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| /* |
| C socket server example, handles multiple clients using threads */ |
| |
| #include<stdio.h> |
| #include<string.h> //strlen |
| #include<stdlib.h> //strlen |
| #include<sys/socket.h> |
| #include<arpa/inet.h> //inet_addr |
| #include<unistd.h> |
| #//write |
| #include<pthread.h> |
| //for threading , link with lpthread |
| #define PORT 3210 |
| //the thread function |
| |
| |
| |
| void *connection_handler(void *); |
| |
| int is_connected = 0; |
| int ncalls=0; |
| |
| int writesock(int sock, char *msg, int len ){ |
| int hdr[2]; |
| hdr[0]=ncalls++; |
| hdr[1]= len + 8; |
| write(sock , hdr , 8); |
| return write(sock , msg , len); |
| } |
| |
| |
| int main(int argc , char *argv[]) { |
| int socket_desc , client_sock , c , *new_sock=NULL; |
| struct sockaddr_in server , client; |
| |
| //Create socket |
| socket_desc = socket(AF_INET , SOCK_STREAM , 0); |
| if (socket_desc == -1) |
| { |
| printf("Could not create socket"); |
| } |
| puts("Socket created"); |
| |
| //Prepare the sockaddr_in structure |
| server.sin_family = AF_INET; |
| server.sin_addr.s_addr = INADDR_ANY; |
| server.sin_port = htons( PORT ); |
| |
| //Bind |
| if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0) |
| { |
| //print the error message |
| perror("bind failed. Error"); |
| return 1; |
| } |
| puts("bind done"); |
| |
| //Listen |
| listen(socket_desc , 3); |
| |
| //Accept and incoming connection |
| puts("Waiting for incoming connections..."); |
| c = sizeof(struct sockaddr_in); |
| |
| |
| //Accept and incoming connection |
| puts("Waiting for incoming connections..."); |
| c = sizeof(struct sockaddr_in); |
| while( (client_sock = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)) ) |
| { |
| puts("Connection accepted"); |
| |
| pthread_t sniffer_thread; |
| |
| if (is_connected){ |
| char message[0xFF]="Only one client can connect. Disconnect it first!"; |
| perror(message); |
| writesock(client_sock , message , strlen(message)); |
| close (client_sock); |
| continue; |
| } |
| new_sock = (int *) malloc(1); |
| *new_sock = client_sock; |
| if( pthread_create( &sniffer_thread , NULL , connection_handler , (void*) new_sock) < 0) |
| { |
| perror("could not create thread"); |
| return 1; |
| } |
| |
| |
| //Now join the thread , so that we dont terminate before the thread |
| //pthread_join( sniffer_thread , NULL); |
| puts("Handler assigned"); |
| |
| } |
| |
| if (client_sock < 0) |
| { |
| perror("accept failed"); |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| |
| |
| void *daq_handler(void *data){ |
| |
| int s = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL); |
| //Get the socket descriptor |
| int sock = *(int*)data; |
| char msg[0xFF]; |
| int cnt=0; |
| while (1){ |
| sprintf(msg, "daq_handler %d %d", sock, cnt++); |
| int error = 0; |
| socklen_t len = sizeof (error); |
| int retval = getsockopt (sock, SOL_SOCKET, SO_ERROR, &error, &len); |
| if (retval!=0 || error!=0) break; |
| writesock(sock , msg , strlen(msg)); |
| sleep(5); |
| } |
| printf("Exiting thread %d", sock ) ; |
| |
| } |
| |
| /* |
| * This will handle connection for each client |
| * */ |
| |
| void *connection_handler(void *socket_desc) { |
| //Get the socket descriptor |
| int sock = *(int*)socket_desc; |
| int read_size; |
| char *message , client_message[2000]; |
| is_connected = 1; |
| //Send some messages to the client |
| message = "Info from connection handler\n"; |
| writesock(sock , message , strlen(message)); |
| |
| //Receive a message from client |
| pthread_t daq_thread = 0; |
| |
| while( (read_size = recv(sock , client_message , 2000 , 0)) > 0 ) |
| { |
| //Send the message back to client |
| int * hdr = (int *) client_message; |
| char *msg = &client_message[8]; |
| printf("Received %d bytes RECID = %d LEN %d\n",read_size, hdr[0], hdr[1]); |
| switch (hdr[0]){ |
| case 0: |
| hdr[0]= sock; |
| if( pthread_create( &daq_thread , NULL , daq_handler , (void*) &client_message) < 0) |
| { |
| perror("could not create daq thread"); |
| break ; |
| } |
| |
| break; |
| case 3: |
| if (daq_thread) { |
| pthread_cancel(daq_thread); |
| daq_thread = 0; |
| } |
| break; |
| default: break; |
| |
| } |
| writesock(sock , msg , strlen(msg)); |
| } |
| |
| if(read_size == 0) |
| { |
| puts("Client disconnected"); |
| fflush(stdout); |
| } |
| else if(read_size == -1) |
| { |
| perror("recv failed"); |
| |
| } |
| if (daq_thread) { |
| pthread_cancel(daq_thread); |
| daq_thread = 0; |
| } |
| |
| |
| //Free the socket pointer |
| free(socket_desc); |
| socket_desc = 0; |
| is_connected = 0; |
| |
| return 0; |
| } |
| |