On Tue, 30 Aug 2005, Graeme Bisset wrote:
I appreciate that squid is not supposed to be HTTP/1.1 compatible but I was wondering if you knew what would be involved in adding support for this message?
This message REQUIRES HTTP/1.1. Servers MUST NOT (according to the HTTP/1.1 specifications) respond with a 1xx message in response to a HTTP/1.0 request.
But the use of 100 Continue in the thread referenced is not HTTP/1.1 compliant from what I could tell and the proposed scheme would not work even if Squid was fully HTTP/1.1 compliant.
"100 Continue" is a somewhat odd message in the HTTP protocol in that it is transport link dependent but still an end-to-end message. If any transport link in the forwarding chain is HTTP/1.0 then "100 Continue" MUST NOT be used.
What should be added to Squid (2.5 even) is the knowledge that "Expect: 100-continue" can not be met by HTTP/1.0 proxies such as Squid and the request should be immediately rejected with a "417 Expectation failed" error response.
Making the proxy fake "100 Continue" responses is not safe as it is explicitly forbidden by the HTTP specifications and may make the clients draw false conclusions about the status of their requests.
Atting support for forwarding "100 Continue" messages should not be very hard I think, but it won't get any meaningful use until Squid is HTTP/1.1 compliant and forwards requests using HTTP/1.1.
Regards Henrik
