[client,management] Rewrite the SSH feature (#4015)

client/server/jwt_cache.go

@@ -0,0 +1,79 @@
+package server
+
+import (
+	"sync"
+	"time"
+
+	"github.com/awnumar/memguard"
+	log "github.com/sirupsen/logrus"
+)
+
+type jwtCache struct {
+	mu           sync.RWMutex
+	enclave      *memguard.Enclave
+	expiresAt    time.Time
+	timer        *time.Timer
+	maxTokenSize int
+}
+
+func newJWTCache() *jwtCache {
+	return &jwtCache{
+		maxTokenSize: 8192,
+	}
+}
+
+func (c *jwtCache) store(token string, maxAge time.Duration) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.cleanup()
+
+	if c.timer != nil {
+		c.timer.Stop()
+	}
+
+	tokenBytes := []byte(token)
+	c.enclave = memguard.NewEnclave(tokenBytes)
+
+	c.expiresAt = time.Now().Add(maxAge)
+
+	var timer *time.Timer
+	timer = time.AfterFunc(maxAge, func() {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		if c.timer != timer {
+			return
+		}
+		c.cleanup()
+		c.timer = nil
+		log.Debugf("JWT token cache expired after %v, securely wiped from memory", maxAge)
+	})
+	c.timer = timer
+}
+
+func (c *jwtCache) get() (string, bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	if c.enclave == nil || time.Now().After(c.expiresAt) {
+		return "", false
+	}
+
+	buffer, err := c.enclave.Open()
+	if err != nil {
+		log.Debugf("Failed to open JWT token enclave: %v", err)
+		return "", false
+	}
+	defer buffer.Destroy()
+
+	token := string(buffer.Bytes())
+	return token, true
+}
+
+// cleanup destroys the secure enclave, must be called with lock held
+func (c *jwtCache) cleanup() {
+	if c.enclave != nil {
+		c.enclave = nil
+	}
+	c.expiresAt = time.Time{}
+}