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package sun.security.ssl;

import java.util.*;

A list of ProtocolVersions. Also maintains the list of supported protocols.
Instances of this class are immutable. Some member variables are final
and can be accessed directly without method accessors.
Author:
 Andreas Sterbenz
Since:
  1.4.1/**
 * A list of ProtocolVersions. Also maintains the list of supported protocols.
 * Instances of this class are immutable. Some member variables are final
 * and can be accessed directly without method accessors.
 *
 * @author  Andreas Sterbenz
 * @since   1.4.1
 */
final class ProtocolList {

    // the sorted protocol version list
    private final ArrayList<ProtocolVersion> protocols;

    private String[] protocolNames;

    // the minimum and maximum ProtocolVersions in this list
    final ProtocolVersion min, max;

    // the format for the hello version to use
    final ProtocolVersion helloVersion;

    ProtocolList(String[] names) {
        this(convert(names));
    }

    ProtocolList(ArrayList<ProtocolVersion> versions) {
        this.protocols = versions;

        if ((protocols.size() == 1) &&
                protocols.contains(ProtocolVersion.SSL20Hello)) {
            throw new IllegalArgumentException("SSLv2Hello cannot be " +
                "enabled unless at least one other supported version " +
                "is also enabled.");
        }

        if (protocols.size() != 0) {
            Collections.sort(protocols);
            min = protocols.get(0);
            max = protocols.get(protocols.size() - 1);
            helloVersion = protocols.get(0);
        } else {
            min = ProtocolVersion.NONE;
            max = ProtocolVersion.NONE;
            helloVersion = ProtocolVersion.NONE;
        }
    }

    private static ArrayList<ProtocolVersion> convert(String[] names) {
        if (names == null) {
            throw new IllegalArgumentException("Protocols may not be null");
        }

        ArrayList<ProtocolVersion> versions = new ArrayList<>(names.length);
        for (int i = 0; i < names.length; i++ ) {
            ProtocolVersion version = ProtocolVersion.valueOf(names[i]);
            if (versions.contains(version) == false) {
                versions.add(version);
            }
        }

        return versions;
    }

    
Return whether this list contains the specified protocol version.
SSLv2Hello is not a real protocol version we support, we always
return false for it.
/**
     * Return whether this list contains the specified protocol version.
     * SSLv2Hello is not a real protocol version we support, we always
     * return false for it.
     */
    boolean contains(ProtocolVersion protocolVersion) {
        if (protocolVersion == ProtocolVersion.SSL20Hello) {
            return false;
        }
        return protocols.contains(protocolVersion);
    }

    
Return a reference to the internal Collection of CipherSuites.
The Collection MUST NOT be modified.
/**
     * Return a reference to the internal Collection of CipherSuites.
     * The Collection MUST NOT be modified.
     */
    Collection<ProtocolVersion> collection() {
        return protocols;
    }

    
Select a protocol version from the list.
Return the lower of the protocol version of that suggested by
the protocolVersion and the highest version of this
protocol list, or null if no protocol version is available.
The method is used by TLS server to negotiated the protocol
version between client suggested protocol version in the
client hello and protocol versions supported by the server.
/**
     * Select a protocol version from the list.
     *
     * Return the lower of the protocol version of that suggested by
     * the <code>protocolVersion</code> and the highest version of this
     * protocol list, or null if no protocol version is available.
     *
     * The method is used by TLS server to negotiated the protocol
     * version between client suggested protocol version in the
     * client hello and protocol versions supported by the server.
     */
    ProtocolVersion selectProtocolVersion(ProtocolVersion protocolVersion) {
        ProtocolVersion selectedVersion = null;
        for (ProtocolVersion pv : protocols) {
            if (pv.compareTo(protocolVersion) > 0) {
                break;      // Safe to break here as this.protocols is sorted,
                            // and DTLS and SSL/TLS protocols are not mixed.
            }
            selectedVersion = pv;
        }

        return selectedVersion;
    }

    
Return an array with the names of the ProtocolVersions in this list.
/**
     * Return an array with the names of the ProtocolVersions in this list.
     */
    synchronized String[] toStringArray() {
        if (protocolNames == null) {
            protocolNames = new String[protocols.size()];
            int i = 0;
            for (ProtocolVersion version : protocols) {
                protocolNames[i++] = version.name;
            }
        }
        return protocolNames.clone();
    }

    @Override
    public String toString() {
        return protocols.toString();
    }
}