/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2008 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/queue.h>
#include <rpc/rpc.h>
#include <rpc/rpcsec_gss.h>

#include "rpcsec_gss_int.h"

#ifndef _PATH_GSS_MECH
#define _PATH_GSS_MECH  "/etc/gss/mech"
#endif

#ifndef _PATH_GSS_QOP
#define _PATH_GSS_QOP   "/etc/gss/qop"
#endif

struct mech_info {
        SLIST_ENTRY(mech_info) link;
        char            *name;
        gss_OID_desc    oid;
        const char      **qops;
        char            *lib;
        char            *kobj;
};
SLIST_HEAD(mech_info_list, mech_info);

static struct mech_info_list mechs = SLIST_HEAD_INITIALIZER(mechs);
static const char **mech_names;

struct qop_info {
        SLIST_ENTRY(qop_info) link;
        char            *name;
        char*           mech;
        u_int           qop;
};
SLIST_HEAD(qop_info_list, qop_info);

static struct qop_info_list qops = SLIST_HEAD_INITIALIZER(qops);

static int
_rpc_gss_string_to_oid(const char* s, gss_OID oid)
{
        int                     number_count, i, j;
        int                     byte_count;
        const char              *p, *q;
        char                    *res;

        /*
         * First figure out how many numbers in the oid, then
         * calculate the compiled oid size.
         */
        number_count = 0;
        for (p = s; p; p = q) {
                q = strchr(p, '.');
                if (q) q = q + 1;
                number_count++;
        }
        
        /*
         * The first two numbers are in the first byte and each
         * subsequent number is encoded in a variable byte sequence.
         */
        if (number_count < 2)
                return (EINVAL);

        /*
         * We do this in two passes. The first pass, we just figure
         * out the size. Second time around, we actually encode the
         * number.
         */
        res = 0;
        for (i = 0; i < 2; i++) {
                byte_count = 0;
                for (p = s, j = 0; p; p = q, j++) {
                        u_int number = 0;

                        /*
                         * Find the end of this number.
                         */
                        q = strchr(p, '.');
                        if (q) q = q + 1;

                        /*
                         * Read the number of of the string. Don't
                         * bother with anything except base ten.
                         */
                        while (*p && *p != '.') {
                                number = 10 * number + (*p - '0');
                                p++;
                        }

                        /*
                         * Encode the number. The first two numbers
                         * are packed into the first byte. Subsequent
                         * numbers are encoded in bytes seven bits at
                         * a time with the last byte having the high
                         * bit set.
                         */
                        if (j == 0) {
                                if (res)
                                        *res = number * 40;
                        } else if (j == 1) {
                                if (res) {
                                        *res += number;
                                        res++;
                                }
                                byte_count++;
                        } else if (j >= 2) {
                                /*
                                 * The number is encoded in seven bit chunks.
                                 */
                                u_int t;
                                int bytes;

                                bytes = 0;
                                for (t = number; t; t >>= 7)
                                        bytes++;
                                if (bytes == 0) bytes = 1;
                                while (bytes) {
                                        if (res) {
                                                int bit = 7*(bytes-1);
                                                
                                                *res = (number >> bit) & 0x7f;
                                                if (bytes != 1)
                                                        *res |= 0x80;
                                                res++;
                                        }
                                        byte_count++;
                                        bytes--;
                                }
                        }
                }
                if (!res) {
                        res = malloc(byte_count);
                        if (!res)
                                return (ENOMEM);
                        oid->length = byte_count;
                        oid->elements = res;
                }
        }

        return (0);
}

static void
_rpc_gss_load_mech(void)
{
        FILE            *fp;
        char            buf[256];
        char            *p;
        char            *name, *oid, *lib, *kobj;
        struct mech_info *info;
        int             count;
        const char      **pp;

        if (SLIST_FIRST(&mechs))
                return;

        fp = fopen(_PATH_GSS_MECH, "r");
        if (!fp)
                return;

        count = 0;
        while (fgets(buf, sizeof(buf), fp)) {
                if (*buf == '#')
                        continue;
                p = buf;
                name = strsep(&p, "\t\n ");
                if (p) while (isspace(*p)) p++;
                oid = strsep(&p, "\t\n ");
                if (p) while (isspace(*p)) p++;
                lib = strsep(&p, "\t\n ");
                if (p) while (isspace(*p)) p++;
                kobj = strsep(&p, "\t\n ");
                if (!name || !oid || !lib || !kobj)
                        continue;

                info = malloc(sizeof(struct mech_info));
                if (!info)
                        break;
                if (_rpc_gss_string_to_oid(oid, &info->oid)) {
                        free(info);
                        continue;
                }
                info->name = strdup(name);
                info->qops = NULL;
                info->lib = strdup(lib);
                info->kobj = strdup(kobj);
                SLIST_INSERT_HEAD(&mechs, info, link);
                count++;
        }
        fclose(fp);

        mech_names = malloc((count + 1) * sizeof(char*));
        pp = mech_names;
        SLIST_FOREACH(info, &mechs, link) {
                *pp++ = info->name;
        }
        *pp = NULL;
}

static void
_rpc_gss_load_qop(void)
{
        FILE            *fp;
        char            buf[256];
        char            *p;
        char            *name, *num, *mech;
        struct mech_info *minfo;
        struct qop_info *info;
        int             count;
        const char      **mech_qops;
        const char      **pp;

        if (SLIST_FIRST(&qops))
                return;

        fp = fopen(_PATH_GSS_QOP, "r");
        if (!fp)
                return;

        while (fgets(buf, sizeof(buf), fp)) {
                if (*buf == '#')
                        continue;
                p = buf;
                name = strsep(&p, "\t\n ");
                if (p) while (isspace(*p)) p++;
                num = strsep(&p, "\t\n ");
                if (p) while (isspace(*p)) p++;
                mech = strsep(&p, "\t\n ");
                if (!name || !num || !mech)
                        continue;

                info = malloc(sizeof(struct qop_info));
                if (!info)
                        break;
                info->name = strdup(name);
                info->qop = strtoul(name, 0, 0);
                info->mech = strdup(mech);
                SLIST_INSERT_HEAD(&qops, info, link);
        }
        fclose(fp);

        /*
         * Compile lists of qops for each mechanism.
         */
        SLIST_FOREACH(minfo, &mechs, link) {
                count = 0;
                SLIST_FOREACH(info, &qops, link) {
                        if (strcmp(info->mech, minfo->name) == 0)
                                count++;
                }
                mech_qops = malloc((count + 1) * sizeof(char*));
                pp = mech_qops;
                SLIST_FOREACH(info, &qops, link) {
                        if (strcmp(info->mech, minfo->name) == 0)
                                *pp++ = info->name;
                }
                *pp = NULL;
                minfo->qops = mech_qops;
        }
}

bool_t
rpc_gss_mech_to_oid(const char *mech, gss_OID *oid_ret)
{
        struct mech_info *info;

        _rpc_gss_load_mech();
        SLIST_FOREACH(info, &mechs, link) {
                if (!strcmp(info->name, mech)) {
                        *oid_ret = &info->oid;
                        return (TRUE);
                }
        }
        _rpc_gss_set_error(RPC_GSS_ER_SYSTEMERROR, ENOENT);
        return (FALSE);
}

bool_t
rpc_gss_oid_to_mech(gss_OID oid, const char **mech_ret)
{
        struct mech_info *info;

        _rpc_gss_load_mech();
        SLIST_FOREACH(info, &mechs, link) {
                if (oid->length == info->oid.length
                    && !memcmp(oid->elements, info->oid.elements,
                        oid->length)) {
                        *mech_ret = info->name;
                        return (TRUE);
                }
        }
        _rpc_gss_set_error(RPC_GSS_ER_SYSTEMERROR, ENOENT);
        return (FALSE);
}

bool_t
rpc_gss_qop_to_num(const char *qop, const char *mech, u_int *num_ret)
{
        struct qop_info *info;

        _rpc_gss_load_qop();
        SLIST_FOREACH(info, &qops, link) {
                if (strcmp(info->name, qop) == 0
                    && strcmp(info->mech, mech) == 0) {
                        *num_ret = info->qop;
                        return (TRUE);
                }
        }
        _rpc_gss_set_error(RPC_GSS_ER_SYSTEMERROR, ENOENT);
        return (FALSE);
}

const char *
_rpc_gss_num_to_qop(const char *mech, u_int num)
{
        struct qop_info *info;

        if (num == GSS_C_QOP_DEFAULT)
                return "default";

        _rpc_gss_load_qop();
        SLIST_FOREACH(info, &qops, link) {
                if (info->qop == num && strcmp(info->mech, mech) == 0) {
                        return (info->name);
                }
        }
        return (NULL);
}

const char **
rpc_gss_get_mechanisms(void)
{

        _rpc_gss_load_mech();
        return (mech_names);
}

const char **
rpc_gss_get_mech_info(const char *mech, rpc_gss_service_t *service)
{
        struct mech_info *info;

        _rpc_gss_load_mech();
        _rpc_gss_load_qop();
        SLIST_FOREACH(info, &mechs, link) {
                if (!strcmp(mech, info->name)) {
                        /*
                         * I'm not sure what to do with service
                         * here. The Solaris manpages are not clear on
                         * the subject and the OpenSolaris code just
                         * sets it to rpc_gss_svc_privacy
                         * unconditionally with a comment noting that
                         * it is bogus.
                         */
                        *service = rpc_gss_svc_privacy;
                        return info->qops;
                }
        }

        _rpc_gss_set_error(RPC_GSS_ER_SYSTEMERROR, ENOENT);
        return (NULL);
}

bool_t
rpc_gss_get_versions(u_int *vers_hi, u_int *vers_lo)
{

        *vers_hi = 1;
        *vers_lo = 1;
        return (TRUE);
}

bool_t
rpc_gss_is_installed(const char *mech)
{
        struct mech_info *info;

        _rpc_gss_load_mech();
        SLIST_FOREACH(info, &mechs, link)
                if (!strcmp(mech, info->name))
                        return (TRUE);
        return (FALSE);
}