1#/usr/bin/env python3.4
2#
3# Copyright (C) 2009 Google Inc.
4#
5# Licensed under the Apache License, Version 2.0 (the "License"); you may not
6# use this file except in compliance with the License. You may obtain a copy of
7# the License at
8#
9# http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
13# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
14# License for the specific language governing permissions and limitations under
15# the License.
16"""
17JSON RPC interface to android scripting engine.
18"""
19
20from builtins import str
21
22import json
23import os
24import socket
25import threading
26import time
27
28HOST = os.environ.get('AP_HOST', None)
29PORT = os.environ.get('AP_PORT', 9999)
30
31
32class SL4AException(Exception):
33    pass
34
35
36class SL4AAPIError(SL4AException):
37    """Raised when remote API reports an error."""
38
39
40class SL4AProtocolError(SL4AException):
41    """Raised when there is some error in exchanging data with server on device."""
42    NO_RESPONSE_FROM_HANDSHAKE = "No response from handshake."
43    NO_RESPONSE_FROM_SERVER = "No response from server."
44    MISMATCHED_API_ID = "Mismatched API id."
45
46
47def IDCounter():
48    i = 0
49    while True:
50        yield i
51        i += 1
52
53
54class Android(object):
55    COUNTER = IDCounter()
56
57    _SOCKET_CONNECT_TIMEOUT = 60
58
59    def __init__(self,
60                 cmd='initiate',
61                 uid=-1,
62                 port=PORT,
63                 addr=HOST,
64                 timeout=None):
65        self.lock = threading.RLock()
66        self.client = None  # prevent close errors on connect failure
67        self.uid = None
68        timeout_time = time.time() + self._SOCKET_CONNECT_TIMEOUT
69        while True:
70            try:
71                self.conn = socket.create_connection(
72                    (addr, port), max(1, timeout_time - time.time()))
73                self.conn.settimeout(timeout)
74                break
75            except (TimeoutError, socket.timeout):
76                print("Failed to create socket connection!")
77                raise
78            except (socket.error, IOError):
79                # TODO: optimize to only forgive some errors here
80                # error values are OS-specific so this will require
81                # additional tuning to fail faster
82                if time.time() + 1 >= timeout_time:
83                    print("Failed to create socket connection!")
84                    raise
85                time.sleep(1)
86
87        self.client = self.conn.makefile(mode="brw")
88
89        resp = self._cmd(cmd, uid)
90        if not resp:
91            raise SL4AProtocolError(
92                SL4AProtocolError.NO_RESPONSE_FROM_HANDSHAKE)
93        result = json.loads(str(resp, encoding="utf8"))
94        if result['status']:
95            self.uid = result['uid']
96        else:
97            self.uid = -1
98
99    def close(self):
100        if self.conn is not None:
101            self.conn.close()
102            self.conn = None
103
104    def _cmd(self, command, uid=None):
105        if not uid:
106            uid = self.uid
107        self.client.write(json.dumps({'cmd': command,
108                                      'uid': uid}).encode("utf8") + b'\n')
109        self.client.flush()
110        return self.client.readline()
111
112    def _rpc(self, method, *args):
113        self.lock.acquire()
114        apiid = next(Android.COUNTER)
115        self.lock.release()
116        data = {'id': apiid, 'method': method, 'params': args}
117        request = json.dumps(data)
118        self.client.write(request.encode("utf8") + b'\n')
119        self.client.flush()
120        response = self.client.readline()
121        if not response:
122            raise SL4AProtocolError(SL4AProtocolError.NO_RESPONSE_FROM_SERVER)
123        result = json.loads(str(response, encoding="utf8"))
124        if result['error']:
125            raise SL4AAPIError(result['error'])
126        if result['id'] != apiid:
127            raise SL4AProtocolError(SL4AProtocolError.MISMATCHED_API_ID)
128        return result['result']
129
130    def __getattr__(self, name):
131        def rpc_call(*args):
132            return self._rpc(name, *args)
133
134        return rpc_call
135