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view src/http/ngx_http_request_body.c @ 6412:4ba91a4c66a3

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HTTP/2: implemented per request timeouts (closes #626). Previously, there were only three timeouts used globally for the whole HTTP/2 connection: 1. Idle timeout for inactivity when there are no streams in processing (the "http2_idle_timeout" directive); 2. Receive timeout for incomplete frames when there are no streams in processing (the "http2_recv_timeout" directive); 3. Send timeout when there are frames waiting in the output queue (the "send_timeout" directive on a server level). Reaching one of these timeouts leads to HTTP/2 connection close. This left a number of scenarios when a connection can get stuck without any processing and timeouts: 1. A client has sent the headers block partially so nginx starts processing a new stream but cannot continue without the rest of HEADERS and/or CONTINUATION frames; 2. When nginx waits for the request body; 3. All streams are stuck on exhausted connection or stream windows. The first idea that was rejected was to detect when the whole connection gets stuck because of these situations and set the global receive timeout. The disadvantage of such approach would be inconsistent behaviour in some typical use cases. For example, if a user never replies to the browser's question about where to save the downloaded file, the stream will be eventually closed by a timeout. On the other hand, this will not happen if there's some activity in other concurrent streams. Now almost all the request timeouts work like in HTTP/1.x connections, so the "client_header_timeout", "client_body_timeout", and "send_timeout" are respected. These timeouts close the request. The global timeouts work as before. Previously, the c->write->delayed flag was abused to avoid setting timeouts on stream events. Now, the "active" and "ready" flags are manipulated instead to control the processing of individual streams.
author Valentin Bartenev <vbart@nginx.com>
date Wed, 24 Feb 2016 15:58:07 +0300
parents 02abce4764b7
children 3b9fe734a76c
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


static void ngx_http_read_client_request_body_handler(ngx_http_request_t *r);
static ngx_int_t ngx_http_do_read_client_request_body(ngx_http_request_t *r);
static ngx_int_t ngx_http_write_request_body(ngx_http_request_t *r);
static ngx_int_t ngx_http_read_discarded_request_body(ngx_http_request_t *r);
static ngx_int_t ngx_http_discard_request_body_filter(ngx_http_request_t *r,
    ngx_buf_t *b);
static ngx_int_t ngx_http_test_expect(ngx_http_request_t *r);

static ngx_int_t ngx_http_request_body_filter(ngx_http_request_t *r,
    ngx_chain_t *in);
static ngx_int_t ngx_http_request_body_length_filter(ngx_http_request_t *r,
    ngx_chain_t *in);
static ngx_int_t ngx_http_request_body_chunked_filter(ngx_http_request_t *r,
    ngx_chain_t *in);


ngx_int_t
ngx_http_read_client_request_body(ngx_http_request_t *r,
    ngx_http_client_body_handler_pt post_handler)
{
    size_t                     preread;
    ssize_t                    size;
    ngx_int_t                  rc;
    ngx_buf_t                 *b;
    ngx_chain_t                out, *cl;
    ngx_http_request_body_t   *rb;
    ngx_http_core_loc_conf_t  *clcf;

    r->main->count++;

#if (NGX_HTTP_V2)
    if (r->stream && r == r->main) {
        r->request_body_no_buffering = 0;
        rc = ngx_http_v2_read_request_body(r, post_handler);
        goto done;
    }
#endif

    if (r != r->main || r->request_body || r->discard_body) {
        r->request_body_no_buffering = 0;
        post_handler(r);
        return NGX_OK;
    }

    if (ngx_http_test_expect(r) != NGX_OK) {
        rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
        goto done;
    }

    if (r->request_body_no_buffering) {
        r->request_body_in_file_only = 0;
    }

    rb = ngx_pcalloc(r->pool, sizeof(ngx_http_request_body_t));
    if (rb == NULL) {
        rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
        goto done;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     rb->bufs = NULL;
     *     rb->buf = NULL;
     *     rb->free = NULL;
     *     rb->busy = NULL;
     *     rb->chunked = NULL;
     */

    rb->rest = -1;
    rb->post_handler = post_handler;

    r->request_body = rb;

    if (r->headers_in.content_length_n < 0 && !r->headers_in.chunked) {
        r->request_body_no_buffering = 0;
        post_handler(r);
        return NGX_OK;
    }

    preread = r->header_in->last - r->header_in->pos;

    if (preread) {

        /* there is the pre-read part of the request body */

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http client request body preread %uz", preread);

        out.buf = r->header_in;
        out.next = NULL;

        rc = ngx_http_request_body_filter(r, &out);

        if (rc != NGX_OK) {
            goto done;
        }

        r->request_length += preread - (r->header_in->last - r->header_in->pos);

        if (!r->headers_in.chunked
            && rb->rest > 0
            && rb->rest <= (off_t) (r->header_in->end - r->header_in->last))
        {
            /* the whole request body may be placed in r->header_in */

            b = ngx_calloc_buf(r->pool);
            if (b == NULL) {
                rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
                goto done;
            }

            b->temporary = 1;
            b->start = r->header_in->pos;
            b->pos = r->header_in->pos;
            b->last = r->header_in->last;
            b->end = r->header_in->end;

            rb->buf = b;

            r->read_event_handler = ngx_http_read_client_request_body_handler;
            r->write_event_handler = ngx_http_request_empty_handler;

            rc = ngx_http_do_read_client_request_body(r);
            goto done;
        }

    } else {
        /* set rb->rest */

        if (ngx_http_request_body_filter(r, NULL) != NGX_OK) {
            rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
            goto done;
        }
    }

    if (rb->rest == 0) {
        /* the whole request body was pre-read */

        if (r->request_body_in_file_only) {
            if (ngx_http_write_request_body(r) != NGX_OK) {
                rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
                goto done;
            }

            if (rb->temp_file->file.offset != 0) {

                cl = ngx_chain_get_free_buf(r->pool, &rb->free);
                if (cl == NULL) {
                    rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
                    goto done;
                }

                b = cl->buf;

                ngx_memzero(b, sizeof(ngx_buf_t));

                b->in_file = 1;
                b->file_last = rb->temp_file->file.offset;
                b->file = &rb->temp_file->file;

                rb->bufs = cl;
            }
        }

        r->request_body_no_buffering = 0;

        post_handler(r);

        return NGX_OK;
    }

    if (rb->rest < 0) {
        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                      "negative request body rest");
        rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
        goto done;
    }

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    size = clcf->client_body_buffer_size;
    size += size >> 2;

    /* TODO: honor r->request_body_in_single_buf */

    if (!r->headers_in.chunked && rb->rest < size) {
        size = (ssize_t) rb->rest;

        if (r->request_body_in_single_buf) {
            size += preread;
        }

    } else {
        size = clcf->client_body_buffer_size;
    }

    rb->buf = ngx_create_temp_buf(r->pool, size);
    if (rb->buf == NULL) {
        rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
        goto done;
    }

    r->read_event_handler = ngx_http_read_client_request_body_handler;
    r->write_event_handler = ngx_http_request_empty_handler;

    rc = ngx_http_do_read_client_request_body(r);

done:

    if (r->request_body_no_buffering
        && (rc == NGX_OK || rc == NGX_AGAIN))
    {
        if (rc == NGX_OK) {
            r->request_body_no_buffering = 0;

        } else {
            /* rc == NGX_AGAIN */
            r->reading_body = 1;
        }

        r->read_event_handler = ngx_http_block_reading;
        post_handler(r);
    }

    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
        r->main->count--;
    }

    return rc;
}


ngx_int_t
ngx_http_read_unbuffered_request_body(ngx_http_request_t *r)
{
    ngx_int_t  rc;

    if (r->connection->read->timedout) {
        r->connection->timedout = 1;
        return NGX_HTTP_REQUEST_TIME_OUT;
    }

    rc = ngx_http_do_read_client_request_body(r);

    if (rc == NGX_OK) {
        r->reading_body = 0;
    }

    return rc;
}


static void
ngx_http_read_client_request_body_handler(ngx_http_request_t *r)
{
    ngx_int_t  rc;

    if (r->connection->read->timedout) {
        r->connection->timedout = 1;
        ngx_http_finalize_request(r, NGX_HTTP_REQUEST_TIME_OUT);
        return;
    }

    rc = ngx_http_do_read_client_request_body(r);

    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
        ngx_http_finalize_request(r, rc);
    }
}


static ngx_int_t
ngx_http_do_read_client_request_body(ngx_http_request_t *r)
{
    off_t                      rest;
    size_t                     size;
    ssize_t                    n;
    ngx_int_t                  rc;
    ngx_buf_t                 *b;
    ngx_chain_t               *cl, out;
    ngx_connection_t          *c;
    ngx_http_request_body_t   *rb;
    ngx_http_core_loc_conf_t  *clcf;

    c = r->connection;
    rb = r->request_body;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http read client request body");

    for ( ;; ) {
        for ( ;; ) {
            if (rb->buf->last == rb->buf->end) {

                if (rb->buf->pos != rb->buf->last) {

                    /* pass buffer to request body filter chain */

                    out.buf = rb->buf;
                    out.next = NULL;

                    rc = ngx_http_request_body_filter(r, &out);

                    if (rc != NGX_OK) {
                        return rc;
                    }

                } else {

                    /* update chains */

                    rc = ngx_http_request_body_filter(r, NULL);

                    if (rc != NGX_OK) {
                        return rc;
                    }
                }

                if (rb->busy != NULL) {
                    if (r->request_body_no_buffering) {
                        if (c->read->timer_set) {
                            ngx_del_timer(c->read);
                        }

                        if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
                            return NGX_HTTP_INTERNAL_SERVER_ERROR;
                        }

                        return NGX_AGAIN;
                    }

                    return NGX_HTTP_INTERNAL_SERVER_ERROR;
                }

                rb->buf->pos = rb->buf->start;
                rb->buf->last = rb->buf->start;
            }

            size = rb->buf->end - rb->buf->last;
            rest = rb->rest - (rb->buf->last - rb->buf->pos);

            if ((off_t) size > rest) {
                size = (size_t) rest;
            }

            n = c->recv(c, rb->buf->last, size);

            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                           "http client request body recv %z", n);

            if (n == NGX_AGAIN) {
                break;
            }

            if (n == 0) {
                ngx_log_error(NGX_LOG_INFO, c->log, 0,
                              "client prematurely closed connection");
            }

            if (n == 0 || n == NGX_ERROR) {
                c->error = 1;
                return NGX_HTTP_BAD_REQUEST;
            }

            rb->buf->last += n;
            r->request_length += n;

            if (n == rest) {
                /* pass buffer to request body filter chain */

                out.buf = rb->buf;
                out.next = NULL;

                rc = ngx_http_request_body_filter(r, &out);

                if (rc != NGX_OK) {
                    return rc;
                }
            }

            if (rb->rest == 0) {
                break;
            }

            if (rb->buf->last < rb->buf->end) {
                break;
            }
        }

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                       "http client request body rest %O", rb->rest);

        if (rb->rest == 0) {
            break;
        }

        if (!c->read->ready) {

            if (r->request_body_no_buffering
                && rb->buf->pos != rb->buf->last)
            {
                /* pass buffer to request body filter chain */

                out.buf = rb->buf;
                out.next = NULL;

                rc = ngx_http_request_body_filter(r, &out);

                if (rc != NGX_OK) {
                    return rc;
                }
            }

            clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
            ngx_add_timer(c->read, clcf->client_body_timeout);

            if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            return NGX_AGAIN;
        }
    }

    if (c->read->timer_set) {
        ngx_del_timer(c->read);
    }

    if (rb->temp_file || r->request_body_in_file_only) {

        /* save the last part */

        if (ngx_http_write_request_body(r) != NGX_OK) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        if (rb->temp_file->file.offset != 0) {

            cl = ngx_chain_get_free_buf(r->pool, &rb->free);
            if (cl == NULL) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            b = cl->buf;

            ngx_memzero(b, sizeof(ngx_buf_t));

            b->in_file = 1;
            b->file_last = rb->temp_file->file.offset;
            b->file = &rb->temp_file->file;

            rb->bufs = cl;
        }
    }

    if (!r->request_body_no_buffering) {
        r->read_event_handler = ngx_http_block_reading;
        rb->post_handler(r);
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_write_request_body(ngx_http_request_t *r)
{
    ssize_t                    n;
    ngx_chain_t               *cl, *ln;
    ngx_temp_file_t           *tf;
    ngx_http_request_body_t   *rb;
    ngx_http_core_loc_conf_t  *clcf;

    rb = r->request_body;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http write client request body, bufs %p", rb->bufs);

    if (rb->temp_file == NULL) {
        tf = ngx_pcalloc(r->pool, sizeof(ngx_temp_file_t));
        if (tf == NULL) {
            return NGX_ERROR;
        }

        clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

        tf->file.fd = NGX_INVALID_FILE;
        tf->file.log = r->connection->log;
        tf->path = clcf->client_body_temp_path;
        tf->pool = r->pool;
        tf->warn = "a client request body is buffered to a temporary file";
        tf->log_level = r->request_body_file_log_level;
        tf->persistent = r->request_body_in_persistent_file;
        tf->clean = r->request_body_in_clean_file;

        if (r->request_body_file_group_access) {
            tf->access = 0660;
        }

        rb->temp_file = tf;

        if (rb->bufs == NULL) {
            /* empty body with r->request_body_in_file_only */

            if (ngx_create_temp_file(&tf->file, tf->path, tf->pool,
                                     tf->persistent, tf->clean, tf->access)
                != NGX_OK)
            {
                return NGX_ERROR;
            }

            return NGX_OK;
        }
    }

    if (rb->bufs == NULL) {
        return NGX_OK;
    }

    n = ngx_write_chain_to_temp_file(rb->temp_file, rb->bufs);

    /* TODO: n == 0 or not complete and level event */

    if (n == NGX_ERROR) {
        return NGX_ERROR;
    }

    rb->temp_file->offset += n;

    /* mark all buffers as written */

    for (cl = rb->bufs; cl; /* void */) {

        cl->buf->pos = cl->buf->last;

        ln = cl;
        cl = cl->next;
        ngx_free_chain(r->pool, ln);
    }

    rb->bufs = NULL;

    return NGX_OK;
}


ngx_int_t
ngx_http_discard_request_body(ngx_http_request_t *r)
{
    ssize_t       size;
    ngx_int_t     rc;
    ngx_event_t  *rev;

#if (NGX_HTTP_V2)
    if (r->stream && r == r->main) {
        r->stream->skip_data = NGX_HTTP_V2_DATA_DISCARD;
        return NGX_OK;
    }
#endif

    if (r != r->main || r->discard_body || r->request_body) {
        return NGX_OK;
    }

    if (ngx_http_test_expect(r) != NGX_OK) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    rev = r->connection->read;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, rev->log, 0, "http set discard body");

    if (rev->timer_set) {
        ngx_del_timer(rev);
    }

    if (r->headers_in.content_length_n <= 0 && !r->headers_in.chunked) {
        return NGX_OK;
    }

    size = r->header_in->last - r->header_in->pos;

    if (size || r->headers_in.chunked) {
        rc = ngx_http_discard_request_body_filter(r, r->header_in);

        if (rc != NGX_OK) {
            return rc;
        }

        if (r->headers_in.content_length_n == 0) {
            return NGX_OK;
        }
    }

    rc = ngx_http_read_discarded_request_body(r);

    if (rc == NGX_OK) {
        r->lingering_close = 0;
        return NGX_OK;
    }

    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
        return rc;
    }

    /* rc == NGX_AGAIN */

    r->read_event_handler = ngx_http_discarded_request_body_handler;

    if (ngx_handle_read_event(rev, 0) != NGX_OK) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    r->count++;
    r->discard_body = 1;

    return NGX_OK;
}


void
ngx_http_discarded_request_body_handler(ngx_http_request_t *r)
{
    ngx_int_t                  rc;
    ngx_msec_t                 timer;
    ngx_event_t               *rev;
    ngx_connection_t          *c;
    ngx_http_core_loc_conf_t  *clcf;

    c = r->connection;
    rev = c->read;

    if (rev->timedout) {
        c->timedout = 1;
        c->error = 1;
        ngx_http_finalize_request(r, NGX_ERROR);
        return;
    }

    if (r->lingering_time) {
        timer = (ngx_msec_t) r->lingering_time - (ngx_msec_t) ngx_time();

        if ((ngx_msec_int_t) timer <= 0) {
            r->discard_body = 0;
            r->lingering_close = 0;
            ngx_http_finalize_request(r, NGX_ERROR);
            return;
        }

    } else {
        timer = 0;
    }

    rc = ngx_http_read_discarded_request_body(r);

    if (rc == NGX_OK) {
        r->discard_body = 0;
        r->lingering_close = 0;
        ngx_http_finalize_request(r, NGX_DONE);
        return;
    }

    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
        c->error = 1;
        ngx_http_finalize_request(r, NGX_ERROR);
        return;
    }

    /* rc == NGX_AGAIN */

    if (ngx_handle_read_event(rev, 0) != NGX_OK) {
        c->error = 1;
        ngx_http_finalize_request(r, NGX_ERROR);
        return;
    }

    if (timer) {

        clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

        timer *= 1000;

        if (timer > clcf->lingering_timeout) {
            timer = clcf->lingering_timeout;
        }

        ngx_add_timer(rev, timer);
    }
}


static ngx_int_t
ngx_http_read_discarded_request_body(ngx_http_request_t *r)
{
    size_t     size;
    ssize_t    n;
    ngx_int_t  rc;
    ngx_buf_t  b;
    u_char     buffer[NGX_HTTP_DISCARD_BUFFER_SIZE];

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http read discarded body");

    ngx_memzero(&b, sizeof(ngx_buf_t));

    b.temporary = 1;

    for ( ;; ) {
        if (r->headers_in.content_length_n == 0) {
            r->read_event_handler = ngx_http_block_reading;
            return NGX_OK;
        }

        if (!r->connection->read->ready) {
            return NGX_AGAIN;
        }

        size = (size_t) ngx_min(r->headers_in.content_length_n,
                                NGX_HTTP_DISCARD_BUFFER_SIZE);

        n = r->connection->recv(r->connection, buffer, size);

        if (n == NGX_ERROR) {
            r->connection->error = 1;
            return NGX_OK;
        }

        if (n == NGX_AGAIN) {
            return NGX_AGAIN;
        }

        if (n == 0) {
            return NGX_OK;
        }

        b.pos = buffer;
        b.last = buffer + n;

        rc = ngx_http_discard_request_body_filter(r, &b);

        if (rc != NGX_OK) {
            return rc;
        }
    }
}


static ngx_int_t
ngx_http_discard_request_body_filter(ngx_http_request_t *r, ngx_buf_t *b)
{
    size_t                    size;
    ngx_int_t                 rc;
    ngx_http_request_body_t  *rb;

    if (r->headers_in.chunked) {

        rb = r->request_body;

        if (rb == NULL) {

            rb = ngx_pcalloc(r->pool, sizeof(ngx_http_request_body_t));
            if (rb == NULL) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            rb->chunked = ngx_pcalloc(r->pool, sizeof(ngx_http_chunked_t));
            if (rb->chunked == NULL) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            r->request_body = rb;
        }

        for ( ;; ) {

            rc = ngx_http_parse_chunked(r, b, rb->chunked);

            if (rc == NGX_OK) {

                /* a chunk has been parsed successfully */

                size = b->last - b->pos;

                if ((off_t) size > rb->chunked->size) {
                    b->pos += (size_t) rb->chunked->size;
                    rb->chunked->size = 0;

                } else {
                    rb->chunked->size -= size;
                    b->pos = b->last;
                }

                continue;
            }

            if (rc == NGX_DONE) {

                /* a whole response has been parsed successfully */

                r->headers_in.content_length_n = 0;
                break;
            }

            if (rc == NGX_AGAIN) {

                /* set amount of data we want to see next time */

                r->headers_in.content_length_n = rb->chunked->length;
                break;
            }

            /* invalid */

            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "client sent invalid chunked body");

            return NGX_HTTP_BAD_REQUEST;
        }

    } else {
        size = b->last - b->pos;

        if ((off_t) size > r->headers_in.content_length_n) {
            b->pos += (size_t) r->headers_in.content_length_n;
            r->headers_in.content_length_n = 0;

        } else {
            b->pos = b->last;
            r->headers_in.content_length_n -= size;
        }
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_test_expect(ngx_http_request_t *r)
{
    ngx_int_t   n;
    ngx_str_t  *expect;

    if (r->expect_tested
        || r->headers_in.expect == NULL
        || r->http_version < NGX_HTTP_VERSION_11)
    {
        return NGX_OK;
    }

    r->expect_tested = 1;

    expect = &r->headers_in.expect->value;

    if (expect->len != sizeof("100-continue") - 1
        || ngx_strncasecmp(expect->data, (u_char *) "100-continue",
                           sizeof("100-continue") - 1)
           != 0)
    {
        return NGX_OK;
    }

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "send 100 Continue");

    n = r->connection->send(r->connection,
                            (u_char *) "HTTP/1.1 100 Continue" CRLF CRLF,
                            sizeof("HTTP/1.1 100 Continue" CRLF CRLF) - 1);

    if (n == sizeof("HTTP/1.1 100 Continue" CRLF CRLF) - 1) {
        return NGX_OK;
    }

    /* we assume that such small packet should be send successfully */

    return NGX_ERROR;
}


static ngx_int_t
ngx_http_request_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    if (r->headers_in.chunked) {
        return ngx_http_request_body_chunked_filter(r, in);

    } else {
        return ngx_http_request_body_length_filter(r, in);
    }
}


static ngx_int_t
ngx_http_request_body_length_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    size_t                     size;
    ngx_int_t                  rc;
    ngx_buf_t                 *b;
    ngx_chain_t               *cl, *tl, *out, **ll;
    ngx_http_request_body_t   *rb;

    rb = r->request_body;

    if (rb->rest == -1) {
        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http request body content length filter");

        rb->rest = r->headers_in.content_length_n;
    }

    out = NULL;
    ll = &out;

    for (cl = in; cl; cl = cl->next) {

        if (rb->rest == 0) {
            break;
        }

        tl = ngx_chain_get_free_buf(r->pool, &rb->free);
        if (tl == NULL) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        b = tl->buf;

        ngx_memzero(b, sizeof(ngx_buf_t));

        b->temporary = 1;
        b->tag = (ngx_buf_tag_t) &ngx_http_read_client_request_body;
        b->start = cl->buf->pos;
        b->pos = cl->buf->pos;
        b->last = cl->buf->last;
        b->end = cl->buf->end;
        b->flush = r->request_body_no_buffering;

        size = cl->buf->last - cl->buf->pos;

        if ((off_t) size < rb->rest) {
            cl->buf->pos = cl->buf->last;
            rb->rest -= size;

        } else {
            cl->buf->pos += (size_t) rb->rest;
            rb->rest = 0;
            b->last = cl->buf->pos;
            b->last_buf = 1;
        }

        *ll = tl;
        ll = &tl->next;
    }

    rc = ngx_http_top_request_body_filter(r, out);

    ngx_chain_update_chains(r->pool, &rb->free, &rb->busy, &out,
                            (ngx_buf_tag_t) &ngx_http_read_client_request_body);

    return rc;
}


static ngx_int_t
ngx_http_request_body_chunked_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    size_t                     size;
    ngx_int_t                  rc;
    ngx_buf_t                 *b;
    ngx_chain_t               *cl, *out, *tl, **ll;
    ngx_http_request_body_t   *rb;
    ngx_http_core_loc_conf_t  *clcf;

    rb = r->request_body;

    if (rb->rest == -1) {

        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http request body chunked filter");

        rb->chunked = ngx_pcalloc(r->pool, sizeof(ngx_http_chunked_t));
        if (rb->chunked == NULL) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        r->headers_in.content_length_n = 0;
        rb->rest = 3;
    }

    out = NULL;
    ll = &out;

    for (cl = in; cl; cl = cl->next) {

        for ( ;; ) {

            ngx_log_debug7(NGX_LOG_DEBUG_EVENT, r->connection->log, 0,
                           "http body chunked buf "
                           "t:%d f:%d %p, pos %p, size: %z file: %O, size: %O",
                           cl->buf->temporary, cl->buf->in_file,
                           cl->buf->start, cl->buf->pos,
                           cl->buf->last - cl->buf->pos,
                           cl->buf->file_pos,
                           cl->buf->file_last - cl->buf->file_pos);

            rc = ngx_http_parse_chunked(r, cl->buf, rb->chunked);

            if (rc == NGX_OK) {

                /* a chunk has been parsed successfully */

                clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

                if (clcf->client_max_body_size
                    && clcf->client_max_body_size
                       - r->headers_in.content_length_n < rb->chunked->size)
                {
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "client intended to send too large chunked "
                                  "body: %O+%O bytes",
                                  r->headers_in.content_length_n,
                                  rb->chunked->size);

                    r->lingering_close = 1;

                    return NGX_HTTP_REQUEST_ENTITY_TOO_LARGE;
                }

                tl = ngx_chain_get_free_buf(r->pool, &rb->free);
                if (tl == NULL) {
                    return NGX_HTTP_INTERNAL_SERVER_ERROR;
                }

                b = tl->buf;

                ngx_memzero(b, sizeof(ngx_buf_t));

                b->temporary = 1;
                b->tag = (ngx_buf_tag_t) &ngx_http_read_client_request_body;
                b->start = cl->buf->pos;
                b->pos = cl->buf->pos;
                b->last = cl->buf->last;
                b->end = cl->buf->end;
                b->flush = r->request_body_no_buffering;

                *ll = tl;
                ll = &tl->next;

                size = cl->buf->last - cl->buf->pos;

                if ((off_t) size > rb->chunked->size) {
                    cl->buf->pos += (size_t) rb->chunked->size;
                    r->headers_in.content_length_n += rb->chunked->size;
                    rb->chunked->size = 0;

                } else {
                    rb->chunked->size -= size;
                    r->headers_in.content_length_n += size;
                    cl->buf->pos = cl->buf->last;
                }

                b->last = cl->buf->pos;

                continue;
            }

            if (rc == NGX_DONE) {

                /* a whole response has been parsed successfully */

                rb->rest = 0;

                tl = ngx_chain_get_free_buf(r->pool, &rb->free);
                if (tl == NULL) {
                    return NGX_HTTP_INTERNAL_SERVER_ERROR;
                }

                b = tl->buf;

                ngx_memzero(b, sizeof(ngx_buf_t));

                b->last_buf = 1;

                *ll = tl;
                ll = &tl->next;

                break;
            }

            if (rc == NGX_AGAIN) {

                /* set rb->rest, amount of data we want to see next time */

                rb->rest = rb->chunked->length;

                break;
            }

            /* invalid */

            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "client sent invalid chunked body");

            return NGX_HTTP_BAD_REQUEST;
        }
    }

    rc = ngx_http_top_request_body_filter(r, out);

    ngx_chain_update_chains(r->pool, &rb->free, &rb->busy, &out,
                            (ngx_buf_tag_t) &ngx_http_read_client_request_body);

    return rc;
}


ngx_int_t
ngx_http_request_body_save_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
#if (NGX_DEBUG)
    ngx_chain_t               *cl;
#endif
    ngx_http_request_body_t   *rb;

    rb = r->request_body;

#if (NGX_DEBUG)

    for (cl = rb->bufs; cl; cl = cl->next) {
        ngx_log_debug7(NGX_LOG_DEBUG_EVENT, r->connection->log, 0,
                       "http body old buf t:%d f:%d %p, pos %p, size: %z "
                       "file: %O, size: %O",
                       cl->buf->temporary, cl->buf->in_file,
                       cl->buf->start, cl->buf->pos,
                       cl->buf->last - cl->buf->pos,
                       cl->buf->file_pos,
                       cl->buf->file_last - cl->buf->file_pos);
    }

    for (cl = in; cl; cl = cl->next) {
        ngx_log_debug7(NGX_LOG_DEBUG_EVENT, r->connection->log, 0,
                       "http body new buf t:%d f:%d %p, pos %p, size: %z "
                       "file: %O, size: %O",
                       cl->buf->temporary, cl->buf->in_file,
                       cl->buf->start, cl->buf->pos,
                       cl->buf->last - cl->buf->pos,
                       cl->buf->file_pos,
                       cl->buf->file_last - cl->buf->file_pos);
    }

#endif

    /* TODO: coalesce neighbouring buffers */

    if (ngx_chain_add_copy(r->pool, &rb->bufs, in) != NGX_OK) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    if (rb->rest > 0
        && rb->buf && rb->buf->last == rb->buf->end
        && !r->request_body_no_buffering)
    {
        if (ngx_http_write_request_body(r) != NGX_OK) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    }

    return NGX_OK;
}