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62 lines
1.9 KiB
Python
62 lines
1.9 KiB
Python
import struct
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from bitkey_proto import bitkey_pb2 as proto
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from bitkey_proto import mapping
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class Transport(object):
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def __init__(self, device, *args, **kwargs):
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self.device = device
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self._open()
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def _open(self):
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raise NotImplemented
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def _close(self):
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raise NotImplemented
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def _write(self, msg):
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raise NotImplemented
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def _read(self):
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raise NotImplemented
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def close(self):
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self._close()
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def write(self, msg):
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ser = msg.SerializeToString()
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header = struct.pack(">HL", mapping.get_type(msg), len(ser))
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self._write("##%s%s" % (header, ser))
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def read(self):
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(msg_type, data) = self._read()
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inst = mapping.get_class(msg_type)()
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inst.ParseFromString(data)
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return inst
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def _read_headers(self, read_f):
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# Try to read headers until some sane value are detected
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is_ok = False
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while not is_ok:
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# Align cursor to the beginning of the header ("##")
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c = read_f.read(1)
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while c != '#':
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if c == '':
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# timeout
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raise Exception("Timed out while waiting for the magic character")
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print "Warning: Aligning to magic characters"
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c = read_f.read(1)
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if read_f.read(1) != "#":
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# Second character must be # to be valid header
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raise Exception("Second magic character is broken")
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# Now we're most likely on the beginning of the header
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try:
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headerlen = struct.calcsize(">HL")
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(msg_type, datalen) = struct.unpack(">HL", read_f.read(headerlen))
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break
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except:
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raise Exception("Cannot parse header length")
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return (msg_type, datalen) |