Network Programming-Project 3 Solved

1             Introduction
The project is divided into two parts. This is the first part of the project.

Here, you are asked to write a simple HTTP server called http server and a CGI program console.cgi. We will use Boost.Asio library to accomplish this project.

2             Specification
2.1           http server
1.    In this project, the URI of HTTP requests will always be in the form of /${cgi name}.cgi (e.g., /panel.cgi, /console.cgi, /printenv.cgi), and we will only test for the HTTP GET method.

2.    Your http server should parse the HTTP headers and follow the CGI procedure (fork, set environment variables, dup, exec) to execute the specified CGI program.

3.    The following environment variables are required to set:

(a)    REQUESTMETHOD

(b)    REQUEST URI

(c)     QUERY STRING

(d)    SERVER PROTOCOL

(e)    HTTP HOST

(f)      SERVER ADDR

(g)    SERVER PORT

(h)    REMOTEADDR

(i)      REMOTE PORT

For instance, if the HTTP request looks like:

GET /console.cgi?h0=nplinux1.cs.nctu.edu.tw&p0= ... (too long, ignored)

Host: nplinux8.cs.nctu.edu.tw:7779

User-Agent: Mozilla/5.0

Accept: text/html,application/xhtml+xml,applica ... (too long, ignored)

Accept-Language: en-US,en;q=0.8,zh-TW;q=0.5,zh; ... (too long, ignored)

Accept-Encoding: gzip, deflate

DNT: 1

Connection: keep-alive

Upgrade-Insecure-Requests: 1

Then before executing console.cgi, you need to set the corresponding environment variables. In this case, REQUEST METHOD should be ”GET”, HTTP HOST should be

”nplinux8.cs.nctu.edu.tw:7779”, and so on and so forth.

2.2           console.cgi
1.        You are highly recommended to inspect and run the CGI samples before you start this section. For details about CGI (Common Gateway Interface), please refer to the course slides as well as the given CGI examples.

2.        The console.cgi should parse the connection information (e.g. host, port, file) from the environment variable QUERY STRING, which is set by your HTTP server (see section 2.1).

For example, if QUERY STRING is:

h0=nplinux1.cs.nctu.edu.tw&p0=1234&f0=t1.txt&h1=nplinux2.cs.nctu.edu.tw& p1=5678&f1=t2.txt&h2=&p2=&f2=&h3=&p3=&f3=&h4=&p4=&f4=

It should be understood as:

h0=nplinux1.cs.nctu.edu.tw
# the hostname of the 1st server
p0=1234
# the port of the 1st server
f0=t1.txt
# the file to open
h1=nplinux2.cs.nctu.edu.tw
# the hostname of the 2nd server
p1=5678
# the port of the 2nd server
f1=t2.txt
# the file to open
h2=
# no 3rd server, so this field is empty
p2=
# no 3rd server, so this field is empty
f2=
# no 3rd server, so this field is empty
h3=
# no 4th server, so this field is empty
p3=
# no 4th server, so this field is empty
f3=
# no 4th server, so this field is empty
h4=
# no 5th server, so this field is empty
p4=
# no 5th server, so this field is empty
f4=
# no 5th server, so this field is empty
3.        After parsing, console.cgi should connect to these servers. Note that the maximum number of the servers never exceeds 5.

4.        If we select N sessions, then you can assume them to be session 1 to session N.

For example, we will NOT select session 1 + session 3 but skip session 2 during demo.

5.        For the selected sessions, you can assume host, port, and file fields will NOT be empty.

6.        The remote servers that console.cgi connects to are Remote Working Ground Servers with shell prompt ”% ” (NP Project2), and the files (e.g., t1.txt) contain the commands for the remote shells.

However, you should not send the entire file to the remote server and execute them all at once.

Instead, send one line whenever you receive a shell prompt ”% ” from remote.

(You can assume the output of all commands will NOT contain ”%”)

7.        Your console.cgi should display the hostname and the port of the connected remote server at the top of each session.

8.        Your console.cgi should display the remote server’s replies in real-time. Everything you send to remote or receive from remote should be displayed on the web page as soon as possible.

For example:

% ls

bin test.html

Here, the blue part is the content (output) you received from the remote shell, and the brown part is the content (command) you sent to the remote. The output order matters and needs to be preserved. You should make sure that commands are displayed right after the shell prompt ”% ”, but before the execution result received from remote.

9.        You should NOT change the order of outputs received from the remote servers. Besides, DO NOT add delay between commands.

10.    Regarding how to display the server’s reply (console.cgi), please refer to sample console.cgi. Since we will not judge your answers with diff for this project, feel free to modify the layout of the web page. Just make sure you follow the below rules:

(a)    Each session should be separated.

(b)    The commands and the outputs of the shell are displayed in the right order and at the right time

(c)     The commands can be easily distinguished from the outputs of the shell.

2.3           panel.cgi (Provided by TA)
1. This CGI program generates the form in the web page. It detects all files in the directory test  case/ and display them in the selection menu.

2.4           test case/ (Provided by TA)
1. This directory contains test cases, and each of which lists the commands to run remotely. You can put new test cases into this directory, and select it in the form generated by panel.cgi.

2.5           np single golden (Provided by TA)
1. This executable file is a Remote Working Ground Server in project2. We will use it for demo. You do NOT need to use your code for this server.

2.6           The Execution Flow
2.6.1      Initial Setup

The structure of your working directory:

working_dir

|-- http_server

|-- console.cgi

|-- panel.cgi

|-- test_case/

2.6.2      Execution

1.    Run your http server by ./http server [port]

2.    Open a browser and visit http://[NP_server_host]:[port]/panel.cgi

3.    Fill the form with the servers to connect to and select the input file, then click Run.

4.    The web page will automatically redirected to http://[NP_server_host]:[port]/console.cgi and your console.cgi should start now.

3             Requirements
1.    You need to implement two programs in this part: http server and console.cgi.

Every function that touches network operations (e.g., DNS query, connect, accept, send, receive) MUST be implemented using the library Boost.Asio. Directly using low-level system calls such as ‘read‘, ‘write‘, ‘listen‘, are thereby NOT allowed.

2.    All of the network operations should implement in non-blocking (asynchronous) approaches.

3.    You must provide Makefile. After typing command ”make part1”, two executables named http  server and console.cgi should be generated. The executables should be placed in the top layer of the directory.

4.    You can only use C/C++ to implement this project. Except for Boost, other third-party libraries are NOT allowed.


2.    Bitbucket:

(a)     Create a private repository named as [your student ID]  np project3 (e.g., 310550000 np project3) inside the nctu np 2022 team, place it under the project np project3, and set the ownership to nctu np 2022.

(b)    You can push anything you need to Bitbucket, but please make sure to commit at least 5 times.

3.    We take plagiarism seriously.

All projects will be checked by a cutting-edge plagiarism detector.

You will get zero points on this project for plagiarism. Please don’t copy-paste any code from the internet, this may be considered plagiarism as well.

Protect your code from being stolen.

5             Notes
1.    NP project should be run on NP servers, otherwise, your account may be locked.

2.    Any abuse of NP server will be recorded.

3.    Don’t leave any zombie processes in the system.

4.    You will lose points for violating any of the rules mentioned in this spec.

5.    Enjoy the project!

6             Hints and Reminders
1.    The version of Boost Library is 1.77.0 in nplinux server.

2.    You can use the HTTP server that already hosted on NP servers to test your CGI programs. Simply put all of the CGI programs as well as test case/ into ∼/public html, and then visit http://[NP_server_host]/~[your_user_name]/[your_cgi_name].cgi.

Note that:

•    The filenames of CGI programs MUST end with .cgi.

•    ∼/public html is a directory named ”public  html” in your home directory. Manually create it if it does not exist.

3.    You can use the command nc to inspect the HTTP request sent from browser:

•    Execute the command nc -l [port] on one of the NP servers (e.g., run nc -l 8888 on nplinux3)

•    Open a browser and type http://[host]:[port] in the URL. You can add some query parameters and check the result. For example, http://nplinux3.cs.nctu.edu.tw:8888/test.cgi?a=b&c=d