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Check that packet length is good

This commit is contained in:
Yohann D'ANELLO 2021-01-05 22:01:49 +01:00
parent eb0098552a
commit 084f512d34
Signed by: ynerant
GPG Key ID: 3A75C55819C8CF85
1 changed files with 8 additions and 1 deletions
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9
squinnondation/messages.py
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@ -492,14 +492,21 @@ class Packet:
pkt.magic = data[0] pkt.magic = data[0]
pkt.version = data[1] pkt.version = data[1]
pkt.body_length = socket.ntohs(int.from_bytes(data[2:4], sys.byteorder)) pkt.body_length = socket.ntohs(int.from_bytes(data[2:4], sys.byteorder))
if len(data) != 4 + pkt.body_length:
raise ValueError(f"Invalid packet length: "
f"declared body length is {pkt.body_length} while {len(data) - 4} bytes are avalaible")
pkt.body = [] pkt.body = []
read_bytes = 0 read_bytes = 0
while read_bytes < min(len(data) - 4, pkt.body_length): while read_bytes < min(len(data) - 4, pkt.body_length):
tlv_type = data[4 + read_bytes] tlv_type = data[4 + read_bytes]
if not (0 <= tlv_type < len(TLV.tlv_classes())): if not (0 <= tlv_type < len(TLV.tlv_classes())):
raise ValueError(f"TLV type is not supported: {tlv_type}") raise ValueError(f"TLV type is not supported: {tlv_type}")
tlv_length = data[4 + read_bytes + 1] if tlv_type > 0 else -1
if 2 + tlv_length > pkt.body_length - read_bytes:
raise ValueError(f"TLV length is too long: requesting {tlv_length} bytes, "
f"remaining {pkt.body_length - read_bytes}")
tlv = TLV.tlv_classes()[tlv_type]() tlv = TLV.tlv_classes()[tlv_type]()
tlv.unmarshal(data[4 + read_bytes:4 + read_bytes + pkt.body_length]) tlv.unmarshal(data[4 + read_bytes:4 + read_bytes + 2 + tlv_length])
pkt.body.append(tlv) pkt.body.append(tlv)
read_bytes += len(tlv) read_bytes += len(tlv)