org.apache.commons.ssl.asn1.ASN1Sequence Maven / Gradle / Ivy

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package org.apache.commons.ssl.asn1;

import java.io.IOException;
import java.util.Enumeration;
import java.util.Vector;

public abstract class ASN1Sequence
    extends ASN1Object {
    private Vector seq = new Vector();

    /**
     * return an ASN1Sequence from the given object.
     *
     * @param obj the object we want converted.
     * @throws IllegalArgumentException if the object cannot be converted.
     */
    public static ASN1Sequence getInstance(
        Object obj) {
        if (obj == null || obj instanceof ASN1Sequence) {
            return (ASN1Sequence) obj;
        }

        throw new IllegalArgumentException("unknown object in getInstance");
    }

    /**
     * Return an ASN1 sequence from a tagged object. There is a special
     * case here, if an object appears to have been explicitly tagged on
     * reading but we were expecting it to be implictly tagged in the
     * normal course of events it indicates that we lost the surrounding
     * sequence - so we need to add it back (this will happen if the tagged
     * object is a sequence that contains other sequences). If you are
     * dealing with implicitly tagged sequences you really should
     * be using this method.
     *
     * @param obj      the tagged object.
     * @param explicit true if the object is meant to be explicitly tagged,
     *                 false otherwise.
     * @throws IllegalArgumentException if the tagged object cannot
     *                                  be converted.
     */
    public static ASN1Sequence getInstance(
        ASN1TaggedObject obj,
        boolean explicit) {
        if (explicit) {
            if (!obj.isExplicit()) {
                throw new IllegalArgumentException("object implicit - explicit expected.");
            }

            return (ASN1Sequence) obj.getObject();
        } else {
            //
            // constructed object which appears to be explicitly tagged
            // when it should be implicit means we have to add the
            // surrounding sequence.
            //
            if (obj.isExplicit()) {
                if (obj instanceof BERTaggedObject) {
                    return new BERSequence(obj.getObject());
                } else {
                    return new DERSequence(obj.getObject());
                }
            } else {
                if (obj.getObject() instanceof ASN1Sequence) {
                    return (ASN1Sequence) obj.getObject();
                }
            }
        }

        throw new IllegalArgumentException(
            "unknown object in getInstanceFromTagged");
    }

    public Enumeration getObjects() {
        return seq.elements();
    }

    public ASN1SequenceParser parser() {
        final ASN1Sequence outer = this;

        return new ASN1SequenceParser() {
            private final int max = size();

            private int index;

            public DEREncodable readObject() throws IOException {
                if (index == max) {
                    return null;
                }

                DEREncodable obj = getObjectAt(index++);
                if (obj instanceof ASN1Sequence) {
                    return ((ASN1Sequence) obj).parser();
                }
                if (obj instanceof ASN1Set) {
                    return ((ASN1Set) obj).parser();
                }

                return obj;
            }

            public DERObject getDERObject() {
                return outer;
            }
        };
    }

    /**
     * return the object at the sequence postion indicated by index.
     *
     * @param index the sequence number (starting at zero) of the object
     * @return the object at the sequence postion indicated by index.
     */
    public DEREncodable getObjectAt(
        int index) {
        return (DEREncodable) seq.elementAt(index);
    }

    /**
     * return the number of objects in this sequence.
     *
     * @return the number of objects in this sequence.
     */
    public int size() {
        return seq.size();
    }

    public int hashCode() {
        Enumeration e = this.getObjects();
        int hashCode = 0;

        while (e.hasMoreElements()) {
            Object o = e.nextElement();

            if (o != null) {
                hashCode ^= o.hashCode();
            }
        }

        return hashCode;
    }

    boolean asn1Equals(
        DERObject o) {
        if (!(o instanceof ASN1Sequence)) {
            return false;
        }

        ASN1Sequence other = (ASN1Sequence) o;

        if (this.size() != other.size()) {
            return false;
        }

        Enumeration s1 = this.getObjects();
        Enumeration s2 = other.getObjects();

        while (s1.hasMoreElements()) {
            DERObject o1 = ((DEREncodable) s1.nextElement()).getDERObject();
            DERObject o2 = ((DEREncodable) s2.nextElement()).getDERObject();

            if (o1 == o2 || (o1 != null && o1.equals(o2))) {
                continue;
            }

            return false;
        }

        return true;
    }

    protected void addObject(
        DEREncodable obj) {
        seq.addElement(obj);
    }

    abstract void encode(DEROutputStream out)
        throws IOException;

    public String toString() {
        return seq.toString();
    }
}