├── README.md
├── Send_Structure_for_Authentication_Client
├── Send_Structure_for_Authentication_Server
├── tcpClient.c
└── tcpServer.c


/README.md:
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1 | # Multiple-Client-Server-Program-in-C-using-fork
2 | A simple tcp client server application that describes the communication between the client and a server. The server is a simple echo sever that can handle multiple client using fork.
3 | 
4 | An echo server is a server that send back the same message that the client has send the server. 
5 | Like:
6 | 
7 | Client send - abc<br/>
8 | Server recv - abc
9 | 


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/Send_Structure_for_Authentication_Client:
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 1 | #include<stdio.h>
 2 | #include<stdlib.h>
 3 | #include<sys/types.h>
 4 | #include<sys/socket.h>
 5 | #include<netinet/in.h>
 6 | #include<string.h>
 7 | struct myStruct{
 8 | 	char name[10];
 9 | 	int userId;
10 | 	char password[10];
11 | };
12 | int main(){
13 | 	int sockfd;
14 | 	struct sockaddr_in server;
15 | 	sockfd = socket(AF_INET, SOCK_STREAM, 0);
16 | 	if(sockfd==-1){
17 | 		printf("Socket not created\n");
18 | 		exit(0);
19 | 	}else{
20 | 		printf("Socket Created\n");
21 | 	}
22 | 	server.sin_family = AF_INET;
23 | 	server.sin_port = htons(3050);
24 | 	server.sin_addr.s_addr = INADDR_ANY;
25 | 	
26 | 	
27 | 	int x=connect(sockfd, (struct sockaddr *)&server, sizeof(server));
28 | 	if(x==-1){
29 | 		printf("Connection Failure\n");
30 | 		exit(0);
31 | 	}
32 | 	
33 | 	struct myStruct myst;
34 | 	printf("Enter userId : "); 
35 | 	scanf("%d",&myst.userId);
36 | 	printf("Enter password : "); 
37 | 	scanf("%s",myst.password);
38 | 
39 | 	
40 | 	send(sockfd,&myst,sizeof(myst),0);
41 | 	
42 | 	char message[20];
43 | 	recv(sockfd, message, sizeof(message), 0);
44 | 	
45 | 	printf("%s",message);
46 | 	
47 | 	
48 | 	close(sockfd);
49 | 	return 0;
50 | }
51 | 


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/Send_Structure_for_Authentication_Server:
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 1 | #include<stdio.h>
 2 | #include<stdlib.h>
 3 | #include<sys/types.h>
 4 | #include<sys/socket.h>
 5 | #include<netinet/in.h>
 6 | #include<string.h>
 7 | struct myStruct{
 8 | 	char name[10];
 9 | 	int userId;
10 | 	char password[10];
11 | };
12 | int main(){
13 | 	int sockfd;
14 | 	struct sockaddr_in server,client;
15 | 	
16 | 	sockfd = socket(AF_INET, SOCK_STREAM, 0);
17 | 	if(sockfd==-1){
18 | 		printf("Socket not created\n");
19 | 		exit(0);
20 | 	}else{
21 | 		printf("Socket Created\n");
22 | 	}
23 | 	
24 | 	server.sin_family = AF_INET;
25 | 	server.sin_port = htons(3050);
26 | 	server.sin_addr.s_addr = INADDR_ANY;
27 | 	//INET_ADDR("127.0.0.1")
28 | 	int x=bind(sockfd, (struct sockaddr *)&server, sizeof(server));
29 | 	if(x==-1){
30 | 		printf("bind Failure\n");
31 | 		exit(0);
32 | 	}else{
33 | 		printf("bind Successful\n");
34 | 	}
35 | 	
36 | 	listen(sockfd, 5);
37 | 	int s=sizeof(client);
38 | 	
39 | 	struct myStruct st[5]={{"nikhil1",1,"nikhil1"},
40 | 						   {"nikhil2",2,"nikhil2"},
41 | 						   {"nikhil3",3,"nikhil3"},
42 | 						   {"nikhil14",4,"nikhil4"},
43 | 						   {"nikhil5",5,"nikhil15"}};
44 | 	struct myStruct myst;
45 | 	int fd1=accept(sockfd, (struct sockaddr *)&client, &s);
46 | 	
47 | 	recv(fd1, &myst, sizeof(myst), 0);
48 | 	//recvfrom(sockfd,buff,100,0,(struct sockaddr *)&client,&s);
49 | 	
50 | 	printf("userId received :%d\n",myst.userId);
51 | 	printf("password received :%s\n",myst.password);
52 | 	int fl=1;
53 | 	for(int i=0;i<5;i++){
54 | 		if(myst.userId==st[i].userId && strcmp(myst.password,st[i].password)==0){
55 | 			fl=0;
56 | 			break;
57 | 		}
58 | 	}
59 | 	
60 | 	
61 | 	if(fl==0){		
62 | 		char message[20]="Login Successful\n";
63 | 		send(fd1, message, sizeof(message), 0);
64 | 	}else{
65 | 		char message[20]="Login Failure\n";
66 | 		send(fd1, message, sizeof(message), 0);
67 | 	}	
68 | 	
69 | 	
70 | 	close(sockfd);
71 | 	return 0;
72 | }
73 | 


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/tcpClient.c:
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 1 | #include <stdio.h>
 2 | #include <stdlib.h>
 3 | #include <string.h>
 4 | #include <unistd.h>
 5 | #include <sys/socket.h>
 6 | #include <sys/types.h>
 7 | #include <netinet/in.h>
 8 | #include <arpa/inet.h>
 9 | 
10 | #define PORT 4444
11 | 
12 | int main(){
13 | 
14 | 	int clientSocket, ret;
15 | 	struct sockaddr_in serverAddr;
16 | 	char buffer[1024];
17 | 
18 | 	clientSocket = socket(AF_INET, SOCK_STREAM, 0);
19 | 	if(clientSocket < 0){
20 | 		printf("[-]Error in connection.\n");
21 | 		exit(1);
22 | 	}
23 | 	printf("[+]Client Socket is created.\n");
24 | 
25 | 	memset(&serverAddr, '\0', sizeof(serverAddr));
26 | 	serverAddr.sin_family = AF_INET;
27 | 	serverAddr.sin_port = htons(PORT);
28 | 	serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
29 | 
30 | 	ret = connect(clientSocket, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
31 | 	if(ret < 0){
32 | 		printf("[-]Error in connection.\n");
33 | 		exit(1);
34 | 	}
35 | 	printf("[+]Connected to Server.\n");
36 | 
37 | 	while(1){
38 | 		printf("Client: \t");
39 | 		scanf("%s", &buffer[0]);
40 | 		send(clientSocket, buffer, strlen(buffer), 0);
41 | 
42 | 		if(strcmp(buffer, ":exit") == 0){
43 | 			close(clientSocket);
44 | 			printf("[-]Disconnected from server.\n");
45 | 			exit(1);
46 | 		}
47 | 
48 | 		if(recv(clientSocket, buffer, 1024, 0) < 0){
49 | 			printf("[-]Error in receiving data.\n");
50 | 		}else{
51 | 			printf("Server: \t%s\n", buffer);
52 | 		}
53 | 	}
54 | 
55 | 	return 0;
56 | }


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/tcpServer.c:
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 1 | #include <stdio.h>
 2 | #include <stdlib.h>
 3 | #include <string.h>
 4 | #include <unistd.h>
 5 | #include <sys/socket.h>
 6 | #include <sys/types.h>
 7 | #include <netinet/in.h>
 8 | #include <arpa/inet.h>
 9 | 
10 | #define PORT 4444
11 | 
12 | int main(){
13 | 
14 | 	int sockfd, ret;
15 | 	 struct sockaddr_in serverAddr;
16 | 
17 | 	int newSocket;
18 | 	struct sockaddr_in newAddr;
19 | 
20 | 	socklen_t addr_size;
21 | 
22 | 	char buffer[1024];
23 | 	pid_t childpid;
24 | 
25 | 	sockfd = socket(AF_INET, SOCK_STREAM, 0);
26 | 	if(sockfd < 0){
27 | 		printf("[-]Error in connection.\n");
28 | 		exit(1);
29 | 	}
30 | 	printf("[+]Server Socket is created.\n");
31 | 
32 | 	memset(&serverAddr, '\0', sizeof(serverAddr));
33 | 	serverAddr.sin_family = AF_INET;
34 | 	serverAddr.sin_port = htons(PORT);
35 | 	serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
36 | 
37 | 	ret = bind(sockfd, (struct sockaddr*)&serverAddr, sizeof(serverAddr));
38 | 	if(ret < 0){
39 | 		printf("[-]Error in binding.\n");
40 | 		exit(1);
41 | 	}
42 | 	printf("[+]Bind to port %d\n", 4444);
43 | 
44 | 	if(listen(sockfd, 10) == 0){
45 | 		printf("[+]Listening....\n");
46 | 	}else{
47 | 		printf("[-]Error in binding.\n");
48 | 	}
49 | 
50 | 
51 | 	while(1){
52 | 		newSocket = accept(sockfd, (struct sockaddr*)&newAddr, &addr_size);
53 | 		if(newSocket < 0){
54 | 			exit(1);
55 | 		}
56 | 		printf("Connection accepted from %s:%d\n", inet_ntoa(newAddr.sin_addr), ntohs(newAddr.sin_port));
57 | 
58 | 		if((childpid = fork()) == 0){
59 | 			close(sockfd);
60 | 
61 | 			while(1){
62 | 				recv(newSocket, buffer, 1024, 0);
63 | 				if(strcmp(buffer, ":exit") == 0){
64 | 					printf("Disconnected from %s:%d\n", inet_ntoa(newAddr.sin_addr), ntohs(newAddr.sin_port));
65 | 					break;
66 | 				}else{
67 | 					printf("Client: %s\n", buffer);
68 | 					send(newSocket, buffer, strlen(buffer), 0);
69 | 					bzero(buffer, sizeof(buffer));
70 | 				}
71 | 			}
72 | 		}
73 | 
74 | 	}
75 | 
76 | 	close(newSocket);
77 | 
78 | 
79 | 	return 0;
80 | }


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