/*
 * Copyright (C) Joshua Zhu, http://www.zhuzhaoyuan.com
 */
 
 
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
 
 
typedef struct {
    ngx_flag_t                            enable;
    ngx_uint_t                            max_post_params;
} ngx_http_anti_hashdos_loc_conf_t;
 
 
typedef struct {
    ngx_uint_t                            post_params;
} ngx_http_anti_hashdos_ctx_t;
 
 
static ngx_int_t ngx_http_anti_hashdos_input_body_filter(ngx_http_request_t *r,
    ngx_buf_t *buf);
 
static void *ngx_http_anti_hashdos_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_anti_hashdos_merge_loc_conf(ngx_conf_t *cf, void *parent,
    void *child);
static ngx_int_t ngx_http_anti_hashdos_init(ngx_conf_t *cf);
 
 
static ngx_command_t ngx_http_anti_hashdos_filter_commands[] = {
 
    { ngx_string("anti_hashdos"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_anti_hashdos_loc_conf_t, enable),
      NULL },
 
    { ngx_string("anti_hashdos_max_post_params"),
      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_anti_hashdos_loc_conf_t, max_post_params),
      NULL },
 
      ngx_null_command
};
 
 
static ngx_http_module_t ngx_http_anti_hashdos_filter_module_ctx = {
    NULL,                                 /* preconfiguration */
    ngx_http_anti_hashdos_init,           /* postconfiguration */
 
    NULL,                                 /* create main configuration */
    NULL,                                 /* init main configuration */
 
    NULL,                                 /* create server configuration */
    NULL,                                 /* merge server configuration */
 
    ngx_http_anti_hashdos_create_loc_conf,/* create location configuration */
    ngx_http_anti_hashdos_merge_loc_conf  /* merge location configuration */
};
 
 
ngx_module_t ngx_http_anti_hashdos_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_anti_hashdos_filter_module_ctx, /* module context */
    ngx_http_anti_hashdos_filter_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_http_input_body_filter_pt  ngx_http_next_input_body_filter;
 
 
static ngx_int_t
ngx_http_anti_hashdos_input_body_filter(ngx_http_request_t *r,
    ngx_buf_t *buf)
{
    u_char                           *p;
    ngx_http_anti_hashdos_ctx_t      *ctx;
    ngx_http_anti_hashdos_loc_conf_t *ahlf;
 
    ahlf = ngx_http_get_module_loc_conf(r, ngx_http_anti_hashdos_filter_module);
 
    if (!ahlf->enable) {
        return ngx_http_next_input_body_filter(r, buf);
    }
 
    ctx = ngx_http_get_module_ctx(r, ngx_http_anti_hashdos_filter_module);
    if (ctx == NULL) {
        ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_anti_hashdos_ctx_t));
        if (ctx == NULL) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
 
        ctx->post_params = 1;
    }
 
    for (p = buf->pos; p < buf->last; p++) {
 
        if (*p == '&') {
            ctx->post_params++;
        }
    }
 
    if (ctx->post_params > ahlf->max_post_params) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "anti hashdos: \"%V\" blocked, too many post params: %d",
                      &r->connection->addr_text,
                      ctx->post_params);
        return NGX_HTTP_BAD_REQUEST;
    }
 
    return ngx_http_next_input_body_filter(r, buf);
}
 
 
static void *
ngx_http_anti_hashdos_create_loc_conf(ngx_conf_t *cf)
{
    ngx_http_anti_hashdos_loc_conf_t *conf;
 
    conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_anti_hashdos_loc_conf_t));
    if (conf == NULL) {
        return NULL;
    }
 
    conf->enable = NGX_CONF_UNSET;
    conf->max_post_params = NGX_CONF_UNSET_UINT;
 
    return conf;
}
 
 
static char *
ngx_http_anti_hashdos_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_anti_hashdos_loc_conf_t *prev = parent;
    ngx_http_anti_hashdos_loc_conf_t *conf = child;
 
    ngx_conf_merge_value(conf->enable, prev->enable, 0);
    ngx_conf_merge_uint_value(conf->max_post_params, prev->max_post_params,
                              120);
 
    return NGX_CONF_OK;
}
 
 
static ngx_int_t
ngx_http_anti_hashdos_init(ngx_conf_t *cf)
{
    ngx_http_next_input_body_filter = ngx_http_top_input_body_filter;
    ngx_http_top_input_body_filter = ngx_http_anti_hashdos_input_body_filter;
 
    return NGX_OK;
}

static ngx_int_t
ngx_http_anti_hashdos_input_body_filter(ngx_http_request_t *r, ngx_buf_t *buf)
{
    /* Do the input body filtering here */
}

static ngx_int_t
ngx_http_anti_hashdos_init(ngx_conf_t *cf)
{
    ngx_http_next_input_body_filter = ngx_http_top_input_body_filter;
    ngx_http_top_input_body_filter = ngx_http_anti_hashdos_input_body_filter;
 
    return NGX_OK;
}

# strace -o tracelog.txt -ff -T command

 
/*
 * Copyright (C) Joshua Zhu, http://www.zhuzhaoyuan.com
 */
 
 
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
 
 
static char *ngx_http_hello(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
 
static ngx_command_t ngx_http_hello_commands[] = {
    { ngx_string("hello"),
      NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS,
      ngx_http_hello,
      0,
      0,
      NULL },
 
    ngx_null_command
};
 
 
static u_char ngx_hello_string[] = "Hello, world!";
 
 
static ngx_http_module_t ngx_http_hello_module_ctx = {
    NULL,                          /* preconfiguration */
    NULL,                          /* postconfiguration */
 
    NULL,                          /* create main configuration */
    NULL,                          /* init main configuration */
 
    NULL,                          /* create server configuration */
    NULL,                          /* merge server configuration */
 
    NULL,                          /* create location configuration */
    NULL                           /* merge location configuration */
};
 
 
ngx_module_t ngx_http_hello_module = {
    NGX_MODULE_V1,
    &ngx_http_hello_module_ctx,    /* module context */
    ngx_http_hello_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_int_t
ngx_http_hello_handler(ngx_http_request_t *r)
{
    ngx_int_t    rc;
    ngx_buf_t   *b;
    ngx_chain_t  out;
 
    /* we response to 'GET' and 'HEAD' requests only */
    if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) {
        return NGX_HTTP_NOT_ALLOWED;
    }
 
    /* discard request body, since we don't need it here */
    rc = ngx_http_discard_request_body(r);
 
    if (rc != NGX_OK) {
        return rc;
    }
 
    /* set the 'Content-type' header */
    r->headers_out.content_type_len = sizeof("text/html") - 1;
    r->headers_out.content_type.len = sizeof("text/html") - 1;
    r->headers_out.content_type.data = (u_char *) "text/html";
 
    /* send the header only, if the request type is http 'HEAD' */
    if (r->method == NGX_HTTP_HEAD) {
        r->headers_out.status = NGX_HTTP_OK;
        r->headers_out.content_length_n = sizeof(ngx_hello_string) - 1;
 
        return ngx_http_send_header(r);
    }
 
    /* allocate a buffer for your response body */
    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
    if (b == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }
 
    /* attach this buffer to the buffer chain */
    out.buf = b;
    out.next = NULL;
 
    /* adjust the pointers of the buffer */
    b->pos = ngx_hello_string;
    b->last = ngx_hello_string + sizeof(ngx_hello_string) - 1;
    b->memory = 1;    /* this buffer is in memory */
    b->last_buf = 1;  /* this is the last buffer in the buffer chain */
 
    /* set the status line */
    r->headers_out.status = NGX_HTTP_OK;
    r->headers_out.content_length_n = sizeof(ngx_hello_string) - 1;
 
    /* send the headers of your response */
    rc = ngx_http_send_header(r);
 
    if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
        return rc;
    }
 
    /* send the buffer chain of your response */
    return ngx_http_output_filter(r, &out);
}
 
 
static char *
ngx_http_hello(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_loc_conf_t *clcf;
 
    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_http_hello_handler; /* handler to process the 'hello' directive */
 
    return NGX_CONF_OK;
}

ngx_addon_name=ngx_http_hello_module
HTTP_MODULES="$HTTP_MODULES ngx_http_hello_module"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_hello_module.c"

# hello
 
worker_processes 1;
 
events {
       worker_connections 1024;
}
 
http {
     server {
     	    listen 8080;
	    server_name localhost;
 
	    location / {
	    	     hello;
	    }
     }     
}

$ dstat -tcmn > stat.dat

#!/usr/bin/gnuplot
 
set terminal png
set output "cpu.png"
set title "CPU usage"
set xlabel "time"
set ylabel "percent"
set xdata time
set timefmt "%d-%m %H:%M:%S"
set format x "%H:%M"
plot "stat.dat" using 1:4 title "system" with lines, 
"stat.dat" using 1:3 title "user" with lines, 
"stat.dat" using 1:5 title "idle" with lines

#!/usr/bin/gnuplot
 
set terminal png
set output "memory.png"
set title "memory usage"
set xlabel "time"
set ylabel "size(M Bytes)"
set xdata time
set timefmt "%d-%m %H:%M:%S"
set format x "%H:%M"
plot "stat.dat" using 1:9 title "used" with lines, 
"stat.dat" using 1:10 title "buff" with lines, 
"stat.dat" using 1:11 title "cach" with lines, 
"stat.dat" using 1:12 title "free" with lines