def read(self, fmt):
st = struct.Struct(fmt)
if self.offset + st.size > self.length:
raise lowpan.ProtocolError("Buffer too short")
result = st.unpack_from(self.buf, self.start+self.offset)
self.offset += st.size
return result
def slice(self, length, rewind=0):
if self.offset + length - rewind > self.length:
raise lowpan.ProtocolError("Buffer too short")
reader = BufReader(self.buf, self.start + self.offset - rewind, length)
reader.skip(rewind)
self.offset += length - rewind
return reader
def skip_align(self):
new_offset = (self.offset + 7) / 8 * 8
if new_offset > self.length:
raise lowpan.ProtocolError("Buffer too short")
self.offset = new_offset
def skip(self, length):
if self.offset + length > self.length:
raise lowpan.ProtocolError("Buffer too short")
self.offset += length
def parse_pkt(buf):
if len(buf) < 64:
raise lowpan.ProtocolError("too short to be an l2 ethernet packet")
return PACKET.unpack(lowpan.util.BufReader(buf))
def parse_802_15_4_header(buf):
if len(buf) < 8:
raise lowpan.ProtocolError("too short to be an 802.15.4 packet")
data = IEEE_802_15_4_DATA.unpack(lowpan.util.BufReader(buf))
return data.mhr_len, (len(buf) - 2), data.pattern
def parse_header(buf):
if len(buf) < 8:
raise lowpan.ProtocolError("too short to be an 802.15.4 packet")
l_sniffer = NXP_802_15_4_Sniffer.unpack(lowpan.util.BufReader(buf))
return l_sniffer.hdr_len, l_sniffer.len, l_sniffer.subtype, l_sniffer