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/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#include "lib/selection_forward.h"
#include "lib/resolve.h"
#define VERBOSE_MSG(qry, ...) kr_log_q((qry), SELECTION, __VA_ARGS__)
#define FORWARDING_TIMEOUT 2000
/* TODO: well, this is a bit hard; maybe we'd better have a different approach
* for estimating DEAD-ness for forwarding.
* Even ACKs on connections might be useful here. */
static_assert(FORWARDING_TIMEOUT >= KR_NS_TIMEOUT_MIN_DEAD_TIMEOUT,
"Bad combination of NS selection limits.");
struct forward_local_state {
kr_sockaddr_array_t *targets;
struct address_state *addr_states;
/** Index of last choice in the targets array, used for error reporting. */
size_t last_choice_index;
};
void forward_local_state_alloc(struct knot_mm *mm, void **local_state,
struct kr_request *req)
{
kr_require(req->selection_context.forwarding_targets.at);
*local_state = mm_calloc(mm, 1, sizeof(struct forward_local_state));
struct forward_local_state *forward_state = *local_state;
forward_state->targets = &req->selection_context.forwarding_targets;
forward_state->addr_states = mm_calloc(mm, forward_state->targets->len,
sizeof(struct address_state));
}
void forward_choose_transport(struct kr_query *qry,
struct kr_transport **transport)
{
struct forward_local_state *local_state =
qry->server_selection.local_state->private;
struct choice choices[local_state->targets->len];
int valid = 0;
for (int i = 0; i < local_state->targets->len; i++) {
union kr_sockaddr *address = &local_state->targets->at[i];
size_t addr_len;
uint16_t port;
switch (address->ip.sa_family) {
case AF_INET:
port = ntohs(address->ip4.sin_port);
addr_len = sizeof(struct in_addr);
break;
case AF_INET6:
port = ntohs(address->ip6.sin6_port);
addr_len = sizeof(struct in6_addr);
break;
default:
kr_assert(false);
*transport = NULL;
goto cleanup;
}
struct address_state *addr_state = &local_state->addr_states[i];
addr_state->ns_name = (knot_dname_t *)"";
update_address_state(addr_state, address, addr_len, qry);
if (addr_state->generation == -1 || addr_state->broken) {
continue;
}
addr_state->choice_array_index = i;
choices[valid++] = (struct choice){
.address = *address,
.address_len = addr_len,
.address_state = addr_state,
.port = port,
};
}
bool tcp = qry->flags.TCP || qry->server_selection.local_state->truncated;
*transport =
select_transport(choices, valid, NULL, 0,
qry->server_selection.local_state->timeouts,
&qry->request->pool, tcp,
&local_state->last_choice_index);
if (*transport) {
/* Set static timeout for forwarding; there is no point in this
* being dynamic since the RTT of a packet to forwarding target
* says nothing about the network RTT of said target, since
* it is doing resolution upstream. */
(*transport)->timeout = FORWARDING_TIMEOUT;
/* Try to avoid TCP in STUB case. It seems better for common use cases. */
if (qry->flags.STUB && !tcp && (*transport)->protocol == KR_TRANSPORT_TCP)
(*transport)->protocol = KR_TRANSPORT_UDP;
/* We need to propagate this to flags since it's used in other
* parts of the resolver (e.g. logging and stats). */
qry->flags.TCP = (*transport)->protocol == KR_TRANSPORT_TCP
|| (*transport)->protocol == KR_TRANSPORT_TLS;
}
cleanup:
kr_cache_commit(&qry->request->ctx->cache);
}
void forward_error(struct kr_query *qry, const struct kr_transport *transport,
enum kr_selection_error sel_error)
{
if (!qry->server_selection.initialized) {
return;
}
struct forward_local_state *local_state =
qry->server_selection.local_state->private;
struct address_state *addr_state =
&local_state->addr_states[local_state->last_choice_index];
error(qry, addr_state, transport, sel_error);
}
void forward_update_rtt(struct kr_query *qry,
const struct kr_transport *transport, unsigned rtt)
{
if (!qry->server_selection.initialized) {
return;
}
if (!transport) {
return;
}
struct forward_local_state *local_state =
qry->server_selection.local_state->private;
struct address_state *addr_state =
&local_state->addr_states[local_state->last_choice_index];
update_rtt(qry, addr_state, transport, rtt);
}
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