librpcsvc/common/bindresvport.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
 */

/*  Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*
 * XXX This routine should be changed to use
 * ND_CHECK_RESERVED_PORT and ND_SET_RESERVED_PORT
 * which can be invoked via netdir_options.
 */
#include <stdio.h>
#include <rpc/rpc.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>
#include <errno.h>
#include <rpc/nettype.h>
#include <stropts.h>
#include <string.h>
#include <tiuser.h>
#include <unistd.h>

#define STARTPORT 600
#define ENDPORT (IPPORT_RESERVED - 1)
#define NPORTS  (ENDPORT - STARTPORT + 1)

/*
 * The argument is a client handle for a UDP connection.
 * Unbind its transport endpoint from the existing port
 * and rebind it to a reserved port.
 * On failure, the client handle can be unbound even if it
 * was previously bound.  Callers should destroy the client
 * handle after a failure.
 */
int
__clnt_bindresvport(cl)
    CLIENT *cl;
{
    int fd;
    int res;
    short port;
    struct sockaddr_in *sin;
    struct sockaddr_in6 *sin6;
    extern int errno;
    /* extern int t_errno; */
    struct t_bind *tbind, *tres;
    int i;
    bool_t  ipv6_fl = FALSE;
    struct netconfig *nconf;

    /* make sure it's a UDP connection */
    nconf = getnetconfigent(cl->cl_netid);
    if (nconf == NULL)
        return (-1);
    if ((nconf->nc_semantics != NC_TPI_CLTS) ||
        (strcmp(nconf->nc_protofmly, NC_INET) &&
        strcmp(nconf->nc_protofmly, NC_INET6)) ||
        strcmp(nconf->nc_proto, NC_UDP)) {
        freenetconfigent(nconf);
        return (0); /* not udp - don't need resv port */
    }
    if (strcmp(nconf->nc_protofmly, NC_INET6) == 0)
        ipv6_fl = TRUE;
    freenetconfigent(nconf);

    if (!clnt_control(cl, CLGET_FD, (char *)&fd)) {
        return (-1);
    }

    /* If fd is already bound - unbind it */
    if (t_getstate(fd) != T_UNBND) {
        while ((t_unbind(fd) < 0) && (t_errno == TLOOK)) {
            /*
             * If there is a message queued to this descriptor,
             * remove it.
             */
            struct strbuf ctl[1], data[1];
            char ctlbuf[sizeof (union T_primitives) + 32];
            char databuf[256];
            int flags;

            ctl->maxlen = sizeof (ctlbuf);
            ctl->buf = ctlbuf;
            data->maxlen = sizeof (databuf);
            data->buf = databuf;
            flags = 0;
            if (getmsg(fd, ctl, data, &flags) < 0)
                return (-1);

        }
        if (t_getstate(fd) != T_UNBND)
            return (-1);
    }

    tbind = (struct t_bind *)t_alloc(fd, T_BIND, T_ADDR);
    if (tbind == NULL) {
        if (t_errno == TBADF)
            errno = EBADF;
        return (-1);
    }
    tres = (struct t_bind *)t_alloc(fd, T_BIND, T_ADDR);
    if (tres == NULL) {
        (void) t_free((char *)tbind, T_BIND);
        return (-1);
    }

    (void) memset((char *)tbind->addr.buf, 0, tbind->addr.len);
    /* warning: this sockaddr_in is truncated to 8 bytes */

    if (ipv6_fl == TRUE) {
        sin6 = (struct sockaddr_in6 *)tbind->addr.buf;
        sin6->sin6_family = AF_INET6;
    } else {
        sin = (struct sockaddr_in *)tbind->addr.buf;
        sin->sin_family = AF_INET;
    }

    tbind->qlen = 0;
    tbind->addr.len = tbind->addr.maxlen;

    /*
     * Need to find a reserved port in the interval
     * STARTPORT - ENDPORT.  Choose a random starting
     * place in the interval based on the process pid
     * and sequentially search the ports for one
     * that is available.
     */
    port = (getpid() % NPORTS) + STARTPORT;

    for (i = 0; i < NPORTS; i++) {
        if (ipv6_fl == TRUE)
            sin6->sin6_port = htons(port++);
        else
            sin->sin_port = htons(port++);
        if (port > ENDPORT)
            port = STARTPORT;
        /*
         * Try to bind to the requested address.  If
         * the call to t_bind succeeds, then we need
         * to make sure that the address that we bound
         * to was the address that we requested.  If it
         * was, then we are done.  If not, we fake an
         * EADDRINUSE error by setting res, t_errno,
         * and errno to indicate that a bind failure
         * occurred.  Otherwise, if the t_bind call
         * failed, we check to see whether it makes
         * sense to continue trying to t_bind requests.
         */
        res = t_bind(fd, tbind, tres);
        if (res == 0) {
            if (memcmp(tbind->addr.buf, tres->addr.buf,
                    (int)tres->addr.len) == 0)
                break;
            (void) t_unbind(fd);
            res = -1;
            t_errno = TSYSERR;
            errno = EADDRINUSE;
        } else if (t_errno != TSYSERR || errno != EADDRINUSE) {
            if (t_errno == TACCES)
                errno = EACCES;
            break;
        }
    }

    (void) t_free((char *)tbind, T_BIND);
    (void) t_free((char *)tres,  T_BIND);
    return (res);
}