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SSI: fixed incorrect or duplicate stub output. Following 3518:eb3aaf8bd2a9 (0.8.37), r->request_output is only set if there are data in the first buffer sent in the subrequest. As a result, following the change mentioned this flag cannot be used to prevent duplicate ngx_http_ssi_stub_output() calls, since it is not set if there was already some output, but the first buffer was empty. Still, when there are multiple subrequests, even an empty subrequest response might be delayed by the postpone filter, leading to a second call of ngx_http_ssi_stub_output() during finalization from ngx_http_writer() the subreqest buffers are released by the postpone filter. Since r->request_output is not set after the first call, this resulted in duplicate stub output. Additionally, checking only the first buffer might be wrong in some unusual cases. For example, the first buffer might be empty if $r->flush() is called before printing any data in the embedded Perl module. Depending on the postpone_output value and corresponding sizes, this issue can result in either duplicate or unexpected stub output, or "zero size buf in writer" alerts. Following 8124:f5515e727656 (1.23.4), it became slightly easier to reproduce the issue, as empty static files and empty cache items now result in a response with an empty buffer. Before the change, an empty proxied response can be used to reproduce the issue. Fix is check all buffers and set r->request_output if any non-empty buffers are sent. This ensures that all unusual cases of non-empty responses are covered, and also that r->request_output will be set after the first stub output, preventing duplicate output. Reported by Jan Gassen.
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 04 Jul 2024 17:41:28 +0300
parents ea1f29c2010c
children
line wrap: on
line source


/*
 * Copyright (C) Nginx, Inc.
 * Copyright (C) Valentin V. Bartenev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
#include <ngx_http_v2_module.h>


static ngx_int_t ngx_http_v2_add_variables(ngx_conf_t *cf);

static ngx_int_t ngx_http_v2_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);

static ngx_int_t ngx_http_v2_module_init(ngx_cycle_t *cycle);

static void *ngx_http_v2_create_main_conf(ngx_conf_t *cf);
static char *ngx_http_v2_init_main_conf(ngx_conf_t *cf, void *conf);
static void *ngx_http_v2_create_srv_conf(ngx_conf_t *cf);
static char *ngx_http_v2_merge_srv_conf(ngx_conf_t *cf, void *parent,
    void *child);
static void *ngx_http_v2_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_v2_merge_loc_conf(ngx_conf_t *cf, void *parent,
    void *child);

static char *ngx_http_v2_recv_buffer_size(ngx_conf_t *cf, void *post,
    void *data);
static char *ngx_http_v2_pool_size(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_v2_preread_size(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_v2_streams_index_mask(ngx_conf_t *cf, void *post,
    void *data);
static char *ngx_http_v2_chunk_size(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_v2_obsolete(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_conf_deprecated_t  ngx_http_v2_recv_timeout_deprecated = {
    ngx_conf_deprecated, "http2_recv_timeout", "client_header_timeout"
};

static ngx_conf_deprecated_t  ngx_http_v2_idle_timeout_deprecated = {
    ngx_conf_deprecated, "http2_idle_timeout", "keepalive_timeout"
};

static ngx_conf_deprecated_t  ngx_http_v2_max_requests_deprecated = {
    ngx_conf_deprecated, "http2_max_requests", "keepalive_requests"
};

static ngx_conf_deprecated_t  ngx_http_v2_max_field_size_deprecated = {
    ngx_conf_deprecated, "http2_max_field_size", "large_client_header_buffers"
};

static ngx_conf_deprecated_t  ngx_http_v2_max_header_size_deprecated = {
    ngx_conf_deprecated, "http2_max_header_size", "large_client_header_buffers"
};


static ngx_conf_post_t  ngx_http_v2_recv_buffer_size_post =
    { ngx_http_v2_recv_buffer_size };
static ngx_conf_post_t  ngx_http_v2_pool_size_post =
    { ngx_http_v2_pool_size };
static ngx_conf_post_t  ngx_http_v2_preread_size_post =
    { ngx_http_v2_preread_size };
static ngx_conf_post_t  ngx_http_v2_streams_index_mask_post =
    { ngx_http_v2_streams_index_mask };
static ngx_conf_post_t  ngx_http_v2_chunk_size_post =
    { ngx_http_v2_chunk_size };


static ngx_command_t  ngx_http_v2_commands[] = {

    { ngx_string("http2"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_v2_srv_conf_t, enable),
      NULL },

    { ngx_string("http2_recv_buffer_size"),
      NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_MAIN_CONF_OFFSET,
      offsetof(ngx_http_v2_main_conf_t, recv_buffer_size),
      &ngx_http_v2_recv_buffer_size_post },

    { ngx_string("http2_pool_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_v2_srv_conf_t, pool_size),
      &ngx_http_v2_pool_size_post },

    { ngx_string("http2_max_concurrent_streams"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_v2_srv_conf_t, concurrent_streams),
      NULL },

    { ngx_string("http2_max_concurrent_pushes"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      NULL },

    { ngx_string("http2_max_requests"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      &ngx_http_v2_max_requests_deprecated },

    { ngx_string("http2_max_field_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      &ngx_http_v2_max_field_size_deprecated },

    { ngx_string("http2_max_header_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      &ngx_http_v2_max_header_size_deprecated },

    { ngx_string("http2_body_preread_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_v2_srv_conf_t, preread_size),
      &ngx_http_v2_preread_size_post },

    { ngx_string("http2_streams_index_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_v2_srv_conf_t, streams_index_mask),
      &ngx_http_v2_streams_index_mask_post },

    { ngx_string("http2_recv_timeout"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      &ngx_http_v2_recv_timeout_deprecated },

    { ngx_string("http2_idle_timeout"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      &ngx_http_v2_idle_timeout_deprecated },

    { ngx_string("http2_chunk_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_v2_loc_conf_t, chunk_size),
      &ngx_http_v2_chunk_size_post },

    { ngx_string("http2_push_preload"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
      ngx_http_v2_obsolete,
      0,
      0,
      NULL },

    { ngx_string("http2_push"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_http_v2_obsolete,
      0,
      0,
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_v2_module_ctx = {
    ngx_http_v2_add_variables,             /* preconfiguration */
    NULL,                                  /* postconfiguration */

    ngx_http_v2_create_main_conf,          /* create main configuration */
    ngx_http_v2_init_main_conf,            /* init main configuration */

    ngx_http_v2_create_srv_conf,           /* create server configuration */
    ngx_http_v2_merge_srv_conf,            /* merge server configuration */

    ngx_http_v2_create_loc_conf,           /* create location configuration */
    ngx_http_v2_merge_loc_conf             /* merge location configuration */
};


ngx_module_t  ngx_http_v2_module = {
    NGX_MODULE_V1,
    &ngx_http_v2_module_ctx,               /* module context */
    ngx_http_v2_commands,                  /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    ngx_http_v2_module_init,               /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static ngx_http_variable_t  ngx_http_v2_vars[] = {

    { ngx_string("http2"), NULL,
      ngx_http_v2_variable, 0, 0, 0 },

      ngx_http_null_variable
};


static ngx_int_t
ngx_http_v2_add_variables(ngx_conf_t *cf)
{
    ngx_http_variable_t  *var, *v;

    for (v = ngx_http_v2_vars; v->name.len; v++) {
        var = ngx_http_add_variable(cf, &v->name, v->flags);
        if (var == NULL) {
            return NGX_ERROR;
        }

        var->get_handler = v->get_handler;
        var->data = v->data;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_v2_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{

    if (r->stream) {
#if (NGX_HTTP_SSL)

        if (r->connection->ssl) {
            v->len = sizeof("h2") - 1;
            v->valid = 1;
            v->no_cacheable = 0;
            v->not_found = 0;
            v->data = (u_char *) "h2";

            return NGX_OK;
        }

#endif
        v->len = sizeof("h2c") - 1;
        v->valid = 1;
        v->no_cacheable = 0;
        v->not_found = 0;
        v->data = (u_char *) "h2c";

        return NGX_OK;
    }

    *v = ngx_http_variable_null_value;

    return NGX_OK;
}


static ngx_int_t
ngx_http_v2_module_init(ngx_cycle_t *cycle)
{
    return NGX_OK;
}


static void *
ngx_http_v2_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_v2_main_conf_t  *h2mcf;

    h2mcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_v2_main_conf_t));
    if (h2mcf == NULL) {
        return NULL;
    }

    h2mcf->recv_buffer_size = NGX_CONF_UNSET_SIZE;

    return h2mcf;
}


static char *
ngx_http_v2_init_main_conf(ngx_conf_t *cf, void *conf)
{
    ngx_http_v2_main_conf_t *h2mcf = conf;

    ngx_conf_init_size_value(h2mcf->recv_buffer_size, 256 * 1024);

    return NGX_CONF_OK;
}


static void *
ngx_http_v2_create_srv_conf(ngx_conf_t *cf)
{
    ngx_http_v2_srv_conf_t  *h2scf;

    h2scf = ngx_pcalloc(cf->pool, sizeof(ngx_http_v2_srv_conf_t));
    if (h2scf == NULL) {
        return NULL;
    }

    h2scf->enable = NGX_CONF_UNSET;

    h2scf->pool_size = NGX_CONF_UNSET_SIZE;

    h2scf->concurrent_streams = NGX_CONF_UNSET_UINT;

    h2scf->preread_size = NGX_CONF_UNSET_SIZE;

    h2scf->streams_index_mask = NGX_CONF_UNSET_UINT;

    return h2scf;
}


static char *
ngx_http_v2_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_v2_srv_conf_t *prev = parent;
    ngx_http_v2_srv_conf_t *conf = child;

    ngx_conf_merge_value(conf->enable, prev->enable, 0);

    ngx_conf_merge_size_value(conf->pool_size, prev->pool_size, 4096);

    ngx_conf_merge_uint_value(conf->concurrent_streams,
                              prev->concurrent_streams, 128);

    ngx_conf_merge_size_value(conf->preread_size, prev->preread_size, 65536);

    ngx_conf_merge_uint_value(conf->streams_index_mask,
                              prev->streams_index_mask, 32 - 1);

    return NGX_CONF_OK;
}


static void *
ngx_http_v2_create_loc_conf(ngx_conf_t *cf)
{
    ngx_http_v2_loc_conf_t  *h2lcf;

    h2lcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_v2_loc_conf_t));
    if (h2lcf == NULL) {
        return NULL;
    }

    h2lcf->chunk_size = NGX_CONF_UNSET_SIZE;

    return h2lcf;
}


static char *
ngx_http_v2_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_v2_loc_conf_t *prev = parent;
    ngx_http_v2_loc_conf_t *conf = child;

    ngx_conf_merge_size_value(conf->chunk_size, prev->chunk_size, 8 * 1024);

    return NGX_CONF_OK;
}


static char *
ngx_http_v2_recv_buffer_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp <= NGX_HTTP_V2_STATE_BUFFER_SIZE) {
        return "value is too small";
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_v2_pool_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp < NGX_MIN_POOL_SIZE) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the pool size must be no less than %uz",
                           NGX_MIN_POOL_SIZE);

        return NGX_CONF_ERROR;
    }

    if (*sp % NGX_POOL_ALIGNMENT) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the pool size must be a multiple of %uz",
                           NGX_POOL_ALIGNMENT);

        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_v2_preread_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp > NGX_HTTP_V2_MAX_WINDOW) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the maximum body preread buffer size is %uz",
                           NGX_HTTP_V2_MAX_WINDOW);

        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_v2_streams_index_mask(ngx_conf_t *cf, void *post, void *data)
{
    ngx_uint_t *np = data;

    ngx_uint_t  mask;

    mask = *np - 1;

    if (*np == 0 || (*np & mask)) {
        return "must be a power of two";
    }

    *np = mask;

    return NGX_CONF_OK;
}


static char *
ngx_http_v2_chunk_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp == 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the http2 chunk size cannot be zero");

        return NGX_CONF_ERROR;
    }

    if (*sp > NGX_HTTP_V2_MAX_FRAME_SIZE) {
        *sp = NGX_HTTP_V2_MAX_FRAME_SIZE;
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_v2_obsolete(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_conf_deprecated_t  *d = cmd->post;

    if (d) {
        ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                           "the \"%s\" directive is obsolete, "
                           "use the \"%s\" directive instead",
                           d->old_name, d->new_name);

    } else {
        ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                           "the \"%V\" directive is obsolete, ignored",
                           &cmd->name);
    }

    return NGX_CONF_OK;
}