buffer+pool: add buffer.Read and pool.ReadBuffer

buffer/read.go

@@ -0,0 +1,19 @@
+package buffer
+
+import (
+	"github.com/lightningnetwork/lnd/lnwire"
+)
+
+// ReadSize represents the size of the maximum message that can be read off the
+// wire by brontide. The buffer is used to hold the ciphertext while the
+// brontide state machine decrypts the message.
+const ReadSize = lnwire.MaxMessagePayload + 16
+
+// Read is a static byte array sized to the maximum-allowed Lightning message
+// size, plus 16 bytes for the MAC.
+type Read [ReadSize]byte
+
+// Recycle zeroes the Read, making it fresh for another use.
+func (b *Read) Recycle() {
+	RecycleSlice(b[:])
+}