It is best to have deterministic fuzz targets, so that if a failure
occurs, it can be easily reproduced.
This commit swaps the cryptographically secure RNG for a deterministic
one seeded from fuzzer input.
Move the functionality directly into completeHandshake instead. If a
failure does happen at any point during the handshake, it is beneficial
to know which line it happens on for debugging. The helper function was
hiding this information.
This commit was previously split into the following parts to ease
review:
- 2d746f68: replace imports
- 4008f0fd: use ecdsa.Signature
- 849e33d1: remove btcec.S256()
- b8f6ebbd: use v2 library correctly
- fa80bca9: bump go modules
In this commit, we implement a simple optimization that dramatically
reduces the number of allocations we need to make when we decrypt a new
message. Before this commit, we would pass in a `nil` value to the
`Decrypt` method which meant that it would always allocate a new
buffers.
Rather than force this behavior, in this commit, we pass in the
ciphertext buffer (with a length of zero), such that the decryption
operation will simply copy the plaintext bytes over the cipher text in
place. This works as the cipher text is always larger than the
plaintext, since the plaintext doesn't have a MAC attached.
The amount the perf increase, amount of allocations, and amount of bytes
allocated are pretty nice:
```
benchmark old ns/op new ns/op delta
BenchmarkReadHeaderAndBody-8 88652 75896 -14.39%
benchmark old allocs new allocs delta
BenchmarkReadHeaderAndBody-8 6 4 -33.33%
benchmark old bytes new bytes delta
BenchmarkReadHeaderAndBody-8 65664 128 -99.81%
```
Here old is without this change, and new with it.
This commit exposes the WriteMessage and Flush interfaces of the
underlying brontide.Machine, such that callers can have greater
flexibility in when blocking network operations take place.
This commit modifies WriteMessage to only perform encryption on the
passed plaintext, and buffer the ciphertext within the connection
object. We then modify internal uses of WriteMessage to follow with a
call to Flush, which actually writes the message to the wire.
Additionally, since WriteMessage does not actually perform the write
itself, the io.Writer argument is removed from the function signature
and all call sites.
This commit adds a Flush method to the brontide.Machine, which can write
out a buffered message to an io.Writer. This is a preliminary change
which will allow the encryption of the plaintext to be done in a
distinct method from actually writing the bytes to the wire.
In this commit, we reduce the total number of allocations that a
brontide session will incur over its lifetime. Profiling on one of my
nodes showed that we were generating a lot of garbage due to
re-creating a 65KB buffer to read the next message each time the
ReadMessage method was called.
To reduce the total number of memory allocations, we’ll now simply
re-use a buffer for both the cipher text header, and the cipher text
itself.
