1 files changed, 38 insertions, 0 deletions
diff --git a/nest/a-path.c b/nest/a-path.c
new file mode 100644
index 0000000..557f29c
--- /dev/null
+++ b/nest/a-path.c
@@ -0,0 +1,38 @@
+/*
+ *	BIRD -- Path Operations
+ *
+ *	(c) 2000 Martin Mares <mj@ucw.cz>
+ *	(c) 2000 Pavel Machek <pavel@ucw.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include "nest/bird.h"
+#include "nest/route.h"
+#include "lib/resource.h"
+#include "lib/unaligned.h"
+
+struct adata *
+as_path_prepend(struct linpool *pool, struct adata *olda, int as)
+{
+  struct adata *newa;
+
+  if (olda->length && olda->data[0] == 2 && olda->data[1] < 255) /* Starting with sequence => just prepend the AS number */
+    {
+      newa = lp_alloc(pool, sizeof(struct adata) + olda->length + 2);
+      newa->length = olda->length + 2;
+      newa->data[0] = 2;
+      newa->data[1] = olda->data[1] + 1;
+      memcpy(newa->data+4, olda->data+2, olda->length-2);
+    }
+  else					/* Create new path segment */
+    {
+      newa = lp_alloc(pool, sizeof(struct adata) + olda->length + 4);
+      newa->length = olda->length + 4;
+      newa->data[0] = 2;
+      newa->data[1] = 1;
+      memcpy(newa->data+4, olda->data, olda->length);
+    }
+  put_u16(newa->data+2, as);
+  return newa;
+}