Re: Java sux! - C# Discussion Boards

Re: INCLUDE Configuration

28-Dec-03 7:17

You're not supposed to compile the whole thing to a typelib, only forward-define the interfaces in your own IDL file and then compile that to a typelib. See the midl.exe documentation for more command-line options. Each IDL file doesn't have a typelib because many are typically meant to be included in other IDL files while being defined in a library elsewhere - this isn't your concern. Do what the linked article I gave you mentions and generate a typelib including the interfaces, structs, and enums you need ONLY. Anymore - unless you're planning on interop'ing the whole COM for a huge-ars library - is just overkill and bloat.

-----BEGIN GEEK CODE BLOCK-----
Version: 3.21
GCS/G/MU d- s: a- C++++ UL@ P++(+++) L+(--) E--- W+++ N++ o+ K? w++++ O- M(+) V? PS-- PE Y++ PGP++ t++@ 5 X+++ R+@ tv+ b(-)>b++ DI++++ D+ G e++>+++ h---* r+++ y+++
-----END GEEK CODE BLOCK-----

Tristan Rhodes28-Dec-03 8:48

Tristan Rhodes

28-Dec-03 8:48

Ok Heath, I think I am almost there.

One last question.

I've looked through the idl files, and a lot of the structures and enumerations I need are embedded in interfaces.

Some of them are in ones that I do not need.

Can I pull them out and put them in the file on their own? Or do they need to be included in the interfaces?

I ask this because STGMEDIUM is represented in objidl.idl by uSTGMEDIUM. Are these the same? As their layout is identical.

Cheers

Cata

Re: INCLUDE Configuration

Nick Parker28-Dec-03 7:13

28-Dec-03 7:13

This thread is starting to have an interesting curve to it.... Poke tongue | ;-P

Just felt like mumbling a little, I have been flipping though one of those Java books Ryan gave me. So far I am unimpressed with the language. Sigh | :sigh:

- Nick Parker
My Blog

Java sux!

Tristan Rhodes28-Dec-03 8:06

Tristan Rhodes

28-Dec-03 8:06

I hated it... it doesn't compile to an executable and runs slow as a 36 stone 1 legged man with a ball and chain round his ankle.

It's also ugly, a real mission to program, and the documentation is nigh on impossible to navigate quickly.

I moved from java in text pad to C# in VS.NET. It was like replacing a wooden go kart with a ferri.

So yeah, burn your java book in the name of all that is holy!

(Well, ok, java might have SOME uses... but... there you go. My experience was bad Frown | :(

)

Can we make an arc? WHEEE!

:p

Cata

Nick Parker28-Dec-03 8:29

28-Dec-03 8:29

It appears that the library itself is lacking, but I haven't gotten into that much yet.

- Nick Parker
My Blog

Tristan Rhodes28-Dec-03 8:34

Tristan Rhodes

28-Dec-03 8:34

My dad would say

"In my days, the only class libraries we had were those built by ourselves."

But my dads about 2000 years old and made computers with sticks and stones.

Wink | ;)

Cata

Heath Stewart28-Dec-03 8:55

28-Dec-03 8:55

Nick Parker wrote:
...but I haven't gotten into that much yet.

I'd say! The Java class library has all the basic stuff, while Swing (added with Java 1.1 I believe) offers a stunning GUI class library over the prevoius AWT packages. And just like .NET, there are a ton of libraries out there (both by Sun and by third parties) to extend the basic functionality below your application, things for encryption, web services, RMI (like .NET Remoting), remoting bridges, and much more.

This doesn't mean I like it, but it serves a purpose and deserves a little respect, especially since it was the first real framework before .NET. Smile | :)

Nick Parker28-Dec-03 9:25

28-Dec-03 9:25

Heath Stewart wrote:
I'd say!

I'd spent about 10 minutes looking at the book when I made that comment, obviously my statement does exactly hold a lot of weight. I'm actually glad to hear what you just said; it will keep my hopes up that I will find another language I might enjoy to work with. Smile | :)

- Nick Parker
My Blog

Heath Stewart28-Dec-03 9:28

28-Dec-03 9:28

What did I say to make you think you'd enjoy it? Laugh | :laugh:

Nick Parker28-Dec-03 9:35

28-Dec-03 9:35

Well, you didn't confirm that it sucks which is a good thing. Big Grin | :-D

Who knows, I may just despise it. Roll eyes | :rolleyes:

- Nick Parker
My Blog

Heath Stewart28-Dec-03 8:52

28-Dec-03 8:52

.NET code doesn't technically, either. It uses a bit in the executable's PE/COFF header that the app loader checks (or any other various hosts, like mscoree.dll or Internet Explorer) that sets up the host runtime and loads the application. With Java, it is the java executable that does this. The only difference is that in Windows, the executable is still loaded by the app loader than makes this check. On *nix with Mono, for example, you have to run .NET applications just like java: mono MyApp.exe

Hosting ActiveX

Wizard_0128-Dec-03 2:30

Wizard_01

28-Dec-03 2:30

MSWord can load ActiveX and host ActiveX's toolbars, status bar and so on. Could any one tell me how can I host that ActiveX and create ActiveX in .NET ? And then load my controls as "Objects" in Word ?

Wizard_01

Re: Hosting ActiveX

Heath Stewart28-Dec-03 3:58

28-Dec-03 3:58

Read Nick Parker's article, Creating a CCW...[^]. You should also read the System.Runtime.InteropServices documentation so you understand what's going on. Knowledge of COM is also helpful, such as understand the difference between IUnknown and IDispatch (for automation), knowing which IPersist* interfaces that Word supports (it is a typical ActiveX container), knowing what ActiveX containers are, and the like. You should also NEVER use auto-generated class interfaces (as I asked Nick to add to his article) and NEVER change your class interface after releasing your component (instead, create a new interface by appending 2, 3, etc. for each version) that derives from the first and adds methods with new DispIdAttributes for automation objects).

As far as OLE is concerned (for hosting toolbars, merging menus, hosting status bars, etc.), you'd really be best writing your component(s) in C++ as opposed to some .NET language like C# because you'll have to define LOTS of COM interfaces with the appropriate GuidAttributes, DispIdAttributes, InterfaceTypeAttributes, and so on. System.Runtime.InteropServices provides a few managed definitions (the interfaces that start with UCOM* like UCOMIBindCtx).

filtering properties

Roger Alsing28-Dec-03 1:34

Roger Alsing

28-Dec-03 1:34

Hi,
i want to filter the properties on my component based on the value on another property.

if i set the property ".type=abc" i want to display some propps
and if i set ".type=def" i want to show some other propps

and so on.

i tried to add a designer and use the pre/postfilterproperties but those methods only fired once , when you first show the component in the propertybrowser

i need something that can tell the propertybrowser that it should show a new set of propps..

ive found some info about ifilterprovider something , but i havent found any actual code that shows how to do this..

any ideas?

(im not trying to change _all_ propps , i just want to hide propps like ".image" and ".checked" when certain criterias are met)

//Roger

Wizard_0128-Dec-03 2:53

Wizard_01

28-Dec-03 2:53

To hide properties you can use attribute [Browsable(false)]. I am not sure if is possible to change this value in runtime. I think you cannot.

Or you can implement TypeConverter for your class using attribute TypeConverterAttribute and than override GetProperties and GetPropertiesSupported method. By this way you can manage properties which will be "visible" in PropertyBrowser.

Wizard_01

Roger Alsing28-Dec-03 3:37

Roger Alsing

28-Dec-03 3:37

the typeconverter thing did it..
works like a charm..

incase anyone ever need this , here is the code for it..

public override System.ComponentModel.PropertyDescriptorCollection GetProperties(System.ComponentModel.ITypeDescriptorContext context, object value, System.Attribute[] attributes)<br />
{<br />
	System.ComponentModel.PropertyDescriptorCollection propps=propps=System.ComponentModel.TypeDescriptor.GetProperties (value,attributes,false);<br />
<br />
	ArrayList arr=new ArrayList (propps);<br />
<br />
	//cast the value to a typed TextBoxButton <br />
	TextBoxButton tb=value as TextBoxButton;<br />
	<br />
	//check what type the button is (spin,custom,checkbox)<br />
	if (tb.Type != TextBoxButtonType.Custom)<br />
		arr.Remove (propps.Find("image",true));<br />
<br />
	if (tb.Type != TextBoxButtonType.CheckBox)<br />
		arr.Remove (propps.Find("checked",true));<br />
<br />
	if (tb.Type != TextBoxButtonType.Spin)<br />
		arr.Remove (propps.Find("autorepeat",true));<br />
<br />
	//copy the modified propp arr into a typed propertydescriptor[] <br />
	PropertyDescriptor[] arr2=new PropertyDescriptor[arr.Count];<br />
	arr.CopyTo (arr2);<br />
<br />
	//return the new propertydescriptorcollection<br />
	return new PropertyDescriptorCollection(arr2);<br />
}

Wizard_0128-Dec-03 4:07

Wizard_01

28-Dec-03 4:07

Did you override TypeConverter.GetPropertiesSupported ? It has to return true !

Wizard_01

Roger Alsing28-Dec-03 4:34

Roger Alsing

28-Dec-03 4:34

yes i did , forgot to paste that part only :P

anyway , very cool stuff.
thanks

//Roger

Heath Stewart28-Dec-03 3:38

Salted Hash add vulnerabilities

28-Dec-03 3:38

Wizard_01 wrote:
To hide properties you can use attribute [Browsable(false)]. I am not sure if is possible to change this value in runtime. I think you cannot.

You can by implementing your own PropertyDescriptor or using an ICusotmTypeDescriptor on your component. Using this approach or adding PropertyDescriptors using your designer is more favorable than a TypeConverter. While TypeConverters can do that, they are typically not used for this purpose.

laphijia27-Dec-03 23:15

laphijia

27-Dec-03 23:15

I was going through the process of deciding how to store my passwords in a SQL Server database.

I was using the basic hashing approach when I came through the idea of trying with salted hashes.

When using normal hashed I didn't need to retrieve the password from the database. What I would do was to use a stored procedure like this.

CREATE PROCEDURE [dbo].[proc_authenticate]
(
@UserID nvarchar(16),
@Password nvarchar(64),
@SessionVariable nvarchar(64)
)
AS

DECLARE @AuthUserId nvarchar (16)
SET @AuthUserId = (SELECT UserId FROM Users WHERE (UserID = @UserID AND Password = @Password))

-- IF ABOVE SELECT RETURN ONLY ONE ROW THEN STORE SESSION VARIABLE IN LOCALS TABLE ELSE RETURN

IF @AuthUserId = null
RETURN

UPDATE Locals
SET
SessionVariable = @SessionVariable,
LastLoginDate = GETDATE()
WHERE (UserID = @UserID)
GO

Basically in my application I would ask the user for a username and password. Then I would generate a random session variable.
I send everything to the stored procedure on SQL Server.

It's the stored procedure that does all the authentication and there is no way to read a password if not by compromising SQL Server and gaining SA privileges.

On the other hand the approach with salted hashes is different.

1- Retrieve the stored password and the salt for an user using a stored procedure.
2- Extract salt
3- Calculate salted hash of user provided password
4- Compare stored password with user provided
5- If they are the same call a stored procedure that given UserID writes a ticket in the database.

Step one means basically giving away the User table to anybody that can steal our connection string.

This in my opinion is a security problem because basically just by cracking the user of our connection string we can retrieve any password from any user. Of course it's hashed and salted and the malicious user has to guess a username but he can use a brute force attack to decode a password.

With the previous approach instead to use brute force attack he would have had to call the sored procedure once for every attempt. This would have slowed him down and would leave a trace in our logs of a suspect activity.

But since we cannot autheniticate from inside a stored procedure using Salted Hashes we have to retrieve the password. In this case an attacker can perform the brute force attack on his own computer without any delay from accessing our server through the internet and without leavin any trace.

Step five is even worst because one can just bypass the whole authentication system and authenticate himself. Of course we might sign our tickets using a keyed hash using the server private key so that the attacked cannot just generate a ticket.

What are your opinions to this approach. I have to say that I didn't come up with this but read it in Wrox C# Data Security Handbook so I'm surprised that a tested procedure seems so weak to me.

Edd

Re: Salted Hash add vulnerabilities

Heath Stewart28-Dec-03 3:34

How to use array update the xml file?███

28-Dec-03 3:34

Even comprimising your SQL Server system would not yield the password if using a digest algorithm like MD5 or SHA1 without using a brute force attack. You make a good point about avoid such an attack, though.

Encrypting the ticket is definitely a good idea. Take a look at my article Role-based Security with Forms Authentication[^] for a brief mention of using FormsAuthentication.Encrypt to encrypt a forms authentication-based ticket. Doing this manually would work as well, but I thought I'd just mention it.

As far as using a salted hash, storing the salt makes your system little more secure than the first method of using an unsalted hash. If a cracker comprimised your system, nothing is stopping them from discovering the hash. The MD5-digest authentication mechanisms that many HTTP daemons support - as well as many browsers - actually generate a salt of sorts that it communicates with the browser (handshaking) and they use that to digest the credentials. Unfortunately, you can't do that because you need your salt to be persistent.

So, instead of storing the salt in the SQL Server, what about storing it in a different medium? You could, for example, keep an XML document (or even a simple text file) up-to-date with users and salts and read that into memory (use ASP.NET's Cache - if applicable - for some good event-based page validation). If a user comprimised the SQL Server, that cracker would have to comprise the entire system as well so that they could - most likely - gain debugging rights in order to insert their code into the ASP.NET worker process space and read the memory directly. This is just an example off the top of my head, but conceptually something you might want to consider.

nichen100127-Dec-03 20:19

nichen1001

27-Dec-03 20:19

there is a xml file: price.xml
<price>
<comdt>
<Tname id=0>AAA</Tname>
<Tprice>0</Tprice>
</comdt>
<comdt>
<Tname id=1>BBB</Tname>
<Tprice>0</Tprice>
</comdt>
</price>

the price is null,
now I have a array,arrprice(i),
arrprice(0) is AAA's price,
arrprice(1) is BBB's price,
How to use the arrprice(i) update the xml file?

I tried this way,

For x = 0 To 1
Set objprice = objDom.SelectSingleNode("//price/comdt"&[x]&"/Tprice")
objprice.Text = arrprice(x)

but it doesn't work.
Smile | :)

Thank you!

Re: How to use array update the xml file?

Nick Parker28-Dec-03 3:19