void dns_handle_new_query(dns_request_t *m)
{
//struct in_addr in;
int retval = 0; /* modified by CMC from retval=-1 2002/12/6 */
if( m->message.question[0].type == A || m->message.question[0].type == AAA){
/* added by CMC to deny name 2002/11/19 */
if ( deny_lookup_name( m->cname ) )
{
debug("%s --> blocked.\n", m->cname);
openlog("URL Filter", 0, 0);
syslog(0, "URL access to %s is blocked\n", m->cname);
closelog();
dns_construct_error_reply(m);
dns_write_packet( dns_sock, m->src_addr, m->src_port, m );
return;
}
/* standard query */
retval = cache_lookup_name( m->cname, m->ip );
}else if( m->message.question[0].type == PTR ){
/* reverse lookup */
retval = cache_lookup_ip( m->ip, m->cname );
}
debug(".......... %s ---- %s\n", m->cname, m->ip );
switch( retval )
{
case 0:
if( is_connected() ){
debug("Adding to list-> id: %d\n", m->message.header.id);
dns_request_list = dns_list_add( dns_request_list, m );
/* relay the query untouched */
forward_dns_query( dns_request_list, m ); /* modified by CMC 8/3/2001 */
}else{
debug("Not connected **\n");
dns_construct_error_reply(m);
dns_write_packet( dns_sock, m->src_addr, m->src_port, m );
}
break;
case 1:
dns_construct_reply( m );
dns_write_packet( dns_sock, m->src_addr, m->src_port, m );
debug("Cache hit\n");
break;
default:
debug("Unknown query type: %d\n", m->message.question[0].type );
debug("CMC: Here is un-reachable code! (2002/12/6)\n");
}
}
void dns_handle_request(dns_request_t *m)
{
dns_request_t *ptr = NULL;
/* request may be a new query or a answer from the upstream server */
ptr = dns_list_find_by_id( dns_request_list, m );
if( ptr != NULL ){
debug("Found query in list\n");
/* message may be a response */
if( m->message.header.flags.f.question == 1 ){
dns_write_packet( dns_sock, ptr->src_addr, ptr->src_port, m );
debug("Replying with answer from %s\n", inet_ntoa( m->src_addr ));
if( m->message.header.flags.f.rcode == 0 && /* modified by CMC 2002/12/6 */
(ptr->message.question[0].type == A || ptr->message.question[0].type == PTR) ){
debug("Cache append: %s ----> %s\n", m->cname, m->ip );
cache_name_append( m->cname, m->ip );
}
dns_request_list = dns_list_remove( dns_request_list, ptr );
}else{
ptr->duplicate_queries++; /* added by CMC 8/4/2001 */
debug("Duplicate query(%d)\n", ptr->duplicate_queries);
forward_dns_query( ptr, m ); /* added by CMC 8/4/2001 */
}
}else{
dns_handle_new_query( m );
}
}
void dns_handle_new_query(dns_request_t *m)
{
struct in_addr in;
int retval = -1;
if( m->message.question[0].type == A || m->message.question[0].type == AAA){
/* standard query */
retval = cache_lookup_name( m->cname, m->ip );
}else if( m->message.question[0].type == PTR ){
/* reverse lookup */
retval = cache_lookup_ip( m->ip, m->cname );
}
debug(".......... %s ---- %s\n", m->cname, m->ip );
switch( retval )
{
case 0:
if( is_connected() ){
debug("Adding to list-> id: %d\n", m->message.header.id);
dns_request_list = dns_list_add( dns_request_list, m );
/*!!! relay the query untouched */
inet_aton( config.name_server[0], &in );
debug("Sent Request To %s\n",config.name_server[0]);
dns_write_packet( dns_sock, in, PORT, m );
}else{
debug("Not connected **\n");
dns_construct_error_reply(m);
dns_write_packet( dns_sock, m->src_addr, m->src_port, m );
}
break;
case 1:
dns_construct_reply( m );
dns_write_packet( dns_sock, m->src_addr, m->src_port, m );
debug("Cache hit\n");
break;
default:
debug("Unknown query type: %d\n", m->message.question[0].type );
}
}
int dns_main_loop()
{
struct timeval tv;
fd_set active_rfds;
int retval;
dns_request_t m;
dns_request_t *ptr, *next;
//int purge_time = config.purge_time / 60;
int purge_time = CACHE_CHECK_TIME / DNS_TICK_TIME; //(30sec) modified by CMC 8/4/2001
while( !dns_main_quit ){
/* set the one second time out */
tv.tv_sec = DNS_TICK_TIME; //modified by CMC 8/3/2001
tv.tv_usec = 0;
/* now copy the main rfds in the active one as it gets modified by select*/
active_rfds = rfds;
retval = select( FD_SETSIZE, &active_rfds, NULL, NULL, &tv );
if (retval){
/* data is now available */
dns_read_packet( dns_sock, &m );
dns_handle_request( &m );
}else{
/* select time out */
ptr = dns_request_list;
while( ptr ){
next = ptr->next;
ptr->time_pending++;
if( ptr->time_pending > DNS_TIMEOUT/DNS_TICK_TIME ){
/* CMC: ptr->time_pending= DNS_TIMEOUT ~ DNS_TIMEOUT+DNS_TICK_TIME */
debug("Request timed out\n");
/* send error back */
dns_construct_error_reply(ptr);
dns_write_packet( dns_sock, ptr->src_addr, ptr->src_port, ptr );
dns_request_list = dns_list_remove( dns_request_list, ptr );
}
ptr = next;
} /* while(ptr) */
/* purge cache */
purge_time--;
if( purge_time <= 0 ){ //modified by CMC 8/4/2001
cache_purge( config.purge_time );
//purge_time = config.purge_time / 60;
purge_time = CACHE_CHECK_TIME / DNS_TICK_TIME; //(30sec) modified by CMC 8/3/2001
}
} /* if (retval) */
}
return 0;
}
/* This function is added by CMC 8/4/2001 */
void forward_dns_query(dns_request_t *node, dns_request_t *m)
{
struct in_addr in;
FILE *fp;
char line[81], dns_ser_ip[81];
inet_aton( config.name_server, &in );
if( (fp = fopen( "/etc/resolv.conf" , "r")) != NULL) {
while ( fgets(line, 80, fp) != NULL ){
if ( sscanf(line, "nameserver %s", dns_ser_ip) == 1 ){
inet_aton( dns_ser_ip, &in );
/* the first or lastest nameserver */
if ( !(node->duplicate_queries & 0x01) )
break;
}
}
fclose(fp);
}
debug("forward_dns_query: query DNS server -- %s\n", inet_ntoa(in) );
dns_write_packet( dns_sock, in, PORT, m );
}
void dns_handle_request(dns_request_t *m)
{
dns_request_t *ptr = NULL;
/* request may be a new query or a answer from the upstream server */
ptr = dns_list_find_by_id( dns_request_list, m );
if( ptr != NULL ){
debug("Found query in list\n");
/* message may be a response */
if( m->message.header.flags.f.question == 1 ){
if( m->message.header.flags.f.rcode == 0 ){ // lookup was succesful
dns_write_packet( dns_sock, ptr->src_addr, ptr->src_port, m );
debug("Replying with answer from %s\n", inet_ntoa( m->src_addr ));
dns_request_list = dns_list_remove( dns_request_list, ptr );
debug("Cache append: %s ----> %s\n", m->cname, m->ip );
cache_name_append( m->cname, m->ip );
}
/*if( m->message.header.flags.f.question == 1 ){
dns_write_packet( dns_sock, ptr->src_addr, ptr->src_port, m );
debug("Replying with answer from %s\n", inet_ntoa( m->src_addr ));
dns_request_list = dns_list_remove( dns_request_list, ptr );
if( m->message.header.flags.f.rcode == 0 ){ // lookup was succesful
debug("Cache append: %s ----> %s\n", m->cname, m->ip );
cache_name_append( m->cname, m->ip );
}*/
}else{
debug("Duplicate query\n");
}
}else{
dns_handle_new_query( m );
}
}
int dns_main_loop()
{
struct timeval tv;
fd_set active_rfds;
int retval;
dns_request_t m;
dns_request_t *ptr, *next;
int purge_time = config.purge_time / 60;
int next_server_index = 0;
struct in_addr in;
while( !dns_main_quit ){
/* set the one second time out */
tv.tv_sec = 1;
tv.tv_usec = 0;
/* now copy the main rfds in the active one as it gets modified by select*/
active_rfds = rfds;
retval = select( FD_SETSIZE, &active_rfds, NULL, NULL, &tv );
if (retval){
/* data is now available */
dns_read_packet( dns_sock, &m );
m.time_pending = 0;
dns_handle_request( &m );
}else{
/* select time out */
ptr = dns_request_list;
while( ptr ){
next = ptr->next;
/* Resend query to a new nameserver if response
* has not been received from the current nameserver */
ptr->time_pending++;
if( ptr->time_pending > DNS_TIMEOUT ){
debug("Request timed out\n");
/* send error back */
dns_construct_error_reply(ptr);
dns_write_packet( dns_sock, ptr->src_addr, ptr->src_port, ptr );
dns_request_list = dns_list_remove( dns_request_list, ptr );
}
if( ( ptr->time_pending % DNS_SERVER_TIMEOUT == 0) &&
( ptr->time_pending < DNS_TIMEOUT) )
{
/* Send a request to the next nameserver */
next_server_index = ptr->time_pending/DNS_SERVER_TIMEOUT;
/* If already the maximum number of supported servers have
been tried out then remove the request from the list and
send a response back */
if(next_server_index >= MAX_NAME_SERVER ||
(config.name_server[next_server_index] == NULL ))
{
/* send error back */
debug("All Servers Tried: No Response\n");
dns_construct_error_reply(ptr);
dns_write_packet( dns_sock, ptr->src_addr, ptr->src_port, ptr );
dns_request_list = dns_list_remove( dns_request_list, ptr );
debug("Sent a DNS error message to Client \n");
}
else
{
/* Create the new server IP address and relay the query untouched */
inet_aton( config.name_server[next_server_index], &in );
/*!!!*/
debug("Didn't get a response from last server\n");
debug("Sending a new request to %s\n", config.name_server[next_server_index]);
/* Send the new request to the next name server */
dns_write_packet( dns_sock, in, PORT, ptr );
}
}
ptr = next;
} /* while(ptr) */
/* purge cache */
purge_time--;
if( !purge_time ){
cache_purge( config.purge_time );
purge_time = config.purge_time / 60;
}
} /* if (retval) */
}
return 0;
}
