JDK8/Java8源码在线阅读

/*
 * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */


package sun.security.ssl;

import java.io.OutputStream;
import java.io.IOException;

/*
 * Output stream for application data. This is the kind of stream
 * that's handed out via SSLSocket.getOutputStream(). It's all the application
 * ever sees.
 *
 * Once the initial handshake has completed, application data may be
 * interleaved with handshake data. That is handled internally and remains
 * transparent to the application.
 *
 * @author  David Brownell
 */
class AppOutputStream extends OutputStream {

    private SSLSocketImpl c;
    OutputRecord r;

    // One element array used to implement the write(byte) method
    private final byte[] oneByte = new byte[1];

    AppOutputStream(SSLSocketImpl conn) {
        r = new OutputRecord(Record.ct_application_data);
        c = conn;
    }

    /**
     * Write the data out, NOW.
     */
    @Override
    synchronized public void write(byte b[], int off, int len)
            throws IOException {
        if (b == null) {
            throw new NullPointerException();
        } else if (off < 0 || len < 0 || len > b.length - off) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return;
        }

        // check if the Socket is invalid (error or closed)
        c.checkWrite();

        /*
         * By default, we counter chosen plaintext issues on CBC mode
         * ciphersuites in SSLv3/TLS1.0 by sending one byte of application
         * data in the first record of every payload, and the rest in
         * subsequent record(s). Note that the issues have been solved in
         * TLS 1.1 or later.
         *
         * It is not necessary to split the very first application record of
         * a freshly negotiated TLS session, as there is no previous
         * application data to guess.  To improve compatibility, we will not
         * split such records.
         *
         * This avoids issues in the outbound direction.  For a full fix,
         * the peer must have similar protections.
         */
        boolean isFirstRecordOfThePayload = true;

        // Always flush at the end of each application level record.
        // This lets application synchronize read and write streams
        // however they like; if we buffered here, they couldn't.
        try {
            do {
                boolean holdRecord = false;
                int howmuch;
                if (isFirstRecordOfThePayload && c.needToSplitPayload()) {
                    howmuch = Math.min(0x01, r.availableDataBytes());
                     /*
                      * Nagle's algorithm (TCP_NODELAY) was coming into
                      * play here when writing short (split) packets.
                      * Signal to the OutputRecord code to internally
                      * buffer this small packet until the next outbound
                      * packet (of any type) is written.
                      */
                     if ((len != 1) && (howmuch == 1)) {
                         holdRecord = true;
                     }
                } else {
                    howmuch = Math.min(len, r.availableDataBytes());
                }

                if (isFirstRecordOfThePayload && howmuch != 0) {
                    isFirstRecordOfThePayload = false;
                }

                // NOTE: *must* call c.writeRecord() even for howmuch == 0
                if (howmuch > 0) {
                    r.write(b, off, howmuch);
                    off += howmuch;
                    len -= howmuch;
                }
                c.writeRecord(r, holdRecord);
                c.checkWrite();
            } while (len > 0);

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