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Diffstat (limited to 'include/linux/ppp_defs.h')
-rw-r--r--include/linux/ppp_defs.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/ppp_defs.h b/include/linux/ppp_defs.h
index 9d2b388fae1a..b7e57fdbd413 100644
--- a/include/linux/ppp_defs.h
+++ b/include/linux/ppp_defs.h
@@ -11,4 +11,18 @@
#include <uapi/linux/ppp_defs.h>
#define PPP_FCS(fcs, c) crc_ccitt_byte(fcs, c)
+
+/**
+ * ppp_proto_is_valid - checks if PPP protocol is valid
+ * @proto: PPP protocol
+ *
+ * Assumes proto is not compressed.
+ * Protocol is valid if the value is odd and the least significant bit of the
+ * most significant octet is 0 (see RFC 1661, section 2).
+ */
+static inline bool ppp_proto_is_valid(u16 proto)
+{
+ return !!((proto & 0x0101) == 0x0001);
+}
+
#endif /* _PPP_DEFS_H_ */