windows page 6 - Dave's Blog

Leaving the IE Team for Windows

2010 Feb 26, 8:40

I'm making a switch from the IE team to the Windows team where I'll be working on the next version of Windows. As a going away surprise Jen and Nick added me to my gallery of Bill Gates (discussed previously). Here's a close up of the photoshopped cover.

Before:

After:

microsoft bill gates photoshop windows

Methods of Watching TV

2010 Feb 3, 1:09If you've got cable, Internet, and Netflix you end up with a large number of TV viewing options. Its nice to have the options but is there some way to collect and summarize my available options at any one time?

	TV	PC
Comcast TV	Xbox 360 + Windows Media Center	Windows Media Center
Comcast OnDemand	Cable box	Fancast
Hulu	Xbox 360 + PlayOn + Windows Media Center	Hulu
Netflix Watch Instantly	Xbox 360 + Netflix App	Netflix Watch Instantly
Netflix DVDs	Xbox 360	PC

tv xbox 360 wmc dvr

WPAD Server Fiddler Extension

2010 Jan 5, 7:42

I've made a WPAD server Fiddler extension and in a fit of creativity I've named it: WPAD Server Fiddler Extension.

Of course you know about Fiddler, Eric's awesome HTTP debugger tool, the HTTP proxy that lets you inspect, visualize and modify the HTTP traffic that flows through it. And on the subject you've probably definitely heard of WPAD, the Web Proxy Auto Discovery protocol that allows web browsers like IE to use DHCP or DNS to automatically discover HTTP proxies on their network. While working on a particularly nasty WPAD bug towards the end of IE8 I really wished I had a way to see the WPAD requests and responses and modify PAC responses in Fiddler. Well the wishes of me of the past are now fulfilled by present day me as this Fiddler extension will respond to WPAD DHCP requests telling those clients (by default) that Fiddler is their proxy.

When I started working on this project I didn't really understand how DHCP worked especially with respect to WPAD. I won't bore you with my misconceptions: it works by having your one DHCP server on your network respond to regular DHCP requests as well as WPAD DHCP requests. And Windows I've found runs a DHCP client service (you can start/stop it via Start|Run|'services.msc', scroll to DHCP Client or via the command line with "net start/stop 'DHCP Client'") that caches DHCP server responses making it just slightly more difficult to test and debug my extension. If a Windows app uses the DHCP client APIs to ask for the WPAD option, this service will send out a DHCP request and take the first DHCP server response it gets. That means that if you're on a network with a DHCP server, my extension will be racing to respond to the client. If the DHCP server wins then the client ignores the WPAD response from my extension.

Various documents and tools I found useful while working on this:

• WPAD IETF draft document the never out of draft document describing WPAD
• DHCP RFC
• DHCP options RFC
• DHCP Wikipedia article which includes helpful byte layout tables for DHCP messages.
• Fiddler Wiki esp. the dev section but also the portion on the new preferences API.
• Fiddler Dev Docs and for those things not covered in the Fiddler docs, Visual Studio's name completion (or the .NET Reflector) usually served me well.
• Netmon a great network sniffing tool for all my non-HTTP network inspection needs.
• Tiny DHCP Server on CodeProject which implements a conventional DHCP server.

proxy fiddler http technical debug wpad pac tool dhcp

Comcast Digital Switch Impact on My Windows Media Center

2009 Sep 25, 2:19

Irritatingly out of line with what their commercials say, in my area Comcast, under the covers of the national broadcast digital switch, is sneaking in their own switch to digital, moving channels above 30 to their own digital format. Previously, I had Windows 7 Media Center running on a PC with a Hauppauge PVR500 which can decode two television signals at once setup to record shows I like. The XBox 360 works great as a Media Center client letting me easily watch the recorded shows over my home network on my normal TV.

Unfortunately with Comcast's change, now one needs a cable box or a Comcast digital to analog converter in order to view their signal, but Comcast is offering up to two free converters for those who'd like them. The second of my two free converters I hooked up to the Media Center PC and I got the IR Blaster that came with my Hauppauge out of the garage. I plugged in the USB IR Blaster to my PC, connected one of the IR transmitters to the 1st port on the IR Blaster, and sat the IR transmitter next to the converter's IR receiver. I went through the Media Center TV setup again and happily it was able to figure out how to correctly change the channel on the converter. So I can record now, however:

1. I can only record one thing at a time now
2. Changing the channel is slow taking many seconds (no flipping through channels for me)
3. The Hauppauge card can't know if the channel change worked. So if it tries to change to HBO (I get it for free with one of the Comcast packages) which is encrypted and the converted won't show, the channel doesn't change but the PC doesn't know it and ends up recording some other channel.

To fix (3) I need to manually go through and remove channels I don't have from the Media Center. To fix (1) I may be able to get a second IR transmitter, a third digital converter, hook it up to one of the other inputs on my Hauppauge, and go back through the Media Center TV setup. There's no fix for (2) but that's not so bad. All in all, its just generally frustrating that they're breaking my setup with no obvious benefit.digital tv hauppauge mce cable windows media center comcast

Time/Date Conversion Tool

2009 Aug 28, 3:39

I built timestamp.exe, a Windows command line tool to convert between computer and human readable date/time formats mostly for working on the first run wizard for IE8. We commonly write out our dates in binary form to the registry and in order to test and debug my work it became useful to be able to determine to what date the binary value of a FILETIME or SYSTEMTIME corresponded or to produce my own binary value of a FILETIME and insert it into the registry.

For instance, to convert to a binary value:

[PS C:\] timestamp -inString 2009/08/28:10:18 -outHexValue -convert filetime
2009/08/28:10:18 as FILETIME: 00 7c c8 d1 c8 27 ca 01

Converting in the other direction, if you don't know what format the bytes are in, just feed them in and timestamp will try all conversions and list only the valid ones:

[PS C:\] timestamp -inHexValue  "40 52 1c 3b"
40 52 1c 3b as FILETIME: 1601-01-01:00:01:39.171
40 52 1c 3b as Unix Time: 2001-06-05:03:30:08.000
40 52 1c 3b as DOS Time: 2009-08-28:10:18:00.000

(it also supports OLE Dates, and SYSTEMTIME which aren't listed there because the hex value isn't valid for those types). Or use the guess option to get timestamp's best guess:

[PS C:\] timestamp -inHexValue  "40 52 1c 3b" -convert guess
40 52 1c 3b as DOS Time: 2009-08-28:10:18:00.000

When I first wrote this I had a bug in my function that parses the date-time value string in which I could parse 2009-07-02:10:18 just fine, but I wouldn't be able to parse 2009-09-02:10:18 correctly. This was my code:

success = swscanf_s(timeString, L"%hi%*[\\/- ,]%hi%*[\\/- ,]%hi%*[\\/- ,Tt:.]%hi%*[:.]%hi%*[:.]%hi%*[:.]%hi", 
&systemTime->wYear,
&systemTime->wMonth,
&systemTime->wDay,
&systemTime->wHour,
&systemTime->wMinute,
&systemTime->wSecond,
&systemTime->wMilliseconds) > 1;

See the problem?

To convert between these various forms yourself read The Old New Thing date conversion article or Josh Poley's date time article. I previously wrote about date formats I like and dislike.

date date-time technical time windows tool