Aiden Luo created GUACAMOLE-616:
-----------------------------------
Summary: Incorrect instruction element length handle because of
Java's char type
Key: GUACAMOLE-616
URL: https://issues.apache.org/jira/browse/GUACAMOLE-616
Project: Guacamole
Issue Type: Bug
Components: guacamole-common
Affects Versions: 0.9.14
Reporter: Aiden Luo
The definition of guacamole instruction:
{quote}The Guacamole protocol consists of instructions. Each instruction is a
comma-delimited list followed by a terminating semicolon, where the first
element of the list is the instruction opcode, and all following elements are
the arguments for that instruction:
OPCODE,ARG1,ARG2,ARG3,...;
Each element of the list has a positive decimal integer length prefix
separated by the value of the element by a period. This length denotes the
number of Unicode characters in the value of the element, which is encoded in
UTF-8:
LENGTH.VALUE
{quote}
Which means the element's values will be encoded in UTF-8。That means we must
use correct UTF-8 encoder/decoder to handle the instruction. But in
guacamole-common, the parser use Java's char type to parse which only can store
partial Unicode char.
Problem code
[https://github.com/apache/guacamole-client/blob/master/guacamole-common/src/main/java/org/apache/guacamole/protocol/GuacamoleParser.java#L164]
{code:java}
if (state == State.PARSING_CONTENT && charsParsed + elementLength + 1 <=
length) {
// Read element
String element = new String(chunk, offset + charsParsed, elementLength);
charsParsed += elementLength;
elementLength = 0;
...{code}
In the code above, bytes of a unicode char may not equal to a java char.
I also check the guacamole-server implementation, all work fine.
Correct code
[https://github.com/apache/guacamole-server/blob/master/src/libguac/parser.c#L113]
{code:java}
/* Advance to next character */
parser->__element_length--;
char_buffer += char_length;{code}
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