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view src/http/ngx_http_write_filter_module.c @ 7680:39501ce97e29

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gRPC: generate error when response size is wrong. As long as the "Content-Length" header is given, we now make sure it exactly matches the size of the response. If it doesn't, the response is considered malformed and must not be forwarded (https://tools.ietf.org/html/rfc7540#section-8.1.2.6). While it is not really possible to "not forward" the response which is already being forwarded, we generate an error instead, which is the closest equivalent. Previous behaviour was to pass everything to the client, but this seems to be suboptimal and causes issues (ticket #1695). Also this directly contradicts HTTP/2 specification requirements. Note that the new behaviour for the gRPC proxy is more strict than that applied in other variants of proxying. This is intentional, as HTTP/2 specification requires us to do so, while in other types of proxying malformed responses from backends are well known and historically tolerated.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 06 Jul 2020 18:36:25 +0300
parents c19ca381b2e6
children 61e9c078ee3d 94daa42ff5ce
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))
    {
        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;

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

    if (limit
        && c->write->ready
        && c->sent - sent >= limit - (off_t) (2 * ngx_pagesize))
    {
        c->write->delayed = 1;
        ngx_add_timer(c->write, 1);
    }

    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 ((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;
}