X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/6d2d327ca57fefaddceba10eb323451f8150e95d..15091f766f1e8c380d2a7f752c387a2cecaf5bb1:/server/cgimain.c

diff --git a/server/cgimain.c b/server/cgimain.c
index 231ece1..4a37c52 100644
--- a/server/cgimain.c
+++ b/server/cgimain.c
@@ -1,6 +1,6 @@
 /*
  * This file is part of DisOrder.
- * Copyright (C) 2004, 2005 Richard Kettlewell
+ * Copyright (C) 2004, 2005, 2007, 2008 Richard Kettlewell
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -17,6 +17,9 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  * USA
  */
+/** @file server/cgimain.c
+ * @brief DisOrder CGI
+ */
 
 #include <config.h>
 #include "types.h"
@@ -32,42 +35,122 @@
 
 #include "client.h"
 #include "sink.h"
-#include "cgi.h"
-#include "dcgi.h"
+#include "server-cgi.h"
 #include "mem.h"
 #include "log.h"
 #include "configuration.h"
 #include "disorder.h"
 #include "api-client.h"
-  
+#include "mime.h"
+#include "printf.h"
+#include "dcgi.h"
+#include "url.h"
+
+#include "macros.h"
+#include "macros-disorder.h"
+
+/** @brief Return true if @p a is better than @p b
+ *
+ * NB. We don't bother checking if the path is right, we merely check for the
+ * longest path.  This isn't a security hole: if the browser wants to send us
+ * bad cookies it's quite capable of sending just the right path anyway.  The
+ * point of choosing the longest path is to avoid using a cookie set by another
+ * CGI script which shares a path prefix with us, which would allow it to
+ * maliciously log users out.
+ *
+ * Such a script could still "maliciously" log someone in, if it had acquired a
+ * suitable cookie.  But it could just log in directly if it had that, so there
+ * is no obvious vulnerability here either.
+ */
+static int better_cookie(const struct cookie *a, const struct cookie *b) {
+  if(a->path && b->path)
+    /* If both have a path then the one with the longest path is best */
+    return strlen(a->path) > strlen(b->path);
+  else if(a->path)
+    /* If only @p a has a path then it is better */
+    return 1;
+  else
+    /* If neither have a path, or if only @p b has a path, then @p b is
+     * better */
+    return 0;
+}
+
 int main(int argc, char **argv) {
-  const char *user, *conf;
+  const char *cookie_env, *conf;
   dcgi_global g;
   dcgi_state s;
   cgi_sink output;
+  int n, best_cookie;
+  struct cookiedata cd;
 
-  if(argc > 0) progname = argv[0];
+  if(argc > 0)
+    progname = argv[0];
+  /* RFC 3875 s8.2 recommends rejecting PATH_INFO if we don't make use of
+   * it. */
+  if(getenv("PATH_INFO")) {
+    /* TODO it might be nice to link back to the right place... */
+    printf("Content-Type: text/html\n");
+    printf("Status: 404\n");
+    printf("\n");
+    printf("<p>Sorry, PATH_INFO not supported.</p>\n");
+    exit(0);
+  }
   cgi_parse();
-  if((conf = getenv("DISORDER_CONFIG"))) configfile = xstrdup(conf);
-  if(getenv("DISORDER_DEBUG")) debugging = 1;
-  if(config_read()) exit(EXIT_FAILURE);
+  /* We allow various things to be overridden from the environment.  This is
+   * intended for debugging and is not a documented feature. */
+  if((conf = getenv("DISORDER_CONFIG")))
+    configfile = xstrdup(conf);
+  if(getenv("DISORDER_DEBUG"))
+    debugging = 1;
+  if(config_read(0))
+    exit(EXIT_FAILURE);
+  /* Figure out our URL.  This can still be overridden from the config file if
+   * necessary but it shouldn't be necessary in ordinary installations. */
+  if(!config->url)
+    config->url = infer_url();
   memset(&g, 0, sizeof g);
   memset(&s, 0, sizeof s);
   s.g = &g;
   g.client = disorder_get_client();
   output.quote = 1;
-  output.sink = sink_stdio("stdout", stdout); 
-  if(!(user = getenv("REMOTE_USER"))) fatal(0, "REMOTE_USER is not set");
-  if(disorder_connect(g.client)) {
-    disorder_cgi_error(&output, &s, "connect");
-    return 0;
-  }
-  if(disorder_become(g.client, user)) {
-    disorder_cgi_error(&output, &s, "become");
-    return 0;
+  output.sink = sink_stdio("stdout", stdout);
+  /* See if there's a cookie */
+  cookie_env = getenv("HTTP_COOKIE");
+  if(cookie_env) {
+    /* This will be an HTTP header */
+    if(!parse_cookie(cookie_env, &cd)) {
+      /* Pick the best available cookie from all those offered */
+      best_cookie = -1;
+      for(n = 0; n < cd.ncookies; ++n) {
+	/* Is this the right cookie? */
+	if(strcmp(cd.cookies[n].name, "disorder"))
+	  continue;
+	/* Is it better than anything we've seen so far? */
+	if(best_cookie < 0
+	   || better_cookie(&cd.cookies[n], &cd.cookies[best_cookie]))
+	  best_cookie = n;
+      }
+      if(best_cookie != -1)
+	login_cookie = cd.cookies[best_cookie].value;
+    } else
+      error(0, "could not parse cookie field '%s'", cookie_env);
   }
+  /* Register expansions */
+  mx_register_builtin();
+  register_disorder_expansions();
+  /* Update search path.  We look in the config directory first and the data
+   * directory second, so that the latter overrides the former. */
+  mx_search_path(pkgconfdir);
+  mx_search_path(pkgdatadir);
+  /* Create the initial connection, trying the cookie if we found a suitable
+   * one. */
+  disorder_cgi_login(&s, &output);
+  /* The main program... */
   disorder_cgi(&output, &s);
-  if(fclose(stdout) < 0) fatal(errno, "error closing stdout");
+  /* In practice if a write fails that probably means the web server went away,
+   * but we log it anyway. */
+  if(fclose(stdout) < 0)
+    fatal(errno, "error closing stdout");
   return 0;
 }
 
@@ -75,5 +158,7 @@ int main(int argc, char **argv) {
 Local Variables:
 c-basic-offset:2
 comment-column:40
+fill-column:79
+indent-tabs-mode:nil
 End:
 */