1 files changed, 120 insertions, 0 deletions
diff --git a/src/server.c b/src/server.c
new file mode 100644
index 0000000..4ca1985
--- /dev/null
+++ b/src/server.c
@@ -0,0 +1,120 @@
+/* main.c
+ * (c) Jonas Gunz, 2020
+ * License: MIT
+ * */
+
+#include "server.h"
+
+void run_dns_server ( void )
+{
+	int		ret;
+	struct		sockaddr_in sock_server_addr;
+
+	char recv_buffer[ UDP_BUFFER_LEN ];
+
+	signal ( SIGTERM, signal_term );
+	signal ( SIGINT,  signal_term );
+
+	//Avoid zombie processes
+	//TODO currently useless, since no forking is done.
+	signal (SIGCHLD, SIG_IGN);
+
+	log_init_stdout ( _LOG_DEBUG );
+
+	sock_server = socket ( AF_INET, SOCK_DGRAM, 0 );
+	if ( sock_server == -1 ) {
+		LOGPRINTF(_LOG_ERROR, "socket() failed");
+		exit ( errno );
+	}
+
+	memset( &sock_server_addr, '\0', sizeof(struct sockaddr_in) );
+	sock_server_addr.sin_family = AF_INET;
+	sock_server_addr.sin_port   = htons( 53 );
+	ret = inet_aton ( "0.0.0.0", & sock_server_addr.sin_addr );
+	if( ret == 0 ) { //Error on 0, no errno!
+		LOGPRINTF(_LOG_NOTE, "inet_aton(): Invalid bind IP\n" );
+		exit ( 1 );
+	}
+
+	ret = bind (	sock_server,
+			(struct sockaddr*) &sock_server_addr,
+			sizeof(struct sockaddr_in) );
+	if ( ret == -1 ) {
+		LOGPRINTF(_LOG_ERROR, "bind() failed");
+		exit ( errno );
+	}
+
+	while( 1 )
+	{
+		struct 		sockaddr_in sock_client_addr;
+		socklen_t	sock_client_addr_len;
+
+		sock_client_addr_len = sizeof ( struct sockaddr_in );
+		memset ( &sock_client_addr, '\0', sock_client_addr_len );
+
+		ret = recvfrom (sock_server,
+				recv_buffer,
+				UDP_BUFFER_LEN,
+				0,
+				(struct sockaddr*) &sock_client_addr,
+				&sock_client_addr_len );
+		if ( ret == -1 ) {
+			LOGPRINTF( _LOG_ERROR, "recvfrom()");
+			exit ( errno );
+		}
+
+		LOGPRINTF(_LOG_DEBUG, "UDP Packet size %i", ret);
+
+		handle_connection ( sock_server,
+				&sock_client_addr,
+				sock_client_addr_len,
+				recv_buffer,
+				ret );
+	}
+
+	close( sock_server );
+}
+
+int handle_connection (	int _socket,
+			struct sockaddr_in *sockaddr_client,
+			socklen_t sockaddr_client_len,
+			char* _buffer,
+			int _bufflen )
+{
+	struct dns_message msg;
+
+	if (dns_parse_packet (_buffer, _bufflen, &msg) ) {
+		LOGPRINTF (_LOG_DEBUG, "Malformed packet recieved. parsing failed");
+		return 1;
+	}
+
+	if(msg.question_count > 0) {
+		char out[128];
+		qname_to_fqdn( (char*) msg.question[0].qname, 100, out, 128);
+		printf("%s %i\n", out, msg.question[0].qtype);
+	}
+	
+	dns_destroy_struct ( &msg );
+
+	//Always return NXDOMAIN
+	struct dns_header head = {msg.header.id,1,OP_Q,0,0,0,0,0,NAMEERR,0,0,0,0};
+	char ret[20];
+	int retlen = dns_construct_header ( &head, ret, 20 );
+	sendto (_socket, ret, retlen, 0, (struct sockaddr*) sockaddr_client, sockaddr_client_len);
+	
+	return 0;
+}
+
+void signal_term ( ) {
+	printf( "Recieved Signal. Terminating active connections and closing socket\n" );
+
+	//terminate all children >:)
+	kill ( 0, SIGTERM ); 
+
+	shutdown ( sock_server, SHUT_RDWR );
+	close ( sock_server );
+
+	printf( "done\n" );
+
+	exit( 0 );
+}