summaryrefslogtreecommitdiffstats
path: root/tests/api/fuzzer.py
blob: ee12a028afd024baddaea65dc8bbba9d77411c24 (plain)
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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
import argparse
import json
import logging
import posixpath
import random
import re
import requests
import string
import sys
import urllib.parse

#######################################################################################################################
# Utilities


def some(s):
    return random.choice(sorted(s))


def not_some(s):
    test_set = random.choice([string.ascii_uppercase + string.ascii_lowercase,
                              string.digits,
                              string.digits + ".E-",
                              '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJK'
                              'LMNOPQRSTUVWXYZ!"#$%\'()*+,-./:;<=>?@[\\]^_`{|}~ '])
    test_len = random.choice([1, 2, 3, 37, 61, 121])
    while True:
        x = ''.join([random.choice(test_set) for _ in range(test_len)])
        if x not in s:
            return x


def build_url(host_maybe_scheme, base_path):
    try:
        if '//' not in host_maybe_scheme:
            host_maybe_scheme = '//' + host_maybe_scheme
        url_tuple = urllib.parse.urlparse(host_maybe_scheme)
        if base_path[0] == '/':
            base_path = base_path[1:]
        return url_tuple.netloc, posixpath.join(url_tuple.path, base_path)
    except Exception as e:
        L.error(f"Critical failure decoding arguments -> {e}")
        sys.exit(-1)


#######################################################################################################################
# Data-model and processing


class Param(object):
    def __init__(self, name, location, kind):
        self.location = location
        self.kind = kind
        self.name = name
        self.values = set()

    def dump(self):
        print(f"{self.name} in {self.location} is {self.kind} : {{{self.values}}}")


def does_response_fit_schema(schema_path, schema, resp):
    '''The schema_path argument tells us where we are (globally) in the schema. The schema argument is the
       sub-tree within the schema json that we are validating against. The resp is the json subtree from the
       target host's response.

       The basic idea is this: swagger defines a model of valid json trees. In this sense it is a formal
       language and we can validate a given server response by checking if the language accepts a particular
       server response. This is basically a parser, but instead of strings we are operating on languages
       of trees.

       This could probably be extended to arbitrary swagger definitions - but the amount of work increases
       rapidly as we attempt to cover the full semantics of languages of trees defined in swagger. Instead
       we have some special cases that describe the parts of the semantics that we've used to describe the
       netdata API.

       If we hit an error (in the schema) that prevents further checks then we return early, otherwise we
       try to collect as many errors as possible.
    '''
    success = True
    if "type" not in schema:
        L.error(f"Cannot progress past {schema_path} -> no type specified in dictionary")
        print(json.dumps(schema, indent=2))
        return False
    if schema["type"] == "object":
        if isinstance(resp, dict) and "properties" in schema and isinstance(schema["properties"], dict):
            L.debug(f"Validate properties against dictionary at {schema_path}")
            for k, v in schema["properties"].items():
                L.debug(f"Validate {k} received with {v}")
                if v.get("required", False) and k not in resp:
                    L.error(f"Missing {k} in response at {schema_path}")
                    print(json.dumps(resp, indent=2))
                    return False
                if k in resp:
                    if not does_response_fit_schema(posixpath.join(schema_path, k), v, resp[k]):
                        success = False
        elif isinstance(resp, dict) and "additionalProperties" in schema \
                and isinstance(schema["additionalProperties"], dict):
            kv_schema = schema["additionalProperties"]
            L.debug(f"Validate additionalProperties against every value in dictionary at {schema_path}")
            if "type" in kv_schema and kv_schema["type"] == "object":
                for k, v in resp.items():
                    if not does_response_fit_schema(posixpath.join(schema_path, k), kv_schema, v):
                        success = False
            else:
                L.error("Don't understand what the additionalProperties means (it has no type?)")
                return False
        else:
            L.error(f"Can't understand schema at {schema_path}")
            print(json.dumps(schema, indent=2))
            return False
    elif schema["type"] == "string":
        if isinstance(resp, str):
            L.debug(f"{repr(resp)} matches {repr(schema)} at {schema_path}")
            return True
        L.error(f"{repr(resp)} does not match schema {repr(schema)} at {schema_path}")
        return False
    elif schema["type"] == "boolean":
        if isinstance(resp, bool):
            L.debug(f"{repr(resp)} matches {repr(schema)} at {schema_path}")
            return True
        L.error(f"{repr(resp)} does not match schema {repr(schema)} at {schema_path}")
        return False
    elif schema["type"] == "number":
        if 'nullable' in schema and resp is None:
            L.debug(f"{repr(resp)} matches {repr(schema)} at {schema_path} (because nullable)")
            return True
        if isinstance(resp, int) or isinstance(resp, float):
            L.debug(f"{repr(resp)} matches {repr(schema)} at {schema_path}")
            return True
        L.error(f"{repr(resp)} does not match schema {repr(schema)} at {schema_path}")
        return False
    elif schema["type"] == "integer":
        if 'nullable' in schema and resp is None:
            L.debug(f"{repr(resp)} matches {repr(schema)} at {schema_path} (because nullable)")
            return True
        if isinstance(resp, int):
            L.debug(f"{repr(resp)} matches {repr(schema)} at {schema_path}")
            return True
        L.error(f"{repr(resp)} does not match schema {repr(schema)} at {schema_path}")
        return False
    elif schema["type"] == "array":
        if "items" not in schema:
            L.error(f"Schema for array at {schema_path} does not specify items!")
            return False
        item_schema = schema["items"]
        if not isinstance(resp, list):
            L.error(f"Server did not return a list for {schema_path} (typed as array in schema)")
            return False
        for i, item in enumerate(resp):
            if not does_response_fit_schema(posixpath.join(schema_path, str(i)), item_schema, item):
                success = False
    else:
        L.error(f"Invalid swagger type {schema['type']} for {type(resp)} at {schema_path}")
        print(json.dumps(schema, indent=2))
        return False
    return success


class GetPath(object):
    def __init__(self, url, spec):
        self.url = url
        self.req_params = {}
        self.opt_params = {}
        self.success = None
        self.failures = {}
        if 'parameters' in spec.keys():
            for p in spec['parameters']:
                name = p['name']
                req = p.get('required', False)
                target = self.req_params if req else self.opt_params
                target[name] = Param(name, p['in'], p['type'])
                if 'default' in p:
                    defs = p['default']
                    if isinstance(defs, list):
                        for d in defs:
                            target[name].values.add(d)
                    else:
                        target[name].values.add(defs)
                if 'enum' in p:
                    for v in p['enum']:
                        target[name].values.add(v)
                if req and len(target[name].values) == 0:
                    print(f"FAIL: No default values in swagger for required parameter {name} in {self.url}")
        for code, schema in spec['responses'].items():
            if code[0] == "2" and 'schema' in schema:
                self.success = schema['schema']
            elif code[0] == "2":
                L.error(f"2xx response with no schema in {self.url}")
            else:
                self.failures[code] = schema

    def generate_success(self, host):
        url_args = "&".join([f"{p.name}={some(p.values)}" for p in self.req_params.values()])
        base_url = urllib.parse.urljoin(host, self.url)
        test_url = f"{base_url}?{url_args}"
        if url_filter.match(test_url):
            try:
                resp = requests.get(url=test_url, verify=(not args.tls_no_verify))
                self.validate(test_url, resp, True)
            except Exception as e:
                L.error(f"Network failure in test {e}")
        else:
            L.debug(f"url_filter skips {test_url}")

    def generate_failure(self, host):
        all_params = list(self.req_params.values()) + list(self.opt_params.values())
        bad_param = ''.join([random.choice(string.ascii_lowercase) for _ in range(5)])
        while bad_param in all_params:
            bad_param = ''.join([random.choice(string.ascii_lowercase) for _ in range(5)])
        all_params.append(Param(bad_param, "query", "string"))
        url_args = "&".join([f"{p.name}={not_some(p.values)}" for p in all_params])
        base_url = urllib.parse.urljoin(host, self.url)
        test_url = f"{base_url}?{url_args}"
        if url_filter.match(test_url):
            try:
                resp = requests.get(url=test_url, verify=(not args.tls_no_verify))
                self.validate(test_url, resp, False)
            except Exception as e:
                L.error(f"Network failure in test {e}")

    def validate(self, test_url, resp, expect_success):
        try:
            resp_json = json.loads(resp.text)
        except json.decoder.JSONDecodeError as e:
            L.error(f"Non-json response from {test_url}")
            return
        success_code = resp.status_code >= 200 and resp.status_code < 300
        if success_code and expect_success:
            if self.success is not None:
                if does_response_fit_schema(posixpath.join(self.url, str(resp.status_code)), self.success, resp_json):
                    L.info(f"tested {test_url}")
                else:
                    L.error(f"tested {test_url}")
            else:
                L.error(f"Missing schema {test_url}")
        elif not success_code and not expect_success:
            schema = self.failures.get(str(resp.status_code), None)
            if schema is not None:
                if does_response_fit_schema(posixpath.join(self.url, str(resp.status_code)), schema, resp_json):
                    L.info(f"tested {test_url}")
                else:
                    L.error(f"tested {test_url}")
            else:
                L.error("Missing schema for {resp.status_code} from {test_url}")
        else:
            L.error(f"Received incorrect status code {resp.status_code} against {test_url}")


def get_the_spec(url):
    if url[:7] == "file://":
        with open(url[7:]) as f:
            return f.read()
    return requests.get(url=url).text


# Swagger paths look absolute but they are relative to the base.
def not_absolute(path):
    return path[1:] if path[0] == '/' else path


def find_ref(spec, path):
    if len(path) > 0 and path[0] == '#':
        return find_ref(spec, path[1:])
    if len(path) == 1:
        return spec[path[0]]
    return find_ref(spec[path[0]], path[1:])


def resolve_refs(spec, spec_root=None):
    '''Find all "$ref" keys in the swagger spec and inline their target schemas.

       As with all inliners this will break if a definition recursively links to itself, but this should not
       happen in swagger as embedding a structure inside itself would produce a record of infinite size.'''
    if spec_root is None:
        spec_root = spec
    newspec = {}
    for k, v in spec.items():
        if k == "$ref":
            path = v.split('/')
            target = find_ref(spec_root, path)
            # Unfold one level of the tree and erase the $ref if possible.
            if isinstance(target, dict):
                for kk, vv in resolve_refs(target, spec_root).items():
                    newspec[kk] = vv
            else:
                newspec[k] = target
        elif isinstance(v, dict):
            newspec[k] = resolve_refs(v, spec_root)
        else:
            newspec[k] = v
    # This is an artifact of inline the $refs when they are inside a properties key as their children should be
    # pushed up into the parent dictionary. They must be merged (union) rather than replace as we use this to
    # implement polymorphism in the data-model.
    if 'properties' in newspec and isinstance(newspec['properties'], dict) and \
       'properties' in newspec['properties']:
        sub = newspec['properties']['properties']
        del newspec['properties']['properties']
        if 'type' in newspec['properties']:
            del newspec['properties']['type']
        for k, v in sub.items():
            newspec['properties'][k] = v
    return newspec


#######################################################################################################################
# Initialization

random.seed(7)      # Default is reproducible sequences

parser = argparse.ArgumentParser()
parser.add_argument('--url', type=str,
                    default='https://raw.githubusercontent.com/netdata/netdata/master/web/api/netdata-swagger.json',
                    help='The URL of the API definition in swagger. The default will pull the latest version '
                         'from the main branch.')
parser.add_argument('--host', type=str,
                    help='The URL of the target host to fuzz. The default will read the host from the swagger '
                         'definition.')
parser.add_argument('--reseed', action='store_true',
                    help="Pick a random seed for the PRNG. The default uses a constant seed for reproducibility.")
parser.add_argument('--passes', action='store_true',
                    help="Log information about tests that pass")
parser.add_argument('--detail', action='store_true',
                    help="Log information about the response/schema comparisons during each test")
parser.add_argument('--filter', type=str,
                    default=".*",
                    help="Supply a regex used to filter the testing URLs generated")
parser.add_argument('--tls-no-verify', action='store_true',
                    help="Disable TLS certification verification to allow connection to hosts that use"
                         "self-signed certificates")
parser.add_argument('--dump-inlined', action='store_true',
                    help='Dump the inlined swagger spec instead of fuzzing. For "reasons".')

args = parser.parse_args()
if args.reseed:
    random.seed()

spec = json.loads(get_the_spec(args.url))
inlined_spec = resolve_refs(spec)
if args.dump_inlined:
    print(json.dumps(inlined_spec, indent=2))
    sys.exit(-1)

logging.addLevelName(40, "FAIL")
logging.addLevelName(20, "PASS")
logging.addLevelName(10, "DETAIL")
L = logging.getLogger()
handler = logging.StreamHandler(sys.stdout)
if not args.passes and not args.detail:
    L.setLevel(logging.ERROR)
elif args.passes and not args.detail:
    L.setLevel(logging.INFO)
elif args.detail:
    L.setLevel(logging.DEBUG)
handler.setFormatter(logging.Formatter(fmt="%(levelname)s %(message)s"))
L.addHandler(handler)

url_filter = re.compile(args.filter)

if spec['swagger'] != '2.0':
    L.error(f"Unexpected swagger version")
    sys.exit(-1)
L.info(f"Fuzzing {spec['info']['title']} / {spec['info']['version']}")

host, base_url = build_url(args.host or spec['host'], inlined_spec['basePath'])

L.info(f"Target host is {base_url}")
paths = []
for name, p in inlined_spec['paths'].items():
    if 'get' in p:
        name = not_absolute(name)
        paths.append(GetPath(posixpath.join(base_url, name), p['get']))
    elif 'put' in p:
        L.error(f"Generation of PUT methods (for {name} is unimplemented")

for s in inlined_spec['schemes']:
    for p in paths:
        resp = p.generate_success(s + "://" + host)
        resp = p.generate_failure(s+"://"+host)