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view src/http/modules/ngx_http_referer_module.c @ 6874:7cc2d3a96ea3

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Fixed trailer construction with limit on FreeBSD and macOS. The ngx_chain_coalesce_file() function may produce more bytes to send then requested in the limit passed, as it aligns the last file position to send to memory page boundary. As a result, (limit - send) may become negative. This resulted in big positive number when converted to size_t while calling ngx_output_chain_to_iovec(). Another part of the problem is in ngx_chain_coalesce_file(): it changes cl to the next chain link even if the current buffer is only partially sent due to limit. Therefore, if a file buffer was not expected to be fully sent due to limit, and was followed by a memory buffer, nginx called sendfile() with a part of the file buffer, and the memory buffer in trailer. If there were enough room in the socket buffer, this resulted in a part of the file buffer being skipped, and corresponding part of the memory buffer sent instead. The bug was introduced in 8e903522c17a (1.7.8). Configurations affected are ones using limits, that is, limit_rate and/or sendfile_max_chunk, and memory buffers after file ones (may happen when using subrequests or with proxying with disk buffering). Fix is to explicitly check if (send < limit) before constructing trailer with ngx_output_chain_to_iovec(). Additionally, ngx_chain_coalesce_file() was modified to preserve unfinished file buffers in cl.
author Maxim Dounin <mdounin@mdounin.ru>
date Fri, 20 Jan 2017 21:12:48 +0300
parents 2cd019520210
children 7564a919d333
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>


#define NGX_HTTP_REFERER_NO_URI_PART  ((void *) 4)


typedef struct {
    ngx_hash_combined_t      hash;

#if (NGX_PCRE)
    ngx_array_t             *regex;
    ngx_array_t             *server_name_regex;
#endif

    ngx_flag_t               no_referer;
    ngx_flag_t               blocked_referer;
    ngx_flag_t               server_names;

    ngx_hash_keys_arrays_t  *keys;

    ngx_uint_t               referer_hash_max_size;
    ngx_uint_t               referer_hash_bucket_size;
} ngx_http_referer_conf_t;


static void * ngx_http_referer_create_conf(ngx_conf_t *cf);
static char * ngx_http_referer_merge_conf(ngx_conf_t *cf, void *parent,
    void *child);
static char *ngx_http_valid_referers(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_http_add_referer(ngx_conf_t *cf,
    ngx_hash_keys_arrays_t *keys, ngx_str_t *value, ngx_str_t *uri);
static ngx_int_t ngx_http_add_regex_referer(ngx_conf_t *cf,
    ngx_http_referer_conf_t *rlcf, ngx_str_t *name);
#if (NGX_PCRE)
static ngx_int_t ngx_http_add_regex_server_name(ngx_conf_t *cf,
    ngx_http_referer_conf_t *rlcf, ngx_http_regex_t *regex);
#endif
static int ngx_libc_cdecl ngx_http_cmp_referer_wildcards(const void *one,
    const void *two);


static ngx_command_t  ngx_http_referer_commands[] = {

    { ngx_string("valid_referers"),
      NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
      ngx_http_valid_referers,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("referer_hash_max_size"),
      NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_referer_conf_t, referer_hash_max_size),
      NULL },

    { ngx_string("referer_hash_bucket_size"),
      NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_referer_conf_t, referer_hash_bucket_size),
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_referer_module_ctx = {
    NULL,                                  /* preconfiguration */
    NULL,                                  /* postconfiguration */

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

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

    ngx_http_referer_create_conf,          /* create location configuration */
    ngx_http_referer_merge_conf            /* merge location configuration */
};


ngx_module_t  ngx_http_referer_module = {
    NGX_MODULE_V1,
    &ngx_http_referer_module_ctx,          /* module context */
    ngx_http_referer_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_int_t
ngx_http_referer_variable(ngx_http_request_t *r, ngx_http_variable_value_t *v,
    uintptr_t data)
{
    u_char                    *p, *ref, *last;
    size_t                     len;
    ngx_str_t                 *uri;
    ngx_uint_t                 i, key;
    ngx_http_referer_conf_t   *rlcf;
    u_char                     buf[256];
#if (NGX_PCRE)
    ngx_int_t                  rc;
    ngx_str_t                  referer;
#endif

    rlcf = ngx_http_get_module_loc_conf(r, ngx_http_referer_module);

    if (rlcf->hash.hash.buckets == NULL
        && rlcf->hash.wc_head == NULL
        && rlcf->hash.wc_tail == NULL
#if (NGX_PCRE)
        && rlcf->regex == NULL
        && rlcf->server_name_regex == NULL
#endif
       )
    {
        goto valid;
    }

    if (r->headers_in.referer == NULL) {
        if (rlcf->no_referer) {
            goto valid;
        }

        goto invalid;
    }

    len = r->headers_in.referer->value.len;
    ref = r->headers_in.referer->value.data;

    if (len >= sizeof("http://i.ru") - 1) {
        last = ref + len;

        if (ngx_strncasecmp(ref, (u_char *) "http://", 7) == 0) {
            ref += 7;
            len -= 7;
            goto valid_scheme;

        } else if (ngx_strncasecmp(ref, (u_char *) "https://", 8) == 0) {
            ref += 8;
            len -= 8;
            goto valid_scheme;
        }
    }

    if (rlcf->blocked_referer) {
        goto valid;
    }

    goto invalid;

valid_scheme:

    i = 0;
    key = 0;

    for (p = ref; p < last; p++) {
        if (*p == '/' || *p == ':') {
            break;
        }

        if (i == 256) {
            goto invalid;
        }

        buf[i] = ngx_tolower(*p);
        key = ngx_hash(key, buf[i++]);
    }

    uri = ngx_hash_find_combined(&rlcf->hash, key, buf, p - ref);

    if (uri) {
        goto uri;
    }

#if (NGX_PCRE)

    if (rlcf->server_name_regex) {
        referer.len = p - ref;
        referer.data = buf;

        rc = ngx_regex_exec_array(rlcf->server_name_regex, &referer,
                                  r->connection->log);

        if (rc == NGX_OK) {
            goto valid;
        }

        if (rc == NGX_ERROR) {
            return rc;
        }

        /* NGX_DECLINED */
    }

    if (rlcf->regex) {
        referer.len = len;
        referer.data = ref;

        rc = ngx_regex_exec_array(rlcf->regex, &referer, r->connection->log);

        if (rc == NGX_OK) {
            goto valid;
        }

        if (rc == NGX_ERROR) {
            return rc;
        }

        /* NGX_DECLINED */
    }

#endif

invalid:

    *v = ngx_http_variable_true_value;

    return NGX_OK;

uri:

    for ( /* void */ ; p < last; p++) {
        if (*p == '/') {
            break;
        }
    }

    len = last - p;

    if (uri == NGX_HTTP_REFERER_NO_URI_PART) {
        goto valid;
    }

    if (len < uri->len || ngx_strncmp(uri->data, p, uri->len) != 0) {
        goto invalid;
    }

valid:

    *v = ngx_http_variable_null_value;

    return NGX_OK;
}


static void *
ngx_http_referer_create_conf(ngx_conf_t *cf)
{
    ngx_http_referer_conf_t  *conf;

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

    /*
     * set by ngx_pcalloc():
     *
     *     conf->hash = { NULL };
     *     conf->server_names = 0;
     *     conf->keys = NULL;
     */

#if (NGX_PCRE)
    conf->regex = NGX_CONF_UNSET_PTR;
    conf->server_name_regex = NGX_CONF_UNSET_PTR;
#endif

    conf->no_referer = NGX_CONF_UNSET;
    conf->blocked_referer = NGX_CONF_UNSET;
    conf->referer_hash_max_size = NGX_CONF_UNSET_UINT;
    conf->referer_hash_bucket_size = NGX_CONF_UNSET_UINT;

    return conf;
}


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

    ngx_uint_t                 n;
    ngx_hash_init_t            hash;
    ngx_http_server_name_t    *sn;
    ngx_http_core_srv_conf_t  *cscf;

    if (conf->keys == NULL) {
        conf->hash = prev->hash;

#if (NGX_PCRE)
        ngx_conf_merge_ptr_value(conf->regex, prev->regex, NULL);
        ngx_conf_merge_ptr_value(conf->server_name_regex,
                                 prev->server_name_regex, NULL);
#endif
        ngx_conf_merge_value(conf->no_referer, prev->no_referer, 0);
        ngx_conf_merge_value(conf->blocked_referer, prev->blocked_referer, 0);
        ngx_conf_merge_uint_value(conf->referer_hash_max_size,
                                  prev->referer_hash_max_size, 2048);
        ngx_conf_merge_uint_value(conf->referer_hash_bucket_size,
                                  prev->referer_hash_bucket_size, 64);

        return NGX_CONF_OK;
    }

    if (conf->server_names == 1) {
        cscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_core_module);

        sn = cscf->server_names.elts;
        for (n = 0; n < cscf->server_names.nelts; n++) {

#if (NGX_PCRE)
            if (sn[n].regex) {

                if (ngx_http_add_regex_server_name(cf, conf, sn[n].regex)
                    != NGX_OK)
                {
                    return NGX_CONF_ERROR;
                }

                continue;
            }
#endif

            if (ngx_http_add_referer(cf, conf->keys, &sn[n].name, NULL)
                != NGX_OK)
            {
                return NGX_CONF_ERROR;
            }
        }
    }

    if ((conf->no_referer == 1 || conf->blocked_referer == 1)
        && conf->keys->keys.nelts == 0
        && conf->keys->dns_wc_head.nelts == 0
        && conf->keys->dns_wc_tail.nelts == 0)
    {
        ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                      "the \"none\" or \"blocked\" referers are specified "
                      "in the \"valid_referers\" directive "
                      "without any valid referer");
        return NGX_CONF_ERROR;
    }

    ngx_conf_merge_uint_value(conf->referer_hash_max_size,
                              prev->referer_hash_max_size, 2048);
    ngx_conf_merge_uint_value(conf->referer_hash_bucket_size,
                              prev->referer_hash_bucket_size, 64);
    conf->referer_hash_bucket_size = ngx_align(conf->referer_hash_bucket_size,
                                               ngx_cacheline_size);

    hash.key = ngx_hash_key_lc;
    hash.max_size = conf->referer_hash_max_size;
    hash.bucket_size = conf->referer_hash_bucket_size;
    hash.name = "referer_hash";
    hash.pool = cf->pool;

    if (conf->keys->keys.nelts) {
        hash.hash = &conf->hash.hash;
        hash.temp_pool = NULL;

        if (ngx_hash_init(&hash, conf->keys->keys.elts, conf->keys->keys.nelts)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }
    }

    if (conf->keys->dns_wc_head.nelts) {

        ngx_qsort(conf->keys->dns_wc_head.elts,
                  (size_t) conf->keys->dns_wc_head.nelts,
                  sizeof(ngx_hash_key_t),
                  ngx_http_cmp_referer_wildcards);

        hash.hash = NULL;
        hash.temp_pool = cf->temp_pool;

        if (ngx_hash_wildcard_init(&hash, conf->keys->dns_wc_head.elts,
                                   conf->keys->dns_wc_head.nelts)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }

        conf->hash.wc_head = (ngx_hash_wildcard_t *) hash.hash;
    }

    if (conf->keys->dns_wc_tail.nelts) {

        ngx_qsort(conf->keys->dns_wc_tail.elts,
                  (size_t) conf->keys->dns_wc_tail.nelts,
                  sizeof(ngx_hash_key_t),
                  ngx_http_cmp_referer_wildcards);

        hash.hash = NULL;
        hash.temp_pool = cf->temp_pool;

        if (ngx_hash_wildcard_init(&hash, conf->keys->dns_wc_tail.elts,
                                   conf->keys->dns_wc_tail.nelts)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }

        conf->hash.wc_tail = (ngx_hash_wildcard_t *) hash.hash;
    }

#if (NGX_PCRE)
    ngx_conf_merge_ptr_value(conf->regex, prev->regex, NULL);
    ngx_conf_merge_ptr_value(conf->server_name_regex, prev->server_name_regex,
                             NULL);
#endif

    if (conf->no_referer == NGX_CONF_UNSET) {
        conf->no_referer = 0;
    }

    if (conf->blocked_referer == NGX_CONF_UNSET) {
        conf->blocked_referer = 0;
    }

    conf->keys = NULL;

    return NGX_CONF_OK;
}


static char *
ngx_http_valid_referers(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_referer_conf_t  *rlcf = conf;

    u_char                    *p;
    ngx_str_t                 *value, uri, name;
    ngx_uint_t                 i;
    ngx_http_variable_t       *var;

    ngx_str_set(&name, "invalid_referer");

    var = ngx_http_add_variable(cf, &name, NGX_HTTP_VAR_CHANGEABLE);
    if (var == NULL) {
        return NGX_CONF_ERROR;
    }

    var->get_handler = ngx_http_referer_variable;

    if (rlcf->keys == NULL) {
        rlcf->keys = ngx_pcalloc(cf->temp_pool, sizeof(ngx_hash_keys_arrays_t));
        if (rlcf->keys == NULL) {
            return NGX_CONF_ERROR;
        }

        rlcf->keys->pool = cf->pool;
        rlcf->keys->temp_pool = cf->pool;

        if (ngx_hash_keys_array_init(rlcf->keys, NGX_HASH_SMALL) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    value = cf->args->elts;

    for (i = 1; i < cf->args->nelts; i++) {
        if (value[i].len == 0) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid referer \"%V\"", &value[i]);
            return NGX_CONF_ERROR;
        }

        if (ngx_strcmp(value[i].data, "none") == 0) {
            rlcf->no_referer = 1;
            continue;
        }

        if (ngx_strcmp(value[i].data, "blocked") == 0) {
            rlcf->blocked_referer = 1;
            continue;
        }

        if (ngx_strcmp(value[i].data, "server_names") == 0) {
            rlcf->server_names = 1;
            continue;
        }

        if (value[i].data[0] == '~') {
            if (ngx_http_add_regex_referer(cf, rlcf, &value[i]) != NGX_OK) {
                return NGX_CONF_ERROR;
            }

            continue;
        }

        ngx_str_null(&uri);

        p = (u_char *) ngx_strchr(value[i].data, '/');

        if (p) {
            uri.len = (value[i].data + value[i].len) - p;
            uri.data = p;
            value[i].len = p - value[i].data;
        }

        if (ngx_http_add_referer(cf, rlcf->keys, &value[i], &uri) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_add_referer(ngx_conf_t *cf, ngx_hash_keys_arrays_t *keys,
    ngx_str_t *value, ngx_str_t *uri)
{
    ngx_int_t   rc;
    ngx_str_t  *u;

    if (uri == NULL || uri->len == 0) {
        u = NGX_HTTP_REFERER_NO_URI_PART;

    } else {
        u = ngx_palloc(cf->pool, sizeof(ngx_str_t));
        if (u == NULL) {
            return NGX_ERROR;
        }

        *u = *uri;
    }

    rc = ngx_hash_add_key(keys, value, u, NGX_HASH_WILDCARD_KEY);

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

    if (rc == NGX_DECLINED) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid hostname or wildcard \"%V\"", value);
    }

    if (rc == NGX_BUSY) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "conflicting parameter \"%V\"", value);
    }

    return NGX_ERROR;
}


static ngx_int_t
ngx_http_add_regex_referer(ngx_conf_t *cf, ngx_http_referer_conf_t *rlcf,
    ngx_str_t *name)
{
#if (NGX_PCRE)
    ngx_regex_elt_t      *re;
    ngx_regex_compile_t   rc;
    u_char                errstr[NGX_MAX_CONF_ERRSTR];

    if (name->len == 1) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "empty regex in \"%V\"", name);
        return NGX_ERROR;
    }

    if (rlcf->regex == NGX_CONF_UNSET_PTR) {
        rlcf->regex = ngx_array_create(cf->pool, 2, sizeof(ngx_regex_elt_t));
        if (rlcf->regex == NULL) {
            return NGX_ERROR;
        }
    }

    re = ngx_array_push(rlcf->regex);
    if (re == NULL) {
        return NGX_ERROR;
    }

    name->len--;
    name->data++;

    ngx_memzero(&rc, sizeof(ngx_regex_compile_t));

    rc.pattern = *name;
    rc.pool = cf->pool;
    rc.options = NGX_REGEX_CASELESS;
    rc.err.len = NGX_MAX_CONF_ERRSTR;
    rc.err.data = errstr;

    if (ngx_regex_compile(&rc) != NGX_OK) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "%V", &rc.err);
        return NGX_ERROR;
    }

    re->regex = rc.regex;
    re->name = name->data;

    return NGX_OK;

#else

    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "the using of the regex \"%V\" requires PCRE library",
                       name);

    return NGX_ERROR;

#endif
}


#if (NGX_PCRE)

static ngx_int_t
ngx_http_add_regex_server_name(ngx_conf_t *cf, ngx_http_referer_conf_t *rlcf,
    ngx_http_regex_t *regex)
{
    ngx_regex_elt_t  *re;

    if (rlcf->server_name_regex == NGX_CONF_UNSET_PTR) {
        rlcf->server_name_regex = ngx_array_create(cf->pool, 2,
                                                   sizeof(ngx_regex_elt_t));
        if (rlcf->server_name_regex == NULL) {
            return NGX_ERROR;
        }
    }

    re = ngx_array_push(rlcf->server_name_regex);
    if (re == NULL) {
        return NGX_ERROR;
    }

    re->regex = regex->regex;
    re->name = regex->name.data;

    return NGX_OK;
}

#endif


static int ngx_libc_cdecl
ngx_http_cmp_referer_wildcards(const void *one, const void *two)
{
    ngx_hash_key_t  *first, *second;

    first = (ngx_hash_key_t *) one;
    second = (ngx_hash_key_t *) two;

    return ngx_dns_strcmp(first->key.data, second->key.data);
}