[18987] | 1 | package org.greenstone.gatherer.util;
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| 2 |
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| 3 | /** Verbatim copy of what's in GS3's org.greenstone.server */
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| 4 |
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| 5 | import java.io.IOException;
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| 6 | import java.net.ServerSocket;
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| 7 | import java.net.BindException;
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| 8 |
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| 9 | // When needing to use sockets, this class can be used to find an available port
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| 10 | public class PortFinder {
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| 11 |
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| 12 | // Port numbers range from 0 to 65,535. RESERVED PORTS are below 1025
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| 13 | // see http://www.gnu.org/software/hello/manual/libc/Ports.html
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| 14 | public static final int MAX_PORT = 65535;
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| 15 | public static final int PORTS_RESERVED = 1024;
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| 16 |
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| 17 | // Considering a limited range of ports that will be reused (circular buffer)
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| 18 | public final int PORT_BASE;
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| 19 | public final int PORT_BLOCK_SIZE;
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| 20 |
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| 21 | // Keep track of what port numbers we have checked for availability
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| 22 | private int nextFreePort;
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| 23 |
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| 24 | // The socket port number that we will use
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| 25 | private int port = -1;
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| 26 |
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| 27 |
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| 28 | public PortFinder() {
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| 29 | this( PORTS_RESERVED+1, (MAX_PORT - PORTS_RESERVED) );
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| 30 | }
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| 31 |
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| 32 | public PortFinder(int base, int blocksize) {
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| 33 | PORT_BASE = base;
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| 34 | PORT_BLOCK_SIZE = blocksize;
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| 35 |
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| 36 | nextFreePort = PORT_BASE;
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| 37 | }
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| 38 |
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| 39 | /** Circular buffer. Modifies the value of nextFreePort (the buffer index). */
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| 40 | private void incrementNextFreePort() {
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| 41 | int offset = nextFreePort - PORT_BASE;
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| 42 | offset = (offset + 1) % PORT_BLOCK_SIZE;
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| 43 | nextFreePort = PORT_BASE + offset;
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| 44 | }
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| 45 |
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| 46 | /** Finds the first available port in the range specified during Constructor call.
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| 47 | * @return the number of an available port.
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| 48 | */
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| 49 | public int findPortInRange() throws Exception {
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| 50 | try {
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| 51 | boolean foundFreePort = false;
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| 52 | for(int i = 0; i < PORT_BLOCK_SIZE; i++) {
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| 53 |
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| 54 | if(isPortAvailable(nextFreePort)) {
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| 55 | foundFreePort = true;
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| 56 | break;
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| 57 |
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| 58 | } else {
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| 59 | incrementNextFreePort();
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| 60 | }
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| 61 | }
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| 62 |
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| 63 | if(foundFreePort) {
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| 64 | // Free port number currently found becomes the port number of the socket
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| 65 | // that will be used
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| 66 | this.port = nextFreePort;
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| 67 | incrementNextFreePort();
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| 68 |
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| 69 | } else {
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| 70 | throw new Exception("Cannot find an available port in the range "
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[18991] | 71 | + PORT_BASE + "-" + (PORT_BASE+PORT_BLOCK_SIZE));
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[18987] | 72 | }
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| 73 |
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[18991] | 74 | } catch(IOException e) {
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[18987] | 75 | System.err.println("Error when trying to find an available port. In PortFinder.findPort() " + e);
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| 76 | }
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| 77 | return port;
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| 78 | }
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| 79 |
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| 80 | /** @return true if the portnumber is in the valid range. */
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| 81 | public static boolean isValidPortNumber(int portNum) {
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| 82 | return (portNum >= 0 && portNum <= MAX_PORT);
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| 83 | }
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| 84 |
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| 85 | /** @return true if the portnumber is in the useable range. */
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| 86 | public static boolean isAssignablePortNumber(int portNum) {
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| 87 | return (portNum > PORTS_RESERVED && portNum <= MAX_PORT);
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| 88 | }
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| 89 |
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| 90 | /** Finds an available port.
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| 91 | * @return the number of an available port.
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| 92 | */
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| 93 | public static int findAnyFreePort() throws Exception {
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| 94 | ServerSocket tmpSocket = null;
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| 95 | int portNumber = -1;
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| 96 | try {
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| 97 | // Creates a server socket, bound to the specified port.
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| 98 | // A port of 0 creates a socket on any free port.
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| 99 | tmpSocket = new ServerSocket(0);
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| 100 | portNumber = tmpSocket.getLocalPort();
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| 101 | tmpSocket.close();
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| 102 | } catch(Exception e) {
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| 103 | System.err.println("Unable to find a free port or close it. Got Exception: " + e);
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| 104 | tmpSocket = null;
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| 105 | }
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| 106 | return portNumber;
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| 107 | }
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| 108 |
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| 109 | /** @return true if the portnum is available for use */
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| 110 | public static boolean isPortAvailable(int portnum) {
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| 111 | ServerSocket tmpSocket = null;
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| 112 | try {
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| 113 | tmpSocket = new ServerSocket(portnum);
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| 114 | tmpSocket.close();
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| 115 | //System.err.println("Port " + portnum + " not yet in use.");
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| 116 | return true;
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| 117 |
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| 118 | } catch(BindException ex){
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| 119 | // "Signals that an error occurred while attempting to bind a
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| 120 | // socket to a local address and port. Typically, the port is
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| 121 | // in use, or the requested local address could not be assigned."
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| 122 | System.err.println("Port " + portnum + " already in use or can't be assigned.");
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| 123 | tmpSocket = null;
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| 124 | return false;
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| 125 | } catch(Exception ex) {
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| 126 | // Some other problem creating or closing the server socket
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| 127 | System.err.println("Problem creating or closing server socket at port " + portnum);
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| 128 | tmpSocket = null;
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| 129 | return false;
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| 130 | }
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| 131 | }
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| 132 | } |
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