/* 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
 * 
 * Adapted to Apache by rst.
 *
 * dirkx - Added Authoritative control to allow passing on to lower
 *         modules if and only if the user-id 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.
 */

#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"

typedef struct auth_config_struct {
    char *auth_pwfile;
    char *auth_grpfile;
    int auth_authoritative;
} auth_config_rec;

static void *create_auth_dir_config(pool *p, char *d)
{
    auth_config_rec *sec =
    (auth_config_rec *) ap_pcalloc(p, sizeof(auth_config_rec));
    sec->auth_pwfile = NULL;	/* just to illustrate the default really */
    sec->auth_grpfile = NULL;	/* unless you have a broken HP cc */
    sec->auth_authoritative = 1;	/* keep the fortress secure by default */
    return sec;
}

static const char *set_auth_slot(cmd_parms *cmd, void *offset, char *f, char *t)
{
    if (t && strcmp(t, "standard"))
	return ap_pstrcat(cmd->pool, "Invalid auth file type: ", t, NULL);

    return ap_set_file_slot(cmd, offset, f);
}

static const command_rec auth_cmds[] =
{
    {"AuthUserFile", set_auth_slot,
     (void *) XtOffsetOf(auth_config_rec, auth_pwfile), OR_AUTHCFG, TAKE12,
     "text file containing user IDs and passwords"},
    {"AuthGroupFile", set_auth_slot,
     (void *) XtOffsetOf(auth_config_rec, auth_grpfile), OR_AUTHCFG, TAKE12,
     "text file containing group names and member user IDs"},
    {"AuthAuthoritative", ap_set_flag_slot,
     (void *) XtOffsetOf(auth_config_rec, auth_authoritative),
     OR_AUTHCFG, FLAG,
     "Set to 'off' to allow access control to be passed along to "
     "lower modules if the UserID is not known to this module"},
    {NULL}
};

module MODULE_VAR_EXPORT auth_module;

static char *get_pw(request_rec *r, char *user, char *auth_pwfile)
{
    configfile_t *f;
    char l[MAX_STRING_LEN];
    const char *rpw, *w;

    if (!(f = ap_pcfg_openfile(r->pool, auth_pwfile))) {
	ap_log_rerror(APLOG_MARK, APLOG_ERR, r,
		    "Could not open password file: %s", auth_pwfile);
	return NULL;
    }
    while (!(ap_cfg_getline(l, MAX_STRING_LEN, f))) {
	if ((l[0] == '#') || (!l[0]))
	    continue;
	rpw = l;
	w = ap_getword(r->pool, &rpw, ':');

	if (!strcmp(user, w)) {
	    ap_cfg_closefile(f);
	    return ap_getword(r->pool, &rpw, ':');
	}
    }
    ap_cfg_closefile(f);
    return NULL;
}

static table *groups_for_user(pool *p, char *user, char *grpfile)
{
    configfile_t *f;
    table *grps = ap_make_table(p, 15);
    pool *sp;
    char l[MAX_STRING_LEN];
    const char *group_name, *ll, *w;

    if (!(f = ap_pcfg_openfile(p, grpfile))) {
/*add?	aplog_error(APLOG_MARK, APLOG_ERR, NULL,
		    "Could not open group file: %s", grpfile);*/
	return NULL;
    }

    sp = ap_make_sub_pool(p);

    while (!(ap_cfg_getline(l, MAX_STRING_LEN, f))) {
	if ((l[0] == '#') || (!l[0]))
	    continue;
	ll = l;
	ap_clear_pool(sp);

	group_name = ap_getword(sp, &ll, ':');

	while (ll[0]) {
	    w = ap_getword_conf(sp, &ll);
	    if (!strcmp(w, user)) {
		ap_table_setn(grps, ap_pstrdup(p, group_name), "in");
		break;
	    }
	}
    }
    ap_cfg_closefile(f);
    ap_destroy_pool(sp);
    return grps;
}

/* These functions return 0 if client is OK, and proper error status
 * if not... either AUTH_REQUIRED, if we made a check, and it failed, or
 * SERVER_ERROR, if things are so totally confused that we couldn't
 * figure out how to tell if the client is authorized or not.
 *
 * If they return DECLINED, and all other modules also decline, that's
 * treated by the server core as a configuration error, logged and
 * reported as such.
 */

/* Determine user ID, and check if it really is that user, for HTTP
 * basic authentication...
 */

static int authenticate_basic_user(request_rec *r)
{
    auth_config_rec *sec =
    (auth_config_rec *) ap_get_module_config(r->per_dir_config, &auth_module);
    conn_rec *c = r->connection;
    const char *sent_pw;
    char *real_pw;
    char *invalid_pw;
    int res;

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

    if (!sec->auth_pwfile)
	return DECLINED;

    if (!(real_pw = get_pw(r, c->user, sec->auth_pwfile))) {
	if (!(sec->auth_authoritative))
	    return DECLINED;
	ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
		    "user %s not found: %s", c->user, r->uri);
	ap_note_basic_auth_failure(r);
	return AUTH_REQUIRED;
    }
    invalid_pw = ap_validate_password(sent_pw, real_pw);
    if (invalid_pw != NULL) {
	ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
		      "user %s: authentication failure for \"%s\": %s",
		      c->user, r->uri, invalid_pw);
	ap_note_basic_auth_failure(r);
	return AUTH_REQUIRED;
    }
    return OK;
}

/* Checking ID */

static int check_user_access(request_rec *r)
{
    auth_config_rec *sec =
    (auth_config_rec *) ap_get_module_config(r->per_dir_config, &auth_module);
    char *user = r->connection->user;
    int m = r->method_number;
    int method_restricted = 0;
    register int x;
    const char *t, *w;
    table *grpstatus;
    const array_header *reqs_arr = ap_requires(r);
    require_line *reqs;

    /* BUG FIX: tadc, 11-Nov-1995.  If there is no "requires" directive, 
     * then any user will do.
     */
    if (reqs_arr == NULL) {
	return (OK);
    }
    reqs = (require_line *) reqs_arr->elts;

    if (sec->auth_grpfile) {
	grpstatus = groups_for_user(r->pool, user, sec->auth_grpfile);
    }
    else {
	grpstatus = NULL;
    }

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

        if (! (reqs[x].method_mask & (1 << m))) {
            continue;
        }

	method_restricted = 1;

	t = reqs[x].requirement;
	w = ap_getword_white(r->pool, &t);
	if (strcmp(w, "valid-user") == 0) {
	    return OK;
        }
        /*
         * If requested, allow access if the user is valid and the
         * owner of the document.
         */
	if (strcmp(w, "file-owner") == 0) {
#if defined(WIN32) || defined(NETWARE) || defined(OS2)
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_INFO, r,
                          "'Require file-owner' not supported "
                          "on this platform, ignored");
            continue;
#else
            struct passwd *pwent;
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                          "checking for 'owner' access for file '%s'",
                          r->filename);
            if (r->finfo.st_ino == 0) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                              "no stat info for '%s'", r->filename);
                continue;
            }
            pwent = getpwuid(r->finfo.st_uid);
            if (pwent == NULL) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                              "no username for UID %d (owner of '%s')",
                              r->finfo.st_uid, r->filename);
            }
            else {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                              "checking authenticated user '%s' "
                              "against owner '%s' of '%s'",
                              user, pwent->pw_name, r->filename);
                if (strcmp(user, pwent->pw_name) == 0) {
                    return OK;
                }
                else {
                    continue;
                }
            }
#endif
        }
	if (strcmp(w, "file-group") == 0) {
#if defined(WIN32) || defined(NETWARE) || defined(OS2)
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_INFO, r,
                          "'Require file-group' not supported "
                          "on this platform, ignored");
            continue;
#else
            struct group *grent;
            if (sec->auth_grpfile == NULL) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_INFO, r,
                              "no AuthGroupFile, so 'file-group' "
                              "requirement cannot succeed for file '%s'",
                              r->filename);
                continue;
            }
            if (grpstatus == NULL) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_WARNING, r,
                              "authenticated user '%s' not a member of "
                              "any groups, so 'file-group' requirement "
                              "cannot succeed for file '%s'",
                              user, r->filename);
                continue;
            }
            ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                          "checking for 'group' access for file '%s'",
                          r->filename);
            if (r->finfo.st_ino == 0) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                              "no stat info for '%s'", r->filename);
                continue;
            }
            grent = getgrgid(r->finfo.st_gid);
            if (grent == NULL) {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                              "no group name for GID %d (owner of '%s')",
                              r->finfo.st_gid, r->filename);
            }
            else {
                ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_DEBUG, r,
                              "checking groups of authenticated user '%s' "
                              "against owner group '%s' of '%s'",
                              user, grent->gr_name, r->filename);
                if (ap_table_get(grpstatus, grent->gr_name) != NULL) {
                    return OK;
                }
                else {
                    continue;
                }
            }
#endif
        }
	if (strcmp(w, "user") == 0) {
	    while (t[0] != '\0') {
		w = ap_getword_conf(r->pool, &t);
		if (strcmp(user, w) == 0) {
		    return OK;
                }
	    }
	}
	else if (strcmp(w, "group") == 0) {
	    if (grpstatus == NULL) {
		return DECLINED;	/* DBM group?  Something else? */
            }

	    while (t[0]) {
		w = ap_getword_conf(r->pool, &t);
		if (ap_table_get(grpstatus, w)) {
		    return OK;
                }
	    }
	}
        else if (sec->auth_authoritative) {
	    /* if we aren't authoritative, any require directive could be
	     * valid even if we don't grok it.  However, if we are 
	     * authoritative, we can warn the user they did something wrong.
	     * That something could be a missing "AuthAuthoritative off", but
	     * more likely is a typo in the require directive.
	     */
	    ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
                          "access to %s failed, "
                          "reason: unknown require directive:"
                          "\"%s\"", r->uri, reqs[x].requirement);
	}
    }

    if (! method_restricted) {
	return OK;
    }

    if (! sec->auth_authoritative) {
	return DECLINED;
    }

    ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, r,
                  "access to %s failed, reason: user %s not allowed access",
                  r->uri, user);
	
    ap_note_basic_auth_failure(r);
    return AUTH_REQUIRED;
}

module MODULE_VAR_EXPORT auth_module =
{
    STANDARD_MODULE_STUFF,
    NULL,			/* initializer */
    create_auth_dir_config,	/* dir config creater */
    NULL,			/* dir merger --- default is to override */
    NULL,			/* server config */
    NULL,			/* merge server config */
    auth_cmds,			/* command table */
    NULL,			/* handlers */
    NULL,			/* filename translation */
    authenticate_basic_user,	/* check_user_id */
    check_user_access,		/* check auth */
    NULL,			/* check access */
    NULL,			/* type_checker */
    NULL,			/* fixups */
    NULL,			/* logger */
    NULL,			/* header parser */
    NULL,			/* child_init */
    NULL,			/* child_exit */
    NULL			/* post read-request */
};
