Mercurial > hg > nginx
view src/http/modules/ngx_http_limit_req_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 | 903fb1ddc07f |
children | bca4dad0d3cb |
line wrap: on
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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 dummy; u_short len; ngx_queue_t queue; ngx_msec_t last; /* integer value, 1 corresponds to 0.001 r/s */ ngx_uint_t excess; ngx_uint_t count; u_char data[1]; } ngx_http_limit_req_node_t; typedef struct { ngx_rbtree_t rbtree; ngx_rbtree_node_t sentinel; ngx_queue_t queue; } ngx_http_limit_req_shctx_t; typedef struct { ngx_http_limit_req_shctx_t *sh; ngx_slab_pool_t *shpool; /* integer value, 1 corresponds to 0.001 r/s */ ngx_uint_t rate; ngx_http_complex_value_t key; ngx_http_limit_req_node_t *node; } ngx_http_limit_req_ctx_t; typedef struct { ngx_shm_zone_t *shm_zone; /* integer value, 1 corresponds to 0.001 r/s */ ngx_uint_t burst; ngx_uint_t nodelay; /* unsigned nodelay:1 */ } ngx_http_limit_req_limit_t; typedef struct { ngx_array_t limits; ngx_uint_t limit_log_level; ngx_uint_t delay_log_level; ngx_uint_t status_code; } ngx_http_limit_req_conf_t; static void ngx_http_limit_req_delay(ngx_http_request_t *r); static ngx_int_t ngx_http_limit_req_lookup(ngx_http_limit_req_limit_t *limit, ngx_uint_t hash, ngx_str_t *key, ngx_uint_t *ep, ngx_uint_t account); static ngx_msec_t ngx_http_limit_req_account(ngx_http_limit_req_limit_t *limits, ngx_uint_t n, ngx_uint_t *ep, ngx_http_limit_req_limit_t **limit); static void ngx_http_limit_req_expire(ngx_http_limit_req_ctx_t *ctx, ngx_uint_t n); static void *ngx_http_limit_req_create_conf(ngx_conf_t *cf); static char *ngx_http_limit_req_merge_conf(ngx_conf_t *cf, void *parent, void *child); static char *ngx_http_limit_req_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_http_limit_req(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_int_t ngx_http_limit_req_init(ngx_conf_t *cf); static ngx_conf_enum_t ngx_http_limit_req_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_req_status_bounds = { ngx_conf_check_num_bounds, 400, 599 }; static ngx_command_t ngx_http_limit_req_commands[] = { { ngx_string("limit_req_zone"), NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE3, ngx_http_limit_req_zone, 0, 0, NULL }, { ngx_string("limit_req"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE123, ngx_http_limit_req, NGX_HTTP_LOC_CONF_OFFSET, 0, NULL }, { ngx_string("limit_req_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_req_conf_t, limit_log_level), &ngx_http_limit_req_log_levels }, { ngx_string("limit_req_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_req_conf_t, status_code), &ngx_http_limit_req_status_bounds }, ngx_null_command }; static ngx_http_module_t ngx_http_limit_req_module_ctx = { NULL, /* preconfiguration */ ngx_http_limit_req_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_limit_req_create_conf, /* create location configuration */ ngx_http_limit_req_merge_conf /* merge location configuration */ }; ngx_module_t ngx_http_limit_req_module = { NGX_MODULE_V1, &ngx_http_limit_req_module_ctx, /* module context */ ngx_http_limit_req_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_req_handler(ngx_http_request_t *r) { uint32_t hash; ngx_str_t key; ngx_int_t rc; ngx_uint_t n, excess; ngx_msec_t delay; ngx_http_limit_req_ctx_t *ctx; ngx_http_limit_req_conf_t *lrcf; ngx_http_limit_req_limit_t *limit, *limits; if (r->main->limit_req_set) { return NGX_DECLINED; } lrcf = ngx_http_get_module_loc_conf(r, ngx_http_limit_req_module); limits = lrcf->limits.elts; excess = 0; rc = NGX_DECLINED; #if (NGX_SUPPRESS_WARN) limit = NULL; #endif for (n = 0; n < lrcf->limits.nelts; n++) { limit = &limits[n]; ctx = limit->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 > 65535) { ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "the value of the \"%V\" key " "is more than 65535 bytes: \"%V\"", &ctx->key.value, &key); continue; } hash = ngx_crc32_short(key.data, key.len); ngx_shmtx_lock(&ctx->shpool->mutex); rc = ngx_http_limit_req_lookup(limit, hash, &key, &excess, (n == lrcf->limits.nelts - 1)); ngx_shmtx_unlock(&ctx->shpool->mutex); ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "limit_req[%ui]: %i %ui.%03ui", n, rc, excess / 1000, excess % 1000); if (rc != NGX_AGAIN) { break; } } if (rc == NGX_DECLINED) { return NGX_DECLINED; } r->main->limit_req_set = 1; if (rc == NGX_BUSY || rc == NGX_ERROR) { if (rc == NGX_BUSY) { ngx_log_error(lrcf->limit_log_level, r->connection->log, 0, "limiting requests, excess: %ui.%03ui by zone \"%V\"", excess / 1000, excess % 1000, &limit->shm_zone->shm.name); } while (n--) { ctx = limits[n].shm_zone->data; if (ctx->node == NULL) { continue; } ngx_shmtx_lock(&ctx->shpool->mutex); ctx->node->count--; ngx_shmtx_unlock(&ctx->shpool->mutex); ctx->node = NULL; } return lrcf->status_code; } /* rc == NGX_AGAIN || rc == NGX_OK */ if (rc == NGX_AGAIN) { excess = 0; } delay = ngx_http_limit_req_account(limits, n, &excess, &limit); if (!delay) { return NGX_DECLINED; } ngx_log_error(lrcf->delay_log_level, r->connection->log, 0, "delaying request, excess: %ui.%03ui, by zone \"%V\"", excess / 1000, excess % 1000, &limit->shm_zone->shm.name); if (ngx_handle_read_event(r->connection->read, 0) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } r->read_event_handler = ngx_http_test_reading; r->write_event_handler = ngx_http_limit_req_delay; r->connection->write->delayed = 1; ngx_add_timer(r->connection->write, delay); return NGX_AGAIN; } static void ngx_http_limit_req_delay(ngx_http_request_t *r) { ngx_event_t *wev; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "limit_req delay"); wev = r->connection->write; if (wev->delayed) { if (ngx_handle_write_event(wev, 0) != NGX_OK) { ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR); } return; } if (ngx_handle_read_event(r->connection->read, 0) != NGX_OK) { ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR); return; } r->read_event_handler = ngx_http_block_reading; r->write_event_handler = ngx_http_core_run_phases; ngx_http_core_run_phases(r); } static void ngx_http_limit_req_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_req_node_t *lrn, *lrnt; for ( ;; ) { if (node->key < temp->key) { p = &temp->left; } else if (node->key > temp->key) { p = &temp->right; } else { /* node->key == temp->key */ lrn = (ngx_http_limit_req_node_t *) &node->color; lrnt = (ngx_http_limit_req_node_t *) &temp->color; p = (ngx_memn2cmp(lrn->data, lrnt->data, lrn->len, lrnt->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_int_t ngx_http_limit_req_lookup(ngx_http_limit_req_limit_t *limit, ngx_uint_t hash, ngx_str_t *key, ngx_uint_t *ep, ngx_uint_t account) { size_t size; ngx_int_t rc, excess; ngx_msec_t now; ngx_msec_int_t ms; ngx_rbtree_node_t *node, *sentinel; ngx_http_limit_req_ctx_t *ctx; ngx_http_limit_req_node_t *lr; now = ngx_current_msec; ctx = limit->shm_zone->data; node = ctx->sh->rbtree.root; sentinel = ctx->sh->rbtree.sentinel; while (node != sentinel) { if (hash < node->key) { node = node->left; continue; } if (hash > node->key) { node = node->right; continue; } /* hash == node->key */ lr = (ngx_http_limit_req_node_t *) &node->color; rc = ngx_memn2cmp(key->data, lr->data, key->len, (size_t) lr->len); if (rc == 0) { ngx_queue_remove(&lr->queue); ngx_queue_insert_head(&ctx->sh->queue, &lr->queue); ms = (ngx_msec_int_t) (now - lr->last); if (ms < -60000) { ms = 1; } else if (ms < 0) { ms = 0; } excess = lr->excess - ctx->rate * ms / 1000 + 1000; if (excess < 0) { excess = 0; } *ep = excess; if ((ngx_uint_t) excess > limit->burst) { return NGX_BUSY; } if (account) { lr->excess = excess; if (ms) { lr->last = now; } return NGX_OK; } lr->count++; ctx->node = lr; return NGX_AGAIN; } node = (rc < 0) ? node->left : node->right; } *ep = 0; size = offsetof(ngx_rbtree_node_t, color) + offsetof(ngx_http_limit_req_node_t, data) + key->len; ngx_http_limit_req_expire(ctx, 1); node = ngx_slab_alloc_locked(ctx->shpool, size); if (node == NULL) { ngx_http_limit_req_expire(ctx, 0); node = ngx_slab_alloc_locked(ctx->shpool, size); if (node == NULL) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, "could not allocate node%s", ctx->shpool->log_ctx); return NGX_ERROR; } } node->key = hash; lr = (ngx_http_limit_req_node_t *) &node->color; lr->len = (u_short) key->len; lr->excess = 0; ngx_memcpy(lr->data, key->data, key->len); ngx_rbtree_insert(&ctx->sh->rbtree, node); ngx_queue_insert_head(&ctx->sh->queue, &lr->queue); if (account) { lr->last = now; lr->count = 0; return NGX_OK; } lr->last = 0; lr->count = 1; ctx->node = lr; return NGX_AGAIN; } static ngx_msec_t ngx_http_limit_req_account(ngx_http_limit_req_limit_t *limits, ngx_uint_t n, ngx_uint_t *ep, ngx_http_limit_req_limit_t **limit) { ngx_int_t excess; ngx_msec_t now, delay, max_delay; ngx_msec_int_t ms; ngx_http_limit_req_ctx_t *ctx; ngx_http_limit_req_node_t *lr; excess = *ep; if (excess == 0 || (*limit)->nodelay) { max_delay = 0; } else { ctx = (*limit)->shm_zone->data; max_delay = excess * 1000 / ctx->rate; } while (n--) { ctx = limits[n].shm_zone->data; lr = ctx->node; if (lr == NULL) { continue; } ngx_shmtx_lock(&ctx->shpool->mutex); now = ngx_current_msec; ms = (ngx_msec_int_t) (now - lr->last); if (ms < -60000) { ms = 1; } else if (ms < 0) { ms = 0; } excess = lr->excess - ctx->rate * ms / 1000 + 1000; if (excess < 0) { excess = 0; } if (ms) { lr->last = now; } lr->excess = excess; lr->count--; ngx_shmtx_unlock(&ctx->shpool->mutex); ctx->node = NULL; if (limits[n].nodelay) { continue; } delay = excess * 1000 / ctx->rate; if (delay > max_delay) { max_delay = delay; *ep = excess; *limit = &limits[n]; } } return max_delay; } static void ngx_http_limit_req_expire(ngx_http_limit_req_ctx_t *ctx, ngx_uint_t n) { ngx_int_t excess; ngx_msec_t now; ngx_queue_t *q; ngx_msec_int_t ms; ngx_rbtree_node_t *node; ngx_http_limit_req_node_t *lr; now = ngx_current_msec; /* * n == 1 deletes one or two zero rate entries * n == 0 deletes oldest entry by force * and one or two zero rate entries */ while (n < 3) { if (ngx_queue_empty(&ctx->sh->queue)) { return; } q = ngx_queue_last(&ctx->sh->queue); lr = ngx_queue_data(q, ngx_http_limit_req_node_t, queue); if (lr->count) { /* * There is not much sense in looking further, * because we bump nodes on the lookup stage. */ return; } if (n++ != 0) { ms = (ngx_msec_int_t) (now - lr->last); ms = ngx_abs(ms); if (ms < 60000) { return; } excess = lr->excess - ctx->rate * ms / 1000; if (excess > 0) { return; } } ngx_queue_remove(q); node = (ngx_rbtree_node_t *) ((u_char *) lr - offsetof(ngx_rbtree_node_t, color)); ngx_rbtree_delete(&ctx->sh->rbtree, node); ngx_slab_free_locked(ctx->shpool, node); } } static ngx_int_t ngx_http_limit_req_init_zone(ngx_shm_zone_t *shm_zone, void *data) { ngx_http_limit_req_ctx_t *octx = data; size_t len; ngx_http_limit_req_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_req \"%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->sh = octx->sh; ctx->shpool = octx->shpool; return NGX_OK; } ctx->shpool = (ngx_slab_pool_t *) shm_zone->shm.addr; if (shm_zone->shm.exists) { ctx->sh = ctx->shpool->data; return NGX_OK; } ctx->sh = ngx_slab_alloc(ctx->shpool, sizeof(ngx_http_limit_req_shctx_t)); if (ctx->sh == NULL) { return NGX_ERROR; } ctx->shpool->data = ctx->sh; ngx_rbtree_init(&ctx->sh->rbtree, &ctx->sh->sentinel, ngx_http_limit_req_rbtree_insert_value); ngx_queue_init(&ctx->sh->queue); len = sizeof(" in limit_req zone \"\"") + shm_zone->shm.name.len; ctx->shpool->log_ctx = ngx_slab_alloc(ctx->shpool, len); if (ctx->shpool->log_ctx == NULL) { return NGX_ERROR; } ngx_sprintf(ctx->shpool->log_ctx, " in limit_req zone \"%V\"%Z", &shm_zone->shm.name); ctx->shpool->log_nomem = 0; return NGX_OK; } static void * ngx_http_limit_req_create_conf(ngx_conf_t *cf) { ngx_http_limit_req_conf_t *conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_limit_req_conf_t)); if (conf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->limits.elts = NULL; */ conf->limit_log_level = NGX_CONF_UNSET_UINT; conf->status_code = NGX_CONF_UNSET_UINT; return conf; } static char * ngx_http_limit_req_merge_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_limit_req_conf_t *prev = parent; ngx_http_limit_req_conf_t *conf = child; if (conf->limits.elts == NULL) { conf->limits = prev->limits; } ngx_conf_merge_uint_value(conf->limit_log_level, prev->limit_log_level, NGX_LOG_ERR); conf->delay_log_level = (conf->limit_log_level == NGX_LOG_INFO) ? NGX_LOG_INFO : conf->limit_log_level + 1; ngx_conf_merge_uint_value(conf->status_code, prev->status_code, NGX_HTTP_SERVICE_UNAVAILABLE); return NGX_CONF_OK; } static char * ngx_http_limit_req_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { u_char *p; size_t len; ssize_t size; ngx_str_t *value, name, s; ngx_int_t rate, scale; ngx_uint_t i; ngx_shm_zone_t *shm_zone; ngx_http_limit_req_ctx_t *ctx; ngx_http_compile_complex_value_t ccv; value = cf->args->elts; ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_limit_req_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; rate = 1; scale = 1; 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; } if (ngx_strncmp(value[i].data, "rate=", 5) == 0) { len = value[i].len; p = value[i].data + len - 3; if (ngx_strncmp(p, "r/s", 3) == 0) { scale = 1; len -= 3; } else if (ngx_strncmp(p, "r/m", 3) == 0) { scale = 60; len -= 3; } rate = ngx_atoi(value[i].data + 5, len - 5); if (rate <= 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid rate \"%V\"", &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; } ctx->rate = rate * 1000 / scale; shm_zone = ngx_shared_memory_add(cf, &name, size, &ngx_http_limit_req_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_req_init_zone; shm_zone->data = ctx; return NGX_CONF_OK; } static char * ngx_http_limit_req(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_limit_req_conf_t *lrcf = conf; ngx_int_t burst; ngx_str_t *value, s; ngx_uint_t i, nodelay; ngx_shm_zone_t *shm_zone; ngx_http_limit_req_limit_t *limit, *limits; value = cf->args->elts; shm_zone = NULL; burst = 0; nodelay = 0; for (i = 1; i < cf->args->nelts; i++) { if (ngx_strncmp(value[i].data, "zone=", 5) == 0) { s.len = value[i].len - 5; s.data = value[i].data + 5; shm_zone = ngx_shared_memory_add(cf, &s, 0, &ngx_http_limit_req_module); if (shm_zone == NULL) { return NGX_CONF_ERROR; } continue; } if (ngx_strncmp(value[i].data, "burst=", 6) == 0) { burst = ngx_atoi(value[i].data + 6, value[i].len - 6); if (burst <= 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid burst rate \"%V\"", &value[i]); return NGX_CONF_ERROR; } continue; } if (ngx_strcmp(value[i].data, "nodelay") == 0) { nodelay = 1; continue; } ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid parameter \"%V\"", &value[i]); return NGX_CONF_ERROR; } if (shm_zone == NULL) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "\"%V\" must have \"zone\" parameter", &cmd->name); return NGX_CONF_ERROR; } limits = lrcf->limits.elts; if (limits == NULL) { if (ngx_array_init(&lrcf->limits, cf->pool, 1, sizeof(ngx_http_limit_req_limit_t)) != NGX_OK) { return NGX_CONF_ERROR; } } for (i = 0; i < lrcf->limits.nelts; i++) { if (shm_zone == limits[i].shm_zone) { return "is duplicate"; } } limit = ngx_array_push(&lrcf->limits); if (limit == NULL) { return NGX_CONF_ERROR; } limit->shm_zone = shm_zone; limit->burst = burst * 1000; limit->nodelay = nodelay; return NGX_CONF_OK; } static ngx_int_t ngx_http_limit_req_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_req_handler; return NGX_OK; }