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GUAC-868: Port Guacamole parser from libguac. Add GuacamoleInstruction constructor which takes a List.

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This commit is contained in:
Michael Jumper
2014-09-27 20:09:27 -07:00
parent ef42d7db68
commit c26751239a
2 changed files with 258 additions and 0 deletions
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14
guacamole-common/src/main/java/org/glyptodon/guacamole/protocol/GuacamoleInstruction.java
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@@ -58,6 +58,20 @@ public class GuacamoleInstruction {
this.args = Collections.unmodifiableList(Arrays.asList(args));
}
/**
* Creates a new GuacamoleInstruction having the given Operation and
* list of arguments values. The list given will be used to back the
* internal list of arguments and the list returned by getArgs().
*
* @param opcode The opcode of the instruction to create.
* @param args The list of argument values to provide in the new
* instruction if any.
*/
public GuacamoleInstruction(String opcode, List<String> args) {
this.opcode = opcode;
this.args = Collections.unmodifiableList(args);
}
/**
* Returns the opcode associated with this GuacamoleInstruction.
* @return The opcode associated with this GuacamoleInstruction.

244
guacamole-common/src/main/java/org/glyptodon/guacamole/protocol/GuacamoleParser.java Normal file
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@@ -0,0 +1,244 @@
/*
* Copyright (C) 2014 Glyptodon LLC
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.glyptodon.guacamole.protocol;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import org.glyptodon.guacamole.GuacamoleException;
import org.glyptodon.guacamole.GuacamoleServerException;
/**
* Parser for the Guacamole protocol. Arbitrary instruction data is appended,
* and instructions are returned as a result. Invalid instructions result in
* exceptions.
*
* @author Michael Jumper
*/
public class GuacamoleParser implements Iterator<GuacamoleInstruction> {
/**
* The maximum number of characters per instruction.
*/
public static final int INSTRUCTION_MAX_LENGTH = 8192;
/**
* The maximum number of digits to allow per length prefix.
*/
public static final int INSTRUCTION_MAX_DIGITS = 5;
/**
* The maximum number of elements per instruction, including the opcode.
*/
public static final int INSTRUCTION_MAX_ELEMENTS = 64;
/**
* All possible states of the instruction parser.
*/
private enum State {
/**
* The parser is currently waiting for data to complete the length prefix
* of the current element of the instruction.
*/
PARSING_LENGTH,
/**
* The parser has finished reading the length prefix and is currently
* waiting for data to complete the content of the instruction.
*/
PARSING_CONTENT,
/**
* The instruction has been fully parsed.
*/
COMPLETE,
/**
* The instruction cannot be parsed because of a protocol error.
*/
ERROR
}
/**
* The latest parsed instruction, if any.
*/
private GuacamoleInstruction parsedInstruction;
/**
* The parse state of the instruction.
*/
private State state = State.PARSING_LENGTH;
/**
* The length of the current element, if known.
*/
private int elementLength = 0;
/**
* The number of elements currently parsed.
*/
private int elementCount = 0;
/**
* All currently parsed elements.
*/
private final String elements[] = new String[INSTRUCTION_MAX_ELEMENTS];
/**
* Appends data from the given buffer to the current instruction.
*
* @param chunk The buffer containing the data to append.
* @param offset The offset within the buffer where the data begins.
* @param length The length of the data to append.
* @return The number of characters appended, or 0 if complete instructions
* have already been parsed and must be read via next() before
* more data can be appended.
* @throws GuacamoleException If an error occurs while parsing the new data.
*/
public int append(char chunk[], int offset, int length) throws GuacamoleException {
int charsParsed = 0;
// Do not exceed maximum number of elements
if (elementCount == INSTRUCTION_MAX_ELEMENTS && state != State.COMPLETE) {
state = State.ERROR;
throw new GuacamoleServerException("Instruction contains too many elements.");
}
// Parse element length
if (state == State.PARSING_LENGTH) {
int parsedLength = elementLength;
while (charsParsed < length) {
// Pull next character
char c = chunk[offset + charsParsed++];
// If digit, add to length
if (c >= '0' && c <= '9')
parsedLength = parsedLength*10 + c - '0';
// If period, switch to parsing content
else if (c == '.') {
state = State.PARSING_CONTENT;
break;
}
// If not digit, parse error
else {
state = State.ERROR;
throw new GuacamoleServerException("Non-numeric character in element length.");
}
}
// If too long, parse error
if (parsedLength > INSTRUCTION_MAX_LENGTH) {
state = State.ERROR;
throw new GuacamoleServerException("Instruction exceeds maximum length.");
}
// Save length
elementLength = parsedLength;
} // end parse length
// Parse element content, if available
if (state == State.PARSING_CONTENT && charsParsed + elementLength + 1 <= length) {
// Read element
String element = new String(chunk, offset + charsParsed, elementLength);
charsParsed += elementLength;
elementLength = 0;
// Read terminator char following element
char terminator = chunk[offset + charsParsed++];
// Add element to currently parsed elements
elements[elementCount++] = element;
// If semicolon, store end-of-instruction
if (terminator == ';') {
state = State.COMPLETE;
parsedInstruction = new GuacamoleInstruction(elements[0],
Arrays.asList(elements).subList(1, elementCount));
}
// If comma, move on to next element
else if (terminator == ',')
state = State.PARSING_LENGTH;
// Otherwise, parse error
else {
state = State.ERROR;
throw new GuacamoleServerException("Element terminator of instruction was not ';' nor ','");
}
} // end parse content
return charsParsed;
}
/**
* Appends data from the given buffer to the current instruction.
*
* @param chunk The data to append.
* @return The number of characters appended, or 0 if complete instructions
* have already been parsed and must be read via next() before
* more data can be appended.
* @throws GuacamoleException If an error occurs while parsing the new data.
*/
public int append(char chunk[]) throws GuacamoleException {
return append(chunk, 0, chunk.length);
}
@Override
public boolean hasNext() {
return state == State.COMPLETE;
}
@Override
public GuacamoleInstruction next() {
// No instruction to return if not yet complete
if (state != State.COMPLETE)
return null;
// Reset for next instruction.
state = State.PARSING_LENGTH;
elementCount = 0;
elementLength = 0;
return parsedInstruction;
}
@Override
public void remove() {
throw new UnsupportedOperationException("GuacamoleParser does not support remove().");
}
}