view src/http/modules/ngx_http_not_modified_filter_module.c @ 6927:c36d160cd4e0

Access log: removed dead ev->timedout check in flush timer handler. The ev->timedout flag is set on first timer expiration, and never reset after it. Due to this the code to stop the timer when the timer was canceled never worked (except in a very specific time frame immediately after start), and the timer was always armed again. This essentially resulted in a buffer flush at the end of an event loop iteration. This behaviour actually seems to be better than just stopping the flush timer for the whole shutdown, so it is preserved as is instead of fixing the code to actually remove the timer. It will be further improved by upcoming changes to preserve cancelable timers if there are other timers blocking shutdown.
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 07 Mar 2017 18:51:12 +0300
parents 8b6fa4842133
children
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_http.h>


static ngx_uint_t ngx_http_test_if_unmodified(ngx_http_request_t *r);
static ngx_uint_t ngx_http_test_if_modified(ngx_http_request_t *r);
static ngx_uint_t ngx_http_test_if_match(ngx_http_request_t *r,
    ngx_table_elt_t *header, ngx_uint_t weak);
static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf);


static ngx_http_module_t  ngx_http_not_modified_filter_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_not_modified_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_not_modified_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_not_modified_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
};


static ngx_http_output_header_filter_pt  ngx_http_next_header_filter;


static ngx_int_t
ngx_http_not_modified_header_filter(ngx_http_request_t *r)
{
    if (r->headers_out.status != NGX_HTTP_OK
        || r != r->main
        || r->disable_not_modified)
    {
        return ngx_http_next_header_filter(r);
    }

    if (r->headers_in.if_unmodified_since
        && !ngx_http_test_if_unmodified(r))
    {
        return ngx_http_filter_finalize_request(r, NULL,
                                                NGX_HTTP_PRECONDITION_FAILED);
    }

    if (r->headers_in.if_match
        && !ngx_http_test_if_match(r, r->headers_in.if_match, 0))
    {
        return ngx_http_filter_finalize_request(r, NULL,
                                                NGX_HTTP_PRECONDITION_FAILED);
    }

    if (r->headers_in.if_modified_since || r->headers_in.if_none_match) {

        if (r->headers_in.if_modified_since
            && ngx_http_test_if_modified(r))
        {
            return ngx_http_next_header_filter(r);
        }

        if (r->headers_in.if_none_match
            && !ngx_http_test_if_match(r, r->headers_in.if_none_match, 1))
        {
            return ngx_http_next_header_filter(r);
        }

        /* not modified */

        r->headers_out.status = NGX_HTTP_NOT_MODIFIED;
        r->headers_out.status_line.len = 0;
        r->headers_out.content_type.len = 0;
        ngx_http_clear_content_length(r);
        ngx_http_clear_accept_ranges(r);

        if (r->headers_out.content_encoding) {
            r->headers_out.content_encoding->hash = 0;
            r->headers_out.content_encoding = NULL;
        }

        return ngx_http_next_header_filter(r);
    }

    return ngx_http_next_header_filter(r);
}


static ngx_uint_t
ngx_http_test_if_unmodified(ngx_http_request_t *r)
{
    time_t  iums;

    if (r->headers_out.last_modified_time == (time_t) -1) {
        return 0;
    }

    iums = ngx_parse_http_time(r->headers_in.if_unmodified_since->value.data,
                               r->headers_in.if_unmodified_since->value.len);

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "http iums:%T lm:%T", iums, r->headers_out.last_modified_time);

    if (iums >= r->headers_out.last_modified_time) {
        return 1;
    }

    return 0;
}


static ngx_uint_t
ngx_http_test_if_modified(ngx_http_request_t *r)
{
    time_t                     ims;
    ngx_http_core_loc_conf_t  *clcf;

    if (r->headers_out.last_modified_time == (time_t) -1) {
        return 1;
    }

    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) {
        return 1;
    }

    ims = ngx_parse_http_time(r->headers_in.if_modified_since->value.data,
                              r->headers_in.if_modified_since->value.len);

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http ims:%T lm:%T", ims, r->headers_out.last_modified_time);

    if (ims == r->headers_out.last_modified_time) {
        return 0;
    }

    if (clcf->if_modified_since == NGX_HTTP_IMS_EXACT
        || ims < r->headers_out.last_modified_time)
    {
        return 1;
    }

    return 0;
}


static ngx_uint_t
ngx_http_test_if_match(ngx_http_request_t *r, ngx_table_elt_t *header,
    ngx_uint_t weak)
{
    u_char     *start, *end, ch;
    ngx_str_t   etag, *list;

    list = &header->value;

    if (list->len == 1 && list->data[0] == '*') {
        return 1;
    }

    if (r->headers_out.etag == NULL) {
        return 0;
    }

    etag = r->headers_out.etag->value;

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http im:\"%V\" etag:%V", list, &etag);

    if (weak
        && etag.len > 2
        && etag.data[0] == 'W'
        && etag.data[1] == '/')
    {
        etag.len -= 2;
        etag.data += 2;
    }

    start = list->data;
    end = list->data + list->len;

    while (start < end) {

        if (weak
            && end - start > 2
            && start[0] == 'W'
            && start[1] == '/')
        {
            start += 2;
        }

        if (etag.len > (size_t) (end - start)) {
            return 0;
        }

        if (ngx_strncmp(start, etag.data, etag.len) != 0) {
            goto skip;
        }

        start += etag.len;

        while (start < end) {
            ch = *start;

            if (ch == ' ' || ch == '\t') {
                start++;
                continue;
            }

            break;
        }

        if (start == end || *start == ',') {
            return 1;
        }

    skip:

        while (start < end && *start != ',') { start++; }
        while (start < end) {
            ch = *start;

            if (ch == ' ' || ch == '\t' || ch == ',') {
                start++;
                continue;
            }

            break;
        }
    }

    return 0;
}


static ngx_int_t
ngx_http_not_modified_filter_init(ngx_conf_t *cf)
{
    ngx_http_next_header_filter = ngx_http_top_header_filter;
    ngx_http_top_header_filter = ngx_http_not_modified_header_filter;

    return NGX_OK;
}