnax 10:74f8233f72c0 166 void UDPpacket() {
nixnax 12:db0dc91f0231 167 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 12:db0dc91f0231 168 //char * pktLen = udpPkt+2; // total packet length
nixnax 16:cb0b80c24ba2 169 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 170 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 12:db0dc91f0231 171 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 172 char * udpDst = udpBlock+2; // destination port
nixnax 12:db0dc91f0231 173 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 174 char * udpInf = udpBlock+8; // actual start of info
nixnax 12:db0dc91f0231 175 //char * udpSum = udpBlock+6; // udp checksum
nixnax 12:db0dc91f0231 176 //int packetLength = (pktLen[0]<<8) | pktLen[1]; // udp total packet length
nixnax 12:db0dc91f0231 177 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 178 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 179 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 180 char * dstIP = udpPkt+16; // udp dst addr
nixnax 12:db0dc91f0231 181 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 182 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 15:b0154c910143 183 debug(("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort));
nixnax 15:b0154c910143 184 debug(("%d.%d.%d.%d:%d ", dstIP[1],dstIP[1],dstIP[1],dstIP[1],dstPort));
nixnax 15:b0154c910143 185 debug(("Len %d ", udpLength));
nixnax 13:d882b8a042b4 186 int printSize = udpLength; if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 16:cb0b80c24ba2 187 for (int i=0; i<printSize; i++) { char ch = udpInf[i]; if (ch>31 && ch<127) { debug(("%c", ch)); } else { debug(("_")); } }
nixnax 15:b0154c910143 188 debug(("\n"));
nixnax 12:db0dc91f0231 189 }
nixnax 11:f58998c24f0b 190
nixnax 11:f58998c24f0b 191 int dataCheckSum(char * ptr, int len) {
nixnax 11:f58998c24f0b 192 int sum=0;
nixnax 11:f58998c24f0b 193 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 194 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 195 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 196 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 197 sum = sum + val;
nixnax 11:f58998c24f0b 198 }
nixnax 11:f58998c24f0b 199 sum = sum + (sum>>16);
nixnax 12:db0dc91f0231 200 return ~sum;
nixnax 11:f58998c24f0b 201 }
nixnax 11:f58998c24f0b 202
nixnax 11:f58998c24f0b 203 void headerCheckSum() {
nixnax 11:f58998c24f0b 204 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 205 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 206 int sum=0;
nixnax 11:f58998c24f0b 207
nixnax 11:f58998c24f0b 208 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 209 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 210 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 211 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 212 sum = sum + val;
nixnax 11:f58998c24f0b 213 }
nixnax 11:f58998c24f0b 214 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 215 sum = ~sum;
nixnax 11:f58998c24f0b 216 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 217 ppp.pkt.buf[15]= (sum );
nixnax 9:0992486d4a30 218 }
nixnax 9:0992486d4a30 219
nixnax 11:f58998c24f0b 220 void ICMPpacket() { // internet control message protocol
nixnax 12:db0dc91f0231 221 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 222 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 223 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 224 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 225 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 226 char * icmpSum = icmpType+2; // icmp checksum
nixnax 13:d882b8a042b4 227
nixnax 12:db0dc91f0231 228 #define ICMP_TYPE_PING_REQUEST 8
nixnax 12:db0dc91f0231 229 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 230 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 231 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 232 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 233 char * dstAdr = ipPkt+16;
nixnax 15:b0154c910143 234 debug(("ICMP PING %d.%d.%d.%d %d.%d.%d.%d Head %04d Tail=%04d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3],ppp.rx.head,ppp.rx.tail));
nixnax 11:f58998c24f0b 235 char src[4]; char dst[4];
nixnax 12:db0dc91f0231 236 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 237 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 238 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 239 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 240 char * chkSum = ipPkt+10;
nixnax 12:db0dc91f0231 241 chkSum[0]=0; chkSum[1]=0;
nixnax 12:db0dc91f0231 242 headerCheckSum(); // new ip header checksum
nixnax 12:db0dc91f0231 243 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 244 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 12:db0dc91f0231 245 icmpSum[0]=0; icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 246 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 16:cb0b80c24ba2 247 int sum = dataCheckSum( icmpType, icmpLength); // this checksum on icmp data portion
nixnax 12:db0dc91f0231 248 icmpSum[0]=sum>>8; icmpSum[1]=sum; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 249
nixnax 16:cb0b80c24ba2 250 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 13:d882b8a042b4 251 char * icmpData = icmpType+8; // the actual data is after the header
nixnax 15:b0154c910143 252 if (printSize > 10) printSize = 10; // print only first 20 characters
nixnax 16:cb0b80c24ba2 253 for (int i=0; i<printSize; i++) { char ch = icmpData[i]; if (ch>31 && ch<127) { debug(("%c",ch)); } else { debug(("%c",'_')); }}
nixnax 15:b0154c910143 254 debug(("%c",'\n'));
nixnax 15:b0154c910143 255
nixnax 15:b0154c910143 256 sendFrame(); // reply to the ping
nixnax 15:b0154c910143 257
nixnax 16:cb0b80c24ba2 258
nixnax 12:db0dc91f0231 259 } else {
nixnax 15:b0154c910143 260 debug(("ICMP type=%d \n", icmpType[0]));
nixnax 11:f58998c24f0b 261 }
nixnax 11:f58998c24f0b 262 }
nixnax 11:f58998c24f0b 263
nixnax 11:f58998c24f0b 264 void IGMPpacket() { // internet group management protocol
nixnax 15:b0154c910143 265 debug(("IGMP type=%d \n", ppp.pkt.buf[28]));
nixnax 11:f58998c24f0b 266 }
nixnax 11:f58998c24f0b 267
nixnax 11:f58998c24f0b 268 void TCPpacket() {
nixnax 15:b0154c910143 269 debug(("TCP\n"));
nixnax 10:74f8233f72c0 270 /*
nixnax 11:f58998c24f0b 271 switch (protocol) {
nixnax 11:f58998c24f0b 272 case 2: TCPsyn(); break;
nixnax 11:f58998c24f0b 273 case 17: TCPack(); break;
nixnax 11:f58998c24f0b 274 case 6: TCPpacket(); break;
nixnax 15:b0154c910143 275 default: debug(((( "Other \n");
nixnax 11:f58998c24f0b 276 }
nixnax 10:74f8233f72c0 277 */
nixnax 10:74f8233f72c0 278 }
nixnax 10:74f8233f72c0 279
nixnax 11:f58998c24f0b 280 void otherProtocol() {
nixnax 15:b0154c910143 281 debug(("Other IP protocol"));
nixnax 11:f58998c24f0b 282 }
nixnax 11:f58998c24f0b 283
nixnax 10:74f8233f72c0 284 void IPframe() {
nixnax 10:74f8233f72c0 285 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 286 switch (protocol) {
nixnax 11:f58998c24f0b 287 case 1: ICMPpacket(); break;
nixnax 11:f58998c24f0b 288 case 2: IGMPpacket(); break;
nixnax 11:f58998c24f0b 289 case 17: UDPpacket(); break;
nixnax 11:f58998c24f0b 290 case 6: TCPpacket(); break;
nixnax 11:f58998c24f0b 291 default: otherProtocol();
nixnax 10:74f8233f72c0 292 }
nixnax 15:b0154c910143 293 //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 294 }
nixnax 9:0992486d4a30 295
nixnax 9:0992486d4a30 296 void LCPconfReq() {
nixnax 15:b0154c910143 297 debug(("LCP Config "));
nixnax 9:0992486d4a30 298 if (ppp.pkt.buf[7] != 4) {
nixnax 11:f58998c24f0b 299 ppp.pkt.buf[4]=4; // allow only no options
nixnax 15:b0154c910143 300 debug(("Reject\n"));
nixnax 9:0992486d4a30 301 sendFrame();
nixnax 9:0992486d4a30 302 } else {
nixnax 9:0992486d4a30 303 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 15:b0154c910143 304 debug(("Ack\n"));
nixnax 9:0992486d4a30 305 sendFrame();
nixnax 15:b0154c910143 306 debug(("LCP Ask\n"));
nixnax 11:f58998c24f0b 307 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 308 sendFrame();
nixnax 9:0992486d4a30 309 }
nixnax 9:0992486d4a30 310 }
nixnax 9:0992486d4a30 311
nixnax 9:0992486d4a30 312 void LCPconfAck() {
nixnax 15:b0154c910143 313 debug(("LCP Ack\n"));
nixnax 9:0992486d4a30 314 }
nixnax 9:0992486d4a30 315
nixnax 9:0992486d4a30 316 void LCPend(){
nixnax 15:b0154c910143 317 debug(("LCP End\n"));
nixnax 12:db0dc91f0231 318 ppp.online=0; // start hunting for connect string again
nixnax 9:0992486d4a30 319 ppp.pkt.buf[4]=6;
nixnax 12:db0dc91f0231 320 sendFrame(); // acknowledge
nixnax 9:0992486d4a30 321 }
nixnax 9:0992486d4a30 322
nixnax 9:0992486d4a30 323 void LCPother(){
nixnax 15:b0154c910143 324 debug(("LCP Other\n"));
nixnax 12:db0dc91f0231 325 dumpFrame();
nixnax 9:0992486d4a30 326 }
nixnax 9:0992486d4a30 327
nixnax 9:0992486d4a30 328 void LCPframe(){
nixnax 9:0992486d4a30 329 int code = ppp.pkt.buf[4];
nixnax 9:0992486d4a30 330 switch (code) {
nixnax 12:db0dc91f0231 331 case 1: LCPconfReq(); break; // config request
nixnax 12:db0dc91f0231 332 case 2: LCPconfAck(); break; // config ack
nixnax 12:db0dc91f0231 333 case 5: LCPend(); break; // end connection
nixnax 12:db0dc91f0231 334 default: LCPother();
nixnax 9:0992486d4a30 335 }
nixnax 9:0992486d4a30 336 }
nixnax 9:0992486d4a30 337
nixnax 12:db0dc91f0231 338 void discardedFrame() {
nixnax 15:b0154c910143 339 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 340 }
nixnax 9:0992486d4a30 341
nixnax 9:0992486d4a30 342 void determinePacketType() {
nixnax 15:b0154c910143 343 if ( ppp.pkt.buf[0] != 0xff ) { debug(("byte0 != ff\n")); return;}
nixnax 15:b0154c910143 344 if ( ppp.pkt.buf[1] != 3 ) { debug(("byte1 != 3\n")); return;}
nixnax 15:b0154c910143 345 if ( ppp.pkt.buf[3] != 0x21 ) { debug(("byte2 != 21\n")); return;}
nixnax 9:0992486d4a30 346 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 347 switch (packetType) {
nixnax 12:db0dc91f0231 348 case 0xc0: LCPframe(); break; // link control
nixnax 12:db0dc91f0231 349 case 0x80: IPCPframe(); break; // IP control
nixnax 12:db0dc91f0231 350 case 0x00: IPframe(); break; // IP itself
nixnax 12:db0dc91f0231 351 default: discardedFrame();
nixnax 9:0992486d4a30 352 }
nixnax 9:0992486d4a30 353 }
nixnax 9:0992486d4a30 354
nixnax 9:0992486d4a30 355 void scanForConnectString() {
nixnax 9:0992486d4a30 356 if ( ppp.online==0 ) {
nixnax 15:b0154c910143 357 char * clientFound = strstr( (char *)rxbuf, "CLIENTCLIENT" ); // look for PC string
nixnax 9:0992486d4a30 358 if( clientFound ) {
nixnax 9:0992486d4a30 359 strcpy( clientFound, "FOUND!FOUND!" ); // overwrite so we don't get fixated
nixnax 9:0992486d4a30 360 pc.printf("CLIENTSERVER"); // respond to PC
nixnax 9:0992486d4a30 361 ppp.online=1; // we can stop looking for the string
nixnax 15:b0154c910143 362 debug(("Connect string found\n"));
nixnax 9:0992486d4a30 363 }
nixnax 9:0992486d4a30 364 }
nixnax 9:0992486d4a30 365 }
nixnax 9:0992486d4a30 366
nixnax 0:2cf4880c312a 367 int main()
nixnax 0:2cf4880c312a 368 {
nixnax 14:c65831c25aaa 369 pc.baud(115200); // USB virtual serial port
nixnax 15:b0154c910143 370 xx.baud(115200); // second serial port for debug(((((((( messages
nixnax 9:0992486d4a30 371 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 4:a469050d5b80 372
nixnax 9:0992486d4a30 373 pppInitStruct(); // initialize all the PPP properties
nixnax 4:a469050d5b80 374
nixnax 9:0992486d4a30 375 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 4:a469050d5b80 376
nixnax 9:0992486d4a30 377 int frameStartIndex, frameEndIndex; int frameBusy=0;
nixnax 4:a469050d5b80 378
nixnax 0:2cf4880c312a 379 while(1) {
nixnax 9:0992486d4a30 380 if ( ppp.online==0 ) scanForConnectString(); // try to connect
nixnax 0:2cf4880c312a 381 while ( pc_readable() ) {
nixnax 1:9e03798d4367 382 int rx = pc_getBuf();
nixnax 4:a469050d5b80 383 if (frameBusy) {
nixnax 4:a469050d5b80 384 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 385 frameBusy=0; // done gathering frame
nixnax 4:a469050d5b80 386 frameEndIndex=ppp.rx.tail-1; // remember where frame ends
nixnax 4:a469050d5b80 387 processFrame(frameStartIndex, frameEndIndex);
nixnax 4:a469050d5b80 388 }
nixnax 4:a469050d5b80 389 }
nixnax 4:a469050d5b80 390 else {
nixnax 4:a469050d5b80 391 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 392 frameBusy=1; // start gathering frame
nixnax 9:0992486d4a30 393 frameStartIndex=ppp.rx.tail; // remember where frame started
nixnax 4:a469050d5b80 394 }
nixnax 0:2cf4880c312a 395 }
nixnax 4:a469050d5b80 396 }
nixnax 7:ab147f5e97ac 397 }
nixnax 7:ab147f5e97ac 398 }