refactor-for-testability (#3)

Co-authored-by: jdl <jdl@desktop>
Co-authored-by: jdl <jdl@crumpington.com>
Reviewed-on: #3

peer/globals.go

@@ -0,0 +1,37 @@
+package peer
+
+import (
+	"net"
+	"net/netip"
+	"time"
+)
+
+const (
+	version = 1
+
+	bufferSize = 1536
+
+	if_mtu       = 1200
+	if_queue_len = 2048
+
+	controlCipherOverhead = 16
+	dataCipherOverhead    = 16
+	signOverhead          = 64
+
+	pingInterval                  = 8 * time.Second
+	timeoutInterval               = 30 * time.Second
+	broadcastInterval             = 16 * time.Second
+	broadcastErrorTimeoutInterval = 8 * time.Second
+)
+
+var multicastAddr = net.UDPAddrFromAddrPort(netip.AddrPortFrom(
+	netip.AddrFrom4([4]byte{224, 0, 0, 157}),
+	4560))
+
+func newBuf() []byte {
+	return make([]byte, bufferSize)
+}
+
+type marshaller interface {
+	Marshal([]byte) []byte
+}