/*
 * Copyright (c) 2000 - 2002, 2004 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * 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.
 *
 * 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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 "krb5_locl.h"
#include <fnmatch.h>

struct acl_field {
    enum { acl_string, acl_fnmatch, acl_retval } type;
    union {
        const char *cstr;
        char **retv;
    } u;
    struct acl_field *next, **last;
};

static void
free_retv(struct acl_field *acl)
{
    while(acl != NULL) {
        if (acl->type == acl_retval) {
            if (*acl->u.retv)
                free(*acl->u.retv);
            *acl->u.retv = NULL;
        }
        acl = acl->next;
    }
}

static void
acl_free_list(struct acl_field *acl, int retv)
{
    struct acl_field *next;
    if (retv)
        free_retv(acl);
    while(acl != NULL) {
        next = acl->next;
        free(acl);
        acl = next;
    }
}

static krb5_error_code
acl_parse_format(krb5_context context,
                 struct acl_field **acl_ret,
                 const char *format,
                 va_list ap)
{
    const char *p;
    struct acl_field *acl = NULL, *tmp;

    for(p = format; *p != '\0'; p++) {
        tmp = malloc(sizeof(*tmp));
        if(tmp == NULL) {
            krb5_set_error_message(context, ENOMEM,
                                   N_("malloc: out of memory", ""));
            acl_free_list(acl, 0);
            return ENOMEM;
        }
        if(*p == 's') {
            tmp->type = acl_string;
            tmp->u.cstr = va_arg(ap, const char*);
        } else if(*p == 'f') {
            tmp->type = acl_fnmatch;
            tmp->u.cstr = va_arg(ap, const char*);
        } else if(*p == 'r') {
            tmp->type = acl_retval;
            tmp->u.retv = va_arg(ap, char **);
            *tmp->u.retv = NULL;
        } else {
            krb5_set_error_message(context, EINVAL,
                                   N_("Unknown format specifier %c while "
                                     "parsing ACL", "specifier"), *p);
            acl_free_list(acl, 0);
            free(tmp);
            return EINVAL;
        }
        tmp->next = NULL;
        if(acl == NULL)
            acl = tmp;
        else
            *acl->last = tmp;
        acl->last = &tmp->next;
    }
    *acl_ret = acl;
    return 0;
}

static krb5_boolean
acl_match_field(krb5_context context,
                const char *string,
                struct acl_field *field)
{
    if(field->type == acl_string) {
        return !strcmp(field->u.cstr, string);
    } else if(field->type == acl_fnmatch) {
        return !fnmatch(field->u.cstr, string, 0);
    } else if(field->type == acl_retval) {
        *field->u.retv = strdup(string);
        return TRUE;
    }
    return FALSE;
}

static krb5_boolean
acl_match_acl(krb5_context context,
              struct acl_field *acl,
              const char *string)
{
    char buf[256];
    while(strsep_copy(&string, " \t", buf, sizeof(buf)) != -1) {
        if(buf[0] == '\0')
            continue; /* skip ws */
        if (acl == NULL)
            return FALSE;
        if(!acl_match_field(context, buf, acl)) {
            return FALSE;
        }
        acl = acl->next;
    }
    if (acl)
        return FALSE;
    return TRUE;
}

/**
 * krb5_acl_match_string matches ACL format against a string.
 *
 * The ACL format has three format specifiers: s, f, and r.  Each
 * specifier will retrieve one argument from the variable arguments
 * for either matching or storing data.  The input string is split up
 * using " " (space) and "\t" (tab) as a delimiter; multiple and "\t"
 * in a row are considered to be the same.
 *
 * List of format specifiers:
 * - s Matches a string using strcmp(3) (case sensitive).
 * - f Matches the string with fnmatch(3). Theflags
 *     argument (the last argument) passed to the fnmatch function is 0.
 * - r Returns a copy of the string in the char ** passed in; the copy
 *     must be freed with free(3). There is no need to free(3) the
 *     string on error: the function will clean up and set the pointer
 *     to NULL.
 *
 * @param context Kerberos 5 context
 * @param string string to match with
 * @param format format to match
 * @param ... parameter to format string
 *
 * @return Return an error code or 0.
 *
 *
 * @code
 * char *s;
 *
 * ret = krb5_acl_match_string(context, "foo", "s", "foo");
 * if (ret)
 *     krb5_errx(context, 1, "acl didn't match");
 * ret = krb5_acl_match_string(context, "foo foo baz/kaka",
 *     "ss", "foo", &s, "foo/\\*");
 * if (ret) {
 *     // no need to free(s) on error
 *     assert(s == NULL);
 *     krb5_errx(context, 1, "acl didn't match");
 * }
 * free(s);
 * @endcode
 *
 * @sa krb5_acl_match_file
 * @ingroup krb5_support
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_acl_match_string(krb5_context context,
                      const char *string,
                      const char *format,
                      ...)
{
    krb5_error_code ret;
    krb5_boolean found;
    struct acl_field *acl;

    va_list ap;
    va_start(ap, format);
    ret = acl_parse_format(context, &acl, format, ap);
    va_end(ap);
    if(ret)
        return ret;

    found = acl_match_acl(context, acl, string);
    acl_free_list(acl, !found);
    if (found) {
        return 0;
    } else {
        krb5_set_error_message(context, EACCES, N_("ACL did not match", ""));
        return EACCES;
    }
}

/**
 * krb5_acl_match_file matches ACL format against each line in a file
 * using krb5_acl_match_string(). Lines starting with # are treated
 * like comments and ignored.
 *
 * @param context Kerberos 5 context.
 * @param file file with acl listed in the file.
 * @param format format to match.
 * @param ... parameter to format string.
 *
 * @return Return an error code or 0.
 *
 * @sa krb5_acl_match_string
 * @ingroup krb5_support
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_acl_match_file(krb5_context context,
                    const char *file,
                    const char *format,
                    ...)
{
    krb5_error_code ret;
    struct acl_field *acl = NULL;
    char buf[256];
    va_list ap;
    FILE *f;
    krb5_boolean found;

    f = fopen(file, "r");
    if(f == NULL) {
        int save_errno = errno;
        rk_strerror_r(save_errno, buf, sizeof(buf));
        krb5_set_error_message(context, save_errno,
                               N_("open(%s): %s", "file, errno"),
                               file, buf);
        return save_errno;
    }
    rk_cloexec_file(f);

    va_start(ap, format);
    ret = acl_parse_format(context, &acl, format, ap);
    va_end(ap);
    if(ret) {
        fclose(f);
        return ret;
    }

    found = FALSE;
    while(fgets(buf, sizeof(buf), f)) {
        if(buf[0] == '#')
            continue;
        if(acl_match_acl(context, acl, buf)) {
            found = TRUE;
            break;
        }
        free_retv(acl);
    }

    fclose(f);
    acl_free_list(acl, !found);
    if (found) {
        return 0;
    } else {
        krb5_set_error_message(context, EACCES, N_("ACL did not match", ""));
        return EACCES;
    }
}