lnwire: implement cautious zlib decoding for channel range queries #1399
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erkarl
previously approved these changes
Jun 16, 2018
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nice work. however it doesn't seem to play nicely with ACINQ. |
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@robtex there's no issue there. Basically right now we don't also track that we sent out a query, they respond, but then we say we didn't send out the query. It's due to the fact that the gossiper doesn't tell the syncer that it has a new querying incoming. So that's just a logging issue. |
In this commit, we implement zlib encoding and decoding for the channel range queries. Notably, we utilize an io.LimitedReader to ensure that we can enforce a hard cap on the total number of bytes we'll ever allocate in a decoding attempt.
…odings In this commit, we add a new package level mutex. Each time we decode a new set of chan IDs w/ zlib, we also grab this mutex. The purpose here is to ensure that we only EVER allocate the maxZlibBufSize globally across all peers. Otherwise, it may be possible for us to allocate up to 64 MB for _each_ peer, exposing an easy OOM attack vector.
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In this commit, we implement zlib decoding and encoding for the
EncodingSortedZlibencoding type. Before this commit, we only supported the sorted plain encoding. When decoding we utilize anio.LimitedReaderto ensure that we can precisely (as much given the runtime+GC) control how much memory we allocate during decoding. On top of that, we also add a package level mutex to limit the total number of decoding instances to one. This ensures that we don't multiply our allocation limit across all peers.