diff options
| -rw-r--r-- | src/resolve/resolved-dns-transaction.c | 41 |
1 files changed, 35 insertions, 6 deletions
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c index d4ccc86819..b2e1e60a58 100644 --- a/src/resolve/resolved-dns-transaction.c +++ b/src/resolve/resolved-dns-transaction.c @@ -137,6 +137,22 @@ bool dns_transaction_gc(DnsTransaction *t) { return true; } +static uint16_t pick_new_id(Manager *m) { + uint16_t new_id; + + /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the number of + * transactions, and it's much lower than the space of IDs. */ + + assert_cc(TRANSACTIONS_MAX < 0xFFFF); + + do + random_bytes(&new_id, sizeof(new_id)); + while (new_id == 0 || + hashmap_get(m->dns_transactions, UINT_TO_PTR(new_id))); + + return new_id; +} + int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) { _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL; int r; @@ -177,11 +193,7 @@ int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) t->key = dns_resource_key_ref(key); t->current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID; - /* Find a fresh, unused transaction id */ - do - random_bytes(&t->id, sizeof(t->id)); - while (t->id == 0 || - hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(t->id))); + t->id = pick_new_id(s->manager); r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t); if (r < 0) { @@ -208,6 +220,22 @@ int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) return 0; } +static void dns_transaction_shuffle_id(DnsTransaction *t) { + uint16_t new_id; + assert(t); + + /* Pick a new ID for this transaction. */ + + new_id = pick_new_id(t->scope->manager); + assert_se(hashmap_remove_and_put(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id), UINT_TO_PTR(new_id), t) >= 0); + + log_debug("Transaction %" PRIu16 " is now %" PRIu16 ".", t->id, new_id); + t->id = new_id; + + /* Make sure we generate a new packet with the new ID */ + t->sent = dns_packet_unref(t->sent); +} + static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) { _cleanup_free_ char *pretty = NULL; DnsZoneItem *z; @@ -382,7 +410,8 @@ static int dns_transaction_maybe_restart(DnsTransaction *t) { OPT RR or DO bit. One of these cases is documented here, for example: https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */ - log_debug("Server feature level is now lower than when we began our transaction. Restarting."); + log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID."); + dns_transaction_shuffle_id(t); return dns_transaction_go(t); } |