WinInet discards some HTTP response headers

[GoogleCodeExporter]

I learned today while working on Page Speed integration in WebPageTest that 
WinInet discards some HTTP response headers, including: Set-Cookie, 
Last-Modified, Server, Date, Expires, Connection, Proxy-Connection, Via, Age, 
Cache-Control, and Accept-Ranges. WinInet will also remove Content-Encoding  if 
it is instructed to decode responses. Some of these headers are used to 
populate the INTERNET_CACHE_ENTRY_INFO structure associated with the WinInet 
cache entry. The ICEI is used to reconstruct Last-Modified and Expires headers. 
Thus the headers that are not recoverable are:

Set-Cookie
Server
Date
Connection
Proxy-Connection
Via
Age
Cache-Control (excluding max-age, which will be converted to an Expires header)
Accept-Ranges
Content-Encoding

Of these, the headers that are of concern to Page Speed are the Date, 
Content-Encoding, and Cache-Control headers (other than the max-age directive). 
The specific Cache-Control headers we care about are must-revalidate, no-store, 
and no-cache. We need to run tests to determine if these headers leave any 
other indicators in the ICEI structure, or else modify the logic in 
resource_util.cc to understand when these directives may be missing, and fail 
gracefully.

Original issue reported on code.google.com by bmcqu...@google.com on 12 Aug 2010 at 7:54