Category Archives: Applications Development

What does it take to develop an application that makes it in today’s predominantly open source world.

MAPI Without GetProcAddress

If you have ever worked with extended MAPI I am sure that you have come across the need to use the win32 API function GetProcAddress. There is now a stub library over at codeplex and some sample code to show you how to get started with Office 2010 or 2007. The project includes sources if you are interested in seeing how it is built. In addition, for those looking for more comprehensive MAPI code samples, there is a really in depth sample at codeplex as well Called: MFCMAPI

MapiStubLibrary

.Net Trimming Whitespace in an image

In case you wanted to know, it’s not quite that difficult to trim pure white pixels from an image in .net. The crux of the problem is really getting access to the color data and understanding what you are looking at when you have it. I will be demonstrating a method using 24 bits per pixel images only, but the concepts can be applied to other types.
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Dot Net html editor to image

Dot Net html editor to image

While working on a commercial project, I was involved in providing a simple html rendering engine. Simple in terms of not being 100% complete, not necessarily in complexity. To help debug this, I created a sample app that demonstrates the workings of an html editor and the rendering in action.

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Reusing the WebBrowser Control

Reusing the WebBrowser Control

I have found the need in several projects as of late to reuse the WebBrowser Control in .net  languages such as c#/vb.net. I have not ventured into the j# domain, but I have also played around with c++.net a little bit for various projects. There are a couple of things to keep in mind when reusing the control in different scenarios – most of which for my purposes do not include in a windows form for display purposes. For the most part making sure that there is a reference to System.Windows.Forms dll is in your References and making sure that the using or imports statements are also included this is a good first start.

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Unexpected Error Adding new Data Connection in Visual Studio

Unexpected Error Adding new Data Connection in Visual Studio

Recently I was adding a Data Connection in Visual Studio, and I found that I kept getting an error message box whenever I tried.

There were a number of suggestions such as:

devenv.exe /reset

and doing a repair install which didn’t work.

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Where to find sos.dll

Where to find sos.dll

If you are looking where to find sos.dll, please check the following locations before you download windebug tools:

C:\Windows\Microsoft.NET\Framework\v2.0.50727
C:\Windows\Microsoft.NET\Framework\v4.0.30319

For Details on why this may be missing in other framework versions see:

This post

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Sqlite Hashing Functions Library

Looking for Sqlite Hashing Functions Library? Look No Further!

I have found a way to quite easily use the existing digest functions provided by OpenSSL. I have successfully been able to compile and run this on Solaris 10×86 and I think that as long as you have a current ssl implementation, this should work quite well. I have not thoroughly tested everything however, but have repeated the EVP_ function code pattern found here. This pattern is very simple and easy to use. I have also used a code pattern for a sample Sqlite3 Extension from here. As it is, the documentation is good enough to perform the simple task a few times and at a minimum for my implementation include these algorithms: md2, md5, sha, sha1, ripemd160.


Code Pattern for the Sqlite Extension

static void [function_name](
    sqlite3_context *context,
    int argc,
    sqlite3_value **argv
){
        unsigned char md_value[EVP_MAX_MD_SIZE];
        int md_len,i;
        if ( argc != 1 ){
                sqlite3_result_null(context);
                return ;
        }
        EVP_MD_CTX ctx  ;
        EVP_MD_CTX_init(&ctx);
        if(EVP_DigestInit_ex(&ctx,EVP_[function_name](),NULL)){
                char * input = 0 ;
                char * output = 0 ;
                input = ( char * ) sqlite3_value_text(argv[0]);
                EVP_DigestUpdate(&ctx, input, strlen(input));
                EVP_DigestFinal_ex(&ctx,md_value,&md_len);
                output = ( char * ) malloc ( md_len * 2 + 1 );
                if ( !output ){
                        sqlite3_result_null(context);
                        EVP_MD_CTX_cleanup(&ctx);
                        return ;
                }
                for (i = 0; i < md_len; i++){
                        sprintf (&output[i*2],"%02x", (unsigned char)md_value[i]);
                }
                sqlite3_result_text(context,output,strlen(output),(void*)-1);
                free(output);
                output=0;
        }else{
                sqlite3_result_null(context);
        }
        EVP_MD_CTX_cleanup(&ctx);
}

Sqlite Init Function

int sqlite3_extension_init(
  sqlite3 *db,
  char **pzErrMsg,
  const sqlite3_api_routines *pApi
){
  SQLITE_EXTENSION_INIT2(pApi)
  sqlite3_create_function(db, "md2", 1, SQLITE_ANY, 0, md2, 0, 0);
  sqlite3_create_function(db, "md5", 1, SQLITE_ANY, 0, md5, 0, 0);
  sqlite3_create_function(db, "sha", 1, SQLITE_ANY, 0, sha, 0, 0);
  sqlite3_create_function(db, "sha1", 1, SQLITE_ANY, 0, sha1, 0, 0);
// ** Not Used as it didn't seem to be available in my OpenSSL
//  sqlite3_create_function(db, "mdc2", 1, SQLITE_ANY, 0, mdc2, 0, 0);
  sqlite3_create_function(db, "ripemd160", 1, SQLITE_ANY, 0, ripemd160, 0, 0);
  return 0;
}

Command Line Used for Compilation

The command line I used to compile was quite simple and just needed to include the -lssl .

gcc  -shared -fPIC -Isqlite3 -lssl  -o sqlite_digest.ext sqlite_digest.c

My set up includes sqlite and openssl in my include path so there may be issues if this is not your set up.

Loading the library in Sqlite

To load the library in Sqlite, you simply need to run the command line version as follows:

sqlite3 [optional database name]
sqlite>SELECT load_extension('./sqlite_digest.ext');
sqlite>SELECT md2('test');
dd34716876364a02d0195e2fb9ae2d1b
sqlite>SELECT md5('test');
098f6bcd4621d373cade4e832627b4f6
sqlite>SELECT sha('test');
f8d3b312442a67706057aeb45b983221afb4f035
sqlite>SELECT sha1('test');
a94a8fe5ccb19ba61c4c0873d391e987982fbbd3
sqlite>SELECT ripemd160('test');
5e52fee47e6b070565f74372468cdc699de89107

Source Code

New Updated Link
Source Code to Sqlite Hashing Functions Library
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