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view src/http/ngx_http_write_filter_module.c @ 9045:c6580dce98a8 quic

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QUIC: fixed triggering stream read event (ticket #2409). If a client packet carrying a stream data frame is not acked due to packet loss, the stream data is retransmitted later by client. It's also possible that the retransmitted range is bigger than before due to more stream data being available by then. If the original data was read out by the application, there would be no read event triggered by the retransmitted frame, even though it contains new data.
author Roman Arutyunyan <arut@nginx.com>
date Wed, 23 Nov 2022 18:50:26 +0400
parents ce6d9cf0f567
children
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 ngx_int_t ngx_http_write_filter_init(ngx_conf_t *cf);


static ngx_http_module_t  ngx_http_write_filter_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_write_filter_init,            /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    NULL,                                  /* create server configuration */
    NULL,                                  /* merge server configuration */

    NULL,                                  /* create location configuration */
    NULL,                                  /* merge location configuration */
};


ngx_module_t  ngx_http_write_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_write_filter_module_ctx,     /* module context */
    NULL,                                  /* 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
};


ngx_int_t
ngx_http_write_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    off_t                      size, sent, nsent, limit;
    ngx_uint_t                 last, flush, sync;
    ngx_msec_t                 delay;
    ngx_chain_t               *cl, *ln, **ll, *chain;
    ngx_connection_t          *c;
    ngx_http_core_loc_conf_t  *clcf;

    c = r->connection;

    if (c->error) {
        return NGX_ERROR;
    }

    size = 0;
    flush = 0;
    sync = 0;
    last = 0;
    ll = &r->out;

    /* find the size, the flush point and the last link of the saved chain */

    for (cl = r->out; cl; cl = cl->next) {
        ll = &cl->next;

        ngx_log_debug7(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "write 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);

        if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                          "zero size buf in writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary,
                          cl->buf->recycled,
                          cl->buf->in_file,
                          cl->buf->start,
                          cl->buf->pos,
                          cl->buf->last,
                          cl->buf->file,
                          cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();
            return NGX_ERROR;
        }

        if (ngx_buf_size(cl->buf) < 0) {
            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                          "negative size buf in writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary,
                          cl->buf->recycled,
                          cl->buf->in_file,
                          cl->buf->start,
                          cl->buf->pos,
                          cl->buf->last,
                          cl->buf->file,
                          cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();
            return NGX_ERROR;
        }

        size += ngx_buf_size(cl->buf);

        if (cl->buf->flush || cl->buf->recycled) {
            flush = 1;
        }

        if (cl->buf->sync) {
            sync = 1;
        }

        if (cl->buf->last_buf) {
            last = 1;
        }
    }

    /* add the new chain to the existent one */

    for (ln = in; ln; ln = ln->next) {
        cl = ngx_alloc_chain_link(r->pool);
        if (cl == NULL) {
            return NGX_ERROR;
        }

        cl->buf = ln->buf;
        *ll = cl;
        ll = &cl->next;

        ngx_log_debug7(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "write 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);

        if (ngx_buf_size(cl->buf) == 0 && !ngx_buf_special(cl->buf)) {
            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                          "zero size buf in writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary,
                          cl->buf->recycled,
                          cl->buf->in_file,
                          cl->buf->start,
                          cl->buf->pos,
                          cl->buf->last,
                          cl->buf->file,
                          cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();
            return NGX_ERROR;
        }

        if (ngx_buf_size(cl->buf) < 0) {
            ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                          "negative size buf in writer "
                          "t:%d r:%d f:%d %p %p-%p %p %O-%O",
                          cl->buf->temporary,
                          cl->buf->recycled,
                          cl->buf->in_file,
                          cl->buf->start,
                          cl->buf->pos,
                          cl->buf->last,
                          cl->buf->file,
                          cl->buf->file_pos,
                          cl->buf->file_last);

            ngx_debug_point();
            return NGX_ERROR;
        }

        size += ngx_buf_size(cl->buf);

        if (cl->buf->flush || cl->buf->recycled) {
            flush = 1;
        }

        if (cl->buf->sync) {
            sync = 1;
        }

        if (cl->buf->last_buf) {
            last = 1;
        }
    }

    *ll = NULL;

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http write filter: l:%ui f:%ui s:%O", last, flush, size);

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    /*
     * avoid the output if there are no last buf, no flush point,
     * there are the incoming bufs and the size of all bufs
     * is smaller than "postpone_output" directive
     */

    if (!last && !flush && in && size < (off_t) clcf->postpone_output) {
        return NGX_OK;
    }

    if (c->write->delayed) {
        c->buffered |= NGX_HTTP_WRITE_BUFFERED;
        return NGX_AGAIN;
    }

    if (size == 0
        && !(c->buffered & NGX_LOWLEVEL_BUFFERED)
        && !(last && c->need_last_buf)
        && !(flush && c->need_flush_buf))
    {
        if (last || flush || sync) {
            for (cl = r->out; cl; /* void */) {
                ln = cl;
                cl = cl->next;
                ngx_free_chain(r->pool, ln);
            }

            r->out = NULL;
            c->buffered &= ~NGX_HTTP_WRITE_BUFFERED;

            if (last) {
                r->response_sent = 1;
            }

            return NGX_OK;
        }

        ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                      "the http output chain is empty");

        ngx_debug_point();

        return NGX_ERROR;
    }

    if (!r->limit_rate_set) {
        r->limit_rate = ngx_http_complex_value_size(r, clcf->limit_rate, 0);
        r->limit_rate_set = 1;
    }

    if (r->limit_rate) {

        if (!r->limit_rate_after_set) {
            r->limit_rate_after = ngx_http_complex_value_size(r,
                                                    clcf->limit_rate_after, 0);
            r->limit_rate_after_set = 1;
        }

        limit = (off_t) r->limit_rate * (ngx_time() - r->start_sec + 1)
                - (c->sent - r->limit_rate_after);

        if (limit <= 0) {
            c->write->delayed = 1;
            delay = (ngx_msec_t) (- limit * 1000 / r->limit_rate + 1);
            ngx_add_timer(c->write, delay);

            c->buffered |= NGX_HTTP_WRITE_BUFFERED;

            return NGX_AGAIN;
        }

        if (clcf->sendfile_max_chunk
            && (off_t) clcf->sendfile_max_chunk < limit)
        {
            limit = clcf->sendfile_max_chunk;
        }

    } else {
        limit = clcf->sendfile_max_chunk;
    }

    sent = c->sent;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http write filter limit %O", limit);

    chain = c->send_chain(c, r->out, limit);

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                   "http write filter %p", chain);

    if (chain == NGX_CHAIN_ERROR) {
        c->error = 1;
        return NGX_ERROR;
    }

    if (r->limit_rate) {

        nsent = c->sent;

        if (r->limit_rate_after) {

            sent -= r->limit_rate_after;
            if (sent < 0) {
                sent = 0;
            }

            nsent -= r->limit_rate_after;
            if (nsent < 0) {
                nsent = 0;
            }
        }

        delay = (ngx_msec_t) ((nsent - sent) * 1000 / r->limit_rate);

        if (delay > 0) {
            c->write->delayed = 1;
            ngx_add_timer(c->write, delay);
        }
    }

    if (chain && c->write->ready && !c->write->delayed) {
        ngx_post_event(c->write, &ngx_posted_next_events);
    }

    for (cl = r->out; cl && cl != chain; /* void */) {
        ln = cl;
        cl = cl->next;
        ngx_free_chain(r->pool, ln);
    }

    r->out = chain;

    if (chain) {
        c->buffered |= NGX_HTTP_WRITE_BUFFERED;
        return NGX_AGAIN;
    }

    c->buffered &= ~NGX_HTTP_WRITE_BUFFERED;

    if (last) {
        r->response_sent = 1;
    }

    if ((c->buffered & NGX_LOWLEVEL_BUFFERED) && r->postponed == NULL) {
        return NGX_AGAIN;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_write_filter_init(ngx_conf_t *cf)
{
    ngx_http_top_body_filter = ngx_http_write_filter;

    return NGX_OK;
}