MakeCipherEntry constructs a CipherEntry.

MakeTestCiphers creates a CipherList containing one fresh AEAD cipher for each secret in `secrets`.

NewCipherList creates an empty CipherList.

NewReplayCache returns a fresh ReplayCache that promises to remember at least the most recent `capacity` handshakes.

NewServerSaltGenerator returns a SaltGenerator whose output is apparently random, but is secretly marked as being issued by the server.

NewTCPService creates a TCPService `replayCache` is a pointer to SSServer.replayCache, to share the cache among all ports.

NewUDPService creates a UDPService.

MaxCapacity is the largest allowed size of ReplayCache.

Must be less than or equal to SHA1.Size().

2B length field in UDP header includes header length.

RandomServerSaltGenerator is a basic ServerSaltGenerator.

CipherEntry holds a Cipher with an identifier.

ReplayCache allows us to check whether a handshake salt was used within the last `capacity` handshakes.

CipherList is a thread-safe collection of CipherEntry elements that allows for snapshotting and moving to front.

ServerSaltGenerator offers the ability to check if a salt was marked as server-originated.

TCPService is a Shadowsocks TCP service that can be started and stopped.

UDPService is a running UDP shadowsocks proxy that can be stopped.