Thread: HTTP Get request to C Program

I am trying to modify code from the Olimex EasyWeb3 board. It uses an MSP430F149 and a crystal lan cs8900a ethernet controller. There is a sample code for a simple web server. I am interested in modifying the code to use Javascript to request information from the c program.

The problem right now is that the way the code is written it basically has a constant array Webside [ ] that has the code directly written in it. essentially the main code transmits a certain data size of that webside variable. Before it is transmitted, a subroutine searches for specific keys in the data and replaces it with a certain value (AD7% is the specific key, searches for that, and replaces an actual ADC value from one of the ports of the microcontroller). Then it finishes transmitting the rest of the data.

By doing it this way, there is no way I can have user interaction from the web browser. I am trying to make it so that the user can read or write values to specific locations in the microcontroller memory. I know the Javascript to use, but I do not know how those HTTP request interact with the sample code, or how it gets transfered or keeps track of it...

Any suggestions would be helpful.

Attached are the code

Thanks!!!

here are the rest of the attachments

cs8900.c/.h --> contain the ethernet driver information
webside.c --> webpage
tcpip.h/.c --> the TCP/IP stack
easyweb.c/.h --> contain the main program and function HTTPserver() to transmit the webpage


I have looked on the internet about how solve my problem but there isn't much detailed information about it

HTTP Made Really Easy

well, I suppose that if a GET request from the web browser occurs, how is it received by the ethernet controller? Does it automatically get transfer to the RXdatabuffer of the ethernet controller?

Since HTTP is a TCP protocal, there is a connect procedure that must take place, then a GET is sent. It then sits in the RX buffer at the network level waiting for a call to recv() to transfer it to the application level where you can process it. It doesn't just magically appear anywhere you can get at. The network level is oblivious to protocals other than those used to transfer data (UDP / TCP etc.) awareness of HTTP FTP etc. occurs at the application level.

So I read that tutorial and other articles about HTTP protocols....In my case, in the main program (easyweb.c), it essentially setups the ethernet controller, etc... Then it hits the main while loop in which is listens for an incoming TCP-connection, function TCPPassive_Open().

It then hits the DoNetworkStuff() function in tcpip.c , which takes care of the TCP/IP stack. It then jumps to HTTPserver() function which determines if there is a connection and sets everything up to transfer the webpage.

The thing is that it says that "During the first jump to HTTPServer() after connecting, the flag HTTP_SEND_PAGE in register HTTPStatus is clear. It is used to process some special code sections during this first execution of HTTPServer(). The web server checks for any incoming TCP data and discards it. It is assumed that the received data contains a GET request from an Internet browser. Since our server supports only one web page, this request is not evaluated. The server starts just after client connection by sending the web page stored in MCU memory"


So I can trying to determine if I have Javascript in my code that contains a "GET" request, what function is used to acknowledge that there is a request?? I know I'll have to create a function that checks what URI the "GET" request is for, then from there process is to grab whatever values I need.

Can someone help me in the right direction?