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dns: fix QU response source port and IPv6 hop limits #35

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dns: fix QU response source port and IPv6 hop limits #35

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969a095
interface: fix IPv6 hop-limit socket options
massimomazzariol Aug 30, 2026
e868dac
dns: send QU responses from the mDNS socket
massimomazzariol Aug 30, 2026
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9 changes: 8 additions & 1 deletion cache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,14 @@ cache_gc_timer(struct uloop_timeout *timeout)
continue;
}
r->refresh += 50;
dns_send_question(r->iface, (struct sockaddr *)&r->from, r->record, r->type, 0);
/*
* Preserve refresh routing: multicast interfaces send a QU query
* to the mDNS group, while unicast interfaces query the cached peer.
*/
dns_send_question(r->iface,
interface_multicast(r->iface) ? NULL :
(struct sockaddr *)&r->from,
r->record, r->type, 0);
}

avl_for_each_element_safe(&services, s, avl, t) {
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5 changes: 1 addition & 4 deletions dns.c
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Original file line number Diff line number Diff line change
Expand Up @@ -589,11 +589,8 @@ parse_question(struct interface *iface, struct sockaddr *from, char *name, struc
char *host, *host6;

/* TODO: Multicast if more than one quarter of TTL has passed */
if (is_unicast) {
if (is_unicast)
to = from;
if (interface_multicast(iface))
iface = interface_get(iface->name, iface->type | SOCKTYPE_BIT_UNICAST);
}

DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name);

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12 changes: 4 additions & 8 deletions interface.c
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Original file line number Diff line number Diff line change
Expand Up @@ -78,10 +78,8 @@ interface_send_packet4(struct interface *iface, struct sockaddr_in *to, struct i
pkti->ipi_ifindex = iface->ifindex;

fd = ufd[iface->type].fd;
if (interface_multicast(iface)) {
if (interface_multicast(iface) && !to) {
a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
if (to)
fprintf(stderr, "Ignoring IPv4 address for multicast interface\n");
} else {
a.sin_addr.s_addr = to->sin_addr.s_addr;
a.sin_port = to->sin_port;
Expand Down Expand Up @@ -121,10 +119,8 @@ interface_send_packet6(struct interface *iface, struct sockaddr_in6 *to, struct
pkti->ipi6_ifindex = iface->ifindex;

fd = ufd[iface->type].fd;
if (interface_multicast(iface)) {
if (interface_multicast(iface) && !to) {
inet_pton(AF_INET6, MCAST_ADDR6, &a.sin6_addr);
if (to)
fprintf(stderr, "Ignoring IPv6 address for multicast interface\n");
} else {
a.sin6_addr = to->sin6_addr;
}
Expand Down Expand Up @@ -518,8 +514,8 @@ static int interface_init_socket(enum umdns_socket_type type, bool *mcast)
local.sin_port = htons(MCAST_PORT);
break;
case SOCK_MC_IPV6:
setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ittl, sizeof(ittl));
setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ittl, sizeof(ittl));
setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &yes, sizeof(yes));
setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &no, sizeof(no));
local6.sin6_port = htons(MCAST_PORT);
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