sys/rpc/svc_vc.c

/*	$NetBSD: svc_vc.c,v 1.7 2000/08/03 00:01:53 fvdl Exp $	*/

/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 *
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 *
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 *
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 *
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 *
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char *sccsid2 = "@(#)svc_tcp.c 1.21 87/08/11 Copyr 1984 Sun Micro";
static char *sccsid = "@(#)svc_tcp.c	2.2 88/08/01 4.0 RPCSRC";
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * svc_vc.c, Server side for Connection Oriented based RPC.
 *
 * Actually implements two flavors of transporter -
 * a tcp rendezvouser (a listner and connection establisher)
 * and a record/tcp stream.
 */

#include <sys/param.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sx.h>
#include <sys/systm.h>
#include <sys/uio.h>

#include <net/vnet.h>

#include <netinet/tcp.h>

#include <rpc/rpc.h>

#include <rpc/krpc.h>
#include <rpc/rpc_com.h>

#include <security/mac/mac_framework.h>

static bool_t svc_vc_rendezvous_recv(SVCXPRT *, struct rpc_msg *,
    struct sockaddr **, struct mbuf **);
static enum xprt_stat svc_vc_rendezvous_stat(SVCXPRT *);
static void svc_vc_rendezvous_destroy(SVCXPRT *);
static bool_t svc_vc_null(void);
static void svc_vc_destroy(SVCXPRT *);
static enum xprt_stat svc_vc_stat(SVCXPRT *);
static bool_t svc_vc_recv(SVCXPRT *, struct rpc_msg *,
    struct sockaddr **, struct mbuf **);
static bool_t svc_vc_reply(SVCXPRT *, struct rpc_msg *,
    struct sockaddr *, struct mbuf *);
static bool_t svc_vc_control(SVCXPRT *xprt, const u_int rq, void *in);
static bool_t svc_vc_rendezvous_control (SVCXPRT *xprt, const u_int rq,
    void *in);
static void svc_vc_backchannel_destroy(SVCXPRT *);
static enum xprt_stat svc_vc_backchannel_stat(SVCXPRT *);
static bool_t svc_vc_backchannel_recv(SVCXPRT *, struct rpc_msg *,
    struct sockaddr **, struct mbuf **);
static bool_t svc_vc_backchannel_reply(SVCXPRT *, struct rpc_msg *,
    struct sockaddr *, struct mbuf *);
static bool_t svc_vc_backchannel_control(SVCXPRT *xprt, const u_int rq,
    void *in);
static SVCXPRT *svc_vc_create_conn(SVCPOOL *pool, struct socket *so,
    struct sockaddr *raddr);
static int svc_vc_accept(struct socket *head, struct socket **sop);
static int svc_vc_soupcall(struct socket *so, void *arg, int waitflag);

static struct xp_ops svc_vc_rendezvous_ops = {
	.xp_recv =	svc_vc_rendezvous_recv,
	.xp_stat =	svc_vc_rendezvous_stat,
	.xp_reply =	(bool_t (*)(SVCXPRT *, struct rpc_msg *,
		struct sockaddr *, struct mbuf *))svc_vc_null,
	.xp_destroy =	svc_vc_rendezvous_destroy,
	.xp_control =	svc_vc_rendezvous_control
};

static struct xp_ops svc_vc_ops = {
	.xp_recv =	svc_vc_recv,
	.xp_stat =	svc_vc_stat,
	.xp_reply =	svc_vc_reply,
	.xp_destroy =	svc_vc_destroy,
	.xp_control =	svc_vc_control
};

static struct xp_ops svc_vc_backchannel_ops = {
	.xp_recv =	svc_vc_backchannel_recv,
	.xp_stat =	svc_vc_backchannel_stat,
	.xp_reply =	svc_vc_backchannel_reply,
	.xp_destroy =	svc_vc_backchannel_destroy,
	.xp_control =	svc_vc_backchannel_control
};

/*
 * Usage:
 *	xprt = svc_vc_create(sock, send_buf_size, recv_buf_size);
 *
 * Creates, registers, and returns a (rpc) tcp based transporter.
 * Once *xprt is initialized, it is registered as a transporter
 * see (svc.h, xprt_register).  This routine returns
 * a NULL if a problem occurred.
 *
 * The filedescriptor passed in is expected to refer to a bound, but
 * not yet connected socket.
 *
 * Since streams do buffered io similar to stdio, the caller can specify
 * how big the send and receive buffers are via the second and third parms;
 * 0 => use the system default.
 */
SVCXPRT *
svc_vc_create(SVCPOOL *pool, struct socket *so, size_t sendsize,
    size_t recvsize)
{
	SVCXPRT *xprt;
	struct sockaddr* sa;
	int error;

	if (so->so_state & SS_ISCONNECTED) {
		error = so->so_proto->pr_usrreqs->pru_peeraddr(so, &sa);
		if (error)
			return (NULL);
		xprt = svc_vc_create_conn(pool, so, sa);
		free(sa, M_SONAME);
		return (xprt);
	}

	xprt = svc_xprt_alloc();
	sx_init(&xprt->xp_lock, "xprt->xp_lock");
	xprt->xp_pool = pool;
	xprt->xp_socket = so;
	xprt->xp_p1 = NULL;
	xprt->xp_p2 = NULL;
	xprt->xp_ops = &svc_vc_rendezvous_ops;

	error = so->so_proto->pr_usrreqs->pru_sockaddr(so, &sa);
	if (error) {
		goto cleanup_svc_vc_create;
	}

	memcpy(&xprt->xp_ltaddr, sa, sa->sa_len);
	free(sa, M_SONAME);

	xprt_register(xprt);

	solisten(so, SOMAXCONN, curthread);

	SOCKBUF_LOCK(&so->so_rcv);
	xprt->xp_upcallset = 1;
	soupcall_set(so, SO_RCV, svc_vc_soupcall, xprt);
	SOCKBUF_UNLOCK(&so->so_rcv);

	return (xprt);
cleanup_svc_vc_create:
	if (xprt)
		svc_xprt_free(xprt);
	return (NULL);
}

/*
 * Create a new transport for a socket optained via soaccept().
 */
SVCXPRT *
svc_vc_create_conn(SVCPOOL *pool, struct socket *so, struct sockaddr *raddr)
{
	SVCXPRT *xprt = NULL;
	struct cf_conn *cd = NULL;
	struct sockaddr* sa = NULL;
	struct sockopt opt;
	int one = 1;
	int error;

	bzero(&opt, sizeof(struct sockopt));
	opt.sopt_dir = SOPT_SET;
	opt.sopt_level = SOL_SOCKET;
	opt.sopt_name = SO_KEEPALIVE;
	opt.sopt_val = &one;
	opt.sopt_valsize = sizeof(one);
	error = sosetopt(so, &opt);
	if (error) {
		return (NULL);
	}

	if (so->so_proto->pr_protocol == IPPROTO_TCP) {
		bzero(&opt, sizeof(struct sockopt));
		opt.sopt_dir = SOPT_SET;
		opt.sopt_level = IPPROTO_TCP;
		opt.sopt_name = TCP_NODELAY;
		opt.sopt_val = &one;
		opt.sopt_valsize = sizeof(one);
		error = sosetopt(so, &opt);
		if (error) {
			return (NULL);
		}
	}

	cd = mem_alloc(sizeof(*cd));
	cd->strm_stat = XPRT_IDLE;

	xprt = svc_xprt_alloc();
	sx_init(&xprt->xp_lock, "xprt->xp_lock");
	xprt->xp_pool = pool;
	xprt->xp_socket = so;
	xprt->xp_p1 = cd;
	xprt->xp_p2 = NULL;
	xprt->xp_ops = &svc_vc_ops;

	/*
	 * See http://www.connectathon.org/talks96/nfstcp.pdf - client
	 * has a 5 minute timer, server has a 6 minute timer.
	 */
	xprt->xp_idletimeout = 6 * 60;

	memcpy(&xprt->xp_rtaddr, raddr, raddr->sa_len);

	error = so->so_proto->pr_usrreqs->pru_sockaddr(so, &sa);
	if (error)
		goto cleanup_svc_vc_create;

	memcpy(&xprt->xp_ltaddr, sa, sa->sa_len);
	free(sa, M_SONAME);

	xprt_register(xprt);

	SOCKBUF_LOCK(&so->so_rcv);
	xprt->xp_upcallset = 1;
	soupcall_set(so, SO_RCV, svc_vc_soupcall, xprt);
	SOCKBUF_UNLOCK(&so->so_rcv);

	/*
	 * Throw the transport into the active list in case it already
	 * has some data buffered.
	 */
	sx_xlock(&xprt->xp_lock);
	xprt_active(xprt);
	sx_xunlock(&xprt->xp_lock);

	return (xprt);
cleanup_svc_vc_create:
	if (xprt) {
		mem_free(xprt, sizeof(*xprt));
	}
	if (cd)
		mem_free(cd, sizeof(*cd));
	return (NULL);
}

/*
 * Create a new transport for a backchannel on a clnt_vc socket.
 */
SVCXPRT *
svc_vc_create_backchannel(SVCPOOL *pool)
{
	SVCXPRT *xprt = NULL;
	struct cf_conn *cd = NULL;

	cd = mem_alloc(sizeof(*cd));
	cd->strm_stat = XPRT_IDLE;

	xprt = svc_xprt_alloc();
	sx_init(&xprt->xp_lock, "xprt->xp_lock");
	xprt->xp_pool = pool;
	xprt->xp_socket = NULL;
	xprt->xp_p1 = cd;
	xprt->xp_p2 = NULL;
	xprt->xp_ops = &svc_vc_backchannel_ops;
	return (xprt);
}

/*
 * This does all of the accept except the final call to soaccept. The
 * caller will call soaccept after dropping its locks (soaccept may
 * call malloc).
 */
int
svc_vc_accept(struct socket *head, struct socket **sop)
{
	int error = 0;
	struct socket *so;

	if ((head->so_options & SO_ACCEPTCONN) == 0) {
		error = EINVAL;
		goto done;
	}
#ifdef MAC
	error = mac_socket_check_accept(curthread->td_ucred, head);
	if (error != 0)
		goto done;
#endif
	ACCEPT_LOCK();
	if (TAILQ_EMPTY(&head->so_comp)) {
		ACCEPT_UNLOCK();
		error = EWOULDBLOCK;
		goto done;
	}
	so = TAILQ_FIRST(&head->so_comp);
	KASSERT(!(so->so_qstate & SQ_INCOMP), ("svc_vc_accept: so SQ_INCOMP"));
	KASSERT(so->so_qstate & SQ_COMP, ("svc_vc_accept: so not SQ_COMP"));

	/*
	 * Before changing the flags on the socket, we have to bump the
	 * reference count.  Otherwise, if the protocol calls sofree(),
	 * the socket will be released due to a zero refcount.
	 * XXX might not need soref() since this is simpler than kern_accept.
	 */
	SOCK_LOCK(so);			/* soref() and so_state update */
	soref(so);			/* file descriptor reference */

	TAILQ_REMOVE(&head->so_comp, so, so_list);
	head->so_qlen--;
	so->so_state |= (head->so_state & SS_NBIO);
	so->so_qstate &= ~SQ_COMP;
	so->so_head = NULL;

	SOCK_UNLOCK(so);
	ACCEPT_UNLOCK();

	*sop = so;

	/* connection has been removed from the listen queue */
	KNOTE_UNLOCKED(&head->so_rcv.sb_sel.si_note, 0);
done:
	return (error);
}

/*ARGSUSED*/
static bool_t
svc_vc_rendezvous_recv(SVCXPRT *xprt, struct rpc_msg *msg,
    struct sockaddr **addrp, struct mbuf **mp)
{
	struct socket *so = NULL;
	struct sockaddr *sa = NULL;
	int error;
	SVCXPRT *new_xprt;

	/*
	 * The socket upcall calls xprt_active() which will eventually
	 * cause the server to call us here. We attempt to accept a
	 * connection from the socket and turn it into a new
	 * transport. If the accept fails, we have drained all pending
	 * connections so we call xprt_inactive().
	 */
	sx_xlock(&xprt->xp_lock);

	error = svc_vc_accept(xprt->xp_socket, &so);

	if (error == EWOULDBLOCK) {
		/*
		 * We must re-test for new connections after taking
		 * the lock to protect us in the case where a new
		 * connection arrives after our call to accept fails
		 * with EWOULDBLOCK. The pool lock protects us from
		 * racing the upcall after our TAILQ_EMPTY() call
		 * returns false.
		 */
		ACCEPT_LOCK();
		mtx_lock(&xprt->xp_pool->sp_lock);
		if (TAILQ_EMPTY(&xprt->xp_socket->so_comp))
			xprt_inactive_locked(xprt);
		mtx_unlock(&xprt->xp_pool->sp_lock);
		ACCEPT_UNLOCK();
		sx_xunlock(&xprt->xp_lock);
		return (FALSE);
	}

	if (error) {
		SOCKBUF_LOCK(&xprt->xp_socket->so_rcv);
		if (xprt->xp_upcallset) {
			xprt->xp_upcallset = 0;
			soupcall_clear(xprt->xp_socket, SO_RCV);
		}
		SOCKBUF_UNLOCK(&xprt->xp_socket->so_rcv);
		xprt_inactive(xprt);
		sx_xunlock(&xprt->xp_lock);
		return (FALSE);
	}

	sx_xunlock(&xprt->xp_lock);

	sa = 0;
	error = soaccept(so, &sa);

	if (error) {
		/*
		 * XXX not sure if I need to call sofree or soclose here.
		 */
		if (sa)
			free(sa, M_SONAME);
		return (FALSE);
	}

	/*
	 * svc_vc_create_conn will call xprt_register - we don't need
	 * to do anything with the new connection except derefence it.
	 */
	new_xprt = svc_vc_create_conn(xprt->xp_pool, so, sa);
	if (!new_xprt) {
		soclose(so);
	} else {
		SVC_RELEASE(new_xprt);
	}

	free(sa, M_SONAME);

	return (FALSE); /* there is never an rpc msg to be processed */
}

/*ARGSUSED*/
static enum xprt_stat
svc_vc_rendezvous_stat(SVCXPRT *xprt)
{

	return (XPRT_IDLE);
}

static void
svc_vc_destroy_common(SVCXPRT *xprt)
{
	SOCKBUF_LOCK(&xprt->xp_socket->so_rcv);
	if (xprt->xp_upcallset) {
		xprt->xp_upcallset = 0;
		soupcall_clear(xprt->xp_socket, SO_RCV);
	}
	SOCKBUF_UNLOCK(&xprt->xp_socket->so_rcv);

	sx_destroy(&xprt->xp_lock);
	if (xprt->xp_socket)
		(void)soclose(xprt->xp_socket);

	if (xprt->xp_netid)
		(void) mem_free(xprt->xp_netid, strlen(xprt->xp_netid) + 1);
	svc_xprt_free(xprt);
}

static void
svc_vc_rendezvous_destroy(SVCXPRT *xprt)
{

	svc_vc_destroy_common(xprt);
}

static void
svc_vc_destroy(SVCXPRT *xprt)
{
	struct cf_conn *cd = (struct cf_conn *)xprt->xp_p1;

	svc_vc_destroy_common(xprt);

	if (cd->mreq)
		m_freem(cd->mreq);
	if (cd->mpending)
		m_freem(cd->mpending);
	mem_free(cd, sizeof(*cd));
}

static void
svc_vc_backchannel_destroy(SVCXPRT *xprt)
{
	struct cf_conn *cd = (struct cf_conn *)xprt->xp_p1;
	struct mbuf *m, *m2;

	svc_xprt_free(xprt);
	m = cd->mreq;
	while (m != NULL) {
		m2 = m;
		m = m->m_nextpkt;
		m_freem(m2);
	}
	mem_free(cd, sizeof(*cd));
}

/*ARGSUSED*/
static bool_t
svc_vc_control(SVCXPRT *xprt, const u_int rq, void *in)
{
	return (FALSE);
}

static bool_t
svc_vc_rendezvous_control(SVCXPRT *xprt, const u_int rq, void *in)
{

	return (FALSE);
}

static bool_t
svc_vc_backchannel_control(SVCXPRT *xprt, const u_int rq, void *in)
{

	return (FALSE);
}

static enum xprt_stat
svc_vc_stat(SVCXPRT *xprt)
{
	struct cf_conn *cd;
	struct mbuf *m;
	size_t n;

	cd = (struct cf_conn *)(xprt->xp_p1);

	if (cd->strm_stat == XPRT_DIED)
		return (XPRT_DIED);

	/*
	 * Return XPRT_MOREREQS if we have buffered data and we are
	 * mid-record or if we have enough data for a record
	 * marker. Since this is only a hint, we read mpending and
	 * resid outside the lock. We do need to take the lock if we
	 * have to traverse the mbuf chain.
	 */
	if (cd->mpending) {
		if (cd->resid)
			return (XPRT_MOREREQS);
		n = 0;
		sx_xlock(&xprt->xp_lock);
		m = cd->mpending;
		while (m && n < sizeof(uint32_t)) {
			n += m->m_len;
			m = m->m_next;
		}
		sx_xunlock(&xprt->xp_lock);
		if (n >= sizeof(uint32_t))
			return (XPRT_MOREREQS);
	}

	if (soreadable(xprt->xp_socket))
		return (XPRT_MOREREQS);

	return (XPRT_IDLE);
}

static enum xprt_stat
svc_vc_backchannel_stat(SVCXPRT *xprt)
{
	struct cf_conn *cd;

	cd = (struct cf_conn *)(xprt->xp_p1);

	if (cd->mreq != NULL)
		return (XPRT_MOREREQS);

	return (XPRT_IDLE);
}

static bool_t
svc_vc_recv(SVCXPRT *xprt, struct rpc_msg *msg,
    struct sockaddr **addrp, struct mbuf **mp)
{
	struct cf_conn *cd = (struct cf_conn *) xprt->xp_p1;
	struct uio uio;
	struct mbuf *m;
	XDR xdrs;
	int error, rcvflag;

	/*
	 * Serialise access to the socket and our own record parsing
	 * state.
	 */
	sx_xlock(&xprt->xp_lock);

	for (;;) {
		/*
		 * If we have an mbuf chain in cd->mpending, try to parse a
		 * record from it, leaving the result in cd->mreq. If we don't
		 * have a complete record, leave the partial result in
		 * cd->mreq and try to read more from the socket.
		 */
		if (cd->mpending) {
			/*
			 * If cd->resid is non-zero, we have part of the
			 * record already, otherwise we are expecting a record
			 * marker.
			 */
			if (!cd->resid) {
				/*
				 * See if there is enough data buffered to
				 * make up a record marker. Make sure we can
				 * handle the case where the record marker is
				 * split across more than one mbuf.
				 */
				size_t n = 0;
				uint32_t header;

				m = cd->mpending;
				while (n < sizeof(uint32_t) && m) {
					n += m->m_len;
					m = m->m_next;
				}
				if (n < sizeof(uint32_t))
					goto readmore;
				m_copydata(cd->mpending, 0, sizeof(header),
				    (char *)&header);
				header = ntohl(header);
				cd->eor = (header & 0x80000000) != 0;
				cd->resid = header & 0x7fffffff;
				m_adj(cd->mpending, sizeof(uint32_t));
			}

			/*
			 * Start pulling off mbufs from cd->mpending
			 * until we either have a complete record or
			 * we run out of data. We use m_split to pull
			 * data - it will pull as much as possible and
			 * split the last mbuf if necessary.
			 */
			while (cd->mpending && cd->resid) {
				m = cd->mpending;
				if (cd->mpending->m_next
				    || cd->mpending->m_len > cd->resid)
					cd->mpending = m_split(cd->mpending,
					    cd->resid, M_WAITOK);
				else
					cd->mpending = NULL;
				if (cd->mreq)
					m_last(cd->mreq)->m_next = m;
				else
					cd->mreq = m;
				while (m) {
					cd->resid -= m->m_len;
					m = m->m_next;
				}
			}

			/*
			 * If cd->resid is zero now, we have managed to
			 * receive a record fragment from the stream. Check
			 * for the end-of-record mark to see if we need more.
			 */
			if (cd->resid == 0) {
				if (!cd->eor)
					continue;

				/*
				 * Success - we have a complete record in
				 * cd->mreq.
				 */
				xdrmbuf_create(&xdrs, cd->mreq, XDR_DECODE);
				cd->mreq = NULL;
				sx_xunlock(&xprt->xp_lock);

				if (! xdr_callmsg(&xdrs, msg)) {
					XDR_DESTROY(&xdrs);
					return (FALSE);
				}

				*addrp = NULL;
				*mp = xdrmbuf_getall(&xdrs);
				XDR_DESTROY(&xdrs);

				return (TRUE);
			}
		}

	readmore:
		/*
		 * The socket upcall calls xprt_active() which will eventually
		 * cause the server to call us here. We attempt to
		 * read as much as possible from the socket and put
		 * the result in cd->mpending. If the read fails,
		 * we have drained both cd->mpending and the socket so
		 * we can call xprt_inactive().
		 */
		uio.uio_resid = 1000000000;
		uio.uio_td = curthread;
		m = NULL;
		rcvflag = MSG_DONTWAIT;
		error = soreceive(xprt->xp_socket, NULL, &uio, &m, NULL,
		    &rcvflag);

		if (error == EWOULDBLOCK) {
			/*
			 * We must re-test for readability after
			 * taking the lock to protect us in the case
			 * where a new packet arrives on the socket
			 * after our call to soreceive fails with
			 * EWOULDBLOCK. The pool lock protects us from
			 * racing the upcall after our soreadable()
			 * call returns false.
			 */
			mtx_lock(&xprt->xp_pool->sp_lock);
			if (!soreadable(xprt->xp_socket))
				xprt_inactive_locked(xprt);
			mtx_unlock(&xprt->xp_pool->sp_lock);
			sx_xunlock(&xprt->xp_lock);
			return (FALSE);
		}

		if (error) {
			SOCKBUF_LOCK(&xprt->xp_socket->so_rcv);
			if (xprt->xp_upcallset) {
				xprt->xp_upcallset = 0;
				soupcall_clear(xprt->xp_socket, SO_RCV);
			}
			SOCKBUF_UNLOCK(&xprt->xp_socket->so_rcv);
			xprt_inactive(xprt);
			cd->strm_stat = XPRT_DIED;
			sx_xunlock(&xprt->xp_lock);
			return (FALSE);
		}

		if (!m) {
			/*
			 * EOF - the other end has closed the socket.
			 */
			xprt_inactive(xprt);
			cd->strm_stat = XPRT_DIED;
			sx_xunlock(&xprt->xp_lock);
			return (FALSE);
		}

		if (cd->mpending)
			m_last(cd->mpending)->m_next = m;
		else
			cd->mpending = m;
	}
}

static bool_t
svc_vc_backchannel_recv(SVCXPRT *xprt, struct rpc_msg *msg,
    struct sockaddr **addrp, struct mbuf **mp)
{
	struct cf_conn *cd = (struct cf_conn *) xprt->xp_p1;
	struct ct_data *ct;
	struct mbuf *m;
	XDR xdrs;

	sx_xlock(&xprt->xp_lock);
	ct = (struct ct_data *)xprt->xp_p2;
	if (ct == NULL) {
		sx_xunlock(&xprt->xp_lock);
		return (FALSE);
	}
	mtx_lock(&ct->ct_lock);
	m = cd->mreq;
	if (m == NULL) {
		xprt_inactive(xprt);
		mtx_unlock(&ct->ct_lock);
		sx_xunlock(&xprt->xp_lock);
		return (FALSE);
	}
	cd->mreq = m->m_nextpkt;
	mtx_unlock(&ct->ct_lock);
	sx_xunlock(&xprt->xp_lock);

	xdrmbuf_create(&xdrs, m, XDR_DECODE);
	if (! xdr_callmsg(&xdrs, msg)) {
		XDR_DESTROY(&xdrs);
		return (FALSE);
	}
	*addrp = NULL;
	*mp = xdrmbuf_getall(&xdrs);
	XDR_DESTROY(&xdrs);
	return (TRUE);
}

static bool_t
svc_vc_reply(SVCXPRT *xprt, struct rpc_msg *msg,
    struct sockaddr *addr, struct mbuf *m)
{
	XDR xdrs;
	struct mbuf *mrep;
	bool_t stat = TRUE;
	int error;

	/*
	 * Leave space for record mark.
	 */
	MGETHDR(mrep, M_WAITOK, MT_DATA);
	mrep->m_len = 0;
	mrep->m_data += sizeof(uint32_t);

	xdrmbuf_create(&xdrs, mrep, XDR_ENCODE);

	if (msg->rm_reply.rp_stat == MSG_ACCEPTED &&
	    msg->rm_reply.rp_acpt.ar_stat == SUCCESS) {
		if (!xdr_replymsg(&xdrs, msg))
			stat = FALSE;
		else
			xdrmbuf_append(&xdrs, m);
	} else {
		stat = xdr_replymsg(&xdrs, msg);
	}

	if (stat) {
		m_fixhdr(mrep);

		/*
		 * Prepend a record marker containing the reply length.
		 */
		M_PREPEND(mrep, sizeof(uint32_t), M_WAITOK);
		*mtod(mrep, uint32_t *) =
			htonl(0x80000000 | (mrep->m_pkthdr.len
				- sizeof(uint32_t)));
		error = sosend(xprt->xp_socket, NULL, NULL, mrep, NULL,
		    0, curthread);
		if (!error) {
			stat = TRUE;
		}
	} else {
		m_freem(mrep);
	}

	XDR_DESTROY(&xdrs);
	xprt->xp_p2 = NULL;

	return (stat);
}

static bool_t
svc_vc_backchannel_reply(SVCXPRT *xprt, struct rpc_msg *msg,
    struct sockaddr *addr, struct mbuf *m)
{
	struct ct_data *ct;
	XDR xdrs;
	struct mbuf *mrep;
	bool_t stat = TRUE;
	int error;

	/*
	 * Leave space for record mark.
	 */
	MGETHDR(mrep, M_WAITOK, MT_DATA);
	mrep->m_len = 0;
	mrep->m_data += sizeof(uint32_t);

	xdrmbuf_create(&xdrs, mrep, XDR_ENCODE);

	if (msg->rm_reply.rp_stat == MSG_ACCEPTED &&
	    msg->rm_reply.rp_acpt.ar_stat == SUCCESS) {
		if (!xdr_replymsg(&xdrs, msg))
			stat = FALSE;
		else
			xdrmbuf_append(&xdrs, m);
	} else {
		stat = xdr_replymsg(&xdrs, msg);
	}

	if (stat) {
		m_fixhdr(mrep);

		/*
		 * Prepend a record marker containing the reply length.
		 */
		M_PREPEND(mrep, sizeof(uint32_t), M_WAITOK);
		*mtod(mrep, uint32_t *) =
			htonl(0x80000000 | (mrep->m_pkthdr.len
				- sizeof(uint32_t)));
		sx_xlock(&xprt->xp_lock);
		ct = (struct ct_data *)xprt->xp_p2;
		if (ct != NULL)
			error = sosend(ct->ct_socket, NULL, NULL, mrep, NULL,
			    0, curthread);
		else
			error = EPIPE;
		sx_xunlock(&xprt->xp_lock);
		if (!error) {
			stat = TRUE;
		}
	} else {
		m_freem(mrep);
	}

	XDR_DESTROY(&xdrs);

	return (stat);
}

static bool_t
svc_vc_null()
{

	return (FALSE);
}

static int
svc_vc_soupcall(struct socket *so, void *arg, int waitflag)
{
	SVCXPRT *xprt = (SVCXPRT *) arg;

	xprt_active(xprt);
	return (SU_OK);
}

#if 0
/*
 * Get the effective UID of the sending process. Used by rpcbind, keyserv
 * and rpc.yppasswdd on AF_LOCAL.
 */
int
__rpc_get_local_uid(SVCXPRT *transp, uid_t *uid) {
	int sock, ret;
	gid_t egid;
	uid_t euid;
	struct sockaddr *sa;

	sock = transp->xp_fd;
	sa = (struct sockaddr *)transp->xp_rtaddr;
	if (sa->sa_family == AF_LOCAL) {
		ret = getpeereid(sock, &euid, &egid);
		if (ret == 0)
			*uid = euid;
		return (ret);
	} else
		return (-1);
}
#endif