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-rw-r--r--src/resolve/resolved-dns-packet.c55
-rw-r--r--src/resolve/resolved-dns-packet.h1
2 files changed, 56 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index 40b662246f..49c36e38f3 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -609,6 +609,57 @@ fail:
return r;
}
+/* Append the OPT pseudo-RR described in RFC6891 */
+int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, size_t *start) {
+ size_t saved_size;
+ int r;
+
+ assert(p);
+ /* we must never advertise supported packet size smaller than the legacy max */
+ assert(max_udp_size >= DNS_PACKET_UNICAST_SIZE_MAX);
+
+ saved_size = p->size;
+
+ /* empty name */
+ r = dns_packet_append_uint8(p, 0, NULL);
+ if (r < 0)
+ return r;
+
+ /* type */
+ r = dns_packet_append_uint16(p, DNS_TYPE_OPT, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* maximum udp packet that can be received */
+ r = dns_packet_append_uint16(p, max_udp_size, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* extended RCODE and VERSION */
+ r = dns_packet_append_uint16(p, 0, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* flags */
+ r = dns_packet_append_uint16(p, 0, NULL);
+ if (r < 0)
+ goto fail;
+
+ /* RDLENGTH */
+ r = dns_packet_append_uint16(p, 0, NULL);
+ if (r < 0)
+ goto fail;
+
+ if (start)
+ *start = saved_size;
+
+ return 0;
+
+fail:
+ dns_packet_truncate(p, saved_size);
+ return r;
+}
+
int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) {
size_t saved_size, rdlength_offset, end, rdlength;
int r;
@@ -1450,6 +1501,10 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
r = dns_packet_read_name(p, &rr->ptr.name, true, NULL);
break;
+ case DNS_TYPE_OPT: /* we only care about the header */
+ r = 0;
+ break;
+
case DNS_TYPE_HINFO:
r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
if (r < 0)
diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index 90b5a7c8bd..ca94a208ba 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -160,6 +160,7 @@ int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start
int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, size_t *start);
int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start);
int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start);
+int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, size_t *start);
int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start);
int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start);