1 files changed, 85 insertions, 0 deletions
diff --git a/internal/server/session/session.go b/internal/server/session/session.go
new file mode 100644
index 0000000..ff56780
--- /dev/null
+++ b/internal/server/session/session.go
@@ -0,0 +1,85 @@
+package session
+
+import (
+	"context"
+	"crypto/ed25519"
+	"crypto/rand"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/kyren223/eko/internal/packet"
+	"github.com/kyren223/eko/pkg/assert"
+	"github.com/kyren223/eko/pkg/snowflake"
+)
+
+type SessionManager interface {
+	AddSession(session *Session)
+	RemoveSession(id snowflake.ID)
+	Session(id snowflake.ID) (session *Session, ok bool)
+
+	Node() *snowflake.Node
+}
+
+type Session struct {
+	// Channel to directly write packets to the cient.
+	// Can be nil in cases where the connection is not available.
+	WriteQueue chan packet.Packet
+	PubKey     ed25519.PublicKey
+
+	manager SessionManager
+	addr    *net.TCPAddr
+	id      snowflake.ID
+
+	mu         sync.Mutex
+	challenge  []byte
+	issuedTime time.Time
+}
+
+func NewSession(manager SessionManager, addr *net.TCPAddr, id snowflake.ID, pubKey ed25519.PublicKey) *Session {
+	session := &Session{
+		manager:    manager,
+		addr:       addr,
+		PubKey:     pubKey,
+		WriteQueue: make(chan packet.Packet, 10),
+		challenge:  make([]byte, 32), // Recommended nonce size
+	}
+	session.Challenge() // Make sure an initial nonce is generated
+	return session
+}
+
+func (s *Session) Addr() *net.TCPAddr {
+	return s.addr
+}
+
+func (s *Session) ID() snowflake.ID {
+	return s.id
+}
+
+func (s *Session) Manager() SessionManager {
+	return s.manager
+}
+
+func (s *Session) Challenge() []byte {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if time.Since(s.issuedTime) > time.Minute {
+		s.issuedTime = time.Now()
+		_, err := rand.Read(s.challenge)
+		assert.NoError(err, "random should always produce a value")
+	}
+	return s.challenge
+}
+
+type key struct{}
+
+var sessKey key
+
+func NewContext(ctx context.Context, sess *Session) context.Context {
+	return context.WithValue(ctx, sessKey, sess)
+}
+
+func FromContext(ctx context.Context) (*Session, bool) {
+	sess, ok := ctx.Value(sessKey).(*Session)
+	return sess, ok
+}