C# #define. Missing the easy stuff

The OO crowd sometimes just goes overboard. C# and #defines are an example. C# does provide support for defines, but not for defines with values. So you can write code like:

      #if foo
              Console.WriteLine("foo is defined");
              Console.WriteLine("shoot, its not defined");

But, the designers left out support for #define FOO=VALUE on the grounds that its “macros are a bad idea in general”. See other non-thinkers that spout the same idea here.

The reason these guys think its okay to not have macros is because they’ve never coded in the large. They’ve never built real projects. For any developer that HAS actually written real code, they know that real code invariably requires a set of tools and resources to fully assemble the final product. This includes utility libraries, installers, uninstallers, profilers, memory checking tools, etc, etc. And you always want to have a few key things that you pass between each of these tools. One of the simplest ways to do this is to use the #define NAME=VALUE syntax. Its not graceful, but its so simple that almost every tool out there provides support for it. When you are using someone else’s tool, you just don’t have the luxury to be screwing around with ideals of “macros are bad”.

Ack. Well, if you haven’t guessed it already, today I’m trying to automate my build processes. I have different tools to link together, and the WEAK LINK in the chain is the C# compiler lacking macros.

The solution I’ve settled on so far is use of environment variables. Its not too bad, and mostly usable in other programs as well. Code looks about like this:

   string version = System.Environment.GetEnvironmentVariable("PROG_VERSION");

But this is a lot more cumbersome that using pre-processor macros because its inline code. Now you’ve got to make sure this is initialized and loaded in the right place, etc etc. I’ll keep looking.

Ack. Get off your high-horse and allow macros!!!!!
Read more

Security for self-patching software

For Chrome, I had to create a network update facility. This is a pretty simple task on the surface, but it has some interesting security implications. Specifically, what happens if someday my website gets hacked and someone replaces my “patch” with a virus? Then would all my customers auto-upgrade a virus? That would be awful, so I want to protect against that.

Keep in mind, however, that all these other applications you are running on your desktop probably have no security against this. They happily connect up to some server somewhere and download a program. If the right evil-doer gets into that website, who knows what your system might download.

So, how to protect against this? Well, the obvious solution is to sign your code. Signing your code generally uses asymmetric encryption (encryption methods that use a public and private key pair like RSA or ECC).

Microsoft has a technology called Authenticode which they use in Internet Explorer to help you avoid downloading bad programs. (Most users probably read “this code is not authenticated” but click right through to install anyway) But for my purposes, I want to verify a signature within my own code- authenticode doesn’t let me do that easily. And, even if it did, I’d have to go get a certificate from Verisign or Thawte – and that would cost me $150 or more.

So, I came up with the following solution. Thanks to help from CodeProject for a couple of sample source code projects.

The idea is that when my software wants to do an upgrade, it downloads a small XML file from the server which tells the application what new version is available, where to download it from, etc. The XML file also contains a signature section, which was created by signing the entire XML file with my private key.

So, I create a private key/public key pair using Microsoft .NET’s SN.EXE program, and I store that away in a safe place. I extract the public key, and hard code that into my program file which I ship to customers.

When the program checks for updates, it downloads the XML file. It can now verify the authenticity of the XML file by checking that it was signed with my key. Inside the signed portion of the XML is a MD5 hash. The MD5 hash is a hash code for the to-be-downloaded patch. Assuming that the signature of the XML file matched, we will save away this MD5 to compare against the MD5 of the file we actually download.

Now the application proceeds to the downloading step. After that completes, it verifies the MD5. Since the XML file signature matched, I know that this MD5 hash is “approved” by me. And since the MD5 of what I actually downloaded matches the signed XML file, I know I can safely install the file.

Amazingly, in C#.NET, the code for the entire signing/verification process is an executable that is less than 40KB.

The great thing about this approach is that its quite safe and hard to break. I didn’t have to go get a certificate and shell out bucks to anyone.

One risk would be if my public/private key pair was ever stolen or comprimised. If so, I’d have no way to update existing clients. But this is a problem that mostly exists in the real world today. CRLs (Certificate Revocation Lists) can be used when you have a real certificate to find out if a public key that you once used is still valid. But most software doesn’t implement CRL checking anyway 🙂 I suppose that will change someday.

And I think this is better than Microsoft’s authenticode. Authenticode will still allow the poor user (who didn’t know why he got some funky security warning) to install the code. My approach flat-out-rejects anything which doesn’t pass my signed-code test.

Well, thats my solution. Hopefully I didn’t forget anything silly. And I hope that my software is a lot more secure against downloading bad patches than most of the software out there.

Chrome, Installers, and NSIS

Good news on Chrome this week. We released our 0.7 versions of the product, and they seem to be doing really well in the field. Many of the wierd stability problems are gone. There have been a few minor bugs to fix. We’re so lucky to have users that are patient and helpful. They’ve been just wonderful at helping us get the product to work.

OK – about installers. So far, we’ve used the Microsoft Installer to build our packages. Its been pretty nice. The way the Microsoft Installer works is that most of the program is resident in Windows already. Windows XP, for instance, ships with a version of the Microsoft Installer Service 2.0 built in. Whenever you launch a MSI file, its really the built-in installer service which is doing the work. The contents of the MSI file is basically a big database. Microsoft internally calls the database “Orca”. The Microsoft Installer software knows how to read this database and act appropriately. I have found that there is a tool (its in the developer’s SDK) for Orca which is worth downloading if you spend much time with an MSI.

For simple installs, MSI’s are great. but I’ve found they have a number of drawbacks for us:
1. Installation is slow. Our 2MB application takes about 30 seconds to install. Why?
2. Upgrading existing software is tricky. You have to get a whole bunch of options right in visual studio for this to work. I ran into one bug which is that because my product is versioned “0.70.0”, upgrades just don’t work. Turns out (if you install the Orca database tool) that there is a rule which gets auto-generated to upgrade my version from a minimum version of to a maximum of 0.70.0. Well, of course that won’t work – my version is below 1! I think its just a bug, but I wrestled with that forever.
3. Some customers are reporting this really wierd error which says the MSI file is corrupt. Its intermittent, and only some users see it. But its happening at a rate thats high enough that I don’t believe its corrupt downloads. Searching the net for these errors, you’ll find zillions of other people with the same problem.

Solution: Use a different installer. I found NSIS (from NullSoft, the makers of WinAmp), which I like. You definitely don’t get any of the gravy that comes along with a Visual Studio-like environment. Scripting NSIS is back to unix-land. I saw there are some visual script editors for NSIS available, but I didn’t try them. It took me a good couple of days to really cleanup the installer, but in the end it was worth it for reasons I hadn’t originally anticipated:
– The size of my download decreased from 1.25MB to 0.65MB. I don’t know what MSI’s are doing, but they are just too big. Its the same files in each, but NSIS is able to make downloads HALF the size.
– Install is amazingly quick.
– Uninstall is amazingly quick.
– You get full control over what happens on install, uninstall, upgrade, etc. There is no “behind the scenes” magic. Of course, this is a blessing and a curse.
– You get to customize the graphics in a much nicer way.

So, I recommend NSIS to anyone looking for a nice installer.

There are some features which you loose when moving away from MSIs. For instance, MSIs come in with built-in administrative controls which allow IT folks to determine which applications the end user can install. I’m not sure how that all works, but I suspect the MSI is spending a lot of time figuring that out.

Go OpenOffice

This is really wordy. But its got a great point at the bottom. If you can’t get through this wordy doc, then just click right now over to Open Office and check it out. Otherwise, read on about how I found it… This is a real life story of why software piracy is good for Microsoft, and how Microsoft is making a big mistake right now.

I bought a new PC this week. Its nice. I decided to do some video editing, so I got 2.8GHz, 800MHz FSB, 512MB system with an ATI 9000 All-In-Wonder graphics card. Thats a pretty decent card for the video input. I ended up buying the thing in parts, because it was substantially cheaper than the assembled systems. Normally, assembled systems are cheaper these days, but with my fussiness over the DVD writer and the ATI graphics card, I couldn’t find one with the stuff I wanted.

Anyway, it turns out that installing the hardware was the easy part. The hard part was getting Microsoft Windows to work. I wanted to upgrade to Windows XP, and then I stumbled across the no-piracy stuff thats in there. With XP, it turns out that Microsoft requires activation over the network. They know if your key has been used before, and they won’t let you activate if it has. Of course, I was up late at night trying to get the thing installed, so I was using a CD that I got with my laptop (a legal copy, just not for my new machine!). Well, Microsoft was successful in preventing me from getting my installation done. They will let you try the OS for 30 days before they’ll lock you out, but curious me actually set the clock forward 3 months to see what happened when the 30 days was up. Yup – they locked me out !!!

So I got on the phone to MSFT calling the number that was given to me in the activation application from Microsoft. I told them I wanted to buy two copies of WinXP Pro. The nasty woman on the other end of the phone was clearly angry with me. She kept going on about how my license didn’t allow me to install the software. I told her I knew that and I wanted to give her my credit card number so I could pay for two copies. Needless to say, that was beyond her competence.

So, the next day, I took a trek to Fry’s and bought an OEM copy of windows. The OEM version costs $99, while the regular version costs $150. But, you have to buy hardware in order to qualify for the OEM version. And my system, purchased the day before, didn’t qualify. The nice customer service person directed my to their screw isle (no pun intended), where I picked up a $0.99 bag of computer case screws to qualify as my hardware purchase to go with my OEM version of XP.

Where does this leave Microsoft? Did they win? Did they lose? Well, in the short term, they clearly won. I purchased two copies of Windows XP that I probably wouldn’t have otherwise purchased. In the long term, however, they lost. I’m definitely not going to be upgrading to any new versions in the future unless I absolutely have to. And, I’m going to start looking for alternatives to Microsoft more seriously now too. From what I’ve read, they’ve locked down Microsoft Office tightly with keys just like they did for Microsoft Windows. So, this means I’m looking for alternatives to both.

I’ve never been a linux or open source bigot like many software developers are. I like linux, of course (the server which is serving this page is running Linux), but I don’t want linux on my desktop. So for now I still need Windows as my operating system. And I will admit it – I like windows! Microsoft has really done a great job with XP, and I have no major complaints about it. In the long run, buying it, even for home, is may be okay. But I’m going to look a lot more at competition if I *have* to pay for it rather than *elect to pay for it.

So, I think this anti-piracy crusade could be long term trouble for Microsoft. If they had just let me have it for free at home, I’d use it at work (and pay for it). Why would I look for anything else? I think the software is good – I learned it at home (for free) and I want it in the office too, because that makes my job easy.

But, instead of having me use Office at home, I’m now out looking for something else thats cheaper. And the only reason is because Microsoft wanted to get $99 from me. (Actually office costs more – $200) I’m really liking the alternative I found so far. Yes, I’ve still got XP, of course, but Microsoft Office is NOT on my systems anymore.

I found OpenOffice – an open source based alternative to Microsoft Office. Bundled in the package is a Excel, Word, and Powerpoint – oh – they call them “Spreadsheet”, “Document”, and “Presentation”. So far, its awesome. The install was incredibly smooth and the visual presentation was great (although it did give me some too-techie gripe about not having Java installed?). And now its worked with every word doc and spreadsheet I have. Literally- I see no bugs, and I’m absolutely blown away. This is really good software.

So, Microsoft, we’ll see who has the last laugh. I’m a small business owner, and I obviously hope my business grows. In the future, I’ll need to purchase Office-like software for my own employees. Had you not added this anti-piracy thing to my Windows XP install, I’d absolutely be purchasing Microsoft Office. Why would I look for anything else? I know how to use it, I like it, and its cheaper to not have to train employees to use something else. Now, however, I’ve discovered OpenOffice, and I’m going to use it for a while. Other home users are doing the same thing. And the next time I need to purchase a Word Processor, you may not get my business. While I may not have been paying when I was at home before, at least you were getting my mindshare. Now, I’m still not paying, and I’m not even running your products.
Read more