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Fix for Remote port forwarding buffers can grow without limits (issue #…
…658) (#913) * Fix for Remote port forwarding buffers can grow without limits (issue #658) * Update test classes to use JUnit 5 * Fix MB computation
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194 changes: 194 additions & 0 deletions
194
src/main/java/net/schmizz/sshj/common/CircularBuffer.java
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,194 @@ | ||
| /* | ||
| * Copyright (C)2009 - SSHJ Contributors | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package net.schmizz.sshj.common; | ||
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| public class CircularBuffer<T extends CircularBuffer<T>> { | ||
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| public static class CircularBufferException | ||
| extends SSHException { | ||
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| public CircularBufferException(String message) { | ||
| super(message); | ||
| } | ||
| } | ||
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| public static final class PlainCircularBuffer | ||
| extends CircularBuffer<PlainCircularBuffer> { | ||
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| public PlainCircularBuffer(int size, int maxSize) { | ||
| super(size, maxSize); | ||
| } | ||
| } | ||
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| /** | ||
| * Maximum size of the internal array (one plus the maximum capacity of the buffer). | ||
| */ | ||
| private final int maxSize; | ||
| /** | ||
| * Internal array for the data. All bytes minus one can be used to avoid empty vs full ambiguity when rpos == wpos. | ||
| */ | ||
| private byte[] data; | ||
| /** | ||
| * Next read position. Wraps around the end of the internal array. When it reaches wpos, the buffer becomes empty. | ||
| * Can take the value data.length, which is equivalent to 0. | ||
| */ | ||
| private int rpos; | ||
| /** | ||
| * Next write position. Wraps around the end of the internal array. If it is equal to rpos, then the buffer is | ||
| * empty; the code does not allow wpos to reach rpos from the left. This implies that the buffer can store up to | ||
| * data.length - 1 bytes. Can take the value data.length, which is equivalent to 0. | ||
| */ | ||
| private int wpos; | ||
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| /** | ||
| * Determines the size to which to grow the internal array. | ||
| */ | ||
| private int getNextSize(int currentSize) { | ||
| // Use next power of 2. | ||
| int nextSize = 1; | ||
| while (nextSize < currentSize) { | ||
| nextSize <<= 1; | ||
| if (nextSize <= 0) { | ||
| return maxSize; | ||
| } | ||
| } | ||
| return Math.min(nextSize, maxSize); // limit to max size | ||
| } | ||
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| /** | ||
| * Creates a new circular buffer of the given size. The capacity of the buffer is one less than the size/ | ||
| */ | ||
| public CircularBuffer(int size, int maxSize) { | ||
| this.maxSize = maxSize; | ||
| if (size > maxSize) { | ||
| throw new IllegalArgumentException( | ||
| String.format("Initial requested size %d larger than maximum size %d", size, maxSize)); | ||
| } | ||
| int initialSize = getNextSize(size); | ||
| this.data = new byte[initialSize]; | ||
| this.rpos = 0; | ||
| this.wpos = 0; | ||
| } | ||
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| /** | ||
| * Data available in the buffer for reading. | ||
| */ | ||
| public int available() { | ||
| int available = wpos - rpos; | ||
| return available >= 0 ? available : available + data.length; // adjust if wpos is left of rpos | ||
| } | ||
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| private void ensureAvailable(int a) | ||
| throws CircularBufferException { | ||
| if (available() < a) { | ||
| throw new CircularBufferException("Underflow"); | ||
| } | ||
| } | ||
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| /** | ||
| * Returns how many more bytes this buffer can receive. | ||
| */ | ||
| public int maxPossibleRemainingCapacity() { | ||
| // Remaining capacity is one less than remaining space to ensure that wpos does not reach rpos from the left. | ||
| int remaining = rpos - wpos - 1; | ||
| if (remaining < 0) { | ||
| remaining += data.length; // adjust if rpos is left of wpos | ||
| } | ||
| // Add the maximum amount the internal array can grow. | ||
| return remaining + maxSize - data.length; | ||
| } | ||
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| /** | ||
| * If the internal array does not have room for "capacity" more bytes, resizes the array to make that room. | ||
| */ | ||
| void ensureCapacity(int capacity) throws CircularBufferException { | ||
| int available = available(); | ||
| int remaining = data.length - available; | ||
| // If capacity fits exactly in the remaining space, expand it; otherwise, wpos would reach rpos from the left. | ||
| if (remaining <= capacity) { | ||
| int neededSize = available + capacity + 1; | ||
| int nextSize = getNextSize(neededSize); | ||
| if (nextSize < neededSize) { | ||
| throw new CircularBufferException("Attempted overflow"); | ||
| } | ||
| byte[] tmp = new byte[nextSize]; | ||
| // Copy data to the beginning of the new array. | ||
| if (wpos >= rpos) { | ||
| System.arraycopy(data, rpos, tmp, 0, available); | ||
| wpos -= rpos; // wpos must be relative to the new rpos, which will be 0 | ||
| } else { | ||
| int tail = data.length - rpos; | ||
| System.arraycopy(data, rpos, tmp, 0, tail); // segment right of rpos | ||
| System.arraycopy(data, 0, tmp, tail, wpos); // segment left of wpos | ||
| wpos += tail; // wpos must be relative to the new rpos, which will be 0 | ||
| } | ||
| rpos = 0; | ||
| data = tmp; | ||
| } | ||
| } | ||
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| /** | ||
| * Reads data from this buffer into the provided array. | ||
| */ | ||
| public void readRawBytes(byte[] destination, int offset, int length) throws CircularBufferException { | ||
| ensureAvailable(length); | ||
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| int rposNext = rpos + length; | ||
| if (rposNext <= data.length) { | ||
| System.arraycopy(data, rpos, destination, offset, length); | ||
| } else { | ||
| int tail = data.length - rpos; | ||
| System.arraycopy(data, rpos, destination, offset, tail); // segment right of rpos | ||
| rposNext = length - tail; // rpos wraps around the end of the buffer | ||
| System.arraycopy(data, 0, destination, offset + tail, rposNext); // remainder | ||
| } | ||
| // This can make rpos equal data.length, which has the same effect as wpos being 0. | ||
| rpos = rposNext; | ||
| } | ||
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| /** | ||
| * Writes data to this buffer from the provided array. | ||
| */ | ||
| @SuppressWarnings("unchecked") | ||
| public T putRawBytes(byte[] source, int offset, int length) throws CircularBufferException { | ||
| ensureCapacity(length); | ||
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| int wposNext = wpos + length; | ||
| if (wposNext <= data.length) { | ||
| System.arraycopy(source, offset, data, wpos, length); | ||
| } else { | ||
| int tail = data.length - wpos; | ||
| System.arraycopy(source, offset, data, wpos, tail); // segment right of wpos | ||
| wposNext = length - tail; // wpos wraps around the end of the buffer | ||
| System.arraycopy(source, offset + tail, data, 0, wposNext); // remainder | ||
| } | ||
| // This can make wpos equal data.length, which has the same effect as wpos being 0. | ||
| wpos = wposNext; | ||
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| return (T) this; | ||
| } | ||
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| // Used only for testing. | ||
| int length() { | ||
| return data.length; | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return "CircularBuffer [rpos=" + rpos + ", wpos=" + wpos + ", size=" + data.length + "]"; | ||
| } | ||
|
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| } |
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