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-rw-r--r--lib/ngtcp2_pmtud.c160
1 files changed, 160 insertions, 0 deletions
diff --git a/lib/ngtcp2_pmtud.c b/lib/ngtcp2_pmtud.c
new file mode 100644
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--- /dev/null
+++ b/lib/ngtcp2_pmtud.c
@@ -0,0 +1,160 @@
+/*
+ * 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;
+}