Python sql注入 过滤字符串的非法字符实例

#coding:utf8
#在开发过程中，要对前端传过来的数据进行验证，防止sql注入攻击，其中的一个方案就是过滤用户传过来的非法的字符


def sql_filter(sql, max_length=20):
 dirty_stuff = ["\"", "\\", "/", "*", "'", "=", "-", "#", ";", "<", ">", "+", "%", "$", "(", ")", "%", "@","!"]
 for stuff in dirty_stuff:
  sql = sql.replace(stuff, "")
 return sql[:max_length]


username = "1234567890!@#!@#!@#$%======$%"

username = sql_filter(username) # SQL注入
print username

# 输出结果是:1234567890

cur=db.cursor()
sql = "INSERT INTO test2(cid, author, content) VALUES (1, '1', 'aa')"
cur.execute(sql,())

cur=db.cursor()
sql = "INSERT INTO test2(cid, author, content) VALUES (%s, '%s', '%s')"
sql=sql%('2','2','bb')
cur.execute(sql,())

cur=db.cursor()
sql = "INSERT INTO test2(cid, author, content) VALUES (%s, %s, %s)"
cur.execute(sql,('3','3','c%c'))