/*
 * detail.c	Process the detail file
 *
 * Version:	$Id: detail.c,v 1.6 2008/01/06 17:32:05 nbk Exp $
 *
 *   This program 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.
 *
 *   This program 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 this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 *
 * Copyright 2007  The FreeRADIUS server project
 * Copyright 2007  Alan DeKok <aland@deployingradius.com>
 */

#include <freeradius-devel/ident.h>
RCSID("$Id: detail.c,v 1.6 2008/01/06 17:32:05 nbk Exp $")

#include <freeradius-devel/radiusd.h>
#include <freeradius-devel/modules.h>
#include <freeradius-devel/detail.h>
#include <freeradius-devel/rad_assert.h>

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

#include <fcntl.h>

#define USEC (1000000)

typedef struct listen_detail_t {
	int		delay_time; /* should be first entry */
	char	*filename;
	VALUE_PAIR	*vps;
	FILE		*fp;
	int		state;
	time_t		timestamp;
	fr_ipaddr_t	client_ip;
	int		load_factor; /* 1..100 */

	int		has_rtt;
	int		srtt;
	int		rttvar;
	struct timeval  last_packet;
	RADCLIENT	detail_client;
} listen_detail_t;


#define STATE_UNOPENED	(0)
#define STATE_UNLOCKED	(1)
#define STATE_HEADER	(2)
#define STATE_READING	(3)
#define STATE_QUEUED	(4)
#define STATE_RUNNING	(5)
#define STATE_NO_REPLY	(6)
#define STATE_REPLIED	(7)

/*
 *	If we're limiting outstanding packets, then mark the response
 *	as being sent.
 */
int detail_send(rad_listen_t *listener, REQUEST *request)
{
	int rtt;
	struct timeval now;
	listen_detail_t *data = listener->data;

	rad_assert(request->listener == listener);
	rad_assert(listener->send == detail_send);

	/*
	 *	This request timed out.  Remember that, and tell the
	 *	caller it's OK to read more "detail" file stuff.
	 */
	if (request->reply->code == 0) {
		radius_signal_self(RADIUS_SIGNAL_SELF_DETAIL);
		data->state = STATE_NO_REPLY;
		return 0;
	}

	/*
	 *	We call gettimeofday a lot.  But here it should be OK,
	 *	because there's nothing else to do.
	 */
	gettimeofday(&now, NULL);

	/*
	 *	If we haven't sent a packet in the last second, reset
	 *	the RTT.
	 */
	now.tv_sec -= 1;
	if (timercmp(&data->last_packet, &now, <)) {
		data->has_rtt = FALSE;
	}
	now.tv_sec += 1;

	/*
	 *	Only one detail packet may be outstanding at a time,
	 *	so it's safe to update some entries in the detail
	 *	structure.
	 *
	 *	We keep smoothed round trip time (SRTT), but not round
	 *	trip timeout (RTO).  We use SRTT to calculate a rough
	 *	load factor.
	 */
	rtt = now.tv_sec - request->received.tv_sec;
	rtt *= USEC;
	rtt += now.tv_usec;
	rtt -= request->received.tv_usec;

	/*
	 *	If we're proxying, the RTT is our processing time,
	 *	plus the network delay there and back, plus the time
	 *	on the other end to process the packet.  Ideally, we
	 *	should remove the network delays from the RTT, but we
	 *	don't know what they are.
	 *
	 *	So, to be safe, we over-estimate the total cost of
	 *	processing the packet.
	 */
	if (!data->has_rtt) {
		data->has_rtt = TRUE;
		data->srtt = rtt;
		data->rttvar = rtt / 2;

	} else {
		data->rttvar -= data->rttvar >> 2;
		data->rttvar += (data->srtt - rtt);
		data->srtt -= data->srtt >> 3;
		data->srtt += rtt >> 3;
	}

	/*
	 *	Calculate the time we wait before sending the next
	 *	packet.
	 *
	 *	rtt / (rtt + delay) = load_factor / 100
	 */
	data->delay_time = (data->srtt * (100 - data->load_factor)) / (data->load_factor);

	DEBUG2("RTT %d\tdelay %d", data->srtt, data->delay_time);

	data->last_packet = now;
	data->state = STATE_REPLIED;

	return 0;
}


/*
 *	Open the detail file, if we can.
 *
 *	FIXME: create it, if it's not already there, so that the main
 *	server select() will wake us up if there's anything to read.
 */
static int detail_open(rad_listen_t *this)
{
	struct stat st;
	char buffer[2048];
	listen_detail_t *data = this->data;

	rad_assert(data->state == STATE_UNOPENED);
	snprintf(buffer, sizeof(buffer), "%s.work", data->filename);

	/*
	 *	Open detail.work first, so we don't lose
	 *	accounting packets.  It's probably better to
	 *	duplicate them than to lose them.
	 *
	 *	Note that we're not writing to the file, but
	 *	we've got to open it for writing in order to
	 *	establish the lock, to prevent rlm_detail from
	 *	writing to it.
	 */
	this->fd = open(buffer, O_RDWR);
	if (this->fd < 0) {
		/*
		 *	Try reading the detail file.  If it
		 *	doesn't exist, we can't do anything.
		 *
		 *	Doing the stat will tell us if the file
		 *	exists, even if we don't have permissions
		 *	to read it.
		 */
		if (stat(data->filename, &st) < 0) {
			return 0;
		}

		/*
		 *	Open it BEFORE we rename it, just to
		 *	be safe...
		 */
		this->fd = open(data->filename, O_RDWR);
		if (this->fd < 0) {
			radlog(L_ERR, "Failed to open %s: %s",
			       data->filename, strerror(errno));
			return 0;
		}

		/*
		 *	Rename detail to detail.work
		 */
		if (rename(data->filename, buffer) < 0) {
			close(this->fd);
			this->fd = -1;
			return 0;
		}
	} /* else detail.work existed, and we opened it */

	rad_assert(data->vps == NULL);

	rad_assert(data->fp == NULL);
	data->fp = fdopen(this->fd, "r");
	if (!data->fp) {
		radlog(L_ERR, "Failed to re-open %s: %s",
		       data->filename, strerror(errno));
		return 0;
	}

	data->state = STATE_UNLOCKED;

	data->client_ip.af = AF_UNSPEC;
	data->timestamp = 0;

	return 1;
}


/*
 *	FIXME: add a configuration "exit when done" so that the detail
 *	file reader can be used as a one-off tool to update stuff.
 *
 *	The time sequence for reading from the detail file is:
 *
 *	t_0		signalled that the server is idle, and we
 *			can read from the detail file.
 *
 *	t_rtt		the packet has been processed successfully,
 *			wait for t_delay to enforce load factor.
 *			
 *	t_rtt + t_delay wait for signal that the server is idle.
 *	
 */
int detail_recv(rad_listen_t *listener,
		RAD_REQUEST_FUNP *pfun, REQUEST **prequest)
{
	char		key[256], value[1024];
	VALUE_PAIR	*vp, **tail;
	RADIUS_PACKET	*packet;
	char		buffer[2048];
	listen_detail_t *data = listener->data;

	switch (data->state) {
		case STATE_UNOPENED:
			rad_assert(listener->fd < 0);
			
			/*
			 *	FIXME: If the file doesn't exist, then
			 *	return "sleep for 1s", to avoid busy
			 *	looping.
			 */
			if (!detail_open(listener)) return 0;

			rad_assert(data->state == STATE_UNLOCKED);
			rad_assert(listener->fd >= 0);

			/* FALL-THROUGH */

			/*
			 *	Try to lock fd.  If we can't, return.
			 *	If we can, continue.  This means that
			 *	the server doesn't block while waiting
			 *	for the lock to open...
			 */
		case STATE_UNLOCKED:
			/*
			 *	Note that we do NOT block waiting for
			 *	the lock.  We've re-named the file
			 *	above, so we've already guaranteed
			 *	that any *new* detail writer will not
			 *	be opening this file.  The only
			 *	purpose of the lock is to catch a race
			 *	condition where the execution
			 *	"ping-pongs" between radiusd &
			 *	radrelay.
			 */
			if (rad_lockfd_nonblock(listener->fd, 0) < 0) {
				return 0;
			}
			/*
			 *	Look for the header
			 */
			data->state = STATE_HEADER;
			data->vps = NULL;

			/* FALL-THROUGH */

		case STATE_HEADER:
		do_header:
			/*
			 *	End of file.  Delete it, and re-set
			 *	everything.
			 */
			if (feof(data->fp)) {
			cleanup:
				snprintf(buffer, sizeof(buffer),
					 "%s.work", data->filename);
				unlink(buffer);
				fclose(data->fp); /* closes listener->fd */
				data->fp = NULL;
				listener->fd = -1;
				data->state = STATE_UNOPENED;
				rad_assert(data->vps == NULL);
				return 0;
			}

			/*
			 *	Else go read something.
			 */
			break;

			/*
			 *	Read more value-pair's, unless we're
			 *	at EOF.  In that case, queue whatever
			 *	we have.
			 */
		case STATE_READING:
			if (!feof(data->fp)) break;
			data->state = STATE_QUEUED;

			/* FALL-THROUGH */

		case STATE_QUEUED:
			goto alloc_packet;

			/*
			 *	We still have an outstanding packet.
			 *	Don't read any more.
			 */
		case STATE_RUNNING:
			return 0;

			/*
			 *	If there's no reply, keep
			 *	retransmitting the current packet
			 *	forever.
			 */
		case STATE_NO_REPLY:
			data->state = STATE_QUEUED;
			goto alloc_packet;
				
			/*
			 *	We have a reply.  Clean up the old
			 *	request, and go read another one.
			 */
		case STATE_REPLIED:
			pairfree(&data->vps);
			data->state = STATE_HEADER;
			goto do_header;
	}
	
	tail = &data->vps;
	while (*tail) tail = &(*tail)->next;

	/*
	 *	Read a header, OR a value-pair.
	 */
	while (fgets(buffer, sizeof(buffer), data->fp)) {
		/*
		 *	Badly formatted file: delete it.
		 *
		 *	FIXME: Maybe flag an error?
		 */
		if (!strchr(buffer, '\n')) {
			pairfree(&data->vps);
			goto cleanup;
		}

		/*
		 *	We're reading VP's, and got a blank line.
		 *	Queue the packet.
		 */
		if ((data->state == STATE_READING) &&
		    (buffer[0] == '\n')) {
			data->state = STATE_QUEUED;
			break;
		}

		/*
		 *	Look for date/time header, and read VP's if
		 *	found.  If not, keep reading lines until we
		 *	find one.
		 */
		if (data->state == STATE_HEADER) {
			int y;

			if (sscanf(buffer, "%*s %*s %*d %*d:%*d:%*d %d", &y)) {
				data->state = STATE_READING;
			}
			continue;
		}

		/*
		 *	We have a full "attribute = value" line.
		 *	If it doesn't look reasonable, skip it.
		 *
		 *	FIXME: print an error for badly formatted attributes?
		 */
		if (sscanf(buffer, "%255s = %1023s", key, value) != 2) {
			continue;
		}

		/*
		 *	Skip non-protocol attributes.
		 */
		if (!strcasecmp(key, "Request-Authenticator")) continue;

		/*
		 *	Set the original client IP address, based on
		 *	what's in the detail file.
		 *
		 *	Hmm... we don't set the server IP address.
		 *	or port.  Oh well.
		 */
		if (!strcasecmp(key, "Client-IP-Address")) {
			data->client_ip.af = AF_INET;
			ip_hton(value, AF_INET, &data->client_ip);
			continue;
		}

		/*
		 *	The original time at which we received the
		 *	packet.  We need this to properly calculate
		 *	Acct-Delay-Time.
		 */
		if (!strcasecmp(key, "Timestamp")) {
			data->timestamp = atoi(value);
			continue;
		}

		/*
		 *	Read one VP.
		 *
		 *	FIXME: do we want to check for non-protocol
		 *	attributes like radsqlrelay does?
		 */
		vp = NULL;
		if ((userparse(buffer, &vp) > 0) &&
		    (vp != NULL)) {
			*tail = vp;
			tail = &(vp->next);
		}
	}

	/*
	 *	Some kind of error.
	 *
	 *	FIXME: Leave the file in-place, and warn the
	 *	administrator?
	 */
	if (ferror(data->fp)) goto cleanup;

	/*
	 *	Process the packet.
	 */
 alloc_packet:
	rad_assert(data->state == STATE_QUEUED);

	/*
	 *	We're done reading the file, but we didn't read
	 *	anything.  Clean up, and don't return anything.
	 */
	if (!data->vps) {
		data->state = STATE_HEADER;
		return 0;
	}

	/*
	 *	Allocate the packet.  If we fail, it's a serious
	 *	problem.
	 */
	packet = rad_alloc(1);
	if (!packet) {
		data->state = STATE_NO_REPLY;	/* try again later */
		return 0;	/* maybe memory will magically free up... */
	}

	memset(packet, 0, sizeof(*packet));
	packet->sockfd = -1;
	packet->src_ipaddr.af = AF_INET;
	packet->src_ipaddr.ipaddr.ip4addr.s_addr = htonl(INADDR_NONE);
	packet->code = PW_ACCOUNTING_REQUEST;
	packet->timestamp = time(NULL);

	/*
	 *	Remember where it came from, so that we don't
	 *	proxy it to the place it came from...
	 */
	if (data->client_ip.af != AF_UNSPEC) {
		packet->src_ipaddr = data->client_ip;
	}

	vp = pairfind(packet->vps, PW_PACKET_SRC_IP_ADDRESS);
	if (vp) {
		packet->src_ipaddr.af = AF_INET;
		packet->src_ipaddr.ipaddr.ip4addr.s_addr = vp->vp_ipaddr;
	} else {
		vp = pairfind(packet->vps, PW_PACKET_SRC_IPV6_ADDRESS);
		if (vp) {
			packet->src_ipaddr.af = AF_INET6;
			memcpy(&packet->src_ipaddr.ipaddr.ip6addr,
			       &vp->vp_ipv6addr, sizeof(vp->vp_ipv6addr));
		}
	}

	vp = pairfind(packet->vps, PW_PACKET_DST_IP_ADDRESS);
	if (vp) {
		packet->dst_ipaddr.af = AF_INET;
		packet->dst_ipaddr.ipaddr.ip4addr.s_addr = vp->vp_ipaddr;
	} else {
		vp = pairfind(packet->vps, PW_PACKET_DST_IPV6_ADDRESS);
		if (vp) {
			packet->dst_ipaddr.af = AF_INET6;
			memcpy(&packet->dst_ipaddr.ipaddr.ip6addr,
			       &vp->vp_ipv6addr, sizeof(vp->vp_ipv6addr));
		}
	}

	/*
	 *	We've got to give SOME value for Id & ports, so that
	 *	the packets can be added to the request queue.
	 *	However, we don't want to keep track of used/unused
	 *	id's and ports, as that's a lot of work.  This hack
	 *	ensures that (if we have real random numbers), that
	 *	there will be a collision on every 2^(16+15+15+24 - 1)
	 *	packets, on average.  That means we can read 2^37
	 *	packets before having a collision, which means it's
	 *	effectively impossible.
	 */
	packet->id = fr_rand() & 0xffff;
	packet->src_port = 1024 + (fr_rand() & 0x7fff);
	packet->dst_port = 1024 + (fr_rand() & 0x7fff);

	packet->dst_ipaddr.af = AF_INET;
	packet->dst_ipaddr.ipaddr.ip4addr.s_addr = htonl((INADDR_LOOPBACK & ~0xffffff) | (fr_rand() & 0xffffff));

	/*
	 *	If everything's OK, this is a waste of memory.
	 *	Otherwise, it lets us re-send the original packet
	 *	contents, unmolested.
	 */
	packet->vps = paircopy(data->vps);

	/*
	 *	Look for Acct-Delay-Time, and update
	 *	based on Acct-Delay-Time += (time(NULL) - timestamp)
	 */
	vp = pairfind(packet->vps, PW_ACCT_DELAY_TIME);
	if (!vp) {
		vp = paircreate(PW_ACCT_DELAY_TIME, PW_TYPE_INTEGER);
		rad_assert(vp != NULL);
		pairadd(&packet->vps, vp);
	}
	if (data->timestamp != 0) {
		vp->vp_integer += time(NULL) - data->timestamp;
	}

	*pfun = rad_accounting;

	if (debug_flag) {
		printf("detail_recv: Read packet from %s\n", data->filename);
		for (vp = packet->vps; vp; vp = vp->next) {
			putchar('\t');
			vp_print(stdout, vp);
			putchar('\n');
		}
	}

	/*
	 *	FIXME: many of these checks may not be necessary when
	 *	reading from the detail file.
	 *
	 *	Try again later...
	 */
	if (!received_request(listener, packet, prequest,
			      &data->detail_client)) {
		rad_free(&packet);
		data->state = STATE_NO_REPLY;	/* try again later */
		return 0;
	}

	data->state = STATE_RUNNING;

	return 1;
}


/*
 *	Free detail-specific stuff.
 */
void detail_free(rad_listen_t *this)
{
	listen_detail_t *data = this->data;

	free(data->filename);
	pairfree(&data->vps);

	if (data->fp != NULL) fclose(data->fp);
}


int detail_print(rad_listen_t *this, char *buffer, size_t bufsize)
{
	if (!this->server) {
		return snprintf(buffer, bufsize, "%s",
				((listen_detail_t *)(this->data))->filename);
	}

	return snprintf(buffer, bufsize, "detail file %s as server %s",
			((listen_detail_t *)(this->data))->filename,
			this->server);
}

int detail_encode(UNUSED rad_listen_t *this, UNUSED REQUEST *request)
{
	/*
	 *	We never encode responses "sent to" the detail file.
	 */
	return 0;
}

int detail_decode(UNUSED rad_listen_t *this, UNUSED REQUEST *request)
{
	/*
	 *	We never decode responses read from the detail file.
	 */
	return 0;
}


static const CONF_PARSER detail_config[] = {
	{ "filename",   PW_TYPE_STRING_PTR,
	  offsetof(listen_detail_t, filename), NULL,  NULL },
	{ "load_factor",   PW_TYPE_INTEGER,
	  offsetof(listen_detail_t, load_factor), NULL, Stringify(10)},

	{ NULL, -1, 0, NULL, NULL }		/* end the list */
};


/*
 *	Parse a detail section.
 */
int detail_parse(CONF_SECTION *cs, rad_listen_t *this)
{
	int		rcode;
	listen_detail_t *data;
	RADCLIENT	*client;

	if (!this->data) {
		this->data = rad_malloc(sizeof(listen_detail_t));
		memset(this->data, 0, sizeof(listen_detail_t));
	}

	data = this->data;

	rcode = cf_section_parse(cs, data, detail_config);
	if (rcode < 0) {
		cf_log_err(cf_sectiontoitem(cs), "Failed parsing listen section");
		return -1;
	}

	if (!data->filename) {
		cf_log_err(cf_sectiontoitem(cs), "No detail file specified in listen section");
		return -1;
	}

	if ((data->load_factor < 1) || (data->load_factor > 100)) {
		cf_log_err(cf_sectiontoitem(cs), "Load factor must be between 1 and 100");
		return -1;
	}

	data->vps = NULL;
	data->fp = NULL;
	data->state = STATE_UNOPENED;

	/*
	 *	Initialize the fake client.
	 */
	client = &data->detail_client;
	client->ipaddr.af = AF_INET;
	client->ipaddr.ipaddr.ip4addr.s_addr = INADDR_NONE;
	client->prefix = 0;
	client->longname = client->shortname = data->filename;
	client->secret = client->shortname;
	client->nastype = strdup("none");

	return 0;
}
