Fix reading UTF-8 strings (from OPC UA nodes) #832
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The previous logic could result in a `StringIndexOutOfBoundsException` upon calling `substring()`. Reason is that the calculated `realLength` is in bytes and the length of the created string is the number of characters. For UTF encodings, multiple bytes can be just one character. This causes `realLength` to be longer than the actual string and thus the `substring()`-call to fail. Fix this by applying `realLength` to the byte-array instead of the string. This is done by utilizing a different String constructor. Note that on the UTF16 cases the `realLength` needs to be incremented by 2 to account for the two added bytes. This commit contains a regression test that fails without these adaptations. Signed-off-by: Marc Aurel Fritz <Marc-Aurel.Fritz@plansee.com>
Previously, the inner switch statement at the UTF-16 cases would not convert encoding to upper case. This prevented matching from working properly. Do so directly at the beginning in order to prevent future bugs. Signed-off-by: Marc Aurel Fritz <Marc-Aurel.Fritz@plansee.com>
Prevent having the same logic twice. Signed-off-by: Marc Aurel Fritz <Marc-Aurel.Fritz@plansee.com>
sruehl
approved these changes
Mar 7, 2023
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Thanks for the PR: LGTM, although @chrisdutz should check the ASCII part regarding the padding
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When reading string values via the OPC UA protocol a
StringIndexOutOfBoundsExceptionwas thrown whenever the string contained non-ASCII characters. Upon further inspection, the problem could be pinned down to the logic inreadString()ofReadBufferByteBased.The
readString()function inReadBufferByteBasedcould result in aStringIndexOutOfBoundsExceptionupon callingsubstring(). Reason is that the calculatedrealLengthis in bytes and the length of the created string is the number of characters. For UTF encodings, multiple bytes can be just one character. This causesrealLengthto be longer than the actual string and thus thesubstring()-call to fail.This PR fixes the issue by applying
realLengthto the byte-length instead of the string length: The byte array is sliced to lengthrealLengthand then converted to the final string.substring()isn't used anymore.The fix can be verified via the included regression test and has additionally been tested locally using the OPC UA protocol.
Maybe other protocols were also affected?
Additionally I've included some other minor fixes for the logic. Check the commits for these.
Regards,
Marc