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authorLennart Poettering <lennart@poettering.net>2014-07-23 01:59:36 +0200
committerLennart Poettering <lennart@poettering.net>2014-07-23 02:00:40 +0200
commit934e9b10b4f4bfb48e21883670c7f45b6911fa9b (patch)
treef029033e76fabe439548400c6d7a1c6916f90087 /src/resolve/resolved-dns-query.c
parent7e8e0422aeb16f2a09a40546c61df753d10029b6 (diff)
resolved: most DNS servers can't handle more than one question per packet, hence let's not generate that
Diffstat (limited to 'src/resolve/resolved-dns-query.c')
-rw-r--r--src/resolve/resolved-dns-query.c124
1 files changed, 95 insertions, 29 deletions
diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c
index a56e295f4f..8b4aa3bfd7 100644
--- a/src/resolve/resolved-dns-query.c
+++ b/src/resolve/resolved-dns-query.c
@@ -335,8 +335,9 @@ void dns_query_transaction_process_reply(DnsQueryTransaction *t, DnsPacket *p) {
if (r < 0) {
dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
return;
- } else
- dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, 0);
+ }
+
+ dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, 0);
if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS)
dns_query_transaction_complete(t, DNS_QUERY_SUCCESS);
@@ -575,7 +576,8 @@ static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) {
return 0;
}
-static int dns_query_add_transaction(DnsQuery *q, DnsScope *s) {
+static int dns_query_add_transaction(DnsQuery *q, DnsScope *s, DnsResourceKey *key) {
+ _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
DnsQueryTransaction *t;
int r;
@@ -585,12 +587,23 @@ static int dns_query_add_transaction(DnsQuery *q, DnsScope *s) {
if (r < 0)
return r;
+ if (key) {
+ question = dns_question_new(1);
+ if (!question)
+ return -ENOMEM;
+
+ r = dns_question_add(question, key);
+ if (r < 0)
+ return r;
+ } else
+ question = dns_question_ref(q->question);
+
LIST_FOREACH(transactions_by_scope, t, s->transactions)
- if (dns_question_is_superset(t->question, q->question))
+ if (dns_question_is_superset(t->question, question))
break;
if (!t) {
- r = dns_query_transaction_new(&t, s, q->question);
+ r = dns_query_transaction_new(&t, s, question);
if (r < 0)
return r;
}
@@ -616,6 +629,33 @@ fail:
return r;
}
+static int dns_query_add_transaction_split(DnsQuery *q, DnsScope *s) {
+ int r;
+
+ assert(q);
+ assert(s);
+
+ if (s->protocol == DNS_PROTOCOL_MDNS) {
+ r = dns_query_add_transaction(q, s, NULL);
+ if (r < 0)
+ return r;
+ } else {
+ unsigned i;
+
+ /* On DNS and LLMNR we can only send a single
+ * question per datagram, hence issue multiple
+ * transactions. */
+
+ for (i = 0; i < q->question->n_keys; i++) {
+ r = dns_query_add_transaction(q, s, q->question->keys[i]);
+ if (r < 0)
+ return r;
+ }
+ }
+
+ return 0;
+}
+
int dns_query_go(DnsQuery *q) {
DnsScopeMatch found = DNS_SCOPE_NO;
DnsScope *s, *first = NULL;
@@ -660,7 +700,7 @@ int dns_query_go(DnsQuery *q) {
if (found == DNS_SCOPE_NO)
return -ESRCH;
- r = dns_query_add_transaction(q, first);
+ r = dns_query_add_transaction_split(q, first);
if (r < 0)
return r;
@@ -674,7 +714,7 @@ int dns_query_go(DnsQuery *q) {
if (match != found)
continue;
- r = dns_query_add_transaction(q, s);
+ r = dns_query_add_transaction_split(q, s);
if (r < 0)
return r;
}
@@ -711,8 +751,9 @@ fail:
void dns_query_ready(DnsQuery *q) {
DnsQueryTransaction *t;
DnsQueryState state = DNS_QUERY_NO_SERVERS;
- DnsAnswer *failure_answer = NULL;
- int failure_rcode = 0, failure_ifindex = 0;
+ _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+ int rcode = 0;
+ DnsScope *scope = NULL;
Iterator i;
assert(q);
@@ -728,6 +769,10 @@ void dns_query_ready(DnsQuery *q) {
SET_FOREACH(t, q->transactions, i) {
+ /* If we found a successful answer, ignore all answers from other scopes */
+ if (state == DNS_QUERY_SUCCESS && t->scope != scope)
+ continue;
+
/* One of the transactions is still going on, let's wait for it */
if (t->state == DNS_QUERY_PENDING || t->state == DNS_QUERY_NULL)
return;
@@ -735,34 +780,55 @@ void dns_query_ready(DnsQuery *q) {
/* One of the transactions is successful, let's use
* it, and copy its data out */
if (t->state == DNS_QUERY_SUCCESS) {
+ DnsAnswer *a;
+
if (t->received) {
- q->answer = dns_answer_ref(t->received->answer);
- q->answer_ifindex = t->received->ifindex;
- q->answer_rcode = DNS_PACKET_RCODE(t->received);
+ rcode = DNS_PACKET_RCODE(t->received);
+ a = t->received->answer;
} else {
- q->answer = dns_answer_ref(t->cached);
- q->answer_ifindex = t->scope->link ? t->scope->link->ifindex : 0;
- q->answer_rcode = t->cached_rcode;
+ rcode = t->cached_rcode;
+ a = t->cached;
}
- dns_query_complete(q, DNS_QUERY_SUCCESS);
- return;
+ if (state == DNS_QUERY_SUCCESS) {
+ DnsAnswer *merged;
+
+ merged = dns_answer_merge(answer, a);
+ if (!merged) {
+ dns_query_complete(q, DNS_QUERY_RESOURCES);
+ return;
+ }
+
+ dns_answer_unref(answer);
+ answer = merged;
+ } else {
+ dns_answer_unref(answer);
+ answer = dns_answer_ref(a);
+ }
+
+ scope = t->scope;
+ state = DNS_QUERY_SUCCESS;
+ continue;
}
/* One of the transactions has failed, let's see
* whether we find anything better, but if not, return
- * its response packet */
- if (t->state == DNS_QUERY_FAILURE) {
+ * its response data */
+ if (state != DNS_QUERY_SUCCESS && t->state == DNS_QUERY_FAILURE) {
+ DnsAnswer *a;
+
if (t->received) {
- failure_answer = t->received->answer;
- failure_ifindex = t->received->ifindex;
- failure_rcode = DNS_PACKET_RCODE(t->received);
+ rcode = DNS_PACKET_RCODE(t->received);
+ a = t->received->answer;
} else {
- failure_answer = t->cached;
- failure_ifindex = t->scope->link ? t->scope->link->ifindex : 0;
- failure_rcode = t->cached_rcode;
+ rcode = t->cached_rcode;
+ a = t->cached;
}
+ dns_answer_unref(answer);
+ answer = dns_answer_ref(a);
+
+ scope = t->scope;
state = DNS_QUERY_FAILURE;
continue;
}
@@ -771,10 +837,10 @@ void dns_query_ready(DnsQuery *q) {
state = t->state;
}
- if (state == DNS_QUERY_FAILURE) {
- q->answer = dns_answer_ref(failure_answer);
- q->answer_ifindex = failure_ifindex;
- q->answer_rcode = failure_rcode;
+ if (IN_SET(state, DNS_QUERY_SUCCESS, DNS_QUERY_FAILURE)) {
+ q->answer = dns_answer_ref(answer);
+ q->answer_rcode = rcode;
+ q->answer_ifindex = (scope && scope->link) ? scope->link->ifindex : 0;
}
dns_query_complete(q, state);