urlutil: add time validation functions (#3776)

internal/urlutil/time.go

@@ -0,0 +1,43 @@
+package urlutil
+
+import (
+	"fmt"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+// BuildTimeParameters adds the issued and expiry timestamps to the query parameters.
+func BuildTimeParameters(params url.Values, expiry time.Duration) {
+	now := time.Now()
+
+	params.Set(QueryIssued, fmt.Sprint(now.UnixMilli()))
+	params.Set(QueryExpiry, fmt.Sprint(now.Add(expiry).UnixMilli()))
+}
+
+// ValidateTimeParameters validates that the issued and expiry timestamps in the query parameters are valid.
+func ValidateTimeParameters(params url.Values) error {
+	now := time.Now()
+
+	issuedMS, err := strconv.ParseInt(params.Get(QueryIssued), 10, 64)
+	if err != nil {
+		return fmt.Errorf("invalid issued timestamp: %w", err)
+	}
+	issued := time.UnixMilli(issuedMS)
+
+	if now.Add(DefaultLeeway).Before(issued) {
+		return ErrIssuedInTheFuture
+	}
+
+	expiryMS, err := strconv.ParseInt(params.Get(QueryExpiry), 10, 64)
+	if err != nil {
+		return fmt.Errorf("invalid expiry timestamp: %w", err)
+	}
+	expiry := time.UnixMilli(expiryMS)
+
+	if now.Add(-DefaultLeeway).After(expiry) {
+		return ErrExpired
+	}
+
+	return nil
+}