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 3 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU 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, see <http://www.gnu.org/licenses/>.
18 /** @file lib/cookies.c
19 * @brief Cookie support
35 #include "configuration.h"
40 /** @brief Hash function used in signing HMAC */
41 #define ALGO GCRY_MD_SHA1
43 /** @brief Size of key to use */
46 /** @brief Signing key */
47 static uint8_t signing_key[HASHSIZE];
49 /** @brief Previous signing key */
50 static uint8_t old_signing_key[HASHSIZE];
52 /** @brief Signing key validity limit or 0 if none */
53 static time_t signing_key_validity_limit;
55 /** @brief Hash of revoked cookies */
58 /** @brief Callback to expire revocation list */
59 static int revoked_cleanup_callback(const char *key, void *value,
61 if(*(time_t *)value < *(time_t *)u)
62 hash_remove(revoked, key);
66 /** @brief Generate a new key */
67 static void newkey(void) {
71 memcpy(old_signing_key, signing_key, HASHSIZE);
72 gcry_randomize(signing_key, HASHSIZE, GCRY_STRONG_RANDOM);
73 signing_key_validity_limit = now + config->cookie_key_lifetime;
74 /* Now is a good time to clean up the revocation list... */
76 hash_foreach(revoked, revoked_cleanup_callback, &now);
79 /** @brief Base64 mapping table for cookies
81 * Stupid Safari cannot cope with quoted cookies, so cookies had better not
82 * need quoting. We use $ to separate the parts of the cookie and +%# to where
83 * MIME uses +/=; see @ref base64.c. See http_separator() for the characters
86 static const char cookie_base64_table[] =
87 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+%#";
89 /** @brief Sign @p subject with @p key and return the base64 of the result
90 * @param key Key to sign with (@ref HASHSIZE bytes)
91 * @param subject Subject string
92 * @return Base64-encoded signature or NULL
94 static char *sign(const uint8_t *key,
95 const char *subject) {
101 if((e = gcry_md_open(&h, ALGO, GCRY_MD_FLAG_HMAC))) {
102 disorder_error(0, "gcry_md_open: %s", gcry_strerror(e));
105 if((e = gcry_md_setkey(h, key, HASHSIZE))) {
106 disorder_error(0, "gcry_md_setkey: %s", gcry_strerror(e));
110 gcry_md_write(h, subject, strlen(subject));
111 sig = gcry_md_read(h, ALGO);
112 sig64 = generic_to_base64(sig, HASHSIZE, cookie_base64_table);
117 /** @brief Create a login cookie
118 * @param user Username
119 * @return Cookie or NULL
121 char *make_cookie(const char *user) {
122 const char *password;
124 char *b, *bp, *c, *g;
126 /* dollar signs aren't allowed in usernames */
127 if(strchr(user, '$')) {
128 disorder_error(0, "make_cookie for username with dollar sign");
131 /* look up the password */
132 password = trackdb_get_password(user);
134 disorder_error(0, "make_cookie for nonexistent user");
137 /* make sure we have a valid signing key */
139 if(now >= signing_key_validity_limit)
141 /* construct the subject */
142 byte_xasprintf(&b, "%jx$%s$", (intmax_t)now + config->cookie_login_lifetime,
143 urlencodestring(user));
144 byte_xasprintf(&bp, "%s%s", b, password);
146 if(!(g = sign(signing_key, bp)))
148 /* put together the final cookie */
149 byte_xasprintf(&c, "%s%s", b, g);
153 /** @brief Verify a cookie
154 * @param cookie Cookie to verify
155 * @param rights Where to store rights value
156 * @return Verified user or NULL
158 char *verify_cookie(const char *cookie, rights_type *rights) {
162 char *user, *bp, *sig;
163 const char *password;
166 /* check the revocation list */
167 if(revoked && hash_find(revoked, cookie)) {
168 disorder_error(0, "attempt to log in with revoked cookie");
171 /* parse the cookie */
173 t = strtoimax(cookie, &c1, 16);
175 disorder_error(errno, "error parsing cookie timestamp");
179 disorder_error(0, "invalid cookie timestamp");
182 /* There'd better be two dollar signs */
183 c2 = strchr(c1 + 1, '$');
185 disorder_error(0, "invalid cookie syntax");
188 /* Extract the username */
189 user = xstrndup(c1 + 1, c2 - (c1 + 1));
193 disorder_error(0, "cookie has expired");
196 /* look up the password */
197 k = trackdb_getuserinfo(user);
199 disorder_error(0, "verify_cookie for nonexistent user");
202 password = kvp_get(k, "password");
203 if(!password) password = "";
204 if(parse_rights(kvp_get(k, "rights"), rights, 1))
206 /* construct the expected subject. We re-encode the timestamp and the
208 byte_xasprintf(&bp, "%jx$%s$%s", t, urlencodestring(user), password);
209 /* Compute the expected signature. NB we base64 the expected signature and
210 * compare that rather than exposing our base64 parser to the cookie. */
211 if(!(sig = sign(signing_key, bp)))
213 if(!strcmp(sig, c2 + 1))
215 /* that didn't match, try the old key */
216 if(!(sig = sign(old_signing_key, bp)))
218 if(!strcmp(sig, c2 + 1))
220 /* that didn't match either */
221 disorder_error(0, "cookie signature does not match");
225 /** @brief Revoke a cookie
226 * @param cookie Cookie to revoke
228 * Further attempts to log in with @p cookie will fail.
230 void revoke_cookie(const char *cookie) {
234 /* find the cookie's expiry time */
236 when = (time_t)strtoimax(cookie, &ptr, 16);
237 /* reject bogus cookies */
242 /* make sure the revocation list exists */
244 revoked = hash_new(sizeof(time_t));
245 /* add the cookie to it; its value is the expiry time */
246 hash_add(revoked, cookie, &when, HASH_INSERT);