/*
 * 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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * This module reads and writes the stable identifier values, DUID and IAID.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <limits.h>
#include <fcntl.h>
#include <errno.h>
#include <libdlpi.h>
#include <uuid/uuid.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <net/if.h>
#include <netinet/dhcp6.h>
#include <dhcp_inittab.h>

#define DUID_FILE       "/etc/dhcp/duid"
#define IAID_FILE       "/etc/dhcp/iaid"

struct iaid_ent {
        uint32_t        ie_iaid;
        char            ie_name[LIFNAMSIZ];
};

/*
 * read_stable_duid(): read the system's stable DUID, if any
 *
 *   input: size_t *: pointer to a size_t to return the DUID length
 *  output: uchar_t *: the DUID buffer, or NULL on error (and errno is set)
 *    note: memory returned is from malloc; caller must free.
 */

uchar_t *
read_stable_duid(size_t *duidlen)
{
        int fd;
        ssize_t retv;
        struct stat sb;
        uchar_t *duid = NULL;

        if ((fd = open(DUID_FILE, O_RDONLY)) == -1)
                return (NULL);
        if (fstat(fd, &sb) != -1 && S_ISREG(sb.st_mode) &&
            (duid = malloc(sb.st_size)) != NULL) {
                retv = read(fd, duid, sb.st_size);
                if (retv == sb.st_size) {
                        *duidlen = sb.st_size;
                } else {
                        free(duid);
                        /*
                         * Make sure that errno always gets set when something
                         * goes wrong.
                         */
                        if (retv >= 0)
                                errno = EINVAL;
                        duid = NULL;
                }
        }
        (void) close(fd);
        return (duid);
}

/*
 * write_stable_duid(): write the system's stable DUID.
 *
 *   input: const uchar_t *: pointer to the DUID buffer
 *          size_t: length of the DUID
 *  output: int: 0 on success, -1 on error.  errno is set on error.
 */

int
write_stable_duid(const uchar_t *duid, size_t duidlen)
{
        int fd;
        ssize_t retv;

        (void) unlink(DUID_FILE);
        if ((fd = open(DUID_FILE, O_WRONLY | O_CREAT, 0644)) == -1)
                return (-1);
        retv = write(fd, duid, duidlen);
        if (retv == duidlen) {
                return (close(fd));
        } else {
                (void) close(fd);
                if (retv >= 0)
                        errno = ENOSPC;
                return (-1);
        }
}

/*
 * make_stable_duid(): create a new DUID
 *
 *   input: const char *: name of physical interface for reference
 *          size_t *: pointer to a size_t to return the DUID length
 *  output: uchar_t *: the DUID buffer, or NULL on error (and errno is set)
 *    note: memory returned is from malloc; caller must free.
 */

uchar_t *
make_stable_duid(const char *physintf, size_t *duidlen)
{
        int len;
        dlpi_info_t dlinfo;
        dlpi_handle_t dh = NULL;
        uint_t arptype;
        duid_en_t *den;

        /*
         * Try to read the MAC layer address for the physical interface
         * provided as a hint.  If that works, we can use a DUID-LLT.
         */

        if (dlpi_open(physintf, &dh, 0) == DLPI_SUCCESS &&
            dlpi_bind(dh, DLPI_ANY_SAP, NULL) == DLPI_SUCCESS &&
            dlpi_info(dh, &dlinfo, 0) == DLPI_SUCCESS &&
            (len = dlinfo.di_physaddrlen) > 0 &&
            (arptype = dlpi_arptype(dlinfo.di_mactype) != 0)) {
                duid_llt_t *dllt;
                time_t now;

                if ((dllt = malloc(sizeof (*dllt) + len)) == NULL) {
                        dlpi_close(dh);
                        return (NULL);
                }

                (void) memcpy((dllt + 1), dlinfo.di_physaddr, len);
                dllt->dllt_dutype = htons(DHCPV6_DUID_LLT);
                dllt->dllt_hwtype = htons(arptype);
                now = time(NULL) - DUID_TIME_BASE;
                dllt->dllt_time = htonl(now);
                *duidlen = sizeof (*dllt) + len;
                dlpi_close(dh);
                return ((uchar_t *)dllt);
        }
        if (dh != NULL)
                dlpi_close(dh);

        /*
         * If we weren't able to create a DUID based on the network interface
         * in use, then generate one based on a UUID.
         */
        den = malloc(sizeof (*den) + UUID_LEN);
        if (den != NULL) {
                uuid_t uuid;

                den->den_dutype = htons(DHCPV6_DUID_EN);
                DHCPV6_SET_ENTNUM(den, DHCPV6_SUN_ENT);
                uuid_generate(uuid);
                (void) memcpy(den + 1, uuid, UUID_LEN);
                *duidlen = sizeof (*den) + UUID_LEN;
        }
        return ((uchar_t *)den);
}

/*
 * read_stable_iaid(): read a link's stable IAID, if any
 *
 *   input: const char *: interface name
 *  output: uint32_t: the IAID, or 0 if none
 */

uint32_t
read_stable_iaid(const char *intf)
{
        int fd;
        struct iaid_ent ie;

        if ((fd = open(IAID_FILE, O_RDONLY)) == -1)
                return (0);
        while (read(fd, &ie, sizeof (ie)) == sizeof (ie)) {
                if (strcmp(intf, ie.ie_name) == 0) {
                        (void) close(fd);
                        return (ie.ie_iaid);
                }
        }
        (void) close(fd);
        return (0);
}

/*
 * write_stable_iaid(): write out a link's stable IAID
 *
 *   input: const char *: interface name
 *  output: uint32_t: the IAID, or 0 if none
 */

int
write_stable_iaid(const char *intf, uint32_t iaid)
{
        int fd;
        struct iaid_ent ie;
        ssize_t retv;

        if ((fd = open(IAID_FILE, O_RDWR | O_CREAT, 0644)) == -1)
                return (0);
        while (read(fd, &ie, sizeof (ie)) == sizeof (ie)) {
                if (strcmp(intf, ie.ie_name) == 0) {
                        (void) close(fd);
                        if (iaid == ie.ie_iaid) {
                                return (0);
                        } else {
                                errno = EINVAL;
                                return (-1);
                        }
                }
        }
        (void) memset(&ie, 0, sizeof (ie));
        ie.ie_iaid = iaid;
        (void) strlcpy(ie.ie_name, intf, sizeof (ie.ie_name));
        retv = write(fd, &ie, sizeof (ie));
        (void) close(fd);
        if (retv == sizeof (ie)) {
                return (0);
        } else {
                if (retv >= 0)
                        errno = ENOSPC;
                return (-1);
        }
}

/*
 * make_stable_iaid(): create a stable IAID for a link
 *
 *   input: const char *: interface name
 *          uint32_t: the ifIndex for this link (as a "hint")
 *  output: uint32_t: the new IAID, never zero
 */

/* ARGSUSED */
uint32_t
make_stable_iaid(const char *intf, uint32_t hint)
{
        int fd;
        struct iaid_ent ie;
        uint32_t maxid, minunused;
        boolean_t recheck;

        if ((fd = open(IAID_FILE, O_RDONLY)) == -1)
                return (hint);
        maxid = 0;
        minunused = 1;
        /*
         * This logic is deliberately unoptimized.  The reason is that it runs
         * essentially just once per interface for the life of the system.
         * Once the IAID is established, there's no reason to generate it
         * again, and all we care about here is correctness.  Also, IAIDs tend
         * to get added in a logical sequence order, so the outer loop should
         * not normally run more than twice.
         */
        do {
                recheck = B_FALSE;
                while (read(fd, &ie, sizeof (ie)) == sizeof (ie)) {
                        if (ie.ie_iaid > maxid)
                                maxid = ie.ie_iaid;
                        if (ie.ie_iaid == minunused) {
                                recheck = B_TRUE;
                                minunused++;
                        }
                        if (ie.ie_iaid == hint)
                                hint = 0;
                }
                if (recheck)
                        (void) lseek(fd, 0, SEEK_SET);
        } while (recheck);
        (void) close(fd);
        if (hint != 0)
                return (hint);
        else if (maxid != UINT32_MAX)
                return (maxid + 1);
        else
                return (minunused);
}