rudp: optimize and refactor

1 files changed, 107 insertions, 0 deletions

diff --git a/rudp/rudp.go b/rudp/rudp.go
new file mode 100644
index 0000000..6b96b56
--- /dev/null
+++ b/rudp/rudp.go
@@ -0,0 +1,107 @@
+/*
+Package rudp implements the low-level Minetest protocol described at
+https://dev.minetest.net/Network_Protocol#Low-level_protocol.
+
+All exported functions and methods in this package are safe for concurrent use
+by multiple goroutines.
+*/
+package rudp
+
+import "encoding/binary"
+
+var be = binary.BigEndian
+
+// protoID must be at the start of every network packet.
+const protoID uint32 = 0x4f457403
+
+// PeerIDs aren't actually used to identify peers, network addresses are,
+// these just exist for backward compatability.
+type PeerID uint16
+
+const (
+	// Used by clients before the server sets their ID.
+	PeerIDNil PeerID = iota
+
+	// The server always has this ID.
+	PeerIDSrv
+
+	// Lowest ID the server can assign to a client.
+	PeerIDCltMin
+)
+
+// ChannelCount is the maximum channel number + 1.
+const ChannelCount = 3
+
+/*
+rawPkt.Data format (big endian):
+
+	rawType
+	switch rawType {
+	case rawTypeCtl:
+		ctlType
+		switch ctlType {
+		case ctlAck:
+			// Tells peer you received a rawTypeRel
+			// and it doesn't need to resend it.
+			seqnum
+		case ctlSetPeerId:
+			// Tells peer to send packets with this Src PeerID.
+			PeerId
+		case ctlPing:
+			// Sent to prevent timeout.
+		case ctlDisco:
+			// Tells peer that you disconnected.
+		}
+	case rawTypeOrig:
+		Pkt.(Data)
+	case rawTypeSplit:
+		// Packet larger than MaxNetPktSize split into smaller packets.
+		// Packets with I >= Count should be ignored.
+		// Once all Count chunks are recieved, they are sorted by I and
+		// concatenated to make a Pkt.(Data).
+		seqnum // Identifies split packet.
+		Count, I uint16
+		Chunk...
+	case rawTypeRel:
+		// Resent until a ctlAck with same seqnum is recieved.
+		// seqnums are sequencial and start at seqnumInit,
+		// These should be processed in seqnum order.
+		seqnum
+		rawPkt.Data
+	}
+*/
+type rawPkt struct {
+	Data  []byte
+	ChNo  uint8
+	Unrel bool
+}
+
+type rawType uint8
+
+const (
+	rawTypeCtl rawType = iota
+	rawTypeOrig
+	rawTypeSplit
+	rawTypeRel
+)
+
+type ctlType uint8
+
+const (
+	ctlAck ctlType = iota
+	ctlSetPeerID
+	ctlPing
+	ctlDisco
+)
+
+type Pkt struct {
+	Data  []byte
+	ChNo  uint8
+	Unrel bool
+}
+
+// seqnums are sequence numbers used to maintain reliable packet order
+// and to identify split packets.
+type seqnum uint16
+
+const seqnumInit seqnum = 65500