add packet validator

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

1 files changed, 39 insertions, 0 deletions

diff --git a/packet/validate.go b/packet/validate.go
new file mode 100644
index 00000000..e3ddf58b
--- /dev/null
+++ b/packet/validate.go
@@ -0,0 +1,39 @@
+package bgp
+
+import (
+	"strconv"
+)
+
+// validator for PathAttribute
+func ValidateFlags(t BGPAttrType, flags uint8) (bool, string) {
+
+	/*
+	 * RFC 4271 P.17 For well-known attributes, the Transitive bit MUST be set to 1.
+	 */
+	if flags&BGP_ATTR_FLAG_OPTIONAL == 0 && flags&BGP_ATTR_FLAG_TRANSITIVE == 0 {
+		eMsg := "well-known attribute must have transitive flag 1"
+		return false, eMsg
+	}
+	/*
+	 * RFC 4271 P.17 For well-known attributes and for optional non-transitive attributes,
+	 * the Partial bit MUST be set to 0.
+	 */
+	if flags&BGP_ATTR_FLAG_OPTIONAL == 0 && flags&BGP_ATTR_FLAG_PARTIAL != 0 {
+		eMsg := "well-known attribute must have partial bit 0"
+		return false, eMsg
+	}
+	if flags&BGP_ATTR_FLAG_OPTIONAL != 0 && flags&BGP_ATTR_FLAG_TRANSITIVE == 0 && flags&BGP_ATTR_FLAG_PARTIAL != 0 {
+		eMsg := "optional non-transitive attribute must have partial bit 0"
+		return false, eMsg
+	}
+
+	// check flags are correct
+
+	if f, ok := pathAttrFlags[t]; ok {
+		if f != flags {
+			eMsg := "flags are invalid. attribtue type : " + strconv.Itoa(int(t))
+			return false, eMsg
+		}
+	}
+	return true, ""
+}