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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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  • Finding an available network port on the machine

    - by Tomer Vromen
    I'm trying to implement a simple FTP server (a variation of the EFTP protocol) in linux. When a client connects and sends the PASV command, the server should respond with a port number, so the client can connect to that port to transmit the file. How can the server choose a port number? Do I need to iterate through all the ports from 1024 to 65535 until I find a port that the process can bind to? I know that calling bind() with 0 as the port automatically chooses the port to bind to, but then how can I know which port was chosen? Many thanks.

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  • Strange client's address returned throug accept(..) function.

    - by Negai
    Hi everyone, I'm a socket programming newbie. Here's a snippet: struct sockaddr_storage client_addr; ... client_addr_size = sizeof(client_addr); client_socket = accept( server_socket, (struct sockaddr *)&client_addr, &client_addr_size ); ... result = inet_ntop( AF_INET, &((struct sockaddr_in *)&client_addr)->sin_addr, client_addr_str, sizeof(client_addr_str) ); Whenever the client connects the address I get is 0.0.0.0 regardless from the host. Can anybody explain, what I'm doing wrong? Thanks.

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  • How do you handle live video streaming in Flash AS3?

    - by CodeJustin.com
    I've been dabbling with socket servers in Java and now I'm ready to get my feet wet with an idea I had. I would like to use python for my socket server and obviously AS3 for my client. I'm able to create a full chat using my own python socket server but I'm almost clueless what to do now that I want to add in LIVE video (want to make it a live video "chat"). I've found tutorials but they are for FMS and I can not afford that, also Red5 looked nice but couldn't find a live video tutorial off hand (plus I would have to switch to Red5 from my own socket server). So if someone could even nudge me into some resources on the subject (the subject of live video without using FMS) that would be very helpful, Google is failing me right now.

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  • How to create a simple Proxy to access web servers in C

    - by jesusiniesta
    Hi. I’m trying to create an small Web Proxy in C. First, I’m trying to get a webpage, sending a GET frame to the server. I don’t know what I have missed, but I am not receiving any response. I would really appreciate if you can help me to find what is missing in this code. int main (int argc, char** argv) { int cache_size, //size of the cache in KiB port, port_google = 80, dir, mySocket, socket_google; char google[] = "www.google.es", ip[16]; struct sockaddr_in socketAddr; char buffer[10000000]; if (GetParameters(argc,argv,&cache_size,&port) != 0) return -1; GetIP (google, ip); printf("ip2 = %s\n",ip); dir = inet_addr (ip); printf("ip3 = %i\n",dir); /* Creation of a socket with Google */ socket_google = conectClient (port_google, dir, &socketAddr); if (socket_google < 0) return -1; else printf("Socket created\n"); sprintf(buffer,"GET /index.html HTTP/1.1\r\n\r\n"); if (write(socket_google, (void*)buffer, LONGITUD_MSJ+1) < 0 ) return 1; else printf("GET frame sent\n"); strcpy(buffer,"\n"); read(socket_google, buffer, sizeof(buffer)); // strcpy(message,buffer); printf("%s\n", buffer); return 0; } And this is the code I use to create the socket. I think this part is OK, but I copy it just in case. int conectClient (int puerto, int direccion, struct sockaddr_in *socketAddr) { int mySocket; char error[1000]; if ( (mySocket = socket(AF_INET, SOCK_STREAM, 0)) == -1) { printf("Error when creating the socket\n"); return -2; } socketAddr->sin_family = AF_INET; socketAddr->sin_addr.s_addr = direccion; socketAddr->sin_port = htons(puerto); if (connect (mySocket, (struct sockaddr *)socketAddr,sizeof (*socketAddr)) == -1) { snprintf(error, sizeof(error), "Error in %s:%d\n", __FILE__, __LINE__); perror(error); printf("%s\n",error); printf ("-- Error when stablishing a connection\n"); return -1; } return mySocket; } Thanks!

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  • Suggestions on writing a TCP IP messaging system (Client/Server) using Delphi 2010

    - by Shane
    I would like to write a messaging system using TCP IP in Delphi 2010. I would like to hear what my best options are for using the standard delphi 2010 components/indy components for doing this. I would like to write a server which does the listening and forwarding of messages to all machines on the network running a client. 1.) a.) clients can send a message to server to be forwarded to all other clients b.) clients listen for messages from other senders (via server) and displays messages. 2.) a.) Server can send a message to all clients b.) Server forwards any messages from clients to all other clients thanks for any suggestions NOTE: I am not writing a instant messaging or chat program. This is merely a system where users can send alerts/messages to other users - they can not reply to each other! NO commercial, shareware, etc links - please! I would like to hear about how you would go about writing this type of system and what approachs you would take, and possibly the TCP IP messaging architecture you would use. Whether it be straight Winows API, Indy components, etc, etc.

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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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  • Close socket and select()

    - by kamziro
    So I need to close a particular connection, but the problem is another thread is, at the same time, doing a select() which has the socket as one of the file descriptors it's watching. Will the select() terminate gracefully, or will anything bad happen?

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  • How to maintain a persistant network-connection between two applications over a network?

    - by John
    I was recently approached by my management with an interesting problem - where I am pretty sure I am telling my bosses the correct information but I really want to make sure I am telling them the correct stuff. I am being asked to develop some software that has this function: An application at one location is constantly processing real-time data every second and only generates data if the underlying data has changed in any way. On the event that the data has changed send the results to another box over a network Maintains a persistent connection between the both machines, altering the remote box if for some reason the network connection went down From what I understand, I imagine that I need to do some reading on doing some sort of TCP/IP socket-level stuff. That way if the connection is dropped the remote location will be aware that the data it has received may be stale. However management seems to be very convinced that this can be accomplished using SOAP. I was under the impression that SOAP is more or less a way for a client to initiate a procedure from a server and get some results via the HTTP protocol. Am I wrong in assuming this? I haven't been able to find much information on how SOAP might be able to solve a problem like this. I feel like a lot of people around my office are using SOAP as a buzzword and that has generated a bit of confusion over what SOAP actually is - and is capable of. Any thoughts on how to accomplish this task would be appreciated!

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  • Flex: client / server messaging question (RPC or socket ?)

    - by Patrick
    hi, I'm building a Flex application, which is going to perform many server requests (let's say, that almost all interactions require an update from server). At the moment I'm using remote procedure calls for it. But I was wondering if using a socket would be better. In other terms, is maybe better to keep the connection alive rather then performing many calls in sequence ? For my demo app I only have 1 client. Is the number of clients connecting to the server a factor for this choice ? thanks

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  • Socket php server not showing messages sent from android client

    - by Mj1992
    Hi I am a newbie in these kind of stuff but here's what i want to do. I am trying to implement a chat application in which users will send their queries from the website and as soon as the messages are sent by the website users.It will appear in the android mobile application of the site owner who will answer their queries .In short I wanna implement a live chat. Now right now I am just simply trying to send messages from android app to php server. But when I run my php script from dreamweaver in chrome the browser keeps on loading and doesn't shows any output when I send message from the client. Sometimes it happened that the php script showed some outputs which I have sent from the android(client).But i don't know when it works and when it does not. So I want to show those messages in the php script as soon as I send those messages from client and vice versa(did not implemented the vice versa for client but help will be appreciated). Here's what I've done till now. php script: <?php set_time_limit (0); $address = '127.0.0.1'; $port = 1234; $sock = socket_create(AF_INET, SOCK_STREAM, 0); socket_bind($sock, $address, $port) or die('Could not bind to address'); socket_listen($sock); $client = socket_accept($sock); $welcome = "Roll up, roll up, to the greatest show on earth!\n? "; socket_write($client, $welcome,strlen($welcome)) or die("Could not send connect string\n"); do{ $input=socket_read($client,1024,1) or die("Could not read input\n"); echo "User Says: \n\t\t\t".$input; if (trim($input) != "") { echo "Received input: $input\n"; if(trim($input)=="END") { socket_close($spawn); break; } } else{ $output = strrev($input) . "\n"; socket_write($spawn, $output . "? ", strlen (($output)+2)) or die("Could not write output\n"); echo "Sent output: " . trim($output) . "\n"; } } while(true); socket_close($sock); echo "Socket Terminated"; ?> Android Code: public class ServerClientActivity extends Activity { private Button bt; private TextView tv; private Socket socket; private String serverIpAddress = "127.0.0.1"; private static final int REDIRECTED_SERVERPORT = 1234; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); bt = (Button) findViewById(R.id.myButton); tv = (TextView) findViewById(R.id.myTextView); try { InetAddress serverAddr = InetAddress.getByName(serverIpAddress); socket = new Socket(serverAddr, REDIRECTED_SERVERPORT); } catch (UnknownHostException e1) { e1.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } bt.setOnClickListener(new OnClickListener() { public void onClick(View v) { try { EditText et = (EditText) findViewById(R.id.EditText01); String str = et.getText().toString(); PrintWriter out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())),true); out.println(str); Log.d("Client", "Client sent message"); } catch (UnknownHostException e) { tv.setText(e.getMessage()); e.printStackTrace(); } catch (IOException e) { tv.setText(e.getMessage()); e.printStackTrace(); } catch (Exception e) { tv.setText(e.getMessage()); e.printStackTrace(); } } }); } } I've just pasted the onclick button event code for Android.Edit text is the textbox where I am going to enter my text. The ip address and port are same as in php script.

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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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  • C#: socket closing if user user exists

    - by corvallo
    Hi to everyone I'm trying to create a server/client application for a school project. This is the scenario: a server on a given port, multiple user connected, each user has it's own username. Now I want to check if a user that try to connect to the user use a valid username, for example if a user with username A it's already connected a new user that want to connect cannot use the username A. If this happen the server answer to the new client with an error code. This is the code for this part private void Receive() { while (true) { byte[] buffer = new byte[64]; socket.Receive(buffer); string received = Encoding.Default.GetString(buffer); if (received.IndexOf("!error") != -1) { string[] mySplit = received.Split(':'); string errorCode = mySplit[1].Trim((char)0); if (errorCode == "user exists") { richTextBox1.AppendText("Your connection was refused by server, because there's already another user connected with the username you choose"); socket.Disconnect(true); connectBtn.Enabled = true; } } } } But when I try to do this the program crash and visual studio said that there's an invalid cross-thread operation on richTextBox1. Any ideas. Thank you in advance.

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  • TCP/IP and UDP Questions and very small application for interview

    - by Shantanu Gupta
    I am going for an interview day after tomorrow where i will be asked vaious questions related to TCP/IP and UDP. As of now i have prepared theoritical knowledge about it. But now I am looking up for gaining some practicle knowledge related to how it works in a network. What all is going in vaious .NET classes. I want to create a very small application like a chat or something that can make me all these concepts very much clear. Could you please suggest some questions related to TCP/IP that you generally ask or that you might have faced. How communication is going from server to client. Right now I am studying TcpClient, TcpListener and UdpClient Class but I want to implement all of them so as to get aware about its working. Is Chat application a Tcp/IP application ? I would appreciate your help.

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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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  • How to write an Android SocketServer to listen on wifi

    - by xioxox
    I've written a thread using java.net.SocketServer to listen on a particular port. It works fine in the android simulator (using port forwarding). I'm planning to connect over wifi to this port when the app is being used. However, the SocketServer documentation says that if you don't supply an InetAddress, the server listens on localhost. Am I correct that if I do not supply the address, I will not be able to get a connection over wifi? How can I get the InetAddress of the wifi connection to pass to the SocketServer?

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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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  • Ruby TCPSocket doesn't notice it when server is killed

    - by user303308
    I've this ruby code that connects to a TCP server (namely, netcat). It loops 20 times, and sends "ABCD ". If I kill netcat, it takes TWO iterations of the loop for an exception to be triggered. On the first loop after netcat is killed, no exception is triggered, and "send" reports that 5 bytes have been correctly written... Which in the end is not true, since of course the server never received them. Is there a way to work around this issue ? Right now I'm losing data : since I think it's been correctly transfered, I'm not replaying it. #!/usr/bin/env ruby require 'rubygems' require 'socket' sock = TCPSocket.new('192.168.0.10', 5443) sock.sync = true 20.times do sleep 2 begin count = sock.write("ABCD ") puts "Wrote #{count} bytes" rescue Exception => myException puts "Exception rescued : #{myException}" end end

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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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  • How do I detect server status in a port scanner java implementation

    - by akz
    I am writing a port scanner in Java and I want to be able to distinct the following 4 use cases: port is open port is open and server banner was read port is closed server is not live I have the following code: InetAddress address = InetAddress.getByName("google.com"); int[] ports = new int[]{21, 22, 23, 80, 443}; for (int i = 0; i < ports.length; i++) { int port = ports[i]; Socket socket = null; try { socket = new Socket(address, port); socket.setSoTimeout(500); System.out.println("port " + port + " open"); BufferedReader reader = new BufferedReader( new InputStreamReader(socket.getInputStream())); String line = reader.readLine(); if (line != null) { System.out.println(line); } socket.close(); } catch (SocketTimeoutException ex) { // port was open but nothing was read from input stream ex.printStackTrace(); } catch (ConnectException ex) { // port is closed ex.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { if (socket != null && !socket.isClosed()) { try { socket.close(); } catch (Exception e) { e.printStackTrace(); } } } } The problem is that I get a ConnectionException both when the port is closed and the server cannot be reached but with a different exception message: java.net.ConnectException: Connection timed out: connect when the connection was never established and java.net.ConnectException: Connection refused: connect when the port was closed so I cannot make the distinction between the two use cases without digging into the actual exception message. Same thing happens when I try a different approach for the socket creation. If I use: socket = new Socket(); socket.setSoTimeout(500); socket.connect(new InetSocketAddress(address, port), 1000); I have the same problem but with the SocketTimeoutException instead. I get a java.net.SocketTimeoutException: Read timed out if port was open but there was no banner to be read and java.net.SocketTimeoutException: connect timed out if server is not live or port is closed. Any ideas? Thanks in advance!

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  • Asynchronous IO in Java?

    - by thr
    What options for async io (socket-based) are there in java other then java.nio? Also does java.nio use threads in the backround (as I think .NET's async-socket-library does, maybe it's been changed) or is it "true" async io using a proper select call?

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  • non blocking TCP-acceptor not reading from socket

    - by Abruzzo Forte e Gentile
    I have the code below implementing a NON-Blocking TCP acceptor. Clients are able to connect without any problem and the writing seems occurring as well, but the acceptor doesn't read anything from the socket and the call to read() blocks indefinitely. Am I using some wrong setting for the acceptor? Kind Regards AFG int main(){ create_programming_socket(); poll_programming_connect(); while(1){ poll_programming_read(); } } int create_programming_socket(){ int cnt = 0; p_listen_socket = socket( AF_INET, SOCK_STREAM, 0 ); if( p_listen_socket < 0 ){ return 1; } int flags = fcntl( p_listen_socket, F_GETFL, 0 ); if( fcntl( p_listen_socket, F_SETFL, flags | O_NONBLOCK ) == -1 ){ return 1; } bzero( (char*)&p_serv_addr, sizeof(p_serv_addr) ); p_serv_addr.sin_family = AF_INET; p_serv_addr.sin_addr.s_addr = INADDR_ANY; p_serv_addr.sin_port = htons( p_port ); if( bind( p_listen_socket, (struct sockaddr*)&p_serv_addr , sizeof(p_serv_addr) ) < 0 ) { return 1; } listen( p_listen_socket, 5 ); return 0; } int poll_programming_connect(){ int retval = 0; static socklen_t p_clilen = sizeof(p_cli_addr); int res = accept( p_listen_socket, (struct sockaddr*)&p_cli_addr, &p_clilen ); if( res > 0 ){ p_conn_socket = res; int flags = fcntl( p_conn_socket, F_GETFL, 0 ); if( fcntl( p_conn_socket, F_SETFL, flags | O_NONBLOCK ) == -1 ){ retval = 1; }else{ p_connected = true; } }else if( res == -1 && ( errno == EWOULDBLOCK || errno == EAGAIN ) ) { //printf( "poll_sock(): accept(c_listen_socket) would block\n"); }else{ retval = 1; } return retval; } int poll_programming_read(){ int retval = 0; bzero( p_buffer, 256 ); int numbytes = read( p_conn_socket, p_buffer, 255 ); if( numbytes > 0 ) { fprintf( stderr, "poll_sock(): read() read %d bytes\n", numbytes ); pkt_struct2_t tx_buf; int fred; int i; } else if( numbytes == -1 && ( errno == EWOULDBLOCK || errno == EAGAIN ) ) { //printf( "poll_sock(): read() would block\n"); } else { close( p_conn_socket ); p_connected = false; retval = 1; } return retval; }

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