1 files changed, 32 insertions, 0 deletions
diff --git a/trillian.go b/trillian.go
new file mode 100644
index 0000000..e5117da
--- /dev/null
+++ b/trillian.go
@@ -0,0 +1,32 @@
+package stfe
+
+import (
+	"fmt"
+
+	"net/http"
+
+	"github.com/google/trillian"
+	"github.com/google/trillian/types"
+)
+
+// checkGetLeavesByRange does santity-checking on a Trillian response
+func checkGetLeavesByRange(rsp *trillian.GetLeavesByRangeResponse, req GetEntriesRequest) (int, error) {
+	if len(rsp.Leaves) > int(req.End-req.Start+1) {
+		return http.StatusInternalServerError, fmt.Errorf("backend GetLeavesByRange returned too many leaves: %d for [%d,%d]", len(rsp.Leaves), req.Start, req.End)
+	}
+
+	var lr types.LogRootV1
+	if err := lr.UnmarshalBinary(rsp.GetSignedLogRoot().GetLogRoot()); err != nil {
+		return http.StatusInternalServerError, fmt.Errorf("failed unmarshaling log root: %v", err)
+	}
+	if uint64(req.Start) >= lr.TreeSize {
+		return http.StatusBadRequest, fmt.Errorf("invalid start(%d): tree size is %d", req.Start, lr.TreeSize)
+	}
+
+	for i, leaf := range rsp.Leaves {
+		if leaf.LeafIndex != req.Start+int64(i) {
+			return http.StatusInternalServerError, fmt.Errorf("backend GetLeavesByRange returned unexpected leaf index: wanted %d, got %d", req.Start+int64(i), leaf.LeafIndex)
+		}
+	}
+	return 0, nil
+}