ngx_http_limit_speed_module.c

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


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


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


typedef struct {
    ngx_rbtree_t                 *rbtree;
    ngx_int_t                     index;
    ngx_str_t                     var;
} ngx_http_limit_speed_ctx_t;


typedef struct {
    ngx_shm_zone_t               *shm_zone;
    ngx_uint_t                    speed;
    ngx_uint_t                    var_max_len;
} ngx_http_limit_speed_conf_t;


typedef struct {
    ngx_uint_t                    speed;
    ngx_http_limit_speed_node_t  *ls;
} ngx_http_limit_speed_req_ctx_t;


static void ngx_http_limit_speed_cleanup(void *data);
static void *ngx_http_limit_speed_create_conf(ngx_conf_t *cf);
static char *ngx_http_limit_speed_merge_conf(ngx_conf_t *cf, void *parent,
    void *child);
static char *ngx_http_limit_speed_zone(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_http_limit_speed(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_http_limit_speed_init(ngx_conf_t *cf);
static ngx_int_t ngx_http_limit_speed_body_filter(ngx_http_request_t *r,
    ngx_chain_t *in);
static ngx_int_t ngx_http_limit_speed_add_ctx_variables(ngx_conf_t *cf);
static ngx_int_t ngx_http_limit_speed_ctx_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);


static ngx_command_t  ngx_http_limit_speed_commands[] = {

    { ngx_string("limit_speed_zone"),
      NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE3,
      ngx_http_limit_speed_zone,
      0,
      0,
      NULL },

    { ngx_string("limit_speed_zone_var_max_length"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_limit_speed_conf_t, var_max_len),
      NULL },

    { ngx_string("limit_speed"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE2,
      ngx_http_limit_speed,
      NGX_HTTP_LOC_CONF_OFFSET,
      0,
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_limit_speed_module_ctx = {
    ngx_http_limit_speed_add_ctx_variables, /* preconfiguration */
    ngx_http_limit_speed_init,              /* postconfiguration */

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

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

    ngx_http_limit_speed_create_conf,       /* create location configration */
    ngx_http_limit_speed_merge_conf         /* merge location configration */
};


ngx_module_t  ngx_http_limit_speed_module = {
    NGX_MODULE_V1,
    &ngx_http_limit_speed_module_ctx,       /* module context */
    ngx_http_limit_speed_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_str_t  ngx_http_limit_speed_ctx_var_name =
    ngx_string("__limit_speed_var__");
static ngx_int_t  ngx_http_limit_speed_ctx_var_index;
static ngx_http_output_body_filter_pt    ngx_http_next_body_filter;


static ngx_int_t
ngx_http_limit_speed_add_ctx_variables(ngx_conf_t *cf)
{
    ngx_http_variable_t  *var;

    var = ngx_http_add_variable(cf, &ngx_http_limit_speed_ctx_var_name,
                                NGX_HTTP_VAR_NOCACHEABLE);
    if (var == NULL) {
        return NGX_ERROR;
    }

    var->get_handler = ngx_http_limit_speed_ctx_variable;
    var->data = 0;

    return NGX_OK;
}


static ngx_int_t
ngx_http_limit_speed_ctx_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_http_limit_speed_req_ctx_t   *rctx;

    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "limit speed get ctx variable");

    rctx = ngx_http_get_module_ctx(r, ngx_http_limit_speed_module);
    if (rctx == NULL) {
        rctx = ngx_pcalloc(r->pool, sizeof(ngx_http_limit_speed_req_ctx_t));
        if (rctx == NULL) {
            return NGX_ERROR;
        }

        ngx_http_set_ctx(r, rctx, ngx_http_limit_speed_module);
    }

    v->data = (u_char *) rctx;
    v->len = sizeof(rctx);

    return NGX_OK;
}


ngx_int_t
ngx_http_limit_speed_get_ctx(ngx_http_request_t *r)
{
    ngx_http_variable_value_t        *vv;
    ngx_http_limit_speed_req_ctx_t   *rctx;

    rctx = ngx_http_get_module_ctx(r, ngx_http_limit_speed_module);

    if (rctx != NULL) {
        return NGX_OK;
    }

    vv = ngx_http_get_indexed_variable(r, ngx_http_limit_speed_ctx_var_index);

    if (vv == NULL || vv->not_found) {
        return NGX_ERROR;
    }

    rctx = (ngx_http_limit_speed_req_ctx_t *) vv->data;

    ngx_http_set_ctx(r, rctx, ngx_http_limit_speed_module);

    return NGX_OK;
}


static ngx_int_t
ngx_http_limit_speed_handler(ngx_http_request_t *r)
{
    size_t                           len, n;
    uint32_t                         hash;
    ngx_int_t                        rc;
    ngx_slab_pool_t                 *shpool;
    ngx_rbtree_node_t               *node, *sentinel;
    ngx_pool_cleanup_t              *cln;
    ngx_http_variable_value_t       *vv;
    ngx_http_limit_speed_ctx_t      *ctx;
    ngx_http_limit_speed_node_t     *ls;
    ngx_http_limit_speed_conf_t     *lscf;
    ngx_http_limit_speed_cleanup_t  *lscln;
    ngx_http_limit_speed_req_ctx_t  *rctx;

    if (r->main->limit_rate) {
        return NGX_DECLINED;
    }

    lscf = ngx_http_get_module_loc_conf(r, ngx_http_limit_speed_module);

    if (lscf->shm_zone == NULL) {
        return NGX_DECLINED;
    }

    ctx = lscf->shm_zone->data;

    vv = ngx_http_get_indexed_variable(r, ctx->index);

    if (vv == NULL || vv->not_found) {
        return NGX_DECLINED;
    }

    len = vv->len;

    if (len == 0) {
        return NGX_DECLINED;
    }

    if (lscf->var_max_len) {
        len = len > lscf->var_max_len ? lscf->var_max_len : len;
    }

    hash = ngx_crc32_short(vv->data, len);

    cln = ngx_pool_cleanup_add(r->pool, sizeof(ngx_http_limit_speed_cleanup_t));
    if (cln == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

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

    ngx_shmtx_lock(&shpool->mutex);

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

    while (node != sentinel) {

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

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

        /* hash == node->key */

        do {
            ls = (ngx_http_limit_speed_node_t *) &node->color;

            rc = ngx_memn2cmp(vv->data, ls->data, len, (size_t) ls->len);

            if (rc == 0) {
                ls->conn++;
                goto done;
            }

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

        } while (node != sentinel && hash == node->key);

        break;
    }

    n = offsetof(ngx_rbtree_node_t, color)
        + offsetof(ngx_http_limit_speed_node_t, data)
        + len;

    node = ngx_slab_alloc_locked(shpool, n);
    if (node == NULL) {
        ngx_shmtx_unlock(&shpool->mutex);
        return NGX_DECLINED;
    }

    ls = (ngx_http_limit_speed_node_t *) &node->color;

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

    ngx_rbtree_insert(ctx->rbtree, node);

done:

    r->main->limit_rate = lscf->speed / ls->conn;

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "limit speed zone: %08XD conn=%d, speed=%d",
                   node->key, ls->conn, r->main->limit_rate);

    ngx_shmtx_unlock(&shpool->mutex);

    cln->handler = ngx_http_limit_speed_cleanup;
    lscln = cln->data;

    lscln->shm_zone = lscf->shm_zone;
    lscln->node = node;

    if (ngx_http_limit_speed_get_ctx(r) != NGX_OK) {
        return NGX_DECLINED;
    }

    rctx = ngx_http_get_module_ctx(r, ngx_http_limit_speed_module);
    rctx->speed = lscf->speed;
    rctx->ls = ls;

    return NGX_DECLINED;
}


static void
ngx_http_limit_speed_rbtree_insert_value(ngx_rbtree_node_t *temp,
    ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel)
{
    ngx_rbtree_node_t            **p;
    ngx_http_limit_speed_node_t   *lsn, *lsnt;

    for ( ;; ) {

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

            p = &temp->left;

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

            p = &temp->right;

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

            lsn = (ngx_http_limit_speed_node_t *) &node->color;
            lsnt = (ngx_http_limit_speed_node_t *) &temp->color;

            p = (ngx_memn2cmp(lsn->data, lsnt->data, lsn->len, lsnt->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 void
ngx_http_limit_speed_cleanup(void *data)
{
    ngx_http_limit_speed_cleanup_t  *lscln = data;

    ngx_slab_pool_t                 *shpool;
    ngx_rbtree_node_t               *node;
    ngx_http_limit_speed_ctx_t      *ctx;
    ngx_http_limit_speed_node_t     *ls;

    ctx = lscln->shm_zone->data;
    shpool = (ngx_slab_pool_t *) lscln->shm_zone->shm.addr;
    node = lscln->node;
    ls = (ngx_http_limit_speed_node_t *) &node->color;

    ngx_shmtx_lock(&shpool->mutex);

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, lscln->shm_zone->shm.log, 0,
                   "limit speed cleanup: %08XD %d", node->key, ls->conn);

    ls->conn--;

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

    ngx_shmtx_unlock(&shpool->mutex);
}


static ngx_int_t
ngx_http_limit_speed_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    ngx_http_limit_speed_req_ctx_t  *rctx;

    if (ngx_http_limit_speed_get_ctx(r) != NGX_OK) {
        goto done;
    }

    rctx = ngx_http_get_module_ctx(r, ngx_http_limit_speed_module);

    ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
                  "limit speed rate: %ui rctx: %p %p", r->main->limit_rate,
                  rctx, r);

    if (rctx == NULL || rctx->ls == NULL || rctx->ls->conn == 0) {
        goto done;
    }

    r->main->limit_rate = rctx->speed / rctx->ls->conn;

done:
    return ngx_http_next_body_filter(r, in);
}


static ngx_int_t
ngx_http_limit_speed_init_zone(ngx_shm_zone_t *shm_zone, void *data)
{
    ngx_http_limit_speed_ctx_t  *octx = data;

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

    ctx = shm_zone->data;

    if (octx) {
        if (ngx_strcmp(ctx->var.data, octx->var.data) != 0) {
            ngx_log_error(NGX_LOG_EMERG, shm_zone->shm.log, 0,
                          "limit_speed \"%V\" uses the \"%V\" variable "
                          "while previously it used the \"%V\" variable",
                          &shm_zone->shm.name, &ctx->var, &octx->var);
            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_http_limit_speed_rbtree_insert_value);

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

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

    ngx_http_next_body_filter = ngx_http_top_body_filter;
    ngx_http_top_body_filter = ngx_http_limit_speed_body_filter;

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

    return NGX_OK;
}


static void *
ngx_http_limit_speed_create_conf(ngx_conf_t *cf)
{
    ngx_http_limit_speed_conf_t  *conf;

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

    conf->var_max_len = NGX_CONF_UNSET_UINT;

    /*
     * set by ngx_pcalloc():
     *
     *     conf->shm_zone = NULL;
     *     conf->conn = 0;
     */

    return conf;
}


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

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

    ngx_conf_merge_uint_value(conf->var_max_len, prev->var_max_len, 0);

    return NGX_CONF_OK;
}


static char *
ngx_http_limit_speed_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ssize_t                      n;
    ngx_str_t                   *value;
    ngx_shm_zone_t              *shm_zone;
    ngx_http_limit_speed_ctx_t  *ctx;

    value = cf->args->elts;

    if (value[2].data[0] != '$') {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid variable name \"%V\"", &value[2]);
        return NGX_CONF_ERROR;
    }

    value[2].len--;
    value[2].data++;

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

    ctx->index = ngx_http_get_variable_index(cf, &value[2]);
    if (ctx->index == NGX_ERROR) {
        return NGX_CONF_ERROR;
    }

    ctx->var = value[2];

    n = ngx_parse_size(&value[3]);

    if (n == NGX_ERROR) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid size of limit_speed_zone \"%V\"", &value[3]);
        return NGX_CONF_ERROR;
    }

    if (n < (ngx_int_t) (8 * ngx_pagesize)) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "limit_speed_zone \"%V\" is too small", &value[1]);
        return NGX_CONF_ERROR;
    }

    shm_zone = ngx_shared_memory_add(cf, &value[1], n,
                                     &ngx_http_limit_speed_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,
                        "limit_speed_zone \"%V\" is already bound to variable \"%V\"",
                        &value[1], &ctx->var);
        return NGX_CONF_ERROR;
    }

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

    return NGX_CONF_OK;
}


static char *
ngx_http_limit_speed(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_limit_speed_conf_t  *lscf = conf;

    ngx_int_t   n;
    ngx_str_t  *value;

    if (lscf->shm_zone) {
        return "is duplicate";
    }

    value = cf->args->elts;

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

    n = ngx_parse_size(&value[2]);
    if (n <= 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid limit speed of connections \"%V\"",
                           &value[2]);
        return NGX_CONF_ERROR;
    }

    lscf->speed = n;

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_limit_speed_init(ngx_conf_t *cf)
{
    ngx_http_handler_pt        *h;
    ngx_http_core_main_conf_t  *cmcf;

    cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);

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

    *h = ngx_http_limit_speed_handler;

    ngx_http_limit_speed_ctx_var_index =
        ngx_http_get_variable_index(cf, &ngx_http_limit_speed_ctx_var_name);

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

    return NGX_OK;
}