2 * This file is part of DisOrder
3 * Copyright (C) 2007, 2008 Richard Kettlewell
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
20 /** @file lib/cookies.c
21 * @brief Cookie support
37 #include "configuration.h"
41 /** @brief Hash function used in signing HMAC */
42 #define ALGO GCRY_MD_SHA1
44 /** @brief Size of key to use */
47 /** @brief Signing key */
48 static uint8_t signing_key
[HASHSIZE
];
50 /** @brief Previous signing key */
51 static uint8_t old_signing_key
[HASHSIZE
];
53 /** @brief Signing key validity limit or 0 if none */
54 static time_t signing_key_validity_limit
;
56 /** @brief Hash of revoked cookies */
59 /** @brief Callback to expire revocation list */
60 static int revoked_cleanup_callback(const char *key
, void *value
,
62 if(*(time_t *)value
< *(time_t *)u
)
63 hash_remove(revoked
, key
);
67 /** @brief Generate a new key */
68 static void newkey(void) {
72 memcpy(old_signing_key
, signing_key
, HASHSIZE
);
73 gcry_randomize(signing_key
, HASHSIZE
, GCRY_STRONG_RANDOM
);
74 signing_key_validity_limit
= now
+ config
->cookie_key_lifetime
;
75 /* Now is a good time to clean up the revocation list... */
77 hash_foreach(revoked
, revoked_cleanup_callback
, &now
);
80 /** @brief Base64 mapping table for cookies
82 * Stupid Safari cannot cope with quoted cookies, so cookies had better not
83 * need quoting. We use $ to separate the parts of the cookie and +%# to where
84 * MIME uses +/=; see @ref base64.c. See http_separator() for the characters
87 static const char cookie_base64_table
[] =
88 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+%#";
90 /** @brief Sign @p subject with @p key and return the base64 of the result
91 * @param key Key to sign with (@ref HASHSIZE bytes)
92 * @param subject Subject string
93 * @return Base64-encoded signature or NULL
95 static char *sign(const uint8_t *key
,
96 const char *subject
) {
102 if((e
= gcry_md_open(&h
, ALGO
, GCRY_MD_FLAG_HMAC
))) {
103 error(0, "gcry_md_open: %s", gcry_strerror(e
));
106 if((e
= gcry_md_setkey(h
, key
, HASHSIZE
))) {
107 error(0, "gcry_md_setkey: %s", gcry_strerror(e
));
111 gcry_md_write(h
, subject
, strlen(subject
));
112 sig
= gcry_md_read(h
, ALGO
);
113 sig64
= generic_to_base64(sig
, HASHSIZE
, cookie_base64_table
);
118 /** @brief Create a login cookie
119 * @param user Username
120 * @return Cookie or NULL
122 char *make_cookie(const char *user
) {
123 const char *password
;
125 char *b
, *bp
, *c
, *g
;
127 /* dollar signs aren't allowed in usernames */
128 if(strchr(user
, '$')) {
129 error(0, "make_cookie for username with dollar sign");
132 /* look up the password */
133 password
= trackdb_get_password(user
);
135 error(0, "make_cookie for nonexistent user");
138 /* make sure we have a valid signing key */
140 if(now
>= signing_key_validity_limit
)
142 /* construct the subject */
143 byte_xasprintf(&b
, "%jx$%s$", (intmax_t)now
+ config
->cookie_login_lifetime
,
144 urlencodestring(user
));
145 byte_xasprintf(&bp
, "%s%s", b
, password
);
147 if(!(g
= sign(signing_key
, bp
)))
149 /* put together the final cookie */
150 byte_xasprintf(&c
, "%s%s", b
, g
);
154 /** @brief Verify a cookie
155 * @param cookie Cookie to verify
156 * @param rights Where to store rights value
157 * @return Verified user or NULL
159 char *verify_cookie(const char *cookie
, rights_type
*rights
) {
163 char *user
, *bp
, *sig
;
164 const char *password
;
167 /* check the revocation list */
168 if(revoked
&& hash_find(revoked
, cookie
)) {
169 error(0, "attempt to log in with revoked cookie");
172 /* parse the cookie */
174 t
= strtoimax(cookie
, &c1
, 16);
176 error(errno
, "error parsing cookie timestamp");
180 error(0, "invalid cookie timestamp");
183 /* There'd better be two dollar signs */
184 c2
= strchr(c1
+ 1, '$');
186 error(0, "invalid cookie syntax");
189 /* Extract the username */
190 user
= xstrndup(c1
+ 1, c2
- (c1
+ 1));
194 error(0, "cookie has expired");
197 /* look up the password */
198 k
= trackdb_getuserinfo(user
);
200 error(0, "verify_cookie for nonexistent user");
203 password
= kvp_get(k
, "password");
204 if(!password
) password
= "";
205 if(parse_rights(kvp_get(k
, "rights"), rights
, 1))
207 /* construct the expected subject. We re-encode the timestamp and the
209 byte_xasprintf(&bp
, "%jx$%s$%s", t
, urlencodestring(user
), password
);
210 /* Compute the expected signature. NB we base64 the expected signature and
211 * compare that rather than exposing our base64 parser to the cookie. */
212 if(!(sig
= sign(signing_key
, bp
)))
214 if(!strcmp(sig
, c2
+ 1))
216 /* that didn't match, try the old key */
217 if(!(sig
= sign(old_signing_key
, bp
)))
219 if(!strcmp(sig
, c2
+ 1))
221 /* that didn't match either */
222 error(0, "cookie signature does not match");
226 /** @brief Revoke a cookie
227 * @param cookie Cookie to revoke
229 * Further attempts to log in with @p cookie will fail.
231 void revoke_cookie(const char *cookie
) {
235 /* find the cookie's expiry time */
237 when
= (time_t)strtoimax(cookie
, &ptr
, 16);
238 /* reject bogus cookies */
243 /* make sure the revocation list exists */
245 revoked
= hash_new(sizeof(time_t));
246 /* add the cookie to it; its value is the expiry time */
247 hash_add(revoked
, cookie
, &when
, HASH_INSERT
);