xref: /freebsd-10.3-release/sys/rpc/svc.c

/*	$NetBSD: svc.c,v 1.21 2000/07/06 03:10:35 christos Exp $	*/

/*-
 * Copyright (c) 2009, Sun Microsystems, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of Sun Microsystems, Inc. nor the names of its
 *   contributors may be used to endorse or promote products derived
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char *sccsid2 = "@(#)svc.c 1.44 88/02/08 Copyr 1984 Sun Micro";
static char *sccsid = "@(#)svc.c	2.4 88/08/11 4.0 RPCSRC";
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: stable/10/sys/rpc/svc.c 267740 2014-06-22 18:01:40Z mav $");

/*
 * svc.c, Server-side remote procedure call interface.
 *
 * There are two sets of procedures here.  The xprt routines are
 * for handling transport handles.  The svc routines handle the
 * list of service routines.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 */

#include <sys/param.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/sx.h>
#include <sys/ucred.h>

#include <rpc/rpc.h>
#include <rpc/rpcb_clnt.h>
#include <rpc/replay.h>

#include <rpc/rpc_com.h>

#define SVC_VERSQUIET 0x0001		/* keep quiet about vers mismatch */
#define version_keepquiet(xp) (SVC_EXT(xp)->xp_flags & SVC_VERSQUIET)

static struct svc_callout *svc_find(SVCPOOL *pool, rpcprog_t, rpcvers_t,
    char *);
static void svc_new_thread(SVCPOOL *pool);
static void xprt_unregister_locked(SVCXPRT *xprt);
static void svc_change_space_used(SVCPOOL *pool, int delta);
static bool_t svc_request_space_available(SVCPOOL *pool);

/* ***************  SVCXPRT related stuff **************** */

static int svcpool_minthread_sysctl(SYSCTL_HANDLER_ARGS);
static int svcpool_maxthread_sysctl(SYSCTL_HANDLER_ARGS);

SVCPOOL*
svcpool_create(const char *name, struct sysctl_oid_list *sysctl_base)
{
	SVCPOOL *pool;

	pool = malloc(sizeof(SVCPOOL), M_RPC, M_WAITOK|M_ZERO);

	mtx_init(&pool->sp_lock, "sp_lock", NULL, MTX_DEF);
	pool->sp_name = name;
	pool->sp_state = SVCPOOL_INIT;
	pool->sp_proc = NULL;
	TAILQ_INIT(&pool->sp_xlist);
	TAILQ_INIT(&pool->sp_active);
	TAILQ_INIT(&pool->sp_callouts);
	TAILQ_INIT(&pool->sp_lcallouts);
	LIST_INIT(&pool->sp_threads);
	LIST_INIT(&pool->sp_idlethreads);
	pool->sp_minthreads = 1;
	pool->sp_maxthreads = 1;
	pool->sp_threadcount = 0;

	/*
	 * Don't use more than a quarter of mbuf clusters or more than
	 * 45Mb buffering requests.
	 */
	pool->sp_space_high = nmbclusters * MCLBYTES / 4;
	if (pool->sp_space_high > 45 << 20)
		pool->sp_space_high = 45 << 20;
	pool->sp_space_low = 2 * pool->sp_space_high / 3;

	sysctl_ctx_init(&pool->sp_sysctl);
	if (sysctl_base) {
		SYSCTL_ADD_PROC(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "minthreads", CTLTYPE_INT | CTLFLAG_RW,
		    pool, 0, svcpool_minthread_sysctl, "I", "");
		SYSCTL_ADD_PROC(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "maxthreads", CTLTYPE_INT | CTLFLAG_RW,
		    pool, 0, svcpool_maxthread_sysctl, "I", "");
		SYSCTL_ADD_INT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "threads", CTLFLAG_RD, &pool->sp_threadcount, 0, "");

		SYSCTL_ADD_UINT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "request_space_used", CTLFLAG_RD,
		    &pool->sp_space_used, 0,
		    "Space in parsed but not handled requests.");

		SYSCTL_ADD_UINT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "request_space_used_highest", CTLFLAG_RD,
		    &pool->sp_space_used_highest, 0,
		    "Highest space used since reboot.");

		SYSCTL_ADD_UINT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "request_space_high", CTLFLAG_RW,
		    &pool->sp_space_high, 0,
		    "Maximum space in parsed but not handled requests.");

		SYSCTL_ADD_UINT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "request_space_low", CTLFLAG_RW,
		    &pool->sp_space_low, 0,
		    "Low water mark for request space.");

		SYSCTL_ADD_INT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "request_space_throttled", CTLFLAG_RD,
		    &pool->sp_space_throttled, 0,
		    "Whether nfs requests are currently throttled");

		SYSCTL_ADD_INT(&pool->sp_sysctl, sysctl_base, OID_AUTO,
		    "request_space_throttle_count", CTLFLAG_RD,
		    &pool->sp_space_throttle_count, 0,
		    "Count of times throttling based on request space has occurred");
	}

	return pool;
}

void
svcpool_destroy(SVCPOOL *pool)
{
	SVCXPRT *xprt, *nxprt;
	struct svc_callout *s;
	struct svc_loss_callout *sl;
	struct svcxprt_list cleanup;

	TAILQ_INIT(&cleanup);
	mtx_lock(&pool->sp_lock);

	while (TAILQ_FIRST(&pool->sp_xlist)) {
		xprt = TAILQ_FIRST(&pool->sp_xlist);
		xprt_unregister_locked(xprt);
		TAILQ_INSERT_TAIL(&cleanup, xprt, xp_link);
	}

	while ((s = TAILQ_FIRST(&pool->sp_callouts)) != NULL) {
		mtx_unlock(&pool->sp_lock);
		svc_unreg(pool, s->sc_prog, s->sc_vers);
		mtx_lock(&pool->sp_lock);
	}
	while ((sl = TAILQ_FIRST(&pool->sp_lcallouts)) != NULL) {
		mtx_unlock(&pool->sp_lock);
		svc_loss_unreg(pool, sl->slc_dispatch);
		mtx_lock(&pool->sp_lock);
	}
	mtx_unlock(&pool->sp_lock);

	TAILQ_FOREACH_SAFE(xprt, &cleanup, xp_link, nxprt) {
		SVC_RELEASE(xprt);
	}

	mtx_destroy(&pool->sp_lock);

	if (pool->sp_rcache)
		replay_freecache(pool->sp_rcache);

	sysctl_ctx_free(&pool->sp_sysctl);
	free(pool, M_RPC);
}

static bool_t
svcpool_active(SVCPOOL *pool)
{
	enum svcpool_state state = pool->sp_state;

	if (state == SVCPOOL_INIT || state == SVCPOOL_CLOSING)
		return (FALSE);
	return (TRUE);
}

/*
 * Sysctl handler to set the minimum thread count on a pool
 */
static int
svcpool_minthread_sysctl(SYSCTL_HANDLER_ARGS)
{
	SVCPOOL *pool;
	int newminthreads, error, n;

	pool = oidp->oid_arg1;
	newminthreads = pool->sp_minthreads;
	error = sysctl_handle_int(oidp, &newminthreads, 0, req);
	if (error == 0 && newminthreads != pool->sp_minthreads) {
		if (newminthreads > pool->sp_maxthreads)
			return (EINVAL);
		mtx_lock(&pool->sp_lock);
		if (newminthreads > pool->sp_minthreads
		    && svcpool_active(pool)) {
			/*
			 * If the pool is running and we are
			 * increasing, create some more threads now.
			 */
			n = newminthreads - pool->sp_threadcount;
			if (n > 0) {
				mtx_unlock(&pool->sp_lock);
				while (n--)
					svc_new_thread(pool);
				mtx_lock(&pool->sp_lock);
			}
		}
		pool->sp_minthreads = newminthreads;
		mtx_unlock(&pool->sp_lock);
	}
	return (error);
}

/*
 * Sysctl handler to set the maximum thread count on a pool
 */
static int
svcpool_maxthread_sysctl(SYSCTL_HANDLER_ARGS)
{
	SVCPOOL *pool;
	SVCTHREAD *st;
	int newmaxthreads, error;

	pool = oidp->oid_arg1;
	newmaxthreads = pool->sp_maxthreads;
	error = sysctl_handle_int(oidp, &newmaxthreads, 0, req);
	if (error == 0 && newmaxthreads != pool->sp_maxthreads) {
		if (newmaxthreads < pool->sp_minthreads)
			return (EINVAL);
		mtx_lock(&pool->sp_lock);
		if (newmaxthreads < pool->sp_maxthreads
		    && svcpool_active(pool)) {
			/*
			 * If the pool is running and we are
			 * decreasing, wake up some idle threads to
			 * encourage them to exit.
			 */
			LIST_FOREACH(st, &pool->sp_idlethreads, st_ilink)
				cv_signal(&st->st_cond);
		}
		pool->sp_maxthreads = newmaxthreads;
		mtx_unlock(&pool->sp_lock);
	}
	return (error);
}

/*
 * Activate a transport handle.
 */
void
xprt_register(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;

	SVC_ACQUIRE(xprt);
	mtx_lock(&pool->sp_lock);
	xprt->xp_registered = TRUE;
	xprt->xp_active = FALSE;
	TAILQ_INSERT_TAIL(&pool->sp_xlist, xprt, xp_link);
	mtx_unlock(&pool->sp_lock);
}

/*
 * De-activate a transport handle. Note: the locked version doesn't
 * release the transport - caller must do that after dropping the pool
 * lock.
 */
static void
xprt_unregister_locked(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;

	mtx_assert(&pool->sp_lock, MA_OWNED);
	KASSERT(xprt->xp_registered == TRUE,
	    ("xprt_unregister_locked: not registered"));
	xprt_inactive_locked(xprt);
	TAILQ_REMOVE(&pool->sp_xlist, xprt, xp_link);
	xprt->xp_registered = FALSE;
}

void
xprt_unregister(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;

	mtx_lock(&pool->sp_lock);
	if (xprt->xp_registered == FALSE) {
		/* Already unregistered by another thread */
		mtx_unlock(&pool->sp_lock);
		return;
	}
	xprt_unregister_locked(xprt);
	mtx_unlock(&pool->sp_lock);

	SVC_RELEASE(xprt);
}

/*
 * Attempt to assign a service thread to this transport.
 */
static int
xprt_assignthread(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;
	SVCTHREAD *st;

	mtx_assert(&pool->sp_lock, MA_OWNED);
	st = LIST_FIRST(&pool->sp_idlethreads);
	if (st) {
		LIST_REMOVE(st, st_ilink);
		st->st_idle = FALSE;
		SVC_ACQUIRE(xprt);
		xprt->xp_thread = st;
		st->st_xprt = xprt;
		cv_signal(&st->st_cond);
		return (TRUE);
	} else {
		/*
		 * See if we can create a new thread. The
		 * actual thread creation happens in
		 * svc_run_internal because our locking state
		 * is poorly defined (we are typically called
		 * from a socket upcall). Don't create more
		 * than one thread per second.
		 */
		if (pool->sp_state == SVCPOOL_ACTIVE
		    && pool->sp_lastcreatetime < time_uptime
		    && pool->sp_threadcount < pool->sp_maxthreads) {
			pool->sp_state = SVCPOOL_THREADWANTED;
		}
	}
	return (FALSE);
}

void
xprt_active(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;

	mtx_lock(&pool->sp_lock);

	if (!xprt->xp_registered) {
		/*
		 * Race with xprt_unregister - we lose.
		 */
		mtx_unlock(&pool->sp_lock);
		return;
	}

	if (!xprt->xp_active) {
		xprt->xp_active = TRUE;
		if (xprt->xp_thread == NULL) {
			if (!svc_request_space_available(pool) ||
			    !xprt_assignthread(xprt))
				TAILQ_INSERT_TAIL(&pool->sp_active, xprt,
				    xp_alink);
		}
	}

	mtx_unlock(&pool->sp_lock);
}

void
xprt_inactive_locked(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;

	mtx_assert(&pool->sp_lock, MA_OWNED);
	if (xprt->xp_active) {
		if (xprt->xp_thread == NULL)
			TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
		xprt->xp_active = FALSE;
	}
}

void
xprt_inactive(SVCXPRT *xprt)
{
	SVCPOOL *pool = xprt->xp_pool;

	mtx_lock(&pool->sp_lock);
	xprt_inactive_locked(xprt);
	mtx_unlock(&pool->sp_lock);
}

/*
 * Variant of xprt_inactive() for use only when sure that port is
 * assigned to thread. For example, withing receive handlers.
 */
void
xprt_inactive_self(SVCXPRT *xprt)
{

	KASSERT(xprt->xp_thread != NULL,
	    ("xprt_inactive_self(%p) with NULL xp_thread", xprt));
	xprt->xp_active = FALSE;
}

/*
 * Add a service program to the callout list.
 * The dispatch routine will be called when a rpc request for this
 * program number comes in.
 */
bool_t
svc_reg(SVCXPRT *xprt, const rpcprog_t prog, const rpcvers_t vers,
    void (*dispatch)(struct svc_req *, SVCXPRT *),
    const struct netconfig *nconf)
{
	SVCPOOL *pool = xprt->xp_pool;
	struct svc_callout *s;
	char *netid = NULL;
	int flag = 0;

/* VARIABLES PROTECTED BY svc_lock: s, svc_head */

	if (xprt->xp_netid) {
		netid = strdup(xprt->xp_netid, M_RPC);
		flag = 1;
	} else if (nconf && nconf->nc_netid) {
		netid = strdup(nconf->nc_netid, M_RPC);
		flag = 1;
	} /* must have been created with svc_raw_create */
	if ((netid == NULL) && (flag == 1)) {
		return (FALSE);
	}

	mtx_lock(&pool->sp_lock);
	if ((s = svc_find(pool, prog, vers, netid)) != NULL) {
		if (netid)
			free(netid, M_RPC);
		if (s->sc_dispatch == dispatch)
			goto rpcb_it; /* he is registering another xptr */
		mtx_unlock(&pool->sp_lock);
		return (FALSE);
	}
	s = malloc(sizeof (struct svc_callout), M_RPC, M_NOWAIT);
	if (s == NULL) {
		if (netid)
			free(netid, M_RPC);
		mtx_unlock(&pool->sp_lock);
		return (FALSE);
	}

	s->sc_prog = prog;
	s->sc_vers = vers;
	s->sc_dispatch = dispatch;
	s->sc_netid = netid;
	TAILQ_INSERT_TAIL(&pool->sp_callouts, s, sc_link);

	if ((xprt->xp_netid == NULL) && (flag == 1) && netid)
		((SVCXPRT *) xprt)->xp_netid = strdup(netid, M_RPC);

rpcb_it:
	mtx_unlock(&pool->sp_lock);
	/* now register the information with the local binder service */
	if (nconf) {
		bool_t dummy;
		struct netconfig tnc;
		struct netbuf nb;
		tnc = *nconf;
		nb.buf = &xprt->xp_ltaddr;
		nb.len = xprt->xp_ltaddr.ss_len;
		dummy = rpcb_set(prog, vers, &tnc, &nb);
		return (dummy);
	}
	return (TRUE);
}

/*
 * Remove a service program from the callout list.
 */
void
svc_unreg(SVCPOOL *pool, const rpcprog_t prog, const rpcvers_t vers)
{
	struct svc_callout *s;

	/* unregister the information anyway */
	(void) rpcb_unset(prog, vers, NULL);
	mtx_lock(&pool->sp_lock);
	while ((s = svc_find(pool, prog, vers, NULL)) != NULL) {
		TAILQ_REMOVE(&pool->sp_callouts, s, sc_link);
		if (s->sc_netid)
			mem_free(s->sc_netid, sizeof (s->sc_netid) + 1);
		mem_free(s, sizeof (struct svc_callout));
	}
	mtx_unlock(&pool->sp_lock);
}

/*
 * Add a service connection loss program to the callout list.
 * The dispatch routine will be called when some port in ths pool die.
 */
bool_t
svc_loss_reg(SVCXPRT *xprt, void (*dispatch)(SVCXPRT *))
{
	SVCPOOL *pool = xprt->xp_pool;
	struct svc_loss_callout *s;

	mtx_lock(&pool->sp_lock);
	TAILQ_FOREACH(s, &pool->sp_lcallouts, slc_link) {
		if (s->slc_dispatch == dispatch)
			break;
	}
	if (s != NULL) {
		mtx_unlock(&pool->sp_lock);
		return (TRUE);
	}
	s = malloc(sizeof (struct svc_callout), M_RPC, M_NOWAIT);
	if (s == NULL) {
		mtx_unlock(&pool->sp_lock);
		return (FALSE);
	}
	s->slc_dispatch = dispatch;
	TAILQ_INSERT_TAIL(&pool->sp_lcallouts, s, slc_link);
	mtx_unlock(&pool->sp_lock);
	return (TRUE);
}

/*
 * Remove a service connection loss program from the callout list.
 */
void
svc_loss_unreg(SVCPOOL *pool, void (*dispatch)(SVCXPRT *))
{
	struct svc_loss_callout *s;

	mtx_lock(&pool->sp_lock);
	TAILQ_FOREACH(s, &pool->sp_lcallouts, slc_link) {
		if (s->slc_dispatch == dispatch) {
			TAILQ_REMOVE(&pool->sp_lcallouts, s, slc_link);
			free(s, M_RPC);
			break;
		}
	}
	mtx_unlock(&pool->sp_lock);
}

/* ********************** CALLOUT list related stuff ************* */

/*
 * Search the callout list for a program number, return the callout
 * struct.
 */
static struct svc_callout *
svc_find(SVCPOOL *pool, rpcprog_t prog, rpcvers_t vers, char *netid)
{
	struct svc_callout *s;

	mtx_assert(&pool->sp_lock, MA_OWNED);
	TAILQ_FOREACH(s, &pool->sp_callouts, sc_link) {
		if (s->sc_prog == prog && s->sc_vers == vers
		    && (netid == NULL || s->sc_netid == NULL ||
			strcmp(netid, s->sc_netid) == 0))
			break;
	}

	return (s);
}

/* ******************* REPLY GENERATION ROUTINES  ************ */

static bool_t
svc_sendreply_common(struct svc_req *rqstp, struct rpc_msg *rply,
    struct mbuf *body)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	bool_t ok;

	if (rqstp->rq_args) {
		m_freem(rqstp->rq_args);
		rqstp->rq_args = NULL;
	}

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    rply, svc_getrpccaller(rqstp), body);

	if (!SVCAUTH_WRAP(&rqstp->rq_auth, &body))
		return (FALSE);

	ok = SVC_REPLY(xprt, rply, rqstp->rq_addr, body, &rqstp->rq_reply_seq);
	if (rqstp->rq_addr) {
		free(rqstp->rq_addr, M_SONAME);
		rqstp->rq_addr = NULL;
	}

	return (ok);
}

/*
 * Send a reply to an rpc request
 */
bool_t
svc_sendreply(struct svc_req *rqstp, xdrproc_t xdr_results, void * xdr_location)
{
	struct rpc_msg rply;
	struct mbuf *m;
	XDR xdrs;
	bool_t ok;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = SUCCESS;
	rply.acpted_rply.ar_results.where = NULL;
	rply.acpted_rply.ar_results.proc = (xdrproc_t) xdr_void;

	m = m_getcl(M_WAITOK, MT_DATA, 0);
	xdrmbuf_create(&xdrs, m, XDR_ENCODE);
	ok = xdr_results(&xdrs, xdr_location);
	XDR_DESTROY(&xdrs);

	if (ok) {
		return (svc_sendreply_common(rqstp, &rply, m));
	} else {
		m_freem(m);
		return (FALSE);
	}
}

bool_t
svc_sendreply_mbuf(struct svc_req *rqstp, struct mbuf *m)
{
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = SUCCESS;
	rply.acpted_rply.ar_results.where = NULL;
	rply.acpted_rply.ar_results.proc = (xdrproc_t) xdr_void;

	return (svc_sendreply_common(rqstp, &rply, m));
}

/*
 * No procedure error reply
 */
void
svcerr_noproc(struct svc_req *rqstp)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = PROC_UNAVAIL;

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    &rply, svc_getrpccaller(rqstp), NULL);

	svc_sendreply_common(rqstp, &rply, NULL);
}

/*
 * Can't decode args error reply
 */
void
svcerr_decode(struct svc_req *rqstp)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = GARBAGE_ARGS;

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    &rply, (struct sockaddr *) &xprt->xp_rtaddr, NULL);

	svc_sendreply_common(rqstp, &rply, NULL);
}

/*
 * Some system error
 */
void
svcerr_systemerr(struct svc_req *rqstp)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = SYSTEM_ERR;

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    &rply, svc_getrpccaller(rqstp), NULL);

	svc_sendreply_common(rqstp, &rply, NULL);
}

/*
 * Authentication error reply
 */
void
svcerr_auth(struct svc_req *rqstp, enum auth_stat why)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_DENIED;
	rply.rjcted_rply.rj_stat = AUTH_ERROR;
	rply.rjcted_rply.rj_why = why;

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    &rply, svc_getrpccaller(rqstp), NULL);

	svc_sendreply_common(rqstp, &rply, NULL);
}

/*
 * Auth too weak error reply
 */
void
svcerr_weakauth(struct svc_req *rqstp)
{

	svcerr_auth(rqstp, AUTH_TOOWEAK);
}

/*
 * Program unavailable error reply
 */
void
svcerr_noprog(struct svc_req *rqstp)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = PROG_UNAVAIL;

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    &rply, svc_getrpccaller(rqstp), NULL);

	svc_sendreply_common(rqstp, &rply, NULL);
}

/*
 * Program version mismatch error reply
 */
void
svcerr_progvers(struct svc_req *rqstp, rpcvers_t low_vers, rpcvers_t high_vers)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	struct rpc_msg rply;

	rply.rm_xid = rqstp->rq_xid;
	rply.rm_direction = REPLY;
	rply.rm_reply.rp_stat = MSG_ACCEPTED;
	rply.acpted_rply.ar_verf = rqstp->rq_verf;
	rply.acpted_rply.ar_stat = PROG_MISMATCH;
	rply.acpted_rply.ar_vers.low = (uint32_t)low_vers;
	rply.acpted_rply.ar_vers.high = (uint32_t)high_vers;

	if (xprt->xp_pool->sp_rcache)
		replay_setreply(xprt->xp_pool->sp_rcache,
		    &rply, svc_getrpccaller(rqstp), NULL);

	svc_sendreply_common(rqstp, &rply, NULL);
}

/*
 * Allocate a new server transport structure. All fields are
 * initialized to zero and xp_p3 is initialized to point at an
 * extension structure to hold various flags and authentication
 * parameters.
 */
SVCXPRT *
svc_xprt_alloc()
{
	SVCXPRT *xprt;
	SVCXPRT_EXT *ext;

	xprt = mem_alloc(sizeof(SVCXPRT));
	memset(xprt, 0, sizeof(SVCXPRT));
	ext = mem_alloc(sizeof(SVCXPRT_EXT));
	memset(ext, 0, sizeof(SVCXPRT_EXT));
	xprt->xp_p3 = ext;
	refcount_init(&xprt->xp_refs, 1);

	return (xprt);
}

/*
 * Free a server transport structure.
 */
void
svc_xprt_free(xprt)
	SVCXPRT *xprt;
{

	mem_free(xprt->xp_p3, sizeof(SVCXPRT_EXT));
	mem_free(xprt, sizeof(SVCXPRT));
}

/* ******************* SERVER INPUT STUFF ******************* */

/*
 * Read RPC requests from a transport and queue them to be
 * executed. We handle authentication and replay cache replies here.
 * Actually dispatching the RPC is deferred till svc_executereq.
 */
static enum xprt_stat
svc_getreq(SVCXPRT *xprt, struct svc_req **rqstp_ret)
{
	SVCPOOL *pool = xprt->xp_pool;
	struct svc_req *r;
	struct rpc_msg msg;
	struct mbuf *args;
	struct svc_loss_callout *s;
	enum xprt_stat stat;

	/* now receive msgs from xprtprt (support batch calls) */
	r = malloc(sizeof(*r), M_RPC, M_WAITOK|M_ZERO);

	msg.rm_call.cb_cred.oa_base = r->rq_credarea;
	msg.rm_call.cb_verf.oa_base = &r->rq_credarea[MAX_AUTH_BYTES];
	r->rq_clntcred = &r->rq_credarea[2*MAX_AUTH_BYTES];
	if (SVC_RECV(xprt, &msg, &r->rq_addr, &args)) {
		enum auth_stat why;

		/*
		 * Handle replays and authenticate before queuing the
		 * request to be executed.
		 */
		SVC_ACQUIRE(xprt);
		r->rq_xprt = xprt;
		if (pool->sp_rcache) {
			struct rpc_msg repmsg;
			struct mbuf *repbody;
			enum replay_state rs;
			rs = replay_find(pool->sp_rcache, &msg,
			    svc_getrpccaller(r), &repmsg, &repbody);
			switch (rs) {
			case RS_NEW:
				break;
			case RS_DONE:
				SVC_REPLY(xprt, &repmsg, r->rq_addr,
				    repbody, &r->rq_reply_seq);
				if (r->rq_addr) {
					free(r->rq_addr, M_SONAME);
					r->rq_addr = NULL;
				}
				m_freem(args);
				goto call_done;

			default:
				m_freem(args);
				goto call_done;
			}
		}

		r->rq_xid = msg.rm_xid;
		r->rq_prog = msg.rm_call.cb_prog;
		r->rq_vers = msg.rm_call.cb_vers;
		r->rq_proc = msg.rm_call.cb_proc;
		r->rq_size = sizeof(*r) + m_length(args, NULL);
		r->rq_args = args;
		if ((why = _authenticate(r, &msg)) != AUTH_OK) {
			/*
			 * RPCSEC_GSS uses this return code
			 * for requests that form part of its
			 * context establishment protocol and
			 * should not be dispatched to the
			 * application.
			 */
			if (why != RPCSEC_GSS_NODISPATCH)
				svcerr_auth(r, why);
			goto call_done;
		}

		if (!SVCAUTH_UNWRAP(&r->rq_auth, &r->rq_args)) {
			svcerr_decode(r);
			goto call_done;
		}

		/*
		 * Everything checks out, return request to caller.
		 */
		*rqstp_ret = r;
		r = NULL;
	}
call_done:
	if (r) {
		svc_freereq(r);
		r = NULL;
	}
	if ((stat = SVC_STAT(xprt)) == XPRT_DIED) {
		TAILQ_FOREACH(s, &pool->sp_lcallouts, slc_link)
			(*s->slc_dispatch)(xprt);
		xprt_unregister(xprt);
	}

	return (stat);
}

static void
svc_executereq(struct svc_req *rqstp)
{
	SVCXPRT *xprt = rqstp->rq_xprt;
	SVCPOOL *pool = xprt->xp_pool;
	int prog_found;
	rpcvers_t low_vers;
	rpcvers_t high_vers;
	struct svc_callout *s;

	/* now match message with a registered service*/
	prog_found = FALSE;
	low_vers = (rpcvers_t) -1L;
	high_vers = (rpcvers_t) 0L;
	TAILQ_FOREACH(s, &pool->sp_callouts, sc_link) {
		if (s->sc_prog == rqstp->rq_prog) {
			if (s->sc_vers == rqstp->rq_vers) {
				/*
				 * We hand ownership of r to the
				 * dispatch method - they must call
				 * svc_freereq.
				 */
				(*s->sc_dispatch)(rqstp, xprt);
				return;
			}  /* found correct version */
			prog_found = TRUE;
			if (s->sc_vers < low_vers)
				low_vers = s->sc_vers;
			if (s->sc_vers > high_vers)
				high_vers = s->sc_vers;
		}   /* found correct program */
	}

	/*
	 * if we got here, the program or version
	 * is not served ...
	 */
	if (prog_found)
		svcerr_progvers(rqstp, low_vers, high_vers);
	else
		svcerr_noprog(rqstp);

	svc_freereq(rqstp);
}

static void
svc_checkidle(SVCPOOL *pool)
{
	SVCXPRT *xprt, *nxprt;
	time_t timo;
	struct svcxprt_list cleanup;

	TAILQ_INIT(&cleanup);
	TAILQ_FOREACH_SAFE(xprt, &pool->sp_xlist, xp_link, nxprt) {
		/*
		 * Only some transports have idle timers. Don't time
		 * something out which is just waking up.
		 */
		if (!xprt->xp_idletimeout || xprt->xp_thread)
			continue;

		timo = xprt->xp_lastactive + xprt->xp_idletimeout;
		if (time_uptime > timo) {
			xprt_unregister_locked(xprt);
			TAILQ_INSERT_TAIL(&cleanup, xprt, xp_link);
		}
	}

	mtx_unlock(&pool->sp_lock);
	TAILQ_FOREACH_SAFE(xprt, &cleanup, xp_link, nxprt) {
		SVC_RELEASE(xprt);
	}
	mtx_lock(&pool->sp_lock);

}

static void
svc_assign_waiting_sockets(SVCPOOL *pool)
{
	SVCXPRT *xprt;

	mtx_lock(&pool->sp_lock);
	while ((xprt = TAILQ_FIRST(&pool->sp_active)) != NULL) {
		if (xprt_assignthread(xprt))
			TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
		else
			break;
	}
	mtx_unlock(&pool->sp_lock);
}

static void
svc_change_space_used(SVCPOOL *pool, int delta)
{
	unsigned int value;

	value = atomic_fetchadd_int(&pool->sp_space_used, delta) + delta;
	if (delta > 0) {
		if (value >= pool->sp_space_high && !pool->sp_space_throttled) {
			pool->sp_space_throttled = TRUE;
			pool->sp_space_throttle_count++;
		}
		if (value > pool->sp_space_used_highest)
			pool->sp_space_used_highest = value;
	} else {
		if (value < pool->sp_space_low && pool->sp_space_throttled) {
			pool->sp_space_throttled = FALSE;
			svc_assign_waiting_sockets(pool);
		}
	}
}

static bool_t
svc_request_space_available(SVCPOOL *pool)
{

	if (pool->sp_space_throttled)
		return (FALSE);
	return (TRUE);
}

static void
svc_run_internal(SVCPOOL *pool, bool_t ismaster)
{
	SVCTHREAD *st, *stpref;
	SVCXPRT *xprt;
	enum xprt_stat stat;
	struct svc_req *rqstp;
	size_t sz;
	int error;

	st = mem_alloc(sizeof(*st));
	mtx_init(&st->st_lock, "st_lock", NULL, MTX_DEF);
	st->st_pool = pool;
	st->st_xprt = NULL;
	STAILQ_INIT(&st->st_reqs);
	cv_init(&st->st_cond, "rpcsvc");

	mtx_lock(&pool->sp_lock);
	LIST_INSERT_HEAD(&pool->sp_threads, st, st_link);

	/*
	 * If we are a new thread which was spawned to cope with
	 * increased load, set the state back to SVCPOOL_ACTIVE.
	 */
	if (pool->sp_state == SVCPOOL_THREADSTARTING)
		pool->sp_state = SVCPOOL_ACTIVE;

	while (pool->sp_state != SVCPOOL_CLOSING) {
		/*
		 * Create new thread if requested.
		 */
		if (pool->sp_state == SVCPOOL_THREADWANTED) {
			pool->sp_state = SVCPOOL_THREADSTARTING;
			pool->sp_lastcreatetime = time_uptime;
			mtx_unlock(&pool->sp_lock);
			svc_new_thread(pool);
			mtx_lock(&pool->sp_lock);
			continue;
		}

		/*
		 * Check for idle transports once per second.
		 */
		if (time_uptime > pool->sp_lastidlecheck) {
			pool->sp_lastidlecheck = time_uptime;
			svc_checkidle(pool);
		}

		xprt = st->st_xprt;
		if (!xprt) {
			/*
			 * Enforce maxthreads count.
			 */
			if (pool->sp_threadcount > pool->sp_maxthreads)
				break;

			/*
			 * Before sleeping, see if we can find an
			 * active transport which isn't being serviced
			 * by a thread.
			 */
			if (svc_request_space_available(pool) &&
			    (xprt = TAILQ_FIRST(&pool->sp_active)) != NULL) {
				TAILQ_REMOVE(&pool->sp_active, xprt, xp_alink);
				SVC_ACQUIRE(xprt);
				xprt->xp_thread = st;
				st->st_xprt = xprt;
				continue;
			}

			LIST_INSERT_HEAD(&pool->sp_idlethreads, st, st_ilink);
			st->st_idle = TRUE;
			if (ismaster || (!ismaster &&
			    pool->sp_threadcount > pool->sp_minthreads))
				error = cv_timedwait_sig(&st->st_cond,
				    &pool->sp_lock, 5 * hz);
			else
				error = cv_wait_sig(&st->st_cond,
				    &pool->sp_lock);
			if (st->st_idle) {
				LIST_REMOVE(st, st_ilink);
				st->st_idle = FALSE;
			}

			/*
			 * Reduce worker thread count when idle.
			 */
			if (error == EWOULDBLOCK) {
				if (!ismaster
				    && (pool->sp_threadcount
					> pool->sp_minthreads)
					&& !st->st_xprt)
					break;
			} else if (error) {
				mtx_unlock(&pool->sp_lock);
				svc_exit(pool);
				mtx_lock(&pool->sp_lock);
				break;
			}
			continue;
		}
		mtx_unlock(&pool->sp_lock);

		/*
		 * Drain the transport socket and queue up any RPCs.
		 */
		xprt->xp_lastactive = time_uptime;
		do {
			if (!svc_request_space_available(pool))
				break;
			rqstp = NULL;
			stat = svc_getreq(xprt, &rqstp);
			if (rqstp) {
				svc_change_space_used(pool, rqstp->rq_size);
				/*
				 * See if the application has a preference
				 * for some other thread.
				 */
				if (pool->sp_assign) {
					stpref = pool->sp_assign(st, rqstp);
					rqstp->rq_thread = stpref;
					STAILQ_INSERT_TAIL(&stpref->st_reqs,
					    rqstp, rq_link);
					mtx_unlock(&stpref->st_lock);
					if (stpref != st)
						rqstp = NULL;
				} else {
					rqstp->rq_thread = st;
					STAILQ_INSERT_TAIL(&st->st_reqs,
					    rqstp, rq_link);
				}
			}
		} while (rqstp == NULL && stat == XPRT_MOREREQS
		    && pool->sp_state != SVCPOOL_CLOSING);

		/*
		 * Move this transport to the end of the active list to
		 * ensure fairness when multiple transports are active.
		 * If this was the last queued request, svc_getreq will end
		 * up calling xprt_inactive to remove from the active list.
		 */
		mtx_lock(&pool->sp_lock);
		xprt->xp_thread = NULL;
		st->st_xprt = NULL;
		if (xprt->xp_active) {
			if (!svc_request_space_available(pool) ||
			    !xprt_assignthread(xprt))
				TAILQ_INSERT_TAIL(&pool->sp_active,
				    xprt, xp_alink);
		}
		mtx_unlock(&pool->sp_lock);
		SVC_RELEASE(xprt);

		/*
		 * Execute what we have queued.
		 */
		sz = 0;
		mtx_lock(&st->st_lock);
		while ((rqstp = STAILQ_FIRST(&st->st_reqs)) != NULL) {
			STAILQ_REMOVE_HEAD(&st->st_reqs, rq_link);
			mtx_unlock(&st->st_lock);
			sz += rqstp->rq_size;
			svc_executereq(rqstp);
			mtx_lock(&st->st_lock);
		}
		mtx_unlock(&st->st_lock);
		svc_change_space_used(pool, -sz);
		mtx_lock(&pool->sp_lock);
	}

	if (st->st_xprt) {
		xprt = st->st_xprt;
		st->st_xprt = NULL;
		SVC_RELEASE(xprt);
	}

	KASSERT(STAILQ_EMPTY(&st->st_reqs), ("stray reqs on exit"));
	LIST_REMOVE(st, st_link);
	pool->sp_threadcount--;

	mtx_unlock(&pool->sp_lock);

	mtx_destroy(&st->st_lock);
	cv_destroy(&st->st_cond);
	mem_free(st, sizeof(*st));

	if (!ismaster)
		wakeup(pool);
}

static void
svc_thread_start(void *arg)
{

	svc_run_internal((SVCPOOL *) arg, FALSE);
	kthread_exit();
}

static void
svc_new_thread(SVCPOOL *pool)
{
	struct thread *td;

	pool->sp_threadcount++;
	kthread_add(svc_thread_start, pool,
	    pool->sp_proc, &td, 0, 0,
	    "%s: service", pool->sp_name);
}

void
svc_run(SVCPOOL *pool)
{
	int i;
	struct proc *p;
	struct thread *td;

	p = curproc;
	td = curthread;
	snprintf(td->td_name, sizeof(td->td_name),
	    "%s: master", pool->sp_name);
	pool->sp_state = SVCPOOL_ACTIVE;
	pool->sp_proc = p;
	pool->sp_lastcreatetime = time_uptime;
	pool->sp_threadcount = 1;

	for (i = 1; i < pool->sp_minthreads; i++) {
		svc_new_thread(pool);
	}

	svc_run_internal(pool, TRUE);

	mtx_lock(&pool->sp_lock);
	while (pool->sp_threadcount > 0)
		msleep(pool, &pool->sp_lock, 0, "svcexit", 0);
	mtx_unlock(&pool->sp_lock);
}

void
svc_exit(SVCPOOL *pool)
{
	SVCTHREAD *st;

	mtx_lock(&pool->sp_lock);

	if (pool->sp_state != SVCPOOL_CLOSING) {
		pool->sp_state = SVCPOOL_CLOSING;
		LIST_FOREACH(st, &pool->sp_idlethreads, st_ilink)
			cv_signal(&st->st_cond);
	}

	mtx_unlock(&pool->sp_lock);
}

bool_t
svc_getargs(struct svc_req *rqstp, xdrproc_t xargs, void *args)
{
	struct mbuf *m;
	XDR xdrs;
	bool_t stat;

	m = rqstp->rq_args;
	rqstp->rq_args = NULL;

	xdrmbuf_create(&xdrs, m, XDR_DECODE);
	stat = xargs(&xdrs, args);
	XDR_DESTROY(&xdrs);

	return (stat);
}

bool_t
svc_freeargs(struct svc_req *rqstp, xdrproc_t xargs, void *args)
{
	XDR xdrs;

	if (rqstp->rq_addr) {
		free(rqstp->rq_addr, M_SONAME);
		rqstp->rq_addr = NULL;
	}

	xdrs.x_op = XDR_FREE;
	return (xargs(&xdrs, args));
}

void
svc_freereq(struct svc_req *rqstp)
{
	SVCTHREAD *st;
	SVCPOOL *pool;

	st = rqstp->rq_thread;
	if (st) {
		pool = st->st_pool;
		if (pool->sp_done)
			pool->sp_done(st, rqstp);
	}

	if (rqstp->rq_auth.svc_ah_ops)
		SVCAUTH_RELEASE(&rqstp->rq_auth);

	if (rqstp->rq_xprt) {
		SVC_RELEASE(rqstp->rq_xprt);
	}

	if (rqstp->rq_addr)
		free(rqstp->rq_addr, M_SONAME);

	if (rqstp->rq_args)
		m_freem(rqstp->rq_args);

	free(rqstp, M_RPC);
}