From owner-freebsd-hackers  Fri May 18  3:42:17 2001
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Date: Fri, 18 May 2001 14:15:13 +0400 (MSD)
From: "Roman V. Palagin" <romanp@unshadow.net>
To: Archie Cobbs <archie@dellroad.org>
Cc: <freebsd-hackers@freebsd.org>
Subject: Re: How to transfer data from netgraph node to user program?
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On May 17, at 1:04pm -0700, Archie Cobbs wrote:

> > The question is: how I can initiate smth. like asynchronous reply (so I
> > can get data via NgRecvMsg later in my prgram)? Or I'm going wrong way and
> > should use another scheme for data transfer? Data size ranges from 10Kb to
> > 500Kb.
>
> Whenever you're ready to send the reply, just create one and send it.

It doesn't work. This is fragment of my code:

user-level program:

	....
	token = NgSendMsg(..., NGM_XXX_SHOW, ...);
	/* XXX not reached until ng_xxx_msg() returns */
	for(;;) {
		...
		error = NgRecvMsg(...)
		...
	}

netgraph node:

/*
 * Process control messages
 */
int
ng_xxx_msg()
{
	....
	case NGM_XXX_SHOW:
		error = ng_xxx_show_data()
		goto out;
	....
out:
	....
	return (error);
}

/*
 * send collected data
 */
int
ng_xxx_show_data()
{
	for(;;) {
		get_next_data_item();
		if (no_more_data)
			break;
		NG_MKRESPONSE()
		error = ng_send_msg()
	}
	return (error);
}

When size of collected data about 10Kb, all works fine. But when I need to
send 400Kb in reply - oops, ng_xxx_show_data() returns ENOBUFS (I think
because ng_socket receive queue is full, nobody reads from socket). So, I
don't understand how I can transfer large amount of data :-\ Any ideas?

                                             - Roman
---
Any opinions in this posting are my own and not those of my present
or previous employers.


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