GATE CSE 2015 Set 2 | Question: 20

Question

Identify the correct order in which a server process must invoke the function calls accept, bind, listen, and recv according to UNIX socket API.

• A. $\textsf{listen, accept, bind, recv}$
• B. $\textsf{bind, listen, accept, recv}$
• C. $\textsf{bind, accept, listen, recv}$
• D. $\textsf{accept, listen, bind, recv}$

Comments

References : 1) http://soft.vub.ac.be/~tvcutsem/distsys/sockets.pdf

                     2) http://www.csd.uoc.gr/~hy556/material/tutorials/cs556-3rd-tutorial.pdf

Answer 1

Answer: (B)

$\textsf{Bind:}$ Binds the socket to an address

$\textsf{Listen:}$ Waits for connections to the socket

$\textsf{Accept:}$ Accepts a connection to the socket 

$\textsf{Recv:}$ Receives data from connection

From Man page of accept:

It extracts the first connection request on the queue of pending connections for the listening socket, creates a  new connected socket,  and returns a new file descriptor referring to that socket.  The newly created socket is not in the listening state. The original socket is unaffected by this call.

Comments

Yes.

Read this link

http://www.cs.dartmouth.edu/~campbell/cs60/socketprogramming.html

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@bad doctor

This topic is still in syllabus of GATE 2021.

Source: https://gatecse.in/gate-2021-syllabus-including-changes/

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Vikrant+Singh

Thanks :)

Answer 2

recv function same  as read()

Answer 3

correct order in which a server process must invoke the function calls accept, bind, listen, and recv according to UNIX socket API will be

bind ->listen -> accept -> recv

First three function call will be used to connection establishment and recv function call is used to transfer data after successful connection establishment.

Answer 4

The sequence goes like this:-

1. socket() or socket_init() — creates the socket.
   
    
2. bind() — binds the local machine's IP address and port number to the socket.
   
    
3. connect() — sends SYN packets (Client's perspective)

   ---

   listen() — waits for someone to send SYN packets (Server's perspective)
   accept() — sends ACK in response to SYN (Server's perspective)
   
    
4. send() — sends data.

   recv() — receives data.
   
    

5. close() — sends FIN packets to close the connection.

 

Option B