PHP - Detect gzip server response

I'm using curl to fetch a webpage, I need to detect if the response is gzip or not.

This works perfectly fine if Content-Encoding is specified in the response headers, but some servers instead return "Transfer-Encoding": "Chunked开发者_Go百科" and no Content-Encoding header.

Is there any way to detect gzip or get the raw (encoded) server response?

I tried looking at curl_getinfo but the content_encoding isn't specified either.

Thanks.

You can check if response starts with gzip magic numbers, specifically 1f 8b.

Is there any way to detect gzip

Yes. You can use cURLs Header functions. For example you can define an function, which handles the header responses. Use curl_setopt()with the CURLOPT_HEADERFUNCTION option. Or write it to an file (which you have created with fopen()) with the CURLOPT_WRITEHEADER option.

There may are more options you could use. Look out the possibilities at the curl_setopt() manual. The header you are looking for have the name: Content-Encoding.

If you have the output in a file, you could also use PHPs finfo with some of its predefined constants. Or mime_content_type() (DEPRECATED!) if finfo is not available to you.

[...] or get the raw (encoded) server response?

Yes. You can specify the accept-encoding header. The value you are look for is identity. So you can send:

Accept-Encoding: identity

May have look to the HTTP/1.1 RFC To get an unencoded/uncompressed output (for example to directly write it into a file). Use CURLOPT_ENCODING for this purpose. You can set it also with *curl_setopt*.

You can either issue a separate HEAD request:

CURLOPT_HEADER => true
CURLOPT_NOBODY => true

Or request the header to be prefixed to your original request:

CURLOPT_HEADER => true

But, if you just want to get the (decoded) HTML, you can use:

CURLOPT_ENCODING => ''

And CURL will automatically negotiate with the server and decode it for you.