/* return unique random ids between 1 and 65535 */
static unsigned short get_id(void)
{
unsigned short ret = 0;
while (ret == 0)
{
ret = rand16();
/* scrap ids already in use */
if ((ret != 0) && lookup_frec(ret))
ret = 0;
}
return ret;
}
/* sets new last_server */
void reply_query(int fd, int family, time_t now)
{
/* packet from peer server, extract data for cache, and send to
original requester */
HEADER *header;
union mysockaddr serveraddr;
struct frec *forward;
socklen_t addrlen = sizeof(serveraddr);
ssize_t n = recvfrom(fd, daemon->packet, daemon->edns_pktsz, 0, &serveraddr.sa, &addrlen);
size_t nn;
struct server *server;
/* packet buffer overwritten */
daemon->srv_save = NULL;
/* Determine the address of the server replying so that we can mark that as good */
serveraddr.sa.sa_family = family;
#ifdef HAVE_IPV6
if (serveraddr.sa.sa_family == AF_INET6)
serveraddr.in6.sin6_flowinfo = 0;
#endif
/* spoof check: answer must come from known server, */
for (server = daemon->servers; server; server = server->next)
if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_NO_ADDR)) &&
sockaddr_isequal(&server->addr, &serveraddr))
break;
header = (HEADER *)daemon->packet;
if (!server ||
n < (int)sizeof(HEADER) || !header->qr ||
!(forward = lookup_frec(ntohs(header->id), questions_crc(header, n, daemon->namebuff))))
return;
server = forward->sentto;
if ((header->rcode == SERVFAIL || header->rcode == REFUSED) &&
!(daemon->options & OPT_ORDER) &&
forward->forwardall == 0)
/* for broken servers, attempt to send to another one. */
{
unsigned char *pheader;
size_t plen;
int is_sign;
/* recreate query from reply */
pheader = find_pseudoheader(header, (size_t)n, &plen, NULL, &is_sign);
if (!is_sign)
{
header->ancount = htons(0);
header->nscount = htons(0);
header->arcount = htons(0);
if ((nn = resize_packet(header, (size_t)n, pheader, plen)))
{
header->qr = 0;
header->tc = 0;
forward_query(-1, NULL, NULL, 0, header, nn, now, forward);
return;
}
}
}
if ((forward->sentto->flags & SERV_TYPE) == 0)
{
if (header->rcode == SERVFAIL || header->rcode == REFUSED)
server = NULL;
else
{
struct server *last_server;
/* find good server by address if possible, otherwise assume the last one we sent to */
for (last_server = daemon->servers; last_server; last_server = last_server->next)
if (!(last_server->flags & (SERV_LITERAL_ADDRESS | SERV_HAS_DOMAIN | SERV_FOR_NODOTS | SERV_NO_ADDR)) &&
sockaddr_isequal(&last_server->addr, &serveraddr))
{
server = last_server;
break;
}
}
if (!(daemon->options & OPT_ALL_SERVERS))
daemon->last_server = server;
}
/* If the answer is an error, keep the forward record in place in case
we get a good reply from another server. Kill it when we've
had replies from all to avoid filling the forwarding table when
everything is broken */
if (forward->forwardall == 0 || --forward->forwardall == 1 ||
(header->rcode != REFUSED && header->rcode != SERVFAIL))
{
if ((nn = process_reply(header, now, server, (size_t)n)))
{
header->id = htons(forward->orig_id);
header->ra = 1; /* recursion if available */
send_from(forward->fd, daemon->options & OPT_NOWILD, daemon->packet, nn,
&forward->source, &forward->dest, forward->iface);
}
free_frec(forward); /* cancel */
}
}
/* returns new last_server */
struct server *reply_query(int fd, char *packet, char *dnamebuff, struct server *last_server,unsigned long *timetolive)
{
/* packet from peer server, extract data for cache, and send to
original requester */
struct frec *forward;
HEADER *header;
int n = recv(fd, packet, PACKETSZ, 0);
header = (HEADER *)packet;
if (n >= (int)sizeof(HEADER) && header->qr)
{
if ((forward = lookup_frec(ntohs(header->id))))
{
//if (header->rcode == NOERROR || header->rcode == NXDOMAIN)
if (header->rcode == NOERROR)
{
/* ******* zg porting DWG814I Source code on 2006.11.06 ******* */
/* ******* To fixed cdrouterv3.3 item 333(dna_45) item 334(dns_45) failed bug ******* */
if(forward ->dnsMsgBufPtr != NULL)
{
free_dns_msg_buf(forward ->dnsMsgBufPtr);
forward ->dnsMsgBufPtr = NULL;
}
/* ******* end by zg porting DWG814I Source code on 2006.11.06 ******* */
if (!forward->sentto->domain)
last_server = forward->sentto; /* known good */
if (header->opcode == QUERY) {
strncpy(query_name, dnamebuff, sizeof(query_name));
extract_addresses(header, (unsigned int)n, dnamebuff, timetolive);
}
header->id = htons(forward->orig_id);
/* There's no point returning an upstream reply marked as truncated,
since that will prod the resolver into moving to TCP - which we
don't support. */
header->tc = 0; /* goodbye truncate */
sendto(forward->fd, packet, n, 0,
&forward->source.sa, sa_len(&forward->source));
forward->new_id = 0; /* cancel */
}
/* ******* zg porting DWG814I Source code on 2006.11.06 ******* */
/* ******* To fixed cdrouterv3.3 item 333(dna_45) item 334(dns_45) failed bug ******* */
else switch(header->rcode)
{
case SERVFAIL:
case NOTIMP:
case REFUSED:
//DBG_printf("SERVER fail, not implement, refuse, try next server\n");
break;
default:
//DBG_printf("SERVER response general error, return it to client\n");
if(forward ->dnsMsgBufPtr != NULL)
{
free_dns_msg_buf(forward ->dnsMsgBufPtr);
forward ->dnsMsgBufPtr = NULL;
}
header->id = htons(forward->orig_id);
/* There's no point returning an upstream reply marked as truncated,
since that will prod the resolver into moving to TCP - which we
don't support. */
header->tc = 0; /* goodbye truncate */
sendto(forward->fd, packet, n, 0,
&forward->source.sa, sa_len(&forward->source));
forward->new_id = 0; /* cancel */
break;
}
/* ******* end by zg porting DWG814I Source code on 2006.11.06 ******* */
}
}
return last_server;
}
