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1 /* |
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2 * Copyright (c) 2007, 2009, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 |
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26 package java.net; |
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27 |
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28 /** |
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29 * Defines the <em>standard</em> socket options. |
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30 * |
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31 * <p> The {@link SocketOption#name name} of each socket option defined by this |
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32 * class is its field name. |
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33 * |
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34 * <p> In this release, the socket options defined here are used by {@link |
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35 * java.nio.channels.NetworkChannel network} channels in the {@link |
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36 * java.nio.channels channels} package. |
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37 * |
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38 * @since 1.7 |
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39 */ |
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40 |
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41 public final class StandardSocketOptions { |
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42 private StandardSocketOptions() { } |
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43 |
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44 // -- SOL_SOCKET -- |
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45 |
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46 /** |
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47 * Allow transmission of broadcast datagrams. |
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48 * |
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49 * <p> The value of this socket option is a {@code Boolean} that represents |
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50 * whether the option is enabled or disabled. The option is specific to |
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51 * datagram-oriented sockets sending to {@link java.net.Inet4Address IPv4} |
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52 * broadcast addresses. When the socket option is enabled then the socket |
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53 * can be used to send <em>broadcast datagrams</em>. |
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54 * |
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55 * <p> The initial value of this socket option is {@code FALSE}. The socket |
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56 * option may be enabled or disabled at any time. Some operating systems may |
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57 * require that the Java virtual machine be started with implementation |
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58 * specific privileges to enable this option or send broadcast datagrams. |
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59 * |
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60 * @see <a href="http://www.ietf.org/rfc/rfc919.txt">RFC 929: |
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61 * Broadcasting Internet Datagrams</a> |
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62 * @see DatagramSocket#setBroadcast |
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63 */ |
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64 public static final SocketOption<Boolean> SO_BROADCAST = |
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65 new StdSocketOption<Boolean>("SO_BROADCAST", Boolean.class); |
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66 |
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67 /** |
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68 * Keep connection alive. |
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69 * |
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70 * <p> The value of this socket option is a {@code Boolean} that represents |
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71 * whether the option is enabled or disabled. When the {@code SO_KEEPALIVE} |
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72 * option is enabled the operating system may use a <em>keep-alive</em> |
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73 * mechanism to periodically probe the other end of a connection when the |
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74 * connection is otherwise idle. The exact semantics of the keep alive |
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75 * mechanism is system dependent and therefore unspecified. |
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76 * |
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77 * <p> The initial value of this socket option is {@code FALSE}. The socket |
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78 * option may be enabled or disabled at any time. |
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79 * |
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80 * @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122 |
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81 * Requirements for Internet Hosts -- Communication Layers</a> |
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82 * @see Socket#setKeepAlive |
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83 */ |
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84 public static final SocketOption<Boolean> SO_KEEPALIVE = |
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85 new StdSocketOption<Boolean>("SO_KEEPALIVE", Boolean.class); |
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86 |
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87 /** |
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88 * The size of the socket send buffer. |
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89 * |
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90 * <p> The value of this socket option is an {@code Integer} that is the |
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91 * size of the socket send buffer in bytes. The socket send buffer is an |
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92 * output buffer used by the networking implementation. It may need to be |
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93 * increased for high-volume connections. The value of the socket option is |
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94 * a <em>hint</em> to the implementation to size the buffer and the actual |
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95 * size may differ. The socket option can be queried to retrieve the actual |
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96 * size. |
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97 * |
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98 * <p> For datagram-oriented sockets, the size of the send buffer may limit |
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99 * the size of the datagrams that may be sent by the socket. Whether |
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100 * datagrams larger than the buffer size are sent or discarded is system |
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101 * dependent. |
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102 * |
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103 * <p> The initial/default size of the socket send buffer and the range of |
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104 * allowable values is system dependent although a negative size is not |
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105 * allowed. An attempt to set the socket send buffer to larger than its |
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106 * maximum size causes it to be set to its maximum size. |
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107 * |
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108 * <p> An implementation allows this socket option to be set before the |
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109 * socket is bound or connected. Whether an implementation allows the |
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110 * socket send buffer to be changed after the socket is bound is system |
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111 * dependent. |
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112 * |
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113 * @see Socket#setSendBufferSize |
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114 */ |
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115 public static final SocketOption<Integer> SO_SNDBUF = |
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116 new StdSocketOption<Integer>("SO_SNDBUF", Integer.class); |
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117 |
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118 |
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119 /** |
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120 * The size of the socket receive buffer. |
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121 * |
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122 * <p> The value of this socket option is an {@code Integer} that is the |
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123 * size of the socket receive buffer in bytes. The socket receive buffer is |
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124 * an input buffer used by the networking implementation. It may need to be |
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125 * increased for high-volume connections or decreased to limit the possible |
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126 * backlog of incoming data. The value of the socket option is a |
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127 * <em>hint</em> to the implementation to size the buffer and the actual |
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128 * size may differ. |
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129 * |
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130 * <p> For datagram-oriented sockets, the size of the receive buffer may |
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131 * limit the size of the datagrams that can be received. Whether datagrams |
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132 * larger than the buffer size can be received is system dependent. |
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133 * Increasing the socket receive buffer may be important for cases where |
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134 * datagrams arrive in bursts faster than they can be processed. |
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135 * |
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136 * <p> In the case of stream-oriented sockets and the TCP/IP protocol, the |
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137 * size of the socket receive buffer may be used when advertising the size |
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138 * of the TCP receive window to the remote peer. |
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139 * |
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140 * <p> The initial/default size of the socket receive buffer and the range |
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141 * of allowable values is system dependent although a negative size is not |
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142 * allowed. An attempt to set the socket receive buffer to larger than its |
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143 * maximum size causes it to be set to its maximum size. |
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144 * |
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145 * <p> An implementation allows this socket option to be set before the |
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146 * socket is bound or connected. Whether an implementation allows the |
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147 * socket receive buffer to be changed after the socket is bound is system |
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148 * dependent. |
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149 * |
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150 * @see <a href="http://www.ietf.org/rfc/rfc1323.txt">RFC 1323: TCP |
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151 * Extensions for High Performance</a> |
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152 * @see Socket#setReceiveBufferSize |
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153 * @see ServerSocket#setReceiveBufferSize |
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154 */ |
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155 public static final SocketOption<Integer> SO_RCVBUF = |
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156 new StdSocketOption<Integer>("SO_RCVBUF", Integer.class); |
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157 |
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158 /** |
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159 * Re-use address. |
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160 * |
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161 * <p> The value of this socket option is a {@code Boolean} that represents |
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162 * whether the option is enabled or disabled. The exact semantics of this |
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163 * socket option are socket type and system dependent. |
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164 * |
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165 * <p> In the case of stream-oriented sockets, this socket option will |
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166 * usually determine whether the socket can be bound to a socket address |
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167 * when a previous connection involving that socket address is in the |
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168 * <em>TIME_WAIT</em> state. On implementations where the semantics differ, |
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169 * and the socket option is not required to be enabled in order to bind the |
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170 * socket when a previous connection is in this state, then the |
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171 * implementation may choose to ignore this option. |
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172 * |
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173 * <p> For datagram-oriented sockets the socket option is used to allow |
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174 * multiple programs bind to the same address. This option should be enabled |
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175 * when the socket is to be used for Internet Protocol (IP) multicasting. |
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176 * |
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177 * <p> An implementation allows this socket option to be set before the |
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178 * socket is bound or connected. Changing the value of this socket option |
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179 * after the socket is bound has no effect. The default value of this |
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180 * socket option is system dependent. |
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181 * |
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182 * @see <a href="http://www.ietf.org/rfc/rfc793.txt">RFC 793: Transmission |
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183 * Control Protocol</a> |
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184 * @see ServerSocket#setReuseAddress |
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185 */ |
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186 public static final SocketOption<Boolean> SO_REUSEADDR = |
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187 new StdSocketOption<Boolean>("SO_REUSEADDR", Boolean.class); |
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188 |
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189 /** |
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190 * Linger on close if data is present. |
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191 * |
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192 * <p> The value of this socket option is an {@code Integer} that controls |
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193 * the action taken when unsent data is queued on the socket and a method |
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194 * to close the socket is invoked. If the value of the socket option is zero |
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195 * or greater, then it represents a timeout value, in seconds, known as the |
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196 * <em>linger interval</em>. The linger interval is the timeout for the |
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197 * {@code close} method to block while the operating system attempts to |
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198 * transmit the unsent data or it decides that it is unable to transmit the |
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199 * data. If the value of the socket option is less than zero then the option |
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200 * is disabled. In that case the {@code close} method does not wait until |
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201 * unsent data is transmitted; if possible the operating system will transmit |
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202 * any unsent data before the connection is closed. |
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203 * |
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204 * <p> This socket option is intended for use with sockets that are configured |
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205 * in {@link java.nio.channels.SelectableChannel#isBlocking() blocking} mode |
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206 * only. The behavior of the {@code close} method when this option is |
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207 * enabled on a non-blocking socket is not defined. |
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208 * |
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209 * <p> The initial value of this socket option is a negative value, meaning |
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210 * that the option is disabled. The option may be enabled, or the linger |
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211 * interval changed, at any time. The maximum value of the linger interval |
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212 * is system dependent. Setting the linger interval to a value that is |
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213 * greater than its maximum value causes the linger interval to be set to |
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214 * its maximum value. |
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215 * |
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216 * @see Socket#setSoLinger |
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217 */ |
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218 public static final SocketOption<Integer> SO_LINGER = |
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219 new StdSocketOption<Integer>("SO_LINGER", Integer.class); |
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220 |
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221 |
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222 // -- IPPROTO_IP -- |
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223 |
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224 /** |
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225 * The Type of Service (ToS) octet in the Internet Protocol (IP) header. |
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226 * |
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227 * <p> The value of this socket option is an {@code Integer} representing |
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228 * the value of the ToS octet in IP packets sent by sockets to an {@link |
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229 * StandardProtocolFamily#INET IPv4} socket. The interpretation of the ToS |
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230 * octet is network specific and is not defined by this class. Further |
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231 * information on the ToS octet can be found in <a |
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232 * href="http://www.ietf.org/rfc/rfc1349.txt">RFC 1349</a> and <a |
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233 * href="http://www.ietf.org/rfc/rfc2474.txt">RFC 2474</a>. The value |
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234 * of the socket option is a <em>hint</em>. An implementation may ignore the |
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235 * value, or ignore specific values. |
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236 * |
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237 * <p> The initial/default value of the TOS field in the ToS octet is |
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238 * implementation specific but will typically be {@code 0}. For |
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239 * datagram-oriented sockets the option may be configured at any time after |
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240 * the socket has been bound. The new value of the octet is used when sending |
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241 * subsequent datagrams. It is system dependent whether this option can be |
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242 * queried or changed prior to binding the socket. |
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243 * |
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244 * <p> The behavior of this socket option on a stream-oriented socket, or an |
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245 * {@link StandardProtocolFamily#INET6 IPv6} socket, is not defined in this |
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246 * release. |
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247 * |
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248 * @see DatagramSocket#setTrafficClass |
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249 */ |
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250 public static final SocketOption<Integer> IP_TOS = |
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251 new StdSocketOption<Integer>("IP_TOS", Integer.class); |
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252 |
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253 /** |
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254 * The network interface for Internet Protocol (IP) multicast datagrams. |
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255 * |
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256 * <p> The value of this socket option is a {@link NetworkInterface} that |
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257 * represents the outgoing interface for multicast datagrams sent by the |
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258 * datagram-oriented socket. For {@link StandardProtocolFamily#INET6 IPv6} |
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259 * sockets then it is system dependent whether setting this option also |
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260 * sets the outgoing interface for multlicast datagrams sent to IPv4 |
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261 * addresses. |
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262 * |
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263 * <p> The initial/default value of this socket option may be {@code null} |
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264 * to indicate that outgoing interface will be selected by the operating |
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265 * system, typically based on the network routing tables. An implementation |
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266 * allows this socket option to be set after the socket is bound. Whether |
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267 * the socket option can be queried or changed prior to binding the socket |
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268 * is system dependent. |
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269 * |
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270 * @see java.nio.channels.MulticastChannel |
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271 * @see MulticastSocket#setInterface |
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272 */ |
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273 public static final SocketOption<NetworkInterface> IP_MULTICAST_IF = |
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274 new StdSocketOption<NetworkInterface>("IP_MULTICAST_IF", NetworkInterface.class); |
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275 |
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276 /** |
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277 * The <em>time-to-live</em> for Internet Protocol (IP) multicast datagrams. |
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278 * |
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279 * <p> The value of this socket option is an {@code Integer} in the range |
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280 * <tt>0 <= value <= 255</tt>. It is used to control |
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281 * the scope of multicast datagrams sent by the datagram-oriented socket. |
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282 * In the case of an {@link StandardProtocolFamily#INET IPv4} socket |
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283 * the option is the time-to-live (TTL) on multicast datagrams sent by the |
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284 * socket. Datagrams with a TTL of zero are not transmitted on the network |
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285 * but may be delivered locally. In the case of an {@link |
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286 * StandardProtocolFamily#INET6 IPv6} socket the option is the |
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287 * <em>hop limit</em> which is number of <em>hops</em> that the datagram can |
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288 * pass through before expiring on the network. For IPv6 sockets it is |
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289 * system dependent whether the option also sets the <em>time-to-live</em> |
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290 * on multicast datagrams sent to IPv4 addresses. |
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291 * |
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292 * <p> The initial/default value of the time-to-live setting is typically |
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293 * {@code 1}. An implementation allows this socket option to be set after |
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294 * the socket is bound. Whether the socket option can be queried or changed |
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295 * prior to binding the socket is system dependent. |
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296 * |
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297 * @see java.nio.channels.MulticastChannel |
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298 * @see MulticastSocket#setTimeToLive |
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299 */ |
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300 public static final SocketOption<Integer> IP_MULTICAST_TTL = |
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301 new StdSocketOption<Integer>("IP_MULTICAST_TTL", Integer.class); |
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302 |
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303 /** |
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304 * Loopback for Internet Protocol (IP) multicast datagrams. |
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305 * |
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306 * <p> The value of this socket option is a {@code Boolean} that controls |
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307 * the <em>loopback</em> of multicast datagrams. The value of the socket |
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308 * option represents if the option is enabled or disabled. |
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309 * |
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310 * <p> The exact semantics of this socket options are system dependent. |
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311 * In particular, it is system dependent whether the loopback applies to |
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312 * multicast datagrams sent from the socket or received by the socket. |
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313 * For {@link StandardProtocolFamily#INET6 IPv6} sockets then it is |
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314 * system dependent whether the option also applies to multicast datagrams |
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315 * sent to IPv4 addresses. |
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316 * |
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317 * <p> The initial/default value of this socket option is {@code TRUE}. An |
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318 * implementation allows this socket option to be set after the socket is |
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319 * bound. Whether the socket option can be queried or changed prior to |
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320 * binding the socket is system dependent. |
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321 * |
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322 * @see java.nio.channels.MulticastChannel |
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323 * @see MulticastSocket#setLoopbackMode |
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324 */ |
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325 public static final SocketOption<Boolean> IP_MULTICAST_LOOP = |
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326 new StdSocketOption<Boolean>("IP_MULTICAST_LOOP", Boolean.class); |
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327 |
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328 |
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329 // -- IPPROTO_TCP -- |
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330 |
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331 /** |
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332 * Disable the Nagle algorithm. |
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333 * |
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334 * <p> The value of this socket option is a {@code Boolean} that represents |
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335 * whether the option is enabled or disabled. The socket option is specific to |
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336 * stream-oriented sockets using the TCP/IP protocol. TCP/IP uses an algorithm |
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337 * known as <em>The Nagle Algorithm</em> to coalesce short segments and |
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338 * improve network efficiency. |
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339 * |
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340 * <p> The default value of this socket option is {@code FALSE}. The |
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341 * socket option should only be enabled in cases where it is known that the |
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342 * coalescing impacts performance. The socket option may be enabled at any |
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343 * time. In other words, the Nagle Algorithm can be disabled. Once the option |
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344 * is enabled, it is system dependent whether it can be subsequently |
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345 * disabled. If it cannot, then invoking the {@code setOption} method to |
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346 * disable the option has no effect. |
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347 * |
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348 * @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122: |
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349 * Requirements for Internet Hosts -- Communication Layers</a> |
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350 * @see Socket#setTcpNoDelay |
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351 */ |
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352 public static final SocketOption<Boolean> TCP_NODELAY = |
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353 new StdSocketOption<Boolean>("TCP_NODELAY", Boolean.class); |
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354 |
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355 |
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356 private static class StdSocketOption<T> implements SocketOption<T> { |
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357 private final String name; |
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358 private final Class<T> type; |
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359 StdSocketOption(String name, Class<T> type) { |
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360 this.name = name; |
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361 this.type = type; |
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362 } |
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363 @Override public String name() { return name; } |
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364 @Override public Class<T> type() { return type; } |
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365 @Override public String toString() { return name; } |
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366 } |
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367 } |