view src/os/unix/ngx_send.c @ 6428:545b5e4d83b2

Upstream: avoid closing client connection in edge case. If proxy_cache is enabled, and proxy_no_cache tests true, it was previously possible for the client connection to be closed after a 304. The fix is to recheck r->header_only after the final cacheability is determined, and end the request if no longer cacheable. Example configuration: proxy_cache foo; proxy_cache_bypass 1; proxy_no_cache 1; If a client sends If-None-Match, and the upstream server returns 200 with a matching ETag, no body should be returned to the client. At the start of ngx_http_upstream_send_response proxy_no_cache is not yet tested, thus cacheable is still 1 and downstream_error is set. However, by the time the downstream_error check is done in process_request, proxy_no_cache has been tested and cacheable is set to 0. The client connection is then closed, regardless of keepalive.
author Justin Li <jli.justinli@gmail.com>
date Tue, 08 Mar 2016 22:31:55 -0500
parents d620f497c50f
children f01ab2dbcfdc
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


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


ssize_t
ngx_unix_send(ngx_connection_t *c, u_char *buf, size_t size)
{
    ssize_t       n;
    ngx_err_t     err;
    ngx_event_t  *wev;

    wev = c->write;

#if (NGX_HAVE_KQUEUE)

    if ((ngx_event_flags & NGX_USE_KQUEUE_EVENT) && wev->pending_eof) {
        (void) ngx_connection_error(c, wev->kq_errno,
                               "kevent() reported about an closed connection");
        wev->error = 1;
        return NGX_ERROR;
    }

#endif

    for ( ;; ) {
        n = send(c->fd, buf, size, 0);

        ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "send: fd:%d %d of %d", c->fd, n, size);

        if (n > 0) {
            if (n < (ssize_t) size) {
                wev->ready = 0;
            }

            c->sent += n;

            return n;
        }

        err = ngx_socket_errno;

        if (n == 0) {
            ngx_log_error(NGX_LOG_ALERT, c->log, err, "send() returned zero");
            wev->ready = 0;
            return n;
        }

        if (err == NGX_EAGAIN || err == NGX_EINTR) {
            wev->ready = 0;

            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                           "send() not ready");

            if (err == NGX_EAGAIN) {
                return NGX_AGAIN;
            }

        } else {
            wev->error = 1;
            (void) ngx_connection_error(c, err, "send() failed");
            return NGX_ERROR;
        }
    }
}