Category Archives: Technology

Really everything related to technology

Network, Web

HTTP cookies IETF working group

So finally (remember I mentioned this list when it was created back in January 2009) an IETF http-state working group was created, with the following description:

The HTTP State Management Mechanism (Cookies) was original created by Netscape Communications in their Netscape cookie specification, from which a formal specification followed (RFC 2109, RFC 2965). Due to years of implementation and extension, several ambiguities have become evident, impairing interoperability and the ability to easily implement and use HTTP State Management Mechanism.

I’m on the list from the start and I hope to be able to contribute some of my cookie experiences and knowledge to aid the document to actually end up with something useful. The ambition, while it was “toned down” somewhat since the initial posts of the mailing lists, is still fairly high I would claim:

The working group will refine RFC2965 to:

  • Incorporate errata and updates
  • Clarify conformance requirements
  • Remove known ambiguities where they affect interoperability
  • Clarify existing methods of extensibility
  • Remove or deprecate those features that are not widely implemented and also unduly affect interoperability
  • Add features that are already widely implemented or have a critical mass of support
  • Where necessary, add implementation advice
  • Document the security properties of HTTP State Management Mechanism and its associated mechanisms for common applications

In doing so, it should consider:

  • Implementer experience
  • Demonstrated use of HTTP State Management Mechanism
  • Impact on existing implementations and deployments
  • Ability to achieve broad implementation.
  • Ability to address broader use cases than may be contemplated by the original authors.

The Working Group’s specification deliverables are:

  • A document that is suitable to supersede RFC 2965
  • A document cataloging the security properties of HTTP State Management Mechanism

I think this is a scope that is manageable enough to actually have a chance to succeed and its planning is quite similar to that of the IETF httpbis group. Still, RFC2965 lists a huge pile of stuff that has never been implemented by anyone and even though it was a while since I did read that spec I also expect it to lack several things existing cookie parsers and senders already use. The notorious IE httpOnly is an example I can think of right now.

Development, Open Source, Technology, Web

My HTC Magic Review

This is my first “smartphone” I’ve owned myself so of course I have nothing else this fancy to actually compare against. I’ve played around with others’ a few times but that doesn’t really count. I’ve owned perhaps 8 mobile phones since I got my first one 1996, and they have all been Nokias and Sony Ericssons.

I was never really interested in iPhone due to many reasons. It is not open. It has a (very) restricted app distribution mechanism. It forbids apps from running simultaneously etc. And it has a pretty strong connection with itunes with no proper mass-storage syncing supported. But I admit that it has a slick UI and many cool apps.

My plan is to get some Android hacking going eventually and this is basically the first Android phone that has reached Swedish soil. I mean without requiring me to bend over backwards to get it, as I’m sure I could’ve bought previous Android phones from obroad if I really wanted to.

Random good things:

  • it’s fast, most things run faster than on my previous Sony Ericsson thing and yet this is way more advanced with much bigger screen estate and fancier UI
  • it has a nice gui that you mostly can guess how to work with
  • I love being able to use a qwerty-style keyboard when messaging instead of relying on T9 etc
  • wifi is fun, but with a decent data plan it basically only brings me slightly improved speed and I often can’t even tell the difference!
  • the integration with the Google services are nice, gmail and maps most noticeably
  • there really are a bunch of existing cool apps (I know iphone has lots more, but there are still thousands)
  • it has a much better approach to messaging, similar to what I’ve seen in the iphone, than I’ve ever experienced in a Nokia or Sony Ericsson. It focuses on conversations and keeps the “thread”.HTC Magic
  • I really really like the feeling of it being a networked thing that also can make phone calls. I can browse, use maps, use gmail just as easily as I can message or call people. With my previous phones all the internet-related services always felt tacked on like a very late afterthought.
  • The notification system is nice, and the three-screen wide “home” with its widget-system is really neat.

Bad stuff:

  • I’ve had some apps crash on me on occasion. But it’s rarely a problem as they’re restarted automatically for me.
  • Toggling wifi on/off a lot can sometimes lead to me not getting any data network at all, and I’ve had to reboot the phone to get back to phone-based (Edge/3G) data.

On-screen keyboard

Of course any and all geek friend I have ask me about how I deal with the on-screen keyboard. I must admit I’m still quite fond of it. Mostly because a physical keyboard makes the phone clonky and it adds physical contraints and wear-points that I don’t like. So the keyboard is a bit small, especially when the phone is in portrait mode, but the suggested completions are fine and I believe I’m already typing pretty quickly on the thing. When I ssh’ed from the phone to one of my servers I did find the obvious lack of cursor keys (to for example navigate an ordinary ncurses-based app or the command line history of a bash prompt) but other than that I really can’t complain.

Background Applications

One obvious advantage compared to iphones is of course the ability to run applications exactly the way I’d like. I can actually run the irc client and then have it in the background while I go browse the web or answer a call or whatever and then at my choice go back to the still connected irc client. In fact when playing with this it feels like a really ridiculous restriction of the iphone.

Comparing to my SE w550i

My previous phone is 94 grams compared to the Magic’s 116. The magic has a much bigger screen. The magic is roughly 11mm wider and 14mm taller. That makes it use 30% more volume (85 cm2) but still fits fine in the front pocket of any set of pants I use. The magic claims a lot longer battery life, but given that it has so much functionality I can’t help to play with all the time I doubt it’ll notice. It’ll more likely run down fast simply because I’ll use it more.

I’m also pleased that there’s no problem to just plug in the Magic to my Linux desktop and copy/sync the photos and the videos etc.

Google Integration

I realize some people will feel that the very tight integration with Google and Google’s services is a downside as it adds just another item that Google “owns” in your life. Still, it makes the experience very slick and as a user I get a lot of stuff “for free” as it just connects to lots of things that I already used and had accounts on. So gmail, sharing photos on picasaweb etc “just works”.

Development, Linux, Rockbox, Technology

Decrypting ipods

Recently we’ve seen progress by the linux4nano guys in their quest to get custom code to run on an Ipod Nano 2nd generation. They’ve apparently managed to extract the bootrom off a 2nd gen ipod nano (my copy of their extracted data is here – a reminder on objdump usage: “arm-elf-objdump -D --target binary -marm [file]“). I believe their intent is to port Linux to the newer ipods. Possibly ipodlinux. They do mention providing the necessary info to Rockbox and yes we will welcome it.

A large crowd of Rockbox hackers have joined their IRC channel and have been hanging out with them and helped out discussing ideas and pushed them towards publishing their news and infos on how this all is accomplished etc. Their SVN repo hosts some (most?) of the tools made so far.

The Rockbox wiki page for nano2g has been updated and hopefully it will keep track of what happens.

There have been speculations, but I don’t yet know based on what facts, that this recent news and hacks will be usable on other recent (encrypted) ipod models.

Summary: very interesting progress has been made. Lots of it is still left to figure out. There seems to be a bunch of skilled people around and now we’re seeing information and documentation for this getting published so I can’t but to hope for a bright future!

Development, Electronics, Rockbox, Web, Windows

Concepts of a new distributed build

It was time to make an overhaul of our distributed builds system for Rockbox. The one currently in place is quite fancy and it does build 106 builds in around 7-8 minutes, but during the years it has served us we have found a few areas where we want to improve.

The goals for the new system were primarily:

  • do all the builds faster
  • reverse the connection so that people can contribute clients easier
  • make a system that is more allowing for slower machines to contribute

The biggest weaknesses of the existing system:

  • The master uses ssh to the distributed clients, which forces them to have an accessible ssh server and port etc. It also makes it awkward for people behind NATs who wants to run more clients.
  • It only hands out a particular build to one client, so thus if a large build happens to get handed to a slow client towards the end of a build round, all the other clients will sit idle waiting for the last client to finish.
  • The build and the subsequent upload of results to the master are synchronous, so thus a client with a very slow uplink may spend a significant time on the upload before it can start the next build.

The  new system is currently in development. It consists of a server that runs on one of our main servers, and there’s a client script that each volunteer contributor runs on their systems.

The clients connect to the master on a dedicated TCP port, specifying user name, password, name of the particular client instance, what particular architectures the client can build and how many bogomips the client boasts. While bogomips is a bogus way to measure anything, we’ve started out using it for a rough way to sort the the build clients based on speed.

The clients keep connected to the server all the time. There’s a ping message from the master every N second of idleness to make sure the connection is kept alive. As soon as the master wants the client to do a build, it sends a message to it detailing exactly how it should build it and using what SVN revision. The client will then do the build at once, upload the results using HTTP to a dedicated place and then tell the server the build is complete.

The server knows about all builds to do at a  commit, what we call a build round. It has a rough “score” or “weight” for each build that grades them in a slow to fast order. When a build round starts, the server will first sort all builds based on number of times they’ve been handed out and as secondary sort key the “weight” of it. Then it loops over the currently connected build clients and hand out builds from the sorted build table. The server then continues to do that until all clients have three builds each to build. As soon as a build is reported to have been completed by a client, that client will get the next build from the sorted build list.

If a client connects to the server and the server deems the client to be too old (since it does specify its version in the handshake message), it will be told to update to a specific version instead and come back then. This way the server can update all build clients when important things are fixed.

The clients will soon start to get assigned builds that already have been assigned to another client. This is not a problem but in fact our intention. The client that completes the build first will simply tell the server, and the server will then tell all the other clients that build that same build that they should cancel that particular build.

A client that joins the server in the middle of a build round will simply get a bunch of builds immediately and join in. A client that disconnects during a build round simply won’t complete its builds and other clients will instead do them. The system is also tolerant against the fact that bogomips is lame to compare computers with, and that the build “score” may not be very accurate or even that some server will have very slow or very fast upload speeds at unpredictable times.

The build master itself does not know when to start a new build round. It simply knows about the concept and it knows how to tell clients to complete a round. To make the master to start a new round, you need to connect to the server’s listening port and issue a special command and provide a password and then you can tell the server to start a build of a specific SVN revision. Or to queue up a build to be performed after the current one if there happens to be one in progress already.

When a full build round is complete, a hundred or so builds have been done, and full packages and log files are now in a directory on the build server, the server will simply trigger an external script that then takes care of updating our build table etc. In fact, every single completed build will optionally trigger an external script to allow web pages or stats pages to get updated as we go.

This build system is currently pretty Rockbox-specific as this is the project and development system we’re writing this for, but there’s really nothing in this that must be this way. I’m sure that if someone (you?) wants to adapt this for another project, I’d be more than happy to assist and to help ensuring that this becomes a more generic distributed build system. Just raise your hand and step forward!

At the time of this writing, (primarily) me and Björn are still ironing out quirks in this new system to hopefully get it going live real soon…

Rockbox

Network, Web

encrypted file transfer protocols compared

I like putting up some explanatory “this versus that” documents on stuff I know a little about. I’ve done things like curl vs wget, ftp vs http and http vs bittorrent in the past.

This time, I decided it was about time to do a technical comparison of the four major encrypted file transfer protocols SCP, SFTP, FTPS and HTTPS and explain how they differ in as many aspects and viewpoints as possible. I quite often get questions about how some of these compare against some of the others and why you’d use one instead of another etc. I hope this document will help people to find such answers themselves.

Of course I do mistakes and sometimes express myself in muddy ways, so your feedback and help is important. You can help me make this comparison become better!

http://daniel.haxx.se/docs/encrypted-transfer-protocols-compared.html

It’s still rough and all, but what question and comparisons between them do you miss? What mistakes have I done? What parts aren’t spelled out clear enough?

Network, Technology

HTTPbis at IETF75

Mark, one of the editors of the ongoing HTTPbis efforts, first mentioned that there wasn’t going to be any HTTPbis meeting on the upcoming IETF75 meeting in Stockholm July 26-31, 2009. I felt a bit sorry for that since I live in Stockholm, I’m a bit involved in the HTTPbis work and I’ve never been to a IETF meeting.

It simply must have been due to my almighty powers, but apparently two of the editors are going here anyway and there has now been a request for a HTTPbis session during the meeting.

I’m looking forward to this! Hopefully it’ll bring some fun talks on tech we care about, but also meeting cool people in real life that I never met before.

Stockholm

Oh, and am I the only one who can’t find the dates anywhere on ietf75.se?

Electronics, Linux

Kernels on those phones

1 Comment

So Google says there could be 18 phones running Android by the end of this year. In Sweden we just days ago got HTC Magic, the first ever Android phone showing up here (tied to a ridiculous operator deal that makes me and lots of my friends not go that route). Then Palm shipped their Palm Pre just days ago, also based on Linux.

This has brought the interesting questions: how is the state of these kernel HTC Magicports in regards to the mainline Linux tree? They’re both using ARM cores (of course).

The ARM kernel maintainer Russell King himself is not impressed. Apparently Google hasn’t even tried to push their work upstream to the kernel in a long while. The tone in that discussion did make it sound as if they might be starting to work on this again now.

The Palm guys apparently haven’t even yet shown any code at all, but is said to be releasing their code within two weeks to opensource.palm.com.  They have not even tried to push their work upstream, so I figure they’re either not even going to bother or they are facing a rather steep uphill battle in the future.

Electronics, Rockbox

Lyre

I’ve previously blogged about the initiative to build an own open hardware platform that can run Rockbox fine, and just today I noticed their new site is up and alive at:

http://lyre.sourceforge.net/

The hardware has changed quite significantly since the last blog entry of mine, and they’re now using a LPC3130 from NXP instead of the Atmel they had before, and I believe they’ve also changed codec/DAC etc. Me knowingly, Rockbox does not yet run on this newly produced board.

Lyre PCB

I should probably also add that this board is of course still quite far from being portable and there’s no news or info anywhere on how or if you can actually get one of these yourself yet.

Electronics, Linux

Eeepc with Linux and Swedish 3g

This is a follow-up on my “getting the new toy” from a week or so ago. An Eee PC S101.

I didn’t like easypeasy on it. It seems that distro is more or less Ubuntu Netbook Remix (UNR) with a little EEE flavor applied. What’s not to like about it? They seem to think that because this is a netbook, normal UI guidelines no longer apply so therefore they’ve scrapped the ordinary main desktop (and its menu) concept and instead have a new full-screen “app launcher”. That’s not too shabby, but it comes with another idea that I can’t accept: they run all applications in full-screen mode by default.md400 And I couldn’t figure out how to alter that default.

Full-screen might be fine for some apps at some times, but then I’d like to explicitly ask for it instead of having to learn now to “unmaximize” each app (they’ve also removed/altered the window decorations so there are no standard three buttons on the upper right corner of the maximized windows). To top it off, it seemed that the latest easypeasy isn’t built with the latest ubuntu and thus it failed to connect with my 3g modem…

Instead I took the base version of eeebuntu for a spin and that is so much closer to what I want in a linux. It’s ‘base’ so it only comes with the bare minimum. It has no fancy alternative UI but relies on the traditional well-proven and by me liked X11 (gnome) desktop.

I inserted my Sony Ericsson MD400 USB 3g modem that I got from Telenor/Bredbandsbolaget and within a few seconds I was online. It couldn’t have been a much smoother ride.

I know people have expressed opinions that it’s a better idea to use laptops/netbooks with an internal 3g modem so that you don’t have to use any external devices so that it’ll be more slick and all. I think I was of that opinion as well until I got this usb thing in my hand. It’s basically just a tad larger than any ordinary USB memory stick (70 x 28 x 15 mm) so it’s really not much “in the way” or disturbing when inserted in a laptop and it comes with windows drivers on it (as it dual-serves as a usb mass-storage device as well). It makes it a perfect little device to move between different laptops. We have so far three laptops in our household and now I can get any of them onto 3g if I want to.

A little side-note on my eeebuntu install on the SD card: when I ran unetbootin I selected to install the “live/install” version on the hard drive (which of course is a SSD but anyway) to then install it on my SDHC card, but it simply wouldn’t work. I tried three times and every time it froze somewhere in the middle of the install. When I then re-ran unetbootin and made a boot usb stick, and then ran from there instead when I did the install, it worked perfectly…

Electronics, Technology

More HD sound

2 Comments

Proving my point from before that everything wants to be “HD” these days, I read the Zune HD specs that come out recently and in that I found out that it claims to support HD radio. Amusingly enough, it does not claim mp3hd support which probably would’ve made the buzzword bingo crowds go wild. We can always hope for the next model! 🙂

So what is HD radio? The site says:

Instead of sending out one analog signal, stations send out a bundled signal – both analog and digital. Because it is digital, textual data such as traffic, stock info and song titles can be sent out, as well.

From what I understand, pretty much the same way RDS is already done.

The technology is not even new. The site lists news items from 2006 and yet I’ve never heard of it before. They claim FM stations get “CD-quality sound” and (as I find pretty funny) AM stations get “FM-quality sound”. What is “CD-quality” in this context I wonder? I find no mention or details on what exact codecs or bitrates etc they use. Wikipedia’s page to the rescue: it says you get approximately 100-150 kbps of a lossy “proprietary iBiquity HDC codec” which claims to be able to provide “CD quality as low as 64 kbit/s”. Somehow I think that sounds a little too good to be true. According to wikipedia HD radio beats DAB in audio quality.

And to top it all of, the FAQ describes what the HD means:

It does not mean either hybrid digital or high definition, it is simply the branding language for this new technology.

Personally I’ll just rather go IP all the way and stream my music/radio/video over that. I think media or content-specific transfer mediums/concepts of this kind are technologies of the past. For this reason, I don’t think DAB+ will have much of a future either.