2 * This file is part of DisOrder
3 * Copyright (C) 2007 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
42 #include "configuration.h"
47 /** @brief Hash function used in signing HMAC */
48 #define ALGO GCRY_MD_SHA1
50 /** @brief Size of key to use */
53 /** @brief Signing key */
54 static uint8_t signing_key[HASHSIZE];
56 /** @brief Previous signing key */
57 static uint8_t old_signing_key[HASHSIZE];
59 /** @brief Signing key validity limit or 0 if none */
60 static time_t signing_key_validity_limit;
62 /** @brief Hash of revoked cookies */
65 /** @brief Callback to expire revocation list */
66 static int revoked_cleanup_callback(const char *key, void *value,
68 if(*(time_t *)value < *(time_t *)u)
69 hash_remove(revoked, key);
73 /** @brief Generate a new key */
74 static void newkey(void) {
78 memcpy(old_signing_key, signing_key, HASHSIZE);
79 gcry_randomize(signing_key, HASHSIZE, GCRY_STRONG_RANDOM);
80 signing_key_validity_limit = now + config->cookie_key_lifetime;
81 /* Now is a good time to clean up the revocation list... */
83 hash_foreach(revoked, revoked_cleanup_callback, &now);
86 /** @brief Base64 mapping table for cookies
88 * Stupid Safari cannot cope with quoted cookies, so cookies had better not
89 * need quoting. We use $ to separate the parts of the cookie and +%# to where
90 * MIME uses +/=; see @ref base64.c. See http_separator() for the characters
93 static const char cookie_base64_table[] =
94 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+%#";
96 /** @brief Sign @p subject with @p key and return the base64 of the result
97 * @param key Key to sign with (@ref HASHSIZE bytes)
98 * @param subject Subject string
99 * @return Base64-encoded signature or NULL
101 static char *sign(const uint8_t *key,
102 const char *subject) {
108 if((e = gcry_md_open(&h, ALGO, GCRY_MD_FLAG_HMAC))) {
109 error(0, "gcry_md_open: %s", gcry_strerror(e));
112 if((e = gcry_md_setkey(h, key, HASHSIZE))) {
113 error(0, "gcry_md_setkey: %s", gcry_strerror(e));
117 gcry_md_write(h, subject, strlen(subject));
118 sig = gcry_md_read(h, ALGO);
119 sig64 = generic_to_base64(sig, HASHSIZE, cookie_base64_table);
124 /** @brief Create a login cookie
125 * @param user Username
126 * @return Cookie or NULL
128 char *make_cookie(const char *user) {
129 const char *password;
131 char *b, *bp, *c, *g;
133 /* dollar signs aren't allowed in usernames */
134 if(strchr(user, '$')) {
135 error(0, "make_cookie for username with dollar sign");
138 /* look up the password */
139 password = trackdb_get_password(user);
141 error(0, "make_cookie for nonexistent user");
144 /* make sure we have a valid signing key */
146 if(now >= signing_key_validity_limit)
148 /* construct the subject */
149 byte_xasprintf(&b, "%jx$%s$", (intmax_t)now + config->cookie_login_lifetime,
150 urlencodestring(user));
151 byte_xasprintf(&bp, "%s%s", b, password);
153 if(!(g = sign(signing_key, bp)))
155 /* put together the final cookie */
156 byte_xasprintf(&c, "%s%s", b, g);
160 /** @brief Verify a cookie
161 * @param cookie Cookie to verify
162 * @param rights Where to store rights value
163 * @return Verified user or NULL
165 char *verify_cookie(const char *cookie, rights_type *rights) {
169 char *user, *bp, *sig;
170 const char *password;
173 /* check the revocation list */
174 if(revoked && hash_find(revoked, cookie)) {
175 error(0, "attempt to log in with revoked cookie");
178 /* parse the cookie */
180 t = strtoimax(cookie, &c1, 16);
182 error(errno, "error parsing cookie timestamp");
186 error(0, "invalid cookie timestamp");
189 /* There'd better be two dollar signs */
190 c2 = strchr(c1 + 1, '$');
192 error(0, "invalid cookie syntax");
195 /* Extract the username */
196 user = xstrndup(c1 + 1, c2 - (c1 + 1));
200 error(0, "cookie has expired");
203 /* look up the password */
204 k = trackdb_getuserinfo(user);
206 error(0, "verify_cookie for nonexistent user");
209 password = kvp_get(k, "password");
210 if(!password) password = "";
211 if(parse_rights(kvp_get(k, "rights"), rights, 1))
213 /* construct the expected subject. We re-encode the timestamp and the
215 byte_xasprintf(&bp, "%jx$%s$%s", t, urlencodestring(user), password);
216 /* Compute the expected signature. NB we base64 the expected signature and
217 * compare that rather than exposing our base64 parser to the cookie. */
218 if(!(sig = sign(signing_key, bp)))
220 if(!strcmp(sig, c2 + 1))
222 /* that didn't match, try the old key */
223 if(!(sig = sign(old_signing_key, bp)))
225 if(!strcmp(sig, c2 + 1))
227 /* that didn't match either */
228 error(0, "cookie signature does not match");
232 /** @brief Revoke a cookie
233 * @param cookie Cookie to revoke
235 * Further attempts to log in with @p cookie will fail.
237 void revoke_cookie(const char *cookie) {
241 /* find the cookie's expiry time */
243 when = (time_t)strtoimax(cookie, &ptr, 16);
244 /* reject bogus cookies */
249 /* make sure the revocation list exists */
251 revoked = hash_new(sizeof(time_t));
252 /* add the cookie to it; its value is the expiry time */
253 hash_add(revoked, cookie, &when, HASH_INSERT);