feat: implements apis for managing headscale policy (#1792)

hscontrol/db/policy.go

@@ -0,0 +1,44 @@
+package db
+
+import (
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+
+	"errors"
+
+	"github.com/juanfont/headscale/hscontrol/types"
+)
+
+// SetPolicy sets the policy in the database.
+func (hsdb *HSDatabase) SetPolicy(policy string) (*types.Policy, error) {
+	// Create a new policy.
+	p := types.Policy{
+		Data: policy,
+	}
+
+	if err := hsdb.DB.Clauses(clause.Returning{}).Create(&p).Error; err != nil {
+		return nil, err
+	}
+
+	return &p, nil
+}
+
+// GetPolicy returns the latest policy in the database.
+func (hsdb *HSDatabase) GetPolicy() (*types.Policy, error) {
+	var p types.Policy
+
+	// Query:
+	// SELECT * FROM policies ORDER BY id DESC LIMIT 1;
+	if err := hsdb.DB.
+		Order("id DESC").
+		Limit(1).
+		First(&p).Error; err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, types.ErrPolicyNotFound
+		}
+
+		return nil, err
+	}
+
+	return &p, nil
+}