test(agentcompat): add integration scenarios

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/scenario/legacy_fm_protocol.go

@@ -0,0 +1,115 @@
+//go:build linux
+
+package scenario
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+
+	"github.com/nezhahq/nezha/integration/agentcompat/internal/fixture"
+)
+
+var (
+	errLegacyFMInvalidFrame = errors.New("legacy FM invalid frame")
+	errLegacyFMUnexpected   = errors.New("legacy FM unexpected frame")
+)
+
+type legacyFMRemoteError struct{}
+
+func (legacyFMRemoteError) Error() string { return "legacy FM agent error" }
+
+var errLegacyFMRemote = legacyFMRemoteError{}
+
+const (
+	legacyFMListOp     byte = 0x00
+	legacyFMDownloadOp byte = 0x01
+	legacyFMUploadOp   byte = 0x02
+)
+
+type legacyFMEntry struct {
+	Name string
+	Dir  bool
+}
+
+type legacyFMList struct {
+	Path    string
+	Entries []legacyFMEntry
+}
+
+type legacyFMDownloadHeader struct {
+	Size uint64
+}
+
+func buildLegacyFMList(path fixture.AgentPath) []byte {
+	return append([]byte{legacyFMListOp}, []byte(path.String())...)
+}
+
+func buildLegacyFMUpload(path fixture.AgentPath, size uint64) []byte {
+	frame := make([]byte, 1+8+len(path.String()))
+	frame[0] = legacyFMUploadOp
+	binary.BigEndian.PutUint64(frame[1:9], size)
+	copy(frame[9:], path.String())
+	return frame
+}
+
+func buildLegacyFMDownload(path fixture.AgentPath) []byte {
+	return append([]byte{legacyFMDownloadOp}, []byte(path.String())...)
+}
+
+func parseLegacyFMList(frame []byte) (legacyFMList, error) {
+	if message, ok := parseLegacyFMError(frame); ok {
+		return legacyFMList{}, message
+	}
+	if len(frame) < 8 || !bytes.Equal(frame[:4], []byte("NZFN")) {
+		return legacyFMList{}, errLegacyFMInvalidFrame
+	}
+	pathSize := binary.BigEndian.Uint32(frame[4:8])
+	if pathSize == 0 || uint64(pathSize)+8 > uint64(len(frame)) {
+		return legacyFMList{}, errLegacyFMInvalidFrame
+	}
+	pathEnd := 8 + int(pathSize)
+	result := legacyFMList{Path: string(frame[8:pathEnd])}
+	for cursor := pathEnd; cursor < len(frame); {
+		if len(frame)-cursor < 2 {
+			return legacyFMList{}, errLegacyFMInvalidFrame
+		}
+		entrySize := int(frame[cursor+1])
+		if entrySize == 0 || cursor+2+entrySize > len(frame) || frame[cursor] > 1 {
+			return legacyFMList{}, errLegacyFMInvalidFrame
+		}
+		result.Entries = append(result.Entries, legacyFMEntry{
+			Name: string(frame[cursor+2 : cursor+2+entrySize]),
+			Dir:  frame[cursor] == 1,
+		})
+		cursor += 2 + entrySize
+	}
+	return result, nil
+}
+
+func parseLegacyFMDownload(frame []byte) (legacyFMDownloadHeader, error) {
+	if message, ok := parseLegacyFMError(frame); ok {
+		return legacyFMDownloadHeader{}, message
+	}
+	if len(frame) != 12 || !bytes.Equal(frame[:4], []byte("NZTD")) {
+		return legacyFMDownloadHeader{}, errLegacyFMInvalidFrame
+	}
+	return legacyFMDownloadHeader{Size: binary.BigEndian.Uint64(frame[4:12])}, nil
+}
+
+func parseLegacyFMError(frame []byte) (error, bool) {
+	if len(frame) < 4 || !bytes.Equal(frame[:4], []byte("NERR")) {
+		return nil, false
+	}
+	return errLegacyFMRemote, true
+}
+
+func requireLegacyFMMarker(frame []byte, marker string) error {
+	if message, ok := parseLegacyFMError(frame); ok {
+		return message
+	}
+	if !bytes.Equal(frame, []byte(marker)) {
+		return errLegacyFMUnexpected
+	}
+	return nil
+}