DERGenerator.java

package org.apache.commons.ssl.asn1;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public abstract class DERGenerator
    extends ASN1Generator {
    private boolean _tagged = false;
    private boolean _isExplicit;
    private int _tagNo;

    protected DERGenerator(
        OutputStream out) {
        super(out);
    }

    public DERGenerator(
        OutputStream out,
        int tagNo,
        boolean isExplicit) {
        super(out);

        _tagged = true;
        _isExplicit = isExplicit;
        _tagNo = tagNo;
    }

    private void writeLength(
        OutputStream out,
        int length)
        throws IOException {
        if (length > 127) {
            int size = 1;
            int val = length;

            while ((val >>>= 8) != 0) {
                size++;
            }

            out.write((byte) (size | 0x80));

            for (int i = (size - 1) * 8; i >= 0; i -= 8) {
                out.write((byte) (length >> i));
            }
        } else {
            out.write((byte) length);
        }
    }

    void writeDEREncoded(
        OutputStream out,
        int tag,
        byte[] bytes)
        throws IOException {
        out.write(tag);
        writeLength(out, bytes.length);
        out.write(bytes);
    }

    void writeDEREncoded(
        int tag,
        byte[] bytes)
        throws IOException {
        if (_tagged) {
            int tagNum = _tagNo | DERTags.TAGGED;

            if (_isExplicit) {
                int newTag = _tagNo | DERTags.CONSTRUCTED | DERTags.TAGGED;

                ByteArrayOutputStream bOut = new ByteArrayOutputStream();

                writeDEREncoded(bOut, tag, bytes);

                writeDEREncoded(_out, newTag, bOut.toByteArray());
            } else {
                if ((tag & DERTags.CONSTRUCTED) != 0) {
                    writeDEREncoded(_out, tagNum | DERTags.CONSTRUCTED, bytes);
                } else {
                    writeDEREncoded(_out, tagNum, bytes);
                }
            }
        } else {
            writeDEREncoded(_out, tag, bytes);
        }
    }

    void writeDEREncoded(
        OutputStream out,
        int tag,
        InputStream in)
        throws IOException {
        out.write(tag);

        ByteArrayOutputStream bOut = new ByteArrayOutputStream();

        int b = 0;
        while ((b = in.read()) >= 0) {
            bOut.write(b);
        }

        byte[] bytes = bOut.toByteArray();

        writeLength(out, bytes.length);
        out.write(bytes);
    }
}