modules/filters/mod_ratelimit.c

   1 /* Licensed to the Apache Software Foundation (ASF) under one or more
   2  * contributor license agreements.  See the NOTICE file distributed with
   3  * this work for additional information regarding copyright ownership.
   4  * The ASF licenses this file to You under the Apache License, Version 2.0
   5  * (the "License"); you may not use this file except in compliance with
   6  * the License.  You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include "httpd.h"
  18 #include "http_config.h"
  19 #include "http_log.h"
  20 #include "util_filter.h"
  21
  22 #include "mod_ratelimit.h"
  23
  24 #define RATE_LIMIT_FILTER_NAME "RATE_LIMIT"
  25 #define RATE_INTERVAL_MS (200)
  26
  27 typedef enum rl_state_e
  28 {
  29     RATE_ERROR,
  30     RATE_LIMIT,
  31     RATE_FULLSPEED
  32 } rl_state_e;
  33
  34 typedef struct rl_ctx_t
  35 {
  36     int speed;
  37     int chunk_size;
  38     rl_state_e state;
  39     apr_bucket_brigade *tmpbb;
  40     apr_bucket_brigade *holdingbb;
  41 } rl_ctx_t;
  42
  43 #if 0
  44 static void brigade_dump(request_rec *r, apr_bucket_brigade *bb)
  45 {
  46     apr_bucket *e;
  47     int i = 0;
  48
  49     for (e = APR_BRIGADE_FIRST(bb);
  50          e != APR_BRIGADE_SENTINEL(bb); e = APR_BUCKET_NEXT(e), i++) {
  51         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
  52                       "brigade: [%d] %s", i, e->type->name);
  53
  54     }
  55 }
  56 #endif
  57
  58 static apr_status_t
  59 rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)
  60 {
  61     apr_status_t rv = APR_SUCCESS;
  62     rl_ctx_t *ctx = f->ctx;
  63     apr_bucket *fb;
  64     int do_sleep = 0;
  65     apr_bucket_alloc_t *ba = f->r->connection->bucket_alloc;
  66     apr_bucket_brigade *bb = input_bb;
  67
  68     if (f->c->aborted) {
  69         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r, "rl: conn aborted");
  70         apr_brigade_cleanup(bb);
  71         return APR_ECONNABORTED;
  72     }
  73
  74     if (ctx == NULL) {
  75
  76         const char *rl = NULL;
  77
  78         /* no subrequests. */
  79         if (f->r->main != NULL) {
  80             ap_remove_output_filter(f);
  81             return ap_pass_brigade(f->next, bb);
  82         }
  83
  84         rl = apr_table_get(f->r->subprocess_env, "rate-limit");
  85
  86         if (rl == NULL) {
  87             ap_remove_output_filter(f);
  88             return ap_pass_brigade(f->next, bb);
  89         }
  90
  91         /* first run, init stuff */
  92         ctx = apr_palloc(f->r->pool, sizeof(rl_ctx_t));
  93         f->ctx = ctx;
  94         ctx->speed = 0;
  95         ctx->state = RATE_LIMIT;
  96
  97         /* rl is in kilo bytes / second  */
  98         ctx->speed = atoi(rl) * 1024;
  99
 100         if (ctx->speed == 0) {
 101             /* remove ourselves */
 102             ap_remove_output_filter(f);
 103             return ap_pass_brigade(f->next, bb);
 104         }
 105
 106         /* calculate how many bytes / interval we want to send */
 107         /* speed is bytes / second, so, how many  (speed / 1000 % interval) */
 108         ctx->chunk_size = (ctx->speed / (1000 / RATE_INTERVAL_MS));
 109         ctx->tmpbb = apr_brigade_create(f->r->pool, ba);
 110         ctx->holdingbb = apr_brigade_create(f->r->pool, ba);
 111     }
 112
 113     while (ctx->state != RATE_ERROR &&
 114            (!APR_BRIGADE_EMPTY(bb) || !APR_BRIGADE_EMPTY(ctx->holdingbb))) {
 115         apr_bucket *e;
 116
 117         if (!APR_BRIGADE_EMPTY(ctx->holdingbb)) {
 118             APR_BRIGADE_CONCAT(bb, ctx->holdingbb);
 119             apr_brigade_cleanup(ctx->holdingbb);
 120         }
 121
 122         while (ctx->state == RATE_FULLSPEED && !APR_BRIGADE_EMPTY(bb)) {
 123             /* Find where we 'stop' going full speed. */
 124             for (e = APR_BRIGADE_FIRST(bb);
 125                  e != APR_BRIGADE_SENTINEL(bb); e = APR_BUCKET_NEXT(e)) {
 126                 if (RL_BUCKET_IS_END(e)) {
 127                     apr_bucket *f;
 128                     f = APR_RING_LAST(&bb->list);
 129                     APR_RING_UNSPLICE(e, f, link);
 130                     APR_RING_SPLICE_TAIL(&ctx->holdingbb->list, e, f,
 131                                          apr_bucket, link);
 132                     ctx->state = RATE_LIMIT;
 133                     break;
 134                 }
 135             }
 136
 137             if (f->c->aborted) {
 138                 apr_brigade_cleanup(bb);
 139                 ctx->state = RATE_ERROR;
 140                 break;
 141             }
 142
 143             fb = apr_bucket_flush_create(ba);
 144             APR_BRIGADE_INSERT_TAIL(bb, fb);
 145             rv = ap_pass_brigade(f->next, bb);
 146
 147             if (rv != APR_SUCCESS) {
 148                 ctx->state = RATE_ERROR;
 149                 ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, f->r,
 150                               "rl: full speed brigade pass failed.");
 151             }
 152         }
 153
 154         while (ctx->state == RATE_LIMIT && !APR_BRIGADE_EMPTY(bb)) {
 155             for (e = APR_BRIGADE_FIRST(bb);
 156                  e != APR_BRIGADE_SENTINEL(bb); e = APR_BUCKET_NEXT(e)) {
 157                 if (RL_BUCKET_IS_START(e)) {
 158                     apr_bucket *f;
 159                     f = APR_RING_LAST(&bb->list);
 160                     APR_RING_UNSPLICE(e, f, link);
 161                     APR_RING_SPLICE_TAIL(&ctx->holdingbb->list, e, f,
 162                                          apr_bucket, link);
 163                     ctx->state = RATE_FULLSPEED;
 164                     break;
 165                 }
 166             }
 167
 168             while (!APR_BRIGADE_EMPTY(bb)) {
 169                 apr_bucket *stop_point;
 170                 apr_off_t len = 0;
 171
 172                 if (f->c->aborted) {
 173                     apr_brigade_cleanup(bb);
 174                     ctx->state = RATE_ERROR;
 175                     break;
 176                 }
 177
 178                 if (do_sleep) {
 179                     apr_sleep(RATE_INTERVAL_MS * 1000);
 180                 }
 181                 else {
 182                     do_sleep = 1;
 183                 }
 184
 185                 apr_brigade_length(bb, 1, &len);
 186
 187                 rv = apr_brigade_partition(bb, ctx->chunk_size, &stop_point);
 188                 if (rv != APR_SUCCESS && rv != APR_INCOMPLETE) {
 189                     ctx->state = RATE_ERROR;
 190                     ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r,
 191                                   "rl: partition failed.");
 192                     break;
 193                 }
 194
 195                 if (stop_point != APR_BRIGADE_SENTINEL(bb)) {
 196                     apr_bucket *f;
 197                     apr_bucket *e = APR_BUCKET_PREV(stop_point);
 198                     f = APR_RING_FIRST(&bb->list);
 199                     APR_RING_UNSPLICE(f, e, link);
 200                     APR_RING_SPLICE_HEAD(&ctx->tmpbb->list, f, e, apr_bucket,
 201                                          link);
 202                 }
 203                 else {
 204                     APR_BRIGADE_CONCAT(ctx->tmpbb, bb);
 205                 }
 206
 207                 fb = apr_bucket_flush_create(ba);
 208
 209                 APR_BRIGADE_INSERT_TAIL(ctx->tmpbb, fb);
 210
 211 #if 0
 212                 brigade_dump(f->r, ctx->tmpbb);
 213                 brigade_dump(f->r, bb);
 214 #endif
 215
 216                 rv = ap_pass_brigade(f->next, ctx->tmpbb);
 217                 apr_brigade_cleanup(ctx->tmpbb);
 218
 219                 if (rv != APR_SUCCESS) {
 220                     ctx->state = RATE_ERROR;
 221                     ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r,
 222                                   "rl: brigade pass failed.");
 223                     break;
 224                 }
 225             }
 226         }
 227     }
 228
 229     return rv;
 230 }
 231
 232
 233 static apr_status_t
 234 rl_bucket_read(apr_bucket *b, const char **str,
 235                apr_size_t *len, apr_read_type_e block)
 236 {
 237     *str = NULL;
 238     *len = 0;
 239     return APR_SUCCESS;
 240 }
 241
 242 AP_DECLARE(apr_bucket *)
 243     rl_end_create(apr_bucket_alloc_t *list)
 244 {
 245     apr_bucket *b = apr_bucket_alloc(sizeof(*b), list);
 246
 247     APR_BUCKET_INIT(b);
 248     b->free = apr_bucket_free;
 249     b->list = list;
 250     b->length = 0;
 251     b->start = 0;
 252     b->data = NULL;
 253     b->type = &rl_bucket_type_end;
 254
 255     return b;
 256 }
 257
 258 AP_DECLARE(apr_bucket *)
 259     rl_start_create(apr_bucket_alloc_t *list)
 260 {
 261     apr_bucket *b = apr_bucket_alloc(sizeof(*b), list);
 262
 263     APR_BUCKET_INIT(b);
 264     b->free = apr_bucket_free;
 265     b->list = list;
 266     b->length = 0;
 267     b->start = 0;
 268     b->data = NULL;
 269     b->type = &rl_bucket_type_start;
 270
 271     return b;
 272 }
 273
 274
 275
 276 AP_DECLARE_DATA const apr_bucket_type_t rl_bucket_type_end = {
 277     "RL_END", 5, APR_BUCKET_METADATA,
 278     apr_bucket_destroy_noop,
 279     rl_bucket_read,
 280     apr_bucket_setaside_noop,
 281     apr_bucket_split_notimpl,
 282     apr_bucket_simple_copy
 283 };
 284
 285
 286 AP_DECLARE_DATA const apr_bucket_type_t rl_bucket_type_start = {
 287     "RL_START", 5, APR_BUCKET_METADATA,
 288     apr_bucket_destroy_noop,
 289     rl_bucket_read,
 290     apr_bucket_setaside_noop,
 291     apr_bucket_split_notimpl,
 292     apr_bucket_simple_copy
 293 };
 294
 295
 296
 297
 298 static void register_hooks(apr_pool_t *p)
 299 {
 300     /* run after mod_deflate etc etc, but not at connection level, ie, mod_ssl. */
 301     ap_register_output_filter(RATE_LIMIT_FILTER_NAME, rate_limit_filter,
 302                               NULL, AP_FTYPE_PROTOCOL + 3);
 303 }
 304
 305 module AP_MODULE_DECLARE_DATA ratelimit_module = {
 306     STANDARD20_MODULE_STUFF,
 307     NULL,                       /* create per-directory config structure */
 308     NULL,                       /* merge per-directory config structures */
 309     NULL,                       /* create per-server config structure */
 310     NULL,                       /* merge per-server config structures */
 311     NULL,                       /* command apr_table_t */
 312     register_hooks
 313 };