mirror of https://github.com/acanas/swad-core.git
117 lines
4.3 KiB
C
117 lines
4.3 KiB
C
// swad_firewall.c: firewall to mitigate denial of service attacks
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/*
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SWAD (Shared Workspace At a Distance),
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is a web platform developed at the University of Granada (Spain),
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and used to support university teaching.
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This file is part of SWAD core.
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Copyright (C) 1999-2023 Antonio Cañas Vargas
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*****************************************************************************/
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/********************************* Headers ***********************************/
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/*****************************************************************************/
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#include <stdlib.h> // For exit
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#include "swad_database.h"
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#include "swad_firewall.h"
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#include "swad_firewall_database.h"
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/*****************************************************************************/
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/****************************** Private prototypes ***************************/
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/*****************************************************************************/
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static void Fir_WriteHTML (const char *Title,const char *H1);
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/*****************************************************************************/
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/*************************** Check if IP is banned ***************************/
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/*****************************************************************************/
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void Fir_CheckFirewallAndExitIfBanned (void)
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{
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unsigned NumCurrentBans;
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/***** Get number of current bans from database *****/
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NumCurrentBans = Fir_DB_GetNumBansIP ();
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/***** Exit with status 403 if banned *****/
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/* RFC 6585 suggests "403 Forbidden", according to
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https://stackoverflow.com/questions/7447283/proper-http-status-to-return-for-hacking-attempts
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https://tools.ietf.org/html/rfc2616#section-10.4.4 */
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if (NumCurrentBans)
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{
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/* Return status 403 Forbidden */
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fprintf (stdout,"Content-Type: text/html; charset=windows-1252\n"
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"Status: 403\r\n\r\n");
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Fir_WriteHTML ("Forbidden","You are temporarily banned");
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/* Close database connection and exit */
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DB_CloseDBConnection ();
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exit (0);
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}
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}
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/*****************************************************************************/
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/**************** Check if too many connections from this IP *****************/
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/*****************************************************************************/
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void Fir_CheckFirewallAndExitIfTooManyRequests (void)
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{
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unsigned NumClicks;
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/***** Get number of clicks from database *****/
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NumClicks = Fir_DB_GetNumClicksFromLog ();
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/***** Exit with status 429 if too many connections *****/
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/* RFC 6585 suggests "429 Too Many Requests", according to
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https://stackoverflow.com/questions/46664695/whats-the-correct-http-response-code-to-return-for-denial-of-service-dos-atta
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https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/429 */
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if (NumClicks > Fw_MAX_CLICKS_IN_INTERVAL)
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{
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/* Ban this IP */
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Fir_DB_BanIP ();
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/* Return status 429 Too Many Requests */
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fprintf (stdout,"Content-Type: text/html; charset=windows-1252\n"
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"Retry-After: %lu\n"
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"Status: 429\r\n\r\n",
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(unsigned long) Fw_TIME_BANNED);
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Fir_WriteHTML ("Too Many Requests","Please stop that");
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/* Close database connection and exit */
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DB_CloseDBConnection ();
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exit (0);
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}
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}
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/*****************************************************************************/
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/********************************* Ban an IP *********************************/
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/*****************************************************************************/
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static void Fir_WriteHTML (const char *Title,const char *H1)
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{
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fprintf (stdout,"<html>"
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"<head>"
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"<title>%s</title>"
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"</head>"
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"<body>"
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"<h1>%s</h1>"
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"</body>"
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"</html>\n",
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Title,H1);
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}
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