| 1 | /* |
| 2 | * This file is part of DisOrder. |
| 3 | * Copyright (C) 2008 Richard Kettlewell |
| 4 | * |
| 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. |
| 9 | * |
| 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 | * |
| 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/>. |
| 17 | */ |
| 18 | /** @file cgi/login.c |
| 19 | * @brief Web login support |
| 20 | */ |
| 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 | */ |
| 29 | disorder_client *dcgi_client; |
| 30 | |
| 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 | */ |
| 44 | static 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 | |
| 57 | /** @brief Login cookie */ |
| 58 | char *dcgi_cookie; |
| 59 | |
| 60 | /** @brief Set @ref dcgi_cookie */ |
| 61 | void 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 |
| 85 | disorder_error(0, "could not parse cookie field '%s'", cookie_env); |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | /** @brief Return a Cookie: header */ |
| 90 | char *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 */ |
| 125 | void 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)) { |
| 135 | dcgi_error("connect"); |
| 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 | /* |
| 144 | Local Variables: |
| 145 | c-basic-offset:2 |
| 146 | comment-column:40 |
| 147 | fill-column:79 |
| 148 | indent-tabs-mode:nil |
| 149 | End: |
| 150 | */ |