modules/aaa/mod_authn_dbm.c

/* ====================================================================
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 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

/*
 * 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)*/

#include "mod_auth.h"

typedef struct {
    char *pwfile;
    char *dbmtype;
    int authoritative;
} authn_dbm_config_rec;

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

    conf->pwfile = NULL;
    conf->dbmtype = "default";
    conf->authoritative = 1;  /* fortress is secure by default */

    return conf;
}

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

static const command_rec authn_dbm_cmds[] =
{
    AP_INIT_TAKE1("AuthDBMUserFile", ap_set_file_slot,
     (void *)APR_OFFSETOF(authn_dbm_config_rec, pwfile),
     OR_AUTHCFG, "dbm database file containing user IDs and passwords"),
    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(authn_dbm_config_rec, authoritative),
     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 authn_dbm_module;

static apr_status_t fetch_dbm(const char *dbmtype, const char *dbmfile,
                              const char *user, apr_datum_t *val,
                              apr_pool_t *pool)
{
    apr_dbm_t *f;
    apr_datum_t key;
    apr_status_t rv;

    rv = apr_dbm_open_ex(&f, dbmtype, dbmfile, APR_DBM_READONLY, 
                         APR_OS_DEFAULT, pool);

    if (rv != APR_SUCCESS) {
        return rv;
    }

    key.dptr = (char*)user;
#ifndef NETSCAPE_DBM_COMPAT
    key.dsize = strlen(key.dptr);
#else
    key.dsize = strlen(key.dptr) + 1;
#endif

    rv = apr_dbm_fetch(f, key, val);

    apr_dbm_close(f);
    
    return rv;
}

static authn_status check_dbm_pw(request_rec *r, const char *user,
                                 const char *password)
{
    authn_dbm_config_rec *conf = ap_get_module_config(r->per_dir_config,
                                                      &authn_dbm_module);
    apr_datum_t dbm_pw;
    apr_status_t rv;
    char *dbm_password;

    rv = fetch_dbm(conf->dbmtype, conf->pwfile, user, &dbm_pw, r->pool);

    if (rv != APR_SUCCESS) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                      "could not open dbm (type %s) auth file: %s",
                      conf->dbmtype, conf->pwfile);
        return AUTH_GENERAL_ERROR;
    }

    if (dbm_pw.dptr) {
        dbm_password = apr_pstrmemdup(r->pool, dbm_pw.dptr, dbm_pw.dsize);
    }

    if (!dbm_password) {
        return AUTH_USER_NOT_FOUND;
    }

    rv = apr_password_validate(password, dbm_password);

    if (rv != APR_SUCCESS) {
        return AUTH_DENIED;
    }

    return AUTH_GRANTED;
}

static const authn_provider authn_dbm_provider =
{
    &check_dbm_pw,
    NULL,               /* No realm support yet. */
};

static void register_hooks(apr_pool_t *p)
{
    authn_register_provider(p, "dbm", &authn_dbm_provider);
}

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