rfc page 4 - Dave's Blog

IPv6 Roundup: Address Syntax on Windows

2008 Jan 9, 11:34

IPv6 address syntax consists of 8 groupings of colon delimited 16-bit hex values making up the 128-bit address. An optional double colon can replace any consecutive sequence of 0 valued hex values. For example the following is a valid IPv6 address: fe80::2c02:db79

Some IPv6 addresses aren't global and in those cases need a scope ID to describe their context. These get a '%' followed by the scope ID. For example the previous example with a scope ID of '8' would be: fe80::2c02:db79%8

IPv6 addresses in URIs may appear in the host section of a URI as long as they're enclosed by square brackets. For example: http://[fe80::2c02:db79]/. The RFC explicitly notes that there isn't a way to add a scope ID to the IPv6 address in a URI. However a draft document describes adding scope IDs to IPv6 addresses in URIs. The draft document uses the IPvFuture production from the URI RFC with a 'v1' to add a new hostname syntax and a '+' instead of a '%' for delimiting the scope id. For example: http://[v1.fe80::2c02:db79+8]/. However, this is still a draft document, not a final standard, and I don't know of any system that works this way.

In Windows XPSP2 the IPv6 stack is available but disabled by default. To enable the IPv6 stack, at a command prompt run 'netsh interface ipv6 install'. In Vista IPv6 is the on by default and cannot be turned off, while the IPv4 stack is optional and may be turned off by a command similar to the previous.

Once you have IPv6 on in your OS you can turn on IPv6 for IIS6 or just use IIS7. The address ::1 refers to the local machine.

In some places in Windows like UNC paths, IPv6 addresses aren't allowed. In those cases you can use a Vista DNS IPv6 hack that lives in the OS name resolution stack that transforms particularly crafted names into IPv6 addresses. Take your IPv6 address, replace the ':'s with '-'s and the '%' with an 's' and then append '.ipv6-literal.net' to the end. For example: fe80--2c02-db79s8.ipv6-literal.net. That name will resolve to the same example I've been using in Vista. This transformation occurs inside the system's local name resolution stack so no DNS servers are involved, although Microsoft does own the ipv6-literal.net domain name.

MSDN describes IPv6 addresses in URIs in Windows and I've described IPv6 addresses in URIs in IE7. File URIs in IE7 don't support IPv6 addresses. If you want to put a scope ID in a URI in IE7 you use a '%25' to delimit the scope ID and due to a bug you must have at least two digits in your scope ID. So, to take the previous example: http://[fe80::2c02:db79%2508]/. Note that its 08 rather than just 8.

roundup ip windows ipv6 technical microsoft boring syntax

Date Time Formats

2007 Sep 27, 2:17Starting on a new simple project I wanted to get the history of my Delicious links. Delicious has an export tool available via the settings section so I thought I'd try that. However, the links aren't exported in XML not even in XHTML but rather in HTML. Shocking. An example:

"Don't Tase Me, Bro!" (UF Student Tasered Remix)

Remix of the 'Don't tase me, bro!' guy getting tasered.At this point I'm already not going to use this file because its in HTML but I'm even more disgusted by those date time values. Raymond Chen of the Old New Thing posted about recognizing timestamps and timestamp sentinel values. From the first blog post and with the use of a calculator for base conversion one can tell that those are UNIX style timestamps counting the number of seconds since 1970.

It reminds me of my hatred for the MIME date time format I developed working on my webpage's server side parsing of atom and RSS. Atom is of course my favorite as Atom uses the Internet date time format described in the following documents. Here's an example of one 2007-09-27T020:50:00.000-08:00

• W3C Recommended Date and Time Format
• IETF: Date and Time on the Internet: Timestamps
• XML Schema dateTime

On the other hand the evil and villainous RSS uses the MIME date time format now described in the more recent IETF MIME standard. Here's an example Thu, 27 Sep 2007 20:50:00 -0800
The Internet date time format has the advantage of being so easy to sort. An alphabetic sort with normal C-style collation rules of strings containing Internet date times will also sort them chronologically. This is not the case for the MIME date time due to the preceding day of the week and the spelled out month name. This also means that when producing these you have to figure out the day of the week and when parsing them you have to match month names rather than just parsing out numbers. Anyway now days if I see mention of a date time in a new proposed standard or spec I be sure to point out the numerous advantages of the Internet date time format.

date xml html feed time technical date-time code atom rss

Commenting Wishlist

2007 May 1, 4:33In the past I've come up with ideas for software and find that the very idea is implemented soon after. So this time rather than getting down about it I'm going to make it work for me. I'll state what I want to use and hope that its magically implemented. In order to uniformly support comments on my website I want a web service with the following features:

• Allow users to view and add comments for any particular URI.
• Use OpenID and optionally Card Space to identify users.
• Use a captcha system that's optionally cute or humorous.
• Has atom or rss feeds of the comments available.
• Doesn't require users to register.
• Doesn't require any extra steps for commenting on a URI that no one has commented on.

I'm going implement this now so no one go off and do it before me so that I can use it without having to do anything...technical homepage

Delicious shortcut tag

2007 Apr 8, 3:05Shortcut Tag?
I just saw this on another user's delicious links: a link to ESV search that's tagged with, among other things, "shortcut:esv". When viewed on del.icio.us there's a text box that lets you search using that link. I hadn't seen this before, but it seems pretty cool and I'm surprised I hadn't seen it previously. A delicious post with such a tag ends up looking like the following: I tried searching for information on this and I've found other delicious users doing the same thing, but nothing about the tag itself. If you know any information especially official information from del.icio.us itself please post links in reply to this post. So without further preface here's what I've learned about the del.icio.us shortcut tag.

How-to
To get a search box in your del.icio.us links make a post that satisfies the following requirements:

1. One of the tags must begin with the text 'shortcut:'. You can have more text following that in the tag if you like but it must at least start with 'shortcut:'.
2. The 'url' you post must be a shortcut url rather than an actual URL. It must contain a '%s' with a lowercase 's'. When you enter text into the textbox on the del.icio.us page the text will replace the '%s' after being percent-encoded. For example 'http://www.google.com/search?hl=en&q=%s' is the shortcut url for Google and if you type 'foo bar' into the textbox the URI you will navigate to would be 'http://www.google.com/search?hl=en&q=foo%20bar'.

Complaints
This is neat but I do have a few complaints:

1. The text from the textbox is percent-encoded before replacing the '%s'. Most sites use application/x-www-form-urlencoded which encodes spaces as '+' rather than '%20'.
2. The shortcut url format seems to be taken from Mozilla's Firefox Custom Keywords. Its a shame it wasn't based on something more adaptable like the OpenSearch URL template syntax.
3. A '%s' in the url means technically what you're submitting to del.icio.us isn't a URI as defined by the standard.
4. Allowing text after 'shortcut:' means you can't look at all of a user's shortcut using this tag.

The next step is to create a tool to sync my IE7 search providers with my shortcuts saved to delicious...technical howto tagging tool tag delicious