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
|
# coding=utf-8
import uuid
import threading # multiprocessing.managers.BaseManager uses threading to serve incoming requests
import hashlib
import base64
import random
from . import prolog_session
from . import python_session
from . import problems
from . import handlers
import db
from errors.session import NoSuchSession, AuthenticationFailed
import psycopg2.extras
__all__ = ['get_session_by_id', 'get_or_create_session', 'UserSession']
sessions = {} # maps session IDs to session objects
module_access_lock = threading.Lock() # use this lock to access the sessions dictionary
class UserSession(object):
"""Abstracts a user session.
Only public methods are available to the outside world due to the use of multiprocessing managers.
Therefore prefix any private methods with an underscore (_).
No properties are accessible; use getters and setters instead.
Values are passed by value instead of by reference (deep copy!).
"""
def __init__(self, uid, username):
self._access_lock = threading.Lock()
self.sid = uuid.uuid4().hex
self.uid = uid
self.username = username
self.prolog_session = None
self.python_session = None
def destroy(self):
"""Destroys the session."""
with self._access_lock:
with module_access_lock:
del sessions[self.sid]
if self.prolog_session is not None:
self.prolog_session.end()
self.prolog_session = None
if self.python_session is not None:
self.python_session.destroy()
self.python_session = None
# TODO: add any cleanups as features are added!
def get_sid(self):
return self.sid
def get_uid(self):
return self.uid
def get_prolog(self):
with self._access_lock:
if self.prolog_session is None:
self.prolog_session = prolog_session.PrologSession() # lazy init
return self.prolog_session
def get_python(self):
with self._access_lock:
if self.python_session is None:
self.python_session = python_session.PythonSession() # lazy init
return self.python_session
def get_problem_data(self, language, problem_group, problem):
mod = problems.load_problem(language, problem_group, problem, 'sl')
mod_language = problems.load_language(language, 'sl')
# Get generic and problem-specific hints.
hint = dict(mod_language.hint)
hint.update(mod.hint)
conn = db.get_connection()
try:
cur = conn.cursor()
try:
cur.execute("select l.id, l.name, g.id, g.name, p.id, p.name from problem p inner join language l on l.id = p.language_id inner join problem_group g on g.id = p.problem_group_id where l.identifier = %s and g.identifier = %s and p.identifier = %s", (language, problem_group, problem))
row = cur.fetchone()
problem_id = row[4]
result = {
'language': {'id': row[0], 'identifier': language, 'name': row[1]},
'problem_group': {'id': row[2], 'identifier': problem_group, 'name': row[3]},
'problem': {'id': problem_id, 'identifier': problem, 'name': row[5], 'slug': mod.slug, 'description': mod.description, 'hint': hint}
}
cur.execute("select content from solution where problem_id = %s and codeq_user_id = %s", (problem_id, self.uid))
row = cur.fetchone()
if row:
result['solution'] = row[0]
else:
result['solution'] = ''
return result
finally:
cur.close()
finally:
conn.commit()
db.return_connection(conn)
def update_solution(self, problem_id, trace, solution):
if (trace is None) and (solution is None):
return
conn = db.get_connection()
try:
cur = conn.cursor()
try:
# TODO: convert to upsert with postgresql 9.5 to eliminate the small window where it's possible for more than one concurrent insert to execute
cur.execute('select id, trace, content from solution where codeq_user_id = %s and problem_id = %s for update', (self.uid, problem_id))
row = cur.fetchone()
if row:
if row[1]:
new_trace = row[1]
if trace:
new_trace.extend(trace)
else:
new_trace = trace
new_solution = row[2] if solution is None else solution
cur.execute('update solution set content = %s, trace = %s where id = %s', (new_solution, psycopg2.extras.Json(new_trace), row[0]))
else:
# this is the first entry
cur.execute('insert into solution (done, content, problem_id, codeq_user_id, trace) values (%s, %s, %s, %s, %s)', (False, solution, problem_id, self.uid, psycopg2.extras.Json(trace)))
finally:
cur.close()
conn.commit()
except:
conn.rollback()
raise
finally:
db.return_connection(conn)
def send(self, json_obj):
"""Sends a message to the user.
This method may be used only for messages that are not replies to requests.
For replies use the reply() method on the Request object.
:param json_obj: a dict representing the json message
:return: None
"""
json_obj['sid'] = self.sid
handlers.send(None, self.sid, json_obj)
def __del__(self):
# no locking needed if GC is removing us, as there cannot be any concurrent access by definition
if hasattr(self, 'prolog_session') and (self.prolog_session is not None):
self.prolog_session.end()
self.prolog_session = None
if hasattr(self, 'python_session') and (self.python_session is not None):
self.python_session.destroy()
self.python_session = None
# TODO: add any cleanups as features are added!
def get_session_by_id(sid):
with module_access_lock:
s = sessions.get(sid, None)
if s is None:
raise NoSuchSession('There is no session with SID {}'.format(sid))
return s
def get_or_create_session(uid, username, sid=None):
with module_access_lock:
if sid is not None:
s = sessions.get(sid)
if s is not None:
return s
s = UserSession(uid, username)
sessions[s.sid] = s
return s
def authenticate_and_create_session(username, password):
conn = db.get_connection()
try:
cur = conn.cursor()
try:
cur.execute('select id, password from codeq_user where username = %s', (username,))
row = cur.fetchone()
if row is None:
raise AuthenticationFailed('No such user: {}'.format(username))
if verify_password(password, row[1]):
return get_or_create_session(row[0], username)
raise AuthenticationFailed('Password mismatch')
finally:
cur.close()
finally:
conn.commit()
db.return_connection(conn)
def verify_password(plain_password, encrypted_password):
elts = encrypted_password.split('$')
if len(elts) != 4:
return False
if elts[0] != 'pbkdf2_sha256':
return False
try:
rounds = int(elts[1])
except:
return False
enc = hashlib.pbkdf2_hmac('sha256', plain_password.encode('utf-8'), elts[2].encode('utf-8'), rounds)
return base64.b64encode(enc).decode('utf-8') == elts[3]
_salt_chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
_salt_chars_len = len(_salt_chars)
def encrypt_password(plain_password):
rounds = 20000
chosen_chars = []
for i in range(0, 12):
chosen_chars.append(_salt_chars[random.randrange(0, _salt_chars_len)])
salt = ''.join(chosen_chars)
enc = hashlib.pbkdf2_hmac('sha256', plain_password.encode('utf-8'), salt.encode('utf-8'), rounds)
return '{0}${1}${2}${3}'.format('pbkdf2_sha256', rounds, salt, base64.b64encode(enc).decode('utf-8'))
random.seed()
# TODO: add a session timeout timer
|
