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@10:74f8233f72c0, 2016-12-31 (annotated)

Committer:
nixnax
Date:
Sat Dec 31 03:13:46 2016 +0000
Revision:
10:74f8233f72c0
Parent:
9:0992486d4a30
Child:
11:f58998c24f0b
Can receive UDP packets.

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 9:0992486d4a30 102
nixnax 9:0992486d4a30 103 void generalFrame() {
nixnax 9:0992486d4a30 104 debug("== General Frame ==\n");
nixnax 9:0992486d4a30 105 for(int i=0;i<ppp.pkt.len;i++) xx.printf("%02x ", ppp.pkt.buf[i]);
nixnax 9:0992486d4a30 106 xx.printf(" C %02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len);
nixnax 9:0992486d4a30 107 }
nixnax 9:0992486d4a30 108
nixnax 9:0992486d4a30 109 void sendFrame(){
nixnax 9:0992486d4a30 110 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // get crc
nixnax 9:0992486d4a30 111 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo
nixnax 9:0992486d4a30 112 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi
nixnax 9:0992486d4a30 113 pc.putc(0x7e); // frame flag
nixnax 9:0992486d4a30 114 for(int i=0;i<ppp.pkt.len;i++) {
nixnax 9:0992486d4a30 115 unsigned int cc = (unsigned int)ppp.pkt.buf[i];
nixnax 9:0992486d4a30 116 if (cc>32) pc.putc(cc); else {pc.putc(0x7d); pc.putc(cc+32);}
nixnax 9:0992486d4a30 117 }
nixnax 9:0992486d4a30 118 pc.putc(0x7e); // frame flag
nixnax 9:0992486d4a30 119 }
nixnax 9:0992486d4a30 120
nixnax 9:0992486d4a30 121 void ipRequestHandler(){
nixnax 9:0992486d4a30 122 debug("IPCP Conf ");
nixnax 9:0992486d4a30 123 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 9:0992486d4a30 124 debug("Rej\n"); // reject if any options are requested
nixnax 9:0992486d4a30 125 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 126 sendFrame();
nixnax 9:0992486d4a30 127 } else {
nixnax 9:0992486d4a30 128 debug("Ack\n");
nixnax 9:0992486d4a30 129 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 130 sendFrame(); // acknowledge
nixnax 9:0992486d4a30 131 // send our own request now
nixnax 9:0992486d4a30 132 debug("IPCP Ask\n");
nixnax 9:0992486d4a30 133 ppp.pkt.buf[4]=1; // request the minimum
nixnax 9:0992486d4a30 134 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 135 sendFrame(); // this is our request
nixnax 9:0992486d4a30 136 }
nixnax 9:0992486d4a30 137 }
nixnax 9:0992486d4a30 138
nixnax 9:0992486d4a30 139 void ipAckHandler(){ debug("IPCP Grant\n"); }
nixnax 9:0992486d4a30 140
nixnax 9:0992486d4a30 141 void ipNackHandler(){ debug("IPCP Nack\n"); }
nixnax 9:0992486d4a30 142
nixnax 9:0992486d4a30 143 void ipDefaultHandler(){ debug("IPCP Other\n"); }
nixnax 9:0992486d4a30 144
nixnax 9:0992486d4a30 145 void IPCPframe() {
nixnax 9:0992486d4a30 146 led1 = ppp.pkt.buf[5] & 1; // This is the sequence number so the led blinks on packets
nixnax 9:0992486d4a30 147 //ppp.pkt.id = ppp.pkt.buf[5]; // remember the sequence number
nixnax 9:0992486d4a30 148 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 149 switch (code) {
nixnax 9:0992486d4a30 150 case 1: ipRequestHandler(); break;
nixnax 9:0992486d4a30 151 case 2: ipAckHandler(); break;
nixnax 9:0992486d4a30 152 case 3: ipNackHandler(); break;
nixnax 9:0992486d4a30 153 default: ipDefaultHandler();
nixnax 9:0992486d4a30 154 }
nixnax 9:0992486d4a30 155 }
nixnax 9:0992486d4a30 156
nixnax 10:74f8233f72c0 157 void UDPpacket() {
nixnax 10:74f8233f72c0 158 xx.printf("UDP %d.%d.%d.%d %d.%d.%d.%d\n", 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 159 int idx = 4+((ppp.pkt.buf[4]&0xf)*4);
nixnax 10:74f8233f72c0 160 int srcPort = (ppp.pkt.buf[idx+0]<<8)|ppp.pkt.buf[idx+1];
nixnax 10:74f8233f72c0 161 int destPort = (ppp.pkt.buf[idx+2]<<8)|ppp.pkt.buf[idx+3];
nixnax 10:74f8233f72c0 162 xx.printf("Src %04x Dest %04x\n", srcPort, destPort);
nixnax 9:0992486d4a30 163 }
nixnax 9:0992486d4a30 164
nixnax 10:74f8233f72c0 165 void ICMPpacket() {
nixnax 10:74f8233f72c0 166 xx.printf("ICMP\n");
nixnax 10:74f8233f72c0 167 /*
nixnax 10:74f8233f72c0 168 xx.printf("ICMP len %4d %d.%d.%d.%d %d.%d.%d.%d\n", (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 169 xx.printf("Byte0 = %02x\n", ppp.pkt.buf[4]);
nixnax 10:74f8233f72c0 170 xx.printf("Type %x Code %d\n", ppp.pkt.buf[28], ppp.pkt.buf[29]);
nixnax 10:74f8233f72c0 171 xx.printf("Number of records %d %d\n", ppp.pkt.buf[34],ppp.pkt.buf[35]);
nixnax 10:74f8233f72c0 172 xx.printf("Group %d.%d.%d.%d\n", ppp.pkt.buf[36],ppp.pkt.buf[37],ppp.pkt.buf[38],ppp.pkt.buf[39]);
nixnax 10:74f8233f72c0 173 */
nixnax 10:74f8233f72c0 174
nixnax 10:74f8233f72c0 175 }
nixnax 10:74f8233f72c0 176
nixnax 10:74f8233f72c0 177 void IPframe() {
nixnax 10:74f8233f72c0 178 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 179 switch (protocol) {
nixnax 10:74f8233f72c0 180 case 2: ICMPpacket(); break;
nixnax 10:74f8233f72c0 181 case 17: UDPpacket(); break;
nixnax 10:74f8233f72c0 182 case 6: debug( "TCP \n" ); break;
nixnax 10:74f8233f72c0 183 default: debug( "Other \n");
nixnax 10:74f8233f72c0 184 }
nixnax 10:74f8233f72c0 185 //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 186 }
nixnax 9:0992486d4a30 187
nixnax 9:0992486d4a30 188
nixnax 9:0992486d4a30 189 void LCPconfReq() {
nixnax 9:0992486d4a30 190 debug("LCP Conf ");
nixnax 9:0992486d4a30 191 if (ppp.pkt.buf[7] != 4) {
nixnax 9:0992486d4a30 192 ppp.pkt.buf[4]=4; // allow only minimal requests
nixnax 9:0992486d4a30 193 debug("Rej\n");
nixnax 9:0992486d4a30 194 sendFrame();
nixnax 9:0992486d4a30 195 } else {
nixnax 9:0992486d4a30 196 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 9:0992486d4a30 197 debug("Ack\n");
nixnax 9:0992486d4a30 198 sendFrame();
nixnax 10:74f8233f72c0 199 debug("LCP Ask\n");
nixnax 9:0992486d4a30 200 ppp.pkt.buf[4]=1; // request zero conf
nixnax 9:0992486d4a30 201 sendFrame();
nixnax 9:0992486d4a30 202 }
nixnax 9:0992486d4a30 203 }
nixnax 9:0992486d4a30 204
nixnax 9:0992486d4a30 205 void LCPconfAck() {
nixnax 9:0992486d4a30 206 debug("LCP Ack\n");
nixnax 9:0992486d4a30 207 }
nixnax 9:0992486d4a30 208
nixnax 9:0992486d4a30 209 void LCPend(){
nixnax 9:0992486d4a30 210 debug("LCP End\n");
nixnax 9:0992486d4a30 211 ppp.online=0;
nixnax 9:0992486d4a30 212 ppp.pkt.buf[4]=6;
nixnax 9:0992486d4a30 213 sendFrame();
nixnax 9:0992486d4a30 214 }
nixnax 9:0992486d4a30 215
nixnax 9:0992486d4a30 216 void LCPother(){
nixnax 9:0992486d4a30 217 debug("LCP Other\n");
nixnax 9:0992486d4a30 218 generalFrame();
nixnax 9:0992486d4a30 219 }
nixnax 9:0992486d4a30 220
nixnax 9:0992486d4a30 221 void LCPframe(){
nixnax 9:0992486d4a30 222 int code = ppp.pkt.buf[4];
nixnax 9:0992486d4a30 223 switch (code) {
nixnax 9:0992486d4a30 224 case 1: LCPconfReq(); break;
nixnax 9:0992486d4a30 225 case 2: LCPconfAck(); break;
nixnax 9:0992486d4a30 226 case 5: LCPend(); break;
nixnax 9:0992486d4a30 227 default: LCPother();
nixnax 9:0992486d4a30 228 }
nixnax 9:0992486d4a30 229 }
nixnax 9:0992486d4a30 230
nixnax 9:0992486d4a30 231 void xx21frame() {
nixnax 9:0992486d4a30 232 debug("Unknown frame type ff 03 xx 21\n");
nixnax 9:0992486d4a30 233 }
nixnax 9:0992486d4a30 234
nixnax 9:0992486d4a30 235 void determinePacketType() {
nixnax 9:0992486d4a30 236 if ( ppp.pkt.buf[0] != 0xff ) {debug("byte0 != ff\n"); return;}
nixnax 9:0992486d4a30 237 if ( ppp.pkt.buf[1] != 3 ) {debug("byte1 != 3\n"); return;}
nixnax 9:0992486d4a30 238 if ( ppp.pkt.buf[3] != 0x21 ) {debug("byte2 != 21\n"); return;}
nixnax 9:0992486d4a30 239 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 240 switch (packetType) {
nixnax 9:0992486d4a30 241 case 0xc0: LCPframe(); break;
nixnax 9:0992486d4a30 242 case 0x80: IPCPframe(); break;
nixnax 9:0992486d4a30 243 case 0x00: IPframe(); break;
nixnax 9:0992486d4a30 244 default: xx21frame(); break;
nixnax 9:0992486d4a30 245 }
nixnax 9:0992486d4a30 246 }
nixnax 9:0992486d4a30 247
nixnax 9:0992486d4a30 248 void scanForConnectString() {
nixnax 9:0992486d4a30 249 if ( ppp.online==0 ) {
nixnax 9:0992486d4a30 250 char * clientFound = strstr( rxbuf, "CLIENTCLIENT" ); // look for PC string
nixnax 9:0992486d4a30 251 if( clientFound ) {
nixnax 9:0992486d4a30 252 strcpy( clientFound, "FOUND!FOUND!" ); // overwrite so we don't get fixated
nixnax 9:0992486d4a30 253 pc.printf("CLIENTSERVER"); // respond to PC
nixnax 9:0992486d4a30 254 ppp.online=1; // we can stop looking for the string
nixnax 9:0992486d4a30 255 debug("Connect string found\n");
nixnax 9:0992486d4a30 256 }
nixnax 9:0992486d4a30 257 }
nixnax 9:0992486d4a30 258 }
nixnax 9:0992486d4a30 259
nixnax 0:2cf4880c312a 260 int main()
nixnax 0:2cf4880c312a 261 {
nixnax 9:0992486d4a30 262 pc.baud(9600);
nixnax 4:a469050d5b80 263 xx.baud(115200);
nixnax 9:0992486d4a30 264 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 4:a469050d5b80 265
nixnax 9:0992486d4a30 266 pppInitStruct(); // initialize all the PPP properties
nixnax 4:a469050d5b80 267
nixnax 9:0992486d4a30 268 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 4:a469050d5b80 269
nixnax 9:0992486d4a30 270 int frameStartIndex, frameEndIndex; int frameBusy=0;
nixnax 4:a469050d5b80 271
nixnax 0:2cf4880c312a 272 while(1) {
nixnax 9:0992486d4a30 273 if ( ppp.online==0 ) scanForConnectString(); // try to connect
nixnax 0:2cf4880c312a 274 while ( pc_readable() ) {
nixnax 1:9e03798d4367 275 int rx = pc_getBuf();
nixnax 9:0992486d4a30 276 wait(0.001);
nixnax 4:a469050d5b80 277 if (frameBusy) {
nixnax 4:a469050d5b80 278 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 279 frameBusy=0; // done gathering frame
nixnax 4:a469050d5b80 280 frameEndIndex=ppp.rx.tail-1; // remember where frame ends
nixnax 4:a469050d5b80 281 void processFrame(int start, int end); // process a received frame
nixnax 4:a469050d5b80 282 processFrame(frameStartIndex, frameEndIndex);
nixnax 4:a469050d5b80 283 }
nixnax 4:a469050d5b80 284 }
nixnax 4:a469050d5b80 285 else {
nixnax 4:a469050d5b80 286 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 287 frameBusy=1; // start gathering frame
nixnax 9:0992486d4a30 288 frameStartIndex=ppp.rx.tail; // remember where frame started
nixnax 4:a469050d5b80 289 }
nixnax 0:2cf4880c312a 290 }
nixnax 4:a469050d5b80 291 }
nixnax 7:ab147f5e97ac 292 }
nixnax 7:ab147f5e97ac 293 }