connectbot/sshlib

package com.trilead.ssh2.crypto;
 
import java.io.IOException;
 
import java.math.BigInteger;
 
/**
 * SimpleDERReader.
 *
 * @author Christian Plattner, plattner@trilead.com
 * @version $Id: SimpleDERReader.java,v 1.1 2007/10/15 12:49:56 cplattne Exp $
 */
public class SimpleDERReader
{
    private static final int CONSTRUCTED = 0x20;
 
    byte[] buffer;
    int pos;
    int count;
 
    public SimpleDERReader(byte[] b)
    {
        resetInput(b);
    }
 
    public SimpleDERReader(byte[] b, int off, int len)
    {
        resetInput(b, off, len);
    }
 
    public void resetInput(byte[] b)
    {
        resetInput(b, 0, b.length);
    }
 
    public void resetInput(byte[] b, int off, int len)
    {
        buffer = b;
        pos = off;
        count = len;
    }
 
    private byte readByte() throws IOException
    {
        if (count <= 0)
            throw new IOException("DER byte array: out of data");
        count--;
        return buffer[pos++];
    }
 
    private byte[] readBytes(int len) throws IOException
    {
        if (len > count)
            throw new IOException("DER byte array: out of data");
 
        byte[] b = new byte[len];
 
        System.arraycopy(buffer, pos, b, 0, len);
 
        pos += len;
        count -= len;
 
        return b;
    }
 
    public int available()
    {
        return count;
    }
 
    /* visible for testing */
    int readLength() throws IOException
    {
        int len = readByte() & 0xff;
 
        if ((len & 0x80) == 0)
            return len;
 
        int remain = len & 0x7F;
 
        if (remain == 0)
            return -1;
        else if (remain > 4)
            return -1;
 
        len = 0;
 
        while (remain > 0)
        {
            len = len << 8;
            len = len | (readByte() & 0xff);
            remain--;
        }
 
        if (len < 0)
            return -1;
 
Avoid too many `return` statements within this method.
        return len;
    }
 
    public int ignoreNextObject() throws IOException
    {
        int type = readByte() & 0xff;
 
        int len = readLength();
 
        if ((len < 0) || len > available())
            throw new IOException("Illegal len in DER object (" + len  + ")");
 
        readBytes(len);
 
        return type;
    }
 
    public BigInteger readInt() throws IOException
    {
        int type = readByte() & 0xff;
 
        if (type != 0x02)
            throw new IOException("Expected DER Integer, but found type " + type);
 
        int len = readLength();
 
        if ((len < 0) || len > available())
            throw new IOException("Illegal len in DER object (" + len  + ")");
 
        byte[] b = readBytes(len);
 
        BigInteger bi = new BigInteger(1, b);
 
        return bi;
    }
 
    public int readConstructedType() throws IOException {
        int type = readByte() & 0xff;
 
        if ((type & CONSTRUCTED) != CONSTRUCTED)
            throw new IOException("Expected constructed type, but was " + type);
 
        return type & 0x1f;
    }
 
    public SimpleDERReader readConstructed() throws IOException
    {
        int len = readLength();
 
        if ((len < 0) || len > available())
            throw new IOException("Illegal len in DER object (" + len  + ")");
 
        SimpleDERReader cr = new SimpleDERReader(buffer, pos, len);
 
        pos += len;
        count -= len;
 
        return cr;
    }
 
    public byte[] readSequenceAsByteArray() throws IOException
    {
        int type = readByte() & 0xff;
 
        if (type != 0x30)
            throw new IOException("Expected DER Sequence, but found type " + type);
 
        int len = readLength();
 
        if ((len < 0) || len > available())
            throw new IOException("Illegal len in DER object (" + len  + ")");
 
        byte[] b = readBytes(len);
 
        return b;
    }
 
Method `readOid` has 31 lines of code (exceeds 25 allowed). Consider refactoring.
Method `readOid` has a Cognitive Complexity of 7 (exceeds 5 allowed). Consider refactoring.
    public String readOid() throws IOException
    {
        int type = readByte() & 0xff;
 
        if (type != 0x06)
            throw new IOException("Expected DER OID, but found type " + type);
 
        int len = readLength();
 
        if ((len < 1) || len > available())
            throw new IOException("Illegal len in DER object (" + len  + ")");
 
        byte[] b = readBytes(len);
 
        long value = 0;
 
        StringBuilder sb = new StringBuilder(64);
        switch (b[0] / 40) {
        case 0:
            sb.append('0');
            break;
        case 1:
            sb.append('1');
            b[0] -= 40;
            break;
        default:
            sb.append('2');
            b[0] -= 80;
            break;
        }
 
        for (int i = 0; i < len; i++) {
            value = (value << 7) + (b[i] & 0x7F);
            if ((b[i] & 0x80) == 0) {
                sb.append('.');
                sb.append(value);
                value = 0;
            }
        }
 
        return sb.toString();
    }
 
    public byte[] readOctetString() throws IOException
    {
        int type = readByte() & 0xff;
 
        if (type != 0x04 && type != 0x03)
            throw new IOException("Expected DER Octetstring, but found type " + type);
 
        int len = readLength();
 
        if ((len < 0) || len > available())
            throw new IOException("Illegal len in DER object (" + len  + ")");
 
        byte[] b = readBytes(len);
 
        return b;
    }
 
}