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  • TCP Flow control in AS3?

    - by Jeremy Stanley
    I am currently working on a Flash socket client for a pre-existing service/standard. The service uses TCP flow control to throttle itself and the Flash socket is reading in everything as fast as it can despite not being able to process it as fast as it's being taken in. This causes the bytesAvailable on the socket to keep increasing and the server never knows that the client has fallen behind. In short, is there any way to limit the size of bytesAvailable for a Flash Socket object or throttle it in some other way? Note: Rewriting the server isn't a viable option at the current time as it's a standard and the client's utility drops immensely if server-side changes are needed

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  • How to to icmps and traceroutes in Java

    - by Ricardo
    For some reason i cannot even phantom, Java does not have primitives for ICMPs and traceroute. Any idea how to overcome this? Basically im building code that should run in *nix and windows, and need a piece of code that will run in both platforms.. Thanks!

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  • Unable to connect on socket across different networks.

    - by maleki
    I am having trouble connecting my online application to others across another network. I am able to give them the hostAddress to connect when we are on the same network but when we are doing it across the internet the generated host address doesn't allow a connection, nor does using the ip address gotten from online sites such as whatismyip.com My biggest issue isn't debugging this code, because it works over intra-network but The server doesn't see attempts when we try to move to different networks. Also, the test ip I am using is 2222. InetAddress addr = InetAddress.getLocalHost(); String hostname = addr.getHostName(); System.out.println("Hostname: " + hostname); System.out.println("IP: " + addr.getHostAddress()); I display the host to the server when it is starting if (isClient) { System.out.println("Client Starting.."); clientSocket = new Socket(host, port_number); } else { System.out.println("Server Starting.."); echoServer = new ServerSocket(port_number); clientSocket = echoServer.accept(); System.out.println("Warning, Incoming Game.."); }

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  • Marshal.PtrToStructure (and back again) and generic solution for endianness swapping

    - by cgyDeveloper
    I have a system where a remote agent sends serialized structures (from and embedded C system) for me to read and store via IP/UDP. In some cases I need to send back the same structure types. I thought I had a nice setup using Marshal.PtrToStructure (receive) and Marshal.StructureToPtr (send). However, a small gotcha is that the network big endian integers need to be converted to my x86 little endian format to be used locally. When I'm sending them off again, big endian is the way to go. Here are the functions in question: private static T BytesToStruct<T>(ref byte[] rawData) where T: struct { T result = default(T); GCHandle handle = GCHandle.Alloc(rawData, GCHandleType.Pinned); try { IntPtr rawDataPtr = handle.AddrOfPinnedObject(); result = (T)Marshal.PtrToStructure(rawDataPtr, typeof(T)); } finally { handle.Free(); } return result; } private static byte[] StructToBytes<T>(T data) where T: struct { byte[] rawData = new byte[Marshal.SizeOf(data)]; GCHandle handle = GCHandle.Alloc(rawData, GCHandleType.Pinned); try { IntPtr rawDataPtr = handle.AddrOfPinnedObject(); Marshal.StructureToPtr(data, rawDataPtr, false); } finally { handle.Free(); } return rawData; } And a quick example structure that might be used like this: byte[] data = this.sock.Receive(ref this.ipep); Request request = BytesToStruct<Request>(ref data); Where the structure in question looks like: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)] private struct Request { public byte type; public short sequence; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 5)] public byte[] address; } What (generic) way can I swap the endianness when marshalling the structures? My need is such that the locally stored 'public short sequence' in this example will be little-endian for displaying to the user. I don't want to have to swap the endianness on a structure-specific way. My first thought was to use Reflection, but I'm not very familiar with that feature. Also, I hoped that there would be a better solution out there that somebody could point me towards. Thanks in advance :)

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  • java BufferedReader specific length returns NUL characters

    - by Bastien
    I have a TCP socket client receiving messages (data) from a server. messages are of the type length (2 bytes) + data (length bytes), delimited by STX & ETX characters. I'm using a bufferedReader to retrieve the two first bytes, decode the length, then read again from the same bufferedReader the appropriate length and put the result in a char array. most of the time, I have no problem, but SOMETIMES (1 out of thousands of messages received), when attempting to read (length) bytes from the reader, I get only part of it, the rest of my array being filled with "NUL" characters. I imagine it's because the buffer has not yet been filled. char[] bufLen = new char[2]; _bufferedReader.read(bufLen); int len = decodeLength(bufLen); char[] _rawMsg = new char[len]; _bufferedReader.read(_rawMsg); return _rawMsg; I solved the problem in several iterative ways: first I tested the last char of my array: if it wasn't ETX I would read chars from the bufferedReader one by one until I would reach ETX, then start over my regular routine. the consequence is that I would basically DROP one message. then, in order to still retrieve that message, I would find the first occurence of the NUL char in my "truncated" message, read & store additional characters one at a time until I reached ETX, and append them to my "truncated" messages, confirming length is ok. it works also, but I'm really thinking there's something I could do better, like checking if the total number of characters I need are available in the buffer before reading it, but can't find the right way to do it... any idea / pointer ? thanks !

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  • EPIPE blocks server

    - by timn
    I have written a single-threaded asynchronous server in C running on Linux: The socket is non-blocking and as for polling, I am using epoll. Benchmarks show that the server performs fine and according to Valgrind, there are no memory leaks or other problems. The only problem is that when a write() command is interrupted (because the client closed the connection), the server will encounter a SIGPIPE. I am doing the interrupted artifically by running the benchmarking utility "siege" with the parameter -b. It does lots of requests in a row which all work perfectly. Now I press CTRL-C and restart the "siege". Sometimes I am lucky and the server does not manage to send the full response because the client's fd is invalid. As expected errno is set to EPIPE. I handle this situation, execute close() on the fd and then free the memory related to the connection. Now the problem is that the server blocks and does not answer properly anymore. Here is the strace output: accept(3, {sa_family=AF_INET, sin_port=htons(50611), sin_addr=inet_addr("127.0.0.1")}, [16]) = 5 fcntl64(5, F_GETFD) = 0 fcntl64(5, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 epoll_ctl(4, EPOLL_CTL_ADD, 5, {EPOLLIN|EPOLLERR|EPOLLHUP|EPOLLET, {u32=158310248, u64=158310248}}) = 0 epoll_wait(4, {{EPOLLIN, {u32=158310248, u64=158310248}}}, 128, -1) = 1 read(5, "GET /user/register HTTP/1.1\r\nHos"..., 4096) = 161 write(5, "HTTP/1.1 200 OK\r\nContent-Type: t"..., 106) = 106 <<<<< write(5, "00001000\r\n", 10) = -1 EPIPE (Broken pipe) <<<<< Why did the previous write() work fine but not this one? --- SIGPIPE (Broken pipe) @ 0 (0) --- As you can see, the client establishes a new connection which consequently is accepted. Then, it's added to the EPOLL queue. epoll_wait() signalises that the client sent data (EPOLLIN). The request is parsed and and a response is composed. Sending the headers works fine but when it comes to the body, write() results in an EPIPE. It is not a bug in "siege" because it blocks any incoming connections, no matter from which client.

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  • Multiple Socket Connections

    - by BSchlinker
    I need to write a server which accepts connections from multiple client machines, maintains track of connected clients and sends individual clients data as necessary. Sometimes, all clients may be contacted at once with the same message, other times, it may be one individual client or a group of clients. Since I need confirmation that the clients received the information and don't want to build an ACK structure for a UDP connection, I decided to use a TCP streaming method. However, I've been struggling to understand how to maintain multiple connections and keep them idle. I seem to have three options. Use a fork for each incoming connection to create a separate child process, use pthread_create to create an entire new thread for each process, or use select() to wait on all open socket IDs for a connection. Recommendations as to how to attack this? I've begun working with pthreads but since performance will likely not be an issue, multicore processing is not necessary and perhaps there is a simpler way.

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  • How to cast sockaddr_storage and avoid breaking strict-aliasing rules

    - by sinoth
    I'm using Beej's Guide to Networking and came across an aliasing issue. He proposes a function to return either the IPv4 or IPv6 address of a particular struct: 1 void *get_in_addr( struct sockaddr *sa ) 2 { 3 if (sa->sa_family == AF_INET) 4 return &(((struct sockaddr_in*)sa)->sin_addr); 5 else 6 return &(((struct sockaddr_in6*)sa)->sin6_addr); 7 } This causes GCC to spit out a strict-aliasing error for sa on line 3. As I understand it, it is because I call this function like so: struct sockaddr_storage their_addr; ... inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), connection_name, sizeof connection_name); I'm guessing the aliasing has to do with the fact that the their_addr variable is of type sockaddr_storage and another pointer of a differing type points to the same memory. Is the best way to get around this sticking sockaddr_storage, sockaddr_in, and sockaddr_in6 into a union? It seems like this should be well worn territory in networking, I just can't find any good examples with best practices. Also, if anyone can explain exactly where the aliasing issue takes place, I'd much appreciate it.

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  • Python Socket Getting Connection Reset

    - by Ian
    I created a threaded socket listener that stores newly accepted connections in a queue. The socket threads then read from the queue and respond. For some reason, when doing benchmarking with 'ab' (apache benchmark) using a concurrency of 2 or more, I always get a connection reset before it's able to complete the benchmark (this is taking place locally, so there's no external connection issue). class server: _ip = '' _port = 8888 def __init__(self, ip=None, port=None): if ip is not None: self._ip = ip if port is not None: self._port = port self.server_listener(self._ip, self._port) def now(self): return time.ctime(time.time()) def http_responder(self, conn, addr): httpobj = http_builder() httpobj.header('HTTP/1.1 200 OK') httpobj.header('Content-Type: text/html; charset=UTF-8') httpobj.header('Connection: close') httpobj.body("Everything looks good") data = httpobj.generate() sent = conn.sendall(data) def http_thread(self, id): self.log("THREAD %d: Starting Up..." % id) while True: conn, addr = self.q.get() ip, port = addr self.log("THREAD %d: responding to request: %s:%s - %s" % (id, ip, port, self.now())) self.http_responder(conn, addr) self.q.task_done() conn.close() def server_listener(self, host, port): self.q = Queue.Queue(0) sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.bind( (host, port) ) sock.listen(5) for i in xrange(4): #thread count thread.start_new(self.http_thread, (i+1, )) while True: self.q.put(sock.accept()) sock.close() server('', 9999) When running the benchmark, I get totally random numbers of good requests before it errors out, usually between 4 and 500. Edit: Took me a while to figure it out, but the problem was in sock.listen(5). Because I was using apache benchmark with a higher concurrency (5 and up) it was causing the backlog of connections to pile up, at which point the connections started getting dropped by the socket.

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  • Why do IOExceptions occur in ReadableByteChannel.read()

    - by Steffen Heil
    Hi The specification of ReadableByteChannel.read() shows -1 as result value for end-of-stream. Moreover it specifies ClosedByInterruptExceptionas possible result if the thread is interrupted. Now I thought that would be all - and it is most of the time. However, now and then I get the following: java.io.IOException: Eine vorhandene Verbindung wurde vom Remotehost geschlossen at sun.nio.ch.SocketDispatcher.read0(Native Method) at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:25) at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:233) at sun.nio.ch.IOUtil.read(IOUtil.java:206) at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:236) at ... I do not unterstand why I don't get -1 in this case. Also this is not a clean exception, as I cannot catch it without catching any possible IOException. So here are my questions: Why is this exception thrown in the first place? Is it safe to assume that ANY exception thrown by read are about the socket being closed? Is all this the same for write()? And by the way: If I call SocketChannel.close() do I have to call SocketChannel.socket().close() as well or is this implied by the earlier? Thanks, Steffen

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  • Socket Bind Error

    - by rantravee
    Hi, I have a test application that opens a socket , sends something through this socket and then closes it . This is done in a loop for 5-10.000 times. The thing is that after 3,4000 iterations I get an error of this type : enter code here java.net.BindException: Address already in use: connect I even set the socket to be used immediattly, but the error persists enter code here try { out_server.write(m.ToByteArray()); socket_server.setReuseAddress(true); socket_server.close(); } catch(Exception e) { e.printStackTrace(); System.out.println(i+" unable to register with the server"); } What could I do to fix this ?

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  • In Perl, given two IO::Socket's how do I connect 1st socket's input to 2nd's output and vice versa?

    - by bodacydo
    Suppose I have made two connections in Perl with the help of IO::Socket. The first has socket $s1 and the second has socket $s2. Any ideas how can I connect them together so that whatever gets received from $s1 got sent to $s2 and whatever gets received from $s2 got sent to $s1? I can't understand how to do it. I don't know how to connect them together. I would expect to do something like $s1->stdin = $s2->stdout and $s2->stdin = $s1->stdout, but there are no such constructs in Perl. Please help me! Thanks, Boda Cydo.

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  • Problem with urllib

    - by Eva
    I wrote this code: import urllib proxies = {'http': 'http://112.65.135.54:8080/'} opener = urllib.FancyURLopener(proxies) r = opener.open("http://www.python.org/") print r.read() and when I execute it this program works fine, and send for me source code of python.org But when i use this: import urllib proxies = {'http': 'http://80.176.245.196:1080/'} opener = urllib.FancyURLopener(proxies) r = opener.open("http://www.python.org/") print r.read() this program does not send me the source code of python.org What am I going to do?

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  • 10035 error on a blocking socket

    - by Andrew
    Does anyone have any idea what could cause a 10035 error (EWOULDBLOCK) when reading on a blocking socket with a timeout? This is under Windows XP using the .NET framework version 3.5 socket library. I've never managed to get this myself, but one of my colleagues is getting it all the time. He's sending reasonably large amounts of data to a much slower device and then waiting for a response, which often gives a 10035 error. I'm wondering if there could be issues with TCP buffers filling up, but in that case I would expect the read to wait or timeount. The socket is definitely blocking, not non-blocking.

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  • recv returns old data

    - by anon
    This loop is supposed to take data from a socket line by line and put it in a buffer. For some reason, when there is no new data to return, recv returns the last couple lines it got. I was able to stop the bug by commenting out the first recv, but then I cant tell how long the next line will be. I know it's not a while(this->connected){ memset(buf, '\0', sizeof(buf)); recv(this->sock, buf, sizeof(buf), MSG_PEEK); //get length of next message ptr = strstr(buf, "\r\n"); if (ptr == NULL) continue; err = recv(this->sock, buf, (ptr-buf), NULL); //get next message printf("--%db\n%s\n", err, buf); tok[0] = strtok(buf, " "); for(i=1;tok[i-1]!=NULL;i++) tok[i] = strtok(NULL, " "); //do more stuff }

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  • how to serialize / deserialize classes defined in .proto (protobuf)

    - by make
    Hi, Could someone please help me with serialization/deserialization classes defined in .proto (protobuf). here is an exp that I am trying to build: file.proto message Data{ required string x1 = 1; required uint32 x2 = 2; required float x3 = 3; } message DataExge { repeated Data data = 1; } client.cpp ... void serialize(const DataExge &data_snd){ try { ofstream ofs("DataExge"); data_snd.SerializeToOstream(&ofs); } catch(exception &e) { cerr << "serialize/exception: " << e.what() << endl; exit(1); } } void deserialize(DataExge &data_rec){ try { ifstream ifs("DataExge"); data_rec.ParseFromIstream(&ifs); } catch(exception& e) { cerr << "deserialize/exception: " << e.what() << endl; exit(1); } } int main(){ ... DataExge dataexge; Data *dat = dataexge.add_data(); char *y1 = "operation1"; uint32_t y2 = 123 ; float y3 = 3.14; // assigning data to send() dat->set_set_x1(y1); dat->set_set_x2(y2); dat->set_set_x3(y3); //sending data to the client serialize(dataexge); if (send(socket, &dataexge, sizeof(dataexge), 0) < 0) { cerr << "send() failed" ; exit(1); } //receiving data from the server deserialize(dataexge); if (recv(socket, &dataexge, sizeof(dataexge), 0) < 0) { cerr << "recv() failed"; exit(1); } //printing received data cout << dat->x1() << "\n"; cout << dat->x2() << "\n"; cout << dat->x3() << "\n"; ... } server.cpp ... void serialize(const DataExge &data_snd){ try { ofstream ofs("DataExge"); data_snd.SerializeToOstream(&ofs); } catch(exception &e) { cerr << "serialize/exception: " << e.what() << endl; exit(1); } } void deserialize(DataExge &data_rec){ try { ifstream ifs("DataExge"); data_rec.ParseFromIstream(&ifs); } catch(exception& e) { cerr << "deserialize/exception: " << e.what() << endl; exit(1); } } int main(){ ... DataExge dataexge; Data *dat = dataexge.add_data(); //receiving data from the client deserialize(dataexge); if (recv(socket, &dataexge, sizeof(dataexge), 0) < 0) { cerr << "recv() failed"; exit(1); } //printing received data cout << dat->x1() << "\n"; cout << dat->x2() << "\n"; cout << dat->x3() << "\n"; // assigning data to send() dat->set_set_x1("operation2"); dat->set_set_x2(dat->x2() + 1); dat->set_set_x3(dat->x3() + 1.1); //sending data to the client serialize(dataexge); //error// I am getting error at this line ... if (send(socket, &dataexge, sizeof(dataexge), 0) < 0) { cerr << "send() failed" ; exit(1); } ... } Thanks for your help and replies -

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  • Problems in getting data from CFStreamCreatePairWithSocketToHost

    - by gkedmi
    Hi I'm building an iPhoe app with a socket to a PC app , I need to get an image from this PC app. It's my first time using "CFStreamCreatePairWithSocketToHost".After I establish the socket with "NSOperation" I call CFStreamClientContext streamContext = {0, self, NULL, NULL, NULL}; BOOL success = CFReadStreamSetClient(myReadStream, kMyNetworkEvents,MyStreamCallBack,&streamContext); CFReadStreamScheduleWithRunLoop(myReadStream, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode); then I call CFWriteStreamWrite(myWriteStream, &writeBuffer, 3); // Open read stream. if (!CFReadStreamOpen(myReadStream)) { // Notify error } . . . while(!cancelled && !finished) { SInt32 result = CFRunLoopRunInMode(kCFRunLoopDefaultMode, 0.25, NO); if (result == kCFRunLoopRunStopped || result == kCFRunLoopRunFinished) { break; } if (([NSDate timeIntervalSinceReferenceDate] - _lastRead) MyConnectionTimeout) { // Call timed out cancelled = YES; break; } // Also handle stream status CFStreamStatus status = CFReadStreamGetStatus(myReadStream); } and then when I get "kCFStreamEventHasBytesAvailable" I use while (CFReadStreamHasBytesAvailable(myReadStream)) { CFReadStreamRead(myReadStream, readBuffer, 1000); //and buffer the the bytes } It's unpredictable , sometimes I get the whole picture , sometime I got just part of it , and I can't understand what make the different. can someone has an idea what is wrong here? thanks

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  • Code Own Socket Server or Use Red5/ElectroServer on Amazon EC2?

    - by Travis
    I've been thinking for a long time about working on a multiplayer game in Flash. I need updates frequently enough that ajax requests won't work so I need to use a socket server. The system will eventually have enough objects/players that I would consider it an MMO. I would like to set up a scalable system on Amazon's EC2. (Which probably effects my choice of server) This architecture would hopefully allow the game to grow without many changes over time. (Using a domain decomposition technique or something similar) Heres my internal debate: Should I a. Code my own socket server in C++ or Java? b. Use the free and open source Red5 socket server for Flash? or c. Pay the licensing fees and go for Electroserver? I consider myself a decent developer, but am at an impasse as to what road to go down. I'm not sure if I, could develop/would need, the features of one of the prepackaged socket servers. I'm also not sure if the prepackaged servers would work well in an Amazon EC2 environment and take full advantage of its features. Any help or guidance would be greatly appreciated.

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  • CFSocketConnectToAddress and unrecognized selector sent to instance

    - by madmik3
    Hello, I am somewhat new to iPhone dev and I have been getting unrecognized selector when I call CFSocketConnectToAddress in this code. I think it might be something basic that I am doing wrong. Any idea? this is the complete error I get. NSInvalidArgumentException unrecognized selector sent to instance 0x3922170 0x3922170 is the calling class. - (BOOL)connect { CFSocketRef mySocket = CFSocketCreate(kCFAllocatorDefault, PF_INET, SOCK_DGRAM,IPPROTO_UDP, 0, socketCallback, NULL); @try { CFDataRef data = (CFDataRef)[_netService addresses]; CFSocketConnectToAddress(mySocket, data, 500); } @catch (NSException * e) { NSLog([e name]); NSLog([e reason]); } //char joke[] = "Why did the chicken cross the road?"; //CFSocketError err = CFSocketSendData(mySocket, joke, (strlen(joke)+1), 10); return true; } void socketCallback ( CFSocketRef s, CFSocketCallBackType callbackType, CFDataRef address, const void *data, void *info) { }

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  • socket.shutdown vs socket.close

    - by Jason Baker
    I recently saw a bit of code that looked like this (with sock being a socket object of course): sock.shutdown(socket.SHUT_RDWR) sock.close() What exactly is the purpose of calling shutdown on the socket and then closing it? If it makes a difference, this socket is being used for non-blocking IO.

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  • python socket.recv/sendall call blocking

    - by fsm
    Hi everyone. This post is incorrectly tagged 'send' since I cannot create new tags. I have a very basic question about this simple echo server. Here are some code snippets. client while True: data = raw_input("Enter data: ") mySock.sendall(data) echoedData = mySock.recv(1024) if not echoedData: break print echoedData server while True: print "Waiting for connection" (clientSock, address) = serverSock.accept() print "Entering read loop" while True: print "Waiting for data" data = clientSock.recv(1024) if not data: break clientSock.send(data) clientSock.close() Now this works alright, except when the client sends an empty string (by hitting the return key in response to "enter data: "), in which case I see some deadlock-ish behavior. Now, what exactly happens when the user presses return on the client side? I can only imagine that the sendall call blocks waiting for some data to be added to the send buffer, causing the recv call to block in turn. What's going on here? Thanks for reading!

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