Mercurial > hg > nginx

view src/http/modules/ngx_http_headers_filter_module.c @ 9203:0de20f43db25

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Fixed request termination with AIO and subrequests (ticket #2555). When a request was terminated due to an error via ngx_http_terminate_request() while an AIO operation was running in a subrequest, various issues were observed. This happened because ngx_http_request_finalizer() was only set in the subrequest where ngx_http_terminate_request() was called, but not in the subrequest where the AIO operation was running. After completion of the AIO operation normal processing of the subrequest was resumed, leading to issues. In particular, in case of the upstream module, termination of the request called upstream cleanup, which closed the upstream connection. Attempts to further work with the upstream connection after AIO operation completion resulted in segfaults in ngx_ssl_recv(), "readv() failed (9: Bad file descriptor) while reading upstream" errors, or socket leaks. In ticket #2555, issues were observed with the following configuration with cache background update (with thread writing instrumented to introduce a delay, when a client closes the connection during an update): location = /background-and-aio-write { proxy_pass ... proxy_cache one; proxy_cache_valid 200 1s; proxy_cache_background_update on; proxy_cache_use_stale updating; aio threads; aio_write on; limit_rate 1000; } Similarly, the same issue can be seen with SSI, and can be caused by errors in subrequests, such as in the following configuration (where "/proxy" uses AIO, and "/sleep" returns 444 after some delay, causing request termination): location = /ssi-active-boom { ssi on; ssi_types *; return 200 ' <!--#include virtual="/proxy" --> <!--#include virtual="/sleep" --> '; limit_rate 1000; } Or the same with both AIO operation and the error in non-active subrequests (which needs slightly different handling, see below): location = /ssi-non-active-boom { ssi on; ssi_types *; return 200 ' <!--#include virtual="/static" --> <!--#include virtual="/proxy" --> <!--#include virtual="/sleep" --> '; limit_rate 1000; } Similarly, issues can be observed with just static files. However, with static files potential impact is limited due to timeout safeguards in ngx_http_writer(), and the fact that c->error is set during request termination. In a simple configuration with an AIO operation in the active subrequest, such as in the following configuration, the connection is closed right after completion of the AIO operation anyway, since ngx_http_writer() tries to write to the connection and fails due to c->error set: location = /ssi-active-static-boom { ssi on; ssi_types *; return 200 ' <!--#include virtual="/static-aio" --> <!--#include virtual="/sleep" --> '; limit_rate 1000; } In the following configuration, with an AIO operation in a non-active subrequest, the connection is closed only after send_timeout expires: location = /ssi-non-active-static-boom { ssi on; ssi_types *; return 200 ' <!--#include virtual="/static" --> <!--#include virtual="/static-aio" --> <!--#include virtual="/sleep" --> '; limit_rate 1000; } Fix is to introduce r->main->terminated flag, which is to be checked by AIO event handlers when the r->main->blocked counter is decremented. When the flag is set, handlers are expected to wake up the connection instead of the subrequest (which might be already cleaned up). Additionally, now ngx_http_request_finalizer() is always set in the active subrequest, so waking up the connection properly finalizes the request even if termination happened in a non-active subrequest.
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 30 Jan 2024 03:20:05 +0300
parents e64a1f32065b
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>


typedef struct ngx_http_header_val_s  ngx_http_header_val_t;

typedef ngx_int_t (*ngx_http_set_header_pt)(ngx_http_request_t *r,
    ngx_http_header_val_t *hv, ngx_str_t *value);


typedef struct {
    ngx_str_t                  name;
    ngx_uint_t                 offset;
    ngx_http_set_header_pt     handler;
} ngx_http_set_header_t;


struct ngx_http_header_val_s {
    ngx_http_complex_value_t   value;
    ngx_str_t                  key;
    ngx_http_set_header_pt     handler;
    ngx_uint_t                 offset;
    ngx_uint_t                 always;  /* unsigned  always:1 */
};


typedef enum {
    NGX_HTTP_EXPIRES_OFF,
    NGX_HTTP_EXPIRES_EPOCH,
    NGX_HTTP_EXPIRES_MAX,
    NGX_HTTP_EXPIRES_ACCESS,
    NGX_HTTP_EXPIRES_MODIFIED,
    NGX_HTTP_EXPIRES_DAILY,
    NGX_HTTP_EXPIRES_UNSET
} ngx_http_expires_t;


typedef struct {
    ngx_http_expires_t         expires;
    time_t                     expires_time;
    ngx_http_complex_value_t  *expires_value;
    ngx_array_t               *headers;
    ngx_array_t               *trailers;
} ngx_http_headers_conf_t;


static ngx_int_t ngx_http_set_expires(ngx_http_request_t *r,
    ngx_http_headers_conf_t *conf);
static ngx_int_t ngx_http_parse_expires(ngx_str_t *value,
    ngx_http_expires_t *expires, time_t *expires_time, char **err);
static ngx_int_t ngx_http_add_multi_header_lines(ngx_http_request_t *r,
    ngx_http_header_val_t *hv, ngx_str_t *value);
static ngx_int_t ngx_http_add_header(ngx_http_request_t *r,
    ngx_http_header_val_t *hv, ngx_str_t *value);
static ngx_int_t ngx_http_set_last_modified(ngx_http_request_t *r,
    ngx_http_header_val_t *hv, ngx_str_t *value);
static ngx_int_t ngx_http_set_response_header(ngx_http_request_t *r,
    ngx_http_header_val_t *hv, ngx_str_t *value);

static void *ngx_http_headers_create_conf(ngx_conf_t *cf);
static char *ngx_http_headers_merge_conf(ngx_conf_t *cf,
    void *parent, void *child);
static ngx_int_t ngx_http_headers_filter_init(ngx_conf_t *cf);
static char *ngx_http_headers_expires(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_headers_add(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_http_set_header_t  ngx_http_set_headers[] = {

    { ngx_string("Cache-Control"),
                 offsetof(ngx_http_headers_out_t, cache_control),
                 ngx_http_add_multi_header_lines },

    { ngx_string("Link"),
                 offsetof(ngx_http_headers_out_t, link),
                 ngx_http_add_multi_header_lines },

    { ngx_string("Last-Modified"),
                 offsetof(ngx_http_headers_out_t, last_modified),
                 ngx_http_set_last_modified },

    { ngx_string("ETag"),
                 offsetof(ngx_http_headers_out_t, etag),
                 ngx_http_set_response_header },

    { ngx_null_string, 0, NULL }
};


static ngx_command_t  ngx_http_headers_filter_commands[] = {

    { ngx_string("expires"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
                        |NGX_CONF_TAKE12,
      ngx_http_headers_expires,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("add_header"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
                        |NGX_CONF_TAKE23,
      ngx_http_headers_add,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_headers_conf_t, headers),
      NULL },

    { ngx_string("add_trailer"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
                        |NGX_CONF_TAKE23,
      ngx_http_headers_add,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_headers_conf_t, trailers),
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_headers_filter_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_headers_filter_init,          /* postconfiguration */

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

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

    ngx_http_headers_create_conf,          /* create location configuration */
    ngx_http_headers_merge_conf            /* merge location configuration */
};


ngx_module_t  ngx_http_headers_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_headers_filter_module_ctx,   /* module context */
    ngx_http_headers_filter_commands,      /* 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_http_output_body_filter_pt    ngx_http_next_body_filter;


static ngx_int_t
ngx_http_headers_filter(ngx_http_request_t *r)
{
    ngx_str_t                 value;
    ngx_uint_t                i, safe_status;
    ngx_http_header_val_t    *h;
    ngx_http_headers_conf_t  *conf;

    if (r != r->main) {
        return ngx_http_next_header_filter(r);
    }

    conf = ngx_http_get_module_loc_conf(r, ngx_http_headers_filter_module);

    if (conf->expires == NGX_HTTP_EXPIRES_OFF
        && conf->headers == NULL
        && conf->trailers == NULL)
    {
        return ngx_http_next_header_filter(r);
    }

    switch (r->headers_out.status) {

    case NGX_HTTP_OK:
    case NGX_HTTP_CREATED:
    case NGX_HTTP_NO_CONTENT:
    case NGX_HTTP_PARTIAL_CONTENT:
    case NGX_HTTP_MOVED_PERMANENTLY:
    case NGX_HTTP_MOVED_TEMPORARILY:
    case NGX_HTTP_SEE_OTHER:
    case NGX_HTTP_NOT_MODIFIED:
    case NGX_HTTP_TEMPORARY_REDIRECT:
    case NGX_HTTP_PERMANENT_REDIRECT:
        safe_status = 1;
        break;

    default:
        safe_status = 0;
        break;
    }

    if (conf->expires != NGX_HTTP_EXPIRES_OFF && safe_status) {
        if (ngx_http_set_expires(r, conf) != NGX_OK) {
            return NGX_ERROR;
        }
    }

    if (conf->headers) {
        h = conf->headers->elts;
        for (i = 0; i < conf->headers->nelts; i++) {

            if (!safe_status && !h[i].always) {
                continue;
            }

            if (ngx_http_complex_value(r, &h[i].value, &value) != NGX_OK) {
                return NGX_ERROR;
            }

            if (h[i].handler(r, &h[i], &value) != NGX_OK) {
                return NGX_ERROR;
            }
        }
    }

    if (conf->trailers) {
        h = conf->trailers->elts;
        for (i = 0; i < conf->trailers->nelts; i++) {

            if (!safe_status && !h[i].always) {
                continue;
            }

            r->expect_trailers = 1;
            break;
        }
    }

    return ngx_http_next_header_filter(r);
}


static ngx_int_t
ngx_http_trailers_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    ngx_str_t                 value;
    ngx_uint_t                i, safe_status;
    ngx_chain_t              *cl;
    ngx_table_elt_t          *t;
    ngx_http_header_val_t    *h;
    ngx_http_headers_conf_t  *conf;

    conf = ngx_http_get_module_loc_conf(r, ngx_http_headers_filter_module);

    if (in == NULL
        || conf->trailers == NULL
        || !r->expect_trailers
        || r->header_only)
    {
        return ngx_http_next_body_filter(r, in);
    }

    for (cl = in; cl; cl = cl->next) {
        if (cl->buf->last_buf) {
            break;
        }
    }

    if (cl == NULL) {
        return ngx_http_next_body_filter(r, in);
    }

    switch (r->headers_out.status) {

    case NGX_HTTP_OK:
    case NGX_HTTP_CREATED:
    case NGX_HTTP_NO_CONTENT:
    case NGX_HTTP_PARTIAL_CONTENT:
    case NGX_HTTP_MOVED_PERMANENTLY:
    case NGX_HTTP_MOVED_TEMPORARILY:
    case NGX_HTTP_SEE_OTHER:
    case NGX_HTTP_NOT_MODIFIED:
    case NGX_HTTP_TEMPORARY_REDIRECT:
    case NGX_HTTP_PERMANENT_REDIRECT:
        safe_status = 1;
        break;

    default:
        safe_status = 0;
        break;
    }

    h = conf->trailers->elts;
    for (i = 0; i < conf->trailers->nelts; i++) {

        if (!safe_status && !h[i].always) {
            continue;
        }

        if (ngx_http_complex_value(r, &h[i].value, &value) != NGX_OK) {
            return NGX_ERROR;
        }

        if (value.len) {
            t = ngx_list_push(&r->headers_out.trailers);
            if (t == NULL) {
                return NGX_ERROR;
            }

            t->key = h[i].key;
            t->value = value;
            t->hash = 1;
        }
    }

    return ngx_http_next_body_filter(r, in);
}


static ngx_int_t
ngx_http_set_expires(ngx_http_request_t *r, ngx_http_headers_conf_t *conf)
{
    char                *err;
    size_t               len;
    time_t               now, expires_time, max_age;
    ngx_str_t            value;
    ngx_int_t            rc;
    ngx_table_elt_t     *e, *cc;
    ngx_http_expires_t   expires;

    expires = conf->expires;
    expires_time = conf->expires_time;

    if (conf->expires_value != NULL) {

        if (ngx_http_complex_value(r, conf->expires_value, &value) != NGX_OK) {
            return NGX_ERROR;
        }

        rc = ngx_http_parse_expires(&value, &expires, &expires_time, &err);

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

        if (expires == NGX_HTTP_EXPIRES_OFF) {
            return NGX_OK;
        }
    }

    e = r->headers_out.expires;

    if (e == NULL) {

        e = ngx_list_push(&r->headers_out.headers);
        if (e == NULL) {
            return NGX_ERROR;
        }

        r->headers_out.expires = e;
        e->next = NULL;

        e->hash = 1;
        ngx_str_set(&e->key, "Expires");
    }

    len = sizeof("Mon, 28 Sep 1970 06:00:00 GMT");
    e->value.len = len - 1;

    cc = r->headers_out.cache_control;

    if (cc == NULL) {

        cc = ngx_list_push(&r->headers_out.headers);
        if (cc == NULL) {
            e->hash = 0;
            return NGX_ERROR;
        }

        r->headers_out.cache_control = cc;
        cc->next = NULL;

        cc->hash = 1;
        ngx_str_set(&cc->key, "Cache-Control");

    } else {
        for (cc = cc->next; cc; cc = cc->next) {
            cc->hash = 0;
        }

        cc = r->headers_out.cache_control;
        cc->next = NULL;
    }

    if (expires == NGX_HTTP_EXPIRES_EPOCH) {
        e->value.data = (u_char *) "Thu, 01 Jan 1970 00:00:01 GMT";
        ngx_str_set(&cc->value, "no-cache");
        return NGX_OK;
    }

    if (expires == NGX_HTTP_EXPIRES_MAX) {
        e->value.data = (u_char *) "Thu, 31 Dec 2037 23:55:55 GMT";
        /* 10 years */
        ngx_str_set(&cc->value, "max-age=315360000");
        return NGX_OK;
    }

    e->value.data = ngx_pnalloc(r->pool, len);
    if (e->value.data == NULL) {
        e->hash = 0;
        cc->hash = 0;
        return NGX_ERROR;
    }

    if (expires_time == 0 && expires != NGX_HTTP_EXPIRES_DAILY) {
        ngx_memcpy(e->value.data, ngx_cached_http_time.data,
                   ngx_cached_http_time.len + 1);
        ngx_str_set(&cc->value, "max-age=0");
        return NGX_OK;
    }

    now = ngx_time();

    if (expires == NGX_HTTP_EXPIRES_DAILY) {
        expires_time = ngx_next_time(expires_time);
        max_age = expires_time - now;

    } else if (expires == NGX_HTTP_EXPIRES_ACCESS
               || r->headers_out.last_modified_time == -1)
    {
        max_age = expires_time;
        expires_time += now;

    } else {
        expires_time += r->headers_out.last_modified_time;
        max_age = expires_time - now;
    }

    ngx_http_time(e->value.data, expires_time);

    if (conf->expires_time < 0 || max_age < 0) {
        ngx_str_set(&cc->value, "no-cache");
        return NGX_OK;
    }

    cc->value.data = ngx_pnalloc(r->pool,
                                 sizeof("max-age=") + NGX_TIME_T_LEN + 1);
    if (cc->value.data == NULL) {
        cc->hash = 0;
        return NGX_ERROR;
    }

    cc->value.len = ngx_sprintf(cc->value.data, "max-age=%T", max_age)
                    - cc->value.data;

    return NGX_OK;
}


static ngx_int_t
ngx_http_parse_expires(ngx_str_t *value, ngx_http_expires_t *expires,
    time_t *expires_time, char **err)
{
    ngx_uint_t  minus;

    if (*expires != NGX_HTTP_EXPIRES_MODIFIED) {

        if (value->len == 5 && ngx_strncmp(value->data, "epoch", 5) == 0) {
            *expires = NGX_HTTP_EXPIRES_EPOCH;
            return NGX_OK;
        }

        if (value->len == 3 && ngx_strncmp(value->data, "max", 3) == 0) {
            *expires = NGX_HTTP_EXPIRES_MAX;
            return NGX_OK;
        }

        if (value->len == 3 && ngx_strncmp(value->data, "off", 3) == 0) {
            *expires = NGX_HTTP_EXPIRES_OFF;
            return NGX_OK;
        }
    }

    if (value->len && value->data[0] == '@') {
        value->data++;
        value->len--;
        minus = 0;

        if (*expires == NGX_HTTP_EXPIRES_MODIFIED) {
            *err = "daily time cannot be used with \"modified\" parameter";
            return NGX_ERROR;
        }

        *expires = NGX_HTTP_EXPIRES_DAILY;

    } else if (value->len && value->data[0] == '+') {
        value->data++;
        value->len--;
        minus = 0;

    } else if (value->len && value->data[0] == '-') {
        value->data++;
        value->len--;
        minus = 1;

    } else {
        minus = 0;
    }

    *expires_time = ngx_parse_time(value, 1);

    if (*expires_time == (time_t) NGX_ERROR) {
        *err = "invalid value";
        return NGX_ERROR;
    }

    if (*expires == NGX_HTTP_EXPIRES_DAILY
        && *expires_time > 24 * 60 * 60)
    {
        *err = "daily time value must be less than 24 hours";
        return NGX_ERROR;
    }

    if (minus) {
        *expires_time = - *expires_time;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_add_header(ngx_http_request_t *r, ngx_http_header_val_t *hv,
    ngx_str_t *value)
{
    ngx_table_elt_t  *h;

    if (value->len) {
        h = ngx_list_push(&r->headers_out.headers);
        if (h == NULL) {
            return NGX_ERROR;
        }

        h->hash = 1;
        h->key = hv->key;
        h->value = *value;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_add_multi_header_lines(ngx_http_request_t *r,
    ngx_http_header_val_t *hv, ngx_str_t *value)
{
    ngx_table_elt_t  *h, **ph;

    if (value->len == 0) {
        return NGX_OK;
    }

    h = ngx_list_push(&r->headers_out.headers);
    if (h == NULL) {
        return NGX_ERROR;
    }

    h->hash = 1;
    h->key = hv->key;
    h->value = *value;

    ph = (ngx_table_elt_t **) ((char *) &r->headers_out + hv->offset);

    while (*ph) { ph = &(*ph)->next; }

    *ph = h;
    h->next = NULL;

    return NGX_OK;
}


static ngx_int_t
ngx_http_set_last_modified(ngx_http_request_t *r, ngx_http_header_val_t *hv,
    ngx_str_t *value)
{
    if (ngx_http_set_response_header(r, hv, value) != NGX_OK) {
        return NGX_ERROR;
    }

    r->headers_out.last_modified_time =
        (value->len) ? ngx_parse_http_time(value->data, value->len) : -1;

    return NGX_OK;
}


static ngx_int_t
ngx_http_set_response_header(ngx_http_request_t *r, ngx_http_header_val_t *hv,
    ngx_str_t *value)
{
    ngx_table_elt_t  *h, **old;

    old = (ngx_table_elt_t **) ((char *) &r->headers_out + hv->offset);

    if (value->len == 0) {
        if (*old) {
            (*old)->hash = 0;
            *old = NULL;
        }

        return NGX_OK;
    }

    if (*old) {
        h = *old;

    } else {
        h = ngx_list_push(&r->headers_out.headers);
        if (h == NULL) {
            return NGX_ERROR;
        }

        *old = h;
        h->next = NULL;
    }

    h->hash = 1;
    h->key = hv->key;
    h->value = *value;

    return NGX_OK;
}


static void *
ngx_http_headers_create_conf(ngx_conf_t *cf)
{
    ngx_http_headers_conf_t  *conf;

    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_headers_conf_t));
    if (conf == NULL) {
        return NULL;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     conf->headers = NULL;
     *     conf->trailers = NULL;
     *     conf->expires_time = 0;
     *     conf->expires_value = NULL;
     */

    conf->expires = NGX_HTTP_EXPIRES_UNSET;

    return conf;
}


static char *
ngx_http_headers_merge_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_headers_conf_t *prev = parent;
    ngx_http_headers_conf_t *conf = child;

    if (conf->expires == NGX_HTTP_EXPIRES_UNSET) {
        conf->expires = prev->expires;
        conf->expires_time = prev->expires_time;
        conf->expires_value = prev->expires_value;

        if (conf->expires == NGX_HTTP_EXPIRES_UNSET) {
            conf->expires = NGX_HTTP_EXPIRES_OFF;
        }
    }

    if (conf->headers == NULL) {
        conf->headers = prev->headers;
    }

    if (conf->trailers == NULL) {
        conf->trailers = prev->trailers;
    }

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_headers_filter_init(ngx_conf_t *cf)
{
    ngx_http_next_header_filter = ngx_http_top_header_filter;
    ngx_http_top_header_filter = ngx_http_headers_filter;

    ngx_http_next_body_filter = ngx_http_top_body_filter;
    ngx_http_top_body_filter = ngx_http_trailers_filter;

    return NGX_OK;
}


static char *
ngx_http_headers_expires(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_headers_conf_t *hcf = conf;

    char                              *err;
    ngx_str_t                         *value;
    ngx_int_t                          rc;
    ngx_uint_t                         n;
    ngx_http_complex_value_t           cv;
    ngx_http_compile_complex_value_t   ccv;

    if (hcf->expires != NGX_HTTP_EXPIRES_UNSET) {
        return "is duplicate";
    }

    value = cf->args->elts;

    if (cf->args->nelts == 2) {

        hcf->expires = NGX_HTTP_EXPIRES_ACCESS;

        n = 1;

    } else { /* cf->args->nelts == 3 */

        if (ngx_strcmp(value[1].data, "modified") != 0) {
            return "invalid value";
        }

        hcf->expires = NGX_HTTP_EXPIRES_MODIFIED;

        n = 2;
    }

    ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));

    ccv.cf = cf;
    ccv.value = &value[n];
    ccv.complex_value = &cv;

    if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    if (cv.lengths != NULL) {

        hcf->expires_value = ngx_palloc(cf->pool,
                                        sizeof(ngx_http_complex_value_t));
        if (hcf->expires_value == NULL) {
            return NGX_CONF_ERROR;
        }

        *hcf->expires_value = cv;

        return NGX_CONF_OK;
    }

    rc = ngx_http_parse_expires(&value[n], &hcf->expires, &hcf->expires_time,
                                &err);
    if (rc != NGX_OK) {
        return err;
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_headers_add(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_headers_conf_t *hcf = conf;

    ngx_str_t                          *value;
    ngx_uint_t                          i;
    ngx_array_t                       **headers;
    ngx_http_header_val_t              *hv;
    ngx_http_set_header_t              *set;
    ngx_http_compile_complex_value_t    ccv;

    value = cf->args->elts;

    headers = (ngx_array_t **) ((char *) hcf + cmd->offset);

    if (*headers == NULL) {
        *headers = ngx_array_create(cf->pool, 1,
                                    sizeof(ngx_http_header_val_t));
        if (*headers == NULL) {
            return NGX_CONF_ERROR;
        }
    }

    hv = ngx_array_push(*headers);
    if (hv == NULL) {
        return NGX_CONF_ERROR;
    }

    hv->key = value[1];
    hv->handler = NULL;
    hv->offset = 0;
    hv->always = 0;

    if (headers == &hcf->headers) {
        hv->handler = ngx_http_add_header;

        set = ngx_http_set_headers;
        for (i = 0; set[i].name.len; i++) {
            if (ngx_strcasecmp(value[1].data, set[i].name.data) != 0) {
                continue;
            }

            hv->offset = set[i].offset;
            hv->handler = set[i].handler;

            break;
        }
    }

    if (value[2].len == 0) {
        ngx_memzero(&hv->value, sizeof(ngx_http_complex_value_t));

    } else {
        ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));

        ccv.cf = cf;
        ccv.value = &value[2];
        ccv.complex_value = &hv->value;

        if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    if (cf->args->nelts == 3) {
        return NGX_CONF_OK;
    }

    if (ngx_strcmp(value[3].data, "always") != 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid parameter \"%V\"", &value[3]);
        return NGX_CONF_ERROR;
    }

    hv->always = 1;

    return NGX_CONF_OK;
}