The call to apr_explode_localtime() in mod_log_config is one of the more (9e5cfb8f) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP Apache Httpd

CHANGES

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		Changes with Apache 2.0.26-dev

		*) Cache apr_explode_localtime() value for 15 seconds.
		[Brian Pane <bpane@pacbell.net>]

		*) Fix mod_include to not return ETag or Last-Modified headers.
		[Ian Holsman <ianh@cnet.com>]

include/util_time.h

0 → 100644

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		/* ====================================================================
		* The Apache Software License, Version 1.1
		*
		* Copyright (c) 2001 The Apache Software Foundation. All rights
		* reserved.
		*
		* Redistribution and use in source and binary forms, with or without
		* modification, are permitted provided that the following conditions
		* are met:
		*
		* 1. Redistributions of source code must retain the above copyright
		* notice, this list of conditions and the following disclaimer.
		*
		* 2. Redistributions in binary form must reproduce the above copyright
		* notice, this list of conditions and the following disclaimer in
		* the documentation and/or other materials provided with the
		* distribution.
		*
		* 3. The end-user documentation included with the redistribution,
		* if any, must include the following acknowledgment:
		* "This product includes software developed by the
		* Apache Software Foundation (http://www.apache.org/)."
		* Alternately, this acknowledgment may appear in the software itself,
		* if and wherever such third-party acknowledgments normally appear.
		*
		* 4. The names "Apache" and "Apache Software Foundation" must
		* not be used to endorse or promote products derived from this
		* software without prior written permission. For written
		* permission, please contact apache@apache.org.
		*
		* 5. Products derived from this software may not be called "Apache",
		* nor may "Apache" appear in their name, without prior written
		* permission of the Apache Software Foundation.
		*
		* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
		* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
		* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
		* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
		* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
		* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
		* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
		* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
		* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
		* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
		* SUCH DAMAGE.
		* ====================================================================
		*
		* This software consists of voluntary contributions made by many
		* individuals on behalf of the Apache Software Foundation. For more
		* information on the Apache Software Foundation, please see
		* <http://www.apache.org/>.
		*
		*/

		#ifndef APACHE_UTIL_TIME_H
		#define APACHE_UTIL_TIME_H

		#include "apr.h"
		#include "apr_time.h"
		#include "httpd.h"

		#ifdef __cplusplus
		extern "C" {
		#endif

		/**
		* @package Apache date/time handling functions
		*/

		/* Maximum delta from the current time, in seconds, for a past time
		* to qualify as "recent" for use in the ap_explode_recent_*() functions:
		*/
		#define AP_TIME_RECENT_THRESHOLD 15

		/**
		* convert a recent time to its human readable components in local timezone
		* @param tm the exploded time
		* @param t the time to explode: MUST be within the last
		* AP_TIME_RECENT_THRESHOLD seconds
		* @note This is a faster alternative to apr_explode_localtime that uses
		* a cache of pre-exploded time structures. It is useful for things
		* that need to explode the current time multiple times per second,
		* like loggers.
		* @return APR_SUCCESS iff successful
		* @deffunc apr_status_t ap_explode_recent_localtime(apr_exploded_time_t *tm, apr_time_t t);
		*/
		AP_DECLARE(apr_status_t) ap_explode_recent_localtime(apr_exploded_time_t *tm,
		apr_time_t t);

		/**
		* convert a recent time to its human readable components in GMT timezone
		* @param tm the exploded time
		* @param t the time to explode: MUST be within the last
		* AP_TIME_RECENT_THRESHOLD seconds
		* @note This is a faster alternative to apr_explode_gmt that uses
		* a cache of pre-exploded time structures. It is useful for things
		* that need to explode the current time multiple times per second,
		* like loggers.
		* @return APR_SUCCESS iff successful
		* @deffunc apr_status_t ap_explode_recent_gmt(apr_exploded_time_t *tm, apr_time_t t);
		*/
		AP_DECLARE(apr_status_t) ap_explode_recent_gmt(apr_exploded_time_t *tm,
		apr_time_t t);


		#ifdef __cplusplus
		}
		#endif

		#endif /* !APACHE_UTIL_TIME_H */

modules/loggers/mod_log_config.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -196,6 +196,7 @@
		#include "http_core.h" /* For REMOTE_NAME */
		#include "http_log.h"
		#include "http_protocol.h"
		#include "util_time.h"

		#if APR_HAVE_UNISTD_H
		#include <unistd.h>
		@@ -463,9 +464,9 @@ static const char log_request_time(request_rec r, char *a)
		a problem with this, you can set the define. -djg
		*/
		#ifdef I_INSIST_ON_EXTRA_CYCLES_FOR_CLF_COMPLIANCE
		apr_explode_localtime(&xt, apr_time_now());
		ap_explode_recent_localtime(&xt, apr_time_now());
		#else
		apr_explode_localtime(&xt, r->request_time);
		ap_explode_recent_localtime(&xt, r->request_time);
		#endif
		if (a && a) { / Custom format */
		apr_strftime(tstr, &retcode, MAX_STRING_LEN, a, &xt);

server/Makefile.in

+3 −3

Original line number	Diff line number	Diff line
		@@ -11,7 +11,7 @@ LTLIBRARY_NAME = libmain.la
		LTLIBRARY_SOURCES = \
		test_char.h \
		config.c log.c main.c vhost.c util.c \
		util_script.c util_md5.c util_cfgtree.c util_ebcdic.c \
		util_script.c util_md5.c util_cfgtree.c util_ebcdic.c util_time.c \
		rfc1413.c connection.c listen.c \
		mpm_common.c util_charset.c util_debug.c util_xml.c \
		util_filter.c exports.c buildmark.c scoreboard.c \

server/util_time.c

0 → 100644

+175 −0

Original line number	Diff line number	Diff line
		/* ====================================================================
		* The Apache Software License, Version 1.1
		*
		* Copyright (c) 2001 The Apache Software Foundation. All rights
		* reserved.
		*
		* Redistribution and use in source and binary forms, with or without
		* modification, are permitted provided that the following conditions
		* are met:
		*
		* 1. Redistributions of source code must retain the above copyright
		* notice, this list of conditions and the following disclaimer.
		*
		* 2. Redistributions in binary form must reproduce the above copyright
		* notice, this list of conditions and the following disclaimer in
		* the documentation and/or other materials provided with the
		* distribution.
		*
		* 3. The end-user documentation included with the redistribution,
		* if any, must include the following acknowledgment:
		* "This product includes software developed by the
		* Apache Software Foundation (http://www.apache.org/)."
		* Alternately, this acknowledgment may appear in the software itself,
		* if and wherever such third-party acknowledgments normally appear.
		*
		* 4. The names "Apache" and "Apache Software Foundation" must
		* not be used to endorse or promote products derived from this
		* software without prior written permission. For written
		* permission, please contact apache@apache.org.
		*
		* 5. Products derived from this software may not be called "Apache",
		* nor may "Apache" appear in their name, without prior written
		* permission of the Apache Software Foundation.
		*
		* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
		* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
		* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
		* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
		* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
		* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
		* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
		* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
		* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
		* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
		* SUCH DAMAGE.
		* ====================================================================
		*
		* This software consists of voluntary contributions made by many
		* individuals on behalf of the Apache Software Foundation. For more
		* information on the Apache Software Foundation, please see
		* <http://www.apache.org/>.
		*
		*/

		#include "util_time.h"

		/* Cache for exploded values of recent timestamps
		*/

		struct exploded_time_cache_element {
		apr_int64_t t;
		apr_exploded_time_t xt;
		apr_int64_t t_validate; /* please see comments in cached_explode() */
		};

		/* the "+ 1" is for the current second: */
		#define TIME_CACHE_SIZE (AP_TIME_RECENT_THRESHOLD + 1)

		static struct exploded_time_cache_element exploded_cache_localtime[TIME_CACHE_SIZE];
		static struct exploded_time_cache_element exploded_cache_gmt[TIME_CACHE_SIZE];


		static apr_status_t cached_explode(apr_exploded_time_t *xt, apr_time_t t,
		struct exploded_time_cache_element *cache,
		int use_gmt)
		{
		apr_int64_t seconds = t / APR_USEC_PER_SEC;
		struct exploded_time_cache_element *cache_element =
		&(cache[seconds % TIME_CACHE_SIZE]);
		struct exploded_time_cache_element cache_element_snapshot;

		/* The cache is implemented as a ring buffer. Each second,
		* it uses a different element in the buffer. The timestamp
		* in the element indicates whether the element contains the
		* exploded time for the current second (vs the time
		* 'now - AP_TIME_RECENT_THRESHOLD' seconds ago). If the
		* cached value is for the current time, we use it. Otherwise,
		* we compute the apr_exploded_time_t and store it in this
		* cache element. Note that the timestamp in the cache
		* element is updated only after the exploded time. Thus
		* if two threads hit this cache element simultaneously
		* at the start of a new second, they'll both explode the
		* time and store it. I.e., the writers will collide, but
		* they'll be writing the same value.
		*/
		if (cache_element->t >= seconds) {
		/* There is an intentional race condition in this design:
		* in a multithreaded app, one thread might be reading
		* from this cache_element to resolve a timestamp from
		* TIME_CACHE_SIZE seconds ago at the same time that
		* another thread is copying the exploded form of the
		* current time into the same cache_element. (I.e., the
		* first thread might hit this element of the ring buffer
		* just as the element is being recycled.) This can
		* also happen at the start of a new second, if a
		* reader accesses the cache_element after a writer
		* has updated cache_element.t but before the writer
		* has finished updating the whole cache_element.
		*
		* Rather than trying to prevent this race condition
		* with locks, we allow it to happen and then detect
		* and correct it. The detection works like this:
		* Step 1: Take a "snapshot" of the cache element by
		* copying it into a temporary buffer.
		* Step 2: Check whether the snapshot contains consistent
		* data: the timestamps at the start and end of
		* the cache_element should both match the 'seconds'
		* value that we computed from the input time.
		* If these three don't match, then the snapshot
		* shows the cache_element in the middle of an
		* update, and its contents are invalid.
		* Step 3: If the snapshot is valid, use it. Otherwise,
		* just give up on the cache and explode the
		* input time.
		*/
		memcpy(&cache_element_snapshot, cache_element,
		sizeof(struct exploded_time_cache_element));
		if ((seconds != cache_element_snapshot.t) \|\|
		(seconds != cache_element_snapshot.t_validate)) {
		/* Invalid snapshot */
		if (use_gmt) {
		return apr_explode_gmt(xt, t);
		}
		else {
		return apr_explode_localtime(xt, t);
		}
		}
		else {
		/* Valid snapshot */
		memcpy(xt, &(cache_element_snapshot.xt),
		sizeof(apr_exploded_time_t));
		}
		}
		else {
		apr_status_t r;
		if (use_gmt) {
		r = apr_explode_gmt(xt, t);
		}
		else {
		r = apr_explode_localtime(xt, t);
		}
		if (!APR_STATUS_IS_SUCCESS(r)) {
		return r;
		}
		cache_element->t = seconds;
		memcpy(&(cache_element->xt), xt, sizeof(apr_exploded_time_t));
		cache_element->t_validate = seconds;
		}
		xt->tm_usec = t % APR_USEC_PER_SEC;
		return APR_SUCCESS;
		}


		AP_DECLARE(apr_status_t) ap_explode_recent_localtime(apr_exploded_time_t * tm,
		apr_time_t t)
		{
		return cached_explode(tm, t, exploded_cache_localtime, 0);
		}

		AP_DECLARE(apr_status_t) ap_explode_recent_gmt(apr_exploded_time_t * tm,
		apr_time_t t)
		{
		return cached_explode(tm, t, exploded_cache_gmt, 1);
		}