feat: add independent platform modules and multi-provider storage

auth/session.go

@@ -0,0 +1,87 @@
+package auth
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"time"
+
+	"git.yuntuo.hk/k2safe/go-omni/cache"
+)
+
+// Sessions stores server-issued opaque bearer credentials as SHA-256 keys.
+// The caller verifies login credentials before Issue; Store owns persistence.
+type Sessions struct {
+	store  cache.Store
+	prefix string
+	ttl    time.Duration
+}
+
+func NewSessions(store cache.Store, prefix string, ttl time.Duration) (*Sessions, error) {
+	if store == nil || len(prefix) > 512 || ttl < time.Second || ttl > 30*24*time.Hour {
+		return nil, errors.New("auth: invalid session configuration")
+	}
+	return &Sessions{store: store, prefix: prefix, ttl: ttl}, nil
+}
+func (s *Sessions) Issue(ctx context.Context, p Principal) (string, error) {
+	if p.UserID == "" || len(p.UserID) > 256 || len(p.TenantID) > 256 {
+		return "", ErrInvalidToken
+	}
+	data, err := json.Marshal(p)
+	if err != nil {
+		return "", err
+	}
+	if len(data) > 16384 {
+		return "", errors.New("auth: session principal too large")
+	}
+	secret := make([]byte, 32)
+	if _, err := rand.Read(secret); err != nil {
+		return "", err
+	}
+	token := base64.RawURLEncoding.EncodeToString(secret)
+	key, _ := s.key(token)
+	if err := s.store.Set(ctx, key, data, s.ttl); err != nil {
+		return "", err
+	}
+	return token, nil
+}
+func (s *Sessions) key(token string) (string, error) {
+	if len(token) != 43 {
+		return "", ErrInvalidToken
+	}
+	b, err := base64.RawURLEncoding.DecodeString(token)
+	if err != nil || len(b) != 32 {
+		return "", ErrInvalidToken
+	}
+	sum := sha256.Sum256(b)
+	return s.prefix + hex.EncodeToString(sum[:]), nil
+}
+func (s *Sessions) Authenticate(ctx context.Context, token string) (Principal, error) {
+	key, err := s.key(token)
+	if err != nil {
+		return Principal{}, err
+	}
+	data, err := s.store.Get(ctx, key)
+	if errors.Is(err, cache.ErrMiss) {
+		return Principal{}, ErrInvalidToken
+	}
+	if err != nil {
+		return Principal{}, err
+	}
+	var p Principal
+	if len(data) > 16384 || json.Unmarshal(data, &p) != nil || p.UserID == "" {
+		return Principal{}, ErrInvalidToken
+	}
+	return p, nil
+}
+func (s *Sessions) Revoke(ctx context.Context, token string) error {
+	key, err := s.key(token)
+	if err != nil {
+		return err
+	}
+	return s.store.Delete(ctx, key)
+}