MySQL Bugs: #91974: mysql-connector-python crashes on 0 time value

Bug #91974	mysql-connector-python crashes on 0 time value
Submitted:	11 Aug 2018 0:13	Modified:	10 Aug 2022 20:52
Reporter:	Robert Walzer	Email Updates:
Status:	Closed	Impact on me:	None
Category:	Connector / Python	Severity:	S3 (Non-critical)
Version:	8.0.12	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
The mysql-python-connector binary protocol appears to crash on time value of 0 because it does not deal with payload of size 0 correctly. According to the documentation(https://dev.mysql.com/doc/internals/en/binary-protocol-value.html) time of 00:00.0 can be compressed to size 0 in the packet. The connector yields this crash when reading this value though:

```
Traceback (most recent call last):
  File "script_tests/binary.py", line 14, in <module>
    q("select * from db.t")
  File "script_tests/binary.py", line 7, in q
    for r in c:
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/cursor.py", line 1249, in fetchone
    return self._fetch_row() or None
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/cursor.py", line 851, in _fetch_row
    binary=self._binary, columns=self.description, raw=raw)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/connection.py", line 465, in get_row
    raw=raw)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/connection.py", line 491, in get_rows
    self._socket, columns, count, charset)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/protocol.py", line 478, in read_binary_result
    values = self._parse_binary_values(columns, packet[5:], charset)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/protocol.py", line 450, in _parse_binary_values
    (packet, value) = self._parse_binary_time(packet, field)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/protocol.py", line 415, in _parse_binary_time
    days = struct_unpack('I', data[1:5])[0]
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/catch23.py", line 91, in struct_unpack
    return struct.unpack_from(fmt, buffer(buf))
struct.error: unpack_from requires a buffer of at least 4 bytes
```

How to repeat:
```
import mysql.connector
from mysql.connector.cursor import MySQLCursorPrepared

def q(query):
    c = cnx.cursor(cursor_class=MySQLCursorPrepared)
    c.execute(query)
    for r in c:
        print r

cnx = mysql.connector.connect(user='root', database='',port=3306,use_pure=True)
q("create database db")
q("create table db.t(a time)")
q("insert into db.t values(0)")
q("select * from db.t")
```

Hello Robert,

Thank you for the report and test case!

thanks,
Umesh

I have another test case which causes the connector to crash on a binary column. Would you like me to file a separate bug for this:

  File "script_tests/binary.py", line 14, in <module>
    q("select * from db.t")
  File "script_tests/binary.py", line 7, in q
    for r in c:
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/cursor.py", line 1249, in fetchone
    return self._fetch_row() or None
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/cursor.py", line 851, in _fetch_row
    binary=self._binary, columns=self.description, raw=raw)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/connection.py", line 465, in get_row
    raw=raw)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/connection.py", line 491, in get_rows
    self._socket, columns, count, charset)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/protocol.py", line 478, in read_binary_result
    values = self._parse_binary_values(columns, packet[5:], charset)
  File "/usr/local/lib/python2.7/dist-packages/mysql/connector/protocol.py", line 454, in _parse_binary_values
    values.append(value.decode(charset))
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xd0 in position 2: invalid continuation byte

repro:
def q(query):
    c = cnx.cursor(cursor_class=MySQLCursorPrepared)
    c.execute(query)
    for r in c:
        print r

cnx = mysql.connector.connect(user='root', database='',port=3306,use_pure=True)
q("create database db")
q("create table db.t(a binary(16))")
q("insert into db.t values(unhex('D0BFD000000000000000000000000000'))")
q("select * from db.t")

Posted by developer:
 
Patch submitted for review.

Posted by developer:
 
Fixed as of the upcoming MySQL Connector/Python 8.0.31 release, and here's the proposed changelog entry from the documentation team:

The binary protocol would unexpectedly halt when given a time value of 0.
The expected behavior is to receive a 00:00:00 time when given a 0-time
value payload.

Thank you for the bug report.