Linux C server and client simple communication

Server.c

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

int main (int argc, char *argv[])
{
int sockfd,new_fd;
struct sockaddr_in server_addr;
struct sockaddr_in client_addr;
int sin_size,portnumber;
Char hello[1000]= "hello! Is you fine?\n ";

if (argc!=2)
{
fprintf (stderr, "usage:%s portnumber\a\n", argv[0]);
Exit (1);
}

if ((Portnumber=atoi (argv[1))) <0)
{
fprintf (stderr, "usage:%s portnumber\a\n", argv[0]);
Exit (1);
}

/* Start building the socket descriptor on server side */
if ((Sockfd=socket (af_inet,sock_stream,0)) ==-1)
{
fprintf (stderr, "Socket error:%s\n\a", Strerror (errno));
Exit (1);
}

/* Server-side populated sockaddr structure */
Bzero (&server_addr,sizeof (struct sockaddr_in));
Server_addr.sin_family=af_inet;
Server_addr.sin_addr.s_addr=htonl (Inaddr_any);
Server_addr.sin_port=htons (PortNumber);

/* Bundle SOCKFD Descriptor */
if (bind (SOCKFD, struct sockaddr *) (&AMP;SERVER_ADDR), sizeof (struct sockaddr)) ==-1)
{
fprintf (stderr, "Bind error:%s\n\a", Strerror (errno));
Exit (1);
}

/* Listen for SOCKFD descriptors */
if (Listen (sockfd,5) ==-1)
{
fprintf (stderr, "Listen error:%s\n\a", Strerror (errno));
Exit (1);
}

while (1)
{
/* Server blocked until client program establishes a connection */
sin_size=sizeof (struct sockaddr_in);
if ((New_fd=accept (SOCKFD, (struct sockaddr *) (&AMP;CLIENT_ADDR), &sin_size)) ==-1)
{
fprintf (stderr, "Accept error:%s\n\a", Strerror (errno));
Exit (1);
}

fprintf (stderr, "Server get connection from%s\n",
Inet_ntoa (CLIENT_ADDR.SIN_ADDR));

FSCANF (stdin, "%s", hello);
if (Write (New_fd,hello,strlen (hello)) ==-1)
{
fprintf (stderr, "Write error:%s\n", Strerror (errno));
Exit (1);
}
/* This communication is over */
Close (NEW_FD);
/* Cycle the next one */
}
Close (SOCKFD);
Exit (0);
}

Client.c

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

int main (int argc, char *argv[])
{
int sockfd;
Char buffer[1024];
struct sockaddr_in server_addr;
struct Hostent *host;
int portnumber,nbytes;

if (argc!=3)
{
fprintf (stderr, "usage:%s hostname portnumber\a\n", argv[0]);
Exit (1);
}

if ((Host=gethostbyname (argv[1))) ==null)
{
fprintf (stderr, "GetHostName error\n");
Exit (1);
}

if ((Portnumber=atoi (argv[2))) <0)
{
fprintf (stderr, "usage:%s hostname portnumber\a\n", argv[0]);
Exit (1);
}

/* Client starts to build SOCKFD descriptor */
if ((Sockfd=socket (af_inet,sock_stream,0)) ==-1)
{
fprintf (stderr, "Socket error:%s\a\n", Strerror (errno));
Exit (1);
}

/* Client program fills the data on the server */
Bzero (&server_addr,sizeof (SERVER_ADDR));
Server_addr.sin_family=af_inet;
Server_addr.sin_port=htons (PortNumber);
server_addr.sin_addr=* (struct in_addr *) host->h_addr);

/* Client Initiates connection request */
if (Connect (SOCKFD, (struct sockaddr *) (&AMP;SERVER_ADDR), sizeof (struct sockaddr)) ==-1)
{
fprintf (stderr, "Connect error:%s\a\n", Strerror (errno));
Exit (1);
}

/* Connection succeeded */
if ((Nbytes=read (sockfd,buffer,1024)) ==-1)
{
fprintf (stderr, "Read error:%s\n", Strerror (errno));
Exit (1);
}
buffer[nbytes]= ' + ';
printf ("I have received:%s\n", buffer);
/* End Communication */
Close (SOCKFD);
Exit (0);
}

Makefile

All:server Client
Server:server.c
GCC $^-o [email protected]
Client:client.c
GCC $^-o [email protected]

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Linux C server and client simple communication