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Merge pull request #22274 from yuwata/resolve-comment

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resolve: cleanups for on_stream_io()
This commit is contained in:
Luca Boccassi
2022-01-31 13:56:04 +00:00
committed by GitHub
parent 9d6d4c305a a5e2a488e8
commit 06d4d83fa7
6 changed files with 81 additions and 67 deletions
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84
src/resolve/resolved-dns-stream.c
View File

@@ -281,6 +281,29 @@ static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) {
return dns_stream_complete(s, ETIMEDOUT);
}
static DnsPacket *dns_stream_take_read_packet(DnsStream *s) {
assert(s);
/* Note, dns_stream_update() should be called after this is called. When this is called, the
* stream may be already full and the EPOLLIN flag is dropped from the stream IO event source.
* Even this makes a room to read in the stream, this does not call dns_stream_update(), hence
* EPOLLIN flag is not set automatically. So, to read further packets from the stream,
* dns_stream_update() must be called explicitly. Currently, this is only called from
* on_stream_io_impl(), and there dns_stream_update() is called. */
if (!s->read_packet)
return NULL;
if (s->n_read < sizeof(s->read_size))
return NULL;
if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size))
return NULL;
s->n_read = 0;
return TAKE_PTR(s->read_packet);
}
static int on_stream_io_impl(DnsStream *s, uint32_t revents) {
bool progressed = false;
int r;
@@ -411,31 +434,37 @@ static int on_stream_io_impl(DnsStream *s, uint32_t revents) {
s->n_read += ss;
}
/* Are we done? If so, disable the event source for EPOLLIN */
if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) {
/* If there's a packet handler
* installed, call that. Note that
* this is optional... */
if (s->on_packet) {
r = s->on_packet(s);
if (r < 0)
return r;
}
/* Are we done? If so, call the packet handler and re-enable EPOLLIN for the
* event source if necessary. */
_cleanup_(dns_packet_unrefp) DnsPacket *p = dns_stream_take_read_packet(s);
if (p) {
assert(s->on_packet);
r = s->on_packet(s, p);
if (r < 0)
return r;
r = dns_stream_update_io(s);
if (r < 0)
return dns_stream_complete(s, -r);
s->packet_received = true;
}
}
}
/* Call "complete" callback if finished reading and writing one packet, and there's nothing else left
* to write. */
if (s->type == DNS_STREAM_LLMNR_SEND &&
(s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) &&
ordered_set_isempty(s->write_queue) &&
(s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size))
return dns_stream_complete(s, 0);
if (s->type == DNS_STREAM_LLMNR_SEND && s->packet_received) {
uint32_t events;
/* Complete the stream if finished reading and writing one packet, and there's nothing
* else left to write. */
r = sd_event_source_get_io_events(s->io_event_source, &events);
if (r < 0)
return r;
if (!FLAGS_SET(events, EPOLLOUT))
return dns_stream_complete(s, 0);
}
/* If we did something, let's restart the timeout event source */
if (progressed && s->timeout_event_source) {
@@ -523,6 +552,8 @@ int dns_stream_new(
DnsProtocol protocol,
int fd,
const union sockaddr_union *tfo_address,
int (on_packet)(DnsStream*, DnsPacket*),
int (complete)(DnsStream*, int), /* optional */
usec_t connect_timeout_usec) {
_cleanup_(dns_stream_unrefp) DnsStream *s = NULL;
@@ -535,6 +566,7 @@ int dns_stream_new(
assert(protocol >= 0);
assert(protocol < _DNS_PROTOCOL_MAX);
assert(fd >= 0);
assert(on_packet);
if (m->n_dns_streams[type] > DNS_STREAMS_MAX)
return -EBUSY;
@@ -576,6 +608,8 @@ int dns_stream_new(
s->manager = m;
s->fd = fd;
s->on_packet = on_packet;
s->complete = complete;
if (tfo_address) {
s->tfo_address = *tfo_address;
@@ -602,22 +636,6 @@ int dns_stream_write_packet(DnsStream *s, DnsPacket *p) {
return dns_stream_update_io(s);
}
DnsPacket *dns_stream_take_read_packet(DnsStream *s) {
assert(s);
if (!s->read_packet)
return NULL;
if (s->n_read < sizeof(s->read_size))
return NULL;
if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size))
return NULL;
s->n_read = 0;
return TAKE_PTR(s->read_packet);
}
void dns_stream_detach(DnsStream *s) {
assert(s);

16
src/resolve/resolved-dns-stream.h
View File

@@ -60,6 +60,7 @@ struct DnsStream {
int ifindex;
uint32_t ttl;
bool identified;
bool packet_received; /* At least one packet is received. Used by LLMNR. */
/* only when using TCP fast open */
union sockaddr_union tfo_address;
@@ -78,7 +79,7 @@ struct DnsStream {
size_t n_written, n_read;
OrderedSet *write_queue;
int (*on_packet)(DnsStream *s);
int (*on_packet)(DnsStream *s, DnsPacket *p);
int (*complete)(DnsStream *s, int error);
LIST_HEAD(DnsTransaction, transactions); /* when used by the transaction logic */
@@ -93,7 +94,16 @@ struct DnsStream {
LIST_FIELDS(DnsStream, streams);
};
int dns_stream_new(Manager *m, DnsStream **s, DnsStreamType type, DnsProtocol protocol, int fd, const union sockaddr_union *tfo_address, usec_t timeout);
int dns_stream_new(
Manager *m,
DnsStream **ret,
DnsStreamType type,
DnsProtocol protocol,
int fd,
const union sockaddr_union *tfo_address,
int (on_packet)(DnsStream*, DnsPacket*),
int (complete)(DnsStream*, int), /* optional */
usec_t connect_timeout_usec);
#if ENABLE_DNS_OVER_TLS
int dns_stream_connect_tls(DnsStream *s, void *tls_session);
#endif
@@ -114,6 +124,4 @@ static inline bool DNS_STREAM_QUEUED(DnsStream *s) {
return !!s->write_packet;
}
DnsPacket *dns_stream_take_read_packet(DnsStream *s);
void dns_stream_detach(DnsStream *s);

12
src/resolve/resolved-dns-stub.c
View File

@@ -1044,12 +1044,9 @@ static int on_dns_stub_packet_extra(sd_event_source *s, int fd, uint32_t revents
return on_dns_stub_packet_internal(s, fd, revents, l->manager, l);
}
static int on_dns_stub_stream_packet(DnsStream *s) {
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
static int on_dns_stub_stream_packet(DnsStream *s, DnsPacket *p) {
assert(s);
p = dns_stream_take_read_packet(s);
assert(s->manager);
assert(p);
if (dns_packet_validate_query(p) > 0) {
@@ -1074,15 +1071,14 @@ static int on_dns_stub_stream_internal(sd_event_source *s, int fd, uint32_t reve
return -errno;
}
r = dns_stream_new(m, &stream, DNS_STREAM_STUB, DNS_PROTOCOL_DNS, cfd, NULL, DNS_STREAM_STUB_TIMEOUT_USEC);
r = dns_stream_new(m, &stream, DNS_STREAM_STUB, DNS_PROTOCOL_DNS, cfd, NULL,
on_dns_stub_stream_packet, dns_stub_stream_complete, DNS_STREAM_STUB_TIMEOUT_USEC);
if (r < 0) {
safe_close(cfd);
return r;
}
stream->stub_listener_extra = l;
stream->on_packet = on_dns_stub_stream_packet;
stream->complete = dns_stub_stream_complete;
/* We let the reference to the stream dangle here, it will be dropped later by the complete callback. */

14
src/resolve/resolved-dns-transaction.c
View File

@@ -644,14 +644,12 @@ static int on_stream_complete(DnsStream *s, int error) {
return 0;
}
static int on_stream_packet(DnsStream *s) {
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
static int on_stream_packet(DnsStream *s, DnsPacket *p) {
DnsTransaction *t;
assert(s);
/* Take ownership of packet to be able to receive new packets */
assert_se(p = dns_stream_take_read_packet(s));
assert(s->manager);
assert(p);
t = hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
if (t && t->stream == s) /* Validate that the stream we got this on actually is the stream the
@@ -754,7 +752,8 @@ static int dns_transaction_emit_tcp(DnsTransaction *t) {
if (fd < 0)
return fd;
r = dns_stream_new(t->scope->manager, &s, type, t->scope->protocol, fd, &sa, stream_timeout_usec);
r = dns_stream_new(t->scope->manager, &s, type, t->scope->protocol, fd, &sa,
on_stream_packet, on_stream_complete, stream_timeout_usec);
if (r < 0)
return r;
@@ -777,9 +776,6 @@ static int dns_transaction_emit_tcp(DnsTransaction *t) {
t->server->stream = dns_stream_ref(s);
}
s->complete = on_stream_complete;
s->on_packet = on_stream_packet;
/* The interface index is difficult to determine if we are
* connecting to the local host, hence fill this in right away
* instead of determining it from the socket */

14
src/resolve/resolved-llmnr.c
View File

@@ -277,13 +277,11 @@ int manager_llmnr_ipv6_udp_fd(Manager *m) {
return m->llmnr_ipv6_udp_fd = TAKE_FD(s);
}
static int on_llmnr_stream_packet(DnsStream *s) {
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
static int on_llmnr_stream_packet(DnsStream *s, DnsPacket *p) {
DnsScope *scope;
assert(s);
p = dns_stream_take_read_packet(s);
assert(s->manager);
assert(p);
scope = manager_find_scope(s->manager, p);
@@ -296,7 +294,6 @@ static int on_llmnr_stream_packet(DnsStream *s) {
} else
log_debug("Invalid LLMNR TCP packet, ignoring.");
dns_stream_unref(s);
return 0;
}
@@ -313,15 +310,14 @@ static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *u
return -errno;
}
r = dns_stream_new(m, &stream, DNS_STREAM_LLMNR_RECV, DNS_PROTOCOL_LLMNR, cfd, NULL, DNS_STREAM_DEFAULT_TIMEOUT_USEC);
/* We don't configure a "complete" handler here, we rely on the default handler, thus freeing it */
r = dns_stream_new(m, &stream, DNS_STREAM_LLMNR_RECV, DNS_PROTOCOL_LLMNR, cfd, NULL,
on_llmnr_stream_packet, NULL, DNS_STREAM_DEFAULT_TIMEOUT_USEC);
if (r < 0) {
safe_close(cfd);
return r;
}
stream->on_packet = on_llmnr_stream_packet;
/* We don't configure a "complete" handler here, we rely on the default handler than simply drops the
* reference to the stream, thus freeing it */
return 0;
}

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

@@ -194,9 +194,9 @@ static const size_t MAX_RECEIVED_PACKETS = 2;
static DnsPacket *received_packets[2] = {};
static size_t n_received_packets = 0;
static int on_stream_packet(DnsStream *stream) {
static int on_stream_packet(DnsStream *stream, DnsPacket *p) {
assert_se(n_received_packets < MAX_RECEIVED_PACKETS);
assert_se(received_packets[n_received_packets++] = dns_stream_take_read_packet(stream));
assert_se(received_packets[n_received_packets++] = dns_packet_ref(p));
return 0;
}
@@ -253,8 +253,8 @@ static void test_dns_stream(bool tls) {
/* Initialize DNS stream */
assert_se(dns_stream_new(&manager, &stream, DNS_STREAM_LOOKUP, DNS_PROTOCOL_DNS,
TAKE_FD(clientfd), NULL, DNS_STREAM_DEFAULT_TIMEOUT_USEC) >= 0);
stream->on_packet = on_stream_packet;
TAKE_FD(clientfd), NULL, on_stream_packet, NULL,
DNS_STREAM_DEFAULT_TIMEOUT_USEC) >= 0);
#if ENABLE_DNS_OVER_TLS
if (tls) {
DnsServer server = {