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|
package handlers
import (
"context"
"encoding/base64"
"encoding/json"
"fmt"
"strconv"
"strings"
"sync"
"github.com/mimecast/dtail/internal/config"
"github.com/mimecast/dtail/internal/lcontext"
"github.com/mimecast/dtail/internal/omode"
"github.com/mimecast/dtail/internal/session"
)
const (
sessionAckStartOKPrefix = ".syn session start ok"
sessionAckUpdateOKPrefix = ".syn session update ok"
sessionAckErrorPrefix = ".syn session err "
)
type sessionCommandState struct {
mu sync.Mutex
active bool
generation uint64
spec session.Spec
cancel context.CancelFunc
}
func (h *ServerHandler) handleSessionCommand(_ context.Context, _ lcontext.LContext, argc int, args []string, commandFinished func()) {
defer commandFinished()
action, generation, spec, err := parseSessionCommand(args, argc)
if err != nil {
h.send(h.serverMessages, sessionAckErrorPrefix+err.Error())
return
}
switch action {
case "START":
generation, err = h.sessionState.start(h, spec)
if err != nil {
h.send(h.serverMessages, sessionAckErrorPrefix+err.Error())
return
}
h.send(h.serverMessages, fmt.Sprintf("%s %d", sessionAckStartOKPrefix, generation))
case "UPDATE":
if !h.sessionState.activeSession() {
h.send(h.serverMessages, sessionAckErrorPrefix+"session not started")
return
}
generation, err = h.sessionState.update(h, spec, generation)
if err != nil {
h.send(h.serverMessages, sessionAckErrorPrefix+err.Error())
return
}
h.send(h.serverMessages, fmt.Sprintf("%s %d", sessionAckUpdateOKPrefix, generation))
default:
h.send(h.serverMessages, sessionAckErrorPrefix+"unknown action")
}
}
func parseSessionCommand(args []string, argc int) (action string, generation uint64, spec session.Spec, err error) {
if argc < 3 {
return "", 0, spec, fmt.Errorf("invalid SESSION command")
}
action = strings.ToUpper(strings.TrimSpace(args[1]))
payloadIndex := 2
if action == "UPDATE" && argc >= 4 {
generation, err = strconv.ParseUint(args[2], 10, 64)
if err != nil {
return "", 0, spec, fmt.Errorf("invalid session generation")
}
payloadIndex = 3
}
payload, err := base64.StdEncoding.DecodeString(args[payloadIndex])
if err != nil {
return "", 0, spec, fmt.Errorf("invalid session payload")
}
if err := json.Unmarshal(payload, &spec); err != nil {
return "", 0, spec, fmt.Errorf("invalid session spec")
}
if err := validateSessionSpec(spec); err != nil {
return "", 0, spec, err
}
return action, generation, spec, nil
}
func validateSessionSpec(spec session.Spec) error {
switch spec.Mode {
case omode.TailClient, omode.CatClient, omode.GrepClient, omode.MapClient, omode.HealthClient:
default:
return fmt.Errorf("unsupported session mode")
}
if spec.Query != "" && spec.Mode != omode.MapClient && spec.Mode != omode.TailClient {
return fmt.Errorf("query sessions require map or tail mode")
}
if spec.Query == "" && spec.Mode == omode.MapClient {
return fmt.Errorf("missing session query")
}
if err := validateSessionOptions(spec.Options); err != nil {
return err
}
if _, err := spec.Commands(); err != nil {
return fmt.Errorf("invalid session spec")
}
return nil
}
func (s *sessionCommandState) start(handler *ServerHandler, spec session.Spec) (uint64, error) {
commands, err := prepareSessionCommands(spec)
if err != nil {
return 0, err
}
s.mu.Lock()
if s.active {
s.mu.Unlock()
return 0, fmt.Errorf("session already started")
}
ctx, cancel := handler.newCommandContext(context.Background())
s.active = true
s.generation = 1
s.spec = spec
s.cancel = cancel
s.mu.Unlock()
if err := handler.dispatchSessionCommands(ctx, commands); err != nil {
cancel()
s.reset()
return 0, err
}
return 1, nil
}
func (s *sessionCommandState) update(handler *ServerHandler, spec session.Spec, generation uint64) (uint64, error) {
commands, err := prepareSessionCommands(spec)
if err != nil {
return 0, err
}
s.mu.Lock()
if !s.active {
s.mu.Unlock()
return 0, fmt.Errorf("session not started")
}
oldCancel := s.cancel
ctx, cancel := handler.newCommandContext(context.Background())
if generation == 0 {
generation = s.generation + 1
}
s.active = true
s.generation = generation
s.spec = spec
s.cancel = cancel
s.mu.Unlock()
if oldCancel != nil {
oldCancel()
}
if err := handler.dispatchSessionCommands(ctx, commands); err != nil {
cancel()
s.reset()
return 0, err
}
return generation, nil
}
func prepareSessionCommands(spec session.Spec) ([]string, error) {
if spec.Query != "" {
return nil, fmt.Errorf("query sessions not supported yet")
}
commands, err := spec.Commands()
if err != nil {
return nil, fmt.Errorf("invalid session spec")
}
return commands, nil
}
func validateSessionOptions(raw string) error {
if strings.TrimSpace(raw) == "" {
return nil
}
if _, _, err := config.DeserializeOptions(strings.Split(raw, ":")); err != nil {
return fmt.Errorf("invalid session spec")
}
return nil
}
func (s *sessionCommandState) activeSession() bool {
s.mu.Lock()
defer s.mu.Unlock()
return s.active
}
func (s *sessionCommandState) keepAlive() bool {
s.mu.Lock()
defer s.mu.Unlock()
return s.active
}
func (s *sessionCommandState) reset() {
s.mu.Lock()
defer s.mu.Unlock()
s.active = false
s.generation = 0
s.spec = session.Spec{}
s.cancel = nil
}
func (h *ServerHandler) dispatchSessionCommands(ctx context.Context, commands []string) error {
for _, command := range commands {
if err := h.handleRawCommand(ctx, command); err != nil {
return err
}
}
return nil
}
|
