486 lines
14 KiB
C
486 lines
14 KiB
C
#include "internal/quic_cc.h"
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#include "internal/quic_types.h"
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#include "internal/safe_math.h"
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OSSL_SAFE_MATH_UNSIGNED(u64, uint64_t)
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typedef struct ossl_cc_newreno_st {
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/* Dependencies. */
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OSSL_TIME (*now_cb)(void *arg);
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void *now_cb_arg;
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/* 'Constants' (which we allow to be configurable). */
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uint64_t k_init_wnd, k_min_wnd;
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uint32_t k_loss_reduction_factor_num, k_loss_reduction_factor_den;
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uint32_t persistent_cong_thresh;
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/* State. */
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size_t max_dgram_size;
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uint64_t bytes_in_flight, cong_wnd, slow_start_thresh, bytes_acked;
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OSSL_TIME cong_recovery_start_time;
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/* Unflushed state during multiple on-loss calls. */
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int processing_loss; /* 1 if not flushed */
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OSSL_TIME tx_time_of_last_loss;
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/* Diagnostic state. */
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int in_congestion_recovery;
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/* Diagnostic output locations. */
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size_t *p_diag_max_dgram_payload_len;
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uint64_t *p_diag_cur_cwnd_size;
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uint64_t *p_diag_min_cwnd_size;
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uint64_t *p_diag_cur_bytes_in_flight;
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uint32_t *p_diag_cur_state;
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} OSSL_CC_NEWRENO;
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#define MIN_MAX_INIT_WND_SIZE 14720 /* RFC 9002 s. 7.2 */
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/* TODO(QUIC FUTURE): Pacing support. */
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static void newreno_set_max_dgram_size(OSSL_CC_NEWRENO *nr,
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size_t max_dgram_size);
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static void newreno_update_diag(OSSL_CC_NEWRENO *nr);
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static void newreno_reset(OSSL_CC_DATA *cc);
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static OSSL_CC_DATA *newreno_new(OSSL_TIME (*now_cb)(void *arg),
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void *now_cb_arg)
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{
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OSSL_CC_NEWRENO *nr;
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if ((nr = OPENSSL_zalloc(sizeof(*nr))) == NULL)
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return NULL;
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nr->now_cb = now_cb;
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nr->now_cb_arg = now_cb_arg;
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newreno_set_max_dgram_size(nr, QUIC_MIN_INITIAL_DGRAM_LEN);
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newreno_reset((OSSL_CC_DATA *)nr);
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return (OSSL_CC_DATA *)nr;
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}
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static void newreno_free(OSSL_CC_DATA *cc)
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{
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OPENSSL_free(cc);
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}
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static void newreno_set_max_dgram_size(OSSL_CC_NEWRENO *nr,
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size_t max_dgram_size)
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{
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size_t max_init_wnd;
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int is_reduced = (max_dgram_size < nr->max_dgram_size);
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nr->max_dgram_size = max_dgram_size;
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max_init_wnd = 2 * max_dgram_size;
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if (max_init_wnd < MIN_MAX_INIT_WND_SIZE)
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max_init_wnd = MIN_MAX_INIT_WND_SIZE;
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nr->k_init_wnd = 10 * max_dgram_size;
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if (nr->k_init_wnd > max_init_wnd)
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nr->k_init_wnd = max_init_wnd;
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nr->k_min_wnd = 2 * max_dgram_size;
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if (is_reduced)
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nr->cong_wnd = nr->k_init_wnd;
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newreno_update_diag(nr);
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}
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static void newreno_reset(OSSL_CC_DATA *cc)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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nr->k_loss_reduction_factor_num = 1;
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nr->k_loss_reduction_factor_den = 2;
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nr->persistent_cong_thresh = 3;
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nr->cong_wnd = nr->k_init_wnd;
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nr->bytes_in_flight = 0;
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nr->bytes_acked = 0;
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nr->slow_start_thresh = UINT64_MAX;
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nr->cong_recovery_start_time = ossl_time_zero();
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nr->processing_loss = 0;
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nr->tx_time_of_last_loss = ossl_time_zero();
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nr->in_congestion_recovery = 0;
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}
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static int newreno_set_input_params(OSSL_CC_DATA *cc, const OSSL_PARAM *params)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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const OSSL_PARAM *p;
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size_t value;
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p = OSSL_PARAM_locate_const(params, OSSL_CC_OPTION_MAX_DGRAM_PAYLOAD_LEN);
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if (p != NULL) {
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if (!OSSL_PARAM_get_size_t(p, &value))
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return 0;
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if (value < QUIC_MIN_INITIAL_DGRAM_LEN)
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return 0;
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newreno_set_max_dgram_size(nr, value);
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}
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return 1;
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}
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static int bind_diag(OSSL_PARAM *params, const char *param_name, size_t len,
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void **pp)
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{
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const OSSL_PARAM *p = OSSL_PARAM_locate_const(params, param_name);
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*pp = NULL;
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if (p == NULL)
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return 1;
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if (p->data_type != OSSL_PARAM_UNSIGNED_INTEGER
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|| p->data_size != len)
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return 0;
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*pp = p->data;
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return 1;
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}
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static int newreno_bind_diagnostic(OSSL_CC_DATA *cc, OSSL_PARAM *params)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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size_t *new_p_max_dgram_payload_len;
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uint64_t *new_p_cur_cwnd_size;
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uint64_t *new_p_min_cwnd_size;
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uint64_t *new_p_cur_bytes_in_flight;
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uint32_t *new_p_cur_state;
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if (!bind_diag(params, OSSL_CC_OPTION_MAX_DGRAM_PAYLOAD_LEN,
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sizeof(size_t), (void **)&new_p_max_dgram_payload_len)
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|| !bind_diag(params, OSSL_CC_OPTION_CUR_CWND_SIZE,
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sizeof(uint64_t), (void **)&new_p_cur_cwnd_size)
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|| !bind_diag(params, OSSL_CC_OPTION_MIN_CWND_SIZE,
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sizeof(uint64_t), (void **)&new_p_min_cwnd_size)
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|| !bind_diag(params, OSSL_CC_OPTION_CUR_BYTES_IN_FLIGHT,
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sizeof(uint64_t), (void **)&new_p_cur_bytes_in_flight)
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|| !bind_diag(params, OSSL_CC_OPTION_CUR_STATE,
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sizeof(uint32_t), (void **)&new_p_cur_state))
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return 0;
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if (new_p_max_dgram_payload_len != NULL)
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nr->p_diag_max_dgram_payload_len = new_p_max_dgram_payload_len;
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if (new_p_cur_cwnd_size != NULL)
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nr->p_diag_cur_cwnd_size = new_p_cur_cwnd_size;
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if (new_p_min_cwnd_size != NULL)
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nr->p_diag_min_cwnd_size = new_p_min_cwnd_size;
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if (new_p_cur_bytes_in_flight != NULL)
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nr->p_diag_cur_bytes_in_flight = new_p_cur_bytes_in_flight;
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if (new_p_cur_state != NULL)
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nr->p_diag_cur_state = new_p_cur_state;
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newreno_update_diag(nr);
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return 1;
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}
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static void unbind_diag(OSSL_PARAM *params, const char *param_name,
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void **pp)
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{
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const OSSL_PARAM *p = OSSL_PARAM_locate_const(params, param_name);
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if (p != NULL)
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*pp = NULL;
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}
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static int newreno_unbind_diagnostic(OSSL_CC_DATA *cc, OSSL_PARAM *params)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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unbind_diag(params, OSSL_CC_OPTION_MAX_DGRAM_PAYLOAD_LEN,
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(void **)&nr->p_diag_max_dgram_payload_len);
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unbind_diag(params, OSSL_CC_OPTION_CUR_CWND_SIZE,
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(void **)&nr->p_diag_cur_cwnd_size);
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unbind_diag(params, OSSL_CC_OPTION_MIN_CWND_SIZE,
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(void **)&nr->p_diag_min_cwnd_size);
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unbind_diag(params, OSSL_CC_OPTION_CUR_BYTES_IN_FLIGHT,
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(void **)&nr->p_diag_cur_bytes_in_flight);
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unbind_diag(params, OSSL_CC_OPTION_CUR_STATE,
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(void **)&nr->p_diag_cur_state);
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return 1;
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}
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static void newreno_update_diag(OSSL_CC_NEWRENO *nr)
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{
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if (nr->p_diag_max_dgram_payload_len != NULL)
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*nr->p_diag_max_dgram_payload_len = nr->max_dgram_size;
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if (nr->p_diag_cur_cwnd_size != NULL)
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*nr->p_diag_cur_cwnd_size = nr->cong_wnd;
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if (nr->p_diag_min_cwnd_size != NULL)
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*nr->p_diag_min_cwnd_size = nr->k_min_wnd;
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if (nr->p_diag_cur_bytes_in_flight != NULL)
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*nr->p_diag_cur_bytes_in_flight = nr->bytes_in_flight;
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if (nr->p_diag_cur_state != NULL) {
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if (nr->in_congestion_recovery)
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*nr->p_diag_cur_state = 'R';
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else if (nr->cong_wnd < nr->slow_start_thresh)
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*nr->p_diag_cur_state = 'S';
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else
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*nr->p_diag_cur_state = 'A';
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}
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}
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static int newreno_in_cong_recovery(OSSL_CC_NEWRENO *nr, OSSL_TIME tx_time)
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{
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return ossl_time_compare(tx_time, nr->cong_recovery_start_time) <= 0;
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}
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static void newreno_cong(OSSL_CC_NEWRENO *nr, OSSL_TIME tx_time)
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{
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int err = 0;
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/* No reaction if already in a recovery period. */
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if (newreno_in_cong_recovery(nr, tx_time))
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return;
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/* Start a new recovery period. */
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nr->in_congestion_recovery = 1;
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nr->cong_recovery_start_time = nr->now_cb(nr->now_cb_arg);
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/* slow_start_thresh = cong_wnd * loss_reduction_factor */
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nr->slow_start_thresh
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= safe_muldiv_u64(nr->cong_wnd,
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nr->k_loss_reduction_factor_num,
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nr->k_loss_reduction_factor_den,
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&err);
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if (err)
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nr->slow_start_thresh = UINT64_MAX;
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nr->cong_wnd = nr->slow_start_thresh;
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if (nr->cong_wnd < nr->k_min_wnd)
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nr->cong_wnd = nr->k_min_wnd;
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}
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static void newreno_flush(OSSL_CC_NEWRENO *nr, uint32_t flags)
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{
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if (!nr->processing_loss)
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return;
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newreno_cong(nr, nr->tx_time_of_last_loss);
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if ((flags & OSSL_CC_LOST_FLAG_PERSISTENT_CONGESTION) != 0) {
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nr->cong_wnd = nr->k_min_wnd;
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nr->cong_recovery_start_time = ossl_time_zero();
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}
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nr->processing_loss = 0;
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newreno_update_diag(nr);
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}
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static uint64_t newreno_get_tx_allowance(OSSL_CC_DATA *cc)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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if (nr->bytes_in_flight >= nr->cong_wnd)
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return 0;
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return nr->cong_wnd - nr->bytes_in_flight;
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}
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static OSSL_TIME newreno_get_wakeup_deadline(OSSL_CC_DATA *cc)
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{
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if (newreno_get_tx_allowance(cc) > 0) {
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/* We have TX allowance now so wakeup immediately */
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return ossl_time_zero();
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} else {
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/*
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* The NewReno congestion controller does not vary its state in time,
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* only in response to stimulus.
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*/
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return ossl_time_infinite();
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}
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}
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static int newreno_on_data_sent(OSSL_CC_DATA *cc, uint64_t num_bytes)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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nr->bytes_in_flight += num_bytes;
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newreno_update_diag(nr);
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return 1;
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}
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static int newreno_is_cong_limited(OSSL_CC_NEWRENO *nr)
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{
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uint64_t wnd_rem;
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/* We are congestion-limited if we are already at the congestion window. */
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if (nr->bytes_in_flight >= nr->cong_wnd)
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return 1;
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wnd_rem = nr->cong_wnd - nr->bytes_in_flight;
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/*
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* Consider ourselves congestion-limited if less than three datagrams' worth
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* of congestion window remains to be spent, or if we are in slow start and
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* have consumed half of our window.
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*/
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return (nr->cong_wnd < nr->slow_start_thresh && wnd_rem <= nr->cong_wnd / 2)
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|| wnd_rem <= 3 * nr->max_dgram_size;
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}
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static int newreno_on_data_acked(OSSL_CC_DATA *cc,
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const OSSL_CC_ACK_INFO *info)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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/*
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* Packet has been acked. Firstly, remove it from the aggregate count of
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* bytes in flight.
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*/
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nr->bytes_in_flight -= info->tx_size;
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/*
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* We use acknowledgement of data as a signal that we are not at channel
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* capacity and that it may be reasonable to increase the congestion window.
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* However, acknowledgement is not a useful signal that there is further
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* capacity if we are not actually saturating the congestion window that we
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* already have (for example, if the application is not generating much data
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* or we are limited by flow control). Therefore, we only expand the
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* congestion window if we are consuming a significant fraction of the
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* congestion window.
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*/
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if (!newreno_is_cong_limited(nr))
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goto out;
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/*
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* We can handle acknowledgement of a packet in one of three ways
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* depending on our current state:
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*
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* - Congestion Recovery: Do nothing. We don't start increasing
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* the congestion window in response to acknowledgements until
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* we are no longer in the Congestion Recovery state.
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*
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* - Slow Start: Increase the congestion window using the slow
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* start scale.
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*
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* - Congestion Avoidance: Increase the congestion window using
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* the congestion avoidance scale.
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*/
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if (newreno_in_cong_recovery(nr, info->tx_time)) {
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/* Congestion recovery, do nothing. */
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} else if (nr->cong_wnd < nr->slow_start_thresh) {
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/* When this condition is true we are in the Slow Start state. */
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nr->cong_wnd += info->tx_size;
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nr->in_congestion_recovery = 0;
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} else {
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/* Otherwise, we are in the Congestion Avoidance state. */
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nr->bytes_acked += info->tx_size;
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/*
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* Avoid integer division as per RFC 9002 s. B.5. / RFC3465 s. 2.1.
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*/
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if (nr->bytes_acked >= nr->cong_wnd) {
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nr->bytes_acked -= nr->cong_wnd;
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nr->cong_wnd += nr->max_dgram_size;
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}
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nr->in_congestion_recovery = 0;
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}
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out:
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newreno_update_diag(nr);
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return 1;
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}
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static int newreno_on_data_lost(OSSL_CC_DATA *cc,
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const OSSL_CC_LOSS_INFO *info)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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if (info->tx_size > nr->bytes_in_flight)
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return 0;
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nr->bytes_in_flight -= info->tx_size;
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if (!nr->processing_loss) {
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if (ossl_time_compare(info->tx_time, nr->tx_time_of_last_loss) <= 0)
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/*
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* After triggering congestion due to a lost packet at time t, don't
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* trigger congestion again due to any subsequently detected lost
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* packet at a time s < t, as we've effectively already signalled
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* congestion on loss of that and subsequent packets.
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*/
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goto out;
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nr->processing_loss = 1;
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/*
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* Cancel any pending window increase in the Congestion Avoidance state.
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*/
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nr->bytes_acked = 0;
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}
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nr->tx_time_of_last_loss
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= ossl_time_max(nr->tx_time_of_last_loss, info->tx_time);
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out:
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newreno_update_diag(nr);
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return 1;
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}
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static int newreno_on_data_lost_finished(OSSL_CC_DATA *cc, uint32_t flags)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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newreno_flush(nr, flags);
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return 1;
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}
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static int newreno_on_data_invalidated(OSSL_CC_DATA *cc,
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uint64_t num_bytes)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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nr->bytes_in_flight -= num_bytes;
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newreno_update_diag(nr);
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return 1;
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}
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static int newreno_on_ecn(OSSL_CC_DATA *cc,
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const OSSL_CC_ECN_INFO *info)
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{
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OSSL_CC_NEWRENO *nr = (OSSL_CC_NEWRENO *)cc;
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nr->processing_loss = 1;
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nr->bytes_acked = 0;
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nr->tx_time_of_last_loss = info->largest_acked_time;
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newreno_flush(nr, 0);
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return 1;
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}
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const OSSL_CC_METHOD ossl_cc_newreno_method = {
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newreno_new,
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newreno_free,
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newreno_reset,
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newreno_set_input_params,
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newreno_bind_diagnostic,
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newreno_unbind_diagnostic,
|
|
newreno_get_tx_allowance,
|
|
newreno_get_wakeup_deadline,
|
|
newreno_on_data_sent,
|
|
newreno_on_data_acked,
|
|
newreno_on_data_lost,
|
|
newreno_on_data_lost_finished,
|
|
newreno_on_data_invalidated,
|
|
newreno_on_ecn,
|
|
};
|