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resolved: lengthen timeout for TCP transactions

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When we are doing a TCP transaction the kernel will automatically resend
all packets for us, there's no need to do that ourselves. Hence:
increase the timeout for TCP transactions substantially, to give the
kernel enough time to connect to the peer, without interrupting it when
we become impatient.
This commit is contained in:
Lennart Poettering 2017-02-15 18:24:46 +01:00
parent 97277567b8
commit dc349f5f7a
1 changed files with 10 additions and 1 deletions
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11
src/resolve/resolved-dns-transaction.c
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@ -31,6 +31,7 @@
#include "string-table.h"
#define TRANSACTIONS_MAX 4096
#define TRANSACTION_TCP_TIMEOUT_USEC (10U*USEC_PER_SEC)
static void dns_transaction_reset_answer(DnsTransaction *t) {
assert(t);
@ -1212,9 +1213,17 @@ static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
assert(t);
assert(t->scope);
switch (t->scope->protocol) {
case DNS_PROTOCOL_DNS:
/* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
* resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
* needlessly. */
if (t->stream)
return TRANSACTION_TCP_TIMEOUT_USEC;
assert(t->server);
return t->server->resend_timeout;
@ -1579,7 +1588,7 @@ int dns_transaction_go(DnsTransaction *t) {
r = dns_transaction_emit_udp(t);
if (r == -EMSGSIZE)
log_debug("Sending query via TCP since it is too large.");
if (r == -EAGAIN)
else if (r == -EAGAIN)
log_debug("Sending query via TCP since server doesn't support UDP.");
if (r == -EMSGSIZE || r == -EAGAIN)
r = dns_transaction_open_tcp(t);