add rpc skeleton

internal/gotelem/rpc.go

@@ -0,0 +1,84 @@
+package gotelem
+
+import "github.com/tinylib/msgp/msgp"
+
+// this file is a simple implementation of the msgpack-rpc data format.
+
+type RPCType int
+
+const (
+	RequestType      RPCType = 0
+	ResponseType     RPCType = 1
+	NotificationType RPCType = 2
+)
+
+//go:generate msgp
+//msgp:tuple Request
+//msgp:tuple Response
+//msgp:tuple Notification
+
+// A request is a function call that expects a Response.
+type Request struct {
+	// should always be zero.
+	msgtype int         `msg:"type"`
+	MsgId   uint32      `msg:"msgid"`
+	Method  string      `msg:"method"`
+	Params  interface{} `msg:"params,allownil"`
+}
+
+func NewRequest(msgid uint32, method string, params interface{}) *Request {
+	return &Request{
+		msgtype: 0,
+		MsgId:   msgid,
+		Method:  method,
+		Params:  params,
+	}
+}
+
+// A response is the result of a function call, or an error.
+type Response struct {
+	// should always be one.
+	msgtype int         `msg:"type"`
+	MsgId   uint32      `msg:"msgid"`
+	Error   interface{} `msg:"error,allownil"`
+	Result  interface{} `msg:"result,allownil"`
+}
+
+// A notification is a function call that does not care if the call
+// succeeds and ignores responses.
+type Notification struct {
+	// should always be *2*
+	msgtype int         `msg:"type"`
+	Method  string      `msg:"method"`
+	Params  interface{} `msg:"params,allownil"`
+}
+
+// todo: should these be functions instead, since they're arrays? and we need to determine the type beforehand.
+
+func getMsgType(b []byte) RPCType {
+	size, next, err := msgp.ReadArrayHeaderBytes(b)
+	if err != nil {
+		panic(err)
+	}
+	if size == 3 { // hot path for notifications.
+		return NotificationType
+	}
+
+	vtype, _, err := msgp.ReadIntBytes(next)
+
+	if err != nil {
+		panic(err)
+	}
+
+	// todo: use readIntf instead? returns a []interface{} and we can map it ourselves...
+	return RPCType(vtype)
+}
+
+func parseRPC(raw msgp.Raw) interface{} {
+	t := getMsgType(raw)
+
+	if t == RequestType {
+
+	}
+	return nil
+}