/*
 * $Id: tx_dgram.c 12583 2006-12-06 05:42:15Z cbiere $
 *
 * Copyright (c) 2002-2003, Raphael Manfredi
 *
 *----------------------------------------------------------------------
 * This file is part of gtk-gnutella.
 *
 *  gtk-gnutella is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  gtk-gnutella is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with gtk-gnutella; if not, write to the Free Software
 *  Foundation, Inc.:
 *      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *----------------------------------------------------------------------
 */

/**
 * @ingroup core
 * @file
 *
 * Network driver -- datagram level.
 *
 * This driver sends datagrams to specified hosts.
 *
 * @author Raphael Manfredi
 * @date 2002-2003
 */

#include "common.h"

RCSID("$Id: tx_dgram.c 12583 2006-12-06 05:42:15Z cbiere $")

#include "bsched.h"
#include "sockets.h"
#include "tx.h"
#include "tx_dgram.h"
#include "hosts.h"
#include "inet.h"

#include "if/core/hosts.h"

#include "lib/misc.h"
#include "lib/tm.h"
#include "lib/walloc.h"
#include "lib/override.h"		/* Must be the last header included */

/*
 * Private attributes for the layer.
 */
struct attr {
	wrap_io_t 	 *wio;			/**< Cached wrapped IO object */
	bio_source_t *bio;			/**< Bandwidth-limited I/O source */
	struct tx_dgram_cb *cb;		/**< Layer-specific callbacks */
};

/**
 * Invoked when the output file descriptor can accept more data.
 */
static void
is_writable(gpointer data, gint unused_source, inputevt_cond_t cond)
{
	txdrv_t *tx = (txdrv_t *) data;

	(void) unused_source;
	g_assert(tx->flags & TX_SERVICE);		/* Servicing enabled */

	if (cond & INPUT_EVENT_EXCEPTION) {
		g_warning("input exception on UDP socket");
		return;
	}

	/*
	 * We can write again on the node's socket.  Service the queue.
	 */

	g_assert(tx->srv_routine);
	tx->srv_routine(tx->srv_arg);
}

/***
 *** Polymorphic routines.
 ***/

/**
 * Initialize the driver.
 *
 * Always succeeds, so never returns NULL.
 */
static gpointer
tx_dgram_init(txdrv_t *tx, gpointer args)
{
	struct attr *attr;
	struct tx_dgram_args *targs = args;

	g_assert(tx);
	g_assert(targs->cb != NULL);
	g_assert(s_udp_listen != NULL || s_udp_listen6 != NULL);

	attr = walloc(sizeof *attr);

	/*
	 * Because we handle servicing of the upper layers explicitely within
	 * the TX stack (i.e. upper layers detect that we were enable to comply
	 * with the whole write and enable us), there is no I/O callback attached
	 * to the I/O source: we only create it to benefit from bandwidth limiting
	 * through calls to bio_sendto().
	 */

	attr->cb = targs->cb;
	attr->wio = targs->wio;
	attr->bio = bsched_source_add(targs->bws, attr->wio, BIO_F_WRITE,
		NULL, NULL);

	tx->opaque = attr;

	g_assert(attr->wio->sendto != NULL);

	return tx;		/* OK */
}

/**
 * Get rid of the driver's private data.
 */
static void
tx_dgram_destroy(txdrv_t *tx)
{
	struct attr *attr = tx->opaque;

	bsched_source_remove(attr->bio);

	wfree(attr, sizeof *attr);
}

static inline gint
tx_dgram_write_error(txdrv_t *tx, const gnet_host_t *to, const char *func)
{
	if (is_temporary_error(errno) || ENOBUFS == errno)
		return 0;

	switch (errno) {
	/*
	 * The following are probably due to bugs in the libc, but this is in
	 * the same vein as write() failing with -1 whereas errno == 0!  Be more
	 * robust against bugs in the components we rely on. --RAM, 09/10/2003
	 */
	case EINPROGRESS:		/* Weird, but seen it -- RAM, 07/10/2003 */
	{
		const struct attr *attr = tx->opaque;
		g_warning("%s(fd=%d) failed with weird errno = %d (%s), "
			"assuming EAGAIN", func, attr->wio->fd(attr->wio), errno,
			g_strerror(errno));
	}
		return 0;
	case EPIPE:
	case ENOSPC:
	case ENOMEM:
	case EINVAL:			/* Seen this with "reserved" IP addresses */
#ifdef EDQUOT
	case EDQUOT:
#endif /* EDQUOT */
	case EFBIG:
	case EIO:
	case EADDRNOTAVAIL:
	case ECONNABORTED:
	case ECONNRESET:
	case ECONNREFUSED:
	case ENETRESET:
	case ENETDOWN:
	case ENETUNREACH:
	case EHOSTDOWN:
	case EHOSTUNREACH:
	case ENOPROTOOPT:
	case EPROTONOSUPPORT:
	case ETIMEDOUT:
	case EACCES:
	case EPERM:
		/*
		 * Don't set TX_ERROR here, we don't care about lost packets.
		 */
		g_warning("UDP write to %s failed: %s",
			gnet_host_to_string(to), g_strerror(errno));
		return -1;
	default:
		{
			int terr = errno;
			time_t t = tm_time();
			tx->flags |= TX_ERROR;				/* This should be fatal! */
			g_error("%s  gtk-gnutella: %s: "
				"UDP write to %s failed with unexpected errno: %d (%s)\n",
				ctime(&t), func, gnet_host_to_string(to),
				terr, g_strerror(terr));
		}
	}

	return 0;		/* Just in case */
}

/**
 * Send buffer datagram to specified destination `to'.
 *
 * @returns amount of bytes written, or -1 on error with errno set.
 */
static ssize_t
tx_dgram_sendto(txdrv_t *tx, const gnet_host_t *to,
	gconstpointer data, size_t len)
{
	ssize_t r;
	struct attr *attr = tx->opaque;

	if (gnet_host_get_port(to) > 0) {
		r = bio_sendto(attr->bio, to, data, len);
	} else {
		errno = EINVAL;
		r = -1;
	}
	if ((ssize_t) -1 == r)
		return tx_dgram_write_error(tx, to, "tx_dgram_sendto");

	if (attr->cb->add_tx_written != NULL)
		attr->cb->add_tx_written(tx->owner, r);

	inet_udp_record_sent(gnet_host_get_addr(to));

	return r;
}

/**
 * Allow servicing of upper TX queue when output fd is ready.
 */
static void
tx_dgram_enable(txdrv_t *tx)
{
	struct attr *attr = tx->opaque;

	bio_add_callback(attr->bio, is_writable, (gpointer) tx);
}

/**
 * Disable servicing of upper TX queue.
 */
static void
tx_dgram_disable(txdrv_t *tx)
{
	struct attr *attr = tx->opaque;

	bio_remove_callback(attr->bio);
}

/**
 * No data buffered at this level: always returns 0.
 */
static size_t
tx_dgram_pending(txdrv_t *unused_tx)
{
	(void) unused_tx;
	return 0;
}

/**
 * Nothing to do.
 */
static void
tx_dgram_flush(txdrv_t *unused_tx)
{
	(void) unused_tx;
}

/**
 * Nothing to do.
 */
static void
tx_dgram_shutdown(txdrv_t *unused_tx)
{
	(void) unused_tx;
}

/**
 * @return the I/O source of this level.
 */
static struct bio_source *
tx_dgram_bio_source(txdrv_t *tx)
{
	struct attr *attr = tx->opaque;

	return attr->bio;
}

static const struct txdrv_ops tx_dgram_ops = {
	tx_dgram_init,			/**< init */
	tx_dgram_destroy,		/**< destroy */
	tx_no_write,			/**< write */
	tx_no_writev,			/**< writev */
	tx_dgram_sendto,		/**< sendto */
	tx_dgram_enable,		/**< enable */
	tx_dgram_disable,		/**< disable */
	tx_dgram_pending,		/**< pending */
	tx_dgram_flush,			/**< flush */
	tx_dgram_shutdown,		/**< shutdown */
	tx_close_noop,			/**< close */
	tx_dgram_bio_source,	/**< bio_source */
};

const struct txdrv_ops *
tx_dgram_get_ops(void)
{
	return &tx_dgram_ops;
}

/* vi: set ts=4 sw=4 cindent: */
