/*	$OpenBSD: connection.c,v 1.4 2010/09/25 16:20:06 sobrado Exp $ */

/*
 * Copyright (c) 2009 Claudio Jeker <claudio@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/uio.h>

#include <netinet/in.h>
#include <netinet/tcp.h>

#include <scsi/iscsi.h>
#include <scsi/scsi_all.h>
#include <dev/vscsivar.h>

#include <errno.h>
#include <event.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "iscsid.h"
#include "log.h"

void	conn_fsm(struct connection *, enum c_event);
void	conn_dispatch(int, short, void *);
void	conn_write_dispatch(int, short, void *);

int	c_do_connect(struct connection *, enum c_event);
int	c_do_login(struct connection *, enum c_event);
int	c_do_loggedin(struct connection *, enum c_event);
int	c_do_logout(struct connection *, enum c_event);

const char *conn_state(int);
const char *conn_event(enum c_event);

void
conn_new(struct session *s, struct connection_config *cc)
{
	struct connection *c;
	int nodelay = 1;

	if (!(c = calloc(1, sizeof(*c))))
		fatal("session_add_conn");

	c->fd = -1;
	c->state = CONN_FREE;
	c->session = s;
	c->cid = arc4random();
	c->config = *cc;
	TAILQ_INIT(&c->pdu_w);
	TAILQ_INIT(&c->tasks);
	TAILQ_INSERT_TAIL(&s->connections, c, entry);

	if (pdu_readbuf_set(&c->prbuf, PDU_READ_SIZE)) {
		log_warn("conn_new");
		conn_free(c);
		return;
	}

	/* create socket */
	c->fd = socket(c->config.TargetAddr.ss_family, SOCK_STREAM, 0);
	if (c->fd == -1) {
		log_warn("conn_new: socket");
		conn_free(c);
		return;
	}
	if (socket_setblockmode(c->fd, 1)) {
		log_warn("conn_new: socket_setblockmode");
		conn_free(c);
		return;
	}

	/* try to turn off TCP Nagle */
	if (setsockopt(c->fd, IPPROTO_TCP, TCP_NODELAY, &nodelay,
	    sizeof(nodelay)) == -1)
		log_warn("conn_new: setting TCP_NODELAY");



	event_set(&c->ev, c->fd, EV_READ|EV_PERSIST, conn_dispatch, c);
	event_set(&c->wev, c->fd, EV_WRITE, conn_write_dispatch, c);
	event_add(&c->ev, NULL);

	conn_fsm(c, CONN_EV_CONNECT);
}

void
conn_free(struct connection *c)
{
	pdu_readbuf_free(&c->prbuf);
	pdu_free_queue(&c->pdu_w);

	event_del(&c->ev);
	event_del(&c->wev);
	close(c->fd);

	TAILQ_REMOVE(&c->session->connections, c, entry);
	free(c);
}

void
conn_dispatch(int fd, short event, void *arg)
{
	struct connection *c = arg;
	ssize_t n;

	if (!(event & EV_READ)) {
		log_debug("spurious read call");
		return;
	}
	if ((n = pdu_read(c)) == -1) {
		conn_fail(c);
		return;
	}
	if (n == 0) {    /* connection closed */
		conn_fsm(c, CONN_EV_CLOSE);
		return;
	}

	pdu_parse(c);
}

void
conn_write_dispatch(int fd, short event, void *arg)
{
	struct connection *c = arg;
	ssize_t n;
	int error;
	socklen_t len;

	if (!(event & EV_WRITE)) {
		log_debug("spurious write call");
		return;
	}

	switch (c->state) {
	case CONN_XPT_WAIT:
		len = sizeof(error);
		if (getsockopt(c->fd, SOL_SOCKET, SO_ERROR,
		    &error, &len) == -1 || (errno = error)) {
			log_warn("cwd connect(%s)",
			    log_sockaddr(&c->config.TargetAddr));
			conn_fail(c);
			return;
		}
		conn_fsm(c, CONN_EV_CONNECTED);
		break;
	default:
		if ((n = pdu_write(c)) == -1) {
			conn_fail(c);
			return;
		}
		if (n == 0) {    /* connection closed */
			conn_fsm(c, CONN_EV_CLOSE);
			return;
		}

		/* check if there is more to send */
		if (pdu_pending(c))
			event_add(&c->wev, NULL);
	}
}

void
conn_close(struct connection *c)
{
	conn_fsm(c, CONN_EV_CLOSE);
}

void
conn_fail(struct connection *c)
{
	conn_fsm(c, CONN_EV_FAIL);
}

void
conn_loggedin(struct connection *c)
{
	if (c->session->config.SessionType == SESSION_TYPE_DISCOVERY)
		conn_fsm(c, CONN_EV_DISCOVERY);
	else
		conn_fsm(c, CONN_EV_LOGGED_IN);
}

int
conn_task_issue(struct connection *c, struct task *t)
{
	/* XXX need to verify that we're in the right state for the task */

	if (!TAILQ_EMPTY(&c->tasks))
		return 0;

	TAILQ_INSERT_TAIL(&c->tasks, t, entry);
	conn_task_schedule(c);
	return 1;
}

void
conn_task_schedule(struct connection *c)
{
	struct task *t = TAILQ_FIRST(&c->tasks);
	struct pdu *p, *np;

	if (!t) {
		log_debug("conn_task_schedule: task is hiding");
		return;
	}

	/* move pdus to the write queue */
	for (p = TAILQ_FIRST(&t->sendq); p != NULL; p = np) {
		np = TAILQ_NEXT(p, entry);
		TAILQ_REMOVE(&t->sendq, p, entry);
		conn_pdu_write(c, p);	/* maybe inline ? */
	}
}

void
conn_pdu_write(struct connection *c, struct pdu *p)
{
	struct iscsi_pdu *ipdu;

/* XXX I GUESS THIS SHOULD BE MOVED TO PDU SOMEHOW... */
	ipdu = pdu_getbuf(p, NULL, PDU_HEADER);
	switch (ISCSI_PDU_OPCODE(ipdu->opcode)) {
	case ISCSI_OP_TASK_REQUEST:
		ipdu->expstatsn = ntohl(c->expstatsn);
		break;
	}

	TAILQ_INSERT_TAIL(&c->pdu_w, p, entry);
	event_add(&c->wev, NULL);
}

/* connection state machine more or less as specified in the RFC */
struct {
	int		state;
	enum c_event	event;
	int		(*action)(struct connection *, enum c_event);
} fsm[] = {
	{ CONN_FREE, CONN_EV_CONNECT, c_do_connect },
	{ CONN_XPT_WAIT, CONN_EV_CONNECTED, c_do_login },
	{ CONN_IN_LOGIN, CONN_EV_LOGGED_IN, c_do_loggedin },
	{ CONN_IN_LOGIN, CONN_EV_DISCOVERY, c_do_loggedin },
	{ CONN_LOGGED_IN, CONN_EV_CLOSE, c_do_logout },
	{ 0, 0, NULL }
};

void
conn_fsm(struct connection *c, enum c_event event)
{
	int	i, ns;

	for (i = 0; fsm[i].action != NULL; i++) {
		if (c->state & fsm[i].state && event == fsm[i].event) {
			ns = fsm[i].action(c, event);
			log_debug("conn_fsm: %s ev %s -> %s",
			   conn_state(c->state), conn_event(event),
			   conn_state(ns));
			if (ns == -1)
				/* XXX better please */
				fatalx("conn_fsm: action failed");
			c->state = ns;
			return;
		}
	}
	log_warnx("conn_fsm: unhandled state transition [%s, %s]",
		conn_state(c->state), conn_event(event));
	fatalx("bork bork bork");
}

int
c_do_connect(struct connection *c, enum c_event ev)
{
	if (c->fd == -1)
		fatalx("c_do_connect, lost socket");

	if (connect(c->fd, (struct sockaddr *)&c->config.TargetAddr,
	    c->config.TargetAddr.ss_len) == -1) {
		if (errno == EINPROGRESS) {
			event_add(&c->wev, NULL);
			return (CONN_XPT_WAIT);
		} else {
			log_warn("connect(%s)",
			    log_sockaddr(&c->config.TargetAddr));
			return (-1);
		}
	}
	/* move forward */
	return (c_do_login(c, CONN_EV_CONNECTED));
}

int
c_do_login(struct connection *c, enum c_event ev)
{
	/* start a login session and hope for the best ... */
	initiator_login(c);
	return (CONN_IN_LOGIN);
}

int
c_do_loggedin(struct connection *c, enum c_event ev)
{
	if (ev == CONN_EV_LOGGED_IN)
		vscsi_event(VSCSI_REQPROBE, c->session->target, 0);
	else
		initiator_discovery(c->session);
	return (CONN_LOGGED_IN);
}

int
c_do_logout(struct connection *c, enum c_event ev)
{
	/* do full logout */
	return (CONN_FREE);
}

const char *
conn_state(int s)
{
	static char buf[15];

	switch (s) {
	case CONN_FREE:
		return "FREE";
	case CONN_XPT_WAIT:
		return "XPT_WAIT";
	case CONN_XPT_UP:
		return "XPT_UP";
	case CONN_IN_LOGIN:
		return "IN_LOGIN";
	case CONN_LOGGED_IN:
		return "LOGGED_IN";
	case CONN_IN_LOGOUT:
		return "IN_LOGOUT";
	case CONN_LOGOUT_REQ:
		return "LOGOUT_REQ";
	case CONN_CLEANUP_WAIT:
		return "CLEANUP_WAIT";
	case CONN_IN_CLEANUP:
		return "IN_CLEANUP";
	default:
		snprintf(buf, sizeof(buf), "UKNWN %x", s);
		return buf;
	}
	/* NOTREACHED */
}

const char *
conn_event(enum c_event e)
{
	static char buf[15];

	switch (e) {
	case CONN_EV_FAIL:
		return "fail";
	case CONN_EV_CONNECT:
		return "connect";
	case CONN_EV_CONNECTED:
		return "connected";
	case CONN_EV_LOGGED_IN:
		return "logged in";
	case CONN_EV_DISCOVERY:
		return "discovery";
	case CONN_EV_CLOSE:
		return "close";
	}

	snprintf(buf, sizeof(buf), "UKNWN %d", e);
	return buf;
}