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/*
* Ouroboros - Copyright (C) 2016 - 2026
*
* Congestion Avoidance
*
* Dimitri Staessens <dimitri@ouroboros.rocks>
* Sander Vrijders <sander@ouroboros.rocks>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., http://www.fsf.org/about/contact/.
*/
#define OUROBOROS_PREFIX "ca"
#include "config.h"
#include <ouroboros/list.h>
#include <ouroboros/logs.h>
#include "ca.h"
#include "ca/pol.h"
#include <pthread.h>
#include <stdlib.h>
/*
* A ca_ctx holds congestion state for a (peer address, qos cube) PATH,
* not for a flow. In the default build the façade interns one ctx per
* (addr, qc) and shares it across every flow on that path; the policy
* runs on the shared ctx and cannot tell one flow from many. Per-flow
* ctx (IPCP_CA_PER_FLOW) is a testing build only: it skips interning so
* every flow gets its own ctx.
*/
struct ca_ctx {
uint64_t addr;
qoscube_t qc;
size_t refs;
void * pol; /* policy ctx (ops->ctx_create result) */
struct list_head next;
};
struct {
struct ca_ops * ops;
#ifndef IPCP_CA_PER_FLOW
struct list_head buckets[CA_BUCKETS];
pthread_mutex_t mtx;
#endif
} ca;
int ca_init(enum pol_cong_avoid pol)
{
#ifndef IPCP_CA_PER_FLOW
size_t i;
#endif
switch(pol) {
case CA_NONE:
log_dbg("Disabling congestion control.");
ca.ops = &nop_ca_ops;
break;
case CA_MB_ECN:
log_dbg("Using multi-bit ECN.");
ca.ops = &mb_ecn_ca_ops;
break;
default:
return -1;
}
#ifndef IPCP_CA_PER_FLOW
for (i = 0; i < CA_BUCKETS; i++)
list_head_init(&ca.buckets[i]);
if (pthread_mutex_init(&ca.mtx, NULL) != 0)
return -1;
#endif
return 0;
}
void ca_fini(void)
{
#ifndef IPCP_CA_PER_FLOW
size_t i;
/* Data path is stopped; drain any ctx a flow left interned. */
for (i = 0; i < CA_BUCKETS; i++) {
struct list_head * p;
struct list_head * h;
list_for_each_safe(p, h, &ca.buckets[i]) {
struct ca_ctx * ctx;
ctx = list_entry(p, struct ca_ctx, next);
list_del(&ctx->next);
ca.ops->ctx_destroy(ctx->pol);
free(ctx);
}
}
pthread_mutex_destroy(&ca.mtx);
#endif
ca.ops = NULL;
}
#ifndef IPCP_CA_PER_FLOW
static size_t ca_bucket(uint64_t addr,
qoscube_t qc)
{
return (addr ^ (addr >> 32) ^ (uint64_t) qc) & (CA_BUCKETS - 1);
}
#endif
void * ca_ctx_get(uint64_t addr,
qoscube_t qc)
{
struct ca_ctx * ctx;
#ifndef IPCP_CA_PER_FLOW
struct list_head * p;
size_t b = ca_bucket(addr, qc);
pthread_mutex_lock(&ca.mtx);
list_for_each(p, &ca.buckets[b]) {
ctx = list_entry(p, struct ca_ctx, next);
if (ctx->addr == addr && ctx->qc == qc) {
ctx->refs++;
pthread_mutex_unlock(&ca.mtx);
return ctx;
}
}
#endif
ctx = malloc(sizeof(*ctx));
if (ctx == NULL)
goto fail_ctx;
ctx->pol = ca.ops->ctx_create();
if (ctx->pol == NULL)
goto fail_pol;
ctx->addr = addr;
ctx->qc = qc;
ctx->refs = 1;
#ifndef IPCP_CA_PER_FLOW
list_add(&ctx->next, &ca.buckets[b]);
pthread_mutex_unlock(&ca.mtx);
#endif
return ctx;
fail_pol:
free(ctx);
fail_ctx:
#ifndef IPCP_CA_PER_FLOW
pthread_mutex_unlock(&ca.mtx);
#endif
return NULL;
}
void ca_ctx_put(void * _ctx)
{
struct ca_ctx * ctx = _ctx;
#ifndef IPCP_CA_PER_FLOW
pthread_mutex_lock(&ca.mtx);
if (--ctx->refs > 0) {
pthread_mutex_unlock(&ca.mtx);
return;
}
list_del(&ctx->next);
pthread_mutex_unlock(&ca.mtx);
#endif
ca.ops->ctx_destroy(ctx->pol);
free(ctx);
}
time_t ca_ctx_update_snd(void * _ctx,
size_t len,
uint8_t lecn,
uint64_t * ftag)
{
struct ca_ctx * ctx = _ctx;
return ca.ops->ctx_update_snd(ctx->pol, len, lecn, ftag);
}
bool ca_ctx_update_rcv(void * _ctx,
size_t len,
uint8_t ecn,
uint8_t cap,
uint16_t * ece,
uint8_t * fcap)
{
struct ca_ctx * ctx = _ctx;
return ca.ops->ctx_update_rcv(ctx->pol, len, ecn, cap, ece, fcap);
}
void ca_ctx_update_ece(void * _ctx,
uint16_t ece,
uint8_t cap)
{
struct ca_ctx * ctx = _ctx;
return ca.ops->ctx_update_ece(ctx->pol, ece, cap);
}
int ca_calc_ecn(size_t queued,
uint8_t * ecn,
qoscube_t qc,
size_t len)
{
return ca.ops->calc_ecn(queued, ecn, qc, len);
}
bool ca_marks_ecn(void)
{
return ca.ops->marks_ecn;
}
ssize_t ca_print_stats(void * _ctx,
char * buf,
size_t len)
{
struct ca_ctx * ctx = _ctx;
if (ca.ops->print_stats == NULL)
return 0;
return ca.ops->print_stats(ctx->pol, buf, len);
}
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