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@11:f58998c24f0b, 2016-12-31 (annotated)

Committer:
nixnax
Date:
Sat Dec 31 14:35:27 2016 +0000
Revision:
11:f58998c24f0b
Parent:
10:74f8233f72c0
Child:
12:db0dc91f0231
UDP and ICMP-ping working!

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nixnax 0:2cf4880c312a 1 #include "mbed.h"
nixnax 0:2cf4880c312a 2
nixnax 0:2cf4880c312a 3 // Proof-of-concept for TCP/IP using Windows 7/8/10 Dial Up Networking over MBED USB Virtual COM Port
nixnax 0:2cf4880c312a 4
nixnax 4:a469050d5b80 5 // Toggles LED1 every time the PC sends an IP packet over the PPP link
nixnax 4:a469050d5b80 6
nixnax 4:a469050d5b80 7 // Note - turn off all authentication, passwords, compression etc. Simplest link possible.
nixnax 0:2cf4880c312a 8
nixnax 9:0992486d4a30 9 // Handy links
nixnax 6:fba4c2e817b8 10 // http://atari.kensclassics.org/wcomlog.htm
nixnax 6:fba4c2e817b8 11 // https://technet.microsoft.com/en-us/library/cc957992.aspx
nixnax 6:fba4c2e817b8 12 // http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
nixnax 9:0992486d4a30 13 // https://en.wikibooks.org/wiki/Serial_Programming/IP_Over_Serial_Connections
nixnax 6:fba4c2e817b8 14
nixnax 6:fba4c2e817b8 15 Serial pc(USBTX, USBRX); // The USB com port - Set this up as a Dial-Up Modem on your pc
nixnax 4:a469050d5b80 16 Serial xx(PC_10, PC_11); // debug port - use a second USB serial port to monitor
nixnax 0:2cf4880c312a 17
nixnax 9:0992486d4a30 18 #define debug(x) xx.printf( x )
nixnax 9:0992486d4a30 19
nixnax 4:a469050d5b80 20 DigitalOut led1(LED1);
nixnax 4:a469050d5b80 21
nixnax 4:a469050d5b80 22 #define FRAME_7E (0x7e)
nixnax 9:0992486d4a30 23 #define BUFLEN (1<<12)
nixnax 4:a469050d5b80 24 char rxbuf[BUFLEN];
nixnax 4:a469050d5b80 25 char frbuf[3000]; // buffer for ppp frame
nixnax 0:2cf4880c312a 26
nixnax 4:a469050d5b80 27 struct {
nixnax 4:a469050d5b80 28 int online;
nixnax 4:a469050d5b80 29 struct {
nixnax 4:a469050d5b80 30 char * buf;
nixnax 4:a469050d5b80 31 int head;
nixnax 4:a469050d5b80 32 int tail;
nixnax 9:0992486d4a30 33 int total;
nixnax 4:a469050d5b80 34 } rx; // serial port buffer
nixnax 4:a469050d5b80 35 struct {
nixnax 6:fba4c2e817b8 36 int id;
nixnax 4:a469050d5b80 37 int len;
nixnax 4:a469050d5b80 38 int crc;
nixnax 4:a469050d5b80 39 char * buf;
nixnax 4:a469050d5b80 40 } pkt; // ppp buffer
nixnax 4:a469050d5b80 41 } ppp;
nixnax 0:2cf4880c312a 42
nixnax 9:0992486d4a30 43 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 44
nixnax 4:a469050d5b80 45 int crcG; // frame check sequence (CRC) holder
nixnax 4:a469050d5b80 46 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 47 void crcReset(){crcG=0xffff;} // crc restart
nixnax 9:0992486d4a30 48 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 49
nixnax 0:2cf4880c312a 50 void rxHandler() // serial port receive interrupt handler
nixnax 0:2cf4880c312a 51 {
nixnax 4:a469050d5b80 52 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in buffer
nixnax 0:2cf4880c312a 53 __disable_irq();
nixnax 4:a469050d5b80 54 ppp.rx.head=(ppp.rx.head+1)&(BUFLEN-1);
nixnax 9:0992486d4a30 55 ppp.rx.total++;
nixnax 0:2cf4880c312a 56 __enable_irq();
nixnax 0:2cf4880c312a 57 }
nixnax 0:2cf4880c312a 58
nixnax 0:2cf4880c312a 59 int pc_readable() // check if buffer has data
nixnax 0:2cf4880c312a 60 {
nixnax 4:a469050d5b80 61 return (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 0:2cf4880c312a 62 }
nixnax 0:2cf4880c312a 63
nixnax 0:2cf4880c312a 64 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 65 {
nixnax 0:2cf4880c312a 66 if (pc_readable()) {
nixnax 4:a469050d5b80 67 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 4:a469050d5b80 68 ppp.rx.tail=(ppp.rx.tail+1)&(BUFLEN-1);
nixnax 0:2cf4880c312a 69 return x;
nixnax 0:2cf4880c312a 70 }
nixnax 0:2cf4880c312a 71 return -1;
nixnax 0:2cf4880c312a 72 }
nixnax 0:2cf4880c312a 73
nixnax 4:a469050d5b80 74 void scanForConnectString(); // scan for connect attempts from pc
nixnax 1:9e03798d4367 75
nixnax 9:0992486d4a30 76 void processFrame(int start, int end) { // process received frame
nixnax 9:0992486d4a30 77 if(start==end) { xx.printf("Null Frame c=%d\n",ppp.rx.total); pc.putc(0x7e); return; }
nixnax 9:0992486d4a30 78 crcReset();
nixnax 9:0992486d4a30 79 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 80 ppp.pkt.len=0;
nixnax 9:0992486d4a30 81 int unstuff=0;
nixnax 9:0992486d4a30 82 for (int i=start; i<end; i++) {
nixnax 9:0992486d4a30 83 if (unstuff==0) {
nixnax 9:0992486d4a30 84 if (rxbuf[i]==0x7d) unstuff=1;
nixnax 9:0992486d4a30 85 else { *dest++ = rxbuf[i]; ppp.pkt.len++; crcDo(rxbuf[i]);}
nixnax 9:0992486d4a30 86 } else {
nixnax 9:0992486d4a30 87 *dest++ = rxbuf[i]^0x20; ppp.pkt.len++; crcDo((int)rxbuf[i]^0x20);
nixnax 9:0992486d4a30 88 unstuff=0;
nixnax 9:0992486d4a30 89 }
nixnax 9:0992486d4a30 90 }
nixnax 9:0992486d4a30 91 ppp.pkt.crc = crcG & 0xffff;
nixnax 9:0992486d4a30 92 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 9:0992486d4a30 93 void determinePacketType(); // declare early
nixnax 9:0992486d4a30 94 determinePacketType();
nixnax 9:0992486d4a30 95 } else {
nixnax 9:0992486d4a30 96 xx.printf("CRC was %x \n",ppp.pkt.crc);
nixnax 9:0992486d4a30 97 for(int i=0;i<ppp.pkt.len;i++)xx.printf("%02x ", ppp.pkt.buf[i]);
nixnax 9:0992486d4a30 98 xx.printf("\nLen = %d\n", ppp.pkt.len);
nixnax 9:0992486d4a30 99 }
nixnax 9:0992486d4a30 100 }
nixnax 9:0992486d4a30 101
nixnax 11:f58998c24f0b 102 void dumpFrame() {
nixnax 11:f58998c24f0b 103 for(int i=0;i<ppp.pkt.len/2;i++) xx.printf("%02x ", ppp.pkt.buf[i]);
nixnax 11:f58998c24f0b 104 xx.printf(" C %02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len);
nixnax 11:f58998c24f0b 105 }
nixnax 9:0992486d4a30 106
nixnax 9:0992486d4a30 107 void generalFrame() {
nixnax 9:0992486d4a30 108 debug("== General Frame ==\n");
nixnax 11:f58998c24f0b 109 dumpFrame();
nixnax 9:0992486d4a30 110 }
nixnax 9:0992486d4a30 111
nixnax 9:0992486d4a30 112 void sendFrame(){
nixnax 9:0992486d4a30 113 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // get crc
nixnax 9:0992486d4a30 114 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo
nixnax 9:0992486d4a30 115 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi
nixnax 9:0992486d4a30 116 pc.putc(0x7e); // frame flag
nixnax 9:0992486d4a30 117 for(int i=0;i<ppp.pkt.len;i++) {
nixnax 11:f58998c24f0b 118 //xx.printf( "%2x ", ppp.pkt.buf[i]);
nixnax 9:0992486d4a30 119 unsigned int cc = (unsigned int)ppp.pkt.buf[i];
nixnax 9:0992486d4a30 120 if (cc>32) pc.putc(cc); else {pc.putc(0x7d); pc.putc(cc+32);}
nixnax 9:0992486d4a30 121 }
nixnax 9:0992486d4a30 122 pc.putc(0x7e); // frame flag
nixnax 9:0992486d4a30 123 }
nixnax 9:0992486d4a30 124
nixnax 9:0992486d4a30 125 void ipRequestHandler(){
nixnax 9:0992486d4a30 126 debug("IPCP Conf ");
nixnax 9:0992486d4a30 127 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 9:0992486d4a30 128 debug("Rej\n"); // reject if any options are requested
nixnax 9:0992486d4a30 129 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 130 sendFrame();
nixnax 9:0992486d4a30 131 } else {
nixnax 9:0992486d4a30 132 debug("Ack\n");
nixnax 9:0992486d4a30 133 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 134 sendFrame(); // acknowledge
nixnax 9:0992486d4a30 135 // send our own request now
nixnax 9:0992486d4a30 136 debug("IPCP Ask\n");
nixnax 9:0992486d4a30 137 ppp.pkt.buf[4]=1; // request the minimum
nixnax 9:0992486d4a30 138 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 139 sendFrame(); // this is our request
nixnax 9:0992486d4a30 140 }
nixnax 9:0992486d4a30 141 }
nixnax 9:0992486d4a30 142
nixnax 9:0992486d4a30 143 void ipAckHandler(){ debug("IPCP Grant\n"); }
nixnax 9:0992486d4a30 144
nixnax 9:0992486d4a30 145 void ipNackHandler(){ debug("IPCP Nack\n"); }
nixnax 9:0992486d4a30 146
nixnax 9:0992486d4a30 147 void ipDefaultHandler(){ debug("IPCP Other\n"); }
nixnax 9:0992486d4a30 148
nixnax 9:0992486d4a30 149 void IPCPframe() {
nixnax 9:0992486d4a30 150 led1 = ppp.pkt.buf[5] & 1; // This is the sequence number so the led blinks on packets
nixnax 9:0992486d4a30 151 //ppp.pkt.id = ppp.pkt.buf[5]; // remember the sequence number
nixnax 9:0992486d4a30 152 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 153 switch (code) {
nixnax 9:0992486d4a30 154 case 1: ipRequestHandler(); break;
nixnax 9:0992486d4a30 155 case 2: ipAckHandler(); break;
nixnax 9:0992486d4a30 156 case 3: ipNackHandler(); break;
nixnax 9:0992486d4a30 157 default: ipDefaultHandler();
nixnax 9:0992486d4a30 158 }
nixnax 9:0992486d4a30 159 }
nixnax 9:0992486d4a30 160
nixnax 10:74f8233f72c0 161 void UDPpacket() {
nixnax 10:74f8233f72c0 162 int idx = 4+((ppp.pkt.buf[4]&0xf)*4);
nixnax 10:74f8233f72c0 163 int srcPort = (ppp.pkt.buf[idx+0]<<8)|ppp.pkt.buf[idx+1];
nixnax 11:f58998c24f0b 164 int dstPort = (ppp.pkt.buf[idx+2]<<8)|ppp.pkt.buf[idx+3];
nixnax 11:f58998c24f0b 165 xx.printf("UDP %d.%d.%d.%d:%d ", ppp.pkt.buf[16],ppp.pkt.buf[17],ppp.pkt.buf[18],ppp.pkt.buf[19],srcPort);
nixnax 11:f58998c24f0b 166 xx.printf("%d.%d.%d.%d:%d\n", ppp.pkt.buf[20],ppp.pkt.buf[21],ppp.pkt.buf[22],ppp.pkt.buf[23],dstPort);
nixnax 11:f58998c24f0b 167 }
nixnax 11:f58998c24f0b 168
nixnax 11:f58998c24f0b 169
nixnax 11:f58998c24f0b 170 int dataCheckSum(char * ptr, int len) {
nixnax 11:f58998c24f0b 171 int sum=0;
nixnax 11:f58998c24f0b 172
nixnax 11:f58998c24f0b 173 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 174 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 175 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 176 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 177 sum = sum + val;
nixnax 11:f58998c24f0b 178 }
nixnax 11:f58998c24f0b 179 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 180 sum = ~sum;
nixnax 11:f58998c24f0b 181 return sum;
nixnax 11:f58998c24f0b 182 }
nixnax 11:f58998c24f0b 183
nixnax 11:f58998c24f0b 184
nixnax 11:f58998c24f0b 185 void headerCheckSum() {
nixnax 11:f58998c24f0b 186 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 187 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 188 int sum=0;
nixnax 11:f58998c24f0b 189
nixnax 11:f58998c24f0b 190 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 191 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 192 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 193 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 194 sum = sum + val;
nixnax 11:f58998c24f0b 195 }
nixnax 11:f58998c24f0b 196 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 197 sum = ~sum;
nixnax 11:f58998c24f0b 198 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 199 ppp.pkt.buf[15]= (sum );
nixnax 11:f58998c24f0b 200
nixnax 11:f58998c24f0b 201
nixnax 11:f58998c24f0b 202
nixnax 9:0992486d4a30 203 }
nixnax 9:0992486d4a30 204
nixnax 11:f58998c24f0b 205 void ICMPpacket() { // internet control message protocol
nixnax 11:f58998c24f0b 206
nixnax 11:f58998c24f0b 207 int headerSize = ((ppp.pkt.buf[4]&0xf)*4);
nixnax 11:f58998c24f0b 208 int idx = headerSize + 4;
nixnax 11:f58998c24f0b 209 xx.printf("ICMP type=%d \n", ppp.pkt.buf[idx]);
nixnax 11:f58998c24f0b 210 if ( ppp.pkt.buf[idx] == 8 ) {
nixnax 11:f58998c24f0b 211 ppp.pkt.buf[12] = ppp.pkt.buf[12]-1; // TTL decrement
nixnax 11:f58998c24f0b 212 char src[4]; char dst[4];
nixnax 11:f58998c24f0b 213 memcpy(src, ppp.pkt.buf+16,4);
nixnax 11:f58998c24f0b 214 memcpy(dst, ppp.pkt.buf+20,4);
nixnax 11:f58998c24f0b 215 memcpy(ppp.pkt.buf+16,dst,4);
nixnax 11:f58998c24f0b 216 memcpy(ppp.pkt.buf+20,src,4); // swap src & dest ip
nixnax 11:f58998c24f0b 217 ppp.pkt.buf[15]=0;
nixnax 11:f58998c24f0b 218 ppp.pkt.buf[14]=0;
nixnax 11:f58998c24f0b 219 headerCheckSum(); // calc ip header checksum
nixnax 11:f58998c24f0b 220
nixnax 11:f58998c24f0b 221
nixnax 11:f58998c24f0b 222 int packetLength = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7];
nixnax 11:f58998c24f0b 223 int dataLength = packetLength - headerSize;
nixnax 11:f58998c24f0b 224 ppp.pkt.buf[idx]=0; ppp.pkt.buf[idx+2]=0; ppp.pkt.buf[idx+3]=0;
nixnax 11:f58998c24f0b 225 int sum = dataCheckSum( ppp.pkt.buf+idx, dataLength); // calc icmp data checksum
nixnax 11:f58998c24f0b 226 ppp.pkt.buf[idx+2]=(sum>>8); ppp.pkt.buf[idx+3]=(sum );
nixnax 11:f58998c24f0b 227 sendFrame();
nixnax 11:f58998c24f0b 228 }
nixnax 11:f58998c24f0b 229 }
nixnax 11:f58998c24f0b 230
nixnax 11:f58998c24f0b 231 void IGMPpacket() { // internet group management protocol
nixnax 11:f58998c24f0b 232 xx.printf("IGMP type=%d \n", ppp.pkt.buf[28]);
nixnax 11:f58998c24f0b 233 }
nixnax 11:f58998c24f0b 234
nixnax 11:f58998c24f0b 235 void TCPpacket() {
nixnax 11:f58998c24f0b 236 debug("TCP\n");
nixnax 10:74f8233f72c0 237 /*
nixnax 11:f58998c24f0b 238 switch (protocol) {
nixnax 11:f58998c24f0b 239 case 2: TCPsyn(); break;
nixnax 11:f58998c24f0b 240 case 17: TCPack(); break;
nixnax 11:f58998c24f0b 241 case 6: TCPpacket(); break;
nixnax 11:f58998c24f0b 242 default: debug( "Other \n");
nixnax 11:f58998c24f0b 243 }
nixnax 10:74f8233f72c0 244 */
nixnax 10:74f8233f72c0 245 }
nixnax 10:74f8233f72c0 246
nixnax 11:f58998c24f0b 247 void otherProtocol() {
nixnax 11:f58998c24f0b 248 debug("Other protocol");
nixnax 11:f58998c24f0b 249 }
nixnax 11:f58998c24f0b 250
nixnax 10:74f8233f72c0 251 void IPframe() {
nixnax 10:74f8233f72c0 252 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 253 switch (protocol) {
nixnax 11:f58998c24f0b 254 case 1: ICMPpacket(); break;
nixnax 11:f58998c24f0b 255 case 2: IGMPpacket(); break;
nixnax 11:f58998c24f0b 256 case 17: UDPpacket(); break;
nixnax 11:f58998c24f0b 257 case 6: TCPpacket(); break;
nixnax 11:f58998c24f0b 258 default: otherProtocol();
nixnax 10:74f8233f72c0 259 }
nixnax 10:74f8233f72c0 260 //xx.printf("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 261 }
nixnax 9:0992486d4a30 262
nixnax 9:0992486d4a30 263
nixnax 9:0992486d4a30 264 void LCPconfReq() {
nixnax 11:f58998c24f0b 265 debug("LCP Config ");
nixnax 9:0992486d4a30 266 if (ppp.pkt.buf[7] != 4) {
nixnax 11:f58998c24f0b 267 ppp.pkt.buf[4]=4; // allow only no options
nixnax 11:f58998c24f0b 268 debug("Reject\n");
nixnax 9:0992486d4a30 269 sendFrame();
nixnax 9:0992486d4a30 270 } else {
nixnax 9:0992486d4a30 271 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 9:0992486d4a30 272 debug("Ack\n");
nixnax 9:0992486d4a30 273 sendFrame();
nixnax 10:74f8233f72c0 274 debug("LCP Ask\n");
nixnax 11:f58998c24f0b 275 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 276 sendFrame();
nixnax 9:0992486d4a30 277 }
nixnax 9:0992486d4a30 278 }
nixnax 9:0992486d4a30 279
nixnax 9:0992486d4a30 280 void LCPconfAck() {
nixnax 9:0992486d4a30 281 debug("LCP Ack\n");
nixnax 9:0992486d4a30 282 }
nixnax 9:0992486d4a30 283
nixnax 9:0992486d4a30 284 void LCPend(){
nixnax 9:0992486d4a30 285 debug("LCP End\n");
nixnax 9:0992486d4a30 286 ppp.online=0;
nixnax 9:0992486d4a30 287 ppp.pkt.buf[4]=6;
nixnax 9:0992486d4a30 288 sendFrame();
nixnax 9:0992486d4a30 289 }
nixnax 9:0992486d4a30 290
nixnax 9:0992486d4a30 291 void LCPother(){
nixnax 9:0992486d4a30 292 debug("LCP Other\n");
nixnax 9:0992486d4a30 293 generalFrame();
nixnax 9:0992486d4a30 294 }
nixnax 9:0992486d4a30 295
nixnax 9:0992486d4a30 296 void LCPframe(){
nixnax 9:0992486d4a30 297 int code = ppp.pkt.buf[4];
nixnax 9:0992486d4a30 298 switch (code) {
nixnax 9:0992486d4a30 299 case 1: LCPconfReq(); break;
nixnax 9:0992486d4a30 300 case 2: LCPconfAck(); break;
nixnax 9:0992486d4a30 301 case 5: LCPend(); break;
nixnax 9:0992486d4a30 302 default: LCPother();
nixnax 9:0992486d4a30 303 }
nixnax 9:0992486d4a30 304 }
nixnax 9:0992486d4a30 305
nixnax 9:0992486d4a30 306 void xx21frame() {
nixnax 9:0992486d4a30 307 debug("Unknown frame type ff 03 xx 21\n");
nixnax 9:0992486d4a30 308 }
nixnax 9:0992486d4a30 309
nixnax 9:0992486d4a30 310 void determinePacketType() {
nixnax 9:0992486d4a30 311 if ( ppp.pkt.buf[0] != 0xff ) {debug("byte0 != ff\n"); return;}
nixnax 9:0992486d4a30 312 if ( ppp.pkt.buf[1] != 3 ) {debug("byte1 != 3\n"); return;}
nixnax 9:0992486d4a30 313 if ( ppp.pkt.buf[3] != 0x21 ) {debug("byte2 != 21\n"); return;}
nixnax 9:0992486d4a30 314 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 315 switch (packetType) {
nixnax 9:0992486d4a30 316 case 0xc0: LCPframe(); break;
nixnax 9:0992486d4a30 317 case 0x80: IPCPframe(); break;
nixnax 9:0992486d4a30 318 case 0x00: IPframe(); break;
nixnax 9:0992486d4a30 319 default: xx21frame(); break;
nixnax 9:0992486d4a30 320 }
nixnax 9:0992486d4a30 321 }
nixnax 9:0992486d4a30 322
nixnax 9:0992486d4a30 323 void scanForConnectString() {
nixnax 9:0992486d4a30 324 if ( ppp.online==0 ) {
nixnax 9:0992486d4a30 325 char * clientFound = strstr( rxbuf, "CLIENTCLIENT" ); // look for PC string
nixnax 9:0992486d4a30 326 if( clientFound ) {
nixnax 9:0992486d4a30 327 strcpy( clientFound, "FOUND!FOUND!" ); // overwrite so we don't get fixated
nixnax 9:0992486d4a30 328 pc.printf("CLIENTSERVER"); // respond to PC
nixnax 9:0992486d4a30 329 ppp.online=1; // we can stop looking for the string
nixnax 9:0992486d4a30 330 debug("Connect string found\n");
nixnax 9:0992486d4a30 331 }
nixnax 9:0992486d4a30 332 }
nixnax 9:0992486d4a30 333 }
nixnax 9:0992486d4a30 334
nixnax 0:2cf4880c312a 335 int main()
nixnax 0:2cf4880c312a 336 {
nixnax 9:0992486d4a30 337 pc.baud(9600);
nixnax 4:a469050d5b80 338 xx.baud(115200);
nixnax 9:0992486d4a30 339 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 4:a469050d5b80 340
nixnax 9:0992486d4a30 341 pppInitStruct(); // initialize all the PPP properties
nixnax 4:a469050d5b80 342
nixnax 9:0992486d4a30 343 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 4:a469050d5b80 344
nixnax 9:0992486d4a30 345 int frameStartIndex, frameEndIndex; int frameBusy=0;
nixnax 4:a469050d5b80 346
nixnax 0:2cf4880c312a 347 while(1) {
nixnax 9:0992486d4a30 348 if ( ppp.online==0 ) scanForConnectString(); // try to connect
nixnax 0:2cf4880c312a 349 while ( pc_readable() ) {
nixnax 1:9e03798d4367 350 int rx = pc_getBuf();
nixnax 9:0992486d4a30 351 wait(0.001);
nixnax 4:a469050d5b80 352 if (frameBusy) {
nixnax 4:a469050d5b80 353 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 354 frameBusy=0; // done gathering frame
nixnax 4:a469050d5b80 355 frameEndIndex=ppp.rx.tail-1; // remember where frame ends
nixnax 4:a469050d5b80 356 void processFrame(int start, int end); // process a received frame
nixnax 4:a469050d5b80 357 processFrame(frameStartIndex, frameEndIndex);
nixnax 4:a469050d5b80 358 }
nixnax 4:a469050d5b80 359 }
nixnax 4:a469050d5b80 360 else {
nixnax 4:a469050d5b80 361 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 362 frameBusy=1; // start gathering frame
nixnax 9:0992486d4a30 363 frameStartIndex=ppp.rx.tail; // remember where frame started
nixnax 4:a469050d5b80 364 }
nixnax 0:2cf4880c312a 365 }
nixnax 4:a469050d5b80 366 }
nixnax 7:ab147f5e97ac 367 }
nixnax 7:ab147f5e97ac 368 }