rudp: optimize and refactor

[mt.git] / rudp / rudp.go

diff --git a/rudp/rudp.go b/rudp/rudp.go
new file mode 100644 (file)
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