mail.mime.base64.ignoreerrors
+ * controls whether errors in the encoded data cause an exception
+ * or are ignored. The default is false (errors cause exception).
+ *
+ * @param in the input stream
+ */
+ public BASE64DecoderStream(InputStream in) {
+ super(in);
+ // default to false
+ ignoreErrors = PropUtil.getBooleanSystemProperty(
+ "mail.mime.base64.ignoreerrors", false);
+ }
+
+ /**
+ * Create a BASE64 decoder that decodes the specified input stream.
+ *
+ * @param in the input stream
+ * @param ignoreErrors ignore errors in encoded data?
+ */
+ public BASE64DecoderStream(InputStream in, boolean ignoreErrors) {
+ super(in);
+ this.ignoreErrors = ignoreErrors;
+ }
+
+ /**
+ * Read the next decoded byte from this input stream. The byte
+ * is returned as an int in the range 0
+ * to 255. If no byte is available because the end of
+ * the stream has been reached, the value -1 is returned.
+ * This method blocks until input data is available, the end of the
+ * stream is detected, or an exception is thrown.
+ *
+ * @return next byte of data, or -1 if the end of the
+ * stream is reached.
+ * @exception IOException if an I/O error occurs.
+ * @see java.io.FilterInputStream#in
+ */
+ @Override
+ public int read() throws IOException {
+ if (index >= bufsize) {
+ bufsize = decode(buffer, 0, buffer.length);
+ if (bufsize <= 0) {
+ return -1;
+ }
+ index = 0; // reset index into buffer
+ }
+ return buffer[index++] & 0xff; // Zero off the MSB
+ }
+
+ /**
+ * Reads up to len decoded bytes of data from this input stream
+ * into an array of bytes. This method blocks until some input is
+ * available.
+ *
+ *
+ * @param buf the buffer into which the data is read.
+ * @param off the start offset of the data.
+ * @param len the maximum number of bytes read.
+ * @return the total number of bytes read into the buffer, or
+ * -1 if there is no more data because the end of
+ * the stream has been reached.
+ * @exception IOException if an I/O error occurs.
+ */
+ @Override
+ public int read(byte[] buf, int off, int len) throws IOException {
+ // empty out single byte read buffer
+ int off0 = off;
+ while (index < bufsize && len > 0) {
+ buf[off++] = buffer[index++];
+ len--;
+ }
+ if (index >= bufsize) {
+ bufsize = index = 0;
+ }
+
+ int bsize = (len / 3) * 3; // round down to multiple of 3 bytes
+ if (bsize > 0) {
+ int size = decode(buf, off, bsize);
+ off += size;
+ len -= size;
+
+ if (size != bsize) { // hit EOF?
+ if (off == off0) {
+ return -1;
+ } else {
+ return off - off0;
+ }
+ }
+ }
+
+ // finish up with a partial read if necessary
+ for (; len > 0; len--) {
+ int c = read();
+ if (c == -1) {
+ break;
+ }
+ buf[off++] = (byte)c;
+ }
+
+ if (off == off0) {
+ return -1;
+ } else {
+ return off - off0;
+ }
+ }
+
+ /**
+ * Skips over and discards n bytes of data from this stream.
+ */
+ @Override
+ public long skip(long n) throws IOException {
+ long skipped = 0;
+ while (n-- > 0 && read() >= 0) {
+ skipped++;
+ }
+ return skipped;
+ }
+
+ /**
+ * Tests if this input stream supports marks. Currently this class
+ * does not support marks
+ */
+ @Override
+ public boolean markSupported() {
+ return false; // Maybe later ..
+ }
+
+ /**
+ * Returns the number of bytes that can be read from this input
+ * stream without blocking. However, this figure is only
+ * a close approximation in case the original encoded stream
+ * contains embedded CRLFs; since the CRLFs are discarded, not decoded
+ */
+ @Override
+ public int available() throws IOException {
+ // This is only an estimate, since in.available()
+ // might include CRLFs too ..
+ return ((in.available() * 3)/4 + (bufsize-index));
+ }
+
+ /**
+ * This character array provides the character to value map
+ * based on RFC1521.
+ */
+ private final static char pem_array[] = {
+ 'A','B','C','D','E','F','G','H', // 0
+ 'I','J','K','L','M','N','O','P', // 1
+ 'Q','R','S','T','U','V','W','X', // 2
+ 'Y','Z','a','b','c','d','e','f', // 3
+ 'g','h','i','j','k','l','m','n', // 4
+ 'o','p','q','r','s','t','u','v', // 5
+ 'w','x','y','z','0','1','2','3', // 6
+ '4','5','6','7','8','9','+','/' // 7
+ };
+
+ private final static byte pem_convert_array[] = new byte[256];
+
+ static {
+ for (int i = 0; i < 255; i++) {
+ pem_convert_array[i] = -1;
+ }
+ for (int i = 0; i < pem_array.length; i++) {
+ pem_convert_array[pem_array[i]] = (byte)i;
+ }
+ }
+
+ /**
+ * The decoder algorithm. Most of the complexity here is dealing
+ * with error cases. Returns the number of bytes decoded, which
+ * may be zero. Decoding is done by filling an int with 4 6-bit
+ * values by shifting them in from the bottom and then extracting
+ * 3 8-bit bytes from the int by shifting them out from the bottom.
+ *
+ * @param outbuf the buffer into which to put the decoded bytes
+ * @param pos position in the buffer to start filling
+ * @param len the number of bytes to fill
+ * @return the number of bytes filled, always a multiple
+ * of three, and may be zero
+ * @exception IOException if the data is incorrectly formatted
+ */
+ private int decode(byte[] outbuf, int pos, int len) throws IOException {
+ int pos0 = pos;
+ while (len >= 3) {
+ /*
+ * We need 4 valid base64 characters before we start decoding.
+ * We skip anything that's not a valid base64 character (usually
+ * just CRLF).
+ */
+ int got = 0;
+ int val = 0;
+ while (got < 4) {
+ int i = getByte();
+ if (i == -1 || i == -2) {
+ boolean atEOF;
+ if (i == -1) {
+ if (got == 0) {
+ return pos - pos0;
+ }
+ if (!ignoreErrors) {
+ throw new DecodingException(
+ "BASE64Decoder: Error in encoded stream: " +
+ "needed 4 valid base64 characters " +
+ "but only got " + got + " before EOF" +
+ recentChars());
+ }
+ atEOF = true; // don't read any more
+ } else { // i == -2
+ // found a padding character, we're at EOF
+ // XXX - should do something to make EOF "sticky"
+ if (got < 2 && !ignoreErrors) {
+ throw new DecodingException(
+ "BASE64Decoder: Error in encoded stream: " +
+ "needed at least 2 valid base64 characters," +
+ " but only got " + got +
+ " before padding character (=)" +
+ recentChars());
+ }
+
+ // didn't get any characters before padding character?
+ if (got == 0) {
+ return pos - pos0;
+ }
+ atEOF = false; // need to keep reading
+ }
+
+ // pad partial result with zeroes
+
+ // how many bytes will we produce on output?
+ // (got always < 4, so size always < 3)
+ int size = got - 1;
+ if (size == 0) {
+ size = 1;
+ }
+
+ // handle the one padding character we've seen
+ got++;
+ val <<= 6;
+
+ while (got < 4) {
+ if (!atEOF) {
+ // consume the rest of the padding characters,
+ // filling with zeroes
+ i = getByte();
+ if (i == -1) {
+ if (!ignoreErrors) {
+ throw new DecodingException(
+ "BASE64Decoder: Error in encoded " +
+ "stream: hit EOF while looking for " +
+ "padding characters (=)" +
+ recentChars());
+ }
+ } else if (i != -2) {
+ if (!ignoreErrors) {
+ throw new DecodingException(
+ "BASE64Decoder: Error in encoded " +
+ "stream: found valid base64 " +
+ "character after a padding character " +
+ "(=)" + recentChars());
+ }
+ }
+ }
+ val <<= 6;
+ got++;
+ }
+
+ // now pull out however many valid bytes we got
+ val >>= 8; // always skip first one
+ if (size == 2) {
+ outbuf[pos + 1] = (byte)(val & 0xff);
+ }
+ val >>= 8;
+ outbuf[pos] = (byte)(val & 0xff);
+ // len -= size; // not needed, return below
+ pos += size;
+ return pos - pos0;
+ } else {
+ // got a valid byte
+ val <<= 6;
+ got++;
+ val |= i;
+ }
+ }
+
+ // read 4 valid characters, now extract 3 bytes
+ outbuf[pos + 2] = (byte)(val & 0xff);
+ val >>= 8;
+ outbuf[pos + 1] = (byte)(val & 0xff);
+ val >>= 8;
+ outbuf[pos] = (byte)(val & 0xff);
+ len -= 3;
+ pos += 3;
+ }
+ return pos - pos0;
+ }
+
+ /**
+ * Read the next valid byte from the input stream.
+ * Buffer lots of data from underlying stream in input_buffer,
+ * for efficiency.
+ *
+ * @return the next byte, -1 on EOF, or -2 if next byte is '='
+ * (padding at end of encoded data)
+ */
+ private int getByte() throws IOException {
+ int c;
+ do {
+ if (input_pos >= input_len) {
+ try {
+ input_len = in.read(input_buffer);
+ } catch (EOFException ex) {
+ return -1;
+ }
+ if (input_len <= 0) {
+ return -1;
+ }
+ input_pos = 0;
+ }
+ // get the next byte in the buffer
+ c = input_buffer[input_pos++] & 0xff;
+ // is it a padding byte?
+ if (c == '=') {
+ return -2;
+ }
+ // no, convert it
+ c = pem_convert_array[c];
+ // loop until we get a legitimate byte
+ } while (c == -1);
+ return c;
+ }
+
+ /**
+ * Return the most recent characters, for use in an error message.
+ */
+ private String recentChars() {
+ // reach into the input buffer and extract up to 10
+ // recent characters, to help in debugging.
+ StringBuilder errstr = new StringBuilder();
+ int nc = input_pos > 10 ? 10 : input_pos;
+ if (nc > 0) {
+ errstr.append(", the ").append(nc).append(" most recent characters were: \"");
+ for (int k = input_pos - nc; k < input_pos; k++) {
+ char c = (char)(input_buffer[k] & 0xff);
+ switch (c) {
+ case '\r': errstr.append("\\r"); break;
+ case '\n': errstr.append("\\n"); break;
+ case '\t': errstr.append("\\t"); break;
+ default:
+ if (c >= ' ' && c < 0177) {
+ errstr.append(c);
+ } else {
+ errstr.append("\\").append((int)c);
+ }
+ }
+ }
+ errstr.append("\"");
+ }
+ return errstr.toString();
+ }
+
+ /**
+ * Base64 decode a byte array. No line breaks are allowed.
+ * This method is suitable for short strings, such as those
+ * in the IMAP AUTHENTICATE protocol, but not to decode the
+ * entire content of a MIME part.
+ *
+ * NOTE: inbuf may only contain valid base64 characters.
+ * Whitespace is not ignored.
+ */
+ public static byte[] decode(byte[] inbuf) {
+ int size = (inbuf.length / 4) * 3;
+ if (size == 0) {
+ return inbuf;
+ }
+
+ if (inbuf[inbuf.length - 1] == '=') {
+ size--;
+ if (inbuf[inbuf.length - 2] == '=') {
+ size--;
+ }
+ }
+ byte[] outbuf = new byte[size];
+
+ int inpos = 0, outpos = 0;
+ size = inbuf.length;
+ while (size > 0) {
+ int val;
+ int osize = 3;
+ val = pem_convert_array[inbuf[inpos++] & 0xff];
+ val <<= 6;
+ val |= pem_convert_array[inbuf[inpos++] & 0xff];
+ val <<= 6;
+ if (inbuf[inpos] != '=') {
+ val |= pem_convert_array[inbuf[inpos++] & 0xff];
+ } else {
+ osize--;
+ }
+ val <<= 6;
+ if (inbuf[inpos] != '=') {
+ val |= pem_convert_array[inbuf[inpos++] & 0xff];
+ } else {
+ osize--;
+ }
+ if (osize > 2) {
+ outbuf[outpos + 2] = (byte)(val & 0xff);
+ }
+ val >>= 8;
+ if (osize > 1) {
+ outbuf[outpos + 1] = (byte)(val & 0xff);
+ }
+ val >>= 8;
+ outbuf[outpos] = (byte)(val & 0xff);
+ outpos += osize;
+ size -= 4;
+ }
+ return outbuf;
+ }
+
+ /*** begin TEST program ***
+ public static void main(String argv[]) throws Exception {
+ FileInputStream infile = new FileInputStream(argv[0]);
+ BASE64DecoderStream decoder = new BASE64DecoderStream(infile);
+ int c;
+
+ while ((c = decoder.read()) != -1)
+ System.out.print((char)c);
+ System.out.flush();
+ }
+ *** end TEST program ***/
+}