static struct irec *add_iface(struct irec *list, unsigned int flags,
char *name, union mysockaddr *addr,
struct iname *names, struct iname *addrs)
{
struct irec *iface;
/* we may need to check the whitelist */
if (names)
{
struct iname *tmp;
for(tmp = names; tmp; tmp = tmp->next)
if (strcmp(tmp->name, name) == 0)
{
tmp->found = 1;
break;
}
if (!(flags & IFF_LOOPBACK) && !tmp)
/* not on whitelist and not loopback */
return list;
}
if (addrs)
{
struct iname *tmp;
for(tmp = addrs; tmp; tmp = tmp->next)
if (sockaddr_isequal(&tmp->addr, addr))
{
tmp->found = 1;
break;
}
if (!tmp)
/* not on whitelist */
return list;
}
/* check whether the interface IP has been added already
it is possible to have multiple interfaces with the same address. */
for (iface = list; iface; iface = iface->next)
if (sockaddr_isequal(&iface->addr, addr))
break;
if (iface)
return list;
/* If OK, add it to the head of the list */
iface = safe_malloc(sizeof(struct irec));
iface->addr = *addr;
iface->next = list;
return iface;
}
static struct frec *lookup_frec_by_sender(unsigned short id,
union mysockaddr *addr)
{
int i;
for(i=0; i<FTABSIZ; i++)
{
struct frec *f = &ftab[i];
if (f->new_id &&
f->orig_id == id &&
sockaddr_isequal(&f->source, addr))
return f;
}
return NULL;
}
/* 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 */
}
}