Understanding http proxies

[Cameron Simpson]

On 13Oct2012 20:43, Olive <diolu at bigfoot.com> wrote:
| I am trying to understand how to build an http proxy server in python,
| and I have found the following example:
| http://www.oki-osk.jp/esc/python/proxy/
| 
| But I do not have found an exact description of what exactly a proxy
| server is suppose to do (all references gice only the basic principe of
| proxy that I know). In the following model
| 
| Client <-> Proxy <-> Server
| 
| it seems when I read the code above that the proxy acts mostly as an
| orinary server with respect to the client except that it is supposed to
| receive the full URL instead of just the path. Am I right? Is there any
| documentation on what an http proxy is supposed to implement.

As mentioned elsewhere, in HTTP 1.0 you get a full URL in the opening
line.

In HTTP 1.1 you get the path component in the opening line and the host
part in the Host: header of the request.

Have a read of RFC2616 (which defines HTTP 1.0):

  http://tools.ietf.org/html/rfc2616

It has sections on proxies, too, outlining which they must do beyond
what a plain HTTP server must do (not much, but a few things, and there
are proxy-specific authentication fields available too):

  Proxy Servers
  http://tools.ietf.org/html/rfc2616#section-8.1.3

  Proxy Authenticate
  http://tools.ietf.org/html/rfc2616#section-14.33

Cheers,
-- 
Cameron Simpson <cs at zip.com.au>

There's two kinds of climbers...smart ones, and dead ones.      - Don Whillans