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• What is the right approach to checksumming UDP packets

  - by mr.b

  I'm building UDP server application in C#. I've come across a packet checksum problem. As you probably know, each packet should carry some simple way of telling receiver if packet data is intact. Now, UDP already has 2-byte checksum as part of header, which is optional, at least in IPv4 world. Alternative method is to have custom checksum as part of data section in each packet, and to verify it on receiver. My question boils down to: is it better to rely on (optional) checksum in UDP packet header, or to make a custom checksum implementation as part of packet data section? Perhaps the right answer depends on circumstances (as usual), so one circumstance here is that, even though code is written and developed in .NET on Windows, it might have to run under platform-independent Mono.NET, so eventual solution should be compatible with other platforms. I believe that custom checksum algorithm would be easily portable, but I'm not so sure about the first one. Any thoughts? Also, shouts about packet checksumming in general are welcome.

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• Create image from scratch with JMagick

  - by Michael IV

  I am using Java port of ImageMagick called JMagick .I need to be able to create a new image and write an arbitrary text chunk into it.The docs are very poor and what I managed to get so far is to write text into the image which comes from IO.Also , in all the examples I have found it seems like the very first operation ,before writing new image data , is always loading of an existing image into ImageInfo instance.How do I create an image from scratch with JMagick and then write a text into it? Here is what I do now : try { ImageInfo info = new ImageInfo(); info.setSize("512x512"); info.setUnits(ResolutionType.PixelsPerInchResolution); info.setColorspace(ColorspaceType.RGBColorspace); info.setBorderColor(PixelPacket.queryColorDatabase("red")); info.setDepth(8); BufferedImage img = new BufferedImage(512,512,BufferedImage.TYPE_4BYTE_ABGR); byte[] imageBytes = ((DataBufferByte) img.getData().getDataBuffer()).getData(); MagickImage mimage = new MagickImage(info,imageBytes); DrawInfo aInfo = new DrawInfo(info); aInfo.setFill(PixelPacket.queryColorDatabase("green")); aInfo.setUnderColor(PixelPacket.queryColorDatabase("yellow")); aInfo.setOpacity(0); aInfo.setPointsize(36); aInfo.setFont("Arial"); aInfo.setTextAntialias(true); aInfo.setText("JMagick Tutorial"); aInfo.setGeometry("+40+40"); mimage.annotateImage(aInfo); mimage.setFileName("text.jpg"); mimage.writeImage(info); } catch (MagickException ex) { Logger.getLogger(LWJGL_IDOMOO_SIMPLE_TEST.class.getName()).log(Level.SEVERE, null, ex); } It doesn't work , the JVM crashes with access violation as it probably expects for the input image from IO.

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• How close can I get C# to the performance of C++ for small intensive tasks?

  - by SLC

  I was thinking about the speed difference of C++ to C# being mostly about C# compiling to byte-code that is taken in by the JIT compiler (is that correct?) and all the checks C# does. I notice that it is possible to turn a lot of these functions off, both in the compile options, and possibly through using the unsafe keyword as unsafe code is not verifiable by the common language runtime. Therefore if you were to write a simple console application in both languages, that flipped an imaginary coin an infinite number of times and displayed the results to the screen every 10,000 or so iterations, how much speed difference would there be? I chose this because it's a very simple program. I'd like to test this but I don't know C++ or have the tools to compile it. This is my C# version though: static void Main(string[] args) { unsafe { Random rnd = new Random(); int heads = 0, tails = 0; while (true) { if (rnd.NextDouble() > 0.5) heads++; else tails++; if ((heads + tails) % 1000000 == 0) Console.WriteLine("Heads: {0} Tails: {1}", heads, tails); } } } Is the difference enough to warrant deliberately compiling sections of code "unsafe" or into DLLs that do not have some of the compile options like overflow checking enabled? Or does it go the other way, where it would be beneficial to compile sections in C++? I'm sure interop speed comes into play too then. To avoid subjectivity, I reiterate the specific parts of this question as: Does C# have a performance boost from using unsafe code? Do the compile options such as disabling overflow checking boost performance, and do they affect unsafe code? Would the program above be faster in C++ or negligably different? Is it worth compiling long intensive number-crunching tasks in a language such as C++ or using /unsafe for a bonus? Less subjectively, could I complete an intensive operation faster by doing this?

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• Java Performance measurement

  - by portoalet

  Hi, I am doing some Java performance comparison between my classes, and wondering if there is some sort of Java Performance Framework to make writing performance measurement code easier? I.e, what I am doing now is trying to measure what effect does it have having a method as "synchronized" as in PseudoRandomUsingSynch.nextInt() compared to using an AtomicInteger as my "synchronizer". So I am trying to measure how long it takes to generate random integers using 3 threads accessing a synchronized method looping for say 10000 times. I am sure there is a much better way doing this. Can you please enlighten me? :) public static void main( String [] args ) throws InterruptedException, ExecutionException { PseudoRandomUsingSynch rand1 = new PseudoRandomUsingSynch((int)System.currentTimeMillis()); int n = 3; ExecutorService execService = Executors.newFixedThreadPool(n); long timeBefore = System.currentTimeMillis(); for(int idx=0; idx<100000; ++idx) { Future<Integer> future = execService.submit(rand1); Future<Integer> future1 = execService.submit(rand1); Future<Integer> future2 = execService.submit(rand1); int random1 = future.get(); int random2 = future1.get(); int random3 = future2.get(); } long timeAfter = System.currentTimeMillis(); long elapsed = timeAfter - timeBefore; out.println("elapsed:" + elapsed); } the class public class PseudoRandomUsingSynch implements Callable<Integer> { private int seed; public PseudoRandomUsingSynch(int s) { seed = s; } public synchronized int nextInt(int n) { byte [] s = DonsUtil.intToByteArray(seed); SecureRandom secureRandom = new SecureRandom(s); return ( secureRandom.nextInt() % n ); } @Override public Integer call() throws Exception { return nextInt((int)System.currentTimeMillis()); } } Regards

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• Avoiding GC thrashing with WSE 3.0 MTOM service

  - by Leon Breedt

  For historical reasons, I have some WSE 3.0 web services that I cannot upgrade to WCF on the server side yet (it is also a substantial amount of work to do so). These web services are being used for file transfers from client to server, using MTOM encoding. This can also not be changed in the short term, for reasons of compatibility. Secondly, they are being called from both Java and .NET, and therefore need to be cross-platform, hence MTOM. How it works is that an "upload" WebMethod is called by the client, sending up a chunk of data at a time, since files being transferred could potentially be gigabytes in size. However, due to not being able to control parts of the stack before the WebMethod is invoked, I cannot control the memory usage patterns of the web service. The problem I am running into is for file sizes from 50MB or so onwards, performance is absolutely killed because of GC, since it appears that WSE 3.0 buffers each chunk received from the client in a new byte[] array, and by the time we've done 50MB we're spending 20-30% of time doing GC. I've played with various chunk sizes, from 16k to 2MB, with no real great difference in results. Smaller chunks are killed by the latency involved with round-tripping, and larger chunks just postpone the slowdown until GC kicks in. Any bright ideas on cutting down on the garbage created by WSE? Can I plug into the pipeline somehow and jury-rig something that has access to the client's request stream and streams it to the WebMethod? I'm aware that it is possible to "stream" responses to the client using WSE (albeit very ugly), but this problem is with requests from the client.

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• Fun things you can do by mutating Java strings

  - by polygenelubricants

  So I've come around since I asked how to limit setAccessible to only “legitimate” uses and have come to embrace its power for fun. Enabled by its power, of course, is string mutation. import java.lang.reflect.Field; public class Mutator { static void mutate(Object obj, String field, Object newValue) { try { Field f = obj.getClass().getDeclaredField(field); f.setAccessible(true); f.set(obj, newValue); } catch (Exception e) { } } public static void mutate(String from, String to) { mutate(from, "value", to.toCharArray()); mutate(from, "count", to.length()); } public static void main(String args[]) { Mutator.mutate(System.getProperty("line.separator"), "<br/>\n"); System.out.println("Hello world!"); Mutator.mutate(Integer.toString(Integer.MIN_VALUE), "OMG!"); System.out.println(-2147483648); Mutator.mutate(String.valueOf((Object) null), "LOL!"); System.out.println(Arrays.toString(new int[3][])); Mutator.mutate(Arrays.toString(new int[0]), ":("); System.out.println(Arrays.toString(new byte[0])); } } Output (if no exception is thrown): Hello world!<br/> OMG!<br/> [LOL!, LOL!, LOL!]<br/> :(<br/> Let's see what other fun things we can come up with.

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• how to initialize and implement the matrix inside the function in objective-C?

  - by Rajendra Bhole

  Hi, I want to develop an application in which i want to be initialize the matrix for manipulation. The code as follows, struct pixel { Byte r, g, b,a; int count; }; (NSInteger) processImage1: (UIImage*) image { struct pixel* pixels = (struct pixel*) calloc(1, image.size.width * image.size.height * sizeof(struct pixel)); if (pixels != nil) { // Create a new bitmap CGContextRef context = CGBitmapContextCreate( (void*) pixels, image.size.width, image.size.height, 8, image.size.width * 4, CGImageGetColorSpace(image.CGImage), kCGImageAlphaPremultipliedLast ); if (context != NULL) { // Draw the image in the bitmap CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, image.size.width, image.size.height), image.CGImage); NSUInteger numberOfPixels = image.size.width * image.size.height; while (numberOfPixels &gt; 0) { if (pixels->r == 254 || pixels->g == 77 || pixels->b==254) { numberOfRedPixels++; } pixels++; numberOfPixels--; } CGContextRelease(context); } free(pixels); } return 1; } I want to implement the matrix inside the function of - (NSInteger) processImage1: (UIImage*) image {} The matrix should have be row = image.size.width and column = image.size.height.

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• Json HTTP Module stream issue

  - by Justin

  Hey, I have an HTTP Module that I use to clean up the JSON returned by my web service (see http://www.codeproject.com/KB/webservices/ASPNET_JSONP.aspx?msg=3400287#xx3400287xx for an example of this.) Basically it relates to calling cross-domain JSON web services from javascript. There is this JsonHttpModule which uses a JsonResponseFilter Stream class to write out the JSON and the overloaded Write method is supposed to wrap the name of the callback function around the JSON, otherwise the JSON errors out as needing a label. However, if the JSON is really long, the Write method in the Stream class is called multiple times, causing the callback function to incorrectly get inserted midway through the JSON. Is there a way in the Stream class to wrap the callback function around the stream at the end or to specify that it write all of the JSON in 1 Write method instead of in chunks?? Here's where it calls the JsonResponseFilter in the JsonHttpModule: public void OnReleaseRequestState(object sender, EventArgs e) { HttpApplication app = (HttpApplication)sender; if (!_Apply(app.Context.Request)) return; // apply response filter to conform to JSONP app.Context.Response.Filter = new JsonResponseFilter(app.Context.Response.Filter, app.Context); } Here's the Write method in the JsonResponseFilter Stream class that gets called multiple times: public override void Write(byte[] buffer, int offset, int count) { var b1 = Encoding.UTF8.GetBytes(_context.Request.Params["callback"] + "("); _responseStream.Write(b1, 0, b1.Length); _responseStream.Write(buffer, offset, count); var b2 = Encoding.UTF8.GetBytes(");"); _responseStream.Write(b2, 0, b2.Length); } Thanks for any help! Justin

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• LPCSTR, TCHAR, String

  - by user285327

  I am use next type of strings: LPCSTR, TCHAR, String i want to convert: 1) from TCHAR to LPCSTR 2) from String to char I convert from TCHAR to LPCSTR by that code: RunPath = TEXT("C:\\1"); LPCSTR Path = (LPCSTR)RunPath; From String to char i convert by that code: SaveFileDialog^ saveFileDialog1 = gcnew SaveFileDialog; saveFileDialog1->Title = "?????????? ?????-????????"; saveFileDialog1->Filter = "bck files (*.bck)|*.bck"; saveFileDialog1->RestoreDirectory = true; pin_ptr<const wchar_t> wch = TEXT(""); if ( saveFileDialog1->ShowDialog() == System::Windows::Forms::DialogResult::OK ) { wch = PtrToStringChars(saveFileDialog1->FileName); } else return; ofstream os(wch, ios::binary); My problem is that when i set "Configuration Properties - General Character Set in "Use Multi-Byte Character Set" the first part of code work correctly. But the second part of code return error C2440. When i set "Configuration Properties - General Character Set in "Use Unicode" the second part of code work correctly. But the first part of code return the only first character from TCHAR to LPCSTR.

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• Using A Local file path in a Streamwriter object ASP.Net

  - by Nick LaMarca

  I am trying to create a csv file of some data. I have wrote a function that successfully does this.... Private Sub CreateCSVFile(ByVal dt As DataTable, ByVal strFilePath As String) Dim sw As New StreamWriter(strFilePath, False) ''# First we will write the headers. ''EDataTable dt = m_dsProducts.Tables[0]; Dim iColCount As Integer = dt.Columns.Count For i As Integer = 0 To iColCount - 1 sw.Write(dt.Columns(i)) If i < iColCount - 1 Then sw.Write(",") End If Next sw.Write(sw.NewLine) ''# Now write all the rows. For Each dr As DataRow In dt.Rows For i As Integer = 0 To iColCount - 1 If Not Convert.IsDBNull(dr(i)) Then sw.Write(dr(i).ToString()) End If If i < iColCount - 1 Then sw.Write(",") End If Next sw.Write(sw.NewLine) Next sw.Close() End Sub The problem is I am not using the streamwriter object correctly for what I trying to accomplish. Since this is an asp.net I need the user to pick a local filepath to put the file on. If I pass any path to this function its gonna try to write it to the directory specified on the server where the code is. I would like this to popup and let the user select a place on their local machine to put the file.... Dim exData As Byte() = File.ReadAllBytes(Server.MapPath(eio)) File.Delete(Server.MapPath(eio)) Response.AddHeader("content-disposition", String.Format("attachment; filename={0}", fn)) Response.ContentType = "application/x-msexcel" Response.BinaryWrite(exData) Response.Flush() Response.End() I am calling the first function in code like this... Dim emplTable As DataTable = SiteAccess.DownloadEmployee_H() CreateCSVFile(emplTable, "C:\\EmplTable.csv") Where I dont want to have specify the file loaction (because this will put the file on the server and not on a client machine) but rather let the user select the location on their client machine. Can someone help me put this together? Thanks in advance.

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• how to make a name from random numbers?

  - by blood

  my program makes a random name that could have a-z this code makes a 16 char name but :( my code wont make the name and idk why :( can anyone show me what's wrong with this? char name[16]; void make_random_name() { byte loop = -1; for(;;) { loop++; srand((unsigned)time(0)); int random_integer; random_integer = (rand()%10)+1; switch(random_integer) { case '1': name[loop] = 'A'; break; case '2': name[loop] = 'B'; break; case '3': name[loop] = 'C'; break; case '4': name[loop] = 'D'; break; case '5': name[loop] = 'E'; break; case '6': name[loop] = 'F'; break; case '7': name[loop] = 'G'; break; case '8': name[loop] = 'Z'; break; case '9': name[loop] = 'H'; break; } cout << name << "\n"; if(loop > 15) { break; } } }

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• Changing the system time zone succeeds once and then no longer changes

  - by Adam Driscoll

  I'm using the WinAPI to set the time zone on a Windows XP SP3 box. I'm reading the time zone information from the HKLM\Software\Microsoft\WindowsNT\Time Zones\<time zone name> key and then setting the time zone to the specified time zone. I enumerate the keys under the Time Zones key, grab the TZI value and stuff it into a TIME_ZONE_INFORMATION struct to be passed to SetTimeZoneInformation. All seems to work on the first pass. The time zone changes, no error is returned. The second time I perform this operation (same user, new session, on login before userinit) the call succeeds but the system does not reflect the time zone change. Neither the clock nor time stamps on files are updated to the new time zone. When I navigate to: HKLM\System\CurrentControlSet\Control\TimeZoneInformation my new time zone information is present. A couple strange things are happening when I'm setting my time zone: Also when I parse the TZI binary value from the registry to store in my TIME_ZONE_INFORMATION struct I'm noticing the struct has the DaylightDate.wDay and StandardDate.wDay field always set to 0 I tried to call GetTimeZoneInformation right after I call SetTimeZoneInformation but the call fails with a 1300 error (Not all privileges or groups referenced are assigned to the caller. ) I'm also making sure to send a WM_BROADCAST message so Explorer knows whats going on. Think it's the parsing of the byte array to the TIME_ZONE_INFORMATION struct? Or am I missing some thing else important? EDIT: Found a document stating why this is happening: here. Privilege was introduced in Vista...thanks MSDN docs... Per the Microsoft documentation I'm enabling the SE_TIME_ZONE_NAME privilege for the current processes token. But when I attempt to call LookupPriviledgeValue for SE_TIME_ZONE_NAME I get a 1313 error (A specified privilege does not exist. ).

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• Encryption puzzle / How to create a ProxyStub for a Remote Assistance ticket

  - by Jon Clegg

  I am trying to create a ticket for Remote Assistance. Part of that requires creating a PassStub parameter. As of the documenation: http://msdn.microsoft.com/en-us/library/cc240115(PROT.10).aspx PassStub: The encrypted novice computer's password string. When the Remote Assistance Connection String is sent as a file over e-mail, to provide additional security, a password is used.<16 In part 16 they detail how to create as PassStub. In Windows XP and Windows Server 2003, when a password is used, it is encrypted using PROV_RSA_FULL predefined Cryptographic provider with MD5 hashing and CALG_RC4, the RC4 stream encryption algorithm. As PassStub looks like this in the file: PassStub="LK#6Lh*gCmNDpj" If you want to generate one yourself run msra.exe in Vista or run the Remote Assistance tool in WinXP. The documentation says this stub is the result of the function CryptEncrypt with the key derived from the password and encrypted with the session id (Those are also in the ticket file). The problem is that CryptEncrypt produces a binary output way larger then the 15 byte PassStub. Also the PassStub isn't encoding in any way I've seen before. Some interesting things about the PassStub encoding. After doing statistical analysis the 3rd char is always a one of: !#$&()+-=@^. Only symbols seen everywhere are: *_ . Otherwise the valid characters are 0-9 a-z A-Z. There are a total of 75 valid characters and they are always 15 bytes. Running msra.exe with the same password always generates a different PassStub, indicating that it is not a direct hash but includes the rasessionid as they say. Some other ideas I've had is that it is not the direct result of CryptEncrypt, but a result of the rasessionid in the MD5 hash. In MS-RA (http://msdn.microsoft.com/en-us/library/cc240013(PROT.10).aspx). The "PassStub Novice" is simply hex encoded, and looks to be the right length. The problem is I have no idea how to go from any hash to way the ProxyStub looks like.

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• Need help in tuning a sql-query

  - by Viper

  Hello, i need some help to boost this SQL-Statement. The execution time is around 125ms. During the runtime of my program this sql (better: equally structured sqls for different tables) will be called 300.000 times. The average row count in the tables lies around 10.000.000 rows and new rows (updates/inserts) will be added with a timestamp each day. Data which are interesting for this particular export-program lies in the last 1-3 days. Maybe this is helpful for an index to create. The data i need is the current valid row for a given id and the forerunner datarow to get the updates (if exists). We use a Oracle 11g database and Dot.Net Framework 3.5 SQL-Statement to boost: select ID_SOMETHING, -- Number(12) ID_CONTRIBUTOR, -- Char(4 Byte) DATE_VALID_FROM, -- DATE DATE_VALID_TO -- DATE from TBL_SOMETHING XID where ID_SOMETHING = :ID_INSTRUMENT and ID_CONTRIBUTOR = :ID_CONTRIBUTOR and DATE_VALID_FROM <= :EXPORT_DATE and DATE_VALID_TO >= :EXPORT_DATE order by DATE_VALID_FROM asc; Here i uploaded the current Explain-Plan for this query. I'm not a database expert so i don't know which index-type would fit best for this requirement. I have seen that there are many different possible index-types which could be applied. Maybe Oracle Optimizer Hints are helpful, too. Does anyone has a good idea for tuning this sql or can point me in a right direction?

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• In .NET, What Is Fastest Way to Initialize Multi-Dimensional Array to Non-Default Value

  - by AMissico

  How do I initialize a multi-dimensional array of a primitive type as fast as possible? I am stuck with using multi-dimensional arrays. My problem is performance. The following routine initializes a 100x100 array in approx. 500 ticks. Removing the int.MaxValue initialization results in approx. 180 ticks just for the looping. Approximately 100 ticks to create the array without looping and without initializing to int.MaxValue. Routines similiar to this are called a few tens-of-thousands to several million times. I am open to suggestions on how to optimize this non-default initialization of an array. One idea I had is to use a smaller primitive type when available. For instance, using byte instead of int, saves 100 ticks. I would be happy with this, but I am hoping that I don't have to change the primitive data type. public int[,] CreateArray(Size size) { int[,] array = new int[size.Width, size.Height]; for (int x = 0; x < size.Width; x++) { for (int y = 0; y < size.Height; y++) { array[x, y] = int.MaxValue; } } return array; }

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• How to send a JSONObject to a REST service?

  - by Sebi

  Retrieving data from the REST Server works well, but if I want to post an object it doesn't work: public static void postJSONObject(int store_type, FavoriteItem favorite, String token, String objectName) { String url = ""; switch(store_type) { case STORE_PROJECT: url = URL_STORE_PROJECT_PART1 + token + URL_STORE_PROJECT_PART2; //data = favorite.getAsJSONObject(); break; } HttpClient httpClient = new DefaultHttpClient(); HttpPost postMethod = new HttpPost(url); try { HttpEntity entity = new StringEntity("{\"ID\":0,\"Name\":\"Mein Projekt10\"}"); postMethod.setEntity(entity); HttpResponse response = httpClient.execute(postMethod); Log.i("JSONStore", "Post request, to URL: " + url); System.out.println("Status code: " + response.getStatusLine().getStatusCode()); } catch (ClientProtocolException e) { I always get a 400 Error Code. Does anybody know whats wrong? I have working C# code, but I can't convert: System.Net.WebRequest wr = System.Net.HttpWebRequest.Create("http://localhost:51273/WSUser.svc/pak3omxtEuLrzHSUSbQP/project"); wr.Method = "POST"; string data = "{\"ID\":1,\"Name\":\"Mein Projekt\"}"; byte [] d = UTF8Encoding.UTF8.GetBytes(data); wr.ContentLength = d.Length; wr.ContentType = "application/json"; wr.GetRequestStream().Write(d, 0, d.Length); System.Net.WebResponse wresp = wr.GetResponse(); System.IO.StreamReader sr = new System.IO.StreamReader(wresp.GetResponseStream()); string line = sr.ReadToEnd();

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• Help needed in grokking password hashes and salts

  - by javafueled

  I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

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• How is conversion of float/double to int handled in printf?

  - by Sandip

  Consider this program int main() { float f = 11.22; double d = 44.55; int i,j; i = f; //cast float to int j = d; //cast double to int printf("i = %d, j = %d, f = %d, d = %d", i,j,f,d); //This prints the following: // i = 11, j = 44, f = -536870912, d = 1076261027 return 0; } Can someone explain why the casting from double/float to int works correctly in the first case, and does not work when done in printf? This program was compiled on gcc-4.1.2 on 32-bit linux machine. EDIT: Zach's answer seems logical, i.e. use of format specifiers to figure out what to pop off the stack. However then consider this follow up question: int main() { char c = 'd'; // sizeof c is 1, however sizeof character literal // 'd' is equal to sizeof(int) in ANSI C printf("lit = %c, lit = %d , c = %c, c = %d", 'd', 'd', c, c); //this prints: lit = d, lit = 100 , c = d, c = 100 //how does printf here pop off the right number of bytes even when //the size represented by format specifiers doesn't actually match //the size of the passed arguments(char(1 byte) & char_literal(4 bytes)) return 0; } How does this work?

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• Display post data !

  - by Comii

  I am trying to post data from vb.net application to web service asmx that is located on server! For posting data from vb.net application I am using this code: Public Function Post(ByVal url As String, ByVal data As String) As String Dim vystup As String = Nothing Try 'Our postvars Dim buffer As Byte() = Encoding.ASCII.GetBytes(data) 'Initialisation, we use localhost, change if appliable Dim WebReq As HttpWebRequest = DirectCast(WebRequest.Create(url), HttpWebRequest) 'Our method is post, otherwise the buffer (postvars) would be useless WebReq.Method = "POST" 'We use form contentType, for the postvars. WebReq.ContentType = "application/x-www-form-urlencoded" 'The length of the buffer (postvars) is used as contentlength. WebReq.ContentLength = buffer.Length 'We open a stream for writing the postvars Dim PostData As Stream = WebReq.GetRequestStream() 'Now we write, and afterwards, we close. Closing is always important! PostData.Write(buffer, 0, buffer.Length) PostData.Close() 'Get the response handle, we have no true response yet! Dim WebResp As HttpWebResponse = DirectCast(WebReq.GetResponse(), HttpWebResponse) 'Let's show some information about the response Console.WriteLine(WebResp.StatusCode) Console.WriteLine(WebResp.Server) 'Now, we read the response (the string), and output it. Dim Answer As Stream = WebResp.GetResponseStream() Dim _Answer As New StreamReader(Answer) 'Congratulations, you just requested your first POST page, you 'can now start logging into most login forms, with your application 'Or other examples. vystup = _Answer.ReadToEnd() Catch ex As Exception MessageBox.Show(ex.Message) End Try Return vystup.Trim() & vbLf End Function Now how i can retrieve this data in asmx service?

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• Encryption puzzle / How to create a PassStub for a Remote Assistance ticket

  - by Jon Clegg

  I am trying to create a ticket for Remote Assistance. Part of that requires creating a PassStub parameter. As of the documentation: http://msdn.microsoft.com/en-us/library/cc240115(PROT.10).aspx PassStub: The encrypted novice computer's password string. When the Remote Assistance Connection String is sent as a file over e-mail, to provide additional security, a password is used.<16 In part 16 they detail how to create as PassStub. In Windows XP and Windows Server 2003, when a password is used, it is encrypted using PROV_RSA_FULL predefined Cryptographic provider with MD5 hashing and CALG_RC4, the RC4 stream encryption algorithm. As PassStub looks like this in the file: PassStub="LK#6Lh*gCmNDpj" If you want to generate one yourself run msra.exe in Vista or run the Remote Assistance tool in WinXP. The documentation says this stub is the result of the function CryptEncrypt with the key derived from the password and encrypted with the session id (Those are also in the ticket file). The problem is that CryptEncrypt produces a binary output way larger then the 15 byte PassStub. Also the PassStub isn't encoding in any way I've seen before. Some interesting things about the PassStub encoding. After doing statistical analysis the 3rd char is always a one of: !#$&()+-=@^. Only symbols seen everywhere are: *_ . Otherwise the valid characters are 0-9 a-z A-Z. There are a total of 75 valid characters and they are always 15 bytes. Running msra.exe with the same password always generates a different PassStub, indicating that it is not a direct hash but includes the rasessionid as they say. Some other ideas I've had is that it is not the direct result of CryptEncrypt, but a result of the rasessionid in the MD5 hash. In MS-RA (http://msdn.microsoft.com/en-us/library/cc240013(PROT.10).aspx). The "PassStub Novice" is simply hex encoded, and looks to be the right length. The problem is I have no idea how to go from any hash to way the PassStub looks like.

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• Unable to access Java-created file -- sometimes

  - by BlairHippo

  In Java, I'm working with code running under WinXP that creates a file like this: public synchronized void store(Properties props, byte[] data) { try { File file = filenameBasedOnProperties(props); if ( file.exists() ) { return; } File temp = File.createTempFile("tempfile", null); FileOutputStream out = new FileOutputStream(temp); out.write(data); out.flush(); out.close(); file.getParentFile().mkdirs(); temp.renameTo(file); } catch (IOException ex) { // Complain and whine and stuff } } Sometimes, when a file is created this way, it's just about totally inaccessible from outside the code (though the code responsible for opening and reading the file has no problem), even when the application isn't running. When accessed via Windows Explorer, I can't move, rename, delete, or even open the file. Under Cygwin, I get the following when I ls -l the directory: ls: cannot access [big-honkin-filename] total 0 ?????????? ? ? ? ? ? [big-honkin-filename] As implied, the filenames are big, but under the 260-character max for XP (though they are slightly over 200 characters). To further add to the sense the my computer just wants me to feel stupid, sometimes the files created by this code are perfectly normal. The only pattern I've spotted is that once one file in the directory "locks", the rest are screwed. Anybody ever run into something like this before, or have any insights into what's going on here?

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• how to login to criaglist through c#

  - by kosikiza

  i m using the following code to login to criaglist, but hav't successsed yet. string formParams = string.Format("inputEmailHandle={0}&inputPassword={1}", "[email protected]", "pakistan01"); //string postData = "[email protected]&inputPassword=pakistan01"; string uri = "https://accounts.craigslist.org/"; HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri); request.KeepAlive = true; request.ProtocolVersion = HttpVersion.Version10; request.Method = "POST"; byte[] postBytes = Encoding.ASCII.GetBytes(formParams); request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = postBytes.Length; Stream requestStream = request.GetRequestStream(); requestStream.Write(postBytes, 0, postBytes.Length); requestStream.Close(); HttpWebResponse response = (HttpWebResponse)request.GetResponse(); cookyHeader = response.Headers["Set-cookie"]; string pageSource; string getUrl = "https://post.craigslist.org/del"; WebRequest getRequest = WebRequest.Create(getUrl); getRequest.Headers.Add("Cookie", cookyHeader); WebResponse getResponse = getRequest.GetResponse(); using (StreamReader sr = new StreamReader(getResponse.GetResponseStream())) { pageSource = sr.ReadToEnd(); }

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• WPF - Why doesn't Microsoft supply a decent set of most-used controls ?

  - by IUsedToBeAPygmy

  I've been playing with WPF for some months now, and I quite like it. But one of the things I don't get is why MS doesn't put a little more effort in helping developers by supplying basic controls, and I need to get this off my chest :) For example, I figure most applications somewhere will need to let you edit some properties - for configuration or whatever. What would be the most used types in a proprety-grid editor ? text numbers (byte, float/double, int, etc) colors ....etc. So why isn't there even something as simple as a control to edit numbers ? Like a generic NumericUpDown control that allows you to type in numbers (no text, no pasting invalid input) or spin them up/down according to some given rules (decimal, floating point, min/maxvalue) ? Why isn't there a generic colorpicker, so people get the same user-experience in every application ? Why isn't there a standard implementation of a SearchTextBox, a BreadCrumb-control, or all these other standard control types users have gotten accustomed to the last 10 years ? (..but at least they DID have the time to implement a generic splashscreen - because everyone knows that greatly increases user-productivity....) The well-known ideal is always to give people the same user-experience over different applications. So even if some of those controls would be easy to make - it would be preferred to have one version over different applications. I see people all over the internet trying to do the same stuff over and over again. Okay, so MS started a WPF Toolkit project on Codeplex that tries to implement some controls, but only did so half-heartedly and is completely dead by now (last update of the roadmap dates back to Mar 21 2009). The result of this is that a lot of people starting a WPF-project end up spending a lot of time on trying to figure out how to create some generic controls and get really frustrated. Wasn't the mantra "Developers, developers, developers!" ..? /Rant

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• Uncompress a TIFF file without going through BufferedImage

  - by Gert

  I am receiving large size CCITT Group 4 compressed TIFF files that need to be written elsewhere as uncompressed TIFF files. I am using the jai_imageio TIFF reader and writer to do that and it works well as long as the product _width * height_ of the image fits in an integer. Here is the code I am using: TIFFImageReaderSpi readerSpi= new TIFFImageReaderSpi(); ImageReader imageReader = readerSpi.createReaderInstance(); byte[] data = blobManager.getObjectForIdAndVersion(id, version); ImageInputStream imageInputStream = ImageIO.createImageInputStream(data); imageReader.setInput(imageInputStream); TIFFImageWriterSpi writerSpi = new TIFFImageWriterSpi(); ImageWriter imageWriter = writerSpi.createWriterInstance(); ImageWriteParam imageWriteParam = imageWriter.getDefaultWriteParam(); imageWriteParam.setCompressionMode(ImageWriteParam.MODE_DISABLED); //bufferFile is created in the constructor ImageOutputStream imageOutputStream = ImageIO.createImageOutputStream(bufferFile); imageWriter.setOutput(imageOutputStream); //Now read the bitmap BufferedImage bufferedImage = imageReader.read(0); IIOImage iIOImage = new IIOImage(bufferedImage, null, null); //and write it imageWriter.write(null, iIOImage, imageWriteParam); Unfortunately, the files that I receive are often very large and the BufferedImage cannot be created. I have been trying to find a way to stream from the ImageReader directly to the ImageWriter but I cannot find out how to do that. Anybody with a suggestion?

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• latin1/unicode conversion problem with ajax request and special characters

  - by mfn

  Server is PHP5 and HTML charset is latin1 (iso-8859-1). With regular form POST requests, there's no problem with "special" characters like the em dash (–) for example. Although I don't know for sure, it works. Probably because there exists a representable character for the browser at char code 150 (which is what I see in PHP on the server for a literal em dash with ord). Now our application also provides some kind of preview mechanism via ajax: the text is sent to the server and a complete HTML for a preview is sent back. However, the ordinary char code 150 em dash character when sent via ajax (tested with GET and POST) mutates into something more: %E2%80%93. I see this already in the apache log. According to various sources I found, e.g. http://www.tachyonsoft.com/uc0020.htm , this is the UTF8 byte representation of em dash and my current knowledge is that JavaScript handles everything in Unicode. However within my app, I need everything in latin1. Simply said: just like a regular POST request would have given me that em dash as char code 150, I would need that for the translated UTF8 representation too. That's were I'm failing, because with PHP on the server when I try to decode it with either utf8_decode(...) or iconv('UTF-8', 'iso-8859-1', ...) but in both cases I get a regular ? representing this character (and iconv also throws me a notice: Detected an illegal character in input string ). My goal is to find an automated solution, but maybe I'm trying to be überclever in this case? I've found other people simply doing manual replacing with a predefined input/output set; but that would always give me the feeling I could loose characters. The observant reader will note that I'm behind on understanding the full impact/complexity with things about Unicode and conversion of chars and I definitely prefer to understand the thing as a whole then a simply manual mapping. thanks

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