bridge: refactor after merging old changes

trezorlib/transport/bridge.py

@@ -14,7 +14,6 @@
 # You should have received a copy of the License along with this library.
 # If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.
 
-import binascii
 import logging
 import struct
 from io import BytesIO
@@ -28,10 +27,21 @@ from .. import mapping, protobuf
 LOG = logging.getLogger(__name__)
 
 TREZORD_HOST = "http://127.0.0.1:21325"
+TREZORD_ORIGIN_HEADER = {"Origin": "https://python.trezor.io"}
+
+CONNECTION = requests.Session()
+CONNECTION.headers.update(TREZORD_ORIGIN_HEADER)
 
 
-def get_error(resp: requests.Response) -> str:
-    return " (error=%d str=%s)" % (resp.status_code, resp.json()["error"])
+def call_bridge(uri: str, data=None) -> requests.Response:
+    url = TREZORD_HOST + "/" + uri
+    r = CONNECTION.post(url, data=data)
+    if r.status_code != 200:
+        error_str = "trezord: {} failed with code {}: {}".format(
+            uri, r.status_code, r.json()["error"]
+        )
+        raise TransportException(error_str)
+    return r
 
 
 class BridgeTransport(Transport):
@@ -40,13 +50,12 @@ class BridgeTransport(Transport):
     """
 
     PATH_PREFIX = "bridge"
-    HEADERS = {"Origin": "https://python.trezor.io"}
 
     def __init__(self, device: Dict[str, Any]) -> None:
         self.device = device
-        self.conn = requests.Session()
         self.session = None  # type: Optional[str]
-        self.response = None  # type: Optional[str]
+        self.request = None  # type: Optional[str]
+        self.debug = False
 
     def get_path(self) -> str:
         return "%s:%s" % (self.PATH_PREFIX, self.device["path"])
@@ -54,39 +63,32 @@ class BridgeTransport(Transport):
     @classmethod
     def enumerate(cls) -> Iterable["BridgeTransport"]:
         try:
-            r = requests.post(TREZORD_HOST + "/enumerate", headers=cls.HEADERS)
-            if r.status_code != 200:
-                raise TransportException(
-                    "trezord: Could not enumerate devices" + get_error(r)
-                )
-            return [BridgeTransport(dev) for dev in r.json()]
+            return [BridgeTransport(dev) for dev in call_bridge("enumerate").json()]
         except Exception:
             return []
 
+    def _call(self, action: str, data: str = None) -> requests.Response:
+        session = self.session or "null"
+        uri = action + "/" + str(session)
+        return call_bridge(uri, data=data)
+
     def begin_session(self) -> None:
-        r = self.conn.post(
-            TREZORD_HOST + "/acquire/%s/null" % self.device["path"],
-            headers=self.HEADERS,
-        )
-        if r.status_code != 200:
-            raise TransportException(
-                "trezord: Could not acquire session" + get_error(r)
-            )
-        self.session = r.json()["session"]
+        LOG.debug("acquiring session from {}".format(self.session))
+        data = self._call("acquire/" + self.device["path"])
+        self.session = data.json()["session"]
+        LOG.debug("acquired session {}".format(self.session))
 
     def end_session(self) -> None:
+        LOG.debug("releasing session {}".format(self.session))
         if not self.session:
             return
-        r = self.conn.post(
-            TREZORD_HOST + "/release/%s" % self.session, headers=self.HEADERS
-        )
-        if r.status_code != 200:
-            raise TransportException(
-                "trezord: Could not release session" + get_error(r)
-            )
+        self._call("release")
         self.session = None
 
     def write(self, msg: protobuf.MessageType) -> None:
+        if self.request is not None:
+            raise TransportException("Cannot enqueue two requests")
+
         LOG.debug(
             "sending message: {}".format(msg.__class__.__name__),
             extra={"protobuf": msg},
@@ -95,28 +97,26 @@ class BridgeTransport(Transport):
         protobuf.dump_message(buffer, msg)
         ser = buffer.getvalue()
         header = struct.pack(">HL", mapping.get_type(msg), len(ser))
-        data = binascii.hexlify(header + ser).decode()
-        r = self.conn.post(  # type: ignore  # typeshed bug
-            TREZORD_HOST + "/call/%s" % self.session, data=data, headers=self.HEADERS
-        )
-        if r.status_code != 200:
-            raise TransportException("trezord: Could not write message" + get_error(r))
-        self.response = r.text
+
+        self.request = (header + ser).hex()
 
     def read(self) -> protobuf.MessageType:
-        if self.response is None:
-            raise TransportException("No response stored")
-        data = binascii.unhexlify(self.response)
+        if self.request is None:
+            raise TransportException("No request stored")
+
+        try:
+            data = bytes.fromhex(self._call("call", data=self.request).text)
             headerlen = struct.calcsize(">HL")
-        (msg_type, datalen) = struct.unpack(">HL", data[:headerlen])
+            msg_type, datalen = struct.unpack(">HL", data[:headerlen])
             buffer = BytesIO(data[headerlen : headerlen + datalen])
             msg = protobuf.load_message(buffer, mapping.get_class(msg_type))
             LOG.debug(
                 "received message: {}".format(msg.__class__.__name__),
                 extra={"protobuf": msg},
             )
-        self.response = None
             return msg
+        finally:
+            self.request = None
 
 
 TRANSPORT = BridgeTransport