multiuser chat server in c

Multi user chat server using TCP as transport layer protocol

server.c ( server program )

#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <pthread.h>

pthread_mutex_t mutex;
int clients[20];
int n=0;

void sendtoall(char *msg,int curr){
	int i;
	pthread_mutex_lock(&mutex);
	for(i = 0; i < n; i++) {
		if(clients[i] != curr) {
			if(send(clients[i],msg,strlen(msg),0) < 0) {
				printf("sending failure n");
				continue;
			}
		}
	}
	pthread_mutex_unlock(&mutex);
}

void *recvmg(void *client_sock){
	int sock = *((int *)client_sock);
	char msg[500];
	int len;
	while((len = recv(sock,msg,500,0)) > 0) {
		msg[len] = '';
		sendtoall(msg,sock);
	}
	
}

int main(){
	struct sockaddr_in ServerIp;
	pthread_t recvt;
	int sock=0 , Client_sock=0;
	
	ServerIp.sin_family = AF_INET;
	ServerIp.sin_port = htons(1234);
	ServerIp.sin_addr.s_addr = inet_addr("127.0.0.1");
	sock = socket( AF_INET , SOCK_STREAM, 0 );
	if( bind( sock, (struct sockaddr *)&ServerIp, sizeof(ServerIp)) == -1 )
		printf("cannot bind, error!! n");
	else
		printf("Server Startedn");
		
	if( listen( sock ,20 ) == -1 )
		printf("listening failed n");
		
	while(1){
		if( (Client_sock = accept(sock, (struct sockaddr *)NULL,NULL)) < 0 )
			printf("accept failed  n");
		pthread_mutex_lock(&mutex);
		clients[n]= Client_sock;
		n++;
		// creating a thread for each client 
		pthread_create(&recvt,NULL,(void *)recvmg,&Client_sock);
		pthread_mutex_unlock(&mutex);
	}
	return 0; 
	
}

client.c (client program )

#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <pthread.h>

char msg[500];

void *recvmg(void *my_sock)
{
	int sock = *((int *)my_sock);
	int len;
	// client thread always ready to receive message
	while((len = recv(sock,msg,500,0)) > 0) {
		msg[len] = '';
		fputs(msg,stdout);
	}
}

int main(int argc,char *argv[]){
	pthread_t recvt;
	int len;
	int sock;
	char send_msg[500];
	struct sockaddr_in ServerIp;
	char client_name[100];
	strcpy(client_name, argv[1]);
	sock = socket( AF_INET, SOCK_STREAM,0);
	ServerIp.sin_port = htons(1234);
	ServerIp.sin_family= AF_INET;
	ServerIp.sin_addr.s_addr = inet_addr("127.0.0.1");
	if( (connect( sock ,(struct sockaddr *)&ServerIp,sizeof(ServerIp))) == -1 )
		printf("n connection to socket failed n");
	
	//creating a client thread which is always waiting for a message
	pthread_create(&recvt,NULL,(void *)recvmg,&sock);
	
	//ready to read a message from console
	while(fgets(msg,500,stdin) > 0) {
		strcpy(send_msg,client_name);
		strcat(send_msg,":");
		strcat(send_msg,msg);
		len = write(sock,send_msg,strlen(send_msg));
		if(len < 0) 
			printf("n message not sent n");
	}
	
	//thread is closed
	pthread_join(recvt,NULL);
	close(sock);
	return 0;
}
		

Running server.c

gcc server.c -pthread
./a.out

Running client.c

gcc client.c -pthread
./a.out client_name

Output