/*      $NetBSD: clnt_vc.c,v 1.4 2000/07/14 08:40:42 fvdl Exp $ */

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 */

/*
 * clnt_tcp.c, Implements a TCP/IP based, client side RPC.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * TCP based RPC supports 'batched calls'.
 * A sequence of calls may be batched-up in a send buffer.  The rpc call
 * return immediately to the client even though the call was not necessarily
 * sent.  The batching occurs if the results' xdr routine is NULL (0) AND
 * the rpc timeout value is zero (see clnt.h, rpc).
 *
 * Clients should NOT casually batch calls that in fact return results; that is,
 * the server side should be aware that a call is batched and not produce any
 * return message.  Batched calls that produce many result messages can
 * deadlock (netlock) the client and the server....
 *
 * Now go hang yourself.
 */

#include "namespace.h"
#include "reentrant.h"
#include <sys/types.h>
#include <sys/poll.h>
#include <sys/syslog.h>
#include <sys/socket.h>
#include <sys/tree.h>
#include <sys/un.h>
#include <sys/uio.h>

#include <arpa/inet.h>
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <pthread.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>

#include <rpc/rpc.h>
#include <rpc/rpcsec_gss.h>
#include "un-namespace.h"
#include "rpc_com.h"
#include "mt_misc.h"

#define MCALL_MSG_SIZE 24

struct cmessage {
        struct cmsghdr cmsg;
        struct cmsgcred cmcred;
};

static enum clnt_stat clnt_vc_call(CLIENT *, rpcproc_t, xdrproc_t, void *,
    xdrproc_t, void *, struct timeval);
static void clnt_vc_geterr(CLIENT *, struct rpc_err *);
static bool_t clnt_vc_freeres(CLIENT *, xdrproc_t, void *);
static void clnt_vc_abort(CLIENT *);
static bool_t clnt_vc_control(CLIENT *, u_int, void *);
static void clnt_vc_destroy(CLIENT *);
static struct clnt_ops *clnt_vc_ops(void);
static bool_t time_not_ok(struct timeval *);
static int read_vc(void *, void *, int);
static int write_vc(void *, void *, int);
static int __msgwrite(int, void *, size_t);
static int __msgread(int, void *, size_t);

struct ct_data {
        int             ct_fd;          /* connection's fd */
        bool_t          ct_closeit;     /* close it on destroy */
        struct timeval  ct_wait;        /* wait interval in milliseconds */
        bool_t          ct_waitset;     /* wait set by clnt_control? */
        struct netbuf   ct_addr;        /* remote addr */
        struct rpc_err  ct_error;
        union {
                char    ct_mcallc[MCALL_MSG_SIZE];      /* marshalled callmsg */
                u_int32_t ct_mcalli;
        } ct_u;
        u_int           ct_mpos;        /* pos after marshal */
        XDR             ct_xdrs;        /* XDR stream */
};

/*
 *      This machinery implements per-fd locks for MT-safety.  It is not
 *      sufficient to do per-CLIENT handle locks for MT-safety because a
 *      user may create more than one CLIENT handle with the same fd behind
 *      it.  Therefore, we allocate an associative array of flags and condition
 *      variables (vc_fd).  The flags and the array are protected by the
 *      clnt_fd_lock mutex.  vc_fd_lock[fd] == 1 => a call is active on some
 *      CLIENT handle created for that fd.  The current implementation holds
 *      locks across the entire RPC and reply.  Yes, this is silly, and as soon
 *      as this code is proven to work, this should be the first thing fixed.
 *      One step at a time.
 */
struct vc_fd {
        RB_ENTRY(vc_fd) vc_link;
        int fd;
        mutex_t mtx;
};
static inline int
cmp_vc_fd(struct vc_fd *a, struct vc_fd *b)
{
       if (a->fd > b->fd) {
               return (1);
       } else if (a->fd < b->fd) {
               return (-1);
       } else {
               return (0);
       }
}
RB_HEAD(vc_fd_list, vc_fd);
RB_PROTOTYPE(vc_fd_list, vc_fd, vc_link, cmp_vc_fd);
RB_GENERATE(vc_fd_list, vc_fd, vc_link, cmp_vc_fd);
struct vc_fd_list vc_fd_head = RB_INITIALIZER(&vc_fd_head);

/*
 * Find the lock structure for the given file descriptor, or initialize it if
 * it does not already exist.  The clnt_fd_lock mutex must be held.
 */
static struct vc_fd *
vc_fd_find(int fd)
{
        struct vc_fd key, *elem;

        key.fd = fd;
        elem = RB_FIND(vc_fd_list, &vc_fd_head, &key);
        if (elem == NULL) {
                elem = calloc(1, sizeof(*elem));
                elem->fd = fd;
                mutex_init(&elem->mtx, NULL);
                RB_INSERT(vc_fd_list, &vc_fd_head, elem);
        }
        return (elem);
}

static void
release_fd_lock(struct vc_fd *elem, sigset_t mask)
{
        mutex_unlock(&elem->mtx);
        thr_sigsetmask(SIG_SETMASK, &mask, NULL);
}

static const char clnt_vc_errstr[] = "%s : %s";
static const char clnt_vc_str[] = "clnt_vc_create";
static const char __no_mem_str[] = "out of memory";

/*
 * Create a client handle for a connection.
 * Default options are set, which the user can change using clnt_control()'s.
 * The rpc/vc package does buffering similar to stdio, so the client
 * must pick send and receive buffer sizes, 0 => use the default.
 * NB: fd is copied into a private area.
 * NB: The rpch->cl_auth is set null authentication. Caller may wish to
 * set this something more useful.
 *
 * fd should be an open socket
 *
 * fd - open file descriptor
 * raddr - servers address
 * prog  - program number
 * vers  - version number
 * sendsz - buffer send size
 * recvsz - buffer recv size
 */
CLIENT *
clnt_vc_create(int fd, const struct netbuf *raddr, const rpcprog_t prog,
    const rpcvers_t vers, u_int sendsz, u_int recvsz)
{
        CLIENT *cl;                     /* client handle */
        struct ct_data *ct = NULL;      /* client handle */
        struct timeval now;
        struct rpc_msg call_msg;
        static u_int32_t disrupt;
        struct sockaddr_storage ss;
        socklen_t slen;
        struct __rpc_sockinfo si;

        if (disrupt == 0)
                disrupt = (u_int32_t)(long)raddr;

        cl = (CLIENT *)mem_alloc(sizeof (*cl));
        ct = (struct ct_data *)mem_alloc(sizeof (*ct));
        if ((cl == (CLIENT *)NULL) || (ct == (struct ct_data *)NULL)) {
                (void) syslog(LOG_ERR, clnt_vc_errstr,
                    clnt_vc_str, __no_mem_str);
                rpc_createerr.cf_stat = RPC_SYSTEMERROR;
                rpc_createerr.cf_error.re_errno = errno;
                goto err;
        }
        ct->ct_addr.buf = NULL;

        /*
         * XXX - fvdl connecting while holding a mutex?
         */
        slen = sizeof ss;
        if (_getpeername(fd, (struct sockaddr *)(void *)&ss, &slen) < 0) {
                if (errno != ENOTCONN) {
                        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
                        rpc_createerr.cf_error.re_errno = errno;
                        mutex_unlock(&clnt_fd_lock);
                        goto err;
                }
                if (_connect(fd, (struct sockaddr *)raddr->buf, raddr->len) < 0){
                        rpc_createerr.cf_stat = RPC_SYSTEMERROR;
                        rpc_createerr.cf_error.re_errno = errno;
                        mutex_unlock(&clnt_fd_lock);
                        goto err;
                }
        }
        mutex_unlock(&clnt_fd_lock);
        if (!__rpc_fd2sockinfo(fd, &si))
                goto err;

        ct->ct_closeit = FALSE;

        /*
         * Set up private data struct
         */
        ct->ct_fd = fd;
        ct->ct_wait.tv_usec = 0;
        ct->ct_waitset = FALSE;
        ct->ct_addr.buf = malloc(raddr->maxlen);
        if (ct->ct_addr.buf == NULL)
                goto err;
        memcpy(ct->ct_addr.buf, raddr->buf, raddr->len);
        ct->ct_addr.len = raddr->len;
        ct->ct_addr.maxlen = raddr->maxlen;

        /*
         * Initialize call message
         */
        (void)gettimeofday(&now, NULL);
        call_msg.rm_xid = ((u_int32_t)++disrupt) ^ __RPC_GETXID(&now);
        call_msg.rm_direction = CALL;
        call_msg.rm_call.cb_rpcvers = RPC_MSG_VERSION;
        call_msg.rm_call.cb_prog = (u_int32_t)prog;
        call_msg.rm_call.cb_vers = (u_int32_t)vers;

        /*
         * pre-serialize the static part of the call msg and stash it away
         */
        xdrmem_create(&(ct->ct_xdrs), ct->ct_u.ct_mcallc, MCALL_MSG_SIZE,
            XDR_ENCODE);
        if (! xdr_callhdr(&(ct->ct_xdrs), &call_msg)) {
                if (ct->ct_closeit) {
                        (void)_close(fd);
                }
                goto err;
        }
        ct->ct_mpos = XDR_GETPOS(&(ct->ct_xdrs));
        XDR_DESTROY(&(ct->ct_xdrs));
        assert(ct->ct_mpos + sizeof(uint32_t) <= MCALL_MSG_SIZE);

        /*
         * Create a client handle which uses xdrrec for serialization
         * and authnone for authentication.
         */
        cl->cl_ops = clnt_vc_ops();
        cl->cl_private = ct;
        cl->cl_auth = authnone_create();
        sendsz = __rpc_get_t_size(si.si_af, si.si_proto, (int)sendsz);
        recvsz = __rpc_get_t_size(si.si_af, si.si_proto, (int)recvsz);
        xdrrec_create(&(ct->ct_xdrs), sendsz, recvsz,
            cl->cl_private, read_vc, write_vc);
        return (cl);

err:
        if (ct) {
                if (ct->ct_addr.len)
                        mem_free(ct->ct_addr.buf, ct->ct_addr.len);
                mem_free(ct, sizeof (struct ct_data));
        }
        if (cl)
                mem_free(cl, sizeof (CLIENT));
        return ((CLIENT *)NULL);
}

static enum clnt_stat
clnt_vc_call(CLIENT *cl, rpcproc_t proc, xdrproc_t xdr_args, void *args_ptr,
    xdrproc_t xdr_results, void *results_ptr, struct timeval timeout)
{
        struct ct_data *ct = (struct ct_data *) cl->cl_private;
        XDR *xdrs = &(ct->ct_xdrs);
        struct rpc_msg reply_msg;
        struct vc_fd *elem;
        u_int32_t x_id;
        u_int32_t *msg_x_id = &ct->ct_u.ct_mcalli;    /* yuk */
        bool_t shipnow;
        int refreshes = 2;
        sigset_t mask, newmask;
        bool_t reply_stat;

        assert(cl != NULL);

        sigfillset(&newmask);
        thr_sigsetmask(SIG_SETMASK, &newmask, &mask);
        mutex_lock(&clnt_fd_lock);
        elem = vc_fd_find(ct->ct_fd);
        mutex_unlock(&clnt_fd_lock);
        mutex_lock(&elem->mtx);
        if (!ct->ct_waitset) {
                /* If time is not within limits, we ignore it. */
                if (time_not_ok(&timeout) == FALSE)
                        ct->ct_wait = timeout;
        }

        shipnow =
            (xdr_results == NULL && timeout.tv_sec == 0
            && timeout.tv_usec == 0) ? FALSE : TRUE;

call_again:
        xdrs->x_op = XDR_ENCODE;
        ct->ct_error.re_status = RPC_SUCCESS;
        x_id = ntohl(--(*msg_x_id));

        if (cl->cl_auth->ah_cred.oa_flavor != RPCSEC_GSS) {
                if ((! XDR_PUTBYTES(xdrs, ct->ct_u.ct_mcallc, ct->ct_mpos)) ||
                    (! XDR_PUTINT32(xdrs, &proc)) ||
                    (! AUTH_MARSHALL(cl->cl_auth, xdrs)) ||
                    (! (*xdr_args)(xdrs, args_ptr))) {
                        if (ct->ct_error.re_status == RPC_SUCCESS)
                                ct->ct_error.re_status = RPC_CANTENCODEARGS;
                        (void)xdrrec_endofrecord(xdrs, TRUE);
                        release_fd_lock(elem, mask);
                        return (ct->ct_error.re_status);
                }
        } else {
                *(uint32_t *) &ct->ct_u.ct_mcallc[ct->ct_mpos] = htonl(proc);
                if (! __rpc_gss_wrap(cl->cl_auth, ct->ct_u.ct_mcallc,
                        ct->ct_mpos + sizeof(uint32_t),
                        xdrs, xdr_args, args_ptr)) {
                        if (ct->ct_error.re_status == RPC_SUCCESS)
                                ct->ct_error.re_status = RPC_CANTENCODEARGS;
                        (void)xdrrec_endofrecord(xdrs, TRUE);
                        release_fd_lock(elem, mask);
                        return (ct->ct_error.re_status);
                }
        }
        if (! xdrrec_endofrecord(xdrs, shipnow)) {
                release_fd_lock(elem, mask);
                return (ct->ct_error.re_status = RPC_CANTSEND);
        }
        if (! shipnow) {
                release_fd_lock(elem, mask);
                return (RPC_SUCCESS);
        }
        /*
         * Hack to provide rpc-based message passing
         */
        if (timeout.tv_sec == 0 && timeout.tv_usec == 0) {
                release_fd_lock(elem, mask);
                return(ct->ct_error.re_status = RPC_TIMEDOUT);
        }


        /*
         * Keep receiving until we get a valid transaction id
         */
        xdrs->x_op = XDR_DECODE;
        while (TRUE) {
                reply_msg.acpted_rply.ar_verf = _null_auth;
                reply_msg.acpted_rply.ar_results.where = NULL;
                reply_msg.acpted_rply.ar_results.proc = (xdrproc_t)xdr_void;
                if (! xdrrec_skiprecord(xdrs)) {
                        release_fd_lock(elem, mask);
                        return (ct->ct_error.re_status);
                }
                /* now decode and validate the response header */
                if (! xdr_replymsg(xdrs, &reply_msg)) {
                        if (ct->ct_error.re_status == RPC_SUCCESS)
                                continue;
                        release_fd_lock(elem, mask);
                        return (ct->ct_error.re_status);
                }
                if (reply_msg.rm_xid == x_id)
                        break;
        }

        /*
         * process header
         */
        _seterr_reply(&reply_msg, &(ct->ct_error));
        if (ct->ct_error.re_status == RPC_SUCCESS) {
                if (! AUTH_VALIDATE(cl->cl_auth,
                    &reply_msg.acpted_rply.ar_verf)) {
                        ct->ct_error.re_status = RPC_AUTHERROR;
                        ct->ct_error.re_why = AUTH_INVALIDRESP;
                } else {
                        if (cl->cl_auth->ah_cred.oa_flavor != RPCSEC_GSS) {
                                reply_stat = (*xdr_results)(xdrs, results_ptr);
                        } else {
                                reply_stat = __rpc_gss_unwrap(cl->cl_auth,
                                    xdrs, xdr_results, results_ptr);
                        }
                        if (! reply_stat) {
                                if (ct->ct_error.re_status == RPC_SUCCESS)
                                        ct->ct_error.re_status =
                                                RPC_CANTDECODERES;
                        }
                }
                /* free verifier ... */
                if (reply_msg.acpted_rply.ar_verf.oa_base != NULL) {
                        xdrs->x_op = XDR_FREE;
                        (void)xdr_opaque_auth(xdrs,
                            &(reply_msg.acpted_rply.ar_verf));
                }
        }  /* end successful completion */
        else {
                /* maybe our credentials need to be refreshed ... */
                if (refreshes-- && AUTH_REFRESH(cl->cl_auth, &reply_msg))
                        goto call_again;
        }  /* end of unsuccessful completion */
        release_fd_lock(elem, mask);
        return (ct->ct_error.re_status);
}

static void
clnt_vc_geterr(CLIENT *cl, struct rpc_err *errp)
{
        struct ct_data *ct;

        assert(cl != NULL);
        assert(errp != NULL);

        ct = (struct ct_data *) cl->cl_private;
        *errp = ct->ct_error;
}

static bool_t
clnt_vc_freeres(CLIENT *cl, xdrproc_t xdr_res, void *res_ptr)
{
        struct ct_data *ct;
        struct vc_fd *elem;
        XDR *xdrs;
        bool_t dummy;
        sigset_t mask;
        sigset_t newmask;

        assert(cl != NULL);

        ct = (struct ct_data *)cl->cl_private;
        xdrs = &(ct->ct_xdrs);

        sigfillset(&newmask);
        thr_sigsetmask(SIG_SETMASK, &newmask, &mask);
        mutex_lock(&clnt_fd_lock);
        elem = vc_fd_find(ct->ct_fd);
        mutex_lock(&elem->mtx);
        xdrs->x_op = XDR_FREE;
        dummy = (*xdr_res)(xdrs, res_ptr);

        mutex_unlock(&clnt_fd_lock);
        release_fd_lock(elem, mask);
        return dummy;
}

/*ARGSUSED*/
static void
clnt_vc_abort(CLIENT *cl)
{
}

static __inline void
htonlp(void *dst, const void *src, uint32_t incr)
{
        /* We are aligned, so we think */
        *(uint32_t *)dst = htonl(*(const uint32_t *)src + incr);
}

static __inline void
ntohlp(void *dst, const void *src)
{
        /* We are aligned, so we think */
        *(uint32_t *)dst = htonl(*(const uint32_t *)src);
}

static bool_t
clnt_vc_control(CLIENT *cl, u_int request, void *info)
{
        struct ct_data *ct;
        struct vc_fd *elem;
        void *infop = info;
        sigset_t mask;
        sigset_t newmask;

        assert(cl != NULL);

        ct = (struct ct_data *)cl->cl_private;

        sigfillset(&newmask);
        thr_sigsetmask(SIG_SETMASK, &newmask, &mask);
        mutex_lock(&clnt_fd_lock);
        elem = vc_fd_find(ct->ct_fd);
        mutex_unlock(&clnt_fd_lock);
        mutex_lock(&elem->mtx);

        switch (request) {
        case CLSET_FD_CLOSE:
                ct->ct_closeit = TRUE;
                release_fd_lock(elem, mask);
                return (TRUE);
        case CLSET_FD_NCLOSE:
                ct->ct_closeit = FALSE;
                release_fd_lock(elem, mask);
                return (TRUE);
        default:
                break;
        }

        /* for other requests which use info */
        if (info == NULL) {
                release_fd_lock(elem, mask);
                return (FALSE);
        }
        switch (request) {
        case CLSET_TIMEOUT:
                if (time_not_ok((struct timeval *)info)) {
                        release_fd_lock(elem, mask);
                        return (FALSE);
                }
                ct->ct_wait = *(struct timeval *)infop;
                ct->ct_waitset = TRUE;
                break;
        case CLGET_TIMEOUT:
                *(struct timeval *)infop = ct->ct_wait;
                break;
        case CLGET_SERVER_ADDR:
                (void) memcpy(info, ct->ct_addr.buf, (size_t)ct->ct_addr.len);
                break;
        case CLGET_FD:
                *(int *)info = ct->ct_fd;
                break;
        case CLGET_SVC_ADDR:
                /* The caller should not free this memory area */
                *(struct netbuf *)info = ct->ct_addr;
                break;
        case CLSET_SVC_ADDR:            /* set to new address */
                release_fd_lock(elem, mask);
                return (FALSE);
        case CLGET_XID:
                /*
                 * use the knowledge that xid is the
                 * first element in the call structure
                 * This will get the xid of the PREVIOUS call
                 */
                ntohlp(info, &ct->ct_u.ct_mcalli);
                break;
        case CLSET_XID:
                /* This will set the xid of the NEXT call */
                /* increment by 1 as clnt_vc_call() decrements once */
                htonlp(&ct->ct_u.ct_mcalli, info, 1);
                break;
        case CLGET_VERS:
                /*
                 * This RELIES on the information that, in the call body,
                 * the version number field is the fifth field from the
                 * beginning of the RPC header. MUST be changed if the
                 * call_struct is changed
                 */
                ntohlp(info, ct->ct_u.ct_mcallc + 4 * BYTES_PER_XDR_UNIT);
                break;

        case CLSET_VERS:
                htonlp(ct->ct_u.ct_mcallc + 4 * BYTES_PER_XDR_UNIT, info, 0);
                break;

        case CLGET_PROG:
                /*
                 * This RELIES on the information that, in the call body,
                 * the program number field is the fourth field from the
                 * beginning of the RPC header. MUST be changed if the
                 * call_struct is changed
                 */
                ntohlp(info, ct->ct_u.ct_mcallc + 3 * BYTES_PER_XDR_UNIT);
                break;

        case CLSET_PROG:
                htonlp(ct->ct_u.ct_mcallc + 3 * BYTES_PER_XDR_UNIT, info, 0);
                break;

        default:
                release_fd_lock(elem, mask);
                return (FALSE);
        }
        release_fd_lock(elem, mask);
        return (TRUE);
}


static void
clnt_vc_destroy(CLIENT *cl)
{
        struct ct_data *ct = (struct ct_data *) cl->cl_private;
        struct vc_fd *elem;
        int ct_fd = ct->ct_fd;
        sigset_t mask;
        sigset_t newmask;

        assert(cl != NULL);

        ct = (struct ct_data *) cl->cl_private;

        sigfillset(&newmask);
        thr_sigsetmask(SIG_SETMASK, &newmask, &mask);
        mutex_lock(&clnt_fd_lock);
        elem = vc_fd_find(ct_fd);
        mutex_lock(&elem->mtx);
        if (ct->ct_closeit && ct->ct_fd != -1) {
                (void)_close(ct->ct_fd);
        }
        XDR_DESTROY(&(ct->ct_xdrs));
        free(ct->ct_addr.buf);
        mem_free(ct, sizeof(struct ct_data));
        if (cl->cl_netid && cl->cl_netid[0])
                mem_free(cl->cl_netid, strlen(cl->cl_netid) +1);
        if (cl->cl_tp && cl->cl_tp[0])
                mem_free(cl->cl_tp, strlen(cl->cl_tp) +1);
        mem_free(cl, sizeof(CLIENT));
        mutex_unlock(&clnt_fd_lock);
        release_fd_lock(elem, mask);
}

/*
 * Interface between xdr serializer and tcp connection.
 * Behaves like the system calls, read & write, but keeps some error state
 * around for the rpc level.
 */
static int
read_vc(void *ctp, void *buf, int len)
{
        struct sockaddr sa;
        socklen_t sal;
        struct ct_data *ct = (struct ct_data *)ctp;
        struct pollfd fd;
        int milliseconds = (int)((ct->ct_wait.tv_sec * 1000) +
            (ct->ct_wait.tv_usec / 1000));

        if (len == 0)
                return (0);
        fd.fd = ct->ct_fd;
        fd.events = POLLIN;
        for (;;) {
                switch (_poll(&fd, 1, milliseconds)) {
                case 0:
                        ct->ct_error.re_status = RPC_TIMEDOUT;
                        return (-1);

                case -1:
                        if (errno == EINTR)
                                continue;
                        ct->ct_error.re_status = RPC_CANTRECV;
                        ct->ct_error.re_errno = errno;
                        return (-1);
                }
                break;
        }

        sal = sizeof(sa);
        if ((_getpeername(ct->ct_fd, &sa, &sal) == 0) &&
            (sa.sa_family == AF_LOCAL)) {
                len = __msgread(ct->ct_fd, buf, (size_t)len);
        } else {
                len = _read(ct->ct_fd, buf, (size_t)len);
        }

        switch (len) {
        case 0:
                /* premature eof */
                ct->ct_error.re_errno = ECONNRESET;
                ct->ct_error.re_status = RPC_CANTRECV;
                len = -1;  /* it's really an error */
                break;

        case -1:
                ct->ct_error.re_errno = errno;
                ct->ct_error.re_status = RPC_CANTRECV;
                break;
        }
        return (len);
}

static int
write_vc(void *ctp, void *buf, int len)
{
        struct sockaddr sa;
        socklen_t sal;
        struct ct_data *ct = (struct ct_data *)ctp;
        int i, cnt;

        sal = sizeof(sa);
        if ((_getpeername(ct->ct_fd, &sa, &sal) == 0) &&
            (sa.sa_family == AF_LOCAL)) {
                for (cnt = len; cnt > 0; cnt -= i, buf = (char *)buf + i) {
                        if ((i = __msgwrite(ct->ct_fd, buf,
                             (size_t)cnt)) == -1) {
                                ct->ct_error.re_errno = errno;
                                ct->ct_error.re_status = RPC_CANTSEND;
                                return (-1);
                        }
                }
        } else {
                for (cnt = len; cnt > 0; cnt -= i, buf = (char *)buf + i) {
                        if ((i = _write(ct->ct_fd, buf, (size_t)cnt)) == -1) {
                                ct->ct_error.re_errno = errno;
                                ct->ct_error.re_status = RPC_CANTSEND;
                                return (-1);
                        }
                }
        }
        return (len);
}

static struct clnt_ops *
clnt_vc_ops(void)
{
        static struct clnt_ops ops;
        sigset_t mask, newmask;

        /* VARIABLES PROTECTED BY ops_lock: ops */

        sigfillset(&newmask);
        thr_sigsetmask(SIG_SETMASK, &newmask, &mask);
        mutex_lock(&ops_lock);
        if (ops.cl_call == NULL) {
                ops.cl_call = clnt_vc_call;
                ops.cl_abort = clnt_vc_abort;
                ops.cl_geterr = clnt_vc_geterr;
                ops.cl_freeres = clnt_vc_freeres;
                ops.cl_destroy = clnt_vc_destroy;
                ops.cl_control = clnt_vc_control;
        }
        mutex_unlock(&ops_lock);
        thr_sigsetmask(SIG_SETMASK, &(mask), NULL);
        return (&ops);
}

/*
 * Make sure that the time is not garbage.   -1 value is disallowed.
 * Note this is different from time_not_ok in clnt_dg.c
 */
static bool_t
time_not_ok(struct timeval *t)
{
        return (t->tv_sec <= -1 || t->tv_sec > 100000000 ||
                t->tv_usec <= -1 || t->tv_usec > 1000000);
}

static int
__msgread(int sock, void *buf, size_t cnt)
{
        struct iovec iov[1];
        struct msghdr msg;
        union {
                struct cmsghdr cmsg;
                char control[CMSG_SPACE(sizeof(struct cmsgcred))];
        } cm;
 
        bzero((char *)&cm, sizeof(cm));
        iov[0].iov_base = buf;
        iov[0].iov_len = cnt;
 
        msg.msg_iov = iov;
        msg.msg_iovlen = 1;
        msg.msg_name = NULL;
        msg.msg_namelen = 0;
        msg.msg_control = (caddr_t)&cm;
        msg.msg_controllen = CMSG_SPACE(sizeof(struct cmsgcred));
        msg.msg_flags = 0;
 
        return(_recvmsg(sock, &msg, 0));
}

static int
__msgwrite(int sock, void *buf, size_t cnt)
{
        struct iovec iov[1];
        struct msghdr msg;
        union {
                struct cmsghdr cmsg;
                char control[CMSG_SPACE(sizeof(struct cmsgcred))];
        } cm;
 
        bzero((char *)&cm, sizeof(cm));
        iov[0].iov_base = buf;
        iov[0].iov_len = cnt;
 
        cm.cmsg.cmsg_type = SCM_CREDS;
        cm.cmsg.cmsg_level = SOL_SOCKET;
        cm.cmsg.cmsg_len = CMSG_LEN(sizeof(struct cmsgcred));
 
        msg.msg_iov = iov;
        msg.msg_iovlen = 1;
        msg.msg_name = NULL;
        msg.msg_namelen = 0;
        msg.msg_control = (caddr_t)&cm;
        msg.msg_controllen = CMSG_SPACE(sizeof(struct cmsgcred));
        msg.msg_flags = 0;

        return(_sendmsg(sock, &msg, 0));
}