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  • Packet fragmentation when sending data via SSLStream

    - by Ive
    When using an SSLStream to send a 'large' chunk of data (1 meg) to a (already authenticated) client, the packet fragmentation / dissasembly I'm seeing is FAR greater than when using a normal NetworkStream. Using an async read on the client (i.e. BeginRead()), the ReadCallback is repeatedly called with exactly the same size chunk of data up until the final packet (the remainder of the data). With the data I'm sending (it's a zip file), the segments happen to be 16363 bytes long. Note: My receive buffer is much bigger than this and changing it's size has no effect I understand that SSL encrypts data in chunks no bigger than 18Kb, but since SSL sits on top of TCP, I wouldn't think that the number of SSL chunks would have any relevance to the TCP packet fragmentation? Essentially, the data is taking about 20 times longer to be fully read by the client than with a standard NetworkStream (both on localhost!) What am I missing? EDIT: I'm beginning to suspect that the receive (or send) buffer size of an SSLStream is limited. Even if I use synchronous reads (i.e. SSLStream.Read()), no more data ever becomes available, regardless of how long I wait before attempting to read. This would be the same behavior as if I were to limit the receive buffer to 16363 bytes. Setting the Underlying NetworkStream's SendBufferSize (on the server), and ReceiveBufferSize (on the client) has no effect.

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  • Listening for TCP and UDP requests on the same port

    - by user339328
    I am writing a Client/Server set of programs Depending on the operation requested by the client, I use make TCP or UDP request. Implementing the client side is straight-forward, since I can easily open connection with any protocol and send the request to the server-side. On the servers-side, on the other hand, I would like to listen both for UDP and TCP connections on the same port. Moreover, I like the the server to open new thread for each connection request. I have adopted the approach explained in: link text I have extended this code sample by creating new threads for each TCP/UDP request. This works correctly if I use TCP only, but it fails when I attempt to make UDP bindings. Please give me any suggestion how can I correct this. tnx Here is the Server Code: public class Server { public static void main(String args[]) { try { int port = 4444; if (args.length > 0) port = Integer.parseInt(args[0]); SocketAddress localport = new InetSocketAddress(port); // Create and bind a tcp channel to listen for connections on. ServerSocketChannel tcpserver = ServerSocketChannel.open(); tcpserver.socket().bind(localport); // Also create and bind a DatagramChannel to listen on. DatagramChannel udpserver = DatagramChannel.open(); udpserver.socket().bind(localport); // Specify non-blocking mode for both channels, since our // Selector object will be doing the blocking for us. tcpserver.configureBlocking(false); udpserver.configureBlocking(false); // The Selector object is what allows us to block while waiting // for activity on either of the two channels. Selector selector = Selector.open(); tcpserver.register(selector, SelectionKey.OP_ACCEPT); udpserver.register(selector, SelectionKey.OP_READ); System.out.println("Server Sterted on port: " + port + "!"); //Load Map Utils.LoadMap("mapa"); System.out.println("Server map ... LOADED!"); // Now loop forever, processing client connections while(true) { try { selector.select(); Set<SelectionKey> keys = selector.selectedKeys(); // Iterate through the Set of keys. for (Iterator<SelectionKey> i = keys.iterator(); i.hasNext();) { SelectionKey key = i.next(); i.remove(); Channel c = key.channel(); if (key.isAcceptable() && c == tcpserver) { new TCPThread(tcpserver.accept().socket()).start(); } else if (key.isReadable() && c == udpserver) { new UDPThread(udpserver.socket()).start(); } } } catch (Exception e) { e.printStackTrace(); } } } catch (Exception e) { e.printStackTrace(); System.err.println(e); System.exit(1); } } } The UDPThread code: public class UDPThread extends Thread { private DatagramSocket socket = null; public UDPThread(DatagramSocket socket) { super("UDPThread"); this.socket = socket; } @Override public void run() { byte[] buffer = new byte[2048]; try { DatagramPacket packet = new DatagramPacket(buffer, buffer.length); socket.receive(packet); String inputLine = new String(buffer); String outputLine = Utils.processCommand(inputLine.trim()); DatagramPacket reply = new DatagramPacket(outputLine.getBytes(), outputLine.getBytes().length, packet.getAddress(), packet.getPort()); socket.send(reply); } catch (IOException e) { e.printStackTrace(); } socket.close(); } } I receive: Exception in thread "UDPThread" java.nio.channels.IllegalBlockingModeException at sun.nio.ch.DatagramSocketAdaptor.receive(Unknown Source) at server.UDPThread.run(UDPThread.java:25) 10x

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  • Can I make TCP/IP session to run less than 60 seconds?

    - by Pavel
    Our server is overloaded with TCP/IP sessions, we have 1200 - 1500 of them. Most of them are hanging in TIME_OUT state. It turns out that a connection in TIME_OUT state occupies a socket until 60 second time-out is elapsed. The problem is that the server gets unresponsive and many clients are not getting served. I have made a simple test: download an XML file from the server with Internet Explorer 8.0 The download finishes in a fraction of second. But then I see that the TCP/IP connection is hanging in TIME_OUT state for 60 seconds. Is there any way to get rid of TIME_OUT waiting or make it less to free the socket for new connections? I understand why TCP/IP connection enters TIME_OUT state, but I don't understand why Internet Explorer does not close the connection after the XML file download is over. The details. Our server runs web service written in Perl (mod-perl). The service provides weather data to clients. Client is a Flash appication (actually Flash ActiveX control embedded in Windows application). Apache "Keep Alive" option is set to 0

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  • Polling servers at the same port - Threads and Java

    - by John
    Hi there. I'm currently busy working on an IP ban tool for the early versions of Call of Duty 1. (Apparently such a feature wasn't implemented in these versions). I've finished a single threaded application but it won't perform well enough for multiple servers, which is why I am trying to implement threading. Right now, each server has its own thread. I have a Networking class, which has a method; "GetStatus" -- this method is synchronized. This method uses a DatagramSocket to communicate with the server. Since this method is static and synchronized, I shouldn't get in trouble and receive a whole bunch of "Address already in use" exceptions. However, I have a second method named "SendMessage". This method is supposed to send a message to the server. How can I make sure "SendMessage" cannot be invoked when there's already a thread running in "GetStatus", and the other way around? If I make both synchronized, I will still get in trouble if Thread A is opening a socket on Port 99999 and invoking "SendMessage" while Thread B is opening a socket on the same port and invoking "GetStatus"? (Game servers are usually hosted on the same ports) I guess what I am really after is a way to make an entire class synchronized, so that only one method can be invoked and run at a time by a single thread. Hope that what I am trying to accomplish/avoid is made clear in this text. Any help is greatly appreciated.

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  • How do I send telnet option codes?

    - by Matt
    I've written a socket listener in Java that just sends some data to the client. If I connect to the server using telnet, I want the server to send some telnet option codes. Do I just send these like normal messages? Like, if I wanted the client to print "hello", I would do this: PrintWriter out = new PrintWriter(clientSocket.getOutputStream()); out.print("hello"); out.flush(); But when I try to send option codes, the client just prints them. Eg, the IAC char (0xff) just gets printed as a strange y character when I do this: PrintWriter out = new PrintWriter(clientSocket.getOutputStream()); out.print((char)0xff); out.flush();

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  • GUI Agent accepts statuses from Daemon and shows it using progress indicator

    - by Pavel
    Hi to all! My application is a GUI agent, which communicate with daemon through the unix domain socket, wrapped in CFSocket.... So there are main loop and added CFRunLoop source. Daemon sends statuses and agent shows it with a progress indicator. When there are any data on socket, callback function begin to work and at this time I have to immediately show the new window with progress indicator and increase counter. //this function initiate the runloop for listening socket - (int) AcceptDaemonConnection:(ConnectionRef)conn { int err = 0; conn->fSockCF = CFSocketCreateWithNative(NULL, (CFSocketNativeHandle) conn->fSockFD, kCFSocketAcceptCallBack, ConnectionGotData, NULL); if (conn->fSockCF == NULL) err = EINVAL; if (err == 0) { conn->fRunLoopSource = CFSocketCreateRunLoopSource(NULL, conn->fSockCF, 0); if (conn->fRunLoopSource == NULL) err = EINVAL; else CFRunLoopAddSource(CFRunLoopGetCurrent(), conn->fRunLoopSource, kCFRunLoopDefaultMode); CFRelease(conn->fRunLoopSource); } return err; } // callback function void ConnectionGotData(CFSocketRef s, CFSocketCallBackType type, CFDataRef address, const void * data, void * info) { #pragma unused(s) #pragma unused(address) #pragma unused(info) assert(type == kCFSocketAcceptCallBack); assert( (int *) data != NULL ); assert( (*(int *) data) != -1 ); TStatusUpdate status; int nativeSocket = *(int *) data; status = [agg AcceptPacket:nativeSocket]; // [stWindow InitNewWindow] inside [agg SendUpdateStatus:status.percent]; } AcceptPacket function receives packet from the socket and trying to show new window with progress indicator. Corresponding function is called, but nothing happens... I think, that I have to make work the main application loop with interrupting CFSocket loop... Or send a notification? No idea....

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  • Communicate between separate MPI-Programs

    - by Fyg
    I have the following problem: Program 1 has a huge amount of data, say 10GB. The data in question consists of large integer- and double-arrays. Program 2 has 1..n MPI processes that use tiles of this data to compute results. How can I send the data from program 1 to the MPI Processes? Using File I/O is out of question. The compute node has sufficient RAM.

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  • buffer size for socket connection in c++

    - by wyatt
    I'm trying to build a basic POP3 mail client in C/++, but I've run into a bit of an issue. Since you have to define the buffer size when building the program, but a message can be arbitrarily large, how do you, say, get the mail server to send it to you in parts? And if this isn't the correct means of solving the problem, what is? And while I'm here, can anyone confirm for me that RFC 2822 is still the current document defining email layout? Thanks

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  • How to "unbind" a socket programmatically?

    - by ryan1894
    1) The socket doesn't seem to unbind from the LocalEndPoint until the process ends. 2) I have tried the solutions from the other question, and also tried waiting a minute - to no avail. 3) At the moment I have tried the below to get rid of the socket and its connections: public static void killUser(User victim) { LingerOption lo = new LingerOption(false, 0); victim.connectedSocket.SetSocketOption(SocketOptionLevel.Socket,SocketOptionName.Linger, lo); victim.connectedSocket.Shutdown(SocketShutdown.Both); victim.connectedSocket.Disconnect(true); victim.connectedSocket.Close(); clients.RemoveAt(victim.ID); } 4) After a bit of googling, I can't seem to be able to unbind a port, thus if I have a sufficient amount of connecting clients, I will eventually run out of ports to listen on.

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  • "Can´t open socket or connection refused" with .NET

    - by HoNgOuRu
    Im getting a connection refused when I try to send some data to my server app using netcat. server side: IPAddress ip; ip = Dns.GetHostEntry("localhost").AddressList[0]; IPEndPoint ipFinal = new IPEndPoint(ip, 12345); Socket socket = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp); socket.Bind(ipFinal); socket.Listen(100); Socket handler = socket.Accept(); ------> it stops here......nothing happens

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  • Java Socks Proxy Socket Error

    - by Ionut Ungureanu
    I am trying to create a http request through a SOCKS (v4 / v5) proxy in Java. After reading about socks communication protocol on WikiPedia, I have put togheter this piece of code: Socket sock = new Socket(); InetSocketAddress remoteProxyAddress = new InetSocketAddress(proxy ip, proxy port); sock.connect(remoteProxyAddress, connTimeout); InputStream in = sock.getInputStream(); OutputStream out = sock.getOutputStream(); out.write(0x04); out.write(0x01); out.write((endpoint.getPort() >> 8) & 0xff); out.write((endpoint.getPort() >> 0) & 0xff); out.write(endpoint.getAddress().getAddress()); out.write(0x0); out.flush(); And here comes the part where I read from the proxy server. The problem is that the response is always "-1". I have tried the proxy on Firefox and it works perfect. So... the problem is in my app. Can anyone help me? Thanks!

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  • Can I avoid a threaded UDP socket in Python dropping data?

    - by 666craig
    First off, I'm new to Python and learning on the job, so be gentle! I'm trying to write a threaded Python app for Windows that reads data from a UDP socket (thread-1), writes it to file (thread-2), and displays the live data (thread-3) to a widget (gtk.Image using a gtk.gdk.pixbuf). I'm using queues for communicating data between threads. My problem is that if I start only threads 1 and 3 (so skip the file writing for now), it seems that I lose some data after the first few samples. After this drop it looks fine. Even by letting thread 1 complete before running thread 3, this apparent drop is still there. Apologies for the length of code snippet (I've removed the thread that writes to file), but I felt removing code would just prompt questions. Hope someone can shed some light :-) import socket import threading import Queue import numpy import gtk gtk.gdk.threads_init() import gtk.glade import pygtk class readFromUDPSocket(threading.Thread): def __init__(self, socketUDP, readDataQueue, packetSize, numScans): threading.Thread.__init__(self) self.socketUDP = socketUDP self.readDataQueue = readDataQueue self.packetSize = packetSize self.numScans = numScans def run(self): for scan in range(1, self.numScans + 1): buffer = self.socketUDP.recv(self.packetSize) self.readDataQueue.put(buffer) self.socketUDP.close() print 'myServer finished!' class displayWithGTK(threading.Thread): def __init__(self, displayDataQueue, image, viewArea): threading.Thread.__init__(self) self.displayDataQueue = displayDataQueue self.image = image self.viewWidth = viewArea[0] self.viewHeight = viewArea[1] self.displayData = numpy.zeros((self.viewHeight, self.viewWidth, 3), dtype=numpy.uint16) def run(self): scan = 0 try: while True: if not scan % self.viewWidth: scan = 0 buffer = self.displayDataQueue.get(timeout=0.1) self.displayData[:, scan, 0] = numpy.fromstring(buffer, dtype=numpy.uint16) self.displayData[:, scan, 1] = numpy.fromstring(buffer, dtype=numpy.uint16) self.displayData[:, scan, 2] = numpy.fromstring(buffer, dtype=numpy.uint16) gtk.gdk.threads_enter() self.myPixbuf = gtk.gdk.pixbuf_new_from_data(self.displayData.tostring(), gtk.gdk.COLORSPACE_RGB, False, 8, self.viewWidth, self.viewHeight, self.viewWidth * 3) self.image.set_from_pixbuf(self.myPixbuf) self.image.show() gtk.gdk.threads_leave() scan += 1 except Queue.Empty: print 'myDisplay finished!' pass def quitGUI(obj): print 'Currently active threads: %s' % threading.enumerate() gtk.main_quit() if __name__ == '__main__': # Create socket (IPv4 protocol, datagram (UDP)) and bind to address socketUDP = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) host = '192.168.1.5' port = 1024 socketUDP.bind((host, port)) # Data parameters samplesPerScan = 256 packetsPerSecond = 1200 packetSize = 512 duration = 1 # For now, set a fixed duration to log data numScans = int(packetsPerSecond * duration) # Create array to store data data = numpy.zeros((samplesPerScan, numScans), dtype=numpy.uint16) # Create queue for displaying from readDataQueue = Queue.Queue(numScans) # Build GUI from Glade XML file builder = gtk.Builder() builder.add_from_file('GroundVue.glade') window = builder.get_object('mainwindow') window.connect('destroy', quitGUI) view = builder.get_object('viewport') image = gtk.Image() view.add(image) viewArea = (1200, samplesPerScan) # Instantiate & start threads myServer = readFromUDPSocket(socketUDP, readDataQueue, packetSize, numScans) myDisplay = displayWithGTK(readDataQueue, image, viewArea) myServer.start() myDisplay.start() gtk.gdk.threads_enter() gtk.main() gtk.gdk.threads_leave() print 'gtk.main finished!'

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  • java socket programming problem

    - by mk.persia
    Hi, what's wrong with my code? sorry about my bad English package sockettest; import java.io.*; import java.net.*; class sevr implements Runnable{ public void run() { ServerSocket sSkt = null; Socket skt = null; BufferedReader br = null; BufferedWriter bw = null; try{ System.out.println("Server: is about to create socket"); sSkt = new ServerSocket(6666); System.out.println("Server: socket created"); } catch(IOException e){ System.out.println("Server: socket creation failure"); } try{ System.out.println("Server: is listening"); skt = sSkt.accept(); System.out.println("Server: Connection Established"); } catch(IOException e){ System.out.println("Server: listening failed"); } try{ System.out.println("Server: creating streams"); br = new BufferedReader(new InputStreamReader(skt.getInputStream())); bw = new BufferedWriter(new OutputStreamWriter(skt.getOutputStream())); System.out.println("Server: stream done"); } catch(IOException e){ System.out.println("Server: stream failed"); } System.out.println("Server: reading the request"); try{ String line = null; while((line =br.readLine()) != null){ System.out.println("Server: client said- "+ line); } } catch(IOException e){ System.out.println("Server: reading failed"); } System.out.println("Server: reading fished"); System.out.println("Server: responding"); try{ bw.write("Hi! I am server!"); } catch(IOException e){ System.out.println("Server: responding failed"); } System.out.println("Server: responding finished"); System.out.println("Server: is finishing"); try { br.close(); bw.close(); skt.close(); sSkt.close(); } catch (IOException e) { System.out.println("Server: finishing failed"); } System.out.println("Server: done"); } } class clnt implements Runnable{ public void run() { Socket skt = null; BufferedReader br = null; BufferedWriter bw = null; try{ System.out.println("Client: about to create socket"); skt = new Socket(InetAddress.getLocalHost(),6666); System.out.println("Client: socket created"); } catch(IOException e){ System.out.println("Client: socket creation failure"); } try{ System.out.println("Client: creating streams"); br = new BufferedReader(new InputStreamReader(skt.getInputStream())); bw = new BufferedWriter(new OutputStreamWriter(skt.getOutputStream())); System.out.println("Client: stream done"); } catch(IOException e){ System.out.println("Client: stream failed"); } System.out.println("Client: requesting"); try{ bw.write("Hi! I am Client!"); } catch(IOException e){ System.out.println("Client: requesting failed"); } System.out.println("Client: requesting finished"); System.out.println("Client: reading the respond"); try{ String line = null; while((line =br.readLine()) != null){ System.out.println("Client: server said- "+ line); } } catch(IOException e){ System.out.println("Client: reading failed"); } System.out.println("Client: reading fished"); System.out.println("Clientrver: is finishing"); try { br.close(); bw.close(); skt.close(); } catch (IOException e) { System.out.println("Client: finishing failed"); } System.out.println("Client: done"); } } public class Main { public static void main(String[] args) { System.out.println("Main started"); Thread sThread = new Thread(new sevr()); Thread cThread = new Thread(new clnt()); sThread.start(); cThread.start(); try { sThread.join(); cThread.join(); } catch (InterruptedException ex) { System.out.println("joining failed"); } System.out.println("Main done"); } } output: Main started Server: is about to create socket Client: about to create socket Client: socket created Client: creating streams Server: socket created Server: is listening Server: Connection Established Server: creating streams Server: stream done Server: reading the request Client: stream done Client: requesting Client: requesting finished Client: reading the respond and it waits here forever!

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  • Writing Java code in Matlab?

    - by scooziexp
    Hi, I'm trying to use the Java commands pw.println() and br.readLine() in Matlab because I have set up a socket (input_socket2) between Matlab and a command-line program I want to control using Java classes BufferedReader and PrintWriter. Before the following snippet of code, I implemented another socket that goes between 2 computers. This works great and I also know that the following snippet of code successfully opens up a communication line between Matlab and the other program. However, Matlab throws an error at pw.println('noop'). I think it has something to do with syntax, but I'm not sure how to write the command in Matlab syntax then: try input_socket2 = Socket(host2,port2); input_stream2 = input_socket2.getInputStream; d_input_stream2 = DataInputStream(input_stream2); br = BufferedReader(InputStreamReader(input_stream2)); pw = PrintWriter(input_socket2.getOutputStream,true); pw.println('noop') br.read end Any ideas?

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  • Sending email to gmail account using c++ on windows error check

    - by LCD Fire
    I know this has been disscused a lot, but I I'm not asking how to do it, I'm just asking why it doesn't work. What I am doing wrong. It says that the email was sent succesfully but I don't see it in my inbox. I want to send an email to a gmail account, not through it. #include <iostream> #include <windows.h> #include <fstream> #include <conio.h> #pragma comment(lib, "ws2_32.lib") // Insist on at least Winsock v1.1 const int VERSION_MAJOR = 1; const int VERSION_MINOR = 1; #define CRLF "\r\n" // carriage-return/line feed pair using namespace std; // Basic error checking for send() and recv() functions void Check(int iStatus, char *szFunction) { if((iStatus != SOCKET_ERROR) && (iStatus)) return; cerr<< "Error during call to " << szFunction << ": " << iStatus << " - " << GetLastError() << endl; } int main(int argc, char *argv[]) { int iProtocolPort = 25; char szSmtpServerName[64] = ""; char szToAddr[64] = ""; char szFromAddr[64] = ""; char szBuffer[4096] = ""; char szLine[255] = ""; char szMsgLine[255] = ""; SOCKET hServer; WSADATA WSData; LPHOSTENT lpHostEntry; LPSERVENT lpServEntry; SOCKADDR_IN SockAddr; // Check for four command-line args //if(argc != 5) // ShowUsage(); // Load command-line args lstrcpy(szSmtpServerName, "smtp.gmail.com"); lstrcpy(szToAddr, "[email protected]"); lstrcpy(szFromAddr, "[email protected]"); // Create input stream for reading email message file ifstream MsgFile("D:\\d.txt"); // Attempt to intialize WinSock (1.1 or later) if(WSAStartup(MAKEWORD(VERSION_MAJOR, VERSION_MINOR), &WSData)) { cout << "Cannot find Winsock v" << VERSION_MAJOR << "." << VERSION_MINOR << " or later!" << endl; return 1; } // Lookup email server's IP address. lpHostEntry = gethostbyname(szSmtpServerName); if(!lpHostEntry) { cout << "Cannot find SMTP mail server " << szSmtpServerName << endl; return 1; } // Create a TCP/IP socket, no specific protocol hServer = socket(PF_INET, SOCK_STREAM, 0); if(hServer == INVALID_SOCKET) { cout << "Cannot open mail server socket" << endl; return 1; } // Get the mail service port lpServEntry = getservbyname("mail", 0); // Use the SMTP default port if no other port is specified if(!lpServEntry) iProtocolPort = htons(IPPORT_SMTP); else iProtocolPort = lpServEntry->s_port; // Setup a Socket Address structure SockAddr.sin_family = AF_INET; SockAddr.sin_port = iProtocolPort; SockAddr.sin_addr = *((LPIN_ADDR)*lpHostEntry->h_addr_list); // Connect the Socket if(connect(hServer, (PSOCKADDR) &SockAddr, sizeof(SockAddr))) { cout << "Error connecting to Server socket" << endl; return 1; } // Receive initial response from SMTP server Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() Reply"); // Send HELO server.com sprintf(szMsgLine, "HELO %s%s", szSmtpServerName, CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() HELO"); Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() HELO"); // Send MAIL FROM: <[email protected]> sprintf(szMsgLine, "MAIL FROM:<%s>%s", szFromAddr, CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() MAIL FROM"); Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() MAIL FROM"); // Send RCPT TO: <[email protected]> sprintf(szMsgLine, "RCPT TO:<%s>%s", szToAddr, CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() RCPT TO"); Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() RCPT TO"); // Send DATA sprintf(szMsgLine, "DATA%s", CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() DATA"); Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() DATA"); //strat writing about the subject, end it with two CRLF chars and after that you can //write data to the body oif the message sprintf(szMsgLine, "Subject: My own subject %s%s", CRLF, CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() DATA"); // Send all lines of message body (using supplied text file) MsgFile.getline(szLine, sizeof(szLine)); // Get first line do // for each line of message text... { sprintf(szMsgLine, "%s%s", szLine, CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() message-line"); MsgFile.getline(szLine, sizeof(szLine)); // get next line. } while(!MsgFile.eof()); // Send blank line and a period sprintf(szMsgLine, "%s.%s", CRLF, CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() end-message"); Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() end-message"); // Send QUIT sprintf(szMsgLine, "QUIT%s", CRLF); Check(send(hServer, szMsgLine, strlen(szMsgLine), 0), "send() QUIT"); Check(recv(hServer, szBuffer, sizeof(szBuffer), 0), "recv() QUIT"); // Report message has been sent cout<< "Sent " << argv[4] << " as email message to " << szToAddr << endl; // Close server socket and prepare to exit. closesocket(hServer); WSACleanup(); _getch(); return 0; }

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  • Does it make sense to have several UDP ports ready? Will packets be dropped?

    - by Gubatron
    I'm coding a networking application on Android. I'm thinking of having a single UDP port and Datagram socket that receives all the datagrams that are sent to it and then have different processing queues for these messages. I'm doubting if I should have a second or third UDP socket on standby. Some messages will be very short (100bytes or so), but others will have to transfer files. My concern is, will the Android kernel drop the small messages if it's too busy handling the bigger ones?

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  • n00b: receive input over TCP/IP and use it to update HTML

    - by mawg
    This has got to be a FAQ, so can someone please just direct me to a "network programming for dummies" URL? The server wants to push information to a client or broadcast to all, when an event happens - as opposed to the clients constantly polling the server "just in case". The client then updates a browser page display. How do I do that? (toldya it was a n00b question) Should I have a thread which receives info on a socket and then writes it to a database which the browser display (PHP) can process with an HTML refresh tag, or what? Sorry to sound so dumb.

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  • Listening socket

    - by hoodoos
    I got a strange problem, I never actually expirienced this before, here is the code of the server (client is firefox in this case), the way I create it: _Socket = new Socket( AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp ); _Socket.Bind( new IPEndPoint( Settings.IP, Settings.Port ) ); _Socket.Listen( 1000 ); _Socket.Blocking = false; the way i accept connection: while( _IsWorking ) { if( listener.Socket.Poll( -1, SelectMode.SelectRead ) ) { Socket clientSocket = listener.Socket.Accept(); clientSocket.Blocking = false; clientSocket.SetSocketOption( SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true ); } } So I'm expecting it hang on listener.Socket.Poll till new connection comes, but after first one comes it hangs on poll forever. I tried to poll it constantly with smaller delay, let's say 10 microseconds, then it never goes in SelectMode.SelectRead. I guess it maybe somehow related on client's socket reuse? Maybe I don't shutdown client socket propertly and client(firefox) decides to use an old socket? I disconnect client socket this way: Context.Socket.Shutdown( SocketShutdown.Both ); // context is just a wrapper around socket Context.Socket.Close(); What may cause that problem?

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  • Put a java socket-like program in a cloud service

    - by user293030
    I developed a server side java program, basically is a relay server so I can easily pass NATs and firewalls. The program works, but now I need a cloud service to host it. Do you know where/how I can put a java socket-like program in the cloud? Obviously, I prefer a free service or at least a free service while I'm testing. Thank you!

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  • java timer and socket problem

    - by Guru
    Hi there, I'm trying to make a program which listens to the client input stream by using socket programming and timer but whenever timer executes.. it gets hanged Please help me out here is the code... private void jButton1MouseClicked(java.awt.event.MouseEvent evt) { // TODO add your handling code here: try { ServerUserName=jTextField1.getText(); ss=new ServerSocket(5000); jButton1.enable(false); jTextArea1.enable(true); jTextField2.enable(true); Timer t=new Timer(2000, new ActionListener() { public void actionPerformed(ActionEvent e) { try { s=ss.accept(); InputStream is=s.getInputStream(); DataInputStream dis=new DataInputStream(is); jTextArea1.append(dis.readUTF()); } catch(IOException IOE) { } catch(Exception ex) { setLbl(ex.getMessage()); } } }); t.start(); } catch(IOException IOE) { } } Thanks in advance

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  • Python : How to close a UDP socket while is waiting for data in recv ?

    - by alexroat
    Hello, let's consider this code in python: import socket import threading import sys import select class UDPServer: def __init__(self): self.s=None self.t=None def start(self,port=8888): if not self.s: self.s=socket.socket(socket.AF_INET, socket.SOCK_DGRAM) self.s.bind(("",port)) self.t=threading.Thread(target=self.run) self.t.start() def stop(self): if self.s: self.s.close() self.t.join() self.t=None def run(self): while True: try: #receive data data,addr=self.s.recvfrom(1024) self.onPacket(addr,data) except: break self.s=None def onPacket(self,addr,data): print addr,data us=UDPServer() while True: sys.stdout.write("UDP server> ") cmd=sys.stdin.readline() if cmd=="start\n": print "starting server..." us.start(8888) print "done" elif cmd=="stop\n": print "stopping server..." us.stop() print "done" elif cmd=="quit\n": print "Quitting ..." us.stop() break; print "bye bye" It runs an interactive shell with which I can start and stop an UDP server. The server is implemented through a class which launches a thread in which there's a infinite loop of recv/*onPacket* callback inside a try/except block which should detect the error and the exits from the loop. What I expect is that when I type "stop" on the shell the socket is closed and an exception is raised by the recvfrom function because of the invalidation of the file descriptor. Instead, it seems that recvfrom still to block the thread waiting for data even after the close call. Why this strange behavior ? I've always used this patter to implements an UDP server in C++ and JAVA and it always worked. I've tried also with a "select" passing a list with the socket to the xread argument, in order to get an event of file descriptor disruption from select instead that from recvfrom, but select seems to be "insensible" to the close too. I need to have a unique code which maintain the same behavior on Linux and Windows with python 2.5 - 2.6. Thanks.

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  • socket.error: [Errno 10054]

    - by C0d3r
    import socket, sys if len(sys.argv) !=3 : print "Usage: ./supabot.py <host> <port>" sys.exit(1) irc = sys.argv[1] port = int(sys.argv[2]) sck = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sck.connect((irc, port)) sck.send('NICK supaBOT\r\n') sck.send('USER supaBOT supaBOT supaBOT :supaBOT Script\r\n') sck.send('JOIN #darkunderground' + '\r\n') data = '' while True: data = sck.recv(1024) if data.find('PING') != -1: sck.send('PONG ' + data.split() [1] + '\r\n') print data elif data.find('!info') != -1: sck.send('PRIVMSG #darkunderground supaBOT v1.0 by sourD' + '\r\n') print sck.recv(1024) when I run this code I get this error.. socket.error: [Errno 10054] An existing connection was forcibly closed by the remote host it says that the error is in line 16, in data = sck.recv(1024)

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  • breaking out from socket select

    - by kamziro
    I have a loop which basically calls this every few seconds (after the timeout): while(true){ if(finished) return; switch(select(FD_SETSIZE, &readfds, 0, 0, &tv)){ case SOCKET_ERROR : report bad stuff etc; return; default : break; } // do stuff with the incoming connection } So basically for every few seconds (which is specified by tv), it reactivates the listening. This is run on thread B (not a main thread). There are times when I want to end this acceptor loop immediately from thread A (main thread), but seems like I have to wait until the time interval finishes.. Is there a way to disrupt the select function from another thread so thread B can quit instantly?

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  • recvfrom returns invalid argument when *from* is passed

    - by Aditya Sehgal
    I am currently writing a small UDP server program in linux. The UDP server will receive packets from two different peers and will perform different operations based on from which peer it received the packet. I am trying to determine the source from where I receive the packet. However, when select returns and recvfrom is called, it returns with an error of Invalid Argument. If I pass NULL as the second last arguments, recvfrom succeeds. I have tried declaring fromAddr as struct sockaddr_storage, struct sockaddr_in, struct sockaddr without any success. Is their something wrong with this code? Is this the correct way to determine the source of the packet? The code snippet follows. ` /*TODO : update for TCP. use recv */ if((pkInfo->rcvLen=recvfrom(psInfo->sockFd, pkInfo->buffer, MAX_PKTSZ, 0, /* (struct sockaddr*)&fromAddr,*/ NULL, &(addrLen) )) < 0) { perror("RecvFrom failed\n"); } else { /*Apply Filter */ #if 0 struct sockaddr_in* tmpAddr; tmpAddr = (struct sockaddr_in* )&fromAddr; printf("Received Msg From %s\n",inet_ntoa(tmpAddr->sin_addr)); #endif printf("Packet Received of len = %d\n",pkInfo->rcvLen); } `

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