B97 : Project.04 Networking and Network Programming using Sockets, TCP/IP, IPv4, IPv6

sankalpnegi2310

Post about ur work done and doubts.

kuldeep_ecb

Socket Programming AF_UNIX

Server.c

Step1: Create Socket:- socket(AF_UNIX, SOCK_STREAM, 0);

Step2: Naming Socket :-

my_addr.sun_family = AF_UNIX; //Define Domain

strncpy(my_addr.sun_path, "my_socket",10); // Giving name here of socket

bind(sfd, (struct sockaddr *) &my_addr,sizeof(struct sockaddr_un)) //bind

Step3: Create Listen Queue

listen(sfd, 1) ;// create no of listen queues ex : 1 here we can put 2,3 ...50

Step4: Get new file descriptors for individual requests from clients

addr_size = sizeof(struct sockaddr_un);

cfd = accept(sfd, (struct sockaddr *) &my_addr,&addr_size); // It will be on block mode while client will not send connect request on this socket

Now you can use write or read using this file descriptor

Ex:-write(cfd,"server ",6);

Client.c

Step1:- Create Socket:- socket(AF_UNIX, SOCK_STREAM, 0);

Step2:- Connect it with the same name of Socket

peer_addr.sun_family = AF_UNIX;//Define Domain

strncpy(peer_addr.sun_path, "my_socket",10); // Giving name here of socket

peer_addr_size = sizeof(struct sockaddr_un);

ret = connect(sfd, (struct sockaddr *) &peer_addr, peer_addr_size);// It will not return file descriptor it returns only pass fail.

After Success we can read from file descriptor

read(sfd,&buf,20);

Note:-

So In server there are 2 or more file descriptors. one when socket created and other when accept call.

So we will use 2nd,3rd.... file descriptors which are related to client connect requests.

But in client.c we use 1 file descriptor which socket call gives first time. because connect doesn't return file descriptors.

kuldeep_ecb

Firewall Error While making any system as Server

Problem:- My system was successfully responding to another system as a client but it was not able to serve as a Server. Reason was Firewall.

Solution:-

systemctl stop firewalld.service

kuldeep_ecb

Socket Programming AF_INET

Server.c

Here we will use structure struct sockaddr_in my_addr

Step1: Create Socket:- socket(AF_INET, SOCK_STREAM, 0);

Step2: Naming Socket :-

my_addr.sin_family = AF_INET;

my_addr.sin_addr.s_addr = htonl(INADDR_ANY);// for accept any client host to network large

my_addr.sin_port = htons(9090);// host to network small

bind(sfd, (struct sockaddr *) &my_addr,sizeof(struct sockaddr_in)) //bind

Step3: Create Listen Queue

listen(sfd, 1) ;// create no of listen queues ex : 1 here we can put 2,3 ...50

Step4: Get new file descriptors for individual requests from clients

addr_size = sizeof(struct sockaddr_in);

cfd = accept(sfd, (struct sockaddr *) &client_addr,&addr_size); // It will be on block mode while client will not send connect request on this socket

Now you can use write or read using this file descriptor

Ex:-write(cfd,"server ",6);

Client.c

Step1:- Create Socket:- socket(AF_INET, SOCK_STREAM, 0);

Step2:- Connect it with the same name of Socket

peer_addr.sin_family = AF_INET;

peer_addr.sin_port = htons(port_no);// for little endian and Big endian conversion host to network small

peer_addr..sin_addr.s_addr = inet_addr("192.168.IP address");

ret = connect(sfd, (struct sockaddr *) &peer_addr, peer_addr_size);

after Success we can read from file descriptor

read(sfd,&buf,20);

kuldeep_ecb

Thread Based Project on Socket for handling Multiple Clients

Step1: Create a new thread from main.

Step2: In this thread implement accept on block in infinite loop to handle back to back requests.

Step3: In this while loop creates a new thread to calculation/ request Processing.

Step4: Create reuquest from clients and give response from Server.

Here I have implemented detachable threads while creating thread for request Processing in Step3. Earlier when I was using joinable that was creating problem like it was not running smoothly because that Step3 parent thread was waiting for finishing child threads so thats why there I observed some delay. To avoid this I created detachable threads, Now it is running smoothly.

I was also getting some error Too many files are opened but now I have resolved this .

I have checked this between two Computers over a network

Some useful commands:-

ifconfig :- to show your( Server ) IP address.

netstat -ntlp :- Active Internet connections (only servers)

Firewall Error system as Server

Problem:- My system was successfully responding to another system as a client but it was not able to serve as a Server. Reason was Firewall.

Solution:-

systemctl stop firewalld.service

vishwajeet.gaur1989

Re-Binding the same listening port multiple times

As we all know the unlink() trick only works on AF_UNIX sockets of the sort which appear as actual files in the filesystem...

For AF_INET sockets, there is no filesystem token representing them; only a list of bound ports/IPs kept track of by the kernel...

For all TCP servers, it's common and recommended to also setsockopt(SO_REUSEADDR), which will allow a recently terminated and active server to re-bind the same listening port, even if there are lingering TIME_WAIT sockets on that port#... So, that will probably solve the problem here...

So, just set SO_REUSEADDR, and all should be well... <just before you bind(), do:>

Syntax::

int on = 1; setsockopt (sd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof (on));

where, sd stands for Socket Fd.

B97 : Project.04 Networking and Network Programming using Sockets, TCP/IP, IPv4, IPv6

Howdy, Stranger!

Categories