1 files changed, 24 insertions, 0 deletions
diff --git a/tvix/nar-bridge/pkg/http/util.go b/tvix/nar-bridge/pkg/http/util.go
new file mode 100644
index 0000000000..60febea1f4
--- /dev/null
+++ b/tvix/nar-bridge/pkg/http/util.go
@@ -0,0 +1,24 @@
+package http
+
+import (
+	"fmt"
+	nixhash "github.com/nix-community/go-nix/pkg/hash"
+)
+
+// parseNarHashFromUrl parses a nixbase32 string representing a sha256 NarHash
+// and returns a nixhash.Hash when it was able to parse, or an error.
+func parseNarHashFromUrl(narHashFromUrl string) (*nixhash.Hash, error) {
+	// peek at the length. If it's 52 characters, assume sha256,
+	// if it's something else, this is an error.
+	l := len(narHashFromUrl)
+	if l != 52 {
+		return nil, fmt.Errorf("invalid length of narHash: %v", l)
+	}
+
+	nixHash, err := nixhash.ParseNixBase32("sha256:" + narHashFromUrl)
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse nixbase32 hash: %w", err)
+	}
+
+	return nixHash, nil
+}