fix: don't truncate decompressed packets that expand more than 2x - #750
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Decompress::decompress checked its loop-exit conditions using progress counters read before the current inflate call, so a drain call that filled the output buffer exactly broke out of the loop with data still pending inside zlib. The packet came back short and the leftover bytes desynced the stream for every later packet. Read the counters after the call instead, and add a regression test that round-trips partial-flush packets on a continuous stream - the shape real SSH traffic has, which the existing finished-stream tests don't cover. Fixes Eugeny#749
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Fixes #749.
Decompress::decompresschecked its loop-exit conditions using progress counters read before the current inflate call. A drain call that filled the output buffer exactly would break out of the loop with data still pending inside zlib: the packet came back short, and the leftover bytes corrupted the stream for every later packet. Any packet compressing better than 2:1 hit this, which killed every compressed session (e.g. OpenSSH clients withCompression yes).This reads the counters after the call instead, and adds a regression test that round-trips partial-flush packets on a continuous stream — the shape real SSH traffic has, which the existing finished-stream tests don't cover. The test fails without the fix (
sent 37 bytes, got 36 back) and passes with it; the full suite passes.