This is a rewrite of feature vectors in lnwire. This has a few
benefits:
1) a simpler interface
2) separate structs for a plain set of feature bits and a feature
vector with associated feature names
their respective feature sets
3) loosened requirements that bits MUST be assigned in pairs
4) fix endianness of encoding/decoding
This commit fixes an incorrectly calculated size of a
*FeatureVector in the serializedSize() function. go-fuzz
found that when calling NewFeatureVectorFromReader, if
a flag is invalid, it is not added to f.flags. However,
it will skip the index that wasn't included. This
becomes a problem when serializedSize() calculates the
length of f.flags via len() which can lead to an index
out of range since certain flags may be missing.
This commit fixes a bug lingering in the decoding of the feature
vectors which was masked by the prior method of reading the _entire_
message from the stream before parsing it. The issue was that
performing a zero-byte Read on an io.Reader that’s purely streaming
will result in an indefinite block. We fix this bug by properly using
io.ReadFull in this context.
This commit removes the String() method from the FeatureVector as it
can produce confusing output when revving a feature vector and not
knowing the strip mapping ahead of time.
'init' message is the first message reveals the features supported or required
by this node. Nodes wait for receipt of the other's features to simplify error
diagnosis where features are incompatible. This message will help negotioate the
the features which are supported by both sides.
