tcp_full_duplex_client.c File Reference

Client-side implementation of TCP Full Duplex Communication More...

#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

Include dependency graph for tcp_full_duplex_client.c:

Macros
#define	PORT   10000
	For the type in_addr_t and in_port_t For structures returned by the network database library - formatted internet addresses and port numbers For in_addr and sockaddr_in structures. More...

Functions
void	error ()
	Utility function used to print an error message to stderr. More...
int	main ()
	Main function. More...

Detailed Description

Client-side implementation of TCP Full Duplex Communication

Author

NVombat

See also

tcp_full_duplex_server.c

The algorithm is based on the simple TCP client and server model. However, instead of the server only sending and the client only receiving data, The server and client can both send and receive data simultaneously. This is implemented by using the fork function call so that in the server the child process can receive data and parent process can send data, and in the client the child process can send data and the parent process can receive data. It runs an infinite loop and can send and receive messages indefinitely until the user exits the loop. In this way, the Full Duplex Form of communication can be represented using the TCP server-client model & socket programming

Macro Definition Documentation

PORT

#define PORT   10000

For the type in_addr_t and in_port_t For structures returned by the network database library - formatted internet addresses and port numbers For in_addr and sockaddr_in structures.

For specific bit size values of variables Variable types, several macros, and various functions for performing input and output Variable types, several macros, and various functions for performing general functions Various functions for manipulating arrays of characters For macro definitions related to the creation of sockets For definitions to allow for the porting of BSD programs For miscellaneous symbolic constants and types, and miscellaneous functions

Function Documentation

error()

void error

(

)

Utility function used to print an error message to stderr.

It prints str and an implementation-defined error message corresponding to the global variable errno.

Returns

void

{
    perror("Socket Creation Failed");
    exit(EXIT_FAILURE);
}

main()

int main

(

void

)

Main function.

Returns

0 on exit

Variable Declarations

< socket descriptors - Like file handles but for sockets

< character arrays to read and store string data for communication

< basic structures for all syscalls and functions that deal with internet addresses. Structures for handling internet addresses

The TCP socket is created using the socket function.

AF_INET (Family) - it is an address family that is used to designate the type of addresses that your socket can communicate with

SOCK_STREAM (Type) - Indicates TCP Connection - A stream socket provides for the bidirectional, reliable, sequenced, and unduplicated flow of data without record boundaries. Aside from the bidirectionality of data flow, a pair of connected stream sockets provides an interface nearly identical to pipes.

0 (Protocol) - Specifies a particular protocol to be used with the socket. Specifying a protocol of 0 causes socket() to use an unspecified default protocol appropriate for the requested socket type.

Server Address Information

The bzero() function erases the data in the n bytes of the memory starting at the location pointed to, by writing zeros (bytes containing '\0') to that area.

We bind the server_addr to the internet address and port number thus giving our socket an identity with an address and port where it can listen for connections

htons - The htons() function translates a short integer from host byte order to network byte order

htonl - The htonl() function translates a long integer from host byte order to network byte order

These functions are necessary so that the binding of address and port takes place with data in the correct format

Connects the client to the server address using the socket descriptor This enables the two to communicate and exchange data

Communication between client and server

The bzero() function erases the data in the n bytes of the memory starting at the location pointed to, by writing zeros (bytes containing '\0') to that area. The variables are emptied and then ready for use

The fork function call is used to create a child and parent process which run and execute code simultaneously

The child process is used to send data and after doing so sleeps for 5 seconds to wait for the parent to receive data

The parent process is used to receive data and after doing so sleeps for 5 seconds to wait for the child to send data

The server and client can communicate indefinitely till one of them exits the connection

Since the exchange of information between the server and client takes place simultaneously this represents FULL DUPLEX COMMUNICATION

Value of 0 is for child process

Parent Process

Close Socket

{
    /** Variable Declarations */
    uint32_t
        sockfd;  ///< socket descriptors - Like file handles but for sockets
    char sendbuff[1024],
        recvbuff[1024];  ///< character arrays to read and store string data
                         /// for communication
 
    struct sockaddr_in
        server_addr;  ///< basic structures for all syscalls and functions that
                      /// deal with internet addresses. Structures for handling
                      /// internet addresses
 
    /**
     * The TCP socket is created using the socket function.
     *
     * AF_INET (Family) - it is an address family that is used to designate the
     * type of addresses that your socket can communicate with
     *
     * SOCK_STREAM (Type) - Indicates TCP Connection - A stream socket provides
     * for the bidirectional, reliable, sequenced, and unduplicated flow of data
     * without record boundaries. Aside from the bidirectionality of data flow,
     * a pair of connected stream sockets provides an interface nearly identical
     * to pipes.
     *
     * 0 (Protocol) - Specifies a particular protocol to be used with the
     * socket. Specifying a protocol of 0 causes socket() to use an unspecified
     * default protocol appropriate for the requested socket type.
     */
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        error();
    }
 
    /**
     * Server Address Information
     *
     * The bzero() function erases the data in the n bytes of the memory
     * starting at the location pointed to, by writing zeros (bytes
     * containing '\0') to that area.
     *
     * We bind the server_addr to the internet address and port number thus
     * giving our socket an identity with an address and port where it can
     * listen for connections
     *
     * htons - The htons() function translates a short integer from host byte
     * order to network byte order
     *
     * htonl - The htonl() function translates a long integer from host byte
     * order to network byte order
     *
     * These functions are necessary so that the binding of address and port
     * takes place with data in the correct format
     */
    bzero(&server_addr, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
 
    printf("Client is running...\n");
 
    /**
     * Connects the client to the server address using the socket descriptor
     * This enables the two to communicate and exchange data
     */
    connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
 
    printf("Client is connected...\n");
 
    /**
     * Communication between client and server
     *
     * The bzero() function erases the data in the n bytes of the memory
     * starting at the location pointed to, by writing zeros (bytes
     * containing '\0') to that area. The variables are emptied and then
     * ready for use
     *
     * The fork function call is used to create a child and parent process
     * which run and execute code simultaneously
     *
     * The child process is used to send data and after doing so
     * sleeps for 5 seconds to wait for the parent to receive data
     *
     * The parent process is used to receive data and after doing so
     * sleeps for 5 seconds to wait for the child to send data
     *
     * The server and client can communicate indefinitely till one of them
     * exits the connection
     *
     * Since the exchange of information between the server and client takes
     * place simultaneously this represents FULL DUPLEX COMMUNICATION
     */
    pid_t pid;
    pid = fork();
    if (pid == 0)  /// Value of 0 is for child process
    {
        while (1)
        {
            bzero(&sendbuff, sizeof(sendbuff));
            printf("\nType message here: ");
            fgets(sendbuff, 1024, stdin);
            send(sockfd, sendbuff, strlen(sendbuff) + 1, 0);
            printf("\nMessage sent!\n");
            sleep(5);
            // break;
        }
    }
    else  /// Parent Process
    {
        while (1)
        {
            bzero(&recvbuff, sizeof(recvbuff));
            recv(sockfd, recvbuff, sizeof(recvbuff), 0);
            printf("\nSERVER: %s\n", recvbuff);
            sleep(5);
            // break;
        }
    }
 
    /// Close Socket
    close(sockfd);
    printf("Client is offline...\n");
    return 0;
}

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