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Problem: The value of a Response Header is greater than 8K and always clipped.

Server Config:

  • Apache 2.4.16-x64 with mod_proxy and mod_proxy_http / Running on Windows Server 2012

Httpd.conf:

  • LimitRequestFieldSize 65536
  • LimitRequestLine 65536
  • ProxyIOBufferSize 65536

Virtual Host conf:

When calling the backend directly the Header Value comes back ok (appr. 30K) Through the proxy its always clipped after 8K.

LimitRequestFieldSize etc. should work in 2.4.16 out of the Box without recompiling. Decreasing the Value shows an effect (HTTP/1.1 414 Request-URI Too Large..)

Can anybody provide fresh ideas or key words to search further with?

Thanks in advance:)

Matthias

Euro
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  • [`LimitRequestFieldSize`](http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize) and [`LimitRequestLine`](http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestline) are for **request** headers, am I misunderstanding the question when I read it as being about **response** headers? – Håkan Lindqvist Aug 08 '15 at 14:11
  • I thought so too but then i have seen some posts mentioning the attributes affecting all headers. And in some cases after using them in the config the problems disappeared so i decided to try them out.. – Euro Aug 08 '15 at 14:33
  • Why is your application sending such a long header? – Michael Hampton Aug 08 '15 at 18:12

1 Answers1

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I looked at this problem last month in Apache, and it is a mod_proxy specific limitation in all releases.

covener
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  • After more reading this limititation seems to reside in the file proxy_http.c: The user space buffer size for mod_proxy seems to be fixed at 8 KB, but changing it is just a matter of replacing HUGE_STRING_LEN with something else in src/modules/proxy/proxy_http.c under the Apache source distribution.Source: I will try to change that value and report back... – Euro Aug 10 '15 at 09:15
  • Changed the inner workings of the application so no test if compiling mod_proxy with different buffer size would have fixed the problem. – Euro Aug 10 '15 at 16:21