1 进行echo模块的功能设计

以下是本模块要能识别的nginx配置

作为演示模块,我们这个模块仅仅完成以下功能:

读入nginx.conf中以echo开头的配置;echo是本模块新加入的命令,意思是直接输出; 例如:
在用户访问/hello时设置文件头为content-type=application/html;
在用户访问/hello时输出指定的欢迎词,比如“Hi,this is a demo module”;

2 准备nginx的源代码

可直接到[http://www.nginx.net/]下载,解压缩;

~#tar -xzf nginx-0.8.9.tar.gz

3 准备好nginx的配置文件,越简单越好,并且要打开调试,关闭daemon模式;

~#vim nginx.conf

worker_processes  1;
daemon off; 
master_process  off;
error_log  /tmp/error.log debug;
pid /tmp/nginx_demo.pid;
events {
    worker_connections  1024;
}
http {
    include       /etc/nginx/mime.types;
    sendfile        on;
    keepalive_timeout  65;
    tcp_nodelay        on;
    server {
        listen   8100;
        server_name  localhost;
        access_log  /tmp/access.log;
        error_log  /tmp/error.log debug;
        location /hello {
            echo "Hi,this is a demo module";
        }
    }
}

4 创建nginx模块目录

~#mkdir ngx_module_echo

5 编辑nginx模块的编译相关文件(config)

!#vim ngx_module_echo/config

其内容为:

ngx_addon_name=ngx_module_echo
HTTP_MODULES="$HTTP_MODULES ngx_module_echo"
NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_module_echo.c"
CORE_LIBS="$CORE_LIBS "
#CORE_LIBS="$CORE_LIBS -lm"

其实这里的意思也很好理解,这里告诉nginx编译的时候应该在哪里找到模块的源文件;这里指出了我们要包含进来的源文件是ngx_module_echo.c,编辑它,具体内容后面会给出:

#vim ngx_module_echo/ngx_module_echo.c

,然后试着配置一下nginx:

~#cd nginx-0.8.9
~/nginx-0.8.9/#./configure --add-module=~/ngx_module_echo/

,会报错:

./configure: error: no ~/ngx_module_echo//config was found

那是因为我们没有编辑好~/ngx_module_echo/ngx_module_echo.c这个文件,把它的内容改为:

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

static char* ngx_echo_readconf(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static void* ngx_echo_create_loc_conf(ngx_conf_t *cf);
static char* ngx_echo_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child);

typedef struct {
    ngx_str_t ecdata;
    ngx_flag_t           enable;
} ngx_echo_loc_conf_t;

static ngx_command_t  ngx_echo_commands[] = {
    { ngx_string("echo"),
      NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_echo_readconf,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_echo_loc_conf_t, ecdata),
      NULL },
      ngx_null_command
};


static ngx_http_module_t  ngx_echo_module_ctx = {
    NULL,                          /* preconfiguration */
    NULL,           /* postconfiguration */

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

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

    ngx_echo_create_loc_conf,  /* create location configuration */
    ngx_echo_merge_loc_conf /* merge location configuration */
};


ngx_module_t  ngx_module_echo = {
    NGX_MODULE_V1,
    &ngx_echo_module_ctx, /* module context */
    ngx_echo_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_echo_handler(ngx_http_request_t *r)
{
    printf("called:ngx_echo_handler\n");
    ngx_int_t     rc;
    ngx_buf_t    *b;
    ngx_chain_t   out;

    ngx_echo_loc_conf_t  *cglcf;
    cglcf = ngx_http_get_module_loc_conf(r, ngx_module_echo);

    if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) {
        return NGX_HTTP_NOT_ALLOWED;
    }
    if (r->headers_in.if_modified_since) {
        return NGX_HTTP_NOT_MODIFIED;
    }

    r->headers_out.content_type.len = sizeof("text/html") - 1;
    r->headers_out.content_type.data = (u_char *) "text/html";



    r->headers_out.status = NGX_HTTP_OK;
    r->headers_out.content_length_n = cglcf->ecdata.len;

    if (r->method == NGX_HTTP_HEAD) {
        rc = ngx_http_send_header(r);

        if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
            return rc;
        }
    }

    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
    if (b == NULL) {
    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "Failed to allocate
                  response buffer.");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    out.buf = b;
    out.next = NULL;


    b->pos = cglcf->ecdata.data;
    b->last = cglcf->ecdata.data+(cglcf->ecdata.len);

    b->memory = 1;
    b->last_buf = 1;
    rc = ngx_http_send_header(r);

    if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
        return rc;
    }
    return ngx_http_output_filter(r, &out);
}
static char *
ngx_echo_readconf(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    printf("called:ngx_echo_readconf\n");
    ngx_http_core_loc_conf_t  *clcf;

    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_echo_handler;
    ngx_conf_set_str_slot(cf,cmd,conf);
    return NGX_CONF_OK;
}


static void *
ngx_echo_create_loc_conf(ngx_conf_t *cf)
{
    printf("called:ngx_echo_create_loc_conf\n");
    ngx_echo_loc_conf_t  *conf;

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

    conf->ecdata.len=0;
    conf->ecdata.data=NULL;
    conf->enable = NGX_CONF_UNSET;
    return conf;
}
static char *
ngx_echo_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
    printf("called:ngx_echo_merge_loc_conf\n");
    ngx_echo_loc_conf_t *prev = parent;
    ngx_echo_loc_conf_t *conf = child;

    ngx_conf_merge_str_value(conf->ecdata, prev->ecdata, 10);
    ngx_conf_merge_value(conf->enable, prev->enable, 0);
/**
    if(conf->enable)
        ngx_echo_init(conf);
        */
    return NGX_CONF_OK;
    return NGX_CONF_OK;
}

下面好了,再回到nginx的源目录configure:

~/nginx-0.8.9/#./configure --add-module=/home/renlu/ngx_module_echo/ --with-
                                        debug
.... 这里省却输出;
make

然后运行一下看看,先测一下配置文件的正确性:

~/nginx-0.8.9/#./objs/nginx -c /home/renlu/ngx_module_echo/nginx.conf -t
called:ngx_echo_create_loc_conf
called:ngx_echo_create_loc_conf
called:ngx_echo_create_loc_conf
called:ngx_echo_readconf
called:ngx_echo_merge_loc_conf
called:ngx_echo_merge_loc_conf
the configuration file /home/renlu/ngx_module_echo/nginx.conf syntax is ok
configuration file /home/renlu/ngx_module_echo/nginx.conf test is successful

运行之:

~/nginx-0.8.9/#./objs/nginx -c /home/renlu/ngx_module_echo/nginx.conf
called:ngx_echo_create_loc_conf
called:ngx_echo_create_loc_conf
called:ngx_echo_create_loc_conf
called:ngx_echo_readconf
called:ngx_echo_merge_loc_conf
called:ngx_echo_merge_loc_conf

在另一个终端执行一个curl:

~#curl http://localhost:8100/hello
Hi,this is a demo module

好了,大功告成,nginx模块版的hello world就到这里了;

(责任编辑：IT)