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/*
* ngtcp2
*
* Copyright (c) 2022 ngtcp2 contributors
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "ngtcp2_pmtud.h"
#include <assert.h>
#include "ngtcp2_mem.h"
#include "ngtcp2_macro.h"
/* NGTCP2_PMTUD_PROBE_NUM_MAX is the maximum number of packets sent
for each probe. */
#define NGTCP2_PMTUD_PROBE_NUM_MAX 3
static size_t mtu_probes[] = {
1454 - 48, /* The well known MTU used by a domestic optic fiber
service in Japan. */
1390 - 48, /* Typical Tunneled MTU */
1280 - 48, /* IPv6 minimum MTU */
1492 - 48, /* PPPoE */
};
#define NGTCP2_MTU_PROBESLEN ngtcp2_arraylen(mtu_probes)
int ngtcp2_pmtud_new(ngtcp2_pmtud **ppmtud, size_t max_udp_payload_size,
size_t hard_max_udp_payload_size, int64_t tx_pkt_num,
const ngtcp2_mem *mem) {
ngtcp2_pmtud *pmtud = ngtcp2_mem_malloc(mem, sizeof(ngtcp2_pmtud));
if (pmtud == NULL) {
return NGTCP2_ERR_NOMEM;
}
pmtud->mem = mem;
pmtud->mtu_idx = 0;
pmtud->num_pkts_sent = 0;
pmtud->expiry = UINT64_MAX;
pmtud->tx_pkt_num = tx_pkt_num;
pmtud->max_udp_payload_size = max_udp_payload_size;
pmtud->hard_max_udp_payload_size = hard_max_udp_payload_size;
pmtud->min_fail_udp_payload_size = SIZE_MAX;
for (; pmtud->mtu_idx < NGTCP2_MTU_PROBESLEN; ++pmtud->mtu_idx) {
if (mtu_probes[pmtud->mtu_idx] > pmtud->hard_max_udp_payload_size) {
continue;
}
if (mtu_probes[pmtud->mtu_idx] > pmtud->max_udp_payload_size) {
break;
}
}
*ppmtud = pmtud;
return 0;
}
void ngtcp2_pmtud_del(ngtcp2_pmtud *pmtud) {
if (!pmtud) {
return;
}
ngtcp2_mem_free(pmtud->mem, pmtud);
}
size_t ngtcp2_pmtud_probelen(ngtcp2_pmtud *pmtud) {
assert(pmtud->mtu_idx < NGTCP2_MTU_PROBESLEN);
return mtu_probes[pmtud->mtu_idx];
}
void ngtcp2_pmtud_probe_sent(ngtcp2_pmtud *pmtud, ngtcp2_duration pto,
ngtcp2_tstamp ts) {
ngtcp2_tstamp timeout;
if (++pmtud->num_pkts_sent < NGTCP2_PMTUD_PROBE_NUM_MAX) {
timeout = pto;
} else {
timeout = 3 * pto;
}
pmtud->expiry = ts + timeout;
}
int ngtcp2_pmtud_require_probe(ngtcp2_pmtud *pmtud) {
return pmtud->expiry == UINT64_MAX;
}
static void pmtud_next_probe(ngtcp2_pmtud *pmtud) {
assert(pmtud->mtu_idx < NGTCP2_MTU_PROBESLEN);
++pmtud->mtu_idx;
pmtud->num_pkts_sent = 0;
pmtud->expiry = UINT64_MAX;
for (; pmtud->mtu_idx < NGTCP2_MTU_PROBESLEN; ++pmtud->mtu_idx) {
if (mtu_probes[pmtud->mtu_idx] <= pmtud->max_udp_payload_size ||
mtu_probes[pmtud->mtu_idx] > pmtud->hard_max_udp_payload_size) {
continue;
}
if (mtu_probes[pmtud->mtu_idx] < pmtud->min_fail_udp_payload_size) {
break;
}
}
}
void ngtcp2_pmtud_probe_success(ngtcp2_pmtud *pmtud, size_t payloadlen) {
pmtud->max_udp_payload_size =
ngtcp2_max(pmtud->max_udp_payload_size, payloadlen);
assert(pmtud->mtu_idx < NGTCP2_MTU_PROBESLEN);
if (mtu_probes[pmtud->mtu_idx] > pmtud->max_udp_payload_size) {
return;
}
pmtud_next_probe(pmtud);
}
void ngtcp2_pmtud_handle_expiry(ngtcp2_pmtud *pmtud, ngtcp2_tstamp ts) {
if (ts < pmtud->expiry) {
return;
}
pmtud->expiry = UINT64_MAX;
if (pmtud->num_pkts_sent < NGTCP2_PMTUD_PROBE_NUM_MAX) {
return;
}
pmtud->min_fail_udp_payload_size =
ngtcp2_min(pmtud->min_fail_udp_payload_size, mtu_probes[pmtud->mtu_idx]);
pmtud_next_probe(pmtud);
}
int ngtcp2_pmtud_finished(ngtcp2_pmtud *pmtud) {
return pmtud->mtu_idx >= NGTCP2_MTU_PROBESLEN;
}
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