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• How to pass data to another droid device when the other device isn't expecting it

  - by James Black

  I am working on an application and one feature that would make it really useful is the ability to share some information, but the other device may not be expecting the data to be sent. For example, if I am reading a really good book, and I realize that a friend may like it, I could use an application to send the data to him, so he could order the book from Amazon. But, since he isn't expecting the data, I would hate for the application to be polling a server every so often, as that will be needlessly draining the battery. Ideally it would be great if there was a way to make a phone call to the target device, send a data packet and end the call. If it could be done and prevent the phone from ringing, then it would be very useful to me. I am curious if there is some way to send data between devices without polling.

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• How to gain greater control of network packets on Android

  - by mauvehead

  I'm looking to design an application that will require some deep control over IP packets. Looking over the reference guide on the developers site at Android I see very limited control over packets from java.net:SocketOptions and java.net:DatagramPacket. Specifically I'm looking to control the individual bits within the packet to set TCP Flags, SYN/ACK/RST, and so forth. Based on the docs I am assuming I cannot do this within the Java API provided by Android and I'm guessing I'll have to do it some other way? Anyone have any insight on this?

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• Java Socket fails to transmit data over the network

  - by Mark Griffin

  I'm experiencing a bizarre problem with sockets between a Java Knopflerfish client bundle and a PHP (CLI, not web) server. The client/server pair work fine when both are located on the localhost, and all data is transmitted successfully. However, when the Java client exists on a different machine, connections to the server are successful, but no data is received by the PHP script. Packet analysis confirms that the data sent by the Java client is received on by the server - PHP just seems to have problems getting its hands on it. As a further note, I've done some tests with telnet as the client. The PHP server script receives all data fine from any host. This leads me to believe that the problem has something to do with the way java is setting up the socket or that there is some networking issue that I'm not familiar with. Any thoughts would be appreciated. Can post code samples if desired.

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• Are there any modern platforms with non-IEEE C/C++ float formats?

  - by Patrick Niedzielski

  Hi all, I am writing a video game, Humm and Strumm, which requires a network component in its game engine. I can deal with differences in endianness easily, but I have hit a wall in attempting to deal with possible float memory formats. I know that modern computers have all a standard integer format, but I have heard that they may not all use the IEEE standard for floating-point integers. Is this true? While certainly I could just output it as a character string into each packet, I would still have to convert to a "well-known format" of each client, regardless of the platform. The standard printf() and atod() would be inadequate. Please note, because this game is a Free/Open Source Software program that will run on GNU/Linux, *BSD, and Microsoft Windows, I cannot use any proprietary solutions, nor any single-platform solutions. Cheers, Patrick

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• Building a webserver, client doesn't acknowledge HTTP 200 OK frame.

  - by Evert

  Hi there, I'm building my own webserver based on a tutorial. I have found a simple way to initiate a TCP connection and send one segment of http data (the webserver will run on a microcontroller, so it will be very small) Anyway, the following is the sequence I need to go through: receive SYN send SYN,ACK receive ACK (the connection is now established) receive ACK with HTTP GET command send ACK send FIN,ACK with HTTP data (e.g 200 OK) receive FIN,ACK <- I don't recieve this packet! send ACK Everything works fine until I send my acknowledgement and HTTP 200 OK message. The client won't send an acknowledgement to those two packages and thus no webpage is being displayed. I've added a pcap file of the sequence how I recorded it with wireshark. Pcap file: http://cl.ly/5f5 (now it's the right data) All sequence and acknowledgement numbers are correct, checksum are ok. Flags are also right. I have no idea what is going wrong.

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• Unit testing UDP socket handling code

  - by JustJeff

  Are there any 'good' ways to cause a thread waiting on a recvfrom() call to become unblocked and return with an error? The motivation for this is to write unit tests for a system which includes a unit that reads UDP datagrams. One of the branches handles errors on the recvfrom call itself. The code isn't required to distinguish between different types of errors, it just has to set a flag. I've thought of closing the socket from another thread, or do a shutdown on it, to cause recvfrom to return with an error, but this seems a bit heavy handed. I've seen mention elsewhere that sending an over-sized packet would do it, and so set up an experiment where a 16K buffer was sent to a recvfrom waiting for just 4K, but that didn't result in an error. The recvfrom just return 4096, to indicate it had gotten that many bytes.

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• How to implement blocking request-reply using Java concurrency primitives?

  - by Uri

  My system consists of a "proxy" class that receives "request" packets, marshals them and sends them over the network to a server, which unmarshals them, processes, and returns some "response packet". My "submit" method on the proxy side should block until a reply is received to the request (packets have ids for identification and referencing purposes) or until a timeout is reached. If I was building this in early versions of Java, I would likely implement in my proxy a collection of "pending messages ids", where I would submit a message, and wait() on the corresponding id (with a timeout). When a reply was received, the handling thread would notify() on the corresponding id. Is there a better way to achieve this using an existing library class, perhaps in java.util.concurrency? If I went with the solution described above, what is the correct way to deal with the potential race condition where a reply arrives before wait() is invoked?

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• Function that copies into byte vector reverses values

  - by xeross

  Hey, I've written a function to copy any variable type into a byte vector, however whenever I insert something it gets inserted in reverse. Here's the code. template <class Type> void Packet::copyToByte(Type input, vector<uint8_t>&output) { copy((uint8_t*) &input, ((uint8_t*) &input) + sizeof(Type), back_inserter(output)); } Now whenever I add for example a uint16_t with the value 0x2f1f it gets inserted as 1f 2f instead of the expected 2f 1f. What am I doing wrong here ? Regards, Xeross

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• Excel data connection - remove header row?

  - by ekoner

  The excel spreadsheet is connecting to SQL server 2005 using the connection string below: Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=True;Initial Catalog=XXXXXX;Data Source=XXXXXX;Extended Properties="HDR=No";Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Workstation ID=XXXXXX;Use Encryption for Data=False;Tag with column collation when possible=False It then pulls data from a view into Excel. The business user wants this information without a header row. This will allow her to review then save as a "headless" csv in SAGE file format. I attempted to alter the connection string by adding HDR=No but that hasn't worked. Additionally, I can't delete the header row. Deleting the content replaces the column names with "Column 1" etc. Any ideas appreciated!

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• .NET values lookup

  - by Maciej

  Hi, I have a feeling of missing something obvious. UDP receiver application. It holds a collection of valid UDP sender IPs - only guys with IP on that list will be considered. Since that list must be looked at on every packet and UDPs are so volatile, that operation must be maximum fast. Good choice is Dictionary but it is a key-value structure and what I actually need here is a dictionary-like (hash lookup) key only structure. Is there something like that? Small annoyance rather than a bug but still. I can still use Dictionary Thanks, M.

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• Invalidating session before iPhone application quits

  - by tartox

  Hello I would like to tell the server to invalidate an ongoing session when the user quits the iPhone application. In the app delegate, I send a request to the server in the (void)applicationWillTerminate:(UIApplication *)application method. I am not waiting for a server answer, I just want to send the request and quit. However I cant see any packet leaving the application. The same code in another place works fine. Session has a limited duration anyway and the server will invalidate it after a while, but I would prefer to do it nicely when leaving application. Is it normal that no NSURLConnection can be established from the applicationWillTerminate method ? Thank you.

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• Writing email sniffer

  - by Rampage

  Hello, I am interested in writing an email sniffer that saves all emails sent via web based clients to hd, but I can't work out how to do this. How can I catch HTTPS mail before it is encrypted? I would really appriciate some useful info. I cannot find anything information on the web. There's a program called HTTP Analyzer V5 that does the exact thing I want to make. How should I start? If I make a packet sniffer, it's useless because all data is encrypted. Is there any other option?

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• C# Socket Server

  - by Snoopy

  In .NET 3.5 a new socket classes was released: http://msdn.microsoft.com/en-us/library/bb968780.aspx i found a sample but some questions regarding best practicses are remaining: http://code.msdn.microsoft.com/nclsamples/Wiki/View.aspx?title=Socket%20Performance m_numConnections (the maximum number of connections the sample is designed to handle simultaneously) is probably equal to the amount of cpu cores i have. m_receiveBufferSize is the size for one packet? like 8kb? how should i handle a length byte? opsToPreAlloc i dont understand. is this if i code a transparent proxy? Regarding the multithreading, what should be used? The reactive extension seem to be a good choice. Has anyone tried this in a real world project? Are there better options? I had bad experiences with the .NET thread pool in the past.

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• MSCRYPTO: How to import RSA key from pkcs#12 into Microsoft Enhanced RSA and AES CSP?

  - by lsh123

  According to the MSDN (http://msdn.microsoft.com/en-us/library/aa387314%28v=VS.85%29.aspx) the PFXImportCertStore function imports the cert/key into Base CSP (MS_STRONG_PROV) or Enhanced CSP (MS_ENHANCED_PROV). However, to use RSA/SHA2 signatures, I need to import the key into the Enhanced RSA and AES CSP (MS_ENH_RSA_AES_PROV) and I can't find a way to do it. The documentation mentions "provider name" from the PFX packet, but I can't find any way to set it for a pkcs12 file generated by a 3rd party (e.g. OpenSSL). Thank you in advance.

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• C# socket blocking behavior

  - by Gearoid Murphy

  My situation is this : I have a C# tcp socket through which I receive structured messages consisting of a 3 byte header and a variable size payload. The tcp data is routed through a network of tunnels and is occasionally susceptible to fragmentation. The solution to this is to perform a blocking read of 3 bytes for the header and a blocking read of N bytes for the variable size payload (the value of N is in the header). The problem I'm experiencing is that occasionally, the blocking receive operation returns a partial packet. That is, it reads a volume of bytes less than the number I explicitly set in the receive call. After some debugging, it appears that the number of bytes it returns is equal to the number of bytes in the Available property of the socket before the receive op. This behavior is contrary to my expectation. If the socket is blocking and I explicitly set the number of bytes to receive, shouldn't the socket block until it recv's those bytes?, any help, pointers, etc would be much appreciated.

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• How to recive more than 65000 bytes in C++ socket using recv()

  - by Mr.Cool

  I am developing a client server application (TCP) in Linux using C++. I want to send more than 65,000 bytes at the same time. In TCP, the maximum packet size is 65,635 bytes only. How can I send the entire bytes without loss? Following is my code at server side. //Receive the message from client socket if((iByteCount = recv(GetSocketId(), buffer, MAXRECV, MSG_WAITALL)) > 0) { printf("\n Received bytes %d\n", iByteCount); SetReceivedMessage(buffer); return LS_RESULT_OK; } If I use MSG_WAITALL it takes a long time to receive the bytes so how can I set the flag to receive more than 10 lakhs bytes at time.

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• Threading and pcap issues.

  - by cftmon

  I have a GUI program that allows a user a scan a network, the issue is that when the pcap_loop function is called, my GUI program becomes unresponsive.(the pcap_loop blocks the current thread). When i try to use pthreads, i got a SIGSEGV fault at the pcap_loop function.Why?It's as if the thread can't see the procPacket function itself. void procPacket(u_char *arg, const struct pcap_pkthdr *pkthdr, const u_char *packet) { //show packets here } void* pcapLooper(void* param) { pcap_t* handler = (pcap_t*) param; pcap_loop(handler, 900 ,procPacket, NULL ); } //some function that runs when a button is pressed //handler has been opened through pcap_open_live pthread_t scanner; int t = pthread_create(&scanner,NULL,&pcapLooper, &handler ); if(t) { std::cout << "failed" << std::endl; } pthread_join(scanner,NULL); //do other stuff.

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• MySQL PHP incompatibility.

  - by Evernoob

  Ok maybe I've overlooked something really simple here, but I can't seem to figure this out. I'm running WAMP locally, but connecting to a remote MySQL database. The local version of PHP is the latest 5.3.0. One of the remote databases, being version 5.0.45 works fine. However, the other remote database I'm trying to connect to, which is version 5.0.22 throws the following error before dying: Warning: mysql_connect() [function.mysql-connect]: OK packet 6 bytes shorter than expected. PID=5880 in ... Warning: mysql_connect() [function.mysql-connect]: mysqlnd cannot connect to MySQL 4.1+ using old authentication in ... WTF? UPDATE: Reverting to PHP 5.2.* i.e. anything lower than 5.3.0 resolves the problem completely. As long as I am not running 5.3.0 I can connect to both databases. I'm not sure what the explanation is for this weirdness.

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• Is there a way in CXF to disable the SoapCompressed header for debugging purposes?

  - by Don Branson

  I'm watching CXF service traffic using DonsProxy, and the CXF client sends an HTTP header "SoapCompressed": HttpHeadSubscriber starting... Sender is CLIENT at 127.0.0.1:2680 Packet ID:0-1 POST /yada/yada HTTP/1.1 Content-Type: text/xml; charset=UTF-8 SoapCompressed: true Accept-Encoding: gzip,gzip;q=1.0, identity; q=0.5, *;q=0 SOAPAction: "" Accept: */* User-Agent: Apache CXF 2.2 Cache-Control: no-cache Pragma: no-cache Host: localhost:9090 Connection: keep-alive Transfer-Encoding: chunked I'd like to turn SoapCompressed off in my dev environment so that I can see the SOAP on the wire. I've searched Google and grepped the CXF source code, but don't see anything in the docs or code that reference this. Any idea how to make the client send "SoapCompressed: off" instead, without routing it through Apache HTTPD or the like? Is there a way to configure it at the CXF client, in other words?

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• Create multiple TCP Connections in C# then wait for data

  - by Ryan French

  Hi Everyone, I am currently creating a Windows Service that will create TCP connections to multiple machines (same socket on all machines) and then listen for 'events' from those machines. I am attempting to write the code to create a connection and then spawn a thread that listens to the connection waiting for packets from the machine, then decode the packets that come through, and call a function depending on the payload of the packet. The problem is I'm not entirely sure how to do that in C#. Does anyone have any helpful suggestions or links that might help me do this? Thanks in advance for any help!

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• Why are nanosleep() and usleep() too slow?

  - by user351990

  I have a program that generates packets to send to a receiver. I need an efficient method of introducing a small delay between the sending of each packet so as not to overrun the receiver. I've tried usleep() and nanosleep() but they seem to be too slow. I've implemented a busy wait loop and had more success, but it's not the most efficient method, I know. I'm interested in anyone's experiences in trying to do what I'm doing. Do others find usleep() and nanosleep() to function well for this type of application? Thanks, Danny Llewallyn

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• Foolishness Check: PHP Class finds Class file but not Class in the file.

  - by Daniel Bingham

  I'm at a loss here. I've defined an abstract superclass in one file and a subclass in another. I have required the super-classes file and the stack trace reports to find an include it. However, it then returns an error when it hits the 'extends' line: Fatal error: Class 'HTMLBuilder' not found in View/Markup/HTML/HTML4.01/HTML4_01Builder.php on line 7. I had this working with another class tree that uses factories a moment ago. I just added the builder layer in between the factories and the consumer. The factory layer looked almost exactly the same in terms of includes and dependencies. So that makes me think I must have done something silly that's causes the HTMLBuilder.php file to not be included correctly or interpreted correctly or some such. Here's the full stack trace (paths slightly altered): # Time Memory Function Location 1 0.0001 53904 {main}( ) ../index.php:0 2 0.0002 67600 require_once( 'View/Page.php' ) ../index.php:3 3 0.0003 75444 require_once( 'View/Sections/SectionFactory.php' ) ../Page.php:4 4 0.0003 81152 require_once( 'View/Sections/HTML/HTMLSectionFactory.php' ) ../SectionFactory.php:3 5 0.0004 92108 require_once( 'View/Sections/HTML/HTMLTitlebarSection.php' ) ../HTMLSectionFactory.php:5 6 0.0005 99716 require_once( 'View/Markup/HTML/HTMLBuilder.php' ) ../HTMLTitlebarSection.php:3 7 0.0005 103580 require_once( 'View/Markup/MarkupBuilder.php' ) ../HTMLBuilder.php:3 8 0.0006 124120 require_once( 'View/Markup/HTML/HTML4.01/HTML4_01Builder.php' ) ../MarkupBuilder.php:3 Here's the code in question: Parent class (View/Markup/HTML/HTMLBuilder.php): <?php require_once('View/Markup/MarkupBuilder.php'); abstract class HTMLBuilder extends MarkupBuilder { public abstract function getLink($text, $href); public abstract function getImage($src, $alt); public abstract function getDivision($id, array $classes=NULL, array $children=NULL); public abstract function getParagraph($text, array $classes=NULL, $id=NULL); } ?> Child Class, (View/Markup/HTML/HTML4.01/HTML4_01Builder.php): <?php require_once('HTML4_01Factory.php'); require_once('View/Markup/HTML/HTMLBuilder.php'); class HTML4_01Builder extends HTMLBuilder { private $factory; public function __construct() { $this->factory = new HTML4_01Factory(); } public function getLink($href, $text) { $link = $this->factory->getA(); $link->addAttribute('href', $href); $link->addChild($this->factory->getText($text)); return $link; } public function getImage($src, $alt) { $image = $this->factory->getImg(); $image->addAttribute('src', $src); $image->addAttribute('alt', $alt); return $image; } public function getDivision($id, array $classes=NULL, array $children=NULL) { $div = $this->factory->getDiv(); $div->setID($id); if(!empty($classes)) { $div->addClasses($classes); } if(!empty($children)) { $div->addChildren($children); } return $div; } public function getParagraph($text, array $classes=NULL, $id=NULL) { $p = $this->factory->getP(); $p->addChild($this->factory->getText($text)); if(!empty($classes)) { $p->addClasses($classes); } if(!empty($id)) { $p->setID($id); } return $p; } } ?> I would appreciate any and all ideas. I'm at a complete loss here as to what is going wrong. I'm sure it's something stupid I just can't see...

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• How to extract comment out of header file using python, perl, or sed?

  - by WilliamKF

  I have a header file like this: /* * APP 180-2 ALG-254/258/772 implementation * Last update: 03/01/2006 * Issue date: 08/22/2004 * * Copyright (C) 2006 Somebody's Name here * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef HEADER_H #define HEADER_H /* More comments and C++ code here. */ #endif /* End of file. */ And I wish to extract out the contents of the first C style comment only and drop the " *" at the start of each line to get a file with the following contents: APP 180-2 ALG-254/258/772 implementation Last update: 03/01/2006 Issue date: 08/22/2004 Copyright (C) 2006 Somebody's Name here All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the project nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Please suggest an easy way to do this with Python, Perl, sed, or some other way on Unix. Preferably as a one-liner.

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• Maximum number of bytes that can be sent on a TCP connection

  - by iamrohitbanga

  I initially assumed that since tcp has a sequence number field of 32 bits and each byte sent on a tcp connection is labeled with a unique number, maximum number of bytes that can be sent on a tcp connection is about 2^32-1 or 2^32-2 (which?). but now I feel that since TCP is a sliding window protocol, the wraparound of sequence numbers during the connection should not have an affect on the maximum number of bytes that can be sent over a tcp connection as long as the when wraparound occurs the old packet is no longer in the network (it is sent after 2*MSL). What is the correct answer?

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• c++ networking issue- retrnsmittion without ccongestion

  - by gln

  I wrote an application in c++ which send data over tcp connection to several machines.as part of the protocol I use in my application, the other side sends hearbeat messages from time to time, then I know that the connection is still alive. now, I want this application to work on 100 machines or more at the same time. but, I see that sometimes I don't get these heartbeat messages although they sent: I see in wireshark that the packet arrived, then my OS doesn't ack on this message, so there are some retransmit without any ack from my OS. if I look in the window size property - I saw that there is no issue in this part. what can be the root cause for this behavior? it is something in my code that I should change? this is my select code: int res = select(fdCount, &readFds, NULL, NULL, NULL ); I'm using server 2008 r2. Please help me! thanks

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