| diff --git a/scapy/contrib/cdp.py b/scapy/contrib/cdp.py |
| index c8b7f106..7b1ff64d 100644 |
| --- a/scapy/contrib/cdp.py |
| +++ b/scapy/contrib/cdp.py |
| @@ -102,7 +102,8 @@ def _CDPGuessPayloadClass(p, **kargs): |
| class CDPMsgGeneric(Packet): |
| name = "CDP Generic Message" |
| fields_desc = [ XShortEnumField("type", None, _cdp_tlv_types), |
| - FieldLenField("len", None, "val", "!H"), |
| + FieldLenField("len", None, "val", "!H", |
| + adjust=lambda pkt, x: x + 4), |
| StrLenField("val", "", length_from=lambda x:x.len - 4) ] |
| |
| |
| @@ -178,5 +179,6 @@ class CDPMsgAddr(CDPMsgGeneric): |
| class CDPMsgPortID(CDPMsgGeneric): |
| name = "Port ID" |
| fields_desc = [ XShortEnumField("type", 0x0003, _cdp_tlv_types), |
| - FieldLenField("len", None, "iface", "!H"), |
| + FieldLenField("len", None, "iface", "!H", |
| + adjust=lambda pkt, x: x + 4), |
| StrLenField("iface", "Port 1", length_from=lambda x:x.len - 4) ] |
| @@ -319,7 +319,7 @@ class _CDPChecksum: |
| This padding is only used for checksum computation. The original |
| packet should not be altered.""" |
| if len(pkt) % 2: |
| - last_chr = pkt[-1] |
| + last_chr = pkt[len(pkt)-1:] |
| if last_chr <= b'\x80': |
| return pkt[:-1] + b'\x00' + last_chr |
| else: |