Brief description
pcapng reader cannot read pipe
Scapy version
master (a795ad6)
Python version
3.10
Operating system
Linux 5.15.39+
Additional environment information
No response
How to reproduce
python -c "rdpcap('/dev/stdin')" <a.pcapng is OK, but cat a.pcapng | python -c "rdpcap('/dev/stdin')" fails.
python -c "from scapy.all import *; wrpcapng('a.pcapng', [Ether()])"
xxd a.pcapng
#00000000: 0a0d 0d0a 1c00 0000 4d3c 2b1a 0100 0000 ........M<+.....
#00000010: ffff ffff ffff ffff 1c00 0000 0100 0000 ................
#00000020: 1400 0000 0100 0000 0000 0400 1400 0000 ................
#00000030: 0600 0000 3000 0000 0000 0000 9119 0600 ....0...........
#00000040: 36d7 0f87 0e00 0000 0e00 0000 ffff ffff 6...............
#00000050: ffff 34cf f6f3 9364 9000 0000 3000 0000 ..4....d....0...
python -c "from scapy.all import *; rdpcap('/dev/stdin')" <a.pcapng # ok
cat a.pcapng | python -c "from scapy.all import *; rdpcap('/dev/stdin')" # error!
#Traceback (most recent call last):
# File "<string>", line 1, in <module>
# File "/home/wsh/qpy/scapy/scapy/utils.py", line 1355, in rdpcap
# with PcapReader(filename) as fdesc: # type: ignore
# File "/home/wsh/qpy/scapy/scapy/utils.py", line 1397, in __call__
# raise Scapy_Exception(
#scapy.error.Scapy_Exception: No data could be read!This is because the first some bytes (0a 0d 0d 0a 1c ...) are discarded in try: gzip.open().read(4) when the file is a pipe:
try:
fdesc = gzip.open(filename, "rb") # type: _ByteStream
magic = fdesc.read(4) # raises IOError
except IOError:
fdesc = open(filename, "rb")
# <a.pcapng : /dev/stdin is a regular file, magic = b'\n\r\r\n' (0a 0d 0d 0a), ok
# cat a.pcapng | : /dev/stdin is a pipe, magic = b'6\x00\x00\x00' (06 00 00 00) -- it's at 00000030: in xxd above. the first 0x30 bytes are discarded in gzip.open().read()!
magic = fdesc.read(4)Actual result
No response
Expected result
No response
Related resources
No response
Brief description
pcapng reader cannot read pipe
Scapy version
master (a795ad6)
Python version
3.10
Operating system
Linux 5.15.39+
Additional environment information
No response
How to reproduce
python -c "rdpcap('/dev/stdin')" <a.pcapngis OK, butcat a.pcapng | python -c "rdpcap('/dev/stdin')"fails.This is because the first some bytes (0a 0d 0d 0a 1c ...) are discarded in
try: gzip.open().read(4)when the file is a pipe:scapy/scapy/utils.py
Line 1431 in a795ad6
Actual result
No response
Expected result
No response
Related resources
No response