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8222187: java.util.Base64.Decoder stream adds unexpected null bytes at the end
Reviewed-by: lancea, rriggs
This commit is contained in:
Raffaello Giulietti
Lance Andersen
parent
45e17d8dd2
commit
4d43cf9fc6
2 changed files with 165 additions and 91 deletions
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@ -1,5 +1,5 @@
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/*
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* Copyright (c) 2012, 2019, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@ -30,7 +30,6 @@ import java.io.InputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.nio.ByteBuffer;
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import java.nio.charset.StandardCharsets;
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import sun.nio.cs.ISO_8859_1;
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@ -961,12 +960,15 @@ public class Base64 {
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private final InputStream is;
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private final boolean isMIME;
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private final int[] base64; // base64 -> byte mapping
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private int bits = 0; // 24-bit buffer for decoding
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private int nextin = 18; // next available "off" in "bits" for input;
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// -> 18, 12, 6, 0
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private int nextout = -8; // next available "off" in "bits" for output;
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// -> 8, 0, -8 (no byte for output)
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private final int[] base64; // base64 -> byte mapping
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private int bits = 0; // 24-bit buffer for decoding
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/* writing bit pos inside bits; one of 24 (left, msb), 18, 12, 6, 0 */
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private int wpos = 0;
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/* reading bit pos inside bits: one of 24 (left, msb), 16, 8, 0 */
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private int rpos = 0;
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private boolean eof = false;
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private boolean closed = false;
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@ -983,107 +985,153 @@ public class Base64 {
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return read(sbBuf, 0, 1) == -1 ? -1 : sbBuf[0] & 0xff;
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}
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private int eof(byte[] b, int off, int len, int oldOff)
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throws IOException
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{
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private int leftovers(byte[] b, int off, int pos, int limit) {
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eof = true;
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if (nextin != 18) {
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if (nextin == 12)
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throw new IOException("Base64 stream has one un-decoded dangling byte.");
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// treat ending xx/xxx without padding character legal.
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// same logic as v == '=' below
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b[off++] = (byte)(bits >> (16));
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if (nextin == 0) { // only one padding byte
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if (len == 1) { // no enough output space
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bits >>= 8; // shift to lowest byte
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nextout = 0;
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} else {
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b[off++] = (byte) (bits >> 8);
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}
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}
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/*
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* We use a loop here, as this method is executed only a few times.
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* Unrolling the loop would probably not contribute much here.
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*/
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while (rpos - 8 >= wpos && pos != limit) {
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rpos -= 8;
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b[pos++] = (byte) (bits >> rpos);
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}
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return off == oldOff ? -1 : off - oldOff;
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return pos - off != 0 || rpos - 8 >= wpos ? pos - off : -1;
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}
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private int padding(byte[] b, int off, int len, int oldOff)
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throws IOException
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{
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// = shiftto==18 unnecessary padding
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// x= shiftto==12 dangling x, invalid unit
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// xx= shiftto==6 && missing last '='
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// xx=y or last is not '='
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if (nextin == 18 || nextin == 12 ||
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nextin == 6 && is.read() != '=') {
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throw new IOException("Illegal base64 ending sequence:" + nextin);
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private int eof(byte[] b, int off, int pos, int limit) throws IOException {
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/*
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* pos != limit
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*
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* wpos == 18: x dangling single x, invalid unit
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* accept ending xx or xxx without padding characters
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*/
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if (wpos == 18) {
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throw new IOException("Base64 stream has one un-decoded dangling byte.");
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}
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b[off++] = (byte)(bits >> (16));
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if (nextin == 0) { // only one padding byte
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if (len == 1) { // no enough output space
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bits >>= 8; // shift to lowest byte
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nextout = 0;
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} else {
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b[off++] = (byte) (bits >> 8);
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}
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rpos = 24;
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return leftovers(b, off, pos, limit);
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}
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private int padding(byte[] b, int off, int pos, int limit) throws IOException {
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/*
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* pos != limit
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*
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* wpos == 24: = (unnecessary padding)
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* wpos == 18: x= (dangling single x, invalid unit)
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* wpos == 12 and missing last '=': xx= (invalid padding)
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* wpos == 12 and last is not '=': xx=x (invalid padding)
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*/
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if (wpos >= 18 || wpos == 12 && is.read() != '=') {
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throw new IOException("Illegal base64 ending sequence:" + wpos);
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}
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eof = true;
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return off - oldOff;
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rpos = 24;
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return leftovers(b, off, pos, limit);
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}
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@Override
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public int read(byte[] b, int off, int len) throws IOException {
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if (closed)
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if (closed) {
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throw new IOException("Stream is closed");
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if (eof && nextout < 0) // eof and no leftover
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return -1;
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if (off < 0 || len < 0 || len > b.length - off)
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throw new IndexOutOfBoundsException();
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int oldOff = off;
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while (nextout >= 0) { // leftover output byte(s) in bits buf
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if (len == 0)
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return off - oldOff;
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b[off++] = (byte)(bits >> nextout);
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len--;
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nextout -= 8;
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}
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Objects.checkFromIndexSize(off, len, b.length);
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if (len == 0) {
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return 0;
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}
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/*
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* Rather than keeping 2 running vars (e.g., off and len),
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* we only keep one (pos), while definitely fixing the boundaries
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* of the range [off, limit).
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* More specifically, each use of pos as an index in b meets
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* pos - off >= 0 & limit - pos > 0
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*
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* Note that limit can overflow to Integer.MIN_VALUE. However,
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* as long as comparisons with pos are as coded, there's no harm.
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*/
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int pos = off;
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final int limit = off + len;
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if (eof) {
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return leftovers(b, off, pos, limit);
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}
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/*
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* Leftovers from previous invocation; here, wpos = 0.
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* There can be at most 2 leftover bytes (rpos <= 16).
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* Further, b has at least one free place.
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*
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* The logic could be coded as a loop, (as in method leftovers())
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* but the explicit "unrolling" makes it possible to generate
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* better byte extraction code.
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*/
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if (rpos == 16) {
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b[pos++] = (byte) (bits >> 8);
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rpos = 8;
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if (pos == limit) {
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return len;
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}
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}
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if (rpos == 8) {
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b[pos++] = (byte) bits;
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rpos = 0;
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if (pos == limit) {
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return len;
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}
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}
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bits = 0;
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while (len > 0) {
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int v = is.read();
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if (v == -1) {
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return eof(b, off, len, oldOff);
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wpos = 24;
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for (;;) {
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/* pos != limit & rpos == 0 */
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final int i = is.read();
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if (i < 0) {
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return eof(b, off, pos, limit);
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}
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if ((v = base64[v]) < 0) {
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if (v == -2) { // padding byte(s)
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return padding(b, off, len, oldOff);
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}
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final int v = base64[i];
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if (v < 0) {
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/*
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* i not in alphabet, thus
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* v == -2: i is '=', the padding
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* v == -1: i is something else, typically CR or LF
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*/
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if (v == -1) {
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if (!isMIME)
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throw new IOException("Illegal base64 character " +
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Integer.toString(v, 16));
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continue; // skip if for rfc2045
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if (isMIME) {
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continue;
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}
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throw new IOException("Illegal base64 character 0x" +
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Integer.toHexString(i));
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}
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// neve be here
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return padding(b, off, pos, limit);
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}
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bits |= (v << nextin);
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if (nextin == 0) {
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nextin = 18; // clear for next in
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b[off++] = (byte)(bits >> 16);
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if (len == 1) {
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nextout = 8; // 2 bytes left in bits
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break;
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}
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b[off++] = (byte)(bits >> 8);
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if (len == 2) {
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nextout = 0; // 1 byte left in bits
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break;
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}
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b[off++] = (byte)bits;
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len -= 3;
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wpos -= 6;
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bits |= v << wpos;
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if (wpos != 0) {
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continue;
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}
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if (limit - pos >= 3) {
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/* frequently taken fast path, no need to track rpos */
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b[pos++] = (byte) (bits >> 16);
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b[pos++] = (byte) (bits >> 8);
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b[pos++] = (byte) bits;
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bits = 0;
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} else {
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nextin -= 6;
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wpos = 24;
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if (pos == limit) {
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return len;
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}
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continue;
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}
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/* b has either 1 or 2 free places */
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b[pos++] = (byte) (bits >> 16);
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if (pos == limit) {
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rpos = 16;
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return len;
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}
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b[pos++] = (byte) (bits >> 8);
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/* pos == limit, no need for an if */
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rpos = 8;
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return len;
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}
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return off - oldOff;
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}
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@Override
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