Initial implementation of file transfer resume

1 files changed, 75 insertions, 0 deletions

diff --git a/hotline/file_resume_data.go b/hotline/file_resume_data.go
new file mode 100644
index 0000000..f5b82de
--- /dev/null
+++ b/hotline/file_resume_data.go
@@ -0,0 +1,75 @@
+package hotline
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+// FileResumeData is sent when a client or server would like to resume a transfer from an offset
+type FileResumeData struct {
+	Format       [4]byte  // "RFLT"
+	Version      [2]byte  // Always 1
+	RSVD         [34]byte // Unused
+	ForkCount    [2]byte  // Length of ForkInfoList.  Either 2 or 3 depending on whether file has a resource fork
+	ForkInfoList []ForkInfoList
+}
+
+type ForkInfoList struct {
+	Fork     [4]byte // "DATA" or "MACR"
+	DataSize [4]byte // offset from which to resume the transfer of data
+	RSVDA    [4]byte // Unused
+	RSVDB    [4]byte // Unused
+}
+
+func NewForkInfoList(b []byte) *ForkInfoList {
+	return &ForkInfoList{
+		Fork:     [4]byte{0x44, 0x41, 0x54, 0x41},
+		DataSize: [4]byte{b[0], b[1], b[2], b[3]},
+		RSVDA:    [4]byte{},
+		RSVDB:    [4]byte{},
+	}
+}
+
+func NewFileResumeData(list []ForkInfoList) *FileResumeData {
+	return &FileResumeData{
+		Format:       [4]byte{0x52, 0x46, 0x4C, 0x54}, // RFLT
+		Version:      [2]byte{0, 1},
+		RSVD:         [34]byte{},
+		ForkCount:    [2]byte{0, uint8(len(list))},
+		ForkInfoList: list,
+	}
+}
+
+func (frd *FileResumeData) BinaryMarshal() ([]byte, error) {
+	var buf bytes.Buffer
+	_ = binary.Write(&buf, binary.LittleEndian, frd.Format)
+	_ = binary.Write(&buf, binary.LittleEndian, frd.Version)
+	_ = binary.Write(&buf, binary.LittleEndian, frd.RSVD)
+	_ = binary.Write(&buf, binary.LittleEndian, frd.ForkCount)
+	for _, fil := range frd.ForkInfoList {
+		_ = binary.Write(&buf, binary.LittleEndian, fil)
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (frd *FileResumeData) UnmarshalBinary(b []byte) error {
+	frd.Format = [4]byte{b[0], b[1], b[2], b[3]}
+	frd.Version = [2]byte{b[4], b[5]}
+	frd.ForkCount = [2]byte{b[40], b[41]}
+
+	for i := 0; i < int(frd.ForkCount[1]); i++ {
+		var fil ForkInfoList
+		start := 42 + i*16
+		end := start + 16
+
+		r := bytes.NewReader(b[start:end])
+		if err := binary.Read(r, binary.BigEndian, &fil); err != nil {
+			return err
+		}
+
+		frd.ForkInfoList = append(frd.ForkInfoList, fil)
+	}
+
+	return nil
+}