view src/stream/ngx_stream_limit_conn_module.c @ 6874:7cc2d3a96ea3

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 3908156a51fa
children 359b0ea2b067
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


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


typedef struct {
    u_char                       color;
    u_char                       len;
    u_short                      conn;
    u_char                       data[1];
} ngx_stream_limit_conn_node_t;


typedef struct {
    ngx_shm_zone_t              *shm_zone;
    ngx_rbtree_node_t           *node;
} ngx_stream_limit_conn_cleanup_t;


typedef struct {
    ngx_rbtree_t                *rbtree;
    ngx_stream_complex_value_t   key;
} ngx_stream_limit_conn_ctx_t;


typedef struct {
    ngx_shm_zone_t              *shm_zone;
    ngx_uint_t                   conn;
} ngx_stream_limit_conn_limit_t;


typedef struct {
    ngx_array_t                  limits;
    ngx_uint_t                   log_level;
} ngx_stream_limit_conn_conf_t;


static ngx_rbtree_node_t *ngx_stream_limit_conn_lookup(ngx_rbtree_t *rbtree,
    ngx_str_t *key, uint32_t hash);
static void ngx_stream_limit_conn_cleanup(void *data);
static ngx_inline void ngx_stream_limit_conn_cleanup_all(ngx_pool_t *pool);

static void *ngx_stream_limit_conn_create_conf(ngx_conf_t *cf);
static char *ngx_stream_limit_conn_merge_conf(ngx_conf_t *cf, void *parent,
    void *child);
static char *ngx_stream_limit_conn_zone(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_stream_limit_conn(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_stream_limit_conn_init(ngx_conf_t *cf);


static ngx_conf_enum_t  ngx_stream_limit_conn_log_levels[] = {
    { ngx_string("info"), NGX_LOG_INFO },
    { ngx_string("notice"), NGX_LOG_NOTICE },
    { ngx_string("warn"), NGX_LOG_WARN },
    { ngx_string("error"), NGX_LOG_ERR },
    { ngx_null_string, 0 }
};


static ngx_command_t  ngx_stream_limit_conn_commands[] = {

    { ngx_string("limit_conn_zone"),
      NGX_STREAM_MAIN_CONF|NGX_CONF_TAKE2,
      ngx_stream_limit_conn_zone,
      0,
      0,
      NULL },

    { ngx_string("limit_conn"),
      NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE2,
      ngx_stream_limit_conn,
      NGX_STREAM_SRV_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("limit_conn_log_level"),
      NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_STREAM_SRV_CONF_OFFSET,
      offsetof(ngx_stream_limit_conn_conf_t, log_level),
      &ngx_stream_limit_conn_log_levels },

      ngx_null_command
};


static ngx_stream_module_t  ngx_stream_limit_conn_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_stream_limit_conn_init,            /* postconfiguration */

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

    ngx_stream_limit_conn_create_conf,     /* create server configuration */
    ngx_stream_limit_conn_merge_conf       /* merge server configuration */
};


ngx_module_t  ngx_stream_limit_conn_module = {
    NGX_MODULE_V1,
    &ngx_stream_limit_conn_module_ctx,     /* module context */
    ngx_stream_limit_conn_commands,        /* module directives */
    NGX_STREAM_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_stream_limit_conn_handler(ngx_stream_session_t *s)
{
    size_t                            n;
    uint32_t                          hash;
    ngx_str_t                         key;
    ngx_uint_t                        i;
    ngx_slab_pool_t                  *shpool;
    ngx_rbtree_node_t                *node;
    ngx_pool_cleanup_t               *cln;
    ngx_stream_limit_conn_ctx_t      *ctx;
    ngx_stream_limit_conn_node_t     *lc;
    ngx_stream_limit_conn_conf_t     *lccf;
    ngx_stream_limit_conn_limit_t    *limits;
    ngx_stream_limit_conn_cleanup_t  *lccln;

    lccf = ngx_stream_get_module_srv_conf(s, ngx_stream_limit_conn_module);
    limits = lccf->limits.elts;

    for (i = 0; i < lccf->limits.nelts; i++) {
        ctx = limits[i].shm_zone->data;

        if (ngx_stream_complex_value(s, &ctx->key, &key) != NGX_OK) {
            return NGX_ERROR;
        }

        if (key.len == 0) {
            continue;
        }

        if (key.len > 255) {
            ngx_log_error(NGX_LOG_ERR, s->connection->log, 0,
                          "the value of the \"%V\" key "
                          "is more than 255 bytes: \"%V\"",
                          &ctx->key.value, &key);
            continue;
        }

        hash = ngx_crc32_short(key.data, key.len);

        shpool = (ngx_slab_pool_t *) limits[i].shm_zone->shm.addr;

        ngx_shmtx_lock(&shpool->mutex);

        node = ngx_stream_limit_conn_lookup(ctx->rbtree, &key, hash);

        if (node == NULL) {

            n = offsetof(ngx_rbtree_node_t, color)
                + offsetof(ngx_stream_limit_conn_node_t, data)
                + key.len;

            node = ngx_slab_alloc_locked(shpool, n);

            if (node == NULL) {
                ngx_shmtx_unlock(&shpool->mutex);
                ngx_stream_limit_conn_cleanup_all(s->connection->pool);
                return NGX_STREAM_SERVICE_UNAVAILABLE;
            }

            lc = (ngx_stream_limit_conn_node_t *) &node->color;

            node->key = hash;
            lc->len = (u_char) key.len;
            lc->conn = 1;
            ngx_memcpy(lc->data, key.data, key.len);

            ngx_rbtree_insert(ctx->rbtree, node);

        } else {

            lc = (ngx_stream_limit_conn_node_t *) &node->color;

            if ((ngx_uint_t) lc->conn >= limits[i].conn) {

                ngx_shmtx_unlock(&shpool->mutex);

                ngx_log_error(lccf->log_level, s->connection->log, 0,
                              "limiting connections by zone \"%V\"",
                              &limits[i].shm_zone->shm.name);

                ngx_stream_limit_conn_cleanup_all(s->connection->pool);
                return NGX_STREAM_SERVICE_UNAVAILABLE;
            }

            lc->conn++;
        }

        ngx_log_debug2(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
                       "limit conn: %08Xi %d", node->key, lc->conn);

        ngx_shmtx_unlock(&shpool->mutex);

        cln = ngx_pool_cleanup_add(s->connection->pool,
                                   sizeof(ngx_stream_limit_conn_cleanup_t));
        if (cln == NULL) {
            return NGX_ERROR;
        }

        cln->handler = ngx_stream_limit_conn_cleanup;
        lccln = cln->data;

        lccln->shm_zone = limits[i].shm_zone;
        lccln->node = node;
    }

    return NGX_DECLINED;
}


static void
ngx_stream_limit_conn_rbtree_insert_value(ngx_rbtree_node_t *temp,
    ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel)
{
    ngx_rbtree_node_t             **p;
    ngx_stream_limit_conn_node_t   *lcn, *lcnt;

    for ( ;; ) {

        if (node->key < temp->key) {

            p = &temp->left;

        } else if (node->key > temp->key) {

            p = &temp->right;

        } else { /* node->key == temp->key */

            lcn = (ngx_stream_limit_conn_node_t *) &node->color;
            lcnt = (ngx_stream_limit_conn_node_t *) &temp->color;

            p = (ngx_memn2cmp(lcn->data, lcnt->data, lcn->len, lcnt->len) < 0)
                ? &temp->left : &temp->right;
        }

        if (*p == sentinel) {
            break;
        }

        temp = *p;
    }

    *p = node;
    node->parent = temp;
    node->left = sentinel;
    node->right = sentinel;
    ngx_rbt_red(node);
}


static ngx_rbtree_node_t *
ngx_stream_limit_conn_lookup(ngx_rbtree_t *rbtree, ngx_str_t *key,
    uint32_t hash)
{
    ngx_int_t                      rc;
    ngx_rbtree_node_t             *node, *sentinel;
    ngx_stream_limit_conn_node_t  *lcn;

    node = rbtree->root;
    sentinel = rbtree->sentinel;

    while (node != sentinel) {

        if (hash < node->key) {
            node = node->left;
            continue;
        }

        if (hash > node->key) {
            node = node->right;
            continue;
        }

        /* hash == node->key */

        lcn = (ngx_stream_limit_conn_node_t *) &node->color;

        rc = ngx_memn2cmp(key->data, lcn->data, key->len, (size_t) lcn->len);

        if (rc == 0) {
            return node;
        }

        node = (rc < 0) ? node->left : node->right;
    }

    return NULL;
}


static void
ngx_stream_limit_conn_cleanup(void *data)
{
    ngx_stream_limit_conn_cleanup_t  *lccln = data;

    ngx_slab_pool_t               *shpool;
    ngx_rbtree_node_t             *node;
    ngx_stream_limit_conn_ctx_t   *ctx;
    ngx_stream_limit_conn_node_t  *lc;

    ctx = lccln->shm_zone->data;
    shpool = (ngx_slab_pool_t *) lccln->shm_zone->shm.addr;
    node = lccln->node;
    lc = (ngx_stream_limit_conn_node_t *) &node->color;

    ngx_shmtx_lock(&shpool->mutex);

    ngx_log_debug2(NGX_LOG_DEBUG_STREAM, lccln->shm_zone->shm.log, 0,
                   "limit conn cleanup: %08Xi %d", node->key, lc->conn);

    lc->conn--;

    if (lc->conn == 0) {
        ngx_rbtree_delete(ctx->rbtree, node);
        ngx_slab_free_locked(shpool, node);
    }

    ngx_shmtx_unlock(&shpool->mutex);
}


static ngx_inline void
ngx_stream_limit_conn_cleanup_all(ngx_pool_t *pool)
{
    ngx_pool_cleanup_t  *cln;

    cln = pool->cleanup;

    while (cln && cln->handler == ngx_stream_limit_conn_cleanup) {
        ngx_stream_limit_conn_cleanup(cln->data);
        cln = cln->next;
    }

    pool->cleanup = cln;
}


static ngx_int_t
ngx_stream_limit_conn_init_zone(ngx_shm_zone_t *shm_zone, void *data)
{
    ngx_stream_limit_conn_ctx_t  *octx = data;

    size_t                        len;
    ngx_slab_pool_t              *shpool;
    ngx_rbtree_node_t            *sentinel;
    ngx_stream_limit_conn_ctx_t  *ctx;

    ctx = shm_zone->data;

    if (octx) {
        if (ctx->key.value.len != octx->key.value.len
            || ngx_strncmp(ctx->key.value.data, octx->key.value.data,
                           ctx->key.value.len)
               != 0)
        {
            ngx_log_error(NGX_LOG_EMERG, shm_zone->shm.log, 0,
                          "limit_conn_zone \"%V\" uses the \"%V\" key "
                          "while previously it used the \"%V\" key",
                          &shm_zone->shm.name, &ctx->key.value,
                          &octx->key.value);
            return NGX_ERROR;
        }

        ctx->rbtree = octx->rbtree;

        return NGX_OK;
    }

    shpool = (ngx_slab_pool_t *) shm_zone->shm.addr;

    if (shm_zone->shm.exists) {
        ctx->rbtree = shpool->data;

        return NGX_OK;
    }

    ctx->rbtree = ngx_slab_alloc(shpool, sizeof(ngx_rbtree_t));
    if (ctx->rbtree == NULL) {
        return NGX_ERROR;
    }

    shpool->data = ctx->rbtree;

    sentinel = ngx_slab_alloc(shpool, sizeof(ngx_rbtree_node_t));
    if (sentinel == NULL) {
        return NGX_ERROR;
    }

    ngx_rbtree_init(ctx->rbtree, sentinel,
                    ngx_stream_limit_conn_rbtree_insert_value);

    len = sizeof(" in limit_conn_zone \"\"") + shm_zone->shm.name.len;

    shpool->log_ctx = ngx_slab_alloc(shpool, len);
    if (shpool->log_ctx == NULL) {
        return NGX_ERROR;
    }

    ngx_sprintf(shpool->log_ctx, " in limit_conn_zone \"%V\"%Z",
                &shm_zone->shm.name);

    return NGX_OK;
}


static void *
ngx_stream_limit_conn_create_conf(ngx_conf_t *cf)
{
    ngx_stream_limit_conn_conf_t  *conf;

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

    /*
     * set by ngx_pcalloc():
     *
     *     conf->limits.elts = NULL;
     */

    conf->log_level = NGX_CONF_UNSET_UINT;

    return conf;
}


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

    if (conf->limits.elts == NULL) {
        conf->limits = prev->limits;
    }

    ngx_conf_merge_uint_value(conf->log_level, prev->log_level, NGX_LOG_ERR);

    return NGX_CONF_OK;
}


static char *
ngx_stream_limit_conn_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    u_char                              *p;
    ssize_t                              size;
    ngx_str_t                           *value, name, s;
    ngx_uint_t                           i;
    ngx_shm_zone_t                      *shm_zone;
    ngx_stream_limit_conn_ctx_t         *ctx;
    ngx_stream_compile_complex_value_t   ccv;

    value = cf->args->elts;

    ctx = ngx_pcalloc(cf->pool, sizeof(ngx_stream_limit_conn_ctx_t));
    if (ctx == NULL) {
        return NGX_CONF_ERROR;
    }

    ngx_memzero(&ccv, sizeof(ngx_stream_compile_complex_value_t));

    ccv.cf = cf;
    ccv.value = &value[1];
    ccv.complex_value = &ctx->key;

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

    size = 0;
    name.len = 0;

    for (i = 2; i < cf->args->nelts; i++) {

        if (ngx_strncmp(value[i].data, "zone=", 5) == 0) {

            name.data = value[i].data + 5;

            p = (u_char *) ngx_strchr(name.data, ':');

            if (p == NULL) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid zone size \"%V\"", &value[i]);
                return NGX_CONF_ERROR;
            }

            name.len = p - name.data;

            s.data = p + 1;
            s.len = value[i].data + value[i].len - s.data;

            size = ngx_parse_size(&s);

            if (size == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid zone size \"%V\"", &value[i]);
                return NGX_CONF_ERROR;
            }

            if (size < (ssize_t) (8 * ngx_pagesize)) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "zone \"%V\" is too small", &value[i]);
                return NGX_CONF_ERROR;
            }

            continue;
        }

        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid parameter \"%V\"", &value[i]);
        return NGX_CONF_ERROR;
    }

    if (name.len == 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "\"%V\" must have \"zone\" parameter",
                           &cmd->name);
        return NGX_CONF_ERROR;
    }

    shm_zone = ngx_shared_memory_add(cf, &name, size,
                                     &ngx_stream_limit_conn_module);
    if (shm_zone == NULL) {
        return NGX_CONF_ERROR;
    }

    if (shm_zone->data) {
        ctx = shm_zone->data;

        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "%V \"%V\" is already bound to key \"%V\"",
                           &cmd->name, &name, &ctx->key.value);
        return NGX_CONF_ERROR;
    }

    shm_zone->init = ngx_stream_limit_conn_init_zone;
    shm_zone->data = ctx;

    return NGX_CONF_OK;
}


static char *
ngx_stream_limit_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_shm_zone_t                 *shm_zone;
    ngx_stream_limit_conn_conf_t   *lccf = conf;
    ngx_stream_limit_conn_limit_t  *limit, *limits;

    ngx_str_t   *value;
    ngx_int_t    n;
    ngx_uint_t   i;

    value = cf->args->elts;

    shm_zone = ngx_shared_memory_add(cf, &value[1], 0,
                                     &ngx_stream_limit_conn_module);
    if (shm_zone == NULL) {
        return NGX_CONF_ERROR;
    }

    limits = lccf->limits.elts;

    if (limits == NULL) {
        if (ngx_array_init(&lccf->limits, cf->pool, 1,
                           sizeof(ngx_stream_limit_conn_limit_t))
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }
    }

    for (i = 0; i < lccf->limits.nelts; i++) {
        if (shm_zone == limits[i].shm_zone) {
            return "is duplicate";
        }
    }

    n = ngx_atoi(value[2].data, value[2].len);
    if (n <= 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid number of connections \"%V\"", &value[2]);
        return NGX_CONF_ERROR;
    }

    if (n > 65535) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "connection limit must be less 65536");
        return NGX_CONF_ERROR;
    }

    limit = ngx_array_push(&lccf->limits);
    if (limit == NULL) {
        return NGX_CONF_ERROR;
    }

    limit->conn = n;
    limit->shm_zone = shm_zone;

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_stream_limit_conn_init(ngx_conf_t *cf)
{
    ngx_stream_handler_pt        *h;
    ngx_stream_core_main_conf_t  *cmcf;

    cmcf = ngx_stream_conf_get_module_main_conf(cf, ngx_stream_core_module);

    h = ngx_array_push(&cmcf->phases[NGX_STREAM_PREACCESS_PHASE].handlers);
    if (h == NULL) {
        return NGX_ERROR;
    }

    *h = ngx_stream_limit_conn_handler;

    return NGX_OK;
}