Question

The Scenario

I have an application where we took the good old query string URL structure:

?x=1&y=2&z=3&a=4&b=5&c=6

and changed it into a path structure:

/x/1/y/2/z/3/a/4/b/5/c/6

We’re using ASP.NET MVC and (naturally) ASP.NET routing.

The Problem

The problem is that our parameters are dynamic, and there is (theoretically) no limit to the amount of parameters that we need to accommodate for.

This is all fine until we got hit by the following train:

HTTP Error 400.0 – Bad Request
ASP.NET detected invalid characters in the URL.

IIS would throw this error when our URL got past a certain length.

The Nitty Gritty

Here’s what we found out:

This is not an IIS problem

IIS does have a max path length limit, but the above error is not this.

Learn dot iis dot net
How to Use Request Filtering
Section “Filter Based on Request Limits”

If the path was too long for IIS, it would throw a 404.14, not a 400.0.

Besides, the IIS max path (and query) length are configurable:

<requestLimits


   maxAllowedContentLength="30000000"


   maxUrl="260"


   maxQueryString="25" 


              />

This is an ASP.NET Problem

After some poking around:

IIS Forums
Thread: ASP.NET 2.0 maximum URL length?
http://forums.iis.net/t/1105360.aspx

it turns out that this is an ASP.NET (well, .NET really) problem.

The heart of the matter is that, as far as I can tell, ASP.NET cannot handle paths longer than 260 characters.

The nail in the coffin in that this is confirmed by Phil the Haack himself:

Stack Overflow
ASP.NET url MAX_PATH limit
Question ID 265251

The Question

So what’s the question?

The question is, how big of a limitation is this?

For my app, it’s a deal killer. For most apps, it’s probably a non-issue.

What about disclosure? No where where ASP.NET Routing is mentioned have I ever heard a peep about this limitation. The fact that ASP.NET MVC uses ASP.NET routing makes the impact of this even bigger.

What do you think?

Answer 1

I ended up using the following in the web.config to solve this problem using Mvc2 and .Net Framework 4.0

<httpRuntime maxUrlLength="1000" relaxedUrlToFileSystemMapping="true" />