How to make a G-WAN servlet close its connection silently without sending any reply

Question

How to have gwan send no reply to some requests, i.e. make a servlet closed silently without building and sending a reply?

It is useful to reduce the out-going bandwidth from the server side.

For collecting data only, there's no need to respond anything to the client.

Answer 1

You can also close the connection from the servlet by doing something like (untested):

#include <sys/socket.h>

char buf[1024];
int s = (int)get_env(argv, CLIENT_SOCKET);
shutdown(s, SHUT_WR);
while(read(s, buf, sizeof(buf)) > 0);
close(s);
return 500;

Then return something like 500 like above so you don't have to build a reply.

Answer 2

You can do that with a gwan connection handler.

I think this is the event that you need to catch on the handler. Since you want the servlet to run then close the connection after.

HDL_BEFORE_WRITE, // after a reply was built, but before it is sent

Here is a sample code for the connection handler. You still need to add your filter. This code will close all requests after the reply was built.

int init(int argc, char *argv[])
{ 
   u32 *states = (u32*)get_env(argv, US_HANDLER_STATES);
   *states =  (1 << HDL_BEFORE_WRITE)
}

int main(int argc, char *argv[])
{
    long state = (long)argv[0];
    if(state == HDL_BEFORE_WRITE)
    {
        return 0; // Close connection
    }
    return(255); // continue G-WAN's default execution path
}