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resolved: add cache-flush bit to answers in mDNS announcements 

See the section 10.2 of RFC6762 for details.

Signed-off-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>
This commit is contained in:
Dmitry Rozhkov 2016-12-02 15:28:14 +02:00
parent 53fda2bb93
commit 58ab31d57f
8 changed files with 24 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/resolve/resolved-dns-answer.h
View File

@ -36,6 +36,7 @@ typedef enum DnsAnswerFlags {
DNS_ANSWER_AUTHENTICATED = 1, /* Item has been authenticated */
DNS_ANSWER_CACHEABLE = 2, /* Item is subject to caching */
DNS_ANSWER_SHARED_OWNER = 4, /* For mDNS: RRset may be owner by multiple peers */
DNS_ANSWER_CACHE_FLUSH = 8, /* For mDNS: sets cache-flush bit in the rrclass of response records */
} DnsAnswerFlags;
struct DnsAnswerItem {

4
src/resolve/resolved-dns-cache.c
View File

@ -980,7 +980,7 @@ int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
if (!j->shared_owner)
continue;
r = dns_packet_append_rr(p, j->rr, NULL, NULL);
r = dns_packet_append_rr(p, j->rr, 0, NULL, NULL);
if (r == -EMSGSIZE && p->protocol == DNS_PROTOCOL_MDNS) {
/* For mDNS, if we're unable to stuff all known answers into the given packet,
* allocate a new one, push the RR into that one and link it to the current one.
@ -995,7 +995,7 @@ int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
/* continue with new packet */
p = p->more;
r = dns_packet_append_rr(p, j->rr, NULL, NULL);
r = dns_packet_append_rr(p, j->rr, 0, NULL, NULL);
}
if (r < 0)

17
src/resolve/resolved-dns-packet.c
View File

@ -569,8 +569,9 @@ fail:
return r;
}
int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start) {
int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, const DnsAnswerFlags flags, size_t *start) {
size_t saved_size;
uint16_t class;
int r;
assert(p);
@ -586,7 +587,8 @@ int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start)
if (r < 0)
goto fail;
r = dns_packet_append_uint16(p, k->class, NULL);
class = flags & DNS_ANSWER_CACHE_FLUSH ? k->class | MDNS_RR_CACHE_FLUSH : k->class;
r = dns_packet_append_uint16(p, class, NULL);
if (r < 0)
goto fail;
@ -791,7 +793,7 @@ int dns_packet_truncate_opt(DnsPacket *p) {
return 1;
}
int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start) {
int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, const DnsAnswerFlags flags, size_t *start, size_t *rdata_start) {
size_t saved_size, rdlength_offset, end, rdlength, rds;
int r;
@ -801,7 +803,7 @@ int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *star
saved_size = p->size;
r = dns_packet_append_key(p, rr->key, NULL);
r = dns_packet_append_key(p, rr->key, flags, NULL);
if (r < 0)
goto fail;
@ -1143,7 +1145,7 @@ int dns_packet_append_question(DnsPacket *p, DnsQuestion *q) {
assert(p);
DNS_QUESTION_FOREACH(key, q) {
r = dns_packet_append_key(p, key, NULL);
r = dns_packet_append_key(p, key, 0, NULL);
if (r < 0)
return r;
}
@ -1153,12 +1155,13 @@ int dns_packet_append_question(DnsPacket *p, DnsQuestion *q) {
int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a) {
DnsResourceRecord *rr;
DnsAnswerFlags flags;
int r;
assert(p);
DNS_ANSWER_FOREACH(rr, a) {
r = dns_packet_append_rr(p, rr, NULL, NULL);
DNS_ANSWER_FOREACH_FLAGS(rr, flags, a) {
r = dns_packet_append_rr(p, rr, flags, NULL, NULL);
if (r < 0)
return r;
}

4
src/resolve/resolved-dns-packet.h
View File

@ -209,8 +209,8 @@ int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start);
int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start);
int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, bool canonical_candidate, size_t *start);
int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, bool canonical_candidate, 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, size_t *rdata_start);
int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, const DnsAnswerFlags flags, size_t *start);
int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, const DnsAnswerFlags flags, size_t *start, size_t *rdata_start);
int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, int rcode, size_t *start);
int dns_packet_append_question(DnsPacket *p, DnsQuestion *q);
int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a);

2
src/resolve/resolved-dns-rr.c
View File

@ -1262,7 +1262,7 @@ int dns_resource_record_to_wire_format(DnsResourceRecord *rr, bool canonical) {
if (rr->wire_format && rr->wire_format_canonical == canonical)
return 0;
r = dns_packet_append_rr(&packet, rr, &start, &rds);
r = dns_packet_append_rr(&packet, rr, 0, &start, &rds);
if (r < 0)
return r;

8
src/resolve/resolved-dns-scope.c
View File

@ -847,11 +847,11 @@ static int dns_scope_make_conflict_packet(
DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
DNS_PACKET_HEADER(p)->arcount = htobe16(1);
r = dns_packet_append_key(p, rr->key, NULL);
r = dns_packet_append_key(p, rr->key, 0, NULL);
if (r < 0)
return r;
r = dns_packet_append_rr(p, rr, NULL, NULL);
r = dns_packet_append_rr(p, rr, 0, NULL, NULL);
if (r < 0)
return r;
@ -1086,12 +1086,12 @@ void dns_scope_announce(DnsScope *scope) {
answer = dns_answer_new(4);
LIST_FOREACH(addresses, a, scope->link->addresses) {
r = dns_answer_add(answer, a->mdns_address_rr, 0);
r = dns_answer_add(answer, a->mdns_address_rr, 0, DNS_ANSWER_CACHE_FLUSH);
if (r < 0) {
log_debug_errno(r, "Failed to add address RR to answer: %m");
return;
}
r = dns_answer_add(answer, a->mdns_ptr_rr, 0);
r = dns_answer_add(answer, a->mdns_ptr_rr, 0, DNS_ANSWER_CACHE_FLUSH);
if (r < 0) {
log_debug_errno(r, "Failed to add PTR RR to answer: %m");
return;

2
src/resolve/resolved-dns-stub.c
View File

@ -86,7 +86,7 @@ static int dns_stub_make_reply_packet(
continue;
add:
r = dns_packet_append_rr(p, rr, NULL, NULL);
r = dns_packet_append_rr(p, rr, 0, NULL, NULL);
if (r < 0)
return r;

6
src/resolve/resolved-dns-transaction.c
View File

@ -1369,7 +1369,7 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
if (r < 0)
return r;
r = dns_packet_append_key(p, t->key, NULL);
r = dns_packet_append_key(p, t->key, 0, NULL);
if (r < 0)
return r;
@ -1401,7 +1401,7 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
if (qdcount >= UINT16_MAX)
break;
r = dns_packet_append_key(p, other->key, NULL);
r = dns_packet_append_key(p, other->key, 0, NULL);
/*
* If we can't stuff more questions into the packet, just give up.
@ -1470,7 +1470,7 @@ static int dns_transaction_make_packet(DnsTransaction *t) {
if (r < 0)
return r;
r = dns_packet_append_key(p, t->key, NULL);
r = dns_packet_append_key(p, t->key, 0, NULL);
if (r < 0)
return r;