├── README.md
├── client.c
└── server.c


/README.md:
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 1 | # Multi-Client-Server-Chat
 2 | Group chat program where there is a single server and multiple clients. The server forwards a client's message to all the other clients.
 3 | 
 4 | <b>Platform:</b> Linux with GCC compiler
 5 | 
 6 | <b>Compiling:</b> gcc filename.c -pthread
 7 | 
 8 | <b>Running the server:</b> ./a.out portnumber
 9 | 
10 | <b>Running the clients:</b> ./a.out username portnumber
11 | 
12 | <b>Stopping the clients and server:</b> CTRL-D
13 | 
14 | <b>Note:</b> The portnumber provided to clients should be same as the one given to server. Username is just an identity of yourself.
15 | 


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/client.c:
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 1 | #include <sys/types.h>
 2 | #include <sys/socket.h>
 3 | #include <netinet/in.h>
 4 | #include <stdio.h>
 5 | #include <string.h>
 6 | #include <stdlib.h>
 7 | #include <unistd.h>
 8 | #include <arpa/inet.h>
 9 | #include <pthread.h>
10 | void *recvmg(void *sock)
11 | {
12 | 	int their_sock = *((int *)sock);
13 | 	char msg[500];
14 | 	int len;
15 | 	while((len = recv(their_sock,msg,500,0)) > 0) {
16 | 		msg[len] = '\0';
17 | 		fputs(msg,stdout);
18 | 		memset(msg,'\0',sizeof(msg));
19 | 	}
20 | }
21 | int main(int argc, char *argv[])
22 | {
23 | 	struct sockaddr_in their_addr;
24 | 	int my_sock;
25 | 	int their_sock;
26 | 	int their_addr_size;
27 | 	int portno;
28 | 	pthread_t sendt,recvt;
29 | 	char msg[500];
30 | 	char username[100];
31 | 	char res[600];
32 | 	char ip[INET_ADDRSTRLEN];
33 | 	int len;
34 | 
35 | 	if(argc > 3) {
36 | 		printf("too many arguments");
37 | 		exit(1);
38 | 	}
39 | 	portno = atoi(argv[2]);
40 | 	strcpy(username,argv[1]);
41 | 	my_sock = socket(AF_INET,SOCK_STREAM,0);
42 | 	memset(their_addr.sin_zero,'\0',sizeof(their_addr.sin_zero));
43 | 	their_addr.sin_family = AF_INET;
44 | 	their_addr.sin_port = htons(portno);
45 | 	their_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
46 | 
47 | 	if(connect(my_sock,(struct sockaddr *)&their_addr,sizeof(their_addr)) < 0) {
48 | 		perror("connection not esatablished");
49 | 		exit(1);
50 | 	}
51 | 	inet_ntop(AF_INET, (struct sockaddr *)&their_addr, ip, INET_ADDRSTRLEN);
52 | 	printf("connected to %s, start chatting\n",ip);
53 | 	pthread_create(&recvt,NULL,recvmg,&my_sock);
54 | 	while(fgets(msg,500,stdin) > 0) {
55 | 		strcpy(res,username);
56 | 		strcat(res,":");
57 | 		strcat(res,msg);
58 | 		len = write(my_sock,res,strlen(res));
59 | 		if(len < 0) {
60 | 			perror("message not sent");
61 | 			exit(1);
62 | 		}
63 | 		memset(msg,'\0',sizeof(msg));
64 | 		memset(res,'\0',sizeof(res));
65 | 	}
66 | 	pthread_join(recvt,NULL);
67 | 	close(my_sock);
68 | 
69 | }


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/server.c:
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  1 | #include <sys/types.h>
  2 | #include <sys/socket.h>
  3 | #include <netinet/in.h>
  4 | #include <stdio.h>
  5 | #include <string.h>
  6 | #include <stdlib.h>
  7 | #include <unistd.h>
  8 | #include <arpa/inet.h>
  9 | #include <pthread.h>
 10 | struct client_info {
 11 | 	int sockno;
 12 | 	char ip[INET_ADDRSTRLEN];
 13 | };
 14 | int clients[100];
 15 | int n = 0;
 16 | pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
 17 | void sendtoall(char *msg,int curr)
 18 | {
 19 | 	int i;
 20 | 	pthread_mutex_lock(&mutex);
 21 | 	for(i = 0; i < n; i++) {
 22 | 		if(clients[i] != curr) {
 23 | 			if(send(clients[i],msg,strlen(msg),0) < 0) {
 24 | 				perror("sending failure");
 25 | 				continue;
 26 | 			}
 27 | 		}
 28 | 	}
 29 | 	pthread_mutex_unlock(&mutex);
 30 | }
 31 | void *recvmg(void *sock)
 32 | {
 33 | 	struct client_info cl = *((struct client_info *)sock);
 34 | 	char msg[500];
 35 | 	int len;
 36 | 	int i;
 37 | 	int j;
 38 | 	while((len = recv(cl.sockno,msg,500,0)) > 0) {
 39 | 		msg[len] = '\0';
 40 | 		sendtoall(msg,cl.sockno);
 41 | 		memset(msg,'\0',sizeof(msg));
 42 | 	}
 43 | 	pthread_mutex_lock(&mutex);
 44 | 	printf("%s disconnected\n",cl.ip);
 45 | 	for(i = 0; i < n; i++) {
 46 | 		if(clients[i] == cl.sockno) {
 47 | 			j = i;
 48 | 			while(j < n-1) {
 49 | 				clients[j] = clients[j+1];
 50 | 				j++;
 51 | 			}
 52 | 		}
 53 | 	}
 54 | 	n--;
 55 | 	pthread_mutex_unlock(&mutex);
 56 | }
 57 | int main(int argc,char *argv[])
 58 | {
 59 | 	struct sockaddr_in my_addr,their_addr;
 60 | 	int my_sock;
 61 | 	int their_sock;
 62 | 	socklen_t their_addr_size;
 63 | 	int portno;
 64 | 	pthread_t sendt,recvt;
 65 | 	char msg[500];
 66 | 	int len;
 67 | 	struct client_info cl;
 68 | 	char ip[INET_ADDRSTRLEN];;
 69 | 	;
 70 | 	if(argc > 2) {
 71 | 		printf("too many arguments");
 72 | 		exit(1);
 73 | 	}
 74 | 	portno = atoi(argv[1]);
 75 | 	my_sock = socket(AF_INET,SOCK_STREAM,0);
 76 | 	memset(my_addr.sin_zero,'\0',sizeof(my_addr.sin_zero));
 77 | 	my_addr.sin_family = AF_INET;
 78 | 	my_addr.sin_port = htons(portno);
 79 | 	my_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
 80 | 	their_addr_size = sizeof(their_addr);
 81 | 
 82 | 	if(bind(my_sock,(struct sockaddr *)&my_addr,sizeof(my_addr)) != 0) {
 83 | 		perror("binding unsuccessful");
 84 | 		exit(1);
 85 | 	}
 86 | 
 87 | 	if(listen(my_sock,5) != 0) {
 88 | 		perror("listening unsuccessful");
 89 | 		exit(1);
 90 | 	}
 91 | 
 92 | 	while(1) {
 93 | 		if((their_sock = accept(my_sock,(struct sockaddr *)&their_addr,&their_addr_size)) < 0) {
 94 | 			perror("accept unsuccessful");
 95 | 			exit(1);
 96 | 		}
 97 | 		pthread_mutex_lock(&mutex);
 98 | 		inet_ntop(AF_INET, (struct sockaddr *)&their_addr, ip, INET_ADDRSTRLEN);
 99 | 		printf("%s connected\n",ip);
100 | 		cl.sockno = their_sock;
101 | 		strcpy(cl.ip,ip);
102 | 		clients[n] = their_sock;
103 | 		n++;
104 | 		pthread_create(&recvt,NULL,recvmg,&cl);
105 | 		pthread_mutex_unlock(&mutex);
106 | 	}
107 | 	return 0;
108 | }


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