Commit 31878ee9 authored by Yann Ylavic's avatar Yann Ylavic
Browse files

Merge r1833875 from trunk: 

mod_ratelimit: fix behavior with proxied content

mod_ratelimit works by splitting data in "chunks"
to send to the client, sleeping a predefined amount
of time between them (200ms). So for example,
a rate-limit 40 value would correspond to a chunk size
of 8192 bytes, flushed to the client every 200ms.

The idea works fine when httpd directly serves the
content, since the filter will be called once with
a single bucket brigade. In the context of a proxied
content though the filter is likely to be called multiple
times, with a bucket brigade size that corresponds to
the maximum allowed buffer size. If this value is lower
or higher than the chunk size, the filter will not
properly rate limit the data going to the client.

This patch solves the problem with two fix:
1) do_sleep is now stored in the ctx context struct,
   so if the filter is invoked multiple times it
   will still sleep when needed. For example, say
   that the chunk_size is 8192 and the bucket brigate
   len is 10240: the filter will flush 8192 bytes
   on the first invocation, sleep 200ms, flush the
   remaining bytes and then finish. The next invocation
   will do the same, clearly not leading to the
   correct "sleeping pattern".
2) The example above highlights also another issue:
   mod_ratelimit should  flush only chunk_size bytes
   at the time (I am now excluding the burst calculation
   from the picture), and buffer between invocations
   unless the brigade contains EOS.

The change has been tested with various scenarios and
it looks working as expected, but of course more
feedback/testing is welcome.

The original patch was written by me and then Yann
refactored the code to be more precise and efficient,
basically transforming an axe in a wonderful Japanese
katana sword, so credits to him for this work.

PR: 62362


Submitted by: elukey
Reviewed by: elukey, jim, ylavic


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1835168 13f79535-47bb-0310-9956-ffa450edef68
parent 70f11557

CHANGES

+3 −0
Original line number Diff line number Diff line 
                                                         -*- coding: utf-8 -*-

Changes with Apache 2.4.34



  *) mod_ratelimit: fix behavior when proxing content. PR 62362.

     [Luca Toscano, Yann Ylavic]



  *) core: Re-allow '_' (underscore) in hostnames.

     [Eric Covener]

docs/manual/mod/mod_ratelimit.xml

+4 −1
Original line number Diff line number Diff line
@@ -30,7 +30,10 @@ the document to validate. --> 
<status>Extension</status>

<sourcefile>mod_ratelimit.c</sourcefile>

<identifier>ratelimit_module</identifier>

<compatibility><code>rate-initial-burst</code> available in httpd 2.4.24 and later.</compatibility>

<compatibility>

    <code>rate-initial-burst</code> available in httpd 2.4.24 and later.

    Rate limiting proxied content does not work correctly up to httpd 2.4.33.

</compatibility>



<summary>

modules/filters/mod_ratelimit.c

+62 −77
Original line number Diff line number Diff line
@@ -26,7 +26,6 @@ 


typedef enum rl_state_e

{

    RATE_ERROR,

    RATE_LIMIT,

    RATE_FULLSPEED

} rl_state_e;
@@ -36,6 +35,7 @@ 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;
@@ -57,20 +57,11 @@ static void brigade_dump(request_rec *r, apr_bucket_brigade *bb) 
#endif /* RLFDEBUG */



static apr_status_t

rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb)

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 *fb;

    int do_sleep = 0;

    apr_bucket_alloc_t *ba = f->r->connection->bucket_alloc;

    apr_bucket_brigade *bb = input_bb;



    if (f->c->aborted) {

        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r, APLOGNO(01454) "rl: conn aborted");

        apr_brigade_cleanup(bb);

        return APR_ECONNABORTED;

    }



    /* Set up our rl_ctx_t on first use */

    if (ctx == NULL) {
@@ -120,6 +111,7 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb) 
        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) */
@@ -127,79 +119,49 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb) 
        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 (ctx->state != RATE_ERROR &&

           (!APR_BRIGADE_EMPTY(bb) || !APR_BRIGADE_EMPTY(ctx->holdingbb))) {

    while (!APR_BRIGADE_EMPTY(bb)) {

        apr_bucket *e;



        if (!APR_BRIGADE_EMPTY(ctx->holdingbb)) {

            APR_BRIGADE_CONCAT(bb, ctx->holdingbb);

        }



        while (ctx->state == RATE_FULLSPEED && !APR_BRIGADE_EMPTY(bb)) {

        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_bucket *f;

                    f = APR_RING_LAST(&bb->list);

                    APR_RING_UNSPLICE(e, f, link);

                    APR_RING_SPLICE_TAIL(&ctx->holdingbb->list, e, f,

                                         apr_bucket, link);

                    apr_brigade_split_ex(bb, e, ctx->holdingbb);

                    ctx->state = RATE_LIMIT;

                    break;

                }

            }



            if (f->c->aborted) {

                apr_brigade_cleanup(bb);

                ctx->state = RATE_ERROR;

                break;

            }



            fb = apr_bucket_flush_create(ba);

            APR_BRIGADE_INSERT_TAIL(bb, fb);

            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) {

                ctx->state = RATE_ERROR;

                ap_log_rerror(APLOG_MARK, APLOG_TRACE1, rv, f->r, APLOGNO(01455)

                              "rl: full speed brigade pass failed.");

                return rv;

            }

        }



        while (ctx->state == RATE_LIMIT && !APR_BRIGADE_EMPTY(bb)) {

        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_bucket *f;

                    f = APR_RING_LAST(&bb->list);

                    APR_RING_UNSPLICE(e, f, link);

                    APR_RING_SPLICE_TAIL(&ctx->holdingbb->list, e, f,

                                         apr_bucket, link);

                    apr_brigade_split_ex(bb, e, ctx->holdingbb);

                    ctx->state = RATE_FULLSPEED;

                    break;

                }

            }



            while (!APR_BRIGADE_EMPTY(bb)) {

                apr_bucket *stop_point;

                apr_off_t len = 0;



                if (f->c->aborted) {

                    apr_brigade_cleanup(bb);

                    ctx->state = RATE_ERROR;

                    break;

                }

                apr_off_t len = ctx->chunk_size + ctx->burst;



                if (do_sleep) {

                    apr_sleep(RATE_INTERVAL_MS * 1000);

                }

                else {

                    do_sleep = 1;

                }



                apr_brigade_length(bb, 1, &len);

                APR_BRIGADE_CONCAT(ctx->tmpbb, bb);



                /*

                 * Pull next chunk of data; the initial amount is our
@@ -208,38 +170,29 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb) 
                 * burst amounts we have left (in case not done in the

                 * first bucket).

                 */

                rv = apr_brigade_partition(bb,

                    ctx->chunk_size + ctx->burst, &stop_point);

                rv = apr_brigade_partition(ctx->tmpbb, len, &e);

                if (rv != APR_SUCCESS && rv != APR_INCOMPLETE) {

                    ctx->state = RATE_ERROR;

                    ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, f->r, APLOGNO(01456)

                                  "rl: partition failed.");

                    break;

                    return rv;

                }



                if (stop_point != APR_BRIGADE_SENTINEL(bb)) {

                    apr_bucket *f;

                    apr_bucket *e = APR_BUCKET_PREV(stop_point);

                    f = APR_RING_FIRST(&bb->list);

                    APR_RING_UNSPLICE(f, e, link);

                    APR_RING_SPLICE_HEAD(&ctx->tmpbb->list, f, e, apr_bucket,

                                         link);

                /* 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_CONCAT(ctx->tmpbb, bb);

                    apr_brigade_length(ctx->tmpbb, 1, &len);

                }



                fb = apr_bucket_flush_create(ba);



                APR_BRIGADE_INSERT_TAIL(ctx->tmpbb, fb);



                /*

                 * Adjust the burst amount depending on how much

                 * we've done up to now.

                 */

                if (ctx->burst) {

                    len = ctx->burst;

                    apr_brigade_length(ctx->tmpbb, 1, &len);

                    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) {
@@ -250,26 +203,58 @@ rate_limit_filter(ap_filter_t *f, apr_bucket_brigade *input_bb) 
                    }

                }



                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 */

                    ctx->state = RATE_ERROR;

                    ap_log_rerror(APLOG_MARK, APLOG_TRACE1, rv, f->r, APLOGNO(01457)

                                  "rl: brigade pass failed.");

                    break;

                    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);

        }

    }



    return rv;

#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);

}