Mercurial > hg > nginx
view src/http/modules/ngx_http_limit_conn_module.c @ 7281:bd6563e81cea
Limit req: improved handling of negative times.
Negative times can appear since workers only update time on an event
loop iteration start. If a worker was blocked for a long time during
an event loop iteration, it is possible that another worker already
updated the time stored in the node. As such, time since last update
of the node (ms) will be negative.
Previous code used ngx_abs(ms) in the calculations. That is, negative
times were effectively treated as positive ones. As a result, it was
not possible to maintain high request rates, where the same node can be
updated multiple times from during an event loop iteration.
In particular, this affected setups with many SSL handshakes, see
http://mailman.nginx.org/pipermail/nginx/2018-May/056291.html.
Fix is to only update the last update time stored in the node if the
new time is larger than previously stored one. If a future time is
stored in the node, we preserve this time as is.
To prevent breaking things on platforms without monotonic time available
if system time is updated backwards, a safety limit of 60 seconds is
used. If the time stored in the node is more than 60 seconds in the future,
we assume that the time was changed backwards and update lr->last
to the current time.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Wed, 30 May 2018 15:40:34 +0300 |
parents | f01ab2dbcfdc |
children | 359b0ea2b067 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { u_char color; u_char len; u_short conn; u_char data[1]; } ngx_http_limit_conn_node_t; typedef struct { ngx_shm_zone_t *shm_zone; ngx_rbtree_node_t *node; } ngx_http_limit_conn_cleanup_t; typedef struct { ngx_rbtree_t *rbtree; ngx_http_complex_value_t key; } ngx_http_limit_conn_ctx_t; typedef struct { ngx_shm_zone_t *shm_zone; ngx_uint_t conn; } ngx_http_limit_conn_limit_t; typedef struct { ngx_array_t limits; ngx_uint_t log_level; ngx_uint_t status_code; } ngx_http_limit_conn_conf_t; static ngx_rbtree_node_t *ngx_http_limit_conn_lookup(ngx_rbtree_t *rbtree, ngx_str_t *key, uint32_t hash); static void ngx_http_limit_conn_cleanup(void *data); static ngx_inline void ngx_http_limit_conn_cleanup_all(ngx_pool_t *pool); static void *ngx_http_limit_conn_create_conf(ngx_conf_t *cf); static char *ngx_http_limit_conn_merge_conf(ngx_conf_t *cf, void *parent, void *child); static char *ngx_http_limit_conn_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_http_limit_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_int_t ngx_http_limit_conn_init(ngx_conf_t *cf); static ngx_conf_enum_t ngx_http_limit_conn_log_levels[] = { { ngx_string("info"), NGX_LOG_INFO }, { ngx_string("notice"), NGX_LOG_NOTICE }, { ngx_string("warn"), NGX_LOG_WARN }, { ngx_string("error"), NGX_LOG_ERR }, { ngx_null_string, 0 } }; static ngx_conf_num_bounds_t ngx_http_limit_conn_status_bounds = { ngx_conf_check_num_bounds, 400, 599 }; static ngx_command_t ngx_http_limit_conn_commands[] = { { ngx_string("limit_conn_zone"), NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE2, ngx_http_limit_conn_zone, 0, 0, NULL }, { ngx_string("limit_conn"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE2, ngx_http_limit_conn, NGX_HTTP_LOC_CONF_OFFSET, 0, NULL }, { ngx_string("limit_conn_log_level"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_conf_set_enum_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_limit_conn_conf_t, log_level), &ngx_http_limit_conn_log_levels }, { ngx_string("limit_conn_status"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_limit_conn_conf_t, status_code), &ngx_http_limit_conn_status_bounds }, ngx_null_command }; static ngx_http_module_t ngx_http_limit_conn_module_ctx = { NULL, /* preconfiguration */ ngx_http_limit_conn_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_limit_conn_create_conf, /* create location configuration */ ngx_http_limit_conn_merge_conf /* merge location configuration */ }; ngx_module_t ngx_http_limit_conn_module = { NGX_MODULE_V1, &ngx_http_limit_conn_module_ctx, /* module context */ ngx_http_limit_conn_commands, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_int_t ngx_http_limit_conn_handler(ngx_http_request_t *r) { size_t n; uint32_t hash; ngx_str_t key; ngx_uint_t i; ngx_slab_pool_t *shpool; ngx_rbtree_node_t *node; ngx_pool_cleanup_t *cln; ngx_http_limit_conn_ctx_t *ctx; ngx_http_limit_conn_node_t *lc; ngx_http_limit_conn_conf_t *lccf; ngx_http_limit_conn_limit_t *limits; ngx_http_limit_conn_cleanup_t *lccln; if (r->main->limit_conn_set) { return NGX_DECLINED; } lccf = ngx_http_get_module_loc_conf(r, ngx_http_limit_conn_module); limits = lccf->limits.elts; for (i = 0; i < lccf->limits.nelts; i++) { ctx = limits[i].shm_zone->data; if (ngx_http_complex_value(r, &ctx->key, &key) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (key.len == 0) { continue; } if (key.len > 255) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "the value of the \"%V\" key " "is more than 255 bytes: \"%V\"", &ctx->key.value, &key); continue; } r->main->limit_conn_set = 1; hash = ngx_crc32_short(key.data, key.len); shpool = (ngx_slab_pool_t *) limits[i].shm_zone->shm.addr; ngx_shmtx_lock(&shpool->mutex); node = ngx_http_limit_conn_lookup(ctx->rbtree, &key, hash); if (node == NULL) { n = offsetof(ngx_rbtree_node_t, color) + offsetof(ngx_http_limit_conn_node_t, data) + key.len; node = ngx_slab_alloc_locked(shpool, n); if (node == NULL) { ngx_shmtx_unlock(&shpool->mutex); ngx_http_limit_conn_cleanup_all(r->pool); return lccf->status_code; } lc = (ngx_http_limit_conn_node_t *) &node->color; node->key = hash; lc->len = (u_char) key.len; lc->conn = 1; ngx_memcpy(lc->data, key.data, key.len); ngx_rbtree_insert(ctx->rbtree, node); } else { lc = (ngx_http_limit_conn_node_t *) &node->color; if ((ngx_uint_t) lc->conn >= limits[i].conn) { ngx_shmtx_unlock(&shpool->mutex); ngx_log_error(lccf->log_level, r->connection->log, 0, "limiting connections by zone \"%V\"", &limits[i].shm_zone->shm.name); ngx_http_limit_conn_cleanup_all(r->pool); return lccf->status_code; } lc->conn++; } ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "limit conn: %08Xi %d", node->key, lc->conn); ngx_shmtx_unlock(&shpool->mutex); cln = ngx_pool_cleanup_add(r->pool, sizeof(ngx_http_limit_conn_cleanup_t)); if (cln == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } cln->handler = ngx_http_limit_conn_cleanup; lccln = cln->data; lccln->shm_zone = limits[i].shm_zone; lccln->node = node; } return NGX_DECLINED; } static void ngx_http_limit_conn_rbtree_insert_value(ngx_rbtree_node_t *temp, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel) { ngx_rbtree_node_t **p; ngx_http_limit_conn_node_t *lcn, *lcnt; for ( ;; ) { if (node->key < temp->key) { p = &temp->left; } else if (node->key > temp->key) { p = &temp->right; } else { /* node->key == temp->key */ lcn = (ngx_http_limit_conn_node_t *) &node->color; lcnt = (ngx_http_limit_conn_node_t *) &temp->color; p = (ngx_memn2cmp(lcn->data, lcnt->data, lcn->len, lcnt->len) < 0) ? &temp->left : &temp->right; } if (*p == sentinel) { break; } temp = *p; } *p = node; node->parent = temp; node->left = sentinel; node->right = sentinel; ngx_rbt_red(node); } static ngx_rbtree_node_t * ngx_http_limit_conn_lookup(ngx_rbtree_t *rbtree, ngx_str_t *key, uint32_t hash) { ngx_int_t rc; ngx_rbtree_node_t *node, *sentinel; ngx_http_limit_conn_node_t *lcn; node = rbtree->root; sentinel = rbtree->sentinel; while (node != sentinel) { if (hash < node->key) { node = node->left; continue; } if (hash > node->key) { node = node->right; continue; } /* hash == node->key */ lcn = (ngx_http_limit_conn_node_t *) &node->color; rc = ngx_memn2cmp(key->data, lcn->data, key->len, (size_t) lcn->len); if (rc == 0) { return node; } node = (rc < 0) ? node->left : node->right; } return NULL; } static void ngx_http_limit_conn_cleanup(void *data) { ngx_http_limit_conn_cleanup_t *lccln = data; ngx_slab_pool_t *shpool; ngx_rbtree_node_t *node; ngx_http_limit_conn_ctx_t *ctx; ngx_http_limit_conn_node_t *lc; ctx = lccln->shm_zone->data; shpool = (ngx_slab_pool_t *) lccln->shm_zone->shm.addr; node = lccln->node; lc = (ngx_http_limit_conn_node_t *) &node->color; ngx_shmtx_lock(&shpool->mutex); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, lccln->shm_zone->shm.log, 0, "limit conn cleanup: %08Xi %d", node->key, lc->conn); lc->conn--; if (lc->conn == 0) { ngx_rbtree_delete(ctx->rbtree, node); ngx_slab_free_locked(shpool, node); } ngx_shmtx_unlock(&shpool->mutex); } static ngx_inline void ngx_http_limit_conn_cleanup_all(ngx_pool_t *pool) { ngx_pool_cleanup_t *cln; cln = pool->cleanup; while (cln && cln->handler == ngx_http_limit_conn_cleanup) { ngx_http_limit_conn_cleanup(cln->data); cln = cln->next; } pool->cleanup = cln; } static ngx_int_t ngx_http_limit_conn_init_zone(ngx_shm_zone_t *shm_zone, void *data) { ngx_http_limit_conn_ctx_t *octx = data; size_t len; ngx_slab_pool_t *shpool; ngx_rbtree_node_t *sentinel; ngx_http_limit_conn_ctx_t *ctx; ctx = shm_zone->data; if (octx) { if (ctx->key.value.len != octx->key.value.len || ngx_strncmp(ctx->key.value.data, octx->key.value.data, ctx->key.value.len) != 0) { ngx_log_error(NGX_LOG_EMERG, shm_zone->shm.log, 0, "limit_conn_zone \"%V\" uses the \"%V\" key " "while previously it used the \"%V\" key", &shm_zone->shm.name, &ctx->key.value, &octx->key.value); return NGX_ERROR; } ctx->rbtree = octx->rbtree; return NGX_OK; } shpool = (ngx_slab_pool_t *) shm_zone->shm.addr; if (shm_zone->shm.exists) { ctx->rbtree = shpool->data; return NGX_OK; } ctx->rbtree = ngx_slab_alloc(shpool, sizeof(ngx_rbtree_t)); if (ctx->rbtree == NULL) { return NGX_ERROR; } shpool->data = ctx->rbtree; sentinel = ngx_slab_alloc(shpool, sizeof(ngx_rbtree_node_t)); if (sentinel == NULL) { return NGX_ERROR; } ngx_rbtree_init(ctx->rbtree, sentinel, ngx_http_limit_conn_rbtree_insert_value); len = sizeof(" in limit_conn_zone \"\"") + shm_zone->shm.name.len; shpool->log_ctx = ngx_slab_alloc(shpool, len); if (shpool->log_ctx == NULL) { return NGX_ERROR; } ngx_sprintf(shpool->log_ctx, " in limit_conn_zone \"%V\"%Z", &shm_zone->shm.name); return NGX_OK; } static void * ngx_http_limit_conn_create_conf(ngx_conf_t *cf) { ngx_http_limit_conn_conf_t *conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_limit_conn_conf_t)); if (conf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->limits.elts = NULL; */ conf->log_level = NGX_CONF_UNSET_UINT; conf->status_code = NGX_CONF_UNSET_UINT; return conf; } static char * ngx_http_limit_conn_merge_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_limit_conn_conf_t *prev = parent; ngx_http_limit_conn_conf_t *conf = child; if (conf->limits.elts == NULL) { conf->limits = prev->limits; } ngx_conf_merge_uint_value(conf->log_level, prev->log_level, NGX_LOG_ERR); ngx_conf_merge_uint_value(conf->status_code, prev->status_code, NGX_HTTP_SERVICE_UNAVAILABLE); return NGX_CONF_OK; } static char * ngx_http_limit_conn_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { u_char *p; ssize_t size; ngx_str_t *value, name, s; ngx_uint_t i; ngx_shm_zone_t *shm_zone; ngx_http_limit_conn_ctx_t *ctx; ngx_http_compile_complex_value_t ccv; value = cf->args->elts; ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_limit_conn_ctx_t)); if (ctx == NULL) { return NGX_CONF_ERROR; } ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t)); ccv.cf = cf; ccv.value = &value[1]; ccv.complex_value = &ctx->key; if (ngx_http_compile_complex_value(&ccv) != NGX_OK) { return NGX_CONF_ERROR; } size = 0; name.len = 0; for (i = 2; i < cf->args->nelts; i++) { if (ngx_strncmp(value[i].data, "zone=", 5) == 0) { name.data = value[i].data + 5; p = (u_char *) ngx_strchr(name.data, ':'); if (p == NULL) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid zone size \"%V\"", &value[i]); return NGX_CONF_ERROR; } name.len = p - name.data; s.data = p + 1; s.len = value[i].data + value[i].len - s.data; size = ngx_parse_size(&s); if (size == NGX_ERROR) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid zone size \"%V\"", &value[i]); return NGX_CONF_ERROR; } if (size < (ssize_t) (8 * ngx_pagesize)) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "zone \"%V\" is too small", &value[i]); return NGX_CONF_ERROR; } continue; } ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid parameter \"%V\"", &value[i]); return NGX_CONF_ERROR; } if (name.len == 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "\"%V\" must have \"zone\" parameter", &cmd->name); return NGX_CONF_ERROR; } shm_zone = ngx_shared_memory_add(cf, &name, size, &ngx_http_limit_conn_module); if (shm_zone == NULL) { return NGX_CONF_ERROR; } if (shm_zone->data) { ctx = shm_zone->data; ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "%V \"%V\" is already bound to key \"%V\"", &cmd->name, &name, &ctx->key.value); return NGX_CONF_ERROR; } shm_zone->init = ngx_http_limit_conn_init_zone; shm_zone->data = ctx; return NGX_CONF_OK; } static char * ngx_http_limit_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_shm_zone_t *shm_zone; ngx_http_limit_conn_conf_t *lccf = conf; ngx_http_limit_conn_limit_t *limit, *limits; ngx_str_t *value; ngx_int_t n; ngx_uint_t i; value = cf->args->elts; shm_zone = ngx_shared_memory_add(cf, &value[1], 0, &ngx_http_limit_conn_module); if (shm_zone == NULL) { return NGX_CONF_ERROR; } limits = lccf->limits.elts; if (limits == NULL) { if (ngx_array_init(&lccf->limits, cf->pool, 1, sizeof(ngx_http_limit_conn_limit_t)) != NGX_OK) { return NGX_CONF_ERROR; } } for (i = 0; i < lccf->limits.nelts; i++) { if (shm_zone == limits[i].shm_zone) { return "is duplicate"; } } n = ngx_atoi(value[2].data, value[2].len); if (n <= 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid number of connections \"%V\"", &value[2]); return NGX_CONF_ERROR; } if (n > 65535) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "connection limit must be less 65536"); return NGX_CONF_ERROR; } limit = ngx_array_push(&lccf->limits); if (limit == NULL) { return NGX_CONF_ERROR; } limit->conn = n; limit->shm_zone = shm_zone; return NGX_CONF_OK; } static ngx_int_t ngx_http_limit_conn_init(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *cmcf; cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_limit_conn_handler; return NGX_OK; }