com.blade.web.multipart.MultipartReader Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE
* file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file
* to You 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 com.blade.web.multipart;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
/**
*
* Low level API for processing file uploads.
*
*
* This class can be used to process data streams conforming to MIME 'multipart' format as defined in RFC 1867. Arbitrarily large amounts of data in the stream can be
* processed under constant memory usage.
*
*
* The format of the stream is defined in the following way:
*
*
* multipart-body := preamble 1*encapsulation close-delimiter epilogue
* encapsulation := delimiter body CRLF
* delimiter := "--" boundary CRLF
* close-delimiter := "--" boudary "--"
* preamble := <ignore>
* epilogue := <ignore>
* body := header-part CRLF body-part
* header-part := 1*header CRLF
* header := header-name ":" header-value
* header-name := <printable ascii characters except ":">
* header-value := <any ascii characters except CR & LF>
* body-data := <arbitrary data>
*
*
*
* Note that body-data can contain another mulipart entity. There is limited support for single pass processing of such
* nested streams. The nested stream is required to have a boundary token of the same length as the
* parent stream (see {@link #setBoundary(byte[])}).
*
*
* Here is an example of usage of this class.
*
*
* try {
* MultipartStream multipartStream = new MultipartStream(input, boundary);
* boolean nextPart = multipartStream.skipPreamble();
* OutputStream output;
* while (nextPart) {
* String header = multipartStream.readHeaders();
* // process headers
* // create some output stream
* multipartStream.readBodyData(output);
* nextPart = multipartStream.readBoundary();
* }
* } catch (MultipartStream.MalformedStreamException e) {
* // the stream failed to follow required syntax
* } catch (IOException e) {
* // a read or write error occurred
* }
*
*
* @author Rafal Krzewski
* @author Martin Cooper
* @author Sean C. Sullivan
*
* @version $Id: MultipartStream.java 735374 2009-01-18 02:18:45Z jochen $
*/
public class MultipartReader {
/**
* The Carriage Return ASCII character value.
*/
public static final byte CR = 0x0D;
/**
* The Line Feed ASCII character value.
*/
public static final byte LF = 0x0A;
/**
* The dash (-) ASCII character value.
*/
public static final byte DASH = 0x2D;
/**
* The maximum length of header-part that will be processed (10 kilobytes = 10240 bytes.).
*/
public static final int HEADER_PART_SIZE_MAX = 10240;
/**
* The default length of the buffer used for processing a request.
*/
protected static final int DEFAULT_BUFSIZE = 4096;
/**
* A byte sequence that marks the end of header-part (CRLFCRLF).
*/
protected static final byte[] HEADER_SEPARATOR = { CR, LF, CR, LF };
/**
* A byte sequence that that follows a delimiter that will be followed by an encapsulation (CRLF).
*/
protected static final byte[] FIELD_SEPARATOR = { CR, LF };
/**
* A byte sequence that that follows a delimiter of the last encapsulation in the stream (--).
*/
protected static final byte[] STREAM_TERMINATOR = { DASH, DASH };
/**
* A byte sequence that precedes a boundary (CRLF--).
*/
protected static final byte[] BOUNDARY_PREFIX = { CR, LF, DASH, DASH };
/**
* The input stream from which data is read.
*/
private final InputStream input;
/**
* The length of the boundary token plus the leading CRLF--.
*/
private int boundaryLength;
/**
* The amount of data, in bytes, that must be kept in the buffer in order to detect delimiters reliably.
*/
private int keepRegion;
/**
* The byte sequence that partitions the stream.
*/
private byte[] boundary;
/**
* The length of the buffer used for processing the request.
*/
private final int bufSize;
/**
* The buffer used for processing the request.
*/
private final byte[] buffer;
/**
* The index of first valid character in the buffer.
* 0 <= head < bufSize
*/
private int head;
/**
* The index of last valid characer in the buffer + 1.
* 0 <= tail <= bufSize
*/
private int tail;
/**
* The content encoding to use when reading headers.
*/
private String headerEncoding;
/**
*
* Constructs a MultipartStream with a custom size buffer.
*
*
* Note that the buffer must be at least big enough to contain the boundary string, plus 4 characters for CR/LF and
* double dash, plus at least one byte of data. Too small a buffer size setting will degrade performance.
*
* @param input The InputStream to serve as a data source.
* @param boundary The token used for dividing the stream into encapsulations.
* @param bufSize The size of the buffer to be used, in bytes.
*
*/
public MultipartReader(InputStream input, byte[] boundary, int bufSize) {
this.input = input;
this.bufSize = bufSize;
this.buffer = new byte[bufSize];
// prepend CR/LF to the boundary to chop trailing CR/LF from body-data tokens.
this.boundary = new byte[boundary.length + BOUNDARY_PREFIX.length];
this.boundaryLength = boundary.length + BOUNDARY_PREFIX.length;
this.keepRegion = this.boundary.length;
System.arraycopy(BOUNDARY_PREFIX, 0, this.boundary, 0, BOUNDARY_PREFIX.length);
System.arraycopy(boundary, 0, this.boundary, BOUNDARY_PREFIX.length, boundary.length);
head = 0;
tail = 0;
}
/**
* Constructs a MultipartStream with a default size buffer.
*
* @param input The InputStream to serve as a data source.
* @param boundary The token used for dividing the stream into encapsulations.
*/
public MultipartReader(InputStream input, byte[] boundary) {
this(input, boundary, DEFAULT_BUFSIZE);
}
/**
* Retrieves the character encoding used when reading the headers of an individual part. When not specified, or
* null, the platform default encoding is used.
*
* @return The encoding used to read part headers.
*/
public String getHeaderEncoding() {
return headerEncoding;
}
/**
* Specifies the character encoding to be used when reading the headers of individual parts. When not specified, or
* null, the platform default encoding is used.
*
* @param encoding The encoding used to read part headers.
*/
public void setHeaderEncoding(String encoding) {
headerEncoding = encoding;
}
/**
* Reads a byte from the buffer, and refills it as necessary.
*
* @return The next byte from the input stream.
* @throws IOException if there is no more data available.
*/
public byte readByte() throws IOException {
// buffer depleted ?
if (head == tail) {
head = 0;
// Refill.
tail = input.read(buffer, head, bufSize);
if (tail == -1) {
// no more data available.
throw new IOException("No more data is available");
}
}
return buffer[head++];
}
/**
* Skips a boundary token, and checks whether more encapsulations are contained in the
* stream.
*
* @return true if there are more encapsulations in this stream; false otherwise.
*
* @throws MalformedStreamException if the stream ends unexpecetedly or fails to follow required syntax.
*/
public boolean readBoundary() throws MalformedStreamException {
byte[] marker = new byte[2];
boolean nextChunk = false;
head += boundaryLength;
try {
marker[0] = readByte();
marker[1] = readByte();
if (arrayequals(marker, STREAM_TERMINATOR, 2)) {
nextChunk = false;
} else if (arrayequals(marker, FIELD_SEPARATOR, 2)) {
nextChunk = true;
} else {
throw new MalformedStreamException("Unexpected characters follow a boundary");
}
} catch (IOException e) {
throw new MalformedStreamException("Stream ended unexpectedly");
}
return nextChunk;
}
/**
*
Changes the boundary token used for partitioning the stream.
*
* This method allows single pass processing of nested multipart streams.
*
* The boundary token of the nested stream is required to be of the same length as the boundary token
* in parent stream.
*
* Restoring the parent stream boundary token after processing of a nested stream is left to the application.
*
* @param boundary The boundary to be used for parsing of the nested stream.
*
* @throws IllegalBoundaryException if the boundary has a different length than the one being currently
* parsed.
*/
public void setBoundary(byte[] boundary) throws IllegalBoundaryException {
if (boundary.length != boundaryLength - BOUNDARY_PREFIX.length) {
throw new IllegalBoundaryException("The length of a boundary token can not be changed");
}
System.arraycopy(boundary, 0, this.boundary, BOUNDARY_PREFIX.length, boundary.length);
}
/**
* Reads the header-part of the current encapsulation.
*
* Headers are returned verbatim to the input stream, including the trailing CRLF marker. Parsing is
* left to the application.
*
* @return The header-part of the current encapsulation.
* @throws MalformedStreamException if the stream ends unexpecetedly.
*/
public String readHeaders() throws MalformedStreamException {
int i = 0;
byte b;
// to support multi-byte characters
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int size = 0;
while (i < HEADER_SEPARATOR.length) {
try {
b = readByte();
} catch (IOException e) {
throw new MalformedStreamException("Stream ended unexpectedly");
}
if (++size > HEADER_PART_SIZE_MAX) {
throw new MalformedStreamException("Header section has more than " + HEADER_PART_SIZE_MAX
+ " bytes (maybe it is not properly terminated)");
}
if (b == HEADER_SEPARATOR[i]) {
i++;
} else {
i = 0;
}
baos.write(b);
}
String headers = null;
if (headerEncoding != null) {
try {
headers = baos.toString(headerEncoding);
} catch (UnsupportedEncodingException e) {
// fall back to platform default if specified encoding is not supported.
headers = baos.toString();
}
} else {
headers = baos.toString();
}
return headers;
}
/**
* Reads body-data from the current encapsulation and writes its contents into the output
* Stream.
*
* Arbitrary large amounts of data can be processed by this method using a constant size buffer.
*
* @param output The Stream to write data into. May be null, in which case this method is equivalent to
* {@link #discardBodyData()}.
*
* @return the amount of data written.
*
* @throws MalformedStreamException if the stream ends unexpectedly.
* @throws IOException if an i/o error occurs.
*/
public int readBodyData(OutputStream output) throws MalformedStreamException, IOException {
final InputStream istream = newInputStream();
return (int) Streams.copy(istream, output, false);
}
/**
* Creates a new {@link ItemInputStream}.
*
* @return A new instance of {@link ItemInputStream}.
*/
protected ItemInputStream newInputStream() {
return new ItemInputStream();
}
/**
* Reads body-data from the current encapsulation and discards it.
*
* Use this method to skip encapsulations you don't need or don't understand.
*
* @return The amount of data discarded.
* @throws MalformedStreamException if the stream ends unexpectedly.
* @throws IOException if an i/o error occurs.
*/
public int discardBodyData() throws MalformedStreamException, IOException {
return readBodyData(null);
}
/**
* Finds the beginning of the first encapsulation.
*
* @return true if an encapsulation was found in the stream.
* @throws IOException if an i/o error occurs.
*/
public boolean skipPreamble() throws IOException {
// first delimiter may be not preceded with a CRLF.
System.arraycopy(boundary, 2, boundary, 0, boundary.length - 2);
boundaryLength = boundary.length - 2;
try {
// discard all data up to the delimiter.
discardBodyData();
// read boundary - if succeded, the stream contains an encapsulation.
return readBoundary();
} catch (MalformedStreamException e) {
return false;
} finally {
// restore delimiter.
System.arraycopy(boundary, 0, boundary, 2, boundary.length - 2);
boundaryLength = boundary.length;
boundary[0] = CR;
boundary[1] = LF;
}
}
/**
* Compares count first bytes in the arrays a and b.
*
* @param a The first array to compare.
* @param b The second array to compare.
* @param count How many bytes should be compared.
*
* @return true if count first bytes in arrays a and b are
* equal.
*/
public static boolean arrayequals(byte[] a, byte[] b, int count) {
for (int i = 0; i < count; i++) {
if (a[i] != b[i]) {
return false;
}
}
return true;
}
/**
* Searches for a byte of specified value in the buffer, starting at the specified
* position.
*
* @param value The value to find.
* @param pos The starting position for searching.
*
* @return The position of byte found, counting from beginning of the buffer, or -1 if not
* found.
*/
protected int findByte(byte value, int pos) {
for (int i = pos; i < tail; i++) {
if (buffer[i] == value) {
return i;
}
}
return -1;
}
/**
* Searches for the boundary in the buffer region delimited by head and
* tail.
*
* @return The position of the boundary found, counting from the beginning of the buffer, or
* -1 if not found.
*/
protected int findSeparator() {
int first;
int match = 0;
int maxpos = tail - boundaryLength;
for (first = head; (first <= maxpos) && (match != boundaryLength); first++) {
first = findByte(boundary[0], first);
if (first == -1 || (first > maxpos)) {
return -1;
}
for (match = 1; match < boundaryLength; match++) {
if (buffer[first + match] != boundary[match]) {
break;
}
}
}
if (match == boundaryLength) {
return first - 1;
}
return -1;
}
/**
* Thrown to indicate that the input stream fails to follow the required syntax.
*/
@SuppressWarnings("serial")
public static class MalformedStreamException extends IOException {
/**
* Constructs a MalformedStreamException with no detail message.
*/
public MalformedStreamException() {
super();
}
/**
* Constructs an MalformedStreamException with the specified detail message.
*
* @param message The detail message.
*/
public MalformedStreamException(String message) {
super(message);
}
}
/**
* Thrown upon attempt of setting an invalid boundary token.
*/
@SuppressWarnings("serial")
public static class IllegalBoundaryException extends IOException {
/**
* Constructs an IllegalBoundaryException with no detail message.
*/
public IllegalBoundaryException() {
super();
}
/**
* Constructs an IllegalBoundaryException with the specified detail message.
*
* @param message The detail message.
*/
public IllegalBoundaryException(String message) {
super(message);
}
}
/**
* An {@link InputStream} for reading an items contents.
*/
public class ItemInputStream extends InputStream implements Closeable {
/* The number of bytes, which have been read so far */
private long total;
/* The number of bytes, which must be hold, because they might be a part of the boundary */
private int pad;
/* The current offset in the buffer */
private int pos;
/* Whether the stream is already closed. */
private boolean closed;
/**
* Creates a new instance.
*/
ItemInputStream() {
findSeparator();
}
/**
* Called for finding the separator.
*/
private void findSeparator() {
pos = MultipartReader.this.findSeparator();
if (pos == -1) {
if (tail - head > keepRegion) {
pad = keepRegion;
} else {
pad = tail - head;
}
}
}
/**
* Returns the number of bytes, which have been read by the stream.
*
* @return Number of bytes, which have been read so far.
*/
public long getBytesRead() {
return total;
}
/**
* Returns the number of bytes, which are currently available, without blocking.
*
* @return Number of bytes in the buffer.
* @throws IOException An I/O error occurs.
*/
public int available() throws IOException {
if (pos == -1) {
return tail - head - pad;
}
return pos - head;
}
/* Offset when converting negative bytes to integers */
private static final int BYTE_POSITIVE_OFFSET = 256;
/**
* Returns the next byte in the stream.
*
* @return The next byte in the stream, as a non-negative integer, or -1 for EOF.
* @throws IOException An I/O error occurred.
*/
public int read() throws IOException {
if (closed) {
throw new IOException("The stream is closed.");
}
if (available() == 0) {
if (makeAvailable() == 0) {
return -1;
}
}
++total;
int b = buffer[head++];
if (b >= 0) {
return b;
}
return b + BYTE_POSITIVE_OFFSET;
}
/**
* Reads bytes into the given buffer.
*
* @param b The destination buffer, where to write to.
* @param off Offset of the first byte in the buffer.
* @param len Maximum number of bytes to read.
*
* @return Number of bytes, which have been actually read, or -1 for EOF.
* @throws IOException An I/O error occurred.
*/
public int read(byte[] b, int off, int len) throws IOException {
if (closed) {
throw new IOException("The stream is closed.");
}
if (len == 0) {
return 0;
}
int res = available();
if (res == 0) {
res = makeAvailable();
if (res == 0) {
return -1;
}
}
res = Math.min(res, len);
System.arraycopy(buffer, head, b, off, res);
head += res;
total += res;
return res;
}
/**
* Closes the input stream.
*
* @throws IOException An I/O error occurred.
*/
public void close() throws IOException {
close(false);
}
/**
* Closes the input stream.
*
* @param pCloseUnderlying Whether to close the underlying stream (hard close).
*
* @throws IOException An I/O error occurred.
*/
public void close(boolean pCloseUnderlying) throws IOException {
if (closed) {
return;
}
if (pCloseUnderlying) {
closed = true;
input.close();
} else {
for (;;) {
int av = available();
if (av == 0) {
av = makeAvailable();
if (av == 0) {
break;
}
}
skip(av);
}
}
closed = true;
}
/**
* Skips the given number of bytes.
*
* @param bytes Number of bytes to skip.
*
* @return The number of bytes, which have actually been skipped.
* @throws IOException An I/O error occurred.
*/
public long skip(long bytes) throws IOException {
if (closed) {
throw new IOException("The stream is closed.");
}
int av = available();
if (av == 0) {
av = makeAvailable();
if (av == 0) {
return 0;
}
}
long res = Math.min(av, bytes);
head += res;
return res;
}
/**
* Attempts to read more data.
*
* @return Number of available bytes
* @throws IOException An I/O error occurred.
*/
private int makeAvailable() throws IOException {
if (pos != -1) {
return 0;
}
// move the data to the beginning of the buffer
total += tail - head - pad;
System.arraycopy(buffer, tail - pad, buffer, 0, pad);
// refill buffer with new data
head = 0;
tail = pad;
for (;;) {
int bytesRead = input.read(buffer, tail, bufSize - tail);
if (bytesRead == -1) {
// the last pad amount is left in the buffer
// boundary can't be in there so signal an error condition.
final String msg = "Stream ended unexpectedly";
throw new MalformedStreamException(msg);
}
tail += bytesRead;
findSeparator();
int av = available();
if (av > 0 || pos != -1) {
return av;
}
}
}
/**
* Returns, whether the stream is closed.
*
* @return true, if the stream is closed, otherwise false.
*/
public boolean isClosed() {
return closed;
}
}
}