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Revert "resolve: mDNS transaction max attempts fix"

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This reverts commit 127b26f3d8.

The commit made mDNS queries quite unstable.
Note that, RFC 6762 does not explicitly prohibit to send a request
multiple times.
This commit is contained in:
Yu Watanabe 2022-07-04 05:24:52 +09:00
parent d50a58e725
commit c3dbb13288
2 changed files with 8 additions and 28 deletions
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2
src/resolve/resolved-dns-transaction.c
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@ -1622,7 +1622,7 @@ static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
return 0;
}
if (t->n_attempts >= dns_transaction_attempts_max(t->scope->protocol, t->probing)) {
if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) {
DnsTransactionState result;
if (t->scope->protocol == DNS_PROTOCOL_LLMNR)

34
src/resolve/resolved-dns-transaction.h
View File

@ -214,31 +214,11 @@ DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
/* Maximum attempts to send MDNS requests is one except for probe requests, see RFC 6762 Section 8.1
* RFC 6762 differentiates between normal (single-shot/continuous) and probe requests.
* It therefore makes sense to attempt each normal query only once with no retries.
* Otherwise we'd be sending out three attempts for even a normal query. */
#define MDNS_TRANSACTION_ATTEMPTS_MAX 1
/* Maximum attempts to send MDNS requests, see RFC 6762 Section 8.1 */
#define MDNS_TRANSACTION_ATTEMPTS_MAX 3
#define MDNS_PROBE_TRANSACTION_ATTEMPTS_MAX 3
static inline unsigned dns_transaction_attempts_max(DnsProtocol p, bool probing) {
switch (p) {
case DNS_PROTOCOL_LLMNR:
return LLMNR_TRANSACTION_ATTEMPTS_MAX;
case DNS_PROTOCOL_MDNS:
if (probing)
return MDNS_PROBE_TRANSACTION_ATTEMPTS_MAX;
else
return MDNS_TRANSACTION_ATTEMPTS_MAX;
case DNS_PROTOCOL_DNS:
return DNS_TRANSACTION_ATTEMPTS_MAX;
default:
return 0;
}
}
#define TRANSACTION_ATTEMPTS_MAX(p) (((p) == DNS_PROTOCOL_LLMNR) ? \
LLMNR_TRANSACTION_ATTEMPTS_MAX : \
(((p) == DNS_PROTOCOL_MDNS) ? \
MDNS_TRANSACTION_ATTEMPTS_MAX : \
DNS_TRANSACTION_ATTEMPTS_MAX))