Validate resolve request response

[ghost]

Raiden crashes when xud's hash resolver request returns an unexpected response.

2019-08-09 11:38:30.103106 [info     ] 127.0.0.1 - - [2019-08-09 11:38:30] "GET /api/v1/channels/0x6f59245d93f6fac22b60525a9bf2ae8301c2e11a HTTP/1.1" 200 466 0.003887 [raiden.api.rest.pywsgi]
Traceback (most recent call last):
  File "/home/ar/raiden/venv/lib/python3.7/encodings/hex_codec.py", line 19, in hex_decode
    return (binascii.a2b_hex(input), len(input))
binascii.Error: Non-hexadecimal digit found

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 716, in gevent._greenlet.Greenlet.run
  File "/home/ar/raiden/raiden/raiden_service.py", line 720, in _handle_event
    raiden=self, chain_state=chain_state, event=raiden_event
  File "/home/ar/raiden/raiden/raiden_event_handler.py", line 106, in on_raiden_event
    self.handle_send_secretrequest(raiden, event)
  File "/home/ar/raiden/raiden/raiden_event_handler.py", line 174, in handle_send_secretrequest
    if reveal_secret_with_resolver(raiden, secret_request_event):
  File "/home/ar/raiden/raiden/network/resolver/client.py", line 46, in reveal_secret_with_resolver
    secret = to_bytes(hexstr=hexsecret)
  File "/home/ar/raiden/venv/lib/python3.7/site-packages/eth_utils/decorators.py", line 75, in wrapper
    return to_wrap(*args, **kwargs)
  File "/home/ar/raiden/venv/lib/python3.7/site-packages/eth_utils/conversions.py", line 88, in to_bytes
    return decode_hex(hexstr)
  File "/home/ar/raiden/venv/lib/python3.7/site-packages/eth_utils/hexadecimal.py", line 17, in decode_hex
    return codecs.decode(remove_0x_prefix(value), "hex")  # type: ignore
binascii.Error: decoding with 'hex' codec failed (Error: Non-hexadecimal digit found)
2019-08-09T11:38:58Z <Greenlet "Greenlet-6" at 0x7f969922e488: <bound method RaidenService._handle_event of <RaidenService node:efd2860f>>(<ChainState block_number:2568 block_hash:c71aa8da , <SendSecretRequest msgid:464343788158544418 paymen)> failed with Error

2019-08-09 11:38:58.805632 [error    ] Runnable subtask died!         [raiden.utils.runnable] exc=Error("decoding with 'hex' codec failed (Error: Non-hexadecimal digit found)") running=True subtask=<Greenlet "Greenlet-6" at 0x7f969922e488: <bound method RaidenService._handle_event of <RaidenService node:efd2860f>>(<ChainState block_number:2568 block_hash:c71aa8da , <SendSecretRequest msgid:464343788158544418 paymen)> this=<RaidenService node:efd2860f>
Traceback (most recent call last):
  File "/home/ar/raiden/venv/lib/python3.7/encodings/hex_codec.py", line 19, in hex_decode
    return (binascii.a2b_hex(input), len(input))
binascii.Error: Non-hexadecimal digit found

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "src/gevent/greenlet.py", line 716, in gevent._greenlet.Greenlet.run
  File "/home/ar/raiden/raiden/raiden_service.py", line 533, in _run
    self.stop_event.wait()
  File "src/gevent/event.py", line 240, in gevent._event.Event.wait
  File "src/gevent/event.py", line 140, in gevent._event._AbstractLinkable._wait
  File "src/gevent/event.py", line 117, in gevent._event._AbstractLinkable._wait_core
  File "src/gevent/event.py", line 119, in gevent._event._AbstractLinkable._wait_core
  File "src/gevent/_greenlet_primitives.py", line 59, in gevent.__greenlet_primitives.SwitchOutGreenletWithLoop.switch
  File "src/gevent/_greenlet_primitives.py", line 59, in gevent.__greenlet_primitives.SwitchOutGreenletWithLoop.switch
  File "src/gevent/_greenlet_primitives.py", line 63, in gevent.__greenlet_primitives.SwitchOutGreenletWithLoop.switch
  File "src/gevent/__greenlet_primitives.pxd", line 35, in gevent.__greenlet_primitives._greenlet_switch
binascii.Error: decoding with 'hex' codec failed (Error: Non-hexadecimal digit found)
2019-08-09T11:39:00Z <Greenlet "RaidenService._run node:efd2860f" at 0x7f9699d1e158: <bound method RaidenService._run of <RaidenService node:efd2860f>>> failed with Error

FATAL: An unexpected exception occured. A traceback has been written to /tmp/raiden-exception-2019-08-09T11-39apz0ekgs.txt
decoding with 'hex' codec failed (Error: Non-hexadecimal digit found)

[kilrau]

ExchangeUnion/xud#1172 (comment)

[kilrau]

Closed by ExchangeUnion/xud#1172 @erkarl ?

[ghost]

Not closed. This issue is about validating the request raiden receives from xud. The above mentioned issue does validations from the xud side.

Agree with the priority - not a huge deal right now.