cryb-to/lib/oath/cryb_oath_key_from_uri.c

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/*-
* Copyright (c) 2013-2016 The University of Oslo
* Copyright (c) 2016-2017 Dag-Erling Smørgrav
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* 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.
*/
#include "cryb/impl.h"
#include <inttypes.h>
#include <string.h>
#include <cryb/rfc3986.h>
#include <cryb/rfc4648.h>
#include <cryb/strlcmp.h>
#include <cryb/oath.h>
/*
* OATH
*
* Creates an OATH key from a Google otpauth URI
*/
struct oath_key *
oath_key_from_uri(const char *uri)
{
char name[64], value[256];
size_t namelen, valuelen;
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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 = sizeof key->label;
if (percent_decode(p, q - p, key->label, &key->labellen) != 0)
goto invalid;
p = q + 1;
/* extract parameters */
key->counter = UINT64_MAX;
key->lastused = UINT64_MAX;
while (*p != '\0') {
/* locate name-value separator */
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if ((q = strchr(p, '=')) == NULL)
goto invalid;
q = q + 1;
/* locate end of value */
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if ((r = strchr(p, '&')) == NULL)
r = strchr(p, '\0');
if (r < q)
/* & before = */
goto invalid;
/* decode name and value*/
namelen = sizeof name;
valuelen = sizeof value;
if (percent_decode(p, q - p - 1, name, &namelen) != 0 ||
percent_decode(q, r - q, value, &valuelen) != 0)
goto invalid;
if (strcmp("secret", name) == 0) {
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if (key->keylen != 0)
/* dupe */
goto invalid;
key->keylen = sizeof key->key;
if (base32_decode(value, valuelen, key->key, &key->keylen) != 0)
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goto invalid;
} else if (strcmp("algorithm", name) == 0) {
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if (key->hash != oh_undef)
/* dupe */
goto invalid;
if (strcmp("SHA1", value) == 0)
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key->hash = oh_sha1;
else if (strcmp("SHA256", value) == 0)
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key->hash = oh_sha256;
else if (strcmp("SHA512", value) == 0)
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key->hash = oh_sha512;
else if (strcmp("MD5", value) == 0)
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key->hash = oh_md5;
else
goto invalid;
} else if (strcmp("digits", name) == 0) {
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if (key->digits != 0)
/* dupe */
goto invalid;
/* only 6 or 8 */
if (valuelen != 1 || (*value != '6' && *value != '8'))
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goto invalid;
key->digits = *q - '0';
} else if (strcmp("counter", name) == 0) {
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if (key->counter != UINT64_MAX)
/* dupe */
goto invalid;
n = strtoumax(value, &e, 10);
if (e == value || *e != '\0' || n >= UINT64_MAX)
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goto invalid;
key->counter = (uint64_t)n;
} else if (strcmp("lastused", name) == 0) {
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if (key->lastused != UINT64_MAX)
/* dupe */
goto invalid;
n = strtoumax(value, &e, 10);
if (e == value || *e != '\0' || n >= UINT64_MAX)
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goto invalid;
key->lastused = (uint64_t)n;
} else if (strcmp("period", name) == 0) {
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if (key->timestep != 0)
/* dupe */
goto invalid;
n = strtoumax(value, &e, 10);
if (e == value || *e != '\0' || n > OATH_MAX_TIMESTEP)
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goto invalid;
key->timestep = n;
} else if (strcmp("issuer", name) == 0) {
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// noop for now
} 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 function 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
*/