HTTP中的if-none-match和if-modified-since以及304澄清 [英] HTTP if-none-match and if-modified-since and 304 clarification in PHP
问题描述
我的问题是当我从代理/客户端请求收到两者 if-none-match和if-modified-since时,如何回复HTTP 304Not Modified。
My question is about how to reply a HTTP 304 "Not Modified" when I receive both if-none-match and if-modified-since from a proxy/client request.
来自RFC 2616第14.26节( http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26 ):
From RFC 2616 secttion 14.26 ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26 ):
如果没有实体标签匹配,那么
服务器可以执行请求的
方法,就像If-None-Match标头
字段不存在一样,但也必须
忽略请求中的任何If-Modified-Since标头
字段。也就是说,如果
没有实体标签匹配,那么服务器
不得返回304(未修改)
响应。
If none of the entity tags match, then the server MAY perform the requested method as if the If-None-Match header field did not exist, but MUST also ignore any If-Modified-Since header field(s) in the request. That is, if no entity tags match, then the server MUST NOT return a 304 (Not Modified) response.
我不确定理解这句话...
I am not sure to understand this statement...
- 如果没有实体标签匹配在PHP中,他们是否谈到
$ _ SERVER ['HTTP_IF_NONE_MATCH']
与我之前发送的ETag相比? - 如果我理解正确的话这句话,只要
$ _ SERVER ['HTTP_IF_NONE_MATCH']
中没有列出的ETag与我的ETag匹配,我就会停止所有验证并正常提供页面。
- "If none of the entity tags match" in PHP do they speak of
$_SERVER['HTTP_IF_NONE_MATCH']
vs. my ETags that I sent earlier? - If I understand correctly this statement, as soon as none of the ETags listed in
$_SERVER['HTTP_IF_NONE_MATCH']
match my ETags, I stop all verifications and serve the page normally.
任何人都可以用伪代码(或PHP代码)翻译这个RFC部分和/或回答我的2分以上?
Anyone can translate this RFC part in pseudo-code (or PHP code) and/or answer my 2 points above?
编辑1:
感谢St.Woland的回答。您(或其他任何人)可以告诉我这些6分是否正确:
EDIT 1: Thank you St.Woland for your answer. Can you (or anyone else) tell me if I'm correct on these 6 points:
-
<$ c的格式$ c> $ _ SERVER ['HTTP_IF_NONE_MATCH'] 可以是:
a)If-None-Match:xyzzy,r2d2xxxx ,c3piozzzz
a)If-None-Match: "xyzzy", "r2d2xxxx", "c3piozzzz"
b)如果 - 无匹配:xyzzy
b) If-None-Match: "xyzzy"
和NOT:
c)如果 - 无匹配:xyzzy,r2d2xxxx,c3piozzzz
c) If-None-Match: "xyzzy, r2d2xxxx, c3piozzzz"
如果!array_key_exists('HTTP_IF_NONE_MATCH',$ _SERVER)
,anyTagMatched()将返回NULL。
If !array_key_exists('HTTP_IF_NONE_MATCH', $_SERVER)
, anyTagMatched() returns NULL.
只要 $ _ SERVER ['HTTP_IF_NONE_MATCH']
中的ETag与我的文档ETag匹配,anyTagMatched()就会返回TRUE。
As soon as an ETag in $_SERVER['HTTP_IF_NONE_MATCH']
match my document ETag, anyTagMatched() returns TRUE.
如果 $ _ SERVER ['HTTP_IF_NONE_MATCH']
中没有Etags与我的文档ETag匹配, anyTagMatched()
返回FALSE。
If none of the Etags in $_SERVER['HTTP_IF_NONE_MATCH']
are matching my document ETag, anyTagMatched()
returns FALSE.
如果 $ _ SERVER ['HTTP_IF_MODIFIED_SINCE']
已设置并匹配我的文档上次修改日期 isExpired()
返回FALSE否则返回TRUE。
If $_SERVER['HTTP_IF_MODIFIED_SINCE']
is set and matches my document "last modified" date isExpired()
returns FALSE, otherwise return TRUE.
只要 anyTagMatched()
返回TRUE,我就发出304。如果anyTagMatched()返回NULL并且 isExpired()
返回FALSE我可以发出304.在任何其他情况下,我正常服务我的页面(我也发布了最新版本) date Last-Modified和ETag标题)。
As soon as anyTagMatched()
returns TRUE, I issue a 304. If anyTagMatched() returned NULL and isExpired()
returned FALSE I can issue a 304. In any other situation I serve my page as normal (I also issue the up-to-date Last-Modified and ETag headers).
推荐答案
这应该放最后(移动以获得更好的外观)。
This should be put in the end (moved for better look).
$anyTagMatched = anyTagMatched() ;
if( $anyTagMatched || ( ( null === $anyTagMatched ) && !isExpired() ) ) {
notModified() ;
}
// Output content
伪代码(需要审核):
<?php
/**
* Calculates eTag for the current resource.
*/
function calculateTag() {
}
/**
* Gets date of the most recent change.
*/
function lastChanged() {
}
/**
* TRUE if any tag matched
* FALSE if none matched
* NULL if header is not specified
*/
function anyTagMatched() {
$if_none_match = isset($_SERVER['HTTP_IF_NONE_MATCH']) ?
stripslashes($_SERVER['HTTP_IF_NONE_MATCH']) :
false ;
if( false !== $if_none_match ) {
$tags = split( ", ", $if_none_match ) ;
$myTag = calculateTag() ;
foreach( $tags as $tag ) {
if( $tag == $myTag ) return true ;
}
return false ;
}
return null ;
}
function isExpired() {
$if_modified_since = isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ?
stripslashes($_SERVER['HTTP_IF_MODIFIED_SINCE']) :
false;
if( false !== $if_modified_since ) {
// Compare time here; pseudocode.
return ( $if_modified_since < lastChanged() ) ;
}
return true ;
}
function notModified() {
header('HTTP/1.0 304 Not Modified');
exit ;
}
主要答案这里。
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