source: openpam/trunk/lib/liboath/oath_key_from_uri.c @ 772

/*-
 * Copyright (c) 2013-2014 Universitetet i Oslo
 * 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. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * 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.
 *
 * $Id: oath_key_from_uri.c 772 2014-03-09 11:45:05Z des $
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <sys/types.h>

#include <inttypes.h>
#include <string.h>

#include <security/pam_appl.h>
#include <security/openpam.h>

#include "openpam_strlcmp.h"

#include <security/oath.h>

/*
 * OATH
 *
 * Creates an OATH key from a Google otpauth URI
 */

struct oath_key *
oath_key_from_uri(const char *uri)
{
        struct oath_key *key;
        const char *p, *q, *r;
        uintmax_t n;
        char *e;

        if ((key = oath_key_alloc()) == NULL)
                return (NULL);

        /* check method */
        p = uri;
        if (strlcmp("otpauth://", p, 10) != 0)
                goto invalid;
        p += 10;

        /* check mode (hotp = event, totp = time-sync) */
        if ((q = strchr(p, '/')) == NULL)
                goto invalid;
        if (strlcmp("hotp", p, q - p) == 0) {
                key->mode = om_hotp;
        } else if (strlcmp("totp", p, q - p) == 0) {
                key->mode = om_totp;
        } else {
                goto invalid;
        }
        p = q + 1;

        /* extract label */
        if ((q = strchr(p, '?')) == NULL)
                goto invalid;
        key->labellen = oath_uri_decode(p, q - p, key->label,
            sizeof key->label);
        if (key->labellen > sizeof key->label)
                goto invalid;
        p = q + 1;

        /* extract parameters */
        key->counter = UINT64_MAX;
        key->lastused = UINT64_MAX;
        while (*p != '\0') {
                if ((q = strchr(p, '=')) == NULL)
                        goto invalid;
                q = q + 1;
                if ((r = strchr(p, '&')) == NULL)
                        r = strchr(p, '\0');
                if (r < q)
                        /* & before = */
                        goto invalid;
                /* p points to key, q points to value, r points to & or NUL */
                if (strlcmp("secret=", p, q - p) == 0) {
                        if (key->keylen != 0)
                                /* dupe */
                                goto invalid;
                        key->keylen = sizeof key->key;
                        if (base32_dec(q, r - q, (char *)key->key, &key->keylen) != 0)
                                goto invalid;
                        if (base32_enclen(key->keylen) != (size_t)(r - q))
                                goto invalid;
                } else if (strlcmp("algorithm=", p, q - p) == 0) {
                        if (key->hash != oh_undef)
                                /* dupe */
                                goto invalid;
                        if (strlcmp("SHA1", q, r - q) == 0)
                                key->hash = oh_sha1;
                        else if (strlcmp("SHA256", q, r - q) == 0)
                                key->hash = oh_sha256;
                        else if (strlcmp("SHA512", q, r - q) == 0)
                                key->hash = oh_sha512;
                        else if (strlcmp("MD5", q, r - q) == 0)
                                key->hash = oh_md5;
                        else
                                goto invalid;
                } else if (strlcmp("digits=", p, q - p) == 0) {
                        if (key->digits != 0)
                                /* dupe */
                                goto invalid;
                        /* only 6 or 8 */
                        if (r - q != 1 || (*q != '6' && *q != '8'))
                                goto invalid;
                        key->digits = *q - '0';
                } else if (strlcmp("counter=", p, q - p) == 0) {
                        if (key->counter != UINT64_MAX)
                                /* dupe */
                                goto invalid;
                        n = strtoumax(q, &e, 10);
                        if (e != r || n >= UINT64_MAX)
                                goto invalid;
                        key->counter = (uint64_t)n;
                } else if (strlcmp("lastused=", p, q - p) == 0) {
                        if (key->lastused != UINT64_MAX)
                                /* dupe */
                                goto invalid;
                        n = strtoumax(q, &e, 10);
                        if (e != r || n >= UINT64_MAX)
                                goto invalid;
                        key->lastused = (uint64_t)n;
                } else if (strlcmp("period=", p, q - p) == 0) {
                        if (key->timestep != 0)
                                /* dupe */
                                goto invalid;
                        n = strtoumax(q, &e, 10);
                        if (e != r || n > OATH_MAX_TIMESTEP)
                                goto invalid;
                        key->timestep = n;
                } else {
                        goto invalid;
                }
                /* final parameter? */
                if (*r == '\0')
                        break;
                /* skip & and continue */
                p = r + 1;
        }

        /* sanity checks and default values */
        if (key->mode == om_hotp) {
                if (key->counter == UINT64_MAX)
                        key->counter = 0;
                if (key->timestep != 0)
                        goto invalid;
                if (key->lastused != UINT64_MAX)
                        goto invalid;
        } else if (key->mode == om_totp) {
                if (key->counter != UINT64_MAX)
                        goto invalid;
                if (key->timestep == 0)
                        key->timestep = OATH_DEF_TIMESTEP;
                if (key->lastused == UINT64_MAX)
                        key->lastused = 0;
        } else {
                /* unreachable */
                oath_key_free(key);
                return (NULL);
        }
        if (key->hash == oh_undef)
                key->hash = oh_sha1;
        if (key->digits == 0)
                key->digits = 6;
        if (key->keylen == 0)
                goto invalid;
        return (key);

invalid:
        openpam_log(PAM_LOG_NOTICE, "invalid OATH URI: %s", uri);
        oath_key_free(key);
        return (NULL);
}

/**
 * The =oath_key_from_uri parses a Google otpauth URI into a key
 * structure.
 *
 * The =uri parameter points to a NUL-terminated string containing the
 * URI.
 *
 * Keys created with =oath_key_from_uri must be freed using
 * =oath_key_free.
 *
 * >oath_key_alloc
 * >oath_key_free
 * >oath_key_to_uri
 *
 * REFERENCES
 *
 * https://code.google.com/p/google-authenticator/wiki/KeyUriFormat
 *
 * AUTHOR UIO
 */