diff options
Diffstat (limited to 'src/resolve/resolved-dns-query.c')
| -rw-r--r-- | src/resolve/resolved-dns-query.c | 270 |
1 files changed, 231 insertions, 39 deletions
diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c index dd812150cf..5bd5920254 100644 --- a/src/resolve/resolved-dns-query.c +++ b/src/resolve/resolved-dns-query.c @@ -31,7 +31,12 @@ DnsQueryTransaction* dns_query_transaction_free(DnsQueryTransaction *t) { return NULL; sd_event_source_unref(t->timeout_event_source); - dns_packet_unref(t->packet); + + dns_packet_unref(t->sent); + dns_packet_unref(t->received); + + sd_event_source_unref(t->tcp_event_source); + safe_close(t->tcp_fd); if (t->query) { LIST_REMOVE(transactions_by_query, t->query->transactions, t); @@ -62,6 +67,8 @@ static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, Dns if (!t) return -ENOMEM; + t->tcp_fd = -1; + do random_bytes(&t->id, sizeof(t->id)); while (t->id == 0 || @@ -87,6 +94,14 @@ static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, Dns return 0; } +static void dns_query_transaction_stop(DnsQueryTransaction *t) { + assert(t); + + t->timeout_event_source = sd_event_source_unref(t->timeout_event_source); + t->tcp_event_source = sd_event_source_unref(t->tcp_event_source); + t->tcp_fd = safe_close(t->tcp_fd); +} + static void dns_query_transaction_set_state(DnsQueryTransaction *t, DnsQueryState state) { assert(t); @@ -95,24 +110,179 @@ static void dns_query_transaction_set_state(DnsQueryTransaction *t, DnsQueryStat t->state = state; - if (state != DNS_QUERY_SENT) - t->timeout_event_source = sd_event_source_unref(t->timeout_event_source); + if (state != DNS_QUERY_SENT) { + dns_query_transaction_stop(t); + dns_query_finish(t->query); + } +} + +static int on_tcp_ready(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + DnsQueryTransaction *t = userdata; + int r; + + assert(t); + + if (revents & EPOLLOUT) { + struct iovec iov[2]; + be16_t sz; + ssize_t ss; + + sz = htobe16(t->sent->size); + + iov[0].iov_base = &sz; + iov[0].iov_len = sizeof(sz); + iov[1].iov_base = DNS_PACKET_DATA(t->sent); + iov[1].iov_len = t->sent->size; + + IOVEC_INCREMENT(iov, 2, t->tcp_written); + + ss = writev(fd, iov, 2); + if (ss < 0) { + if (errno != EINTR && errno != EAGAIN) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return -errno; + } + } else + t->tcp_written += ss; + + /* Are we done? If so, disable the event source for EPOLLOUT */ + if (t->tcp_written >= sizeof(sz) + t->sent->size) { + r = sd_event_source_set_io_events(s, EPOLLIN); + if (r < 0) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return r; + } + } + } + + if (revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) { + + if (t->tcp_read < sizeof(t->tcp_read_size)) { + ssize_t ss; + + ss = read(fd, (uint8_t*) &t->tcp_read_size + t->tcp_read, sizeof(t->tcp_read_size) - t->tcp_read); + if (ss < 0) { + if (errno != EINTR && errno != EAGAIN) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return -errno; + } + } else if (ss == 0) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return -EIO; + } else + t->tcp_read += ss; + } + + if (t->tcp_read >= sizeof(t->tcp_read_size)) { + + if (be16toh(t->tcp_read_size) < DNS_PACKET_HEADER_SIZE) { + dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY); + return -EBADMSG; + } + + if (t->tcp_read < sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) { + ssize_t ss; + + if (!t->received) { + r = dns_packet_new(&t->received, be16toh(t->tcp_read_size)); + if (r < 0) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return r; + } + } + + ss = read(fd, + (uint8_t*) DNS_PACKET_DATA(t->received) + t->tcp_read - sizeof(t->tcp_read_size), + sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size) - t->tcp_read); + if (ss < 0) { + if (errno != EINTR && errno != EAGAIN) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return -errno; + } + } else if (ss == 0) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return -EIO; + } else + t->tcp_read += ss; + } + + if (t->tcp_read >= sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) { + t->received->size = be16toh(t->tcp_read_size); + dns_query_transaction_reply(t, t->received); + return 0; + } + } + } + + return 0; +} + +static int dns_query_transaction_start_tcp(DnsQueryTransaction *t) { + int r; + + assert(t); + + if (t->tcp_fd >= 0) + return 0; + + t->tcp_written = 0; + t->tcp_read = 0; + t->received = dns_packet_unref(t->received); + + t->tcp_fd = dns_scope_tcp_socket(t->scope); + if (t->tcp_fd < 0) + return t->tcp_fd; + + r = sd_event_add_io(t->query->manager->event, &t->tcp_event_source, t->tcp_fd, EPOLLIN|EPOLLOUT, on_tcp_ready, t); + if (r < 0) { + t->tcp_fd = safe_close(t->tcp_fd); + return r; + } - dns_query_finish(t->query); + return 0; } -int dns_query_transaction_reply(DnsQueryTransaction *t, DnsPacket *p) { +void dns_query_transaction_reply(DnsQueryTransaction *t, DnsPacket *p) { + int r; + assert(t); assert(p); - t->packet = dns_packet_ref(p); + if (t->state != DNS_QUERY_SENT) + return; + + if (t->received != p) { + dns_packet_unref(t->received); + t->received = dns_packet_ref(p); + } + + if (t->tcp_fd >= 0) { + if (DNS_PACKET_TC(p)) { + /* Truncated via TCP? Somebody must be fucking with us */ + dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY); + return; + } + + if (DNS_PACKET_ID(p) != t->id) { + /* Not the reply to our query? Somebody must be fucking with us */ + dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY); + return; + } + } + + if (DNS_PACKET_TC(p)) { + /* Response was truncated, let's try again with good old TCP */ + r = dns_query_transaction_start_tcp(t); + if (r < 0) { + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + return; + } + } if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS) dns_query_transaction_set_state(t, DNS_QUERY_SUCCESS); else dns_query_transaction_set_state(t, DNS_QUERY_FAILURE); - - return 0; } static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) { @@ -127,26 +297,20 @@ static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdat r = dns_query_transaction_start(t); if (r < 0) - dns_query_transaction_set_state(t, DNS_QUERY_FAILURE); + dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); return 0; } -int dns_query_transaction_start(DnsQueryTransaction *t) { +static int dns_query_make_packet(DnsQueryTransaction *t) { _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; unsigned n; int r; assert(t); - t->timeout_event_source = sd_event_source_unref(t->timeout_event_source); - - if (t->n_attempts >= ATTEMPTS_MAX) { - dns_query_transaction_set_state(t, DNS_QUERY_ATTEMPTS_MAX); + if (t->sent) return 0; - } - - t->n_attempts++; r = dns_packet_new_query(&p, 0); if (r < 0) @@ -161,7 +325,38 @@ int dns_query_transaction_start(DnsQueryTransaction *t) { DNS_PACKET_HEADER(p)->qdcount = htobe16(t->query->n_keys); DNS_PACKET_HEADER(p)->id = t->id; - r = dns_scope_send(t->scope, p); + t->sent = p; + p = NULL; + + return 0; +} + +int dns_query_transaction_start(DnsQueryTransaction *t) { + int r; + + assert(t); + + dns_query_transaction_stop(t); + + if (t->n_attempts >= ATTEMPTS_MAX) { + dns_query_transaction_set_state(t, DNS_QUERY_ATTEMPTS_MAX); + return 0; + } + t->n_attempts++; + + r = dns_query_make_packet(t); + if (r < 0) + return r; + + /* Try via UDP, and if that fails due to large size try via TCP */ + r = dns_scope_send(t->scope, t->sent); + if (r == -EMSGSIZE) + r = dns_query_transaction_start_tcp(t); + + if (r == -ESRCH) { + dns_query_transaction_set_state(t, DNS_QUERY_NO_SERVERS); + return 0; + } if (r < 0) { /* Couldn't send? Try immediately again, with a new server */ dns_scope_next_dns_server(t->scope); @@ -169,18 +364,12 @@ int dns_query_transaction_start(DnsQueryTransaction *t) { return dns_query_transaction_start(t); } - if (r > 0) { - int q; - - q = sd_event_add_time(t->query->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC, 0, on_transaction_timeout, t); - if (q < 0) - return q; - - dns_query_transaction_set_state(t, DNS_QUERY_SENT); - } else - dns_query_transaction_set_state(t, DNS_QUERY_SKIPPED); + r = sd_event_add_time(t->query->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC, 0, on_transaction_timeout, t); + if (r < 0) + return r; - return r; + dns_query_transaction_set_state(t, DNS_QUERY_SENT); + return 1; } DnsQuery *dns_query_free(DnsQuery *q) { @@ -190,7 +379,7 @@ DnsQuery *dns_query_free(DnsQuery *q) { return NULL; sd_bus_message_unref(q->request); - dns_packet_unref(q->packet); + dns_packet_unref(q->received); sd_event_source_unref(q->timeout_event_source); while (q->transactions) @@ -367,8 +556,8 @@ fail: void dns_query_finish(DnsQuery *q) { DnsQueryTransaction *t; - DnsQueryState state = DNS_QUERY_SKIPPED; - uint16_t rcode = 0; + DnsQueryState state = DNS_QUERY_NO_SERVERS; + DnsPacket *received = NULL; assert(q); @@ -381,25 +570,28 @@ void dns_query_finish(DnsQuery *q) { if (t->state == DNS_QUERY_SENT || t->state == DNS_QUERY_NULL) return; - /* One of the transactions is sucecssful, let's use it */ + /* One of the transactions is successful, let's use it */ if (t->state == DNS_QUERY_SUCCESS) { - q->packet = dns_packet_ref(t->packet); + q->received = dns_packet_ref(t->received); dns_query_set_state(q, DNS_QUERY_SUCCESS); return; } + /* 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) { + received = t->received; state = DNS_QUERY_FAILURE; + continue; + } - if (rcode == 0 && t->packet) - rcode = DNS_PACKET_RCODE(t->packet); - - } else if (state == DNS_QUERY_SKIPPED && t->state != DNS_QUERY_SKIPPED) + if (state == DNS_QUERY_NO_SERVERS && t->state != DNS_QUERY_NO_SERVERS) state = t->state; } if (state == DNS_QUERY_FAILURE) - q->rcode = rcode; + q->received = dns_packet_ref(received); dns_query_set_state(q, state); } |