nginx模块开发

这个模块的功能是向client发送一个文件，类似于网页上的另存为功能
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>

static ngx_int_t ngx_http_file_init(ngx_conf_t *cf);
void* ngx_http_file_create_loc_conf(ngx_conf_t *cf);
static char* ngx_http_file_name(ngx_conf_t* cf,ngx_command_t* cmd,void* conf);

typedef struct
{
	ngx_str_t file_name;
}ngx_http_file_loc_conf_t;

static ngx_http_module_t ngx_http_file_module_ctx = 
{
	NULL,
	ngx_http_file_init,				    /* postconfiguration */
	NULL,
	NULL,
	NULL,
	NULL,
	ngx_http_file_create_loc_conf,	    /*  create location configuration */
	NULL
};

static ngx_command_t ngx_http_file_commands[] = {
	{
		ngx_string("file_name"),
		NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS|NGX_CONF_TAKE1,/* 接收0个或1个參数 */
		ngx_http_file_name,
		NGX_HTTP_LOC_CONF_OFFSET,						 /* 配置项的级别 */
		offsetof(ngx_http_file_loc_conf_t, file_name),	 /*file_name配置项在ngx_http_file_loc_conf_t中的偏移位置*/	
		NULL,
	},
	ngx_null_command
};

/* 模块的定义 */
ngx_module_t ngx_http_file_module = 
{
	NGX_MODULE_V1,
	&ngx_http_file_module_ctx,			/* 模块上下文，即一些回调函数 */
	ngx_http_file_commands,				/* 配置项解析 */
	NGX_HTTP_MODULE,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NULL,
	NGX_MODULE_V1_PADDING
};

static ngx_int_t ngx_http_file_handler(ngx_http_request_t* r)
{
	ngx_http_core_loc_conf_t  *clcf = ngx_http_get_module_loc_conf(r,ngx_http_core_module);
	ngx_http_file_loc_conf_t* file_conf = ngx_http_get_module_loc_conf(r,ngx_http_file_module);//获得配置项结构体
	if(file_conf -> file_name.len == 0)
	{
		ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0,"file_name is empty");
		return NGX_DECLINED;
	}

	ngx_open_file_info_t of;//文件信息结构体
	ngx_str_t path = file_conf->file_name;
	ngx_memzero(&of, sizeof(ngx_open_file_info_t));
	if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool)!= NGX_OK)
	{
		ngx_log_error(NGX_LOG_ERR,r->connection->log,of.err, "%s "%s" failed", of.failed, path.data);
	}

	ngx_int_t rc = ngx_http_discard_request_body(r);//丢弃包体
	if(rc != NGX_OK)return rc;

	r -> headers_out.status =  NGX_HTTP_OK;
	r -> headers_out.content_length_n = of.size;
	r -> headers_out.last_modified_time = of.mtime;
	if(ngx_http_set_etag(r) != NGX_OK)return NGX_HTTP_INTERNAL_SERVER_ERROR;
	if(ngx_http_set_content_type(r) != NGX_OK)return NGX_HTTP_INTERNAL_SERVER_ERROR;

	r -> allow_ranges = 1;
	/* 先申请发送包体的缓冲区空间，申请成功后再发送包头 */
	ngx_buf_t* b = ngx_pcalloc(r -> pool,sizeof(ngx_buf_t));
	if(b == NULL)return NGX_HTTP_INTERNAL_SERVER_ERROR;
	b -> file = ngx_pcalloc(r -> pool,sizeof(ngx_file_t));
	if(b->file == NULL)return NGX_HTTP_INTERNAL_SERVER_ERROR;

	rc = ngx_http_send_header(r); /* 发送头部 */
	if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) return rc;

	b -> file_pos = 0;
	b -> file_last = of.size;
	b -> in_file = b -> file_last ? 1 : 0;
	b -> last_buf = (r == r -> main) ? 1 : 0;
	b -> last_in_chain = 1;
	b -> file -> name = path;
	b -> file -> fd = of.fd;

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

	return ngx_http_output_filter(r,&out); /*把产生的内容传递给兴许的filter去处理 */

}

/* 创建配置项结构体 */
void* ngx_http_file_create_loc_conf(ngx_conf_t *cf)
{
	ngx_http_file_loc_conf_t* local_conf = ngx_pcalloc(cf->pool,sizeof(ngx_http_file_loc_conf_t));
	if(local_conf == NULL)return NULL;
	ngx_str_null(&local_conf->file_name);
	return local_conf;
}

/* cf: 该參数里面保存从配置文件读取到的原始字符串以及相关的一些信息
 * cmd: 这个配置指令相应的ngx_command_t结构，即上面定义的数组中的第一个元素
 * conf: 就是定义的存储这个配置值的结构体，即上面的ngx_http_file_loc_conf_t*/
static char* ngx_http_file_name(ngx_conf_t* cf,ngx_command_t* cmd,void* conf)
{
	/* cf表示已经解析好的參数信息，将当中的数据取出来赋给自定义的配置项结构体中的相应成员 */
	char* rv = ngx_conf_set_str_slot(cf,cmd,conf);
	return rv;
}

static ngx_int_t ngx_http_file_init(ngx_conf_t *cf)
{
	ngx_http_core_main_conf_t* cmcf = ngx_http_conf_get_module_main_conf(cf,ngx_http_core_module);//获得核心配置文件
	ngx_http_handler_pt* h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers);//将handler增加handlers链表
	if(h == NULL)return NGX_ERROR;
	*h = ngx_http_file_handler;//对该handler方法进行赋值
	return NGX_OK;
}
用法：
编译：还须要在file_module目录中加入config文件
./configure --prefix=/home/fangjian/study/code/nginx-1.4.4/nginx --add-module=/home/fangjian/study/code/nginx-1.4.4/fangjian_module/file_module
make
make install
然后在nginx.conf中加入 location /file {file_name index.html; }启动nginx，在浏览器中输入127.0.0.1/file