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resolved: keep stub stream connections up for as long as client wants

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This enables pipelining of queries from clients to our stub server.

Fixes: #11332
This commit is contained in:
Lennart Poettering 2019-01-21 19:44:30 +01:00
parent f447d9e376
commit b412af57a3
4 changed files with 38 additions and 41 deletions
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6
src/resolve/resolved-dns-query.c
View File

@ -387,10 +387,8 @@ DnsQuery *dns_query_free(DnsQuery *q) {
if (q->request_dns_stream) {
/* Detach the stream from our query, in case something else keeps a reference to it. */
q->request_dns_stream->complete = NULL;
q->request_dns_stream->on_packet = NULL;
q->request_dns_stream->query = NULL;
dns_stream_unref(q->request_dns_stream);
(void) set_remove(q->request_dns_stream->queries, q);
q->request_dns_stream = dns_stream_unref(q->request_dns_stream);
}
free(q->request_address_string);

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

@ -11,6 +11,8 @@
#define DNS_STREAM_TIMEOUT_USEC (10 * USEC_PER_SEC)
#define DNS_STREAMS_MAX 128
#define DNS_QUERIES_PER_STREAM 32
static void dns_stream_stop(DnsStream *s) {
assert(s);
@ -36,7 +38,11 @@ static int dns_stream_update_io(DnsStream *s) {
s->n_written = 0;
f |= EPOLLOUT;
}
if (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size)
/* Let's read a packet if we haven't queued any yet. Except if we already hit a limit of parallel
* queries for this connection. */
if ((!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size) &&
set_size(s->queries) < DNS_QUERIES_PER_STREAM)
f |= EPOLLIN;
#if ENABLE_DNS_OVER_TLS

2
src/resolve/resolved-dns-stream.h
View File

@ -68,7 +68,7 @@ struct DnsStream {
LIST_HEAD(DnsTransaction, transactions); /* when used by the transaction logic */
DnsServer *server; /* when used by the transaction logic */
DnsQuery *query; /* when used by the DNS stub logic */
Set *queries; /* when used by the DNS stub logic */
/* used when DNS-over-TLS is enabled */
bool encrypted:1;

63
src/resolve/resolved-dns-stub.c
View File

@ -126,14 +126,6 @@ static int dns_stub_finish_reply_packet(
return 0;
}
static void dns_stub_detach_stream(DnsStream *s) {
assert(s);
s->complete = NULL;
s->on_packet = NULL;
s->query = NULL;
}
static int dns_stub_send(Manager *m, DnsStream *s, DnsPacket *p, DnsPacket *reply) {
int r;
@ -257,27 +249,27 @@ static void dns_stub_query_complete(DnsQuery *q) {
assert_not_reached("Impossible state");
}
/* If there's a packet to write set, let's leave the stream around */
if (q->request_dns_stream && DNS_STREAM_QUEUED(q->request_dns_stream)) {
/* Detach the stream from our query (make it an orphan), but do not drop the reference to it. The
* default completion action of the stream will drop the reference. */
dns_stub_detach_stream(q->request_dns_stream);
q->request_dns_stream = NULL;
}
dns_query_free(q);
}
static int dns_stub_stream_complete(DnsStream *s, int error) {
assert(s);
log_debug_errno(error, "DNS TCP connection terminated, destroying query: %m");
log_debug_errno(error, "DNS TCP connection terminated, destroying queries: %m");
assert(s->query);
dns_query_free(s->query);
for (;;) {
DnsQuery *q;
q = set_first(s->queries);
if (!q)
break;
dns_query_free(q);
}
/* This drops the implicit ref we keep around since it was allocated, as incoming stub connections
* should be kept as long as the client wants to. */
dns_stream_unref(s);
return 0;
}
@ -289,8 +281,6 @@ static void dns_stub_process_query(Manager *m, DnsStream *s, DnsPacket *p) {
assert(p);
assert(p->protocol == DNS_PROTOCOL_DNS);
/* Takes ownership of the *s stream object */
if (in_addr_is_localhost(p->family, &p->sender) <= 0 ||
in_addr_is_localhost(p->family, &p->destination) <= 0) {
log_error("Got packet on unexpected IP range, refusing.");
@ -351,9 +341,19 @@ static void dns_stub_process_query(Manager *m, DnsStream *s, DnsPacket *p) {
q->complete = dns_stub_query_complete;
if (s) {
s->on_packet = NULL;
s->complete = dns_stub_stream_complete;
s->query = q;
/* Remember which queries belong to this stream, so that we can cancel them when the stream
* is disconnected early */
r = set_ensure_allocated(&s->queries, &trivial_hash_ops);
if (r < 0) {
log_oom();
goto fail;
}
if (set_put(s->queries, q) < 0) {
log_oom();
goto fail;
}
}
r = dns_query_go(q);
@ -367,9 +367,6 @@ static void dns_stub_process_query(Manager *m, DnsStream *s, DnsPacket *p) {
return;
fail:
if (s && DNS_STREAM_QUEUED(s))
dns_stub_detach_stream(s);
dns_query_free(q);
}
@ -451,10 +448,6 @@ static int on_dns_stub_stream_packet(DnsStream *s) {
} else
log_debug("Invalid DNS stub TCP packet, ignoring.");
/* Drop the reference to the stream. Either a query was created and added its own reference to the stream now,
* or that didn't happen in which case we want to free the stream */
dns_stream_unref(s);
return 0;
}
@ -478,9 +471,9 @@ static int on_dns_stub_stream(sd_event_source *s, int fd, uint32_t revents, void
}
stream->on_packet = on_dns_stub_stream_packet;
stream->complete = dns_stub_stream_complete;
/* We let the reference to the stream dangling here, it will either be dropped by the default "complete" action
* of the stream, or by our packet callback, or when the manager is shut down. */
/* We let the reference to the stream dangle here, it will be dropped later by the complete callback. */
return 0;
}