view src/stream/ngx_stream_split_clients_module.c @ 7098:7bfbf73db920

Stream: relaxed next upstream condition (ticket #1317). When switching to a next upstream, some buffers could be stuck in the middle of the filter chain. A condition existed that raised an error when this happened. As it turned out, this condition prevented switching to a next upstream if ssl preread was used with the TCP protocol (see the ticket). In fact, the condition does not make sense for TCP, since after successful connection to an upstream switching to another upstream never happens. As for UDP, the issue with stuck buffers is unlikely to happen, but is still possible. Specifically, if a filter delays sending data to upstream. The condition can be relaxed to only check the "buffered" bitmask of the upstream connection. The new condition is simpler and fixes the ticket issue as well. Additionally, the upstream_out chain is now reset for UDP prior to connecting to a new upstream to prevent repeating the client data twice.
author Roman Arutyunyan <arut@nginx.com>
date Mon, 11 Sep 2017 15:32:31 +0300
parents 787dcc15b802
children
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


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


typedef struct {
    uint32_t                      percent;
    ngx_stream_variable_value_t   value;
} ngx_stream_split_clients_part_t;


typedef struct {
    ngx_stream_complex_value_t    value;
    ngx_array_t                   parts;
} ngx_stream_split_clients_ctx_t;


static char *ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_stream_split_clients(ngx_conf_t *cf, ngx_command_t *dummy,
    void *conf);

static ngx_command_t  ngx_stream_split_clients_commands[] = {

    { ngx_string("split_clients"),
      NGX_STREAM_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE2,
      ngx_conf_split_clients_block,
      NGX_STREAM_MAIN_CONF_OFFSET,
      0,
      NULL },

      ngx_null_command
};


static ngx_stream_module_t  ngx_stream_split_clients_module_ctx = {
    NULL,                                  /* preconfiguration */
    NULL,                                  /* postconfiguration */

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

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


ngx_module_t  ngx_stream_split_clients_module = {
    NGX_MODULE_V1,
    &ngx_stream_split_clients_module_ctx,  /* module context */
    ngx_stream_split_clients_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_split_clients_variable(ngx_stream_session_t *s,
    ngx_stream_variable_value_t *v, uintptr_t data)
{
    ngx_stream_split_clients_ctx_t *ctx =
                                       (ngx_stream_split_clients_ctx_t *) data;

    uint32_t                          hash;
    ngx_str_t                         val;
    ngx_uint_t                        i;
    ngx_stream_split_clients_part_t  *part;

    *v = ngx_stream_variable_null_value;

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

    hash = ngx_murmur_hash2(val.data, val.len);

    part = ctx->parts.elts;

    for (i = 0; i < ctx->parts.nelts; i++) {

        ngx_log_debug2(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
                       "stream split: %uD %uD", hash, part[i].percent);

        if (hash < part[i].percent || part[i].percent == 0) {
            *v = part[i].value;
            return NGX_OK;
        }
    }

    return NGX_OK;
}


static char *
ngx_conf_split_clients_block(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    char                                *rv;
    uint32_t                             sum, last;
    ngx_str_t                           *value, name;
    ngx_uint_t                           i;
    ngx_conf_t                           save;
    ngx_stream_variable_t               *var;
    ngx_stream_split_clients_ctx_t      *ctx;
    ngx_stream_split_clients_part_t     *part;
    ngx_stream_compile_complex_value_t   ccv;

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

    value = cf->args->elts;

    ngx_memzero(&ccv, sizeof(ngx_stream_compile_complex_value_t));

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

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

    name = value[2];

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

    name.len--;
    name.data++;

    var = ngx_stream_add_variable(cf, &name, NGX_STREAM_VAR_CHANGEABLE);
    if (var == NULL) {
        return NGX_CONF_ERROR;
    }

    var->get_handler = ngx_stream_split_clients_variable;
    var->data = (uintptr_t) ctx;

    if (ngx_array_init(&ctx->parts, cf->pool, 2,
                       sizeof(ngx_stream_split_clients_part_t))
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    save = *cf;
    cf->ctx = ctx;
    cf->handler = ngx_stream_split_clients;
    cf->handler_conf = conf;

    rv = ngx_conf_parse(cf, NULL);

    *cf = save;

    if (rv != NGX_CONF_OK) {
        return rv;
    }

    sum = 0;
    last = 0;
    part = ctx->parts.elts;

    for (i = 0; i < ctx->parts.nelts; i++) {
        sum = part[i].percent ? sum + part[i].percent : 10000;
        if (sum > 10000) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "percent total is greater than 100%%");
            return NGX_CONF_ERROR;
        }

        if (part[i].percent) {
            last += part[i].percent * (uint64_t) 0xffffffff / 10000;
            part[i].percent = last;
        }
    }

    return rv;
}


static char *
ngx_stream_split_clients(ngx_conf_t *cf, ngx_command_t *dummy, void *conf)
{
    ngx_int_t                         n;
    ngx_str_t                        *value;
    ngx_stream_split_clients_ctx_t   *ctx;
    ngx_stream_split_clients_part_t  *part;

    ctx = cf->ctx;
    value = cf->args->elts;

    part = ngx_array_push(&ctx->parts);
    if (part == NULL) {
        return NGX_CONF_ERROR;
    }

    if (value[0].len == 1 && value[0].data[0] == '*') {
        part->percent = 0;

    } else {
        if (value[0].len == 0 || value[0].data[value[0].len - 1] != '%') {
            goto invalid;
        }

        n = ngx_atofp(value[0].data, value[0].len - 1, 2);
        if (n == NGX_ERROR || n == 0) {
            goto invalid;
        }

        part->percent = (uint32_t) n;
    }

    part->value.len = value[1].len;
    part->value.valid = 1;
    part->value.no_cacheable = 0;
    part->value.not_found = 0;
    part->value.data = value[1].data;

    return NGX_CONF_OK;

invalid:

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