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  • asynchronous sockets

    - by user158182
    i need to receive an acknowledgement from server when receives a data for confirming that data has received the server and how to use GetSocketOption() in asynchronous method

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  • How to create a persistent connection using AS3 Sockets for a chat client

    - by Vivek
    I want to create a chat client in flash/flex for a chat server,something like a MUD/MOO client but I'm unable to create a persistent connection . I've been using the AS3 Socket class,but I'm getting disconnected from the server side,soon after the connection is made but the client still shows the 'connected' property as true .The server is asynchronous and was written in python using asyncore/asynchat, it works fine with most open source MOO/MUD clients . I tried connecting my program to a simple synchronous echo server,here both read and write worked fine with no disconnections from either side . So my question is how do I make a persistent connection with the server?

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  • Ruby Thread with "watchdog"

    - by Sergio Campamá
    I'm implementing a ruby server for handling sockets being created from GPRS modules. The thing is that when the module powers down, there's no indication that the socket closed. I'm doing threads to handle multiple sockets with the same server. What I'm asking is this: Is there a way to use a timer inside a thread, reset it after every socket input, and that if it hits the timeout, closes the thread? Where can I find more information about this? EDIT: Code example that doesn't detect the socket closing require 'socket' server = TCPServer.open(41000) loop do Thread.start(server.accept) do |client| puts "Client connected" begin loop do line = client.readline open('log.txt', 'a') { |f| f.puts line.strip } end rescue puts "Client disconnected" end end end

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  • C# Proxy, what is the best way to do this?

    - by Kin
    I'm writing a proxy using .NET and C#. It has a couple of functions that it needs to fulfill. I haven't done much Socket programming, and I am not sure the best way to go about it. Should I use Synchronous Sockets, Asynchronous sockets? Please help! It must... Accept Connections from the client on two different ports, and be able to receive data on both ports at the same time. When a connection is made on a port, it must immediately connect to the server, and start sending data as it receives it from the client to the server. Packets must be forwarded in the order they are received, exactly as they were received. It needs to be as low latency as possible. I don't need the ability for multiple clients to use the proxy, but it would be a nice feature if its easy to implement.

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  • socket programming: How do I handle out of band data

    - by soulmerge
    I just looked into wikipedia's entry on out-of-band data and as far as I understand, OOB data is somehow flagged more important and treated as ordinary data, but transmitted in a seperate stream, which profoundly confuses me. The actual question would be (besides "Could someone explain what OOB data is?"): I'm writing a unix application that uses sockets and need to make use of select() and was wondering what to do with the exceptfds parameter? Do I need to put all my sockets into this parameter and react to such events? Or do I just ignore them?

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  • Abnormally disconnected TCP sockets and write timeout

    - by James
    Hello I will try to explain the problem in shortest possible words. I am using c++ builder 2010. I am using TIdTCPServer and sending voice packets to a list of connected clients. Everything works ok untill any client is disconnected abnormally, For example power failure etc. I can reproduce similar disconnect by cutting the ethernet connection of a connected client. So now we have a disconnected socket but as you know it is not yet detected at server side so server will continue to try to send data to that client too. But when server try to write data to that disconnected client ...... Write() or WriteLn() HANGS there in trying to write, It is like it is wating for somekind of Write timeout. This hangs the hole packet distribution process as a result creating a lag in data transmission to all other clients. After few seconds "Socket Connection Closed" Exception is raised and data flow continues. Here is the code try { EnterCriticalSection(&SlotListenersCriticalSection); for(int i=0;i<SlotListeners->Count;i++) { try { //Here the process will HANG for several seconds on a disconnected socket ((TIdContext*) SlotListeners->Objects[i])->Connection->IOHandler->WriteLn("Some DATA"); }catch(Exception &e) { SlotListeners->Delete(i); } } }__finally { LeaveCriticalSection(&SlotListenersCriticalSection); } Ok i already have a keep alive mechanism which disconnect the socket after n seconds of inactivity. But as you can imagine, still this mechnism cant sync exactly with this braodcasting loop because this braodcasting loop is running almost all the time. So is there any Write timeouts i can specify may be through iohandler or something ? I have seen many many threads about "Detecting disconnected tcp socket" but my problem is little different, i need to avoid that hangup for few seconds during the write attempt. So is there any solution ? Or should i consider using some different mechanism for such data broadcasting for example the broadcasting loop put the data packet in some kind of FIFO buffer and client threads continuously check for available data and pick and deliver it to themselves ? This way if one thread hangs it will not stop/delay the over all distribution thread. Any ideas please ? Thanks for your time and help. Regards Jams

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  • Sockets and multithreading

    - by V0idExp
    Hi to all! I have an interesting (to me) problem... There are two threads, one for capturing data from std input and sending it through socket to server, and another one which receives data from blocking socket. So, when there's no reply from server, recv() call waits indefenitely, right? But instead of blocking only its calling thread, it blocks the overall process! Why this thing occurs?

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  • Swing code in sockets

    - by asb
    I am learning swings for making GUI. I was thinking which is the best possible way in case of socket with swings. 1. The whole swing code goes in the server file. All the handlers and logic in on server side. Client only create socket. 2. The server have logic part. The code for the swing to display interface goes on client side. Client Creates stream to send / rec. data from server. Whch is the good way out of 2 ?

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  • Increase the TCP receive window for a specific socket

    - by rursw1
    Hi, How to increase the TCP receive window for a specific socket? - I know how to do so for all the sockets by setting the registry key TcpWindowSize, but how do do that for a specific one? According to MSFT's documents, the way is Calling the Windows Sockets function setsockopt, which sets the receive window on a per-socket basis. But in setsockopt, it is mentioned about SO_RCVBUF : Specifies the total per-socket buffer space reserved for receives. This is unrelated to SO_MAX_MSG_SIZE and does not necessarily correspond to the size of the TCP receive window. So is it possible? How? Thanks.

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  • Is select() Ok to implement single socket read/write timeout ?

    - by chmike
    I have an application processing network communication with blocking calls. Each thread manages a single connection. I've added a timeout on the read and write operation by using select prior to read or write on the socket. Select is known to be inefficient when dealing with large number of sockets. But is it ok, in term of performance to use it with a single socket or are there more efficient methods to add timeout support on single sockets calls ? The benefit of select is to be portable.

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  • Is select() Ok to implemnet single socket read/write timeout ?

    - by chmike
    I have an application processing network communication with blocking calls. Each thread manages a single connection. I've added a timeout on the read and write operation by using select prior to read or write on the socket. Select is known to be inefficient when dealing with large number of sockets. But is it ok, in term of performance to use it with a single socket or are there more efficient methods to add timeout support on single sockets calls ? The benefit of select is to be portable.

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  • FTP .NET Sockets

    - by Jojo
    Hi Everyone, I have an FTP auto downloader program. It downloads new files from a given FTP folder. The application was successful for some FTP folders that i have tested. These folders contain 30 - 50 files. However, when i tried an FTP folder with 150 and 18000 files, i receive this error message: An established connection was aborted by the software in your host machine. My first assumptions will be because of firewalls or anti virus. I don't have administrative access to this computer so I would like to ask if there are other reasons for this before i raise this to our systems dept? Need anyone's help asap. Thanks :)

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  • Working with sockets in MFC

    - by fanq
    I'm trying to make a MFC application(client) that connects to a server on ("localhost",port 1234), the server replies to the client and the client reads from the server's response. The server is able to receive the data from the client and it sends the reply back to the socket from where it received it, but I am unable to read the reply from within the client. I am making a CAsyncSocket to connect to the server and send data and a CAsyncSocket with overloaded methods onAccet and onReceive to read the reply from the server. Please tell me what I'm doing wrong.

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  • Using LINQ, need help splitting a byte array on data received from Silverlight sockets

    - by gcadmes
    The message packats received contains multiple messages deliniated by a header=0xFD and a footer=0xFE // sample message packet with three // different size messages List<byte> receiveBuffer = new List<byte>(); receiveBuffer.AddRange(new byte[] { 0xFD, 1, 2, 0xFE, 0xFD, 1, 2, 3, 4, 5, 6, 7, 8, 0xFE, 0xFD, 33, 65, 25, 44, 0xFE}); // note: this sample code is without synchronization, // statements, error handling...etc. while (receiveBuffer.Count > 0) { var bytesInRange = receiveBuffer.TakeWhile(n => n != 0xFE); foreach (var n in bytesInRange) Console.WriteLine(n); // process message.. // 1) remove bytes read from receive buffer // 2) construct message object... // 3) etc... receiveBuffer.RemoveRange(0, bytesInRange.Count()); } As you can see, (including header/footer) the first message in this message packet contains 4 bytes, and the 2nd message contains 10 bytes,a and the 3rd message contains 6 bytes. In the while loop, I was expecting the TakeWhile to add the bytes that did not equal the footer part of the message. Note: Since I am removing the bytes after reading them, the header can always be expected to be at position '0'. I searched examples for splitting byte arrays, but non demonstrated splitting on arrays of unknown and fluctuating sizes. Any help will be greatly appreciated. thanks much!

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  • Problem with sockets in C#

    - by depo
    Socket socket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp); ... socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, 1000); ... socket.Send(bytesSent, bytesSent.Length, 0); ... bytes = socket.Receive(bytesReceived, bytesReceived.Length, 0); After socket has sent the data, server does not respond so that program waits for response. How to stop receiving data after 1000 miliseconds? ?

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  • Bandwidth Limit User

    - by user45611
    Hello, i'm saxtor i would like to know how to limit users bandwidth for 10gb per day however i dont want to limit them by ipaddress because if they where to go to an internet cafe the users at the cafe will be restricted with that quota, i need to log them via sockets, example the user request to download a file from http://localhost with there username and password, when they download the file sql will update there bandwidth they used, i have a script here but its not working my buffer doesnt work that rate when a user uses multiple connections thanks for the help!. /** * @author saxtor if you can improve this code email me @saxtorinc.com * @copyright 2010 / /* * CREATE TABLE IF NOT EXISTS max_traffic ( id int(255) NOT NULL AUTO_INCREMENT, limit int(255) NOT NULL, PRIMARY KEY (id) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=0 ; */ //SQL Connection [this is hackable for testing] date_default_timezone_set("America/Guyana"); mysql_connect("localhost", "root", "") or die(mysql_error()); mysql_select_db("Quota") or die(mysql_error()); function quota($id) { $result = mysql_query("SELECT `limit` FROM max_traffic WHERE id='$id' ") or die(error_log(mysql_error()));; $row = mysql_fetch_array($result); return $row[0]; } function update_quota($id,$value) { $result = mysql_query("UPDATE `max_traffic` SET `limit`='$value' WHERE id='$id'") or die(mysql_error()); return $value; } if ( quota(1) != 0) $limit = quota(1); else $limit = 0; $multipart = false; //was a part of the file requested? (partial download) $range = $_SERVER["HTTP_RANGE"]; if ($range) { //pass client Range header to rapidshare // _insert($range); $cookie .= "\r\nRange: $range"; $multipart = true; header("X-UR-RANGE-Range: $range"); } $url = 'http://127.0.0.1/puppy.iso'; $filename = basename($url); //octet-stream + attachment = client always stores file header('Content-type: application/octet-stream'); header('Content-Disposition: attachment; filename="'.$filename.'"'); //always included so clients know this script supports resuming header("Accept-Ranges: bytes"); //awful hack to pass rapidshare the premium cookie $user_agent = ini_get("user_agent"); ini_set("user_agent", $user_agent . "\r\nCookie: enc=$cookie"); $httphandle = fopen($url, "r"); $headers = stream_get_meta_data($httphandle); $size = $headers["wrapper_data"][6]; $sizer = explode(' ',$size); $size = $sizer[1]; //let's check the return header of rapidshare for range / length indicators //we'll just pass these to the client foreach ($headers["wrapper_data"] as $header) { $header = trim($header); if (substr(strtolower($header), 0, strlen("content-range")) == "content-range") { // _insert($range); header($header); header("X-RS-RANGE-" . $header); $multipart = true; //content-range indicates partial download } elseif (substr(strtolower($header), 0, strlen("Content-Length")) == "content-length") { // _insert($range); header($header); header("X-RS-CL-" . $header); } } if ($multipart) header('HTTP/1.1 206 Partial Content'); flush(); $speed = 4128; $packet = 1; //this is private dont touch. $bufsize = 128; //this is private dont touch/ $bandwidth = 0; //this is private dont touch. while (!(connection_aborted() || connection_status() == 1) && $size > 0) { while (!feof($httphandle) && $size > 0) { if ($limit <= 0 ) $size = 0; if ( $size < $bufsize && $size != 0 && $limit != 0) { echo fread($httphandle,$size); $bandwidth += $size; } else { if( $limit != 0) echo fread($httphandle,$bufsize); $bandwidth += $bufsize; } $size -= $bufsize; $limit -= $bufsize; flush(); if ($speed > 0 && ($bandwidth > $speed*$packet*103)) { usleep(100000); $packet++; //update_quota(1,$limit); } error_log(update_quota(1,$limit)); $limit = quota(1); //if( $size <= 0 ) // exit; } fclose($httphandle); } exit; ?

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  • Binary stream 'NN' does not contain a valid BinaryHeader. Possible causes are invalid stream or obje

    - by FinancialRadDeveloper
    I am passing user defined classes over sockets. The SendObject code is below. It works on my local machine, but when I publish to the WebServer which is then communicating with the App Server on my own machine it fails. public bool SendObject(Object obj, ref string sErrMsg) { try { MemoryStream ms = new MemoryStream(); BinaryFormatter bf1 = new BinaryFormatter(); bf1.Serialize(ms, obj); byte[] byArr = ms.ToArray(); int len = byArr.Length; m_socClient.Send(byArr); return true; } catch (Exception e) { sErrMsg = "SendObject Error: " + e.Message; return false; } } I can do this fine if it is one class in my tools project and the other class about UserData just doesn't want to know. Frustrating! Ohh. I think its because the UserData class has a DataSet inside it. Funnily enough I have seen this work, but then after 1 request it goes loopy and I can't get it to work again. Anyone know why this might be? I have looked at comparing the dlls to make sure they are the same on the WebServer and on my local machine and they look to be so as I have turned on versioning in the AssemblyInfo.cs to double check. Edit: Ok it seems that the problem is with size. If I keep it under 1024 byes ( I am guessing here) it works on the web server and doesnt if it has a DataSet inside it.k In fact this is so puzzling I converted the DataSet to a string using ds.GetXml() and this also causes it to blow up. :( So it seems that across the network something with my sockets is wrong and doesn't want to read in the data. JonSkeet where are you. ha ha. I would offer Rep but I don't have any. Grr

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  • Why is it assumed that send may return with less than requested data transmitted on a blocking socke

    - by Ernelli
    The standard method to send data on a stream socket has always been to call send with a chunk of data to write, check the return value to see if all data was sent and then keep calling send again until the whole message has been accepted. For example this is a simple example of a common scheme: int send_all(int sock, unsigned char *buffer, int len) { int nsent; while(len 0) { nsent = send(sock, buffer, len, 0); if(nsent == -1) // error return -1; buffer += nsent; len -= nsent; } return 0; // ok, all data sent } Even the BSD manpage mentions that ...If no messages space is available at the socket to hold the message to be transmitted, then send() normally blocks... Which indicates that we should assume that send may return without sending all data. Now I find this rather broken but even W. Richard Stevens assumes this in his standard reference book about network programming, not in the beginning chapters, but the more advanced examples uses his own writen (write all data) function instead of calling write. Now I consider this still to be more or less broken, since if send is not able to transmit all data or accept the data in the underlying buffer and the socket is blocking, then send should block and return when the whole send request has been accepted. I mean, in the code example above, what will happen if send returns with less data sent is that it will be called right again with a new request. What has changed since last call? At max a few hundred CPU cycles have passed so the buffer is still full. If send now accepts the data why could'nt it accept it before? Otherwise we will end upp with an inefficient loop where we are trying to send data on a socket that cannot accept data and keep trying, or else? So it seems like the workaround, if needed, results in heavily inefficient code and in those circumstances blocking sockets should be avoided at all an non blocking sockets together with select should be used instead.

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  • Qt Socket blocking functions required to run in QThread where created. Any way past this?

    - by Alexander Kondratskiy
    The title is very cryptic, so here goes! I am writing a client that behaves in a very synchronous manner. Due to the design of the protocol and the server, everything has to happen sequentially (send request, wait for reply, service reply etc.), so I am using blocking sockets. Here is where Qt comes in. In my application I have a GUI thread, a command processing thread and a scripting engine thread. I create the QTcpSocket in the command processing thread, as part of my Client class. The Client class has various methods that boil down to writing to the socket, reading back a specific number of bytes, and returning a result. The problem comes when I try to directly call Client methods from the scripting engine thread. The Qt sockets randomly time out and when using a debug build of Qt, I get these warnings: QSocketNotifier: socket notifiers cannot be enabled from another thread QSocketNotifier: socket notifiers cannot be disabled from another thread Anytime I call these methods from the command processing thread (where Client was created), I do not get these problems. To simply phrase the situation: Calling blocking functions of QAbstractSocket, like waitForReadyRead(), from a thread other than the one where the socket was created (dynamically allocated), causes random behaviour and debug asserts/warnings. Anyone else experienced this? Ways around it? Thanks in advance.

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  • How to host WCF service and TCP server on same socket?

    - by Ole Jak
    Tooday I use ServiceHost for self hosting WCF cervices. I want to host near to my WCF services my own TCP programm for direct sockets operations (like lien to some sort of broadcasting TCP stream) I need control over namespaces (so I would be able to let my clients to send TCP streams directly into my service using some nice URLs like example.com:port/myserver/stream?id=1 or example.com:port/myserver/stream?id=anything and so that I will not be bothered with Idea of 1 client for 1 socket at one time moment, I realy want to keep my WCF services on the same port as my own server or what it is so to be able to call www.example.com:port/myWCF/stream?id=222...) Can any body please help me with this? I am using just WCF now. And I do not enjoy how it works. That is one of many resons why I want to start migration to clear TCP=) I can not use net-tcp binding or any sort of other cool WS-* binding (tooday I use the simpliest one so that my clients like Flash, AJAX, etc connect to me with ease). I needed Fast and easy in implemrnting connection protocol like one I created fore use with Sockets for real time hi ammount of data transfering. So.. Any Ideas? Please - I need help.

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  • Best way to do interprocess communication on Mac OS X

    - by jbrennan
    I'm looking at building a Cocoa application on the Mac with a back-end daemon process (really just a mostly-headless Cocoa app, probably), along with 0 or more "client" applications running locally (although if possible I'd like to support remote clients as well; the remote clients would only ever be other Macs or iPhone OS devices). The data being communicated will be fairly trivial, mostly just text and commands (which I guess can be represented as text anyway), and maybe the occasional small file (an image possibly). I've looked at a few methods for doing this but I'm not sure which is "best" for the task at hand. Things I've considered: Reading and writing to a file (…yes), very basic but not very scalable. Pure sockets (I have no experience with sockets but I seem to think I can use them to send data locally and over a network. Though it seems cumbersome if doing everything in Cocoa Distributed Objects: seems rather inelegant for a task like this NSConnection: I can't really figure out what this class even does, but I've read of it in some IPC search results I'm sure there are things I'm missing, but I was surprised to find a lack of resources on this topic.

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  • Winsock tcp/ip Socket listening but connection refused, race condition?

    - by Wayne
    Hello folks. This involves two automated unit tests which each start up a tcp/ip server that creates a non-blocking socket then bind()s and listen()s in a loop on select() for a client that connects and downloads some data. The catch is that they work perfectly when run separately but when run as a test suite, the second test client will fail to connect with WSACONNREFUSED... UNLESS there is a Thread.Sleep() of several seconds between them??!!! Interestingly, there is retry loop every 1 second for connecting after any failure. So the second test loops for a while until timeout after 10 minutes. During that time, netstat -na shows the correct port number is in the LISTEN state for the server socket. So if it is in the listen state? Why won't it accept the connection? In the code, there are log messages that show the select NEVER even gets a socket ready to read (which means ready to accept a connection when it applies to a listening socket). Obviously the problem must be related to some race condition between finishing one test which means close() and shutdown() on each end of the socket, and the start up of the next. This wouldn't be so bad if the retry logic allowed it to connect eventually after a couple of seconds. However it seems to get "gummed up" and won't even retry. However, for some strange reason the listening socket SAYS it's in the LISTEN state even through keeps refusing connections. So that means it's the Windoze O/S which is actually catching the SYN packet and returning a RST packet (which means "Connection Refused"). The only other time I ever saw this error was when the code had a problem that caused hundreds of sockets to get stuck in TIME_WAIT state. But that's not the case here. netstat shows only about a dozen sockets with only 1 or 2 in TIME_WAIT at any given moment. Please help.

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