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@28:1aa629be05e7, 2017-01-04 (annotated)

Committer:
nixnax
Date:
Wed Jan 04 02:20:06 2017 +0000
Revision:
28:1aa629be05e7
Parent:
27:78d194dd8799
Child:
29:30de79d658f6
HTTP, UDP and PING now working

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 28:1aa629be05e7 19 Serial xx(USBTX, USBRX); // The USB com port - Set this up as a Dial-Up Modem on your pc
nixnax 28:1aa629be05e7 20 Serial pc(PC_10, PC_11); // debug((((( port - use an additional USB serial port to monitor this
nixnax 0:2cf4880c312a 21
nixnax 19:e53cdee9a33c 22 // the second #define below gets rid of all the debug printfs
nixnax 20:5db9b77b38a6 23 #define debug(x) xx.printf x
nixnax 19:e53cdee9a33c 24 //#define debug(x) {}
nixnax 9:0992486d4a30 25
nixnax 4:a469050d5b80 26 DigitalOut led1(LED1);
nixnax 4:a469050d5b80 27
nixnax 4:a469050d5b80 28 #define FRAME_7E (0x7e)
nixnax 19:e53cdee9a33c 29 #define BUFLEN (1<<14)
nixnax 20:5db9b77b38a6 30 char rxbuf[BUFLEN];
nixnax 17:4918c893d802 31 char frbuf[6000]; // buffer for ppp frame
nixnax 0:2cf4880c312a 32
nixnax 4:a469050d5b80 33 struct {
nixnax 4:a469050d5b80 34 int online;
nixnax 26:11f4eb2663a7 35 int ident;
nixnax 28:1aa629be05e7 36 int sync;
nixnax 28:1aa629be05e7 37 int seq;
nixnax 4:a469050d5b80 38 struct {
nixnax 20:5db9b77b38a6 39 char * buf;
nixnax 15:b0154c910143 40 volatile int head;
nixnax 20:5db9b77b38a6 41 volatile int tail;
nixnax 9:0992486d4a30 42 int total;
nixnax 4:a469050d5b80 43 } rx; // serial port buffer
nixnax 4:a469050d5b80 44 struct {
nixnax 6:fba4c2e817b8 45 int id;
nixnax 4:a469050d5b80 46 int len;
nixnax 4:a469050d5b80 47 int crc;
nixnax 4:a469050d5b80 48 char * buf;
nixnax 4:a469050d5b80 49 } pkt; // ppp buffer
nixnax 4:a469050d5b80 50 } ppp;
nixnax 0:2cf4880c312a 51
nixnax 26:11f4eb2663a7 52 struct tcpType {
nixnax 26:11f4eb2663a7 53 int connect;
nixnax 26:11f4eb2663a7 54 int ack;
nixnax 26:11f4eb2663a7 55 int seq;
nixnax 26:11f4eb2663a7 56 };
nixnax 26:11f4eb2663a7 57
nixnax 26:11f4eb2663a7 58 tcpType tcp;
nixnax 26:11f4eb2663a7 59
nixnax 26:11f4eb2663a7 60
nixnax 28:1aa629be05e7 61 void pppInitStruct(){ ppp.online=0; ppp.rx.buf=rxbuf; ppp.rx.tail=0; ppp.rx.head=0; ppp.rx.total=0; ppp.pkt.buf=frbuf; ppp.pkt.len=0; ppp.ident=0; ppp.sync=0; ppp.seq=77;}
nixnax 4:a469050d5b80 62
nixnax 4:a469050d5b80 63 int crcG; // frame check sequence (CRC) holder
nixnax 4:a469050d5b80 64 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 65 void crcReset(){crcG=0xffff;} // crc restart
nixnax 9:0992486d4a30 66 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 67
nixnax 0:2cf4880c312a 68 void rxHandler() // serial port receive interrupt handler
nixnax 0:2cf4880c312a 69 {
nixnax 17:4918c893d802 70 while ( pc.readable() ) {
nixnax 20:5db9b77b38a6 71 int hd = (ppp.rx.head+1)&(BUFLEN-1); // increment/wrap
nixnax 20:5db9b77b38a6 72 if ( hd == ppp.rx.tail ) break; // watch for buffer full
nixnax 17:4918c893d802 73 ppp.rx.buf[ppp.rx.head]=pc.getc(); // insert in rx buffer
nixnax 20:5db9b77b38a6 74 ppp.rx.head = hd; // update head pointer
nixnax 15:b0154c910143 75 }
nixnax 0:2cf4880c312a 76 }
nixnax 0:2cf4880c312a 77
nixnax 14:c65831c25aaa 78 int ledState=0;
nixnax 14:c65831c25aaa 79 void led1Toggle(){
nixnax 14:c65831c25aaa 80 ledState = ledState? 0 : 1;
nixnax 14:c65831c25aaa 81 led1 = ledState;
nixnax 14:c65831c25aaa 82 }
nixnax 14:c65831c25aaa 83
nixnax 22:00df34cd4d7e 84 int rxbufNotEmpty() // check if rx buffer has data
nixnax 0:2cf4880c312a 85 {
nixnax 22:00df34cd4d7e 86 __disable_irq(); // critical section start
nixnax 22:00df34cd4d7e 87 int notEmpty = (ppp.rx.head==ppp.rx.tail) ? 0 : 1 ;
nixnax 22:00df34cd4d7e 88 __enable_irq(); // critical section end
nixnax 22:00df34cd4d7e 89 return notEmpty;
nixnax 0:2cf4880c312a 90 }
nixnax 0:2cf4880c312a 91
nixnax 0:2cf4880c312a 92 int pc_getBuf() // get one character from the buffer
nixnax 0:2cf4880c312a 93 {
nixnax 22:00df34cd4d7e 94 if ( rxbufNotEmpty() ) {
nixnax 4:a469050d5b80 95 int x = ppp.rx.buf[ ppp.rx.tail ];
nixnax 20:5db9b77b38a6 96 __disable_irq(); // critical section start
nixnax 22:00df34cd4d7e 97 ppp.rx.tail=(ppp.rx.tail+1)&(BUFLEN-1);
nixnax 20:5db9b77b38a6 98 __enable_irq(); // critical section end
nixnax 0:2cf4880c312a 99 return x;
nixnax 20:5db9b77b38a6 100 } else return -1;
nixnax 0:2cf4880c312a 101 }
nixnax 0:2cf4880c312a 102
nixnax 4:a469050d5b80 103 void scanForConnectString(); // scan for connect attempts from pc
nixnax 1:9e03798d4367 104
nixnax 9:0992486d4a30 105 void processFrame(int start, int end) { // process received frame
nixnax 14:c65831c25aaa 106 led1Toggle(); // change led1 state when frames are received
nixnax 15:b0154c910143 107 if(start==end) { pc.putc(0x7e); return; }
nixnax 9:0992486d4a30 108 crcReset();
nixnax 9:0992486d4a30 109 char * dest = ppp.pkt.buf;
nixnax 9:0992486d4a30 110 ppp.pkt.len=0;
nixnax 9:0992486d4a30 111 int unstuff=0;
nixnax 17:4918c893d802 112 int idx = start;
nixnax 17:4918c893d802 113 while(1) {
nixnax 9:0992486d4a30 114 if (unstuff==0) {
nixnax 17:4918c893d802 115 if (rxbuf[idx]==0x7d) unstuff=1;
nixnax 17:4918c893d802 116 else { *dest = rxbuf[idx]; ppp.pkt.len++; dest++; crcDo(rxbuf[idx]); }
nixnax 12:db0dc91f0231 117 } else { // unstuff
nixnax 17:4918c893d802 118 *dest = rxbuf[idx]^0x20; ppp.pkt.len++; dest++; crcDo(rxbuf[idx]^0x20);
nixnax 9:0992486d4a30 119 unstuff=0;
nixnax 9:0992486d4a30 120 }
nixnax 17:4918c893d802 121 idx = (idx+1) & (BUFLEN-1);
nixnax 17:4918c893d802 122 if (idx == end) break;
nixnax 9:0992486d4a30 123 }
nixnax 9:0992486d4a30 124 ppp.pkt.crc = crcG & 0xffff;
nixnax 9:0992486d4a30 125 if (ppp.pkt.crc == 0xf0b8) { // check for good CRC
nixnax 16:cb0b80c24ba2 126 void determinePacketType(); // declaration only
nixnax 9:0992486d4a30 127 determinePacketType();
nixnax 12:db0dc91f0231 128 } else { // crc error
nixnax 15:b0154c910143 129 debug(("CRC is %x Len is %d\n",ppp.pkt.crc,ppp.pkt.len));
nixnax 15:b0154c910143 130 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 15:b0154c910143 131 debug(("\n"));
nixnax 9:0992486d4a30 132 }
nixnax 9:0992486d4a30 133 }
nixnax 9:0992486d4a30 134
nixnax 11:f58998c24f0b 135 void dumpFrame() {
nixnax 16:cb0b80c24ba2 136 for(int i=0;i<ppp.pkt.len;i++) debug(("%02x ", ppp.pkt.buf[i]));
nixnax 16:cb0b80c24ba2 137 debug((" C=%02x %02x L=%d\n", ppp.pkt.crc&0xff, (ppp.pkt.crc>>8)&0xff, ppp.pkt.len));
nixnax 16:cb0b80c24ba2 138 }
nixnax 16:cb0b80c24ba2 139
nixnax 16:cb0b80c24ba2 140 void hdlcPut(int ch) { // do hdlc handling of special (flag) characters
nixnax 16:cb0b80c24ba2 141 if ( (ch<0x20) || (ch==0x7d) || (ch==0x7e) ) { pc.putc(0x7d); pc.putc(ch^0x20); } else { pc.putc(ch); }
nixnax 11:f58998c24f0b 142 }
nixnax 9:0992486d4a30 143
nixnax 9:0992486d4a30 144 void sendFrame(){
nixnax 17:4918c893d802 145 int crc = crcBuf(ppp.pkt.buf, ppp.pkt.len-2); // update crc
nixnax 12:db0dc91f0231 146 ppp.pkt.buf[ ppp.pkt.len-2 ] = (~crc>>0); // fcs lo (crc)
nixnax 12:db0dc91f0231 147 ppp.pkt.buf[ ppp.pkt.len-1 ] = (~crc>>8); // fcs hi (crc)
nixnax 16:cb0b80c24ba2 148 pc.putc(0x7e); // hdlc start-of-frame "flag"
nixnax 16:cb0b80c24ba2 149 for(int i=0;i<ppp.pkt.len;i++) hdlcPut( ppp.pkt.buf[i] );
nixnax 16:cb0b80c24ba2 150 pc.putc(0x7e); // hdlc end-of-frame "flag"
nixnax 9:0992486d4a30 151 }
nixnax 9:0992486d4a30 152
nixnax 9:0992486d4a30 153 void ipRequestHandler(){
nixnax 15:b0154c910143 154 debug(("IPCP Conf "));
nixnax 9:0992486d4a30 155 if ( ppp.pkt.buf[7] != 4 ) {
nixnax 15:b0154c910143 156 debug(("Rej\n")); // reject if any options are requested
nixnax 9:0992486d4a30 157 ppp.pkt.buf[4]=4;
nixnax 9:0992486d4a30 158 sendFrame();
nixnax 9:0992486d4a30 159 } else {
nixnax 15:b0154c910143 160 debug(("Ack\n"));
nixnax 9:0992486d4a30 161 ppp.pkt.buf[4]=2; // ack the minimum
nixnax 9:0992486d4a30 162 sendFrame(); // acknowledge
nixnax 15:b0154c910143 163 debug(("IPCP Ask\n"));
nixnax 9:0992486d4a30 164 // send our own request now
nixnax 12:db0dc91f0231 165 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 166 ppp.pkt.buf[5]++; // next sequence
nixnax 9:0992486d4a30 167 sendFrame(); // this is our request
nixnax 9:0992486d4a30 168 }
nixnax 9:0992486d4a30 169 }
nixnax 9:0992486d4a30 170
nixnax 15:b0154c910143 171 void ipAckHandler(){ debug(("IPCP Grant\n")); }
nixnax 9:0992486d4a30 172
nixnax 15:b0154c910143 173 void ipNackHandler(){ debug(("IPCP Nack\n")); }
nixnax 9:0992486d4a30 174
nixnax 15:b0154c910143 175 void ipDefaultHandler(){ debug(("IPCP Other\n")); }
nixnax 9:0992486d4a30 176
nixnax 9:0992486d4a30 177 void IPCPframe() {
nixnax 9:0992486d4a30 178 int code = ppp.pkt.buf[4]; // packet type is here
nixnax 9:0992486d4a30 179 switch (code) {
nixnax 9:0992486d4a30 180 case 1: ipRequestHandler(); break;
nixnax 9:0992486d4a30 181 case 2: ipAckHandler(); break;
nixnax 9:0992486d4a30 182 case 3: ipNackHandler(); break;
nixnax 9:0992486d4a30 183 default: ipDefaultHandler();
nixnax 9:0992486d4a30 184 }
nixnax 9:0992486d4a30 185 }
nixnax 9:0992486d4a30 186
nixnax 10:74f8233f72c0 187 void UDPpacket() {
nixnax 12:db0dc91f0231 188 char * udpPkt = ppp.pkt.buf+4; // udp packet start
nixnax 16:cb0b80c24ba2 189 int headerSizeIP = (( udpPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 190 char * udpBlock = udpPkt + headerSizeIP; // udp info start
nixnax 12:db0dc91f0231 191 char * udpSrc = udpBlock; // source port
nixnax 12:db0dc91f0231 192 char * udpDst = udpBlock+2; // destination port
nixnax 12:db0dc91f0231 193 char * udpLen = udpBlock+4; // udp data length
nixnax 12:db0dc91f0231 194 char * udpInf = udpBlock+8; // actual start of info
nixnax 12:db0dc91f0231 195 int srcPort = (udpSrc[0]<<8) | udpSrc[1];
nixnax 12:db0dc91f0231 196 int dstPort = (udpDst[0]<<8) | udpDst[1];
nixnax 12:db0dc91f0231 197 char * srcIP = udpPkt+12; // udp src addr
nixnax 12:db0dc91f0231 198 char * dstIP = udpPkt+16; // udp dst addr
nixnax 12:db0dc91f0231 199 #define UDP_HEADER_SIZE 8
nixnax 12:db0dc91f0231 200 int udpLength = ((udpLen[0]<<8) | udpLen[1]) - UDP_HEADER_SIZE; // size of the actual udp data
nixnax 15:b0154c910143 201 debug(("UDP %d.%d.%d.%d:%d ", srcIP[0],srcIP[1],srcIP[2],srcIP[3],srcPort));
nixnax 15:b0154c910143 202 debug(("%d.%d.%d.%d:%d ", dstIP[1],dstIP[1],dstIP[1],dstIP[1],dstPort));
nixnax 15:b0154c910143 203 debug(("Len %d ", udpLength));
nixnax 13:d882b8a042b4 204 int printSize = udpLength; if (printSize > 20) printSize = 20; // print only first 20 characters
nixnax 16:cb0b80c24ba2 205 for (int i=0; i<printSize; i++) { char ch = udpInf[i]; if (ch>31 && ch<127) { debug(("%c", ch)); } else { debug(("_")); } }
nixnax 15:b0154c910143 206 debug(("\n"));
nixnax 12:db0dc91f0231 207 }
nixnax 11:f58998c24f0b 208
nixnax 11:f58998c24f0b 209 int dataCheckSum(char * ptr, int len) {
nixnax 23:af88d429bed1 210 int sum=0; int placeHolder;
nixnax 25:0b0450e1b08b 211 if (len&1) { placeHolder = ptr[len-1]; ptr[len-1]=0; } // when length is odd zero stuff
nixnax 11:f58998c24f0b 212 for (int i=0;i<len/2;i++) {
nixnax 25:0b0450e1b08b 213 int hi = *ptr; ptr++; int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 214 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 215 sum = sum + val;
nixnax 11:f58998c24f0b 216 }
nixnax 11:f58998c24f0b 217 sum = sum + (sum>>16);
nixnax 25:0b0450e1b08b 218 if (len&1) { ptr[len-1] = placeHolder; } // restore the last byte for odd lengths
nixnax 12:db0dc91f0231 219 return ~sum;
nixnax 11:f58998c24f0b 220 }
nixnax 11:f58998c24f0b 221
nixnax 11:f58998c24f0b 222 void headerCheckSum() {
nixnax 11:f58998c24f0b 223 int len =(ppp.pkt.buf[4]&0xf)*4; // length of header in bytes
nixnax 11:f58998c24f0b 224 char * ptr = ppp.pkt.buf+4; // start of ip packet
nixnax 11:f58998c24f0b 225 int sum=0;
nixnax 11:f58998c24f0b 226
nixnax 11:f58998c24f0b 227 for (int i=0;i<len/2;i++) {
nixnax 11:f58998c24f0b 228 int hi = *ptr; ptr++;
nixnax 11:f58998c24f0b 229 int lo = *ptr; ptr++;
nixnax 11:f58998c24f0b 230 int val = ( lo & 0xff ) | ( (hi<<8) & 0xff00 );
nixnax 11:f58998c24f0b 231 sum = sum + val;
nixnax 11:f58998c24f0b 232 }
nixnax 11:f58998c24f0b 233 sum = sum + (sum>>16);
nixnax 11:f58998c24f0b 234 sum = ~sum;
nixnax 11:f58998c24f0b 235 ppp.pkt.buf[14]= (sum>>8);
nixnax 11:f58998c24f0b 236 ppp.pkt.buf[15]= (sum );
nixnax 9:0992486d4a30 237 }
nixnax 9:0992486d4a30 238
nixnax 11:f58998c24f0b 239 void ICMPpacket() { // internet control message protocol
nixnax 12:db0dc91f0231 240 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 12:db0dc91f0231 241 char * pktLen = ipPkt+2;
nixnax 12:db0dc91f0231 242 int packetLength = (pktLen[0]<<8) | pktLen[1]; // icmp packet length
nixnax 16:cb0b80c24ba2 243 int headerSizeIP = (( ipPkt[0]&0xf)*4);
nixnax 16:cb0b80c24ba2 244 char * icmpType = ipPkt + headerSizeIP; // icmp data start
nixnax 13:d882b8a042b4 245 char * icmpSum = icmpType+2; // icmp checksum
nixnax 13:d882b8a042b4 246
nixnax 12:db0dc91f0231 247 #define ICMP_TYPE_PING_REQUEST 8
nixnax 12:db0dc91f0231 248 if ( icmpType[0] == ICMP_TYPE_PING_REQUEST ) {
nixnax 12:db0dc91f0231 249 char * ipTTL = ipPkt+8; // time to live
nixnax 12:db0dc91f0231 250 ipTTL[0]--; // decrement time to live
nixnax 12:db0dc91f0231 251 char * srcAdr = ipPkt+12;
nixnax 12:db0dc91f0231 252 char * dstAdr = ipPkt+16;
nixnax 18:3e35de1bc877 253 int icmpIdent = (icmpType[4]<<8)|icmpType[5];
nixnax 18:3e35de1bc877 254 int icmpSequence = (icmpType[6]<<8)|icmpType[7];
nixnax 25:0b0450e1b08b 255 debug(("ICMP PING %d.%d.%d.d %d.%d.%d.%d ", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3],dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]));
nixnax 25:0b0450e1b08b 256 debug(("Ident %04x Sequence %04d ",icmpIdent,icmpSequence));
nixnax 11:f58998c24f0b 257 char src[4]; char dst[4];
nixnax 12:db0dc91f0231 258 memcpy(src, srcAdr,4);
nixnax 12:db0dc91f0231 259 memcpy(dst, dstAdr,4);
nixnax 12:db0dc91f0231 260 memcpy(srcAdr, dst,4);
nixnax 12:db0dc91f0231 261 memcpy(dstAdr, src,4); // swap src & dest ip
nixnax 12:db0dc91f0231 262 char * chkSum = ipPkt+10;
nixnax 12:db0dc91f0231 263 chkSum[0]=0; chkSum[1]=0;
nixnax 12:db0dc91f0231 264 headerCheckSum(); // new ip header checksum
nixnax 12:db0dc91f0231 265 #define ICMP_TYPE_ECHO_REPLY 0
nixnax 16:cb0b80c24ba2 266 icmpType[0]=ICMP_TYPE_ECHO_REPLY; // icmp echo reply
nixnax 12:db0dc91f0231 267 icmpSum[0]=0; icmpSum[1]=0; // zero the checksum for recalculation
nixnax 16:cb0b80c24ba2 268 int icmpLength = packetLength - headerSizeIP; // length of ICMP data portion
nixnax 16:cb0b80c24ba2 269 int sum = dataCheckSum( icmpType, icmpLength); // this checksum on icmp data portion
nixnax 12:db0dc91f0231 270 icmpSum[0]=sum>>8; icmpSum[1]=sum; // new checksum for ICMP data portion
nixnax 16:cb0b80c24ba2 271
nixnax 16:cb0b80c24ba2 272 int printSize = icmpLength-8; // exclude size of icmp header
nixnax 25:0b0450e1b08b 273 char * icmpData = icmpType+8; // the actual payload data is after the header
nixnax 25:0b0450e1b08b 274 if (printSize > 10) printSize = 10; // print up to 20 characters
nixnax 25:0b0450e1b08b 275 for (int i=0; i<printSize; i++) { char ch = icmpData[i]; if (ch>31 && ch<127) { debug(("%c",ch)); } else { debug(("_")); }}
nixnax 25:0b0450e1b08b 276 debug(("\n"));
nixnax 25:0b0450e1b08b 277
nixnax 15:b0154c910143 278 sendFrame(); // reply to the ping
nixnax 25:0b0450e1b08b 279
nixnax 12:db0dc91f0231 280 } else {
nixnax 15:b0154c910143 281 debug(("ICMP type=%d \n", icmpType[0]));
nixnax 11:f58998c24f0b 282 }
nixnax 11:f58998c24f0b 283 }
nixnax 11:f58998c24f0b 284
nixnax 11:f58998c24f0b 285 void IGMPpacket() { // internet group management protocol
nixnax 15:b0154c910143 286 debug(("IGMP type=%d \n", ppp.pkt.buf[28]));
nixnax 11:f58998c24f0b 287 }
nixnax 11:f58998c24f0b 288
nixnax 26:11f4eb2663a7 289
nixnax 26:11f4eb2663a7 290 void dumpHeaderIP () {
nixnax 26:11f4eb2663a7 291 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 292 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 293 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 294 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 295 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 296 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 297 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 298 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 299 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 300 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 301 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 302 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 303 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 304
nixnax 26:11f4eb2663a7 305 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 306 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 307 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 308 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 309 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 310 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 311 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 312 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 313 int protocolIP = protocol[0];
nixnax 26:11f4eb2663a7 314 int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 26:11f4eb2663a7 315 char srcIP [16]; snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 26:11f4eb2663a7 316 char dstIP [16]; snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 26:11f4eb2663a7 317 debug(("IP %s %s v%d h%d d%d e%d L%d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength));
nixnax 28:1aa629be05e7 318 if(0) { debug(("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP)); }
nixnax 26:11f4eb2663a7 319 }
nixnax 26:11f4eb2663a7 320
nixnax 26:11f4eb2663a7 321 void dumpHeaderTCP() {
nixnax 26:11f4eb2663a7 322 int ipHdrLen = (ppp.pkt.buf[4]&0xf)*4; // overall length of ip packet
nixnax 26:11f4eb2663a7 323
nixnax 26:11f4eb2663a7 324 char * s = ppp.pkt.buf+4+ipHdrLen; // start of tcp packet
nixnax 26:11f4eb2663a7 325 char * seqtcp = s + 4; // 4 bytes
nixnax 26:11f4eb2663a7 326 char * acktcp = s + 8; // 4 bytes
nixnax 26:11f4eb2663a7 327 char * flagbitstcp = s + 12; // 9 bits
nixnax 26:11f4eb2663a7 328 int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 26:11f4eb2663a7 329 int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 26:11f4eb2663a7 330 int flags = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 26:11f4eb2663a7 331
nixnax 26:11f4eb2663a7 332 int idx = 0; char flagInfo [40];
nixnax 26:11f4eb2663a7 333 if (flags & (1<<0)) idx=snprintf(flagInfo+idx,40, "FIN "); if (flags & (1<<1)) idx=snprintf(flagInfo+idx,40, "SYN ");
nixnax 26:11f4eb2663a7 334 if (flags & (1<<2)) idx=snprintf(flagInfo+idx,40, "RST "); if (flags & (1<<3)) idx=snprintf(flagInfo+idx,40, "PSH ");
nixnax 26:11f4eb2663a7 335 if (flags & (1<<4)) idx=snprintf(flagInfo+idx,40, "ACK "); if (flags & (1<<5)) idx=snprintf(flagInfo+idx,40, "URG ");
nixnax 26:11f4eb2663a7 336 if (flags & (1<<6)) idx=snprintf(flagInfo+idx,40, "ECE "); if (flags & (1<<7)) idx=snprintf(flagInfo+idx,40, "CWR ");
nixnax 26:11f4eb2663a7 337 if (flags & (1<<8)) idx=snprintf(flagInfo+idx,40, "NS ");
nixnax 26:11f4eb2663a7 338
nixnax 28:1aa629be05e7 339 if(0) { debug(("Flag %s Seq %08x Ack %08x ", flagInfo, seq, ack)); }
nixnax 10:74f8233f72c0 340 }
nixnax 10:74f8233f72c0 341
nixnax 26:11f4eb2663a7 342 void tcpHandler() {
nixnax 26:11f4eb2663a7 343
nixnax 26:11f4eb2663a7 344 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 345 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 346
nixnax 26:11f4eb2663a7 347 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 348 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 349 char * pktLen = ipPkt+2; // 2 bytes
nixnax 28:1aa629be05e7 350 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 351 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 352 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 353
nixnax 26:11f4eb2663a7 354 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 355 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 356
nixnax 26:11f4eb2663a7 357 ident[0] = ppp.ident>>8; ident[1] = ppp.ident>>0; // stuff in our ident
nixnax 26:11f4eb2663a7 358
nixnax 28:1aa629be05e7 359 int ipHdrLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 26:11f4eb2663a7 360 char * s = ppp.pkt.buf+4+ipHdrLen; // start of tcp packet
nixnax 26:11f4eb2663a7 361 char * srctcp = s + 0; // 2 bytes
nixnax 26:11f4eb2663a7 362 char * dsttcp = s + 2; // 2 bytes
nixnax 28:1aa629be05e7 363 char * seqtcp = s + 4; // 4 bytes
nixnax 28:1aa629be05e7 364 char * acktcp = s + 8; // 4 bytes
nixnax 28:1aa629be05e7 365 char * offset = s + 12; // 4 bits
nixnax 26:11f4eb2663a7 366 char * flagbitstcp = s + 12; // 9 bits
nixnax 26:11f4eb2663a7 367 char * checksumtcp = s + 16; // 2 bytes
nixnax 26:11f4eb2663a7 368
nixnax 26:11f4eb2663a7 369 int tcpSize = packetLength - headerSizeIP;
nixnax 28:1aa629be05e7 370 int tcpHeaderLen = ((offset[0]>>4)&0x0f)*4; // size of tcp header only
nixnax 28:1aa629be05e7 371 int dataLen = tcpSize - tcpHeaderLen; // data is what's left after the header
nixnax 28:1aa629be05e7 372
nixnax 28:1aa629be05e7 373 int seq = (seqtcp[0]<<24)|(seqtcp[1]<<16)|(seqtcp[2]<<8)|(seqtcp[3]);
nixnax 28:1aa629be05e7 374 int ack = (acktcp[0]<<24)|(acktcp[1]<<16)|(acktcp[2]<<8)|(acktcp[3]);
nixnax 28:1aa629be05e7 375
nixnax 28:1aa629be05e7 376 char * dataStart = s + tcpHeaderLen; // start of data
nixnax 28:1aa629be05e7 377
nixnax 26:11f4eb2663a7 378 int flagsTCP = ((flagbitstcp[0]&1)<<8)|flagbitstcp[1];
nixnax 28:1aa629be05e7 379
nixnax 28:1aa629be05e7 380 #define TCP_FLAG_ACK (1<<4)
nixnax 28:1aa629be05e7 381 #define TCP_FLAG_SYN (1<<1)
nixnax 28:1aa629be05e7 382 #define TCP_FLAG_PSH (1<<3)
nixnax 28:1aa629be05e7 383 #define TCP_FLAG_RST (1<<2)
nixnax 28:1aa629be05e7 384 #define TCP_FLAG_FIN (1<<0)
nixnax 26:11f4eb2663a7 385
nixnax 28:1aa629be05e7 386 // a simple state machine to emulate basie TCP states (e.g. webserver)
nixnax 28:1aa629be05e7 387
nixnax 28:1aa629be05e7 388 int dataLenOld = dataLen; // we are updating data len but still need to use it
nixnax 28:1aa629be05e7 389 dataLen = 0; // reset the data length to prep for a short response
nixnax 28:1aa629be05e7 390
nixnax 28:1aa629be05e7 391 if ( ((flagsTCP & ~TCP_FLAG_ACK) == 0) && ((flagsTCP & TCP_FLAG_ACK) != 0) ) {
nixnax 28:1aa629be05e7 392 if (dataLenOld > 0) { // they sent data in the ack
nixnax 28:1aa629be05e7 393 ack = seq + dataLenOld; // we update to show we know
nixnax 28:1aa629be05e7 394 seq = ppp.seq;
nixnax 28:1aa629be05e7 395 }
nixnax 28:1aa629be05e7 396 else {
nixnax 28:1aa629be05e7 397 if (ack <= ppp.seq) return; // just an empty ack
nixnax 28:1aa629be05e7 398 ppp.seq = ack; // update our count
nixnax 28:1aa629be05e7 399 ack = seq;
nixnax 28:1aa629be05e7 400 seq = ppp.seq;
nixnax 28:1aa629be05e7 401 }
nixnax 28:1aa629be05e7 402 }
nixnax 28:1aa629be05e7 403 else if ( (flagsTCP & TCP_FLAG_FIN) != 0 ) { // got FIN
nixnax 28:1aa629be05e7 404 flagbitstcp[1] |= TCP_FLAG_ACK; // do a syn-ack
nixnax 28:1aa629be05e7 405 ack = seq;
nixnax 28:1aa629be05e7 406 seq = ppp.seq;
nixnax 28:1aa629be05e7 407 }
nixnax 28:1aa629be05e7 408 else if ( (flagsTCP & TCP_FLAG_SYN) != 0 ) { // got SYN
nixnax 28:1aa629be05e7 409 flagbitstcp[1] |= TCP_FLAG_ACK; // do a syn-ack
nixnax 28:1aa629be05e7 410 ack = seq + 1;
nixnax 28:1aa629be05e7 411 seq = ppp.seq-1;
nixnax 28:1aa629be05e7 412 }
nixnax 28:1aa629be05e7 413 else if ( (flagsTCP & TCP_FLAG_PSH) != 0 ) { // respond to push with ack
nixnax 28:1aa629be05e7 414 flagbitstcp[1] = TCP_FLAG_ACK;
nixnax 28:1aa629be05e7 415 int temp = ack;
nixnax 28:1aa629be05e7 416 ack = seq + dataLenOld;
nixnax 28:1aa629be05e7 417 ppp.seq = temp;
nixnax 28:1aa629be05e7 418 seq = temp;
nixnax 28:1aa629be05e7 419 if ( strncmp(dataStart, "GET / HTTP/1.1", 14) == 0) { // check for web client
nixnax 28:1aa629be05e7 420 dataLen = 3*32; // extend the data
nixnax 28:1aa629be05e7 421 memset(dataStart,0, dataLen );
nixnax 28:1aa629be05e7 422 sprintf(dataStart,"HTTP/1.1 200 OK\r\nTransfer-Encoding: chunked; charset=utf-8\r\nF\r\nmbed-PPP-Blinky\r\n\r\n0\r\n\r\n");
nixnax 28:1aa629be05e7 423 }
nixnax 28:1aa629be05e7 424 }
nixnax 28:1aa629be05e7 425
nixnax 28:1aa629be05e7 426 // now we have to redo all the header sizes
nixnax 28:1aa629be05e7 427
nixnax 28:1aa629be05e7 428 int newPacketSize = headerSizeIP + tcpHeaderLen + dataLen;
nixnax 28:1aa629be05e7 429 pktLen[0] = (newPacketSize>>8); pktLen[1]=newPacketSize; // ip total packet size
nixnax 28:1aa629be05e7 430 ppp.pkt.len = newPacketSize+6; // ppp packet length
nixnax 28:1aa629be05e7 431 tcpSize = tcpHeaderLen + dataLen; // tcp packet size
nixnax 26:11f4eb2663a7 432
nixnax 28:1aa629be05e7 433 // redo all the header stuff
nixnax 28:1aa629be05e7 434
nixnax 28:1aa629be05e7 435 acktcp[0]=ack>>24; acktcp[1]=ack>>16; acktcp[2]=ack>>8; acktcp[3]=ack>>0; // save ack
nixnax 28:1aa629be05e7 436 seqtcp[0]=seq>>24; seqtcp[1]=seq>>16; seqtcp[2]=seq>>8; seqtcp[3]=seq>>0; // save seq
nixnax 26:11f4eb2663a7 437
nixnax 28:1aa629be05e7 438 char src[4]; char dst[4]; memcpy(src, srcAdr,4); memcpy(dst, dstAdr,4);
nixnax 28:1aa629be05e7 439 memcpy(srcAdr, dst,4); memcpy(dstAdr, src,4); // swap ip address source/dest
nixnax 26:11f4eb2663a7 440 char psrc[2]; char pdst[2]; memcpy(psrc, srctcp,2); memcpy(pdst, dsttcp,2);
nixnax 26:11f4eb2663a7 441 memcpy(srctcp, pdst,2); memcpy(dsttcp, psrc,2); // swap ip port source/dest
nixnax 28:1aa629be05e7 442
nixnax 28:1aa629be05e7 443 headercheck[0]=0; headercheck[1]=0; headerCheckSum(); // redo the ip header checksum
nixnax 26:11f4eb2663a7 444 char pseudoHeader[12]; int sum; char temp[12]; // for the terrible pseudoheader checksum
nixnax 26:11f4eb2663a7 445 memcpy( pseudoHeader+0, srcAdr, 8); // source and destination addresses.
nixnax 26:11f4eb2663a7 446 pseudoHeader[8]=0; pseudoHeader[9]=protocol[0];
nixnax 26:11f4eb2663a7 447 pseudoHeader[10]=tcpSize>>8; pseudoHeader[11]=tcpSize;
nixnax 26:11f4eb2663a7 448 memcpy(temp, s-12, 12); // keep a copy
nixnax 26:11f4eb2663a7 449 memcpy( s-12, pseudoHeader, 12); // put the header on the tcp packet
nixnax 26:11f4eb2663a7 450 checksumtcp[0]=0; checksumtcp[1]=0;
nixnax 28:1aa629be05e7 451 sum=dataCheckSum(s-12,tcpSize+12); // update TCP checksum
nixnax 26:11f4eb2663a7 452 checksumtcp[0]=sum>>8; checksumtcp[1]=sum;
nixnax 26:11f4eb2663a7 453 memcpy( s-12, temp, 12); // overwrite the pseudoheader
nixnax 26:11f4eb2663a7 454 sendFrame(); // return the TCP packet
nixnax 26:11f4eb2663a7 455 }
nixnax 26:11f4eb2663a7 456
nixnax 26:11f4eb2663a7 457 void dumpDataTCP() {
nixnax 26:11f4eb2663a7 458 int ipPktLen = (ppp.pkt.buf[6]<<8)|ppp.pkt.buf[7]; // overall length of ip packet
nixnax 26:11f4eb2663a7 459 int ipHeaderLen = (ppp.pkt.buf[4]&0xf)*4; // length of ip header
nixnax 26:11f4eb2663a7 460 int tcpHeaderLen = ((ppp.pkt.buf[4+ipHeaderLen+12]>>4)&0xf)*4;; // length of tcp header
nixnax 26:11f4eb2663a7 461 int dataLen = ipPktLen - ipHeaderLen - tcpHeaderLen; // data is what's left after the two headers
nixnax 28:1aa629be05e7 462 if(0) { debug(("TCP %d ipHeader %d tcpHeader %d Data %d\n", ipPktLen, ipHeaderLen, tcpHeaderLen, dataLen)); } // 1 for more verbose
nixnax 28:1aa629be05e7 463 if (dataLen > 0) { debug(("%s\n",ppp.pkt.buf+4+ipHeaderLen+tcpHeaderLen)); } // show the data
nixnax 26:11f4eb2663a7 464 }
nixnax 26:11f4eb2663a7 465
nixnax 26:11f4eb2663a7 466 void TCPpacket(){
nixnax 26:11f4eb2663a7 467 char * ipPkt = ppp.pkt.buf+4; // ip packet start
nixnax 26:11f4eb2663a7 468 char * version = ipPkt; // top 4 bits
nixnax 26:11f4eb2663a7 469 char * ihl = ipPkt; // bottom 4 bits
nixnax 26:11f4eb2663a7 470 char * dscp = ipPkt+1; // top 6 bits
nixnax 26:11f4eb2663a7 471 char * ecn = ipPkt+1; // lower 2 bits
nixnax 26:11f4eb2663a7 472 char * pktLen = ipPkt+2; // 2 bytes
nixnax 26:11f4eb2663a7 473 char * ident = ipPkt+4; // 2 bytes
nixnax 26:11f4eb2663a7 474 char * flags = ipPkt+6; // 2 bits
nixnax 26:11f4eb2663a7 475 char * ttl = ipPkt+8; // 1 byte
nixnax 26:11f4eb2663a7 476 char * protocol = ipPkt+9; // 1 byte
nixnax 26:11f4eb2663a7 477 char * headercheck= ipPkt+10; // 2 bytes
nixnax 26:11f4eb2663a7 478 char * srcAdr = ipPkt+12; // 4 bytes
nixnax 26:11f4eb2663a7 479 char * dstAdr = ipPkt+16; // 4 bytes = total of 20 bytes
nixnax 26:11f4eb2663a7 480
nixnax 26:11f4eb2663a7 481 int versionIP = (version[0]>>4)&0xf;
nixnax 26:11f4eb2663a7 482 int headerSizeIP = (ihl[0]&0xf)*4;
nixnax 26:11f4eb2663a7 483 int dscpIP = (dscp[0]>>2)&0x3f;
nixnax 26:11f4eb2663a7 484 int ecnIP = ecn[0]&3;
nixnax 26:11f4eb2663a7 485 int packetLength = (pktLen[0]<<8)|pktLen[1]; // ip total packet length
nixnax 26:11f4eb2663a7 486 int identIP = (ident[0]<<8)|ident[1];
nixnax 26:11f4eb2663a7 487 int flagsIP = flags[0]>>14&3;
nixnax 26:11f4eb2663a7 488 int ttlIP = ttl[0];
nixnax 26:11f4eb2663a7 489 int protocolIP = protocol[0];
nixnax 26:11f4eb2663a7 490 int checksumIP = (headercheck[0]<<8)|headercheck[1];
nixnax 26:11f4eb2663a7 491 char srcIP [16]; snprintf(srcIP,16, "%d.%d.%d.%d", srcAdr[0],srcAdr[1],srcAdr[2],srcAdr[3]);
nixnax 26:11f4eb2663a7 492 char dstIP [16]; snprintf(dstIP,16, "%d.%d.%d.%d", dstAdr[0],dstAdr[1],dstAdr[2],dstAdr[3]);
nixnax 26:11f4eb2663a7 493 debug(("IP %s %s v%d h%d d%d e%d L%d ",srcIP,dstIP,versionIP,headerSizeIP,dscpIP,ecnIP,packetLength));
nixnax 26:11f4eb2663a7 494 debug(("i%04x f%d t%d p%d C%04x\n",identIP,flagsIP,ttlIP,protocolIP,checksumIP));
nixnax 28:1aa629be05e7 495 dumpHeaderTCP();
nixnax 26:11f4eb2663a7 496 dumpDataTCP();
nixnax 26:11f4eb2663a7 497 tcpHandler();
nixnax 11:f58998c24f0b 498 }
nixnax 11:f58998c24f0b 499
nixnax 26:11f4eb2663a7 500 void otherProtocol() { debug(("Other IP protocol")); }
nixnax 26:11f4eb2663a7 501
nixnax 10:74f8233f72c0 502 void IPframe() {
nixnax 10:74f8233f72c0 503 int protocol = ppp.pkt.buf[13];
nixnax 10:74f8233f72c0 504 switch (protocol) {
nixnax 11:f58998c24f0b 505 case 1: ICMPpacket(); break;
nixnax 11:f58998c24f0b 506 case 2: IGMPpacket(); break;
nixnax 11:f58998c24f0b 507 case 17: UDPpacket(); break;
nixnax 11:f58998c24f0b 508 case 6: TCPpacket(); break;
nixnax 11:f58998c24f0b 509 default: otherProtocol();
nixnax 10:74f8233f72c0 510 }
nixnax 10:74f8233f72c0 511 }
nixnax 9:0992486d4a30 512
nixnax 9:0992486d4a30 513 void LCPconfReq() {
nixnax 15:b0154c910143 514 debug(("LCP Config "));
nixnax 9:0992486d4a30 515 if (ppp.pkt.buf[7] != 4) {
nixnax 11:f58998c24f0b 516 ppp.pkt.buf[4]=4; // allow only no options
nixnax 15:b0154c910143 517 debug(("Reject\n"));
nixnax 9:0992486d4a30 518 sendFrame();
nixnax 9:0992486d4a30 519 } else {
nixnax 9:0992486d4a30 520 ppp.pkt.buf[4]=2; // ack zero conf
nixnax 15:b0154c910143 521 debug(("Ack\n"));
nixnax 9:0992486d4a30 522 sendFrame();
nixnax 15:b0154c910143 523 debug(("LCP Ask\n"));
nixnax 11:f58998c24f0b 524 ppp.pkt.buf[4]=1; // request no options
nixnax 9:0992486d4a30 525 sendFrame();
nixnax 9:0992486d4a30 526 }
nixnax 9:0992486d4a30 527 }
nixnax 9:0992486d4a30 528
nixnax 9:0992486d4a30 529 void LCPconfAck() {
nixnax 15:b0154c910143 530 debug(("LCP Ack\n"));
nixnax 9:0992486d4a30 531 }
nixnax 9:0992486d4a30 532
nixnax 9:0992486d4a30 533 void LCPend(){
nixnax 15:b0154c910143 534 debug(("LCP End\n"));
nixnax 12:db0dc91f0231 535 ppp.online=0; // start hunting for connect string again
nixnax 9:0992486d4a30 536 ppp.pkt.buf[4]=6;
nixnax 12:db0dc91f0231 537 sendFrame(); // acknowledge
nixnax 9:0992486d4a30 538 }
nixnax 9:0992486d4a30 539
nixnax 9:0992486d4a30 540 void LCPother(){
nixnax 15:b0154c910143 541 debug(("LCP Other\n"));
nixnax 12:db0dc91f0231 542 dumpFrame();
nixnax 9:0992486d4a30 543 }
nixnax 9:0992486d4a30 544
nixnax 9:0992486d4a30 545 void LCPframe(){
nixnax 9:0992486d4a30 546 int code = ppp.pkt.buf[4];
nixnax 9:0992486d4a30 547 switch (code) {
nixnax 12:db0dc91f0231 548 case 1: LCPconfReq(); break; // config request
nixnax 12:db0dc91f0231 549 case 2: LCPconfAck(); break; // config ack
nixnax 12:db0dc91f0231 550 case 5: LCPend(); break; // end connection
nixnax 12:db0dc91f0231 551 default: LCPother();
nixnax 9:0992486d4a30 552 }
nixnax 9:0992486d4a30 553 }
nixnax 9:0992486d4a30 554
nixnax 12:db0dc91f0231 555 void discardedFrame() {
nixnax 15:b0154c910143 556 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 557 }
nixnax 9:0992486d4a30 558
nixnax 9:0992486d4a30 559 void determinePacketType() {
nixnax 15:b0154c910143 560 if ( ppp.pkt.buf[0] != 0xff ) { debug(("byte0 != ff\n")); return;}
nixnax 15:b0154c910143 561 if ( ppp.pkt.buf[1] != 3 ) { debug(("byte1 != 3\n")); return;}
nixnax 15:b0154c910143 562 if ( ppp.pkt.buf[3] != 0x21 ) { debug(("byte2 != 21\n")); return;}
nixnax 9:0992486d4a30 563 int packetType = ppp.pkt.buf[2];
nixnax 9:0992486d4a30 564 switch (packetType) {
nixnax 12:db0dc91f0231 565 case 0xc0: LCPframe(); break; // link control
nixnax 12:db0dc91f0231 566 case 0x80: IPCPframe(); break; // IP control
nixnax 12:db0dc91f0231 567 case 0x00: IPframe(); break; // IP itself
nixnax 12:db0dc91f0231 568 default: discardedFrame();
nixnax 9:0992486d4a30 569 }
nixnax 9:0992486d4a30 570 }
nixnax 9:0992486d4a30 571
nixnax 9:0992486d4a30 572 void scanForConnectString() {
nixnax 9:0992486d4a30 573 if ( ppp.online==0 ) {
nixnax 15:b0154c910143 574 char * clientFound = strstr( (char *)rxbuf, "CLIENTCLIENT" ); // look for PC string
nixnax 9:0992486d4a30 575 if( clientFound ) {
nixnax 9:0992486d4a30 576 strcpy( clientFound, "FOUND!FOUND!" ); // overwrite so we don't get fixated
nixnax 9:0992486d4a30 577 pc.printf("CLIENTSERVER"); // respond to PC
nixnax 9:0992486d4a30 578 ppp.online=1; // we can stop looking for the string
nixnax 15:b0154c910143 579 debug(("Connect string found\n"));
nixnax 9:0992486d4a30 580 }
nixnax 9:0992486d4a30 581 }
nixnax 9:0992486d4a30 582 }
nixnax 9:0992486d4a30 583
nixnax 26:11f4eb2663a7 584 int myIdent = 0;
nixnax 26:11f4eb2663a7 585
nixnax 0:2cf4880c312a 586 int main()
nixnax 0:2cf4880c312a 587 {
nixnax 14:c65831c25aaa 588 pc.baud(115200); // USB virtual serial port
nixnax 15:b0154c910143 589 xx.baud(115200); // second serial port for debug(((((((( messages
nixnax 9:0992486d4a30 590 xx.puts("\x1b[2J\x1b[HReady\n"); // VT100 code for clear screen & home
nixnax 4:a469050d5b80 591
nixnax 9:0992486d4a30 592 pppInitStruct(); // initialize all the PPP properties
nixnax 4:a469050d5b80 593
nixnax 9:0992486d4a30 594 pc.attach(&rxHandler,Serial::RxIrq); // start the receive handler
nixnax 4:a469050d5b80 595
nixnax 9:0992486d4a30 596 int frameStartIndex, frameEndIndex; int frameBusy=0;
nixnax 4:a469050d5b80 597
nixnax 0:2cf4880c312a 598 while(1) {
nixnax 9:0992486d4a30 599 if ( ppp.online==0 ) scanForConnectString(); // try to connect
nixnax 22:00df34cd4d7e 600 while ( rxbufNotEmpty() ) {
nixnax 1:9e03798d4367 601 int rx = pc_getBuf();
nixnax 4:a469050d5b80 602 if (frameBusy) {
nixnax 4:a469050d5b80 603 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 604 frameBusy=0; // done gathering frame
nixnax 4:a469050d5b80 605 frameEndIndex=ppp.rx.tail-1; // remember where frame ends
nixnax 4:a469050d5b80 606 processFrame(frameStartIndex, frameEndIndex);
nixnax 4:a469050d5b80 607 }
nixnax 4:a469050d5b80 608 }
nixnax 4:a469050d5b80 609 else {
nixnax 4:a469050d5b80 610 if (rx==FRAME_7E) {
nixnax 4:a469050d5b80 611 frameBusy=1; // start gathering frame
nixnax 9:0992486d4a30 612 frameStartIndex=ppp.rx.tail; // remember where frame started
nixnax 4:a469050d5b80 613 }
nixnax 0:2cf4880c312a 614 }
nixnax 4:a469050d5b80 615 }
nixnax 7:ab147f5e97ac 616 }
nixnax 7:ab147f5e97ac 617 }