/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include "httpd.h" #include "http_config.h" #include "http_log.h" #include "util_filter.h" #include "mod_ratelimit.h" #define RATE_LIMIT_FILTER_NAME "RATE_LIMIT" #define RATE_INTERVAL_MS (200) typedef enum rl_state_e { RATE_LIMIT, RATE_FULLSPEED } rl_state_e; typedef struct rl_ctx_t { int speed; int chunk_size; int burst; int do_sleep; rl_state_e state; apr_bucket_brigade *tmpbb; apr_bucket_brigade *holdingbb; } rl_ctx_t; #if defined(RLFDEBUG) static void brigade_dump(request_rec *r, apr_bucket_brigade *bb) { apr_bucket *e; int i = 0; for (e = APR_BRIGADE_FIRST(bb); e != APR_BRIGADE_SENTINEL(bb); e = APR_BUCKET_NEXT(e), i++) { ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(03193) "brigade: [%d] %s", i, e->type->name); } } #endif /* RLFDEBUG */ static apr_status_t rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *bb) { apr_status_t rv = APR_SUCCESS; rl_ctx_t *ctx = f->ctx; apr_bucket_alloc_t *ba = f->r->connection->bucket_alloc; /* Set up our rl_ctx_t on first use */ if (ctx == NULL) { const char *rl = NULL; int ratelimit; int burst = 0; /* no subrequests. */ if (f->r->main != NULL) { ap_remove_output_filter(f); return ap_pass_brigade(f->next, bb); } /* Configuration: rate limit */ rl = apr_table_get(f->r->subprocess_env, "rate-limit"); if (rl == NULL) { ap_remove_output_filter(f); return ap_pass_brigade(f->next, bb); } /* rl is in kilo bytes / second */ ratelimit = atoi(rl) * 1024; if (ratelimit <= 0) { /* remove ourselves */ ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, f->r, APLOGNO(03488) "rl: disabling: rate-limit = %s (too high?)", rl); ap_remove_output_filter(f); return ap_pass_brigade(f->next, bb); } /* Configuration: optional initial burst */ rl = apr_table_get(f->r->subprocess_env, "rate-initial-burst"); if (rl != NULL) { burst = atoi(rl) * 1024; if (burst <= 0) { ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, f->r, APLOGNO(03489) "rl: disabling burst: rate-initial-burst = %s (too high?)", rl); burst = 0; } } /* Set up our context */ ctx = apr_palloc(f->r->pool, sizeof(rl_ctx_t)); f->ctx = ctx; ctx->state = RATE_LIMIT; ctx->speed = ratelimit; ctx->burst = burst; ctx->do_sleep = 0; /* calculate how many bytes / interval we want to send */ /* speed is bytes / second, so, how many (speed / 1000 % interval) */ ctx->chunk_size = (ctx->speed / (1000 / RATE_INTERVAL_MS)); ctx->tmpbb = apr_brigade_create(f->r->pool, ba); ctx->holdingbb = apr_brigade_create(f->r->pool, ba); } else { APR_BRIGADE_PREPEND(bb, ctx->holdingbb); } while (!APR_BRIGADE_EMPTY(bb)) { apr_bucket *e; if (ctx->state == RATE_FULLSPEED) { /* Find where we 'stop' going full speed. */ for (e = APR_BRIGADE_FIRST(bb); e != APR_BRIGADE_SENTINEL(bb); e = APR_BUCKET_NEXT(e)) { if (AP_RL_BUCKET_IS_END(e)) { apr_brigade_split_ex(bb, e, ctx->holdingbb); ctx->state = RATE_LIMIT; break; } } e = apr_bucket_flush_create(ba); APR_BRIGADE_INSERT_TAIL(bb, e); rv = ap_pass_brigade(f->next, bb); apr_brigade_cleanup(bb); if (rv != APR_SUCCESS) { ap_log_rerror(APLOG_MARK, APLOG_TRACE1, rv, f->r, APLOGNO(01455) "rl: full speed brigade pass failed."); return rv; } } else { for (e = APR_BRIGADE_FIRST(bb); e != APR_BRIGADE_SENTINEL(bb); e = APR_BUCKET_NEXT(e)) { if (AP_RL_BUCKET_IS_START(e)) { apr_brigade_split_ex(bb, e, ctx->holdingbb); ctx->state = RATE_FULLSPEED; break; } } while (!APR_BRIGADE_EMPTY(bb)) { apr_off_t len = ctx->chunk_size + ctx->burst; APR_BRIGADE_CONCAT(ctx->tmpbb, bb); /* * Pull next chunk of data; the initial amount is our * burst allotment (if any) plus a chunk. All subsequent * iterations are just chunks with whatever remaining * burst amounts we have left (in case not done in the * first bucket). */ rv = apr_brigade_partition(ctx->tmpbb, len, &e); if (rv != APR_SUCCESS && rv != APR_INCOMPLETE) { ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, f->r, APLOGNO(01456) "rl: partition failed."); return rv; } /* Send next metadata now if any */ while (e != APR_BRIGADE_SENTINEL(ctx->tmpbb) && APR_BUCKET_IS_METADATA(e)) { e = APR_BUCKET_NEXT(e); } if (e != APR_BRIGADE_SENTINEL(ctx->tmpbb)) { apr_brigade_split_ex(ctx->tmpbb, e, bb); } else { apr_brigade_length(ctx->tmpbb, 1, &len); } /* * Adjust the burst amount depending on how much * we've done up to now. */ if (ctx->burst) { ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, f->r, APLOGNO(03485) "rl: burst %d; len %"APR_OFF_T_FMT, ctx->burst, len); if (len < ctx->burst) { ctx->burst -= len; } else { ctx->burst = 0; } } e = APR_BRIGADE_LAST(ctx->tmpbb); if (APR_BUCKET_IS_EOS(e)) { ap_remove_output_filter(f); } else if (!APR_BUCKET_IS_FLUSH(e)) { if (APR_BRIGADE_EMPTY(bb)) { /* Wait for more (or next call) */ break; } e = apr_bucket_flush_create(ba); APR_BRIGADE_INSERT_TAIL(ctx->tmpbb, e); } #if defined(RLFDEBUG) brigade_dump(f->r, ctx->tmpbb); brigade_dump(f->r, bb); #endif /* RLFDEBUG */ if (ctx->do_sleep) { apr_sleep(RATE_INTERVAL_MS * 1000); } else { ctx->do_sleep = 1; } rv = ap_pass_brigade(f->next, ctx->tmpbb); apr_brigade_cleanup(ctx->tmpbb); if (rv != APR_SUCCESS) { /* Most often, user disconnects from stream */ ap_log_rerror(APLOG_MARK, APLOG_TRACE1, rv, f->r, APLOGNO(01457) "rl: brigade pass failed."); return rv; } } } if (!APR_BRIGADE_EMPTY(ctx->holdingbb)) { /* Any rate-limited data in tmpbb is sent unlimited along * with the rest. */ APR_BRIGADE_CONCAT(bb, ctx->tmpbb); APR_BRIGADE_CONCAT(bb, ctx->holdingbb); } } #if defined(RLFDEBUG) brigade_dump(f->r, ctx->tmpbb); #endif /* RLFDEBUG */ /* Save remaining tmpbb with the correct lifetime for the next call */ return ap_save_brigade(f, &ctx->holdingbb, &ctx->tmpbb, f->r->pool); } static apr_status_t rl_bucket_read(apr_bucket *b, const char **str, apr_size_t *len, apr_read_type_e block) { *str = NULL; *len = 0; return APR_SUCCESS; } AP_RL_DECLARE(apr_bucket *) ap_rl_end_create(apr_bucket_alloc_t *list) { apr_bucket *b = apr_bucket_alloc(sizeof(*b), list); APR_BUCKET_INIT(b); b->free = apr_bucket_free; b->list = list; b->length = 0; b->start = 0; b->data = NULL; b->type = &ap_rl_bucket_type_end; return b; } AP_RL_DECLARE(apr_bucket *) ap_rl_start_create(apr_bucket_alloc_t *list) { apr_bucket *b = apr_bucket_alloc(sizeof(*b), list); APR_BUCKET_INIT(b); b->free = apr_bucket_free; b->list = list; b->length = 0; b->start = 0; b->data = NULL; b->type = &ap_rl_bucket_type_start; return b; } AP_RL_DECLARE_DATA const apr_bucket_type_t ap_rl_bucket_type_end = { "RL_END", 5, APR_BUCKET_METADATA, apr_bucket_destroy_noop, rl_bucket_read, apr_bucket_setaside_noop, apr_bucket_split_notimpl, apr_bucket_simple_copy }; AP_RL_DECLARE_DATA const apr_bucket_type_t ap_rl_bucket_type_start = { "RL_START", 5, APR_BUCKET_METADATA, apr_bucket_destroy_noop, rl_bucket_read, apr_bucket_setaside_noop, apr_bucket_split_notimpl, apr_bucket_simple_copy }; static void register_hooks(apr_pool_t *p) { /* run after mod_deflate etc etc, but not at connection level, ie, mod_ssl. */ ap_register_output_filter(RATE_LIMIT_FILTER_NAME, rate_limit_filter, NULL, AP_FTYPE_CONNECTION - 1); } AP_DECLARE_MODULE(ratelimit) = { STANDARD20_MODULE_STUFF, NULL, /* create per-directory config structure */ NULL, /* merge per-directory config structures */ NULL, /* create per-server config structure */ NULL, /* merge per-server config structures */ NULL, /* command apr_table_t */ register_hooks };