Chat Server (Network Programming in C) - c

Question

I have made the following chat server program in c. The Problem is that as soon as I run my client and 'Client Says :-' is displayed on the Client Screen, the server immediately displays 'Client Says :-', 'Server Says :-' without waiting for the Client to give the input and then process it and the program doesnot work after that no matter what I input.
I want my Client to ask for input then send it to server , The server should then display the Client's input and ask for it's own input. This should go on until anyone of them enters 'bye'.
//Chat Server
#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<string.h>
#include<errno.h>
int main()
{
int sockfd = socket(AF_INET,SOCK_STREAM,0);
if(sockfd<0)
{
perror("Error in Creating Socket\n");
exit(-1);
}
struct sockaddr_in server,client;
bzero(&server,sizeof(server));
server.sin_family = AF_INET;
server.sin_port = htons(10000);
server.sin_addr.s_addr = INADDR_ANY;
if(bind(sockfd, (struct sockaddr*)&server, sizeof(server))<0)
{
perror("Error in Socket Binding\n");
exit(-1);
}
if(listen(sockfd,5)<0)
{
perror("Error in Listening\n");
exit(-1);
}
printf("Listening\n");
char clientsent[500];
char bhago[5] = "exit";
bhago[5] = '\0';
char serverinput[500];
while(1)
{
int acceptfd = accept(sockfd, (struct sockaddr*)&client, (socklen_t*)sizeof(client));
pid_t pid = fork();
if(pid == 0)//child process is executing
{
close(sockfd);
while(1)
{
bzero(&serverinput, 500);
bzero(&clientsent, 500);
int n = recv(acceptfd, clientsent,500,0);
printf("Client Says :-\n");
printf("%s",clientsent);
if(strcmp(clientsent,bhago) == 0)
{
close(acceptfd);
exit(0);
}
printf("Server Says :-\n");
int x = 0;
do{
serverinput[x]=getchar();
x++;
}while(x-1 != '\n');
send(acceptfd, serverinput, 500, 0);
if(strcmp(serverinput,bhago) == 0)
{
close(acceptfd);
exit(0);
}
}
}
close(acceptfd);
}
}
//Chat Client
#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<string.h>
#include<errno.h>
int main()
{
int sockfd = socket(AF_INET,SOCK_STREAM,0);
if(sockfd<0)
{
perror("Error in Creating Socket\n");
exit(-1);
}
struct sockaddr_in server;
bzero(&server,sizeof(server));
server.sin_family = AF_INET;
server.sin_port = htons(10000);
server.sin_addr.s_addr = INADDR_ANY;
if(connect(sockfd, (struct sockaddr*)&server, sizeof(server))<0)
{
perror("Error in Connection\n");
exit(-1);
}
printf("Connection Established\n");
char clientinput[500];
char bhago[5] = "exit";
bhago[5] = '\0';
char serversent[500];
while(1)
{
bzero(&clientinput, 500);
bzero(&serversent, 500);
printf("Client Says :-\n");
int x = 0;
do{
clientinput[x]=getchar();
x++;
}while(x-1 != '\n');
send(sockfd, clientinput, 500, 0);
if(strcmp(clientinput, bhago) == 0)
{
close(sockfd);
exit(0);
}
printf("Server Said :-\n");
recv(sockfd, serversent, 500,0);
printf("%s",serversent);
if(strcmp(serversent, bhago) == 0)
{
close(sockfd);
exit(0);
}
}
close(sockfd);
}//main

Answer 1

For starters, the latter of those two lines
char bhago[5] = "exit";
bhago[5] = '\0';
invokes undefined behaviour by writing out of bhago's bounds by accessing the 6th element, with bhago being 5 elements wide. From now on anything can happen.
In C arrays' indexes are 0-based. The 1st element here is bhago[0].
And this
..., (socklen_t*)sizeof(client));
is plain horrible wrong. Do not blindly cast away compilation errors. A pointer is expected and the code passes a compile-time constant, invoking undefined behaviour again here. I'd expect the code to die with execution of this line immediately.
accept() expects a socklen_t * as last parameter, so pass one:
socklen_t socklen = sizeof client;
..., &socklen));