HTTP Request Headers

Abstract

This document talks about http request headers in remo.
It defines the list of standard headers, it explains some of them and it links to relevant documents

Table of Contents

RFC Overview

RFC 2616, Section 5.3 defines the standard http request headers for protocol version 1.1: http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.3

Request Header Fields

request-header = Accept                   ; Section 14.1
               | Accept-Charset           ; Section 14.2
               | Accept-Encoding          ; Section 14.3
               | Accept-Language          ; Section 14.4
               | Authorization            ; Section 14.8
               | Expect                   ; Section 14.20
               | From                     ; Section 14.22
               | Host                     ; Section 14.23
               | If-Match                 ; Section 14.24
               | If-Modified-Since        ; Section 14.25
               | If-None-Match            ; Section 14.26
               | If-Range                 ; Section 14.27
               | If-Unmodified-Since      ; Section 14.28
               | Max-Forwards             ; Section 14.31
               | Proxy-Authorization      ; Section 14.34
               | Range                    ; Section 14.35
               | Referer                  ; Section 14.36
               | TE                       ; Section 14.39
               | User-Agent               ; Section 14.43

Request-header field names can be extended reliably only in combination with a change
in the protocol version. However, new or experimental header fields MAY be given the
semantics of request- header fields if all parties in the communication recognize them 
to be request-header fields. Unrecognized header fields are treated as entity-header fields. 

General Header Fields

general-header = Cache-Control            ; Section 14.9
               | Connection               ; Section 14.10
               | Date                     ; Section 14.18
               | Pragma                   ; Section 14.32
               | Trailer                  ; Section 14.40
               | Transfer-Encoding        ; Section 14.41
               | Upgrade                  ; Section 14.42
               | Via                      ; Section 14.45
               | Warning                  ; Section 14.46

General-header field names can be extended reliably only in combination 
with a change in the protocol version. However, new or experimental header 
fields may be given the semantics of general header fields if all parties 
in the communication recognize them to be general-header fields. Unrecognized
header fields are treated as entity-header fields. 

Entity Fields

entity-header  = Allow                    ; Section 14.7
               | Content-Encoding         ; Section 14.11
               | Content-Language         ; Section 14.12
               | Content-Length           ; Section 14.13
               | Content-Location         ; Section 14.14
               | Content-MD5              ; Section 14.15
               | Content-Range            ; Section 14.16
               | Content-Type             ; Section 14.17
               | Expires                  ; Section 14.21
               | Last-Modified            ; Section 14.29
               | extension-header
       extension-header = message-header

The extension-header mechanism allows additional entity-header fields to be 
defined without changing the protocol, but these fields cannot be assumed to 
be recognizable by the recipient. Unrecognized header fields SHOULD be ignored 
by the recipient and MUST be forwarded by transparent proxies. 

Remo is a security software. "We are not ignoring unrecognized header fields*. But in the future, this behaviour may change. For the time being, we consider this list of headers as fixed.

Special Stuff

Keep-Alive is a HTTP/1.0 header that is used with HTTP/1.1 with firefox for example.

Headers in remo

name	type	remo support	remo variable name
Accept-Charset	Standard Request Header	supported by default	accept_charset
Accept-Encoding	Standard Request Header	supported by default	accept_encoding
Accept-Language	Standard Request Header	supported by default	accept_language
Accept	Standard Request Header	supported by default	accept
Allow	Entity Header	unsupported
Authorization	Standard Request Header	unsupported
Cache-Control	General Header	supported by default	cache_control
Connection	General Header	supported by default	guiprefix_connection
Content-Encoding	Entity Header	unsupported
Content-Language	Entity Header	unsupported
Content-Length	Entity Header	supported by default	content_length
Content-Location	Entity Header	unsupported
Content-MD5	Entity Header	unsupported
Content-Range	Entity Header	unsupported
Content-Type	Entity Header	supported by default	content_type
Cookie	Version 0 Netscape Cookie	supported by default (as header!)	cookie
Cookie2	RFC 2965 Cookie	unsupported
Date	General Header	unsupported
Expect	Standard Request Header	unsupported
Expires	Entity Header	unsupported
From	Standard Request Header	unsupported
Host	Standard Request Header	supported by default	host
If-Match	Standard Request Header	unsupported
If-Modified-Since	Standard Request Header	unsupported
If-None-Match	Standard Request Header	unsupported
If-Range	Standard Request Header	unsupported
If-Unmodified-Since	Standard Request Header	unsupported
Keep-Alive	Old HTTP1.0 header, still in use	supported by default	keep_alive
Last-Modified	Entity Header	unsupported
Max-Forwards	Standard Request Header	unsupported
Pragma	General Header	supported by default	pragma
Proxy-Authorization	Standard Request Header	unsupported
Range	Standard Request Header	unsupported
Referer	Standard Request Header	supported by default	referer
TE	Standard Request Header	unsupported
Trailer	General Header	unsupported
Transfer-Encoding	General Header	unsupported
Upgrade	General Header	unsupported
User-Agent	Standard Request Header	supported by default	user_agent
Via	General Header	unsupported
Warning	General Header	unsupported

The remo variable name corresponds to the HTTP header name as follows:

• Capitalize first letter of every word
• Replace "_" by "-"
• Remove "guiprefix_"

The guiprefix had to be added to the fieldname "connection" because rails knows "connection" as parameter of a db item.