mirror of
https://github.com/trezor/trezor-firmware.git
synced 2024-12-12 09:28:10 +00:00
244 lines
8.1 KiB
Python
244 lines
8.1 KiB
Python
from micropython import const
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import ustruct
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from trezor import loop
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from trezor import utils
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from trezor.crypto import random
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# TREZOR wire protocol #2:
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#
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# # Initial message report
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# uint8_t marker; // REP_MARKER_INIT
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# uint32_t session_id; // Big-endian
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# uint32_t message_type; // Big-endian
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# uint32_t message_size; // Big-endian
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# uint8_t data[];
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#
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# # Continuation message report
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# uint8_t marker; // REP_MARKER_CONT
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# uint32_t session_id; // Big-endian
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# uint32_t sequence; // Big-endian, 0 for 1st continuation report
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# uint8_t data[];
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_REP_LEN = const(64)
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_REP_MARKER_INIT = const(0x01)
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_REP_MARKER_CONT = const(0x02)
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_REP_MARKER_OPEN = const(0x03)
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_REP_MARKER_CLOSE = const(0x04)
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_REP = '>BL' # marker, session_id
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_REP_INIT = '>BLLL' # marker, session_id, message_type, message_size
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_REP_CONT = '>BLL' # marker, session_id, sequence
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_REP_INIT_DATA = const(13) # offset of data in init report
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_REP_CONT_DATA = const(9) # offset of data in cont report
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class Reader:
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'''
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Decoder for v2 codec over the HID layer. Provides readable async-file-like
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interface.
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'''
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def __init__(self, iface, sid):
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self.iface = iface
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self.sid = sid
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self.type = None
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self.size = None
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self.data = None
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self.ofs = 0
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self.seq = 0
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def __repr__(self):
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return '<Reader: sid=%x type=%d size=%dB>' % (self.sid, self.type,
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self.size)
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async def aopen(self):
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'''
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Begin the message transmission by waiting for initial V2 message report
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on this session. `self.type` and `self.size` are initialized and
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available after `aopen()` returns.
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'''
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read = loop.select(self.iface.iface_num() | loop.READ)
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while True:
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# wait for initial report
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report = await read
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marker, sid, mtype, msize = ustruct.unpack(_REP_INIT, report)
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if sid == self.sid and marker == _REP_MARKER_INIT:
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break
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# load received message header
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self.type = mtype
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self.size = msize
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self.data = report[_REP_INIT_DATA:_REP_INIT_DATA + msize]
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self.ofs = 0
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self.seq = 0
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async def areadinto(self, buf):
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'''
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Read exactly `len(buf)` bytes into `buf`, waiting for additional
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reports, if needed. Raises `EOFError` if end-of-message is encountered
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before the full read can be completed.
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'''
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if self.size < len(buf):
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raise EOFError
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read = loop.select(self.iface.iface_num() | loop.READ)
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nread = 0
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while nread < len(buf):
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if self.ofs == len(self.data):
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# we are at the end of received data
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# wait for continuation report
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while True:
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report = await read
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marker, sid, seq = ustruct.unpack(_REP_CONT, report)
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if sid == self.sid and marker == _REP_MARKER_CONT:
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if seq != self.seq:
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raise ValueError
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break
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self.data = report[_REP_CONT_DATA:_REP_CONT_DATA + self.size]
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self.seq += 1
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self.ofs = 0
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# copy as much as possible to target buffer
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nbytes = utils.memcpy(buf, nread, self.data, self.ofs, len(buf))
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nread += nbytes
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self.ofs += nbytes
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self.size -= nbytes
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return nread
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class Writer:
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'''
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Encoder for v2 codec over the HID layer. Provides writable async-file-like
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interface.
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'''
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def __init__(self, iface, sid):
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self.iface = iface
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self.sid = sid
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self.type = None
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self.size = None
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self.data = bytearray(_REP_LEN)
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self.ofs = 0
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self.seq = 0
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def __repr__(self):
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return '<WriterV2: type=%d size=%dB>' % (self.type, self.size)
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def setheader(self, mtype, msize):
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'''
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Reset the writer state and load the message header with passed type and
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total message size.
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'''
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self.type = mtype
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self.size = msize
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ustruct.pack_into(_REP_INIT, self.data, 0, _REP_MARKER_INIT, self.sid,
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mtype, msize)
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self.ofs = _REP_INIT_DATA
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self.seq = 0
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async def awrite(self, buf):
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'''
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Encode and write every byte from `buf`. Does not need to be called in
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case message has zero length. Raises `EOFError` if the length of `buf`
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exceeds the remaining message length.
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'''
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if self.size < len(buf):
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raise EOFError
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write = loop.select(self.iface.iface_num() | loop.WRITE)
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nwritten = 0
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while nwritten < len(buf):
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# copy as much as possible to report buffer
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nbytes = utils.memcpy(self.data, self.ofs, buf, nwritten, len(buf))
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nwritten += nbytes
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self.ofs += nbytes
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self.size -= nbytes
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if self.ofs == _REP_LEN:
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# we are at the end of the report, flush it, and prepare header
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await write
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self.iface.write(self.data)
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ustruct.pack_into(_REP_CONT, self.data, 0, _REP_MARKER_CONT,
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self.sid, self.seq)
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self.ofs = _REP_CONT_DATA
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self.seq += 1
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return nwritten
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async def aclose(self):
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'''Flush and close the message transmission.'''
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if self.ofs != _REP_CONT_DATA:
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# we didn't write anything or last write() wasn't report-aligned,
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# pad the final report and flush it
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while self.ofs < _REP_LEN:
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self.data[self.ofs] = 0x00
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self.ofs += 1
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await loop.select(self.iface.iface_num() | loop.WRITE)
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self.iface.write(self.data)
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class SesssionSupervisor:
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'''Handles session open/close requests on v2 protocol layer.'''
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def __init__(self, iface, handler):
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self.iface = iface
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self.handler = handler
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self.handling_tasks = {}
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self.session_report = bytearray(_REP_LEN)
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async def listen(self):
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'''
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Listen for open/close requests on configured interface. After open
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request, session is started and a new task is scheduled to handle it.
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After close request, the handling task is closed and session terminated.
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Both requests receive responses confirming the operation.
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'''
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read = loop.select(self.iface.iface_num() | loop.READ)
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write = loop.select(self.iface.iface_num() | loop.WRITE)
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while True:
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report = await read
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repmarker, repsid = ustruct.unpack(_REP, report)
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# because tasks paused on I/O have a priority over time-scheduled
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# tasks, we need to `yield` explicitly before sending a response to
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# open/close request. Otherwise the handler would have no chance to
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# run and schedule communication.
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if repmarker == _REP_MARKER_OPEN:
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newsid = self.newsid()
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self.open(newsid)
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yield
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await write
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self.writeopen(newsid)
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elif repmarker == _REP_MARKER_CLOSE:
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self.close(repsid)
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yield
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await write
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self.writeclose(repsid)
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def open(self, sid):
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if sid not in self.handling_tasks:
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task = self.handling_tasks[sid] = self.handler(self.iface, sid)
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loop.schedule_task(task)
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def close(self, sid):
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if sid in self.handling_tasks:
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task = self.handling_tasks.pop(sid)
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task.close()
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def newsid(self):
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while True:
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sid = random.uniform(0xffffffff) + 1
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if sid not in self.handling_tasks:
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return sid
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def writeopen(self, sid):
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ustruct.pack_into(_REP, self.session_report, 0, _REP_MARKER_OPEN, sid)
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self.iface.write(self.session_report)
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def writeclose(self, sid):
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ustruct.pack_into(_REP, self.session_report, 0, _REP_MARKER_CLOSE, sid)
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self.iface.write(self.session_report)
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