view src/stream/ngx_stream_upstream_zone_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 ac120e797d28
children 3b1b81e248bc
line wrap: on
line source


/*
 * Copyright (C) Ruslan Ermilov
 * Copyright (C) Nginx, Inc.
 */


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


static char *ngx_stream_upstream_zone(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_stream_upstream_init_zone(ngx_shm_zone_t *shm_zone,
    void *data);
static ngx_stream_upstream_rr_peers_t *ngx_stream_upstream_zone_copy_peers(
    ngx_slab_pool_t *shpool, ngx_stream_upstream_srv_conf_t *uscf);
static ngx_stream_upstream_rr_peer_t *ngx_stream_upstream_zone_copy_peer(
    ngx_stream_upstream_rr_peers_t *peers, ngx_stream_upstream_rr_peer_t *src);


static ngx_command_t  ngx_stream_upstream_zone_commands[] = {

    { ngx_string("zone"),
      NGX_STREAM_UPS_CONF|NGX_CONF_TAKE12,
      ngx_stream_upstream_zone,
      0,
      0,
      NULL },

      ngx_null_command
};


static ngx_stream_module_t  ngx_stream_upstream_zone_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_upstream_zone_module = {
    NGX_MODULE_V1,
    &ngx_stream_upstream_zone_module_ctx,  /* module context */
    ngx_stream_upstream_zone_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 char *
ngx_stream_upstream_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ssize_t                           size;
    ngx_str_t                        *value;
    ngx_stream_upstream_srv_conf_t   *uscf;
    ngx_stream_upstream_main_conf_t  *umcf;

    uscf = ngx_stream_conf_get_module_srv_conf(cf, ngx_stream_upstream_module);
    umcf = ngx_stream_conf_get_module_main_conf(cf, ngx_stream_upstream_module);

    value = cf->args->elts;

    if (!value[1].len) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid zone name \"%V\"", &value[1]);
        return NGX_CONF_ERROR;
    }

    if (cf->args->nelts == 3) {
        size = ngx_parse_size(&value[2]);

        if (size == NGX_ERROR) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid zone size \"%V\"", &value[2]);
            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[1]);
            return NGX_CONF_ERROR;
        }

    } else {
        size = 0;
    }

    uscf->shm_zone = ngx_shared_memory_add(cf, &value[1], size,
                                           &ngx_stream_upstream_module);
    if (uscf->shm_zone == NULL) {
        return NGX_CONF_ERROR;
    }

    uscf->shm_zone->init = ngx_stream_upstream_init_zone;
    uscf->shm_zone->data = umcf;

    uscf->shm_zone->noreuse = 1;

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_stream_upstream_init_zone(ngx_shm_zone_t *shm_zone, void *data)
{
    size_t                            len;
    ngx_uint_t                        i;
    ngx_slab_pool_t                  *shpool;
    ngx_stream_upstream_rr_peers_t   *peers, **peersp;
    ngx_stream_upstream_srv_conf_t   *uscf, **uscfp;
    ngx_stream_upstream_main_conf_t  *umcf;

    shpool = (ngx_slab_pool_t *) shm_zone->shm.addr;
    umcf = shm_zone->data;
    uscfp = umcf->upstreams.elts;

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

        for (i = 0; i < umcf->upstreams.nelts; i++) {
            uscf = uscfp[i];

            if (uscf->shm_zone != shm_zone) {
                continue;
            }

            uscf->peer.data = peers;
            peers = peers->zone_next;
        }

        return NGX_OK;
    }

    len = sizeof(" in upstream 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 upstream zone \"%V\"%Z",
                &shm_zone->shm.name);


    /* copy peers to shared memory */

    peersp = (ngx_stream_upstream_rr_peers_t **) (void *) &shpool->data;

    for (i = 0; i < umcf->upstreams.nelts; i++) {
        uscf = uscfp[i];

        if (uscf->shm_zone != shm_zone) {
            continue;
        }

        peers = ngx_stream_upstream_zone_copy_peers(shpool, uscf);
        if (peers == NULL) {
            return NGX_ERROR;
        }

        *peersp = peers;
        peersp = &peers->zone_next;
    }

    return NGX_OK;
}


static ngx_stream_upstream_rr_peers_t *
ngx_stream_upstream_zone_copy_peers(ngx_slab_pool_t *shpool,
    ngx_stream_upstream_srv_conf_t *uscf)
{
    ngx_str_t                       *name;
    ngx_stream_upstream_rr_peer_t   *peer, **peerp;
    ngx_stream_upstream_rr_peers_t  *peers, *backup;

    peers = ngx_slab_alloc(shpool, sizeof(ngx_stream_upstream_rr_peers_t));
    if (peers == NULL) {
        return NULL;
    }

    ngx_memcpy(peers, uscf->peer.data, sizeof(ngx_stream_upstream_rr_peers_t));

    name = ngx_slab_alloc(shpool, sizeof(ngx_str_t));
    if (name == NULL) {
        return NULL;
    }

    name->data = ngx_slab_alloc(shpool, peers->name->len);
    if (name->data == NULL) {
        return NULL;
    }

    ngx_memcpy(name->data, peers->name->data, peers->name->len);
    name->len = peers->name->len;

    peers->name = name;

    peers->shpool = shpool;

    for (peerp = &peers->peer; *peerp; peerp = &peer->next) {
        /* pool is unlocked */
        peer = ngx_stream_upstream_zone_copy_peer(peers, *peerp);
        if (peer == NULL) {
            return NULL;
        }

        *peerp = peer;
    }

    if (peers->next == NULL) {
        goto done;
    }

    backup = ngx_slab_alloc(shpool, sizeof(ngx_stream_upstream_rr_peers_t));
    if (backup == NULL) {
        return NULL;
    }

    ngx_memcpy(backup, peers->next, sizeof(ngx_stream_upstream_rr_peers_t));

    backup->name = name;

    backup->shpool = shpool;

    for (peerp = &backup->peer; *peerp; peerp = &peer->next) {
        /* pool is unlocked */
        peer = ngx_stream_upstream_zone_copy_peer(backup, *peerp);
        if (peer == NULL) {
            return NULL;
        }

        *peerp = peer;
    }

    peers->next = backup;

done:

    uscf->peer.data = peers;

    return peers;
}


static ngx_stream_upstream_rr_peer_t *
ngx_stream_upstream_zone_copy_peer(ngx_stream_upstream_rr_peers_t *peers,
    ngx_stream_upstream_rr_peer_t *src)
{
    ngx_slab_pool_t                *pool;
    ngx_stream_upstream_rr_peer_t  *dst;

    pool = peers->shpool;

    dst = ngx_slab_calloc_locked(pool, sizeof(ngx_stream_upstream_rr_peer_t));
    if (dst == NULL) {
        return NULL;
    }

    if (src) {
        ngx_memcpy(dst, src, sizeof(ngx_stream_upstream_rr_peer_t));
        dst->sockaddr = NULL;
        dst->name.data = NULL;
        dst->server.data = NULL;
    }

    dst->sockaddr = ngx_slab_calloc_locked(pool, NGX_SOCKADDRLEN);
    if (dst->sockaddr == NULL) {
        goto failed;
    }

    dst->name.data = ngx_slab_calloc_locked(pool, NGX_SOCKADDR_STRLEN);
    if (dst->name.data == NULL) {
        goto failed;
    }

    if (src) {
        ngx_memcpy(dst->sockaddr, src->sockaddr, src->socklen);
        ngx_memcpy(dst->name.data, src->name.data, src->name.len);

        dst->server.data = ngx_slab_alloc_locked(pool, src->server.len);
        if (dst->server.data == NULL) {
            goto failed;
        }

        ngx_memcpy(dst->server.data, src->server.data, src->server.len);
    }

    return dst;

failed:

    if (dst->server.data) {
        ngx_slab_free_locked(pool, dst->server.data);
    }

    if (dst->name.data) {
        ngx_slab_free_locked(pool, dst->name.data);
    }

    if (dst->sockaddr) {
        ngx_slab_free_locked(pool, dst->sockaddr);
    }

    ngx_slab_free_locked(pool, dst);

    return NULL;
}