说服Firefox通过HTTPS发送If-Modified-Since标头

如何说服Firefox(3.0.1,如果重要的话)在HTTPS请求中发送If-Modified-Since标头？如果请求使用普通HTTP并且我的服务器尽职地尊重它,它会发送标头.但是当我使用HTTPS从同一服务器请求相同的资源时(即,只需将URL中的http://更改为https://),Firefox根本不会发送If-Modified-Since标头.这种行为是SSL规范要求的吗？

下面是一些示例HTTP和HTTPS请求/响应对,使用Live HTTP Headers Firefox扩展来提取,但有一些粗体差异:

HTTP请求/响应:

http://myserver.com:30000/scripts/site.js

GET /scripts/site.js HTTP/1.1
Host: myserver.com:30000
User-Agent: Mozilla/5.0 (...) Gecko/2008070206 Firefox/3.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
If-Modified-Since: Tue, 19 Aug 2008 15:57:30 GMT
If-None-Match: "a0501d1-300a-454d22526ae80"-gzip
Cache-Control: max-age=0

HTTP/1.x 304 Not Modified
Date: Tue, 19 Aug 2008 15:59:23 GMT
Server: Apache/2.2.8 (Unix) mod_ssl/2.2.8 OpenSSL/0.9.8
Connection: Keep-Alive
Keep-Alive: timeout=5, max=99
Etag: "a0501d1-300a-454d22526ae80"-gzip

HTTPS请求/响应:

https://myserver.com:30001/scripts/site.js

GET /scripts/site.js HTTP/1.1
Host: myserver.com:30001
User-Agent: Mozilla/5.0 (...) Gecko/2008070206 Firefox/3.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive

HTTP/1.x 200 OK
Date: Tue, 19 Aug 2008 16:00:14 GMT
Server: Apache/2.2.8 (Unix) mod_ssl/2.2.8 OpenSSL/0.9.8
Last-Modified: Tue, 19 Aug 2008 15:57:30 GMT
Etag: "a0501d1-300a-454d22526ae80"-gzip
Accept-Ranges: bytes
Content-Encoding: gzip
Content-Length: 3766
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/javascript

更新:设置browser.cache.disk_cache_ssl为true做了诀窍(这很奇怪,因为正如Nickolay指出的那样,仍有内存缓存).在响应中添加"Cache-control:public"标头也有效.谢谢!

HTTPS请求不会被缓存,因此发送If-Modified-Since没有任何意义.不缓存是一种安全预防措施.

磁盘上的非缓存是一种安全预防措施,但它似乎确实影响了If-Modified-Since行为(瞥了一眼代码).

尝试将Firefox首选项(在about:config中)设置为browser.cache.disk_cache_ssl为true.如果这有帮助,请尝试在响应中发送Cache-Control:public标头.

更新: Gecko 2.0(Firefox 4)的Firefox行为已更改 - 现在缓存了HTTPS内容.