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The padding and CRC of Ethernet II frames are included in the TCP length
Brief description
The padding and CRC of Ethernet II frames are included in the TCP length, when I tried to get the length of TCP payload with the following code.
with PcapNgReader(pcap_path) as preader:
for p in preader:
ip = p.payload
if not isinstance(ip, scapy.layers.inet.IP):
continue
tcp = ip.payload
p_len = len(tcp.payload) # There is a problem with the value of p_len
Ethernet II specifies that the minimum amount of data is 46 bytes. If it does not meet the requirements, 0 bytes will be filled. Therefore, when the TCP payload is length 0, there will be 6 bytes of padding, and 4 bytes of CRC check code.Here, the value of p_len is 10 instead of the 0.
Scapy version
2.4.5
Python version
3.10
Operating system
Windows 11
Additional environment information
No response
How to reproduce
Useing following code to parse the report.pcapng file in related resources
with PcapNgReader(pcap_path) as preader:
for p in preader:
ip = p.payload
if not isinstance(ip, scapy.layers.inet.IP):
continue
tcp = ip.payload
p_len = len(tcp.payload)
print(p_len)
Actual result
10
Expected result
0
