1 files changed, 52 insertions, 0 deletions
diff --git a/lib/mpls_ntop.c b/lib/mpls_ntop.c
new file mode 100644
index 0000000..f8d89f4
--- /dev/null
+++ b/lib/mpls_ntop.c
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <linux/mpls.h>
+
+#include "utils.h"
+
+static const char *mpls_ntop1(const struct mpls_label *addr, char *buf, size_t buflen)
+{
+	size_t destlen = buflen;
+	char *dest = buf;
+	int count = 0;
+
+	while (1) {
+		uint32_t entry = ntohl(addr[count++].entry);
+		uint32_t label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
+		int len = snprintf(dest, destlen, "%u", label);
+
+		if (len >= destlen)
+			break;
+
+		/* Is this the end? */
+		if (entry & MPLS_LS_S_MASK)
+			return buf;
+
+		dest += len;
+		destlen -= len;
+		if (destlen) {
+			*dest = '/';
+			dest++;
+			destlen--;
+		}
+	}
+	errno = -E2BIG;
+	return NULL;
+}
+
+const char *mpls_ntop(int af, const void *addr, char *buf, size_t buflen)
+{
+	switch(af) {
+	case AF_MPLS:
+		errno = 0;
+		return mpls_ntop1((struct mpls_label *)addr, buf, buflen);
+	default:
+		errno = EAFNOSUPPORT;
+	}
+
+	return NULL;
+}