chiark / gitweb /
Merge remote-tracking branch 'origin/branch-5.0'
[disorder] / cgi / login.c
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1/*
2 * This file is part of DisOrder.
3 * Copyright (C) 2008 Richard Kettlewell
4 *
e7eb3a27 5 * This program is free software: you can redistribute it and/or modify
1e97629d 6 * it under the terms of the GNU General Public License as published by
e7eb3a27 7 * the Free Software Foundation, either version 3 of the License, or
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8 * (at your option) any later version.
9 *
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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.
14 *
1e97629d 15 * You should have received a copy of the GNU General Public License
e7eb3a27 16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
1e97629d 17 */
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18/** @file cgi/login.c
19 * @brief Web login support
20 */
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21#include "disorder-cgi.h"
22
23/** @brief Client used by CGI
24 *
25 * The caller should arrange for this to be created before any of
26 * these expansions are used (if it cannot connect then it's safe to
27 * leave it as NULL).
28 */
29disorder_client *dcgi_client;
30
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31/** @brief Return true if @p a is better than @p b
32 *
33 * NB. We don't bother checking if the path is right, we merely check for the
34 * longest path. This isn't a security hole: if the browser wants to send us
35 * bad cookies it's quite capable of sending just the right path anyway. The
36 * point of choosing the longest path is to avoid using a cookie set by another
37 * CGI script which shares a path prefix with us, which would allow it to
38 * maliciously log users out.
39 *
40 * Such a script could still "maliciously" log someone in, if it had acquired a
41 * suitable cookie. But it could just log in directly if it had that, so there
42 * is no obvious vulnerability here either.
43 */
44static int better_cookie(const struct cookie *a, const struct cookie *b) {
45 if(a->path && b->path)
46 /* If both have a path then the one with the longest path is best */
47 return strlen(a->path) > strlen(b->path);
48 else if(a->path)
49 /* If only @p a has a path then it is better */
50 return 1;
51 else
52 /* If neither have a path, or if only @p b has a path, then @p b is
53 * better */
54 return 0;
55}
56
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57/** @brief Login cookie */
58char *dcgi_cookie;
59
59cf25c4 60/** @brief Set @ref dcgi_cookie */
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61void dcgi_get_cookie(void) {
62 const char *cookie_env;
63 int n, best_cookie;
64 struct cookiedata cd;
65
66 /* See if there's a cookie */
67 cookie_env = getenv("HTTP_COOKIE");
68 if(cookie_env) {
69 /* This will be an HTTP header */
70 if(!parse_cookie(cookie_env, &cd)) {
71 /* Pick the best available cookie from all those offered */
72 best_cookie = -1;
73 for(n = 0; n < cd.ncookies; ++n) {
74 /* Is this the right cookie? */
75 if(strcmp(cd.cookies[n].name, "disorder"))
76 continue;
77 /* Is it better than anything we've seen so far? */
78 if(best_cookie < 0
79 || better_cookie(&cd.cookies[n], &cd.cookies[best_cookie]))
80 best_cookie = n;
81 }
82 if(best_cookie != -1)
83 dcgi_cookie = cd.cookies[best_cookie].value;
84 } else
2e9ba080 85 disorder_error(0, "could not parse cookie field '%s'", cookie_env);
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86 }
87}
88
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89/** @brief Return a Cookie: header */
90char *dcgi_cookie_header(void) {
91 struct dynstr d[1];
92 struct url u;
93 char *s;
94
95 memset(&u, 0, sizeof u);
96 dynstr_init(d);
97 parse_url(config->url, &u);
98 if(dcgi_cookie) {
99 dynstr_append_string(d, "disorder=");
100 dynstr_append_string(d, dcgi_cookie);
101 } else {
102 /* Force browser to discard cookie */
103 dynstr_append_string(d, "disorder=none;Max-Age=0");
104 }
105 if(u.path) {
106 /* The default domain matches the request host, so we need not override
107 * that. But the default path only goes up to the rightmost /, which would
108 * cause the browser to expose the cookie to other CGI programs on the same
109 * web server. */
110 dynstr_append_string(d, ";Version=1;Path=");
111 /* Formally we are supposed to quote the path, since it invariably has a
112 * slash in it. However Safari does not parse quoted paths correctly, so
113 * this won't work. Fortunately nothing else seems to care about proper
114 * quoting of paths, so in practice we get with it. (See also
115 * parse_cookie() where we are liberal about cookie paths on the way back
116 * in.) */
117 dynstr_append_string(d, u.path);
118 }
119 dynstr_terminate(d);
120 byte_xasprintf(&s, "Set-Cookie: %s", d->vec);
121 return s;
122}
123
124/** @brief Log in as the current user or guest if none */
125void dcgi_login(void) {
126 /* Junk old data */
127 dcgi_lookup_reset();
128 /* Junk the old connection if there is one */
129 if(dcgi_client)
130 disorder_close(dcgi_client);
131 /* Create a new connection */
132 dcgi_client = disorder_new(0);
133 /* Reconnect */
134 if(disorder_connect_cookie(dcgi_client, dcgi_cookie)) {
0d0253c9 135 dcgi_error("connect");
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136 exit(0);
137 }
138 /* If there was a cookie but it went bad, we forget it */
139 if(dcgi_cookie && !strcmp(disorder_user(dcgi_client), "guest"))
140 dcgi_cookie = 0;
141}
142
143/*
144Local Variables:
145c-basic-offset:2
146comment-column:40
147fill-column:79
148indent-tabs-mode:nil
149End:
150*/