Further drafting of rpc module.

Also: fix typo in model definitions.

model/model.go

@@ -1,14 +1,14 @@
 package model
 
-type Filesytem struct {
+type Filesystem struct {
 	Name      string
-	Children  []Filesytem
+	Children  []Filesystem
 	Snapshots []Snapshot
 }
 
 type FilesytemMapping struct {
-	From Filesytem
+	From Filesystem
-	To   Filesytem
+	To   Filesystem
 }
 
 type Snapshot struct {
@@ -16,7 +16,7 @@ type Snapshot struct {
 }
 
 type Pool struct {
-	Root      Filesytem
+	Root Filesystem
 }
 
 type SSHTransport struct {

rpc/rpc.go

@@ -1,76 +1,165 @@
 package rpc
 
+import (
+	"encoding/json"
+	"io"
+
+	. "github.com/zrepl/zrepl/model"
+	. "github.com/zrepl/zrepl/util"
+)
+
 type RPCRequester interface {
-	FilesystemRequest(r FilesystemRequest) (root model.Filesystem, err error)
+	FilesystemRequest(r FilesystemRequest) (root Filesystem, err error)
-	InitialTransferRequest(r InitialTransferRequest) (io.Read, error)
+	InitialTransferRequest(r InitialTransferRequest) (io.Reader, error)
-	IncrementalTransferRequest(r IncrementalTransferRequest) (io.Read, error)
+	IncrementalTransferRequest(r IncrementalTransferRequest) (io.Reader, error)
 }
 
 type RPCHandler interface {
-	HandleFilesystemRequest(r FilesystemRequest) (root model.Filesystem, err error)
+	HandleFilesystemRequest(r FilesystemRequest) (root Filesystem, err error)
-	HandleInitialTransferRequest(r InitialTransferRequest) (io.Read, error)
+	HandleInitialTransferRequest(r InitialTransferRequest) (io.Reader, error)
-	HandleIncrementalTransferRequestRequest(r IncrementalTransferRequest) (io.Read, error)
+	HandleIncrementalTransferRequest(r IncrementalTransferRequest) (io.Reader, error)
 }
 
+const ByteStreamRPCProtocolVersion = 1
 
 type ByteStreamRPC struct {
-	conn   io.ReadWriteCloser
+	conn    io.ReadWriteCloser
+	encoder *json.Encoder
+	decoder *json.Decoder
 }
 
 func ConnectByteStreamRPC(conn io.ReadWriteCloser) (ByteStreamRPC, error) {
 	// TODO do ssh connection to transport, establish TCP-like communication channel
-	conn := sshtransport.New()
 	rpc := ByteStreamRPC{
-		conn: conn,
+		conn:    conn,
+		encoder: json.NewEncoder(conn),
+		decoder: json.NewDecoder(conn),
 	}
-	return conn, nil
+
+	// Assert protocol versions are equal
+	req := NewByteStreamRPCProtocolVersionRequest()
+	rpc.encoder.Encode(&req)
+	return rpc, nil
 }
 
-func ListenByteStreamRPC(conn io.ReadWriteCloser, handler RPCHandler) (error) {
+func ListenByteStreamRPC(conn io.ReadWriteCloser, handler RPCHandler) error {
-	// Read from connection, decode wire protocol, route requests to handler
+
+	// A request consists of two subsequent JSON objects
+	// Object 1: RequestHeader => contains type of Request Body
+	// Object 2: RequestBody, e.g. IncrementalTransferRequest
+	// A response is always a ResponseHeader followed by bytes to be interpreted
+	// 	as indicated by the ResponseHeader.ResponseType, e.g.
+	// 	 a) a chunked response
+	//   b) or another JSON object
+
+	decoder := json.NewDecoder(conn)
+	encoder := json.NewEncoder(conn)
+
+	for {
+
+		var header RequestHeader = RequestHeader{}
+		if err := decoder.Decode(&header); err != nil {
+			respondWithError(conn, EDecodeHeader, err)
+			conn.Close()
+			return err
+		}
+
+		switch header.Type {
+		case RTProtocolVersionRequest:
+			var rq ByteStreamRPCProtocolVersionRequest
+			if err := decoder.Decode(&rq); err != nil {
+				respondWithError(conn, EDecodeRequestBody, nil)
+				conn.Close()
+			}
+
+			if rq.ClientVersion != ByteStreamRPCProtocolVersion {
+				respondWithError(conn, EProtocolVersionMismatch, nil)
+				conn.Close()
+			}
+
+			r := ResponseHeader{
+				RequestId: header.Id,
+			}
+			if err := encoder.Encode(&r); err != nil {
+				return err
+			}
+
+		case RTFilesystemRequest:
+			var rq FilesystemRequest
+			if err := decoder.Decode(&rq); err != nil {
+				respondWithError(conn, EDecodeRequestBody, nil)
+				conn.Close()
+			}
+
+			roots, err := handler.HandleFilesystemRequest(rq)
+			if err != nil {
+				respondWithError(conn, EHandler, err)
+			} else {
+				if err := encoder.Encode(&roots); err != nil {
+					return err
+				}
+			}
+
+		case RTInitialTransferRequest:
+			var rq InitialTransferRequest
+			if err := decoder.Decode(&rq); err != nil {
+				respondWithError(conn, EDecodeRequestBody, nil)
+			}
+
+			snapReader, err := handler.HandleInitialTransferRequest(rq)
+			if err != nil {
+				respondWithError(conn, EHandler, err)
+			} else {
+				chunker := NewChunker(snapReader)
+				_, err := io.Copy(conn, &chunker)
+				if err != nil {
+					return err
+				}
+			}
+		// TODO
+		default:
+			respondWithError(conn, EUnknownRequestType, nil)
+			conn.Close()
+		}
+	}
+
 	return nil
 }
 
-func (c ByteStreamRPC) FilesystemRequest(r FilesystemRequest) (roots []model.Filesystem, err error) {
+func respondWithError(conn io.Writer, id ErrorId, err error) error {
-	encodedReader := protobuf.Encode(r)
+	return nil
-	c.conn.Write(NewChunker(encodedReader))
-	encodedResponseReader := NewUnchunker(c.conn.Read())
-	roots = protobuf.Decode(encodedResponse)
-	return
 }
 
-func (c ByteStreamRPC) InitialTransferRequest(r InitialTransferRequest) (io.Read, error) {
+func (c ByteStreamRPC) FilesystemRequest(r FilesystemRequest) (roots []Filesystem, err error) {
+	return nil, nil
+}
+
+func (c ByteStreamRPC) InitialTransferRequest(r InitialTransferRequest) (io.Reader, error) {
 	// send request header using protobuf or similar
-	encodedReader := protobuf.Encode(r)
+	return nil, nil
-	c.conn.Write(NewChunker(encodedReader))
-	// expect chunked response -> use unchunker on c.conn to read snapshot stream
-	return NewUmainnchunker(c.conn.Read())
 }
 
-func (c ByteStreamRPC) IncrementalTransferRequest(r IncrementalTransferRequest) (io.Read, error) {
+func (c ByteStreamRPC) IncrementalTransferRequest(r IncrementalTransferRequest) (io.Reader, error) {
-
+	return nil, nil
 }
 
-
 type LocalRPC struct {
 	handler RPCHandler
 }
 
-
 func ConnectLocalRPC(handler RPCHandler) LocalRPC {
 	return LocalRPC{handler}
 }
 
-func (c LocalRPC) FilesystemRequest(r FilesystemRequest) (root model.Filesystem, err error) {
+func (c LocalRPC) FilesystemRequest(r FilesystemRequest) (root Filesystem, err error) {
 	return c.handler.HandleFilesystemRequest(r)
 }
 
-func (c LocalRPC) InitialTransferRequest(r InitialTransferRequest) (io.Read, error) {
+func (c LocalRPC) InitialTransferRequest(r InitialTransferRequest) (io.Reader, error) {
 	return c.handler.HandleInitialTransferRequest(r)
 }
 
-func (c LocalRPC) IncrementalTransferRequest(r IncrementalTransferRequest) (io.Read, error) {
+func (c LocalRPC) IncrementalTransferRequest(r IncrementalTransferRequest) (reader io.Reader, err error) {
-	return c.handler.HandleIncrementalTransferRequest(r)
+	reader, err = c.handler.HandleIncrementalTransferRequest(r)
+	return
 }
-
-

rpc/structs.go

@@ -1,29 +1,76 @@
-package protocol
+package rpc
 
-type RequestId uint8
+import "io"
-type Request struct {
+
-	RequestType RequestType
+type RequestId [16]byte
-	RequestId 	[16]byte // UUID
+type RequestType uint8
+
+const (
+	RTProtocolVersionRequest RequestType = 1
+	RTFilesystemRequest                  = 16
+	RTInitialTransferRequest             = 17
+)
+
+type RequestHeader struct {
+	Type RequestType
+	Id   [16]byte // UUID
 }
 
 type FilesystemRequest struct {
-	Request
 	Roots []string
 }
 
 type InitialTransferRequest struct {
-	Request
 	Snapshot string // tank/my/db@ljlsdjflksdf
 }
+
 func (r InitialTransferRequest) Respond(snapshotReader io.Reader) {
 
 }
 
 type IncrementalTransferRequest struct {
-	Request
 	FromSnapshot string
-	ToSnapshot 	 string
+	ToSnapshot   string
 }
+
 func (r IncrementalTransferRequest) Respond(snapshotReader io.Reader) {
 
 }
+
+type ByteStreamRPCProtocolVersionRequest struct {
+	ClientVersion uint8
+}
+
+type ErrorId uint8
+
+const (
+	ENoError                 ErrorId = 0
+	EDecodeHeader                    = 1
+	EUnknownRequestType              = 2
+	EDecodeRequestBody               = 3
+	EProtocolVersionMismatch         = 4
+	EHandler                         = 5
+)
+
+type ResponseType uint8
+
+const (
+	ROK ResponseType = 0
+)
+
+type ResponseHeader struct {
+	RequestId    RequestId
+	ErrorId      ErrorId
+	Message      string
+	ResponseType ResponseType
+}
+
+func NewByteStreamRPCProtocolVersionRequest() ByteStreamRPCProtocolVersionRequest {
+	return ByteStreamRPCProtocolVersionRequest{
+		ClientVersion: ByteStreamRPCProtocolVersion,
+	}
+}
+
+func newUUID() [16]byte {
+	return [16]byte{}
+}