Prototype secure ZIP extraction (T-102)

core/installer/limits.go

@@ -0,0 +1,45 @@
+package installer
+
+import (
+	"errors"
+	"fmt"
+	"math"
+)
+
+var ErrInvalidLimits = errors.New("invalid ZIP extraction limits")
+
+const (
+	DefaultMaxEntries           = 10_000
+	DefaultMaxUncompressedBytes = int64(4 * 1024 * 1024 * 1024)
+	DefaultMaxCompressionRatio  = 200.0
+)
+
+// Limits bounds archive metadata and decompressed output.
+type Limits struct {
+	MaxEntries           int
+	MaxUncompressedBytes int64
+	MaxCompressionRatio  float64
+}
+
+func DefaultLimits() Limits {
+	return Limits{
+		MaxEntries:           DefaultMaxEntries,
+		MaxUncompressedBytes: DefaultMaxUncompressedBytes,
+		MaxCompressionRatio:  DefaultMaxCompressionRatio,
+	}
+}
+
+func (limits Limits) validate() error {
+	if limits.MaxEntries <= 0 {
+		return fmt.Errorf("%w: MaxEntries must be positive", ErrInvalidLimits)
+	}
+	if limits.MaxUncompressedBytes <= 0 {
+		return fmt.Errorf("%w: MaxUncompressedBytes must be positive", ErrInvalidLimits)
+	}
+	if limits.MaxCompressionRatio <= 0 ||
+		math.IsNaN(limits.MaxCompressionRatio) ||
+		math.IsInf(limits.MaxCompressionRatio, 0) {
+		return fmt.Errorf("%w: MaxCompressionRatio must be finite and positive", ErrInvalidLimits)
+	}
+	return nil
+}