github.com/braveheart12/insolar-09-08-19@v0.8.7/network/controller/bootstrap/session_manager.go

/*
 * The Clear BSD License
 *
 * Copyright (c) 2019 Insolar Technologies
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted (subject to the limitations in the disclaimer below) provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 *  Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 *  Neither the name of Insolar Technologies nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
 *
 * NO EXPRESS OR IMPLIED LICENSES TO ANY PARTY'S PATENT RIGHTS ARE GRANTED BY THIS LICENSE. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

package bootstrap

import (
	"context"
	"fmt"
	"sort"
	"sync"
	"sync/atomic"
	"time"

	"github.com/insolar/insolar/component"
	"github.com/insolar/insolar/core"
	"github.com/insolar/insolar/instrumentation/inslogger"
	"github.com/insolar/insolar/network/utils"
	"github.com/pkg/errors"
)

type SessionID uint64

//go:generate stringer -type=SessionState
type SessionState uint8

const (
	Authorized SessionState = iota + 1
	Challenge1
	Challenge2
)

const (
	stateRunning = uint32(iota + 1)
	stateIdle
)

type Session struct {
	NodeID core.RecordRef
	Cert   core.AuthorizationCertificate
	State  SessionState

	DiscoveryNonce Nonce

	Time time.Time
	TTL  time.Duration
}

func (s *Session) expirationTime() time.Time {
	return s.Time.Add(s.TTL)
}

type sessionWithID struct {
	*Session
	SessionID
}

type notification struct{}

type SessionManager interface {
	component.Starter
	component.Stopper

	NewSession(ref core.RecordRef, cert core.AuthorizationCertificate, ttl time.Duration) SessionID
	CheckSession(id SessionID, expected SessionState) error
	SetDiscoveryNonce(id SessionID, discoveryNonce Nonce) error
	GetChallengeData(id SessionID) (core.AuthorizationCertificate, Nonce, error)
	ChallengePassed(id SessionID) error
	ReleaseSession(id SessionID) (*Session, error)
	ProlongateSession(id SessionID, session *Session)
}

type sessionManager struct {
	sequence uint64
	lock     sync.RWMutex
	sessions map[SessionID]*Session
	state    uint32

	newSessionNotification  chan notification
	stopCleanupNotification chan notification
}

func NewSessionManager() SessionManager {
	return &sessionManager{
		sessions:                make(map[SessionID]*Session),
		newSessionNotification:  make(chan notification),
		stopCleanupNotification: make(chan notification),
		state:                   stateIdle,
	}
}

func (sm *sessionManager) Start(ctx context.Context) error {
	logger := inslogger.FromContext(ctx)
	logger.Debug("[ sessionManager::Start ] start cleaning up sessions")

	if atomic.CompareAndSwapUint32(&sm.state, stateIdle, stateRunning) {
		go sm.cleanupExpiredSessions()
	} else {
		logger.Warn("[ sessionManager::Start ] Called twice")
	}

	return nil
}

func (sm *sessionManager) Stop(ctx context.Context) error {
	logger := inslogger.FromContext(ctx)
	logger.Debug("[ sessionManager::Stop ] stop cleaning up sessions")

	if atomic.CompareAndSwapUint32(&sm.state, stateRunning, stateIdle) {
		sm.stopCleanupNotification <- notification{}
	} else {
		logger.Warn("[ sessionManager::Stop ] Called twice")
	}

	return nil
}

func (sm *sessionManager) NewSession(ref core.RecordRef, cert core.AuthorizationCertificate, ttl time.Duration) SessionID {
	id := utils.AtomicLoadAndIncrementUint64(&sm.sequence)
	session := &Session{
		NodeID: ref,
		State:  Authorized,
		Cert:   cert,
		Time:   time.Now(),
		TTL:    ttl,
	}
	sessionID := SessionID(id)
	sm.addSession(sessionID, session)
	return sessionID
}

func (sm *sessionManager) addSession(id SessionID, session *Session) {
	sm.lock.Lock()
	sm.sessions[id] = session
	sm.lock.Unlock()

	sm.newSessionNotification <- notification{}
}

func (sm *sessionManager) CheckSession(id SessionID, expected SessionState) error {
	sm.lock.RLock()
	defer sm.lock.RUnlock()

	_, err := sm.checkSession(id, expected)
	return err
}

func (sm *sessionManager) checkSession(id SessionID, expected SessionState) (*Session, error) {
	session := sm.sessions[id]
	if session == nil {
		return nil, errors.New(fmt.Sprintf("no such session ID: %d", id))
	}
	if session.State != expected {
		return nil, errors.New(fmt.Sprintf("session %d should have state %s but has %s", id, expected, session.State))
	}
	return session, nil
}

func (sm *sessionManager) SetDiscoveryNonce(id SessionID, discoveryNonce Nonce) error {
	sm.lock.Lock()
	defer sm.lock.Unlock()

	session, err := sm.checkSession(id, Authorized)
	if err != nil {
		return err
	}
	session.DiscoveryNonce = discoveryNonce
	session.State = Challenge1
	return nil
}

func (sm *sessionManager) GetChallengeData(id SessionID) (core.AuthorizationCertificate, Nonce, error) {
	sm.lock.Lock()
	defer sm.lock.Unlock()

	session, err := sm.checkSession(id, Challenge1)
	if err != nil {
		return nil, nil, err
	}
	return session.Cert, session.DiscoveryNonce, nil
}

func (sm *sessionManager) ChallengePassed(id SessionID) error {
	sm.lock.Lock()
	defer sm.lock.Unlock()

	session, err := sm.checkSession(id, Challenge1)
	if err != nil {
		return err
	}
	session.State = Challenge2
	return nil
}

func (sm *sessionManager) ReleaseSession(id SessionID) (*Session, error) {
	sm.lock.Lock()
	defer sm.lock.Unlock()

	session, err := sm.checkSession(id, Challenge2)
	if err != nil {
		return nil, err
	}
	delete(sm.sessions, id)
	return session, nil
}

func (sm *sessionManager) ProlongateSession(id SessionID, session *Session) {
	session.Time = time.Now()
	sm.addSession(id, session)
}

func (sm *sessionManager) cleanupExpiredSessions() {
	var sessionsByExpirationTime []*sessionWithID
	for {
		sm.lock.RLock()
		sessionsCount := len(sm.sessions)
		sm.lock.RUnlock()

		// We missed notification
		if sessionsCount != 0 && len(sessionsByExpirationTime) == 0 {
			sessionsByExpirationTime = sm.sortSessionsByExpirationTime()
		}

		// Session count is zero - wait for first session added.
		if len(sessionsByExpirationTime) == 0 {
			// Have no active sessions.
			// Block until sessions will be added or session manager begins to stop.
			select {
			case <-sm.newSessionNotification:
				sessionsByExpirationTime = sm.sortSessionsByExpirationTime()
			case <-sm.stopCleanupNotification:
				return
			}

			// Check session instantly released concurrently
			if len(sessionsByExpirationTime) == 0 {
				continue
			}
		}

		// Get expiration time for next session and wait for it
		nextSessionToExpire := sessionsByExpirationTime[0]
		waitTime := time.Until(nextSessionToExpire.expirationTime())

		select {
		case <-sm.newSessionNotification:
			// Handle new session. reorder expiration short list
			sessionsByExpirationTime = sm.sortSessionsByExpirationTime()

		case <-time.After(waitTime):
			// Move forward through sessions and check whether we should delete the session
			sessionsByExpirationTime = sm.expireSessions(sessionsByExpirationTime)

		case <-sm.stopCleanupNotification:
			return
		}
	}
}

func (sm *sessionManager) sortSessionsByExpirationTime() []*sessionWithID {
	sm.lock.RLock()

	// Read active session with their ids. We have to store them as a slice to keep ordering by expiration time.
	sessionsByExpirationTime := make([]*sessionWithID, 0, len(sm.sessions))
	for sessionID, session := range sm.sessions {
		sessionsByExpirationTime = append(sessionsByExpirationTime, &sessionWithID{
			SessionID: sessionID,
			Session:   session,
		})
	}

	sm.lock.RUnlock()

	sort.SliceStable(sessionsByExpirationTime, func(i, j int) bool {
		expirationTime1 := sessionsByExpirationTime[i].expirationTime()
		expirationTime2 := sessionsByExpirationTime[j].expirationTime()

		return expirationTime1.Before(expirationTime2)
	})

	return sessionsByExpirationTime
}

func (sm *sessionManager) expireSessions(sessionsByExpirationTime []*sessionWithID) []*sessionWithID {
	var shift int

	sm.lock.Lock()

	for i, session := range sessionsByExpirationTime {
		// Check when we have to stop expire
		if session.expirationTime().After(time.Now()) {
			break
		}

		delete(sm.sessions, session.SessionID)
		shift = i + 1
	}

	sm.lock.Unlock()

	return sessionsByExpirationTime[shift:]
}