Networks Project Details

Five measures of a protocol

1. What layer is my protocol going to sit at / on top of
2. What services does it provide
3. design the header

Part 1 of Project

• Explain in a word doc all your plans for the project, what protocol you will use,
• about 10 days

Part 2 of Project

• Have until August to complete the programming of the project. 16-18 days
• No GUI required, can just use the linux terminal or windows PowerShell.y

Socket Programming

• Socket is the API to access transport layer
• has a ip number port concatenation
  • Ex. 192.168.5.4:1234
• (local ip, local port, foreign IP, foreign port)
• TCP uses Stream socket interface, UDP uses datagram socket interface
• How to use socket
  1. Setup socket
     1. Where is the remote machine
     2. What service gets the data (port)
     • Both client and server need to setup a socket
       • Windows WSL (Windows Socket Library)
     • Client setup
       • AF_INET is the IP domain
       • Type - SOCK_STREAM to use TCP
       • Protocol - 0
       • EX. int socket = (AF_INET, SOCK_STREAM, 0)
     • Server setup
       • port number > 49152 for private ports
  2. send and receive
     1. send — write
     2. recv — read
  3. close the socket
• Use threads to avoid the blocking problem
• two threads on each end, both having an infinite while loop. They wait and loop until either you send or receive a message. When you type “quit” the loop hits a break; statement to exit the loop
• There is an ip call to get my current ip address
• loop around address 127.0.0.1

API Calls

• Blocking API Calls
  • the program does not continue until the API is resolved
  • system.in or cin stops the program until the user inputs something on the keyboard
  • sleep is always a blocking call and can be used after a non-blocking API call to force the function to block so that other functions or processes can work while we wait for input
• Non-Blocking API calls
  • non blocking API calls will continue regardless if the function is answered