What is tolerant request parsing?

Products

• ProxySG Software - SGOS

Issue/Introduction

Understanding Tolerant HTTP Request Parsing

 

By default, the ProxySG blocks malformed HTTP requests, returning a 400 Invalid Request error. The

tolerant HTTP request parsing flag causes certain types of malformed requests to be processed instead

of being rejected.

 

By default, a header line not beginning with a <Tab> or space character must consist of a header name

(which contains no <Tab> or space characters), followed by a colon, followed by an optional value, or

an error is reported. With tolerant request parsing enabled, a request header name is allowed to

contain <Tab> or space characters, and if the request header line does not contain a colon, then the

entire line is taken as the header name.

 

A header containing one or more <Tab> or space characters, and nothing else, is considered

ambiguous. Blue Coat does not know if this is a blank continuation line or if it is the blank line that

signals the end of the header section. By default, an ambiguous blank line is illegal, and an error is

reported. With tolerant request parsing enabled, an ambiguous blank line is treated as the blank line

that signals the end of the header section.

To Enable the HTTP Tolerant Request Parsing Flag through the CLI

 

From the (config) prompt, enter the following command to enable tolerant HTTP request parsing (the default is disabled):

SGOS#(config) http tolerant-request-parsing

 

To disable HTTP tolerant request parsing, enter the following command:

SGOS#(config) http no tolerant-request-parsing