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-rw-r--r--nest/a-path.c38
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;
+}