Re: Taylor Francis eBooks

Hi Andreas,

Presumably this isn't a problem in this case if you don't need to proxy this host on AWS, in fact you don't want to if access is prevented by CORS. But if there was a long FQDN that needed proxying then I think you could shorten the proxied hostname using ProxyHostnameEdit:
https://help.oclc.org/Library_Management/EZproxy/Configure_resources/ProxyHostnameEdit

Cheers,
Laurence

Laurence Lockton
University of Bath
UK
-----Original Message-----
From: EZproxy List <[email protected]> On Behalf Of Bohne-Lang, Andreas
Sent: 10 October 2019 06:41
To: [email protected]
Subject: Re: [EZPROXY-L] Taylor Francis eBooks

Dear Andrew,

thank you for your explanation! You are right and I think it could be a general problem for EZProxy.

Do you know if EZProxy can shorten parts of the url? Maybe by a md5-hash code?

Example from our case:

s3-euw1-ap-pe-ws4-capi2-distribution-p.s3-eu-west-1.amazonaws.com is valid.

(Better view with # a seperator: 
s3-euw1-ap-pe-ws4-capi2-distribution-p#s3-eu-west-1#amazonaws#com)


But in EZProxy convert this into:

s3-euw1-ap-pe-ws4-capi2-distribution-p-s3-eu-west-1-amazonaws-com


and with EZProxy it looks like this:

s3-euw1-ap-pe-ws4-capi2-distribution-p-s3-eu-west-1-amazonaws-com.ezproxy.lib.monash.edu.au 


(better view # a seperator: 
s3-euw1-ap-pe-ws4-capi2-distribution-p-s3-eu-west-1-amazonaws-com#ezproxy#lib#monash#edu#au

and the
s3-euw1-ap-pe-ws4-capi2-distribution-p-s3-eu-west-1-amazonaws-com part could be too long as a hostname.

Could it work if EZProxy uses a kind of lookup table for long hostnames?


Example:

Lookup Table: 
s3-euw1-ap-pe-ws4-capi2-distribution-p-s3-eu-west-1-amazonaws-com
<-md5-> d4d8f20b4604668a5b4cc32842eb141d

and  the converted URL would look like this:

d4d8f20b4604668a5b4cc32842eb141d.ezproxy.lib.monash.edu.au

Could this work? Ir there already a feature like this implemented?

Greetings Andreas



> It's not a bug.
> 
> The concept of a 63-character hostname limit is part of:
> 
> RFC1123 2.1 <https://tools.ietf.org/html/rfc1123#page-13>:
> 
>     Host software MUST handle host names of up to 63 characters
>     and SHOULD handle host names of up to 255 characters.
> 
> 
> NOTE: this includes the domain portion of the hostname to go beyond 
> the
> 63 character limit in DNS up to 255 characters.  It provides for up to 
> 4 levels of 63-character names plus the '.' separator to get to 255 
> characters.
> 
> and
> 
> RFC2181 11 <https://tools.ietf.org/html/rfc2181#page-13>:
> 
>     The DNS itself places only one restriction on the particular labels
>     that can be used to identify resource records.  That one restriction
>     relates to the length of the label and the full name.  The length
>     of any one label is limited to between 1 and 63 octets. A full
>     domain name is limited to 255 octets (including the separators).
> 
> 
> Again, the same rationale is used: up to 4 levels of 63-octets plus 
> the '.' separator character for a limit of 255 octets.  One character 
> equal one octet in latin character sets, but one character may equal 
> two octets in multibyte character sets, reducing the effective 
> supported length to 31 multibyte characters per label with a full 
> domain limit of
> 127 characters (including the separators).
> 
> In these instances, the long AWS hostnames combined with the proxy 
> hostname suffix is pushing the length of the individual label beyond 
> what the wire format of DNS permits, which is why the DNS lookups fail.
> 
> Andrew
> 

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