Sample questions

HTML
1. Why is HTML validation recommended?
2. Label every component of the following HTML element (Some of the possible labels are
attributes, values, content, start/end tag, etc.).
<a href=“links.html”>Useful links </a>
3. Give an example where an absolute link is more appropriate to use than a relative link.
4. Correct any invalid HTML 5 syntax:
a)
<!DOCTYPE html>

<html>
<body>
<h1> Welcome to <b> SY306! </h1> </b>
<h2> Today’s Agenda </h2>
<li> HTML5
<li> JavaScript
</body>
b) <!DOCTYPE htm>
<html>
<title>Internet and WWW How to Program - Welcome</title>
<body>
<img scr = "xmlhtp.jpg" height = "238" width = "183" >
<h1 align=“center”>Under construction</h1>
</body>
</html>
c)
<html>
<head>
<title>Internet and WWW How to Program - Links</title>
</head>
<body>
<b> <h1>Here are my favorite links</h1> </b>
<p><A href = "http://www.yahoo.com">Yahoo!</A></p>
<p><A mailto = "[email protected]">Webmaster</A></p>
</body>
</html>
d)
<!DOCTYPE html>
<html>
<head> <title>Best features of the Internet</title> </head>
<body>
<ul>
<li>Meet new people from around the world.</li>
<li>Access to new media as it becomes public: </li>
<ul>
<li>New games</li>
<li>New applications & software
</ul>
<li>Search engines</li>
</ul> </body>
</html>
5. Write the code to generate this table:
a)
b)
c)
6. What kind of security each of the following provides:
Using <input type=“password”>
Using <input type=“hidden”>
Using https://
Using http://
7. Write the code to generate this form – the script to execute when the form is submitted is
confirm.py:
8. Write the code to generate this form – the script to execute when the form is submitted is
search.py:
CSS
9. What is a clickJacking attack?
10. Write an external stylesheet styles.css that makes every h1 element centered; apply the
stylesheet to starter.html
11. Write an embedded stylesheet that will:
Make every <h1> and <h2> section have 20pt size text
Put lines above all links instead of under them
Define a generic selector called “cat" that will italicize text
12. Write an external stylesheet that will:
Using some relative size, make all <h3> text twice as large as <h4> text
Make normal paragraphs that are nested inside a table appear in bold.
13. Where is the syntax bug in the following code:
/* styles.css */
td
{background-color: green; color: white}
th
{background-color: green; color: red}
a
{font-weight: bold; text-decoration: none}
table {margin-left: 5em, border-style: groove,
border-width: thick}
div
{border-style: inset; border-width: thick}
.crazy {color: yellow; font-weight:700}
.mild {color: gray; text-decoration: underline}
14. What attributes does the <p> get assigned?
<style type = “text/css”>
body { font-weight: bold }
td { font-size: 14pt; font-color: green }
.cool { font-color: red }
p { font-size: 12pt }
td p { text-decoration: underline; font-color: yellow }
</style>
<table><tr>
<td><p class=“cool”>Let’s get it started</p></td>
</tr></table>
15. Draw the output rendered by the browser when the following code is executed:
<head>
<style type=“text/css”>
.pane { float:right; width:20%; height:600px; border:1px solid black }
.header { width:75%; height:100px; border:1px solid black }
.main { width:75%; height:500px; border:1px solid black }
</style>
</head>
<body>
<div class=“pane”> some content </div>
<div class=“header”> the header </div>
<div class=“main”> the main body </div>
</body>
JavaScript
16. What is the output of the following JavaScript program:
a)
var x, y, z;
x = 7;
y = 9;
z = "abc";
window.alert(x+y+z);
window.alert(z+y+x);
if (x)
window.alert("x true");
x = "seven";
window.alert(x+y+z);
b)
var a, b, c;
a = 1;
b = 2;
c = 3;
d = a + b * c;
window.alert("<h1>Begin</h1>");
if (d < 20)
window.alert("d is okay: "+d);
else
window.alert("d is too high!:"+ d);
d = d - 3;
document.writeln("<h1>Done. Final d = "+d+"</h1>");
17. Write a JavaScript snippet to read in a number from the user and output its
absolute value.
18. Write a JavaScript snippet to read in three numbers x, y, z and output them in
sorted order.
19. Consider the following code:
/* Return an integer no larger than ‘max’ */
var max = 25;
var value;
do {
value = window.prompt(
"Please enter an integer no larger than "+max);
} while (value > max);
a) What is the purpose of this code?
b) When does this code work, and why?
c) When does it fail and how do you fix it?
20. What is the output of the following JavaScript program?
a)
function dog(g) {
h = 3;
var sum = g+h;
document.write("<br> Sum is: "+sum);
}
g = 7;
h = 5;
document.writeln("<br> g: "+g+" h: "+h);
dog(g);
document.writeln("<br> g: "+g+" h: "+h);
document.writeln("<br> sum: "+sum);
document.writeln(“<br> End of script");
b)
function fun1 (x) {
x = x + 3;
y = y + 4;
document.writeln("<br> FUN1: "+x+ "," +y);
}
function fun2 () {
var y;
x = x + 10;
y = y + 20;
document.writeln("<br> FUN2: "+x+ "," +y);
}
x = 1;
y = 2;
document.writeln("<br> MAIN #1: "+x+ "," +y);
fun1(x);
document.writeln("<br> MAIN #2: "+x+ "," +y);
fun1(y);
document.writeln("<br> MAIN #3: "+x+ "," +y);
fun2();
document.writeln("<br> MAIN #4: "+x+ "," +y);
c)
function printme( z ) {
document.writeln("<br> z is ",z);
}
var array1 = [17, 21, 42];
var array2 = [14, 19];
var x = 1;
printme (array1);
printme (array2[1]);
printme (x);
array1[x] = 57;
printme (array1);
21. Write a function that takes two arguments and returns the minimum of the two;
write code to invoke the function
22. a) Write a function “sumArray” as follows:
Input: an array
Output: the sum of that array
b.) Write test code to create an array and call “sumArray” on it.
DHTML
23. Change this code to make the <p> element have a large font when you move the
mouse over it.
<!DOCTYPE html>
<html>
<head> <meta charset = “utf-8” />
<title>Bigger</title>
<script type = "text/javascript">
</script>
</head>
<body>
<p>
Welcome to my page!
</p>
</body>
</html>
24. Modify the code below so that clicking on the button changes target of <a>
element to “dog.html”
<!DOCTYPE html>
<html><head>
<meta charset = "utf-8" />
<title>Change Link</title>
<script type = "text/javascript">
</script>
</head>
<body>
<p><a href="cat.html">See some animals!</a></p>
<form>
<input type="button" value="Change animal“ />
</form>
</body> </html>
25. Write a form to read in a password from the user in two boxes. When they
submit the form, proceed only if the passwords are the same.
Regular Expressions
26. Write the expression to replace one or more newline characters in a string with
“&&”.
Make it work for both Unix (\n) and Windows (\r\n)
27. What are some common uses of regular expressions in web programming?
Cookies – third party cookies
28. What are cookies; how do they work?
29. What are 3rd party cookies?
Python and CGI:
30. Write Python script that will, given the URL provided below, generate HTML that
looks like the screenshot
http://mope.academy.usna.edu/~alice/sy306/ice/ex1.py?maxNumber=5
31. Write a Python script that accepts two numbers from browser user, prints error if
num2 is zero, otherwise outputs num1/num2.
Cookies:
32. JS: Ask user for favorite quote using a window prompt. Save quote in a cookie
identified by “favQuote”. Display quote on the page using an alert.
33. JS: Read the value of cookie identified by “favQuote” and display it in a pop-up
msg if it exists, otherwise display “no quotes”
34. Python: Write a Python script to create a cookie with identifier “favQuote” and
content provided by user through CGI (param name “quote”). Output a
confirmation message to the user “quote was saved” displayed on the page.
Input validation, XSS attacks
35. What is a JavaScript injection?
36. Explain the steps of a typical reflective XSS attack.
37. Explain how input filtering can be used to prevent XSS attacks
SQL
38. Write the SQL to create the Enrolled table with the following schema:
Enrolled(Alpha, Cid, Semester, Grade)
Assume reasonable types for the columns. Primary keys are underlined, and
foreign keys are in italic
39. Write the SQL to update the grade of student with alpha 181234 enrolled in
SY306 during Spring2017 semester in the Enrolled table above. The new grade
is ‘A’.
40. Consider the table: Department(DeptName, ChairName, WebAddress, DivName)
Write the SQL query to find the name of the Chair of the ‘Math’ Department
41. Consider the table Students(Alpha, SName, Email, Major)
Write the SQL query to find the alpha and name of SCY or SIT students with ‘23’
somewhere in their email address. Display the results sorted by Alpha in
descending order.
42. Consider the tables:
Students(SNb, SName, Email)
Courses(Cid,CName, Dept)
Enrolled(SNb,Cid, Semester)
a) Find the student number and name for each student enrolled in ‘Spring2017’
semester
b) Find the names of all students enrolled in courses offered by the ‘ComSci’
department
SQL with Python
43. Consider the following tables and 2 files:
CREATE TABLE songs (
SongID int NOT NULL auto_increment,
Title varchar(30) NOT NULL,
Artist varchar(30) NOT NULL,
Votes int not null default 0,
Constraint PK_songs PRIMARY KEY (SongID)
);
song.py:
import mysql.connector
# Song class- adds, deletes, prints songs
class song:
# This class is used to create and maintain songs for the survey
def __init__(self):
pass
#add a song to the database
#songID is AUTO_INCREMENT and votes has a default of 0, so no need to worry
about them
def addSong(cursor, artist, title):
# TODO
#create query statement
#execute the query
#check number of rows affected > 0 if insert successful
#get the last songid inserted
#if insert successful (number of rows inserted > 0)
# return the songID (AUTO_INCREMENT key of song table) generated
#else return False
def printSongs(cursor):
query = "SELECT SongID, Artist, Title, Votes FROM songs ORDER BY Artist,
Title"
# query = "SELECT Artist FROM songs ORDER BY Artist, Title" # if only
one column returned, make sure we read it as a tuple of 1 element, which is
(col1,)
try:
cursor.execute(query)
except mysql.connector.Error as err:
#for DEBUG only we'll print the error and statement- we should print
some generic message instead for production site
print ('<p style = "color:red"')
print(err)
print (" for statement" + cursor.statement )
print ('</p>')
nbRows = 0
#create a table with results
table =
"<table><tr><th>SongID</th><th>Artist</th><th>Title</th><th>Votes</th></tr>\n
"
for (songID, artist, title, votes) in cursor:
# for (artist,) in cursor: #do something like this if only one column,
artist in the example, is returned - needs to be a tuple, so have the ,
table += "<tr><td>"+str(songID) + "</td><td>" +
artist+"</td><td>"+title+"</td><td>" + str(votes) + "</td></tr>\n"
nbRows+=1
table += "</table>"
if nbRows > 0:
return table
else:
return ""
songPage.py:
#!/usr/bin/env python3
import cgi,cgitb
cgitb.enable()
import mysql.connector
from mysql.connector import errorcode
from song import song
import config
print( "Content-type:text/html\n");
print ("""\
<!DOCTYPE html>
<html>
<head>
<meta charset = "utf-8">
<title>DB connection with Python</title>
</head>
<body>
""")
#connect to the database
try:
cnx = mysql.connector.connect(user=config.USER,
password = config.PASSWORD,
host = config.HOST,
database=config.DATABASE)
#check for errors
except mysql.connector.Error as err:
if err.errno == errorcode.ER_ACCESS_DENIED_ERROR:
print("Something is wrong with your user name or password")
elif err.errno == errorcode.ER_BAD_DB_ERROR:
print("Database does not exist")
else:
print(err)
print("<p>Fix your code or Contact your system admin</p></body></html>")
quit()
#create cursor to send queries
cursor = cnx.cursor()
#see if needed to insert data - get parameters from the form
params = cgi.FieldStorage()
insertButton = params.getvalue("insert")
#if insert button was pushed
if insertButton:
#get the artist and title from the form
artist = params.getvalue("artist")
title = params.getvalue("title")
#call the add song function in song to insert the song
result = song.addSong(cursor, artist, title)
#print either a confirmation message or error message
if result:
print ('<h2>New song with id ' + str(result) + ' inserted into the
database</h2>')
else:
print ('<h2>Could not insert the song</h2>')
#create the page
print ("<h1>Favorite songs</h1>")
print ('<form method = "post" action = "songPage_handout.py">')
#TODO: print a table with the songs from database, or "No songs in database"
message if there are no songs. Use the printSongs function in song
#print the inputs for getting the artist and title, and a submit button to
insert
print ("""\
<p>
<label>Artist: <input type = "text" name = "artist"></label><br>
<label>Title: <input type = "text" name = "title"></label><br>
<input type = "submit" name = "insert" value = "Insert song">
</p>""")
print ("</form>")
#close cursor since we don't use it anymore
cursor.close()
#commit the transaction
cnx.commit() #this is really important otherwise all changes lost
#close connection
cnx.close()
#print end html tags
print("</body></html>");
a) In songPage.py, complete the code to print the table of songs from the database,
by using the printSongs
method in the song class
b) In song.py, complete the code for the addSong() method to insert a song into the
database
Sessions
44. Complete the following code to create or continue a session that stores into a
session variable the time of last visit (which is the time the script is run):
#!/usr/bin/env python3
#from http://webpython.codepoint.net
import hashlib, time, os, shelve
from http import cookies
import cgitb;
cgitb.enable()
cookie = cookies.SimpleCookie()
string_cookie = os.environ.get('HTTP_COOKIE')
if not string_cookie:
#create session id and cookie
sid = hashlib.sha256(repr(time.time()).encode()).hexdigest()
cookie['sid'] = sid
message = 'New session'
else:
#read the cookie
cookie.load(string_cookie)
if 'sid' in cookie:
sid = cookie['sid'].value
else:
sid = hashlib.sha256(repr(time.time()).encode()).hexdigest()
cookie['sid'] = sid
message = 'New session'
cookie['sid']['expires'] = 12 * 30 * 24 * 60 * 60
#ICE print the cookie, content type line
# and start HTML file
# The shelve module will persist the session data
# and expose it as a dictionary
#create file name /tmp/sess_sid filename
#open shelve with that name; store in variable called "session"
#Retrieve last visit time from the session and print value
# Save the current time in the session
#close shelf (saves the session variables to disk)
SQL Injections:
45. Consider the following snippet of a Pyhton script that is executed when a user
submits a web form asking for username and password;
form = cgi.FieldStorage()
user =
pass =
result
“‘ AND
#if at
form.getvalue("username")
form.getvalue(“password”)
= cursor.query(“SELECT * FROM Users_Table WHERE name = ‘” + user +
passwd = ‘” + pass +”’”);
least one result, user allowed to login
a) Give the exact input that can be provided by a user such that the user can login
without having a valid username and password
Value for username field _________________________________________________
Value for password field______________________________________________
46. List one way or preventing SQL injections? Why is that method effective?
DB Security
47.
Write the SQL command to grant select privileges on your PRODUCT table to user
‘alice’
Will the user ‘alice’ be able to select from the PRODUCT table after you executed your
command?
Will the user “alice” be able to remove the PRODUCT table from your database?
Write the SQL command to remove the privileges to your PRODUCT table from the
user ‘alice’
HTTP/HTTPS protocol
48. Write the HTTP GET request generated when you enter
http://www.usna.edu/cs/news.html in the address bar of a browser and you hit
enter:
49. How do the HTTP request and response look like?
http://mope.academy.usna.edu/~adina/welcome.py?username=ac
welcome.py
#!/usr/bin/env python3
from http import cookies
import urllib.parse
import cgi
#get parameters
params = cgi.FieldStorage()
username = params.getvalue("username")
cookie = cookies.SimpleCookie()
cookie["Username"] = urllib.parse.quote(username)
print (cookie)
print( "Content-type:text/html\n");
print (<!DOCTYPE html>
<html><head><meta charset = "utf-8">
<title>Storing cookies with Python</title>
</head><body>""")
print ("<h1>Welcome "+ username + "</h1>");
print("</body></html>");
HTTP Request:
HTTP Response:
50. Assume that you are writing a login form and you need to submit the login
information securely (encrypted) The script to execute on the server is “login.py”.
The server is mope.academy.usna.edu.
What do you need to do, so the login information sent by the browser to the server, is
encrypted?
Cross-site Request Forgery (CSRF) attack
51. List the steps of a CSRF attack
52. What are the pre-requisites (what needs to happen) of a CSRF attack?
53. Describe what is “referrer validation”, in the context of CSRF attacks
54. Why referrer validation is not always preventing CSRF attacks?
55. Describe one method to prevent CSRF attacks
HTTP authentication
56. Is encryption used in the HTTP basic authentication?
57. Assume that the user is requesting the SecretFolder/secretFile.html that is
protected by basic http authentication. What is the HTTP Response header that a
browser will receive when first making the request?
58. Give one advantage and one disadvantage/problem of HTTP basic
authentication
59. Give one advantage and one disadvantage/problem of HTTP digest
authentication
60. Why is form-based authentication the most widely used method of authentication
for web applications?

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