mbirth/gcd-parser
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Detect trailing data (signed firmwares) and print a warning.

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This commit is contained in:
Markus Birth 2019-07-04 23:42:47 +02:00
parent 5ca2f8cad5
commit 7d884a526a
Signed by: mbirth
GPG Key ID: A9928D7A098C3A9A
1 changed files with 16 additions and 3 deletions
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19
grmn/gcd.py
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@ -6,6 +6,7 @@ from .chksum import ChkSum
from .tlv import TLV, TLV6, TLV7, TLVbinary
from struct import unpack
import configparser
import os
import sys
GCD_SIG = b"G\x41RM\x49Nd\00"
@ -25,7 +26,10 @@ class Gcd:
def __init__(self, filename: str=None):
self.filename = filename
self.struct = []
self.is_truncated = False
self.has_trailing = False
if filename is not None:
self.file_len = os.path.getsize(self.filename)
self.load()
def load(self):
@ -41,6 +45,7 @@ class Gcd:
cur_offset = f.tell()
header = f.read(4)
if len(header) < 4:
self.is_truncated = True
#raise ParseException("File truncated. End marker not reached yet.")
print(RED + "WARNING: File truncated. End marker not reached yet. (pos={})".format(f.tell()) + RESET, file=sys.stderr)
break
@ -48,7 +53,7 @@ class Gcd:
tlv = TLV.factory(type_id, length, offset=cur_offset)
self.add_tlv(tlv)
if tlv.type_id == 0xFFFF:
# End of file reached
# End of TLV structure reached
break
tlength = tlv.length
payload = f.read(tlength)
@ -60,6 +65,10 @@ class Gcd:
last_tlv7 = tlv
elif tlv.is_binary:
tlv.set_tlv7(last_tlv7)
self.end_offset = f.tell()
self.trailing_bytes = self.file_len - self.end_offset
if (self.trailing_bytes > 0):
self.has_trailing = True
f.close()
def add_tlv(self, new_tlv: TLV):
@ -67,7 +76,7 @@ class Gcd:
def print_struct(self):
"""
Prints the structure of the parsed GCD file
Prints the structure of the parsed GCD file with compact format for binary data.
"""
last_tlv = 0xffff
tlv_count = 0
@ -84,13 +93,17 @@ class Gcd:
if tlv.length is not None:
tlv_length += tlv.length
last_tlv = tlv.type_id
if (self.has_trailing):
print(RED + "WARNING: {} trailing Bytes. Probably a signed firmware.".format(self.trailing_bytes) + RESET, file=sys.stderr)
def print_struct_full(self):
"""
Prints the structure of the parsed GCD file
Prints the detailed structure of the parsed GCD file
"""
for i, tlv in enumerate(self.struct):
print("#{:03d}: {}".format(i, tlv))
if (self.has_trailing):
print(RED + "WARNING: {} trailing Bytes. Probably a signed firmware.".format(self.trailing_bytes) + RESET, file=sys.stderr)
def validate(self, print_stats: bool=False):
"""