/* tinyproxy - A fast light-weight HTTP proxy
 * Copyright (C) 1999-2005 Robert James Kaes <rjkaes@users.sourceforge.net>
 *
 * 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
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* Allow tinyproxy to be used as a reverse proxy. */

#include "tinyproxy.h"
#include "reverse-proxy.h"

#include "conns.h"
#include "heap.h"
#include "html-error.h"
#include "log.h"

/*
 * Add entry to the reversepath list
 */
void
reversepath_add (const char *path, const char *url)
{
  struct reversepath *reverse;

  if (url == NULL)
    {
      log_message (LOG_WARNING, "Illegal reverse proxy rule: missing url");
      return;
    }

  if (!strstr (url, "://"))
    {
      log_message (LOG_WARNING,
		   "Skipping reverse proxy rule: '%s' is not a valid url",
		   url);
      return;
    }

  if (path && *path != '/')
    {
      log_message (LOG_WARNING,
		   "Skipping reverse proxy rule: path '%s' doesn't start with a /",
		   path);
      return;
    }

  if (!(reverse = safemalloc (sizeof (struct reversepath))))
    {
      log_message (LOG_ERR, "Unable to allocate memory in reversepath_add()");
      return;
    }

  if (!path)
    reverse->path = safestrdup ("/");
  else
    reverse->path = safestrdup (path);

  reverse->url = safestrdup (url);

  reverse->next = config.reversepath_list;
  config.reversepath_list = reverse;

  log_message (LOG_INFO,
	       "Added reverse proxy rule: %s -> %s", reverse->path,
	       reverse->url);
}

/*
 * Check if a request url is in the reversepath list
 */
struct reversepath *
reversepath_get (char *url)
{
  struct reversepath *reverse = config.reversepath_list;

  while (reverse)
    {
      if (strstr (url, reverse->path) == url)
	return reverse;

      reverse = reverse->next;
    }

  return NULL;
}

/*
 * Rewrite the URL for reverse proxying.
 */
char *
reverse_rewrite_url (struct conn_s *connptr, hashmap_t hashofheaders,
		     char *url)
{
  char *rewrite_url = NULL;
  char *cookie = NULL;
  char *cookieval;
  struct reversepath *reverse;

  /* Reverse requests always start with a slash */
  if (*url == '/')
    {
      /* First try locating the reverse mapping by request url */
      reverse = reversepath_get (url);
      if (reverse)
	{
	  rewrite_url = safemalloc (strlen (url) + strlen (reverse->url) + 1);
	  strcpy (rewrite_url, reverse->url);
	  strcat (rewrite_url, url + strlen (reverse->path));
	}
      else if (config.reversemagic
	       && hashmap_entry_by_key (hashofheaders,
					"cookie", (void **) &cookie) > 0)
	{

	  /* No match - try the magical tracking cookie next */
	  if ((cookieval = strstr (cookie, REVERSE_COOKIE "="))
	      && (reverse =
		  reversepath_get (cookieval + strlen (REVERSE_COOKIE) + 1)))
	    {

	      rewrite_url = safemalloc (strlen (url) +
					strlen (reverse->url) + 1);
	      strcpy (rewrite_url, reverse->url);
	      strcat (rewrite_url, url + 1);

	      log_message (LOG_INFO,
			   "Magical tracking cookie says: %s", reverse->path);
	    }
	}
    }

  /* Forward proxy support off and no reverse path match found */
  if (config.reverseonly && !rewrite_url)
    {
      log_message (LOG_ERR, "Bad request");
      indicate_http_error (connptr, 400, "Bad Request",
			   "detail",
			   "Request has an invalid URL", "url", url, NULL);
      return NULL;
    }

  log_message (LOG_CONN, "Rewriting URL: %s -> %s", url, rewrite_url);

  /* Store reverse path so that the magical tracking cookie can be set */
  if (config.reversemagic)
    connptr->reversepath = safestrdup (reverse->path);

  return rewrite_url;
}