CNS 3rd practical socket programming in c and c++ only

 

What is socket programming?

Socket programming is a way of connecting two nodes on a network to communicate with each other. One socket(node) listens on a particular port at an IP, while the other socket reaches out to the other to form a connection. The server forms the listener socket while the client reaches out to the server.

Server.c

• C

// Server side C/C++ program to demonstrate Socket // programming #include <netinet/in.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/socket.h> #include <unistd.h> #define PORT 8080 int main(int argc, char const* argv[]) {     int server_fd, new_socket, valread;     struct sockaddr_in address;     int opt = 1;     int addrlen = sizeof(address);     char buffer[1024] = { 0 };     char* hello = "Hello from server";        // Creating socket file descriptor     if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {         perror("socket failed");         exit(EXIT_FAILURE);     }        // Forcefully attaching socket to the port 8080     if (setsockopt(server_fd, SOL_SOCKET,                    SO_REUSEADDR | SO_REUSEPORT, &opt,                    sizeof(opt))) {         perror("setsockopt");         exit(EXIT_FAILURE);     }     address.sin_family = AF_INET;     address.sin_addr.s_addr = INADDR_ANY;     address.sin_port = htons(PORT);        // Forcefully attaching socket to the port 8080     if (bind(server_fd, (struct sockaddr*)&address,              sizeof(address))         < 0) {         perror("bind failed");         exit(EXIT_FAILURE);     }     if (listen(server_fd, 3) < 0) {         perror("listen");         exit(EXIT_FAILURE);     }     if ((new_socket          = accept(server_fd, (struct sockaddr*)&address,                   (socklen_t*)&addrlen))         < 0) {         perror("accept");         exit(EXIT_FAILURE);     }     valread = read(new_socket, buffer, 1024);     printf("%s\n", buffer);     send(new_socket, hello, strlen(hello), 0);     printf("Hello message sent\n");        // closing the connected socket     close(new_socket);     // closing the listening socket     shutdown(server_fd, SHUT_RDWR);     return 0; }

client.c

• C

// Client side C/C++ program to demonstrate Socket // programming #include <arpa/inet.h> #include <stdio.h> #include <string.h> #include <sys/socket.h> #include <unistd.h> #define PORT 8080    int main(int argc, char const* argv[]) {     int status, valread, client_fd;     struct sockaddr_in serv_addr;     char* hello = "Hello from client";     char buffer[1024] = { 0 };     if ((client_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {         printf("\n Socket creation error \n");         return -1;     }        serv_addr.sin_family = AF_INET;     serv_addr.sin_port = htons(PORT);        // Convert IPv4 and IPv6 addresses from text to binary     // form     if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)         <= 0) {         printf(             "\nInvalid address/ Address not supported \n");         return -1;     }        if ((status          = connect(client_fd, (struct sockaddr*)&serv_addr,                    sizeof(serv_addr)))         < 0) {         printf("\nConnection Failed \n");         return -1;     }     send(client_fd, hello, strlen(hello), 0);     printf("Hello message sent\n");     valread = read(client_fd, buffer, 1024);     printf("%s\n", buffer);        // closing the connected socket     close(client_fd);     return 0; }

Compiling:

gcc client.c -o client
gcc server.c -o server

Output:

Client:Hello message sent
Hello from server
Server:Hello from client
Hello message sent

More clearly on youtube also available

Socket Programming - Tutorial Series Overview - YouTube