fix(pdu): correct ShareDataHeader uncompressedLength calculation#1148
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Benoît Cortier (CBenoit) merged 1 commit intoDevolutions:masterfrom Mar 5, 2026
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The uncompressedLength field in ShareDataHeader::encode() included the sizes of pduType2, compressedType, and compressedLength fields (4 extra bytes) on top of the actual PDU payload size. Per MS-RDPBCGR 2.2.8.1.1.1.2, uncompressedLength should contain only the payload size. This matches FreeRDP's implementation. pacmancoder confirmed this as a bug in May 2024: Devolutions#447 (comment) Fixes part of Devolutions#447
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Summary
ShareDataHeader::encode()was calculatinguncompressedLengthaspayload_size + 4(adding pduType2, compressedType, and compressedLengthfield sizes). Per MS-RDPBCGR 2.2.8.1.1.1.2, this field should contain
only the uncompressed payload size.
Vladyslav Nikonov (@pacmancoder) confirmed this as a bug in May 2024
(#447 (comment)):
"pretty sure this is a bug on our side"
FreeRDP encodes only the payload size. Servers tolerate both values since
the decode path does not validate
uncompressedLengthagainst actualpayload size, but the current encoding does not match the spec.
Changes
ironrdp-pdu/src/rdp/headers.rsironrdp-testsuite-core/src/rdp.rsVerification
cargo xtask check fmt,cargo xtask check lints, andcargo xtask check testsall pass.Fixes part of #447