LU7 Socket Programming Flashcards by Music Sanitizer

What is the primary purpose of socket programming?

To enable IPC, especially across a network in a distributed system

How well did you know this?

Not at all

Perfectly

In a networked environment, what architectural model is commonly used with sockets?

Client-server model

How well did you know this?

Not at all

Perfectly

Briefly describe the role of the ‘client’ in a client-server socket communication.

Initiates a connection to the server and requests services.

How well did you know this?

Not at all

Perfectly

Describe the role of the ‘server’ in the client-server model.

Listens for incoming connections, accepts requests, and provides services.

How well did you know this?

Not at all

Perfectly

What’s the purpose of fork()?

Creating child process.

How well did you know this?

Not at all

Perfectly

How do processes communicate between parent and child after a fork()?

[ SPMs ]

Using IPC mechanisms:

signal
pipes
message queues
shared memory

How well did you know this?

Not at all

Perfectly

In a networked program using sockets, what medium enables communication between client and server?

A network (e.g., LAN, WAN).

How well did you know this?

Not at all

Perfectly

What defines the rules for communication between sockets?

Protocols (e.g., TCP/IP).

How well did you know this?

Not at all

Perfectly

What are sockets?

The traditional UNIX IPC mechanism that allows processes to communicate, even if they’re on different machines.

How well did you know this?

Not at all

Perfectly

Name a few common uses of sockets?

transferring data/video/voice/files from one machine to another

How well did you know this?

Not at all

Perfectly

Name two types of connections.

Connection-oriented, Connectionless

Connection-oriented communication (like TCP) establishes a dedicated, reliable connection with ordered delivery.
Connectionless communication (like UDP) sends data independently without guarantees of order or delivery.

How well did you know this?

Not at all

Perfectly

What are the key characteristics of Connection oriented model?

dedicated connection
reliable packet transfer
packet will send and receive in order

How well did you know this?

Not at all

Perfectly

What are the key characteristics of Connectionless oriented model?

Data packets routed individually
No guarantee of delivery, order, or data integrity, speed prioritized

How well did you know this?

Not at all

Perfectly

Name a common protocol used for connection oriented model.

TCP/IP
Transmission Control Protocol/Internet Protocol

How well did you know this?

Not at all

Perfectly

Name a common protocol used for connectionless oriented model.

UDP
user datagram protocol

How well did you know this?

Not at all

Perfectly

What is the disadvantage of Connection oriented model?

Requires more overhead due to the setup phase, slower compared to connectionless model

How well did you know this?

Not at all

Perfectly

What is the disadvantage of Connectionless oriented model?

Data packets may arrive out of order or be lost, less reliable than connection-oriented communication.

How well did you know this?

Not at all

Perfectly

To establish any communication, client and server need to be connected at what level?

Hardware & Software level

How well did you know this?

Not at all

Perfectly

What are the few steps in a server?

[ CNSAS ]

creating a server socket
naming a server socket
set the maximum number of pending connections
accepting connections
serving a client

How well did you know this?

Not at all

Perfectly

What are the few steps in a client?

1 creating a client socket
2. connecting a client socket to the server socket
3. communicating via sockets

How well did you know this?

Not at all

Perfectly

What is the format of IP address?

4 decimal numbers separated by dot

How well did you know this?

Not at all

Perfectly

How UNIX system calls deal with IP address to be usable for later?

convert using inet_addr()

How well did you know this?

Not at all

Perfectly

What is a socket?

An interface between application and network

How well did you know this?

Not at all

Perfectly

What does the socket type dictates?

style of communication (reliable or best effort, connection-oriented or connectionless)

How well did you know this?

Not at all

Perfectly

What are the two essential types of sockets?

* SOCK_STREAM: connection-oriented * SOCK_DGRAM: connectionless

SOCK_STREAM is also known as?

TCP

SOCK_DGRAM is also known as?

UDP

What is the characteristic of a SOCK_STREAM?

reliable delivery, in-order guaranteed, connection-oriented, bidirectional

What is the characteristic of a SOCK_DGRAM?

unreliable delivery, no order guarantees, no notion of “connection

What library does the socket address structure define in?

sys/socket.h

In socket, what are the address and port for?

* `address` = knowing which machine to communicate with * `port` = which channel/app to connect

What does the server do with the port?

Server listens for connection on a specified port number

How many ports does each host has?

65,536 (2^16)

What's the function of socket() system call?

To create a **comunication end point** (a socket) within a network

What are the parameters for socket()?

domain, int type, int protocol

What is network type `AF_INET` for?

AF = Address family INET = Internet internet domain

What is network type`AF_UNIX` for?

AF = Address Family within the same machine (local) Provide a way for programs running on the **same** computer (local) to communicate with each other.

What does SOCK_STREAM dictates?

for connection oriented

What does SOCK_DGRAM dictates?

for connectionless oriented

If SOCK_STREAM used, which protocol will it use?

TCP

If SOCK_DGRAM used, which protocol will it use?

UDP

What is bind() function used for?

It **associates** a socket with an IP and port, enabling the OS to **route** network traffic to the correct server application.

What are the parameters for bind()?

* `sockfd` * `struct sockaddr *address` * `size_t add_len`

What is listen() function used for?

Setup server to wait for connection

What are the parameters for listen()?

* `sockfd` * `int queue_size`

What does queue_size in listen() do?

set the *maximum* number of *pending connection* from the client.

What is accept() function used for?

When received connection request from client, server need to create a new second socket to handle the communication

What are the parameters for accept()?

sockfd, struct sockaddr *address, size_t *add_len

Why is add_len can be NULL in accept()

Due to the nature of connection oriented model, can be set to NULL

In order to request for a connection, what function do we need to use?

connect()

What are the parameters for connect()

csockfd, const struct sockaddr *address, size_t add_len

How do send and receive data between client and server?

recv(), send()

What are the parameters for recv()?

sockfd, void *buffer, size_t length, int flags

What are the parameters for send()?

sockfd, const void *buffer, size_t length, int flags

What does MSG_PEEK do?

look at data without actually receiving

What does MSG_OOB do?

receive out of band data like interrupt signal

When does MSG_WAITALL return?

return only when full amount of data is available

What does flags for sending MSG_OOB do?

send out of band data

What does flags for sending MSG_DONTROUTE do?

message is send via most direct route rather than quickest route

How to close the connection?

close(int sockfd)

If the type is SOCK_STREAM, what does close() do?

kernel will guarantee that all data sent to the socket will be sent to the receiving process and close() to be blocked until completion

If the type is SOCK_DGRAM, what does close() do?

Socket is closed immediately

If Inet_Addr fail, what will it return?

-1

When the type is SOCK_STREAM, which operations will occur on the server?

Socket->bind->listen->accept->read->write->close

When the type is SOCK_STREAM, which operations will occur on the **client**?

Socket->connect->send->recv->close

TCP is which of these choice, 1. Reliable 2. Unreliable 3. Connectionless 4. Connection-Oriented, Pick two?

Reliable and Connection-Oriented

UDP is which of these choice, 1. Reliable 2. Unreliable 3. Connectionless 4. Connection-Oriented, Pick two?

Unreliable and Connectionless

What happens if client doesn't close socket?

There is no defined outcome

Does client or server always closes first?

Either can close first

What is the purpose of the 'domain' argument in the `socket()` function, and what is the most common value used for internet-based communication?

Specifies the communication domain; AF_INET is the most common for internet.

Explain the key difference between TCP and UDP in terms of data delivery.

TCP guarantees reliable, ordered delivery; UDP does not.

What is the purpose of setting a maximum number of pending connections using the `listen()` function?

Limits the number of incoming connection requests the server will queue.

What information is filled into the `sockaddr` structure when the `accept()` function returns a new socket descriptor?

Client's address and port information.

Imagine you're using a 'SOCK_STREAM' socket to send data over a network connection. You call the `close()` function to close the socket. Why might this `close()` call take some time to finish, instead of returning immediately?

Because the kernel needs to ensure that all data is sent to the receiving process.

Why is network address conversion necessary when using UNIX networking system calls?

UNIX system calls can't directly use standard IP address format.

What is the purpose of `inet_addr()`?

Converts human-readable IP address to a numeric form.

What data type does `inet_addr()` return on success?

in_addr_t

What are the typical return values of the function accept()?

New socket identifier

In the context of networking, what is a 'port'?

A channel or endpoint used for communication between processes.

What is the valid range for port numbers, and which range is reserved for specific applications?

0-65535, 0-1023 are reserved.

Name a scenario where TCP (SOCK_STREAM) is preferable over UDP (SOCK_DGRAM).

When complete and accurate data transmission is critical (e.g., file transfer).

Explain the significance of the `sa_family` field within the `sockaddr` structure.

Specifies the address family (e.g., AF_INET for IPv4).

What are the arguments to socket function in the context of creating a TCP socket?

domain=AF_INET, type=SOCK_STREAM, protocol=0

What are the arguments to socket function in the context of creating a UDP socket?

domain=AF_INET, type=SOCK_DGRAM, protocol=0

True or False: A single server can handle only one client connection at a time.

False

True or False: UDP guarantees that packets will arrive in the order they were sent.

False

In a client-server interaction with sockets, what does it signify if connect() return -1?

Failed

What is the purpose of calling listen() on server side?

Sets up the queue for upcoming connection requests

If a server creates a socket for handling HTTP traffic, what port number would it commonly use?

When designing the server what happens after accepting

Need to create a new second socket to handle the connection

Is it possible for the client to know what is going to send

Yes

In connection oriented, what does it mean when connection has been achieved?

A stable connection is made and you can start communication!

When to close the connection?

After all the data has been transferred. It is advised to close the connection ASAP!

Does TCP perform Error Check?

Yes

What is the downside of UDP other than unreliable data?

No congestion control

What operations is the client side required to have if it wishes to connect to the server?

Socket and connect function calls are required