Network代写：EE450 Socket Programming Project|留学生CS代写|代做Java编程|C作业|C++程序|Python代码

和往年作业一样，开发五个Server/Client，然后实现一个Web注册系统。

Objective

The objective of this assignment is to familiarize you with UNIX socket programming. It is an individual assignment and no collaborations are allowed. Any cheating will result in an automatic F in the course (not just in the assignment). If you have any doubts/questions, post your questions on D2L. You must discuss all project related issues on the Piazza discussion forum. We will give those who actively help others out by answering questions on the Piazza discussion forum up to 10 bonus points.

Problem Statement

Web registration system has been a critical system for USC students. It is the key place for students to plan their future course of study and plays an important role in students’ academic success. Imagine that one day the web registration system is gone and tens of thousands of students are left unknown about what to choose for the next semester. A course might be over-crowded with hundreds of students because students don’t know how many students have already registered and the administrator might have to randomly select hundreds of people to drop from that course. Or you can imagine on the first day of the semester, the web registration system is suddenly down, all students are anxiously refreshing their webpage. And another thing to consider is the security, keep in mind that our web registration system should have a kind of authorization, for example username and password. Otherwise, it will be a popular hoax among students to drop courses for others. Thus a secure, reliable, functional and informative web registration system is vital for our school. As a networking course, we will try to approach this problem with some simplification. We will make the assumption that only one student will access the web registration system each time, and there are only two departments of courses to choose from. We will also introduce a very simple authorization schema.

In this project, you will implement a simple web registration system for USC. Specifically, a student will use the client to access the central web registration server, which will forward their requests to the department servers in each department. For each department, the department server will store the information of the courses offered in this department. Additionally, a credential server will be used to verify the identity of the student.

There are total 5 communication end-points:

Client: used by a student to access the registration system.
Main server (serverM): coordinate with the backend servers.
Credential server (serverC): verify the identity of the student.
Department server(s) (serverCS and serverEE)): store the information of courses offered by this department.

For the backend servers, Credential server and Department servers will access corresponding files on disk, and respond to the request from the main server based on the file content. It is important to note that only the corresponding server should access the file. It is prohibited to access a file in the main server or other servers. We will use both TCP and UDP connections. However, we assume that all the UDP packages will be received without any error.

Source Code Files

Your implementation should include the source code files described below, for each component of the system.

ServerM (Main Server): You must name your code file: serverM.c or serverM.cc or serverM.cpp (all small letters except ‘M’). Also you must include the corresponding header file (if you have one; it is not mandatory) serverM.h (all small letters except ‘M’).
Backend-Servers C, CS and EE: You must use one of these names for this piece of code: server#.c or server#.cc or server#.cpp (all small letters except for #). Also you must include the corresponding header file (if you have one; it is not mandatory). server#.h (all small letters, except for #). The “#” character must be replaced by the server identifier (i.e. C or CS or EE), depending on the server it corresponds to. (e.g., serverC.cpp, serverEE.cpp & serverCS.cpp)
Note: You are not allowed to use one executable for all four servers (i.e. a “fork” based implementation).
Client: The name of this piece of code must be client.c or client.cc or client.cpp (all small letters) and the header file (if you have one; it is not mandatory) must be called client.h (all small letters).

Input Files

There are three input files that are given to the credential Server and two department servers and should be read by the server when it is up and running.

cred.txt: contains encrypted usernames and passwords. This file should only be accessed by the Credential server.
ee.txt: contains course information categorized in course code, credit, professor, days and course name. Different categories are separated by a comma. There could be space(s) or semicolons, except commas, in a category. One example is given below. This file should only be accessed by the EE Department server.
cs.txt: Same format as ee.txt. This file should only be accessed by the CS Department server.

Note: cred_unencrypted.txt is the unencrypted version of cred.txt, which is provided for your reference to enter a valid username and password. It should NOT be touched by any servers!!!

Application Workflow Phase Description

Phase 0

Please refer to the Process Flow section to start the main server, Credential server, EE
Department server, CS Department server and Client in order. Upon three backend servers (Credential server, CS Department server and EE Department server) are up and running, each backend server should read the corresponding file and store the information in a certain data structure. You can choose any data structure that accommodates the needs.

Phase 1

In this phase, you will be authenticating the credentials of the client. The client will be asked to enter the username and password on the terminal. The client will forward the request to the main server, and the main server will encrypt this information and again forward this request to the credential server. The credentials server would have all the encrypted credentials (both username and password would be encrypted) of the registered users, but it would not have any information about the encryption scheme. The information about the encryption scheme would only be present at the main server. The encryption scheme would be as follows:

Offset each character and/or digit by 4.
The scheme is case sensitive.
Special characters (including spaces and/or the decimal point) will not be encrypted or changed.

Phase 1A

Client sends the authentication request to the main server over TCP connection.
Constraints:

The username will be of lower case characters (5~50 chars).
The password will be case sensitive (5~50 chars).

Upon running the client using the following command, the user will be prompted to enter the username and password:

./client
Please enter the username: <unencrypted_username>
Please enter the password: <unencrypted_password>

This unencrypted information will be sent to the main server over TCP, the main server will encrypt this information and send it to the credential server, which takes us to phase-1B.

Phase 1B

Main server forwards the authentication request to the credentials server over UDP.

Phase 2

Phase 2A

serverC sends the result of the authentication request to serverM over a UDP connection.

In this phase we check the result of the authentication request sent to the serverC and communicate the result back to serverM. Once we receive the authentication request at serverC,

The authentication request will contain the encrypted form of the username and the password. At serverC, once the authentication request is received, the serverC should first check if the username in the authentication request matches with any of the usernames present in the cred.txt file. If the username exists, it secondly checks if the password in the authentication request is the same as the password corresponding to the same username in the cred.txt file (It should be a case-sensitive match). If both the checks are passed then serverC sends an authentication pass message to the serverM using UDP. If either of the conditions fail then the serverC sends an authentication fail message to the serverM (along with the reason for failure - username does not exist or password does not match). You can use any type of encoding to notify the main server that the authentication has passed or failed. For example: Send 0 to serverM to indicate that the authentication request has failed (no username), send 1 to serverM to indicate that the authentication request has failed (password does not match) and 2 to serverM to indicate that the authentication request has passed. Or PASS indicates that the authentication request has passed, FAIL_NO_USER indicates that the authentication request has failed (no username), and FAIL_PASS_NO_MATCH indicates that the authentication request has failed (password does not match).

Phase 2B

serverM sends the result of the authentication request to the client over a TCP connection.

The result of the authentication request (Pass or Fail-with reason) is sent to the client from the main server over TCP (any encoding can be used similar to Phase 2A) and the result is displayed on the client screen. Please check the on-screen messages section for further information. If the result of the authentication request is a failure then the client will have two more attempts to enter the correct username and password (a total of 3 attempts). If the authentication request fails (in the first or second attempt), Phases 1A, 1B, 2A and 2B have to be repeated. If all of the attempts fail then the client shuts down after indicating that all 3 attempts failed (Please check the on-screen messages section for further information). If the result of the authentication request is Pass then the client can move to Phase 3. The client shuts down only if all the 3 authentication attempts have failed. If any of the authentication attempts pass then the client stays on until it is manually shut down.

Phase 3

In this phase, you are required to implement sending the request from client to main server and then forwarding the request from the central registration to the backend server.

Phase 3A

In this part, you will implement the client sending a query to the central registration server. Your client should show a promote of
Please enter the course code to query:
Assuming the student entered:

EE450

And then the client program will promote:

Please enter the category (Credit / Professor / Days / CourseName):

The student will choose which category to search for, they may enter:

Professor

Your client should send this request to the main server via TCP connection. You are allowed to use any type of encoding. For example, you can use integer number 1 to represent EE and 0 to represent CS, or you can just use ascii EE and CS to represent the two departments. Similarly, you can use integer numbers to represent them. The main server will first extract the department information from the query and decide which department server has the corresponding information.

For the on-screen output, upon sending the request to the main server, your client should output an on-screen message. When receiving the information from the client, your main server should output an on-screen message. See the ON SCREEN MESSAGES table for details.

Phase 3B

In this part, your main server will send the query information to the backend department server via UDP connection. Your main server should output an on-screen message upon sending the request to the backend server. After getting the query information, the department server would look through its stored local information to obtain the corresponding course information.

If the course was founded, print out:

The course information has been founded: The <category> of <course code> is <information>

If not, print out:

Didn't find the course: <course code>.

See the ON SCREEN MESSAGES table for details.

Phase 4

Phase 4B

At the end of Phase 3, the responsible Department server should have the query information ready. The query information is first sent back to the Main server using UDP and print out an on-screen message.

Phase 4B

When the Main server receives the result, it needs to print out an on-screen message, forward the result to the Client using TCP and print out an on-screen message.
When the client receives the result, it will print out the query information and the prompt messages for a new request as follows:

The <category> of <course code> is <information>.

-----Start a new request----
Please enter the course code to query:

See the ON SCREEN MESSAGES table for details.

Extal Credits

If you want to earn 10 extra points, you can implement an extra functionality where a user can query N courses (N [ 10) at once and receive the corresponding information of all categories from different back-end servers respectively. To be more specific, the input format on the client side is:

<CourseCode1> <CourseCode2> <CourseCode3>......

Note: the maximum number of CourseCode is less than 10 and there is a whitespace between each CourseCode.

The request is sent to the main server using TCP. After receiving the packet, the main server will parse it and send one or two request(s) to the backend server(s). The one containing EE courses should be sent to the EE Department server, and the other containing CS courses should be sent to the CS Department server. The corresponding server will respond to the main server with all information of all categories. The main server will combine two responses from backend servers together and prepare one response message to the client. The final results shown at the client side should maintain the order of courses that the user input. For example, after the prompt shown on the client’s terminal:

Please enter the course code to query:

The client inputs the following CouseCodes:

EE450 EE669 CS402

The following table will be shown on the client’s terminal:

CourseCode: Credits, Professor, Days, Course Name
EE450: 4, Ali Zahid, Tue;Thu, Introduction to Computer Networks
EE669: 4, Jay Kuo, Mon;Wed, Multimedia Data Compression
CS402: 4, William Cheng, Mon;Wed, Operating Systems (Note: there is no need to print those vertical and horizontal lines in the above table)

NOTE: The extra points will be added to the full 100 points. The maximum possible points for this socket programming project is 110 points.

Process Flow/ Sequence of Operations:

Your project grader will start the servers in this sequence: serverM, serverC, serverEE, serverCS, Client in five different terminals.
Once all the ends are started, the servers and clients should be continuously running unless stopped manually by the grader or meet certain conditions as mentioned before.

Required Port Number Allocation

The ports to be used by the clients and the servers for the exercise are specified in the following table:
Note: Major points will be lost if the port allocation is not as per the below description.

Submission files and folder structure

Your submission should have the following folder structure and the files (the examples are of .cpp, but it can be .c files as well):

ee450_lastname_firstname_uscusername.tar.gz
- ee450_lastname_firstname_uscusername
  - client.cpp
  - serverM.cpp
  - serverC.cpp
  - serverCS.cpp
  - serverEE.cpp
  - Makefile
  - readme.txt (or) readme.md

The grader will extract the tar.gz file, and will place all the input data files in the same directory as your source files. The executable files should also be generated in the same directory as your source files. So, after testing your code, the folder structure should look something like this:

ee450_lastname_firstname_uscusername
- client.cpp
- serverM.cpp
- serverC.cpp
- serverCS.cpp
- serverEE.cpp
- Makefile
- readme.txt (or) readme.md
- client
- serverM
- serverC
- serverCS
- serverEE
- ee.txt
- cs.txt
- cred.txt

Note that in the above example, the input data files (ee.txt, cs.txt and cred.txt) will be manually placed by the grader, while the ‘make all’ command should generate the executable files.