mod rewrite infinte loop problem

multiple redirections cause infinite loop

[drmoz]

Hello,

Here is what I want to do:

1. I only have ASP pages on my site but I now want people to type anypage.html and be "silently" see the anypage.asp page.

2. I also want people who go to anypage.asp to be redirected (301) to anypage.html.

I can manage to do ONE or the OTHER but if I do both I run into an infinite loop problem.

Here is the code I use:

RewriteRule ^(.*).html$ $1.asp [L]
RewriteRule ^(.*).asp$ $1.html [R=301,L]

PLEASE HELP

Thanks

[jdMorgan]

Use THE_REQUEST to break the loop:

# Redirect only direct client HTTP requests for .asp to .html
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /[^.]+\.asp\ HTTP/
RewriteRule ^([^.]+)\.asp$ http://www.example.com/$1.html [R=301,L]
#
# Internally rewrite .html requests to .asp pages
RewriteRule ^([^.]+)\.html$ $1.asp [L]

Jim

[phranque]

welcome to WebmasterWorld [webmasterworld.com], nico!

[carguy84]

Could you also just switch the order in which they appear?

RewriteRule ^(.*).asp$ $1.html [R=301,L]
RewriteRule ^(.*).html$ $1.asp [L]

I've only used ISAPI Rewrite, not familiar with mod-rewrite

[jdMorgan]

No, because the external redirect will result in a new HTTP request, so you get a loop either way.

Jim

[drmoz]

Hello,

I tried the code below.

# Redirect only direct client HTTP requests for .asp to .html
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /[^.]+\.asp\ HTTP/
RewriteRule ^([^.]+)\.asp$ http://www.example.com/$1.html [R=301,L]
#
# Internally rewrite .html requests to .asp pages
RewriteRule ^([^.]+)\.html$ $1.asp [L]

But it got me into an infinite loop again.

Thanks

[jdMorgan]

Flush your browsers cache. If that doesn't fix it, then we need to see some actual requested URL examples (with "example.com" as the domain, please).

Jim

[drmoz]

Hi,

I'll give you a precise example of what I need to do.

2 things in fact:

1. When people type http://www.example.com/mypage.html
They're "silently" (they keep seeing the mypage.html in the address bar) redirected to http://www.example.com/mypage.asp

AND

2.As I don't want the search engines to see duplicate content on my site (mypage.html and mypage.asp), I also need to permanently (301) redirect people from http://www.example.com/mypage.asp to
http://www.example.com/mypage.html

When I try to do that, I get a loop problem. The same happened with the code you gave me.

I also cleared my cache but the problem remained.

Thanks

nico

[edited by: jdMorgan at 3:56 pm (utc) on Nov. 14, 2007]
[edit reason] example.com [/edit]

[jdMorgan]

That is in fact what the code I posted does. It's code that I use on many servers.

So, either you didn't flush your browser cache completely or, like another person posting this morning, you have a caching proxy in your network path.

Another possibility is that there is another rule or scripted routine that interfering with this simple two-rule code snippet. A good way to spot this is by using the "Live HTTP Headers" add-on for Firefox and Mozilla browsers; Request the .asp URL, and watch the sequence of redirects to see if there is a redirect that is *not* produced by the mod_rewrite code, or to see if the URLs are different from what you expect. For example, if the .asp URLs have query strings attached, then the code above won't handle them, and will need to be modified.

Jim

[edited by: jdMorgan at 4:02 pm (utc) on Nov. 14, 2007]

[drmoz]

I've done what you said.

I've installed Live HTTP headers. I've also made sure the your code is the only thing on the script.

When I go to

http://www.example.com/mypage.asp

It redirects me to

http://www.example.com/mypage.html

Then it keeps redirecting me to that same page over and over again until an error message is thrown.

Thanks

nico

[edited by: jdMorgan at 2:19 pm (utc) on Nov. 15, 2007]
[edit reason] example.com [/edit]

[jdMorgan]

If the code being used is in exactly the form I showed above, with no changes except for the domain name, then this redirection loop is not happening because of that code, and you need to be looking for another 'agent' that is generating a redirect or internal rewrite, countermanding or interfering with one or both of those rewriterules. Another set of rewriterules, perhaps, or a routine in one of your scripts -- even an inconsistent domain canonicalization rule might do this.

The external redirect above can only be invoked if the client sends a request for a .asp page, while the internal rewrite is only invoked for .html page requests. So, it should be clear from examining the code itself that neither rule can redirect .html to .html, and as soon as the client requests a non-asp page, the redirect rule is disabled.

That's why I asked about flushing your cache twice; The code is very simple and works fine on dozens of my servers. Many others here have used the same code, bringing the installed base to dozens if not hundreds or even thousands more.

Jim

[phranque]

if you have access to the httpd.conf file you could try setting a higher RewriteLogLevel [httpd.apache.org].

[drmoz]

Would the code below (for mod rewrite) be the same for ISAPI rewrite?

# Redirect only direct client HTTP requests for .asp to .html
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /[^.]+\.asp\ HTTP/
RewriteRule ^([^.]+)\.asp$ http://www.example.com/$1.html [R=301,L]
#
# Internally rewrite .html requests to .asp pages
RewriteRule ^([^.]+)\.html$ $1.asp [L]

thanks

[jdMorgan]

No, the syntax is quite different for ISAPI Rewrite -- although the basic idea is the same.

Jim