1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
# IVLE - Informatics Virtual Learning Environment
# Copyright (C) 2007-2009 The University of Melbourne
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# Author: Matt Giuca, Will Grant
import cgi
import inspect
import cjson
from ivle.webapp.base.views import BaseView
from ivle.webapp.errors import BadRequest, MethodNotAllowed, Unauthorized
class RESTView(BaseView):
"""
A view which provides a RESTful interface. The content type is
unspecified (see JSONRESTView for a specific content type).
"""
content_type = "application/octet-stream"
def __init__(self, req, *args, **kwargs):
for key in kwargs:
setattr(self, key, kwargs[key])
def render(self, req):
raise NotImplementedError()
class JSONRESTView(RESTView):
"""
A special case of RESTView which deals entirely in JSON.
"""
content_type = "application/json"
_allowed_methods = property(
lambda self: [m for m in ('GET', 'PUT', 'PATCH')
if hasattr(self, m)] + ['POST'])
def authorize(self, req):
return True # Real authz performed in render().
def authorize_method(self, req, op):
if not hasattr(op, '_rest_api_permission'):
raise Unauthorized()
if op._rest_api_permission not in self.get_permissions(req.user):
raise Unauthorized()
def render(self, req):
if req.method not in self._allowed_methods:
raise MethodNotAllowed(allowed=self._allowed_methods)
if req.method == 'GET':
self.authorize_method(req, self.GET)
outjson = self.GET(req)
# Since PATCH isn't yet an official HTTP method, we allow users to
# turn a PUT into a PATCH by supplying a special header.
elif req.method == 'PATCH' or (req.method == 'PUT' and
'X-IVLE-Patch-Semantics' in req.headers_in and
req.headers_in['X-IVLE-Patch-Semantics'].lower() == 'yes'):
self.authorize_method(req, self.PATCH)
try:
input = cjson.decode(req.read())
except cjson.DecodeError:
raise BadRequest('Invalid JSON data')
outjson = self.PATCH(req, input)
elif req.method == 'PUT':
self.authorize_method(req, self.PUT)
try:
input = cjson.decode(req.read())
except cjson.DecodeError:
raise BadRequest('Invalid JSON data')
outjson = self.PUT(req, input)
# POST implies named operation.
elif req.method == 'POST':
# TODO: Check Content-Type and implement multipart/form-data.
opargs = dict(cgi.parse_qsl(req.read()))
try:
opname = opargs['ivle.op']
del opargs['ivle.op']
except KeyError:
raise BadRequest('No named operation specified.')
try:
op = getattr(self, opname)
except AttributeError:
raise BadRequest('Invalid named operation.')
if not hasattr(op, '_rest_api_callable') or \
not op._rest_api_callable:
raise BadRequest('Invalid named operation.')
self.authorize_method(req, op)
# Find any missing arguments, except for the first two (self, req)
(args, vaargs, varkw, defaults) = inspect.getargspec(op)
args = args[2:]
# To find missing arguments, we eliminate the provided arguments
# from the set of remaining function signature arguments. If the
# remaining signature arguments are in the args[-len(defaults):],
# we are OK.
unspec = set(args) - set(opargs.keys())
if unspec and not defaults:
raise BadRequest('Missing arguments: ' + ', '.join(unspec))
unspec = [k for k in unspec if k not in args[-len(defaults):]]
if unspec:
raise BadRequest('Missing arguments: ' + ', '.join(unspec))
# We have extra arguments if the are no match args in the function
# signature, AND there is no **.
extra = set(opargs.keys()) - set(args)
if extra and not varkw:
raise BadRequest('Extra arguments: ' + ', '.join(extra))
outjson = op(req, **opargs)
req.content_type = self.content_type
if outjson is not None:
req.write(cjson.encode(outjson))
req.write("\n")
class named_operation(object):
'''Declare a function to be accessible to HTTP users via the REST API.
'''
def __init__(self, permission):
self.permission = permission
def __call__(self, func):
func._rest_api_callable = True
func._rest_api_permission = self.permission
return func
class require_permission(object):
'''Declare the permission required for use of a method via the REST API.
'''
def __init__(self, permission):
self.permission = permission
def __call__(self, func):
func._rest_api_permission = self.permission
return func
|