xref: /aosp_15_r20/external/autotest/frontend/afe/json_rpc/serviceHandler.py (revision 9c5db1993ded3edbeafc8092d69fe5de2ee02df7) 
1"""
2  Copyright (c) 2007 Jan-Klaas Kollhof
3
4  This file is part of jsonrpc.
5
6  jsonrpc is free software; you can redistribute it and/or modify
7  it under the terms of the GNU Lesser General Public License as published by
8  the Free Software Foundation; either version 2.1 of the License, or
9  (at your option) any later version.
10
11  This software is distributed in the hope that it will be useful,
12  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  GNU Lesser General Public License for more details.
15
16  You should have received a copy of the GNU Lesser General Public License
17  along with this software; if not, write to the Free Software
18  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19"""
20
21from __future__ import absolute_import
22from __future__ import division
23from __future__ import print_function
24
25import socket
26import traceback
27
28from json import decoder
29
30import six
31
32try:
33    from django.core import exceptions as django_exceptions
34    # Django JSON encoder uses the standard json encoder but can handle DateTime
35    from django.core.serializers import json as django_encoder
36    json_encoder = django_encoder.DjangoJSONEncoder()
37except django_exceptions.ImproperlyConfigured:
38    from json import encoder
39    json_encoder = encoder.JSONEncoder()
40
41
42json_decoder = decoder.JSONDecoder()
43
44
45def customConvertJson(value):
46    """\
47    Recursively process JSON values and do type conversions.
48    -change floats to ints
49    -change unicodes to strs
50    """
51    if isinstance(value, float):
52        return int(value)
53    elif isinstance(value, six.text_type):
54        return str(value)
55    elif isinstance(value, list):
56        return [customConvertJson(item) for item in value]
57    elif isinstance(value, dict):
58        new_dict = {}
59        for key, val in six.iteritems(value):
60            new_key = customConvertJson(key)
61            new_val = customConvertJson(val)
62            new_dict[new_key] = new_val
63        return new_dict
64    else:
65        return value
66
67
68def ServiceMethod(fn):
69    fn.IsServiceMethod = True
70    return fn
71
72class ServiceException(Exception):
73    pass
74
75class ServiceRequestNotTranslatable(ServiceException):
76    pass
77
78class BadServiceRequest(ServiceException):
79    pass
80
81class ServiceMethodNotFound(ServiceException):
82    pass
83
84
85class ServiceHandler(object):
86
87    def __init__(self, service):
88        self.service=service
89
90
91    @classmethod
92    def blank_result_dict(cls):
93        return {'id': None, 'result': None, 'err': None, 'err_traceback': None}
94
95    def dispatchRequest(self, request):
96        """
97        Invoke a json RPC call from a decoded json request.
98        @param request: a decoded json_request
99        @returns a dictionary with keys id, result, err and err_traceback
100        """
101        results = self.blank_result_dict()
102
103        try:
104            results['id'] = self._getRequestId(request)
105            methName = request['method']
106            args = request['params']
107        except KeyError:
108            raise BadServiceRequest(request)
109
110        metadata = request.copy()
111        metadata['_type'] = 'rpc'
112        metadata['rpc_server'] = socket.gethostname()
113        try:
114            meth = self.findServiceEndpoint(methName)
115            results['result'] = self.invokeServiceEndpoint(meth, args)
116        except Exception as err:
117            results['err_traceback'] = traceback.format_exc()
118            results['err'] = err
119
120        return results
121
122
123    def _getRequestId(self, request):
124        try:
125            return request['id']
126        except KeyError:
127            raise BadServiceRequest(request)
128
129
130    def handleRequest(self, jsonRequest):
131        request = self.translateRequest(jsonRequest)
132        results = self.dispatchRequest(request)
133        return self.translateResult(results)
134
135
136    @staticmethod
137    def translateRequest(data):
138        try:
139            req = json_decoder.decode(data)
140        except:
141            raise ServiceRequestNotTranslatable(data)
142        req = customConvertJson(req)
143        return req
144
145    def findServiceEndpoint(self, name):
146        try:
147            meth = getattr(self.service, name)
148            return meth
149        except AttributeError:
150            raise ServiceMethodNotFound(name)
151
152    def invokeServiceEndpoint(self, meth, args):
153        return meth(*args)
154
155    @staticmethod
156    def translateResult(result_dict):
157        """
158        @param result_dict: a dictionary containing the result, error, traceback
159                            and id.
160        @returns translated json result
161        """
162        if result_dict['err'] is not None:
163            error_name = result_dict['err'].__class__.__name__
164            result_dict['err'] = {'name': error_name,
165                                  'message': str(result_dict['err']),
166                                  'traceback': result_dict['err_traceback']}
167            result_dict['result'] = None
168
169        try:
170            json_dict = {'result': result_dict['result'],
171                         'id': result_dict['id'],
172                         'error': result_dict['err'] }
173            data = json_encoder.encode(json_dict)
174        except TypeError as e:
175            err_traceback = traceback.format_exc()
176            print(err_traceback)
177            err = {"name" : "JSONEncodeException",
178                   "message" : "Result Object Not Serializable",
179                   "traceback" : err_traceback}
180            data = json_encoder.encode({"result":None, "id":result_dict['id'],
181                                        "error":err})
182
183        return data
184