/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * http_auth: authentication
 * 
 * Rob McCool & Brian Behlendorf.
 * 
 * Adapted to Apache by rst.
 *
 * dirkx - Added Authoritative control to allow passing on to lower  
 *         modules if and only if the userid is not known to this
 *         module. A known user with a faulty or absent password still
 *         causes an AuthRequired. The default is 'Authoritative', i.e.
 *         no control is passed along.
 */

#define APR_WANT_STRFUNC
#include "apr_want.h"
#include "apr_strings.h"
#include "apr_dbm.h"
#include "apr_md5.h"            /* for apr_password_validate */

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
#include "http_request.h"   /* for ap_hook_(check_user_id | auth_checker)*/


typedef struct {
    char *auth_dbmpwfile;
    char *auth_dbmgrpfile;
    char *auth_dbmtype;
    int auth_dbmauthoritative;
} dbm_auth_config_rec;

static void *create_dbm_auth_dir_config(apr_pool_t *p, char *d)
{
    dbm_auth_config_rec *conf = apr_palloc(p, sizeof(*conf));

    conf->auth_dbmpwfile = NULL;
    conf->auth_dbmgrpfile = NULL;
    conf->auth_dbmtype = "default";
    conf->auth_dbmauthoritative = 1;  /* fortress is secure by default */

    return conf;
}

static const char *set_dbm_slot(cmd_parms *cmd, void *offset,
                                const char *f, const char *t)
{
    if (!t || strcmp(t, "dbm"))
        return DECLINE_CMD;

    return ap_set_file_slot(cmd, offset, f);
}

static const char *set_dbm_type(cmd_parms *cmd, 
                                void *dir_config, 
                                const char *arg)
{
    dbm_auth_config_rec *conf = dir_config;
   
    conf->auth_dbmtype = apr_pstrdup(cmd->pool, arg);
    return NULL;
}

static const command_rec dbm_auth_cmds[] =
{
    AP_INIT_TAKE1("AuthDBMUserFile", ap_set_file_slot,
     (void *)APR_OFFSETOF(dbm_auth_config_rec, auth_dbmpwfile),
     OR_AUTHCFG, "dbm database file containing user IDs and passwords"),
    AP_INIT_TAKE1("AuthDBMGroupFile", ap_set_file_slot,
     (void *)APR_OFFSETOF(dbm_auth_config_rec, auth_dbmgrpfile),
     OR_AUTHCFG, "dbm database file containing group names and member user IDs"),
    AP_INIT_TAKE12("AuthUserFile", set_dbm_slot,
     (void *)APR_OFFSETOF(dbm_auth_config_rec, auth_dbmpwfile),
     OR_AUTHCFG, NULL),
    AP_INIT_TAKE12("AuthGroupFile", set_dbm_slot,
     (void *)APR_OFFSETOF(dbm_auth_config_rec, auth_dbmgrpfile),
     OR_AUTHCFG, NULL),
    AP_INIT_TAKE1("AuthDBMType", set_dbm_type,
     NULL,
     OR_AUTHCFG, "what type of DBM file the user file is"),
    AP_INIT_FLAG("AuthDBMAuthoritative", ap_set_flag_slot,
     (void *)APR_OFFSETOF(dbm_auth_config_rec, auth_dbmauthoritative),
     OR_AUTHCFG, "Set to 'no' to allow access control to be passed along to lower modules, if the UserID is not known in this module"),
    {NULL}
};

module AP_MODULE_DECLARE_DATA auth_dbm_module;

static char *get_dbm_pw(request_rec *r, 
                        char *user, 
                        char *auth_dbmpwfile, 
                        char *dbtype)
{
    apr_dbm_t *f;
    apr_datum_t d, q;
    char *pw = NULL;
    apr_status_t retval;
    q.dptr = user;
#ifndef NETSCAPE_DBM_COMPAT
    q.dsize = strlen(q.dptr);
#else
    q.dsize = strlen(q.dptr) + 1;
#endif

    retval = apr_dbm_open_ex(&f, dbtype, auth_dbmpwfile, APR_DBM_READONLY, 
                             APR_OS_DEFAULT, r->pool);
    if (retval != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, retval, r,
                      "could not open dbm (type %s) auth file: %s", dbtype, 
                      auth_dbmpwfile);
        return NULL;
    }
    if (apr_dbm_fetch(f, q, &d) == APR_SUCCESS && d.dptr) {
        pw = apr_palloc(r->pool, d.dsize + 1);
        strncpy(pw, d.dptr, d.dsize);
        pw[d.dsize] = '\0'; /* Terminate the string */
    }

    apr_dbm_close(f);
    return pw;
}

/* We do something strange with the group file.  If the group file
 * contains any : we assume the format is
 *      key=username value=":"groupname [":"anything here is ignored]
 * otherwise we now (0.8.14+) assume that the format is
 *      key=username value=groupname
 * The first allows the password and group files to be the same 
 * physical DBM file;   key=username value=password":"groupname[":"anything]
 *
 * mark@telescope.org, 22Sep95
 */

static char *get_dbm_grp(request_rec *r, char *user, char *auth_dbmgrpfile, 
                         char *dbtype)
{
    char *grp_data = get_dbm_pw(r, user, auth_dbmgrpfile,dbtype);
    char *grp_colon;
    char *grp_colon2;

    if (grp_data == NULL)
        return NULL;

    if ((grp_colon = strchr(grp_data, ':')) != NULL) {
        grp_colon2 = strchr(++grp_colon, ':');
        if (grp_colon2)
            *grp_colon2 = '\0';
        return grp_colon;
    }
    return grp_data;
}

static int dbm_authenticate_basic_user(request_rec *r)
{
    dbm_auth_config_rec *conf = ap_get_module_config(r->per_dir_config,
                                                     &auth_dbm_module);
    const char *sent_pw;
    char *real_pw, *colon_pw;
    apr_status_t invalid_pw;
    int res;

    if ((res = ap_get_basic_auth_pw(r, &sent_pw)))
        return res;

    if (!conf->auth_dbmpwfile)
        return DECLINED;

    if (!(real_pw = get_dbm_pw(r, r->user, conf->auth_dbmpwfile,
                               conf->auth_dbmtype))) {
        if (!(conf->auth_dbmauthoritative))
            return DECLINED;
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "DBM user %s not found: %s", r->user, r->filename);
        ap_note_basic_auth_failure(r);
        return HTTP_UNAUTHORIZED;
    }
    /* Password is up to first : if exists */
    colon_pw = strchr(real_pw, ':');
    if (colon_pw) {
        *colon_pw = '\0';
    }
    invalid_pw = apr_password_validate(sent_pw, real_pw);
    if (invalid_pw != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                      "DBM user %s: authentication failure for \"%s\": "
                      "Password Mismatch",
                      r->user, r->uri);
        ap_note_basic_auth_failure(r);
        return HTTP_UNAUTHORIZED;
    }
    return OK;
}

/* Checking ID */

static int dbm_check_auth(request_rec *r)
{
    dbm_auth_config_rec *conf = ap_get_module_config(r->per_dir_config,
                                                     &auth_dbm_module);
    char *user = r->user;
    int m = r->method_number;

    const apr_array_header_t *reqs_arr = ap_requires(r);
    require_line *reqs = reqs_arr ? (require_line *) reqs_arr->elts : NULL;

    register int x;
    const char *t;
    char *w;

    if (!conf->auth_dbmgrpfile)
        return DECLINED;
    if (!reqs_arr)
        return DECLINED;

    for (x = 0; x < reqs_arr->nelts; x++) {

        if (!(reqs[x].method_mask & (AP_METHOD_BIT << m)))
            continue;

        t = reqs[x].requirement;
        w = ap_getword_white(r->pool, &t);

        if (!strcmp(w, "group") && conf->auth_dbmgrpfile) {
            const char *orig_groups, *groups;
            char *v;

            if (!(groups = get_dbm_grp(r, user, conf->auth_dbmgrpfile,
                                       conf->auth_dbmtype))) {
                if (!(conf->auth_dbmauthoritative))
                    return DECLINED;
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                            "user %s not in DBM group file %s: %s",
                            user, conf->auth_dbmgrpfile, r->filename);
                ap_note_basic_auth_failure(r);
                return HTTP_UNAUTHORIZED;
            }
            orig_groups = groups;
            while (t[0]) {
                w = ap_getword_white(r->pool, &t);
                groups = orig_groups;
                while (groups[0]) {
                    v = ap_getword(r->pool, &groups, ',');
                    if (!strcmp(v, w))
                        return OK;
                }
            }
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
                          "user %s not in right group: %s",
                          user, r->filename);
            ap_note_basic_auth_failure(r);
            return HTTP_UNAUTHORIZED;
        }
    }

    return DECLINED;
}

static void register_hooks(apr_pool_t *p)
{
    ap_hook_check_user_id(dbm_authenticate_basic_user, NULL, NULL,
                          APR_HOOK_MIDDLE);
    ap_hook_auth_checker(dbm_check_auth, NULL, NULL, APR_HOOK_MIDDLE);
}

module AP_MODULE_DECLARE_DATA auth_dbm_module =
{
    STANDARD20_MODULE_STUFF,
    create_dbm_auth_dir_config, /* dir config creater */
    NULL,                       /* dir merger --- default is to override */
    NULL,                       /* server config */
    NULL,                       /* merge server config */
    dbm_auth_cmds,              /* command apr_table_t */
    register_hooks              /* register hooks */
};