view src/stream/ngx_stream_return_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 56fc55e32f23
children
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/*
 * Copyright (C) Roman Arutyunyan
 * Copyright (C) Nginx, Inc.
 */


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


typedef struct {
    ngx_stream_complex_value_t   text;
} ngx_stream_return_srv_conf_t;


typedef struct {
    ngx_chain_t                 *out;
} ngx_stream_return_ctx_t;


static void ngx_stream_return_handler(ngx_stream_session_t *s);
static void ngx_stream_return_write_handler(ngx_event_t *ev);

static void *ngx_stream_return_create_srv_conf(ngx_conf_t *cf);
static char *ngx_stream_return(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);


static ngx_command_t  ngx_stream_return_commands[] = {

    { ngx_string("return"),
      NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
      ngx_stream_return,
      NGX_STREAM_SRV_CONF_OFFSET,
      0,
      NULL },

      ngx_null_command
};


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

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

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


ngx_module_t  ngx_stream_return_module = {
    NGX_MODULE_V1,
    &ngx_stream_return_module_ctx,         /* module context */
    ngx_stream_return_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 void
ngx_stream_return_handler(ngx_stream_session_t *s)
{
    ngx_str_t                      text;
    ngx_buf_t                     *b;
    ngx_connection_t              *c;
    ngx_stream_return_ctx_t       *ctx;
    ngx_stream_return_srv_conf_t  *rscf;

    c = s->connection;

    c->log->action = "returning text";

    rscf = ngx_stream_get_module_srv_conf(s, ngx_stream_return_module);

    if (ngx_stream_complex_value(s, &rscf->text, &text) != NGX_OK) {
        ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
        return;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_STREAM, c->log, 0,
                   "stream return text: \"%V\"", &text);

    if (text.len == 0) {
        ngx_stream_finalize_session(s, NGX_STREAM_OK);
        return;
    }

    ctx = ngx_pcalloc(c->pool, sizeof(ngx_stream_return_ctx_t));
    if (ctx == NULL) {
        ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
        return;
    }

    ngx_stream_set_ctx(s, ctx, ngx_stream_return_module);

    b = ngx_calloc_buf(c->pool);
    if (b == NULL) {
        ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
        return;
    }

    b->memory = 1;
    b->pos = text.data;
    b->last = text.data + text.len;
    b->last_buf = 1;

    ctx->out = ngx_alloc_chain_link(c->pool);
    if (ctx->out == NULL) {
        ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
        return;
    }

    ctx->out->buf = b;
    ctx->out->next = NULL;

    c->write->handler = ngx_stream_return_write_handler;

    ngx_stream_return_write_handler(c->write);
}


static void
ngx_stream_return_write_handler(ngx_event_t *ev)
{
    ngx_connection_t         *c;
    ngx_stream_session_t     *s;
    ngx_stream_return_ctx_t  *ctx;

    c = ev->data;
    s = c->data;

    if (ev->timedout) {
        ngx_connection_error(c, NGX_ETIMEDOUT, "connection timed out");
        ngx_stream_finalize_session(s, NGX_STREAM_OK);
        return;
    }

    ctx = ngx_stream_get_module_ctx(s, ngx_stream_return_module);

    if (ngx_stream_top_filter(s, ctx->out, 1) == NGX_ERROR) {
        ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
        return;
    }

    ctx->out = NULL;

    if (!c->buffered) {
        ngx_log_debug0(NGX_LOG_DEBUG_STREAM, c->log, 0,
                       "stream return done sending");
        ngx_stream_finalize_session(s, NGX_STREAM_OK);
        return;
    }

    if (ngx_handle_write_event(ev, 0) != NGX_OK) {
        ngx_stream_finalize_session(s, NGX_STREAM_INTERNAL_SERVER_ERROR);
        return;
    }

    ngx_add_timer(ev, 5000);
}


static void *
ngx_stream_return_create_srv_conf(ngx_conf_t *cf)
{
    ngx_stream_return_srv_conf_t  *conf;

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

    return conf;
}


static char *
ngx_stream_return(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_stream_return_srv_conf_t *rscf = conf;

    ngx_str_t                           *value;
    ngx_stream_core_srv_conf_t          *cscf;
    ngx_stream_compile_complex_value_t   ccv;

    if (rscf->text.value.data) {
        return "is duplicate";
    }

    value = cf->args->elts;

    ngx_memzero(&ccv, sizeof(ngx_stream_compile_complex_value_t));

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

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

    cscf = ngx_stream_conf_get_module_srv_conf(cf, ngx_stream_core_module);

    cscf->handler = ngx_stream_return_handler;

    return NGX_CONF_OK;
}