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| author | Vadim Yanitskiy <axilirator@gmail.com> | 2018-02-20 19:43:02 +0700 |
|---|---|---|
| committer | Vadim Yanitskiy <axilirator@gmail.com> | 2018-02-20 19:43:02 +0700 |
| commit | 318f8b78aad5961eba6b179f84e772bff759ade3 (patch) | |
| tree | 579a991dff3f717b40b222039030a2ea3efe56c6 /src | |
| parent | d406afd23e5e0efb38a11bd40a7ff6f0a01ee7f6 (diff) | |
fake_trx/data_dump.py: use 2 bytes to store message length
One byte may store a value in range [0x00, 0xff]. The maximal 0xff
value is 255 in dec, so a message length is limited to 255 bytes.
This is enough for GSM bursts, but not for EDGE.
Since this change, two bytes of header are used to store the
pending message length. All captures created before are not
supported anymore...
Change-Id: I5a69d5cf2914fe56b2f9acca6054c9470627f91e
Diffstat (limited to 'src')
| -rw-r--r-- | src/target/fake_trx/data_dump.py | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/src/target/fake_trx/data_dump.py b/src/target/fake_trx/data_dump.py index b9047365..56e314c4 100644 --- a/src/target/fake_trx/data_dump.py +++ b/src/target/fake_trx/data_dump.py @@ -30,7 +30,7 @@ class DATADump: # Constants TAG_L12TRX = '\x01' TAG_TRX2L1 = '\x02' - HDR_LENGTH = 2 + HDR_LENGTH = 3 # Generates raw bytes from a DATA message # Return value: raw message bytes @@ -46,15 +46,18 @@ class DATADump: # Generate a message payload msg_raw = msg.gen_msg() - # Calculate the length + # Calculate and pack the message length msg_len = len(msg_raw) + # Pack to unsigned short (2 bytes, BE) + msg_len = struct.pack(">H", msg_len) + # Concatenate a message with header - return bytearray([tag, msg_len]) + msg_raw + return bytearray(tag + msg_len) + msg_raw def parse_hdr(self, hdr): # Extract the header info - msg_len = struct.unpack("<B", hdr[1])[0] + msg_len = struct.unpack(">H", hdr[1:3])[0] tag = hdr[0] # Check if tag is known |