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后端技术_Nginx过滤器模块实现

最近更新：2024-09-23 | 字数总计：1.1k | 阅读估时：5分钟 | 阅读量：次

黑白名单
nginx组件使用
过滤器模块实现
1. ngnix模块
2. 过滤器模块

黑白名单

限制哪些ip（tcp连接）
限制资源访问（http头）
用户（http体）

nginx组件使用

可以抽出的可供使用及研究的组件：

内存池
线程池
共享内存
ngx_array_t
ngx_list_t
ngx_hash_t
ngx_rbtree_t
ngx_queue_t
原子操作
日志
slab
ngx_str_t

ngx_str_t

// gcc -o ngx_str_code ngx_str_code.c -I /home/king/share/nginx/nginx-1.22.1/src/core -I /home/king/share/nginx/nginx-1.22.1/obj/
// -I /home/king/share/nginx/nginx-1.22.1/src/core/os/unix/ -I /home/king/share/nginx/pcre-8.45
##include <ngx_files.h>
##include <ngx_core.h>
##include <ngx_palloc.h>
##include <ngx_log.h>
##include <ngx_string.h>

##define unused(x) x = x

volatile ngx_cycle_t *ngx_cycle;

void ngx_log_error_core(ngx_uint_t level, ngx_log_t *log, ngx_err_t err, const char* fmt,...){
    unused(level);
    unused(log);
    unused(err);
    unused(fmt);
}

int main()
{
    ngx_str_t name = ngx_string("king");
    printf("name --> len:% ld, data: %s\n", name.len, name.data);
}

内存池

// gcc -o ngx_str_code ngx_str_code.c -I /home/king/share/nginx/nginx-1.22.1/src/core -I /home/king/share/nginx/nginx-1.22.1/obj/
// -I /home/king/share/nginx/nginx-1.22.1/src/core/os/unix/ -I /home/king/share/nginx/pcre-8.45
##include <ngx_files.h>
##include <ngx_core.h>
##include <ngx_palloc.h>
##include <ngx_log.h>
##include <ngx_string.h>

##define unused(x) x = x

volatile ngx_cycle_t *ngx_cycle;

void ngx_log_error_core(ngx_uint_t level, ngx_log_t *log, ngx_err_t err, const char* fmt,...){
    unused(level);
    unused(log);
    unused(err);
    unused(fmt);
}

void print_pool(ngx_pool_t * pool){
    // end指向内存池末尾
    // last指向下一次分配的头
    printf("last: %p, end: %p\n", pool->d.last, pool->d.end);
}

int main()
{
    ngx_pool_t *pool = ngx_create_pool(1024, NULL);
    print_pool(pool);
    int* p1 = ngx_palloc(pool, sizeof(int));
    print_pool(pool);
    void *p2 = ngx_palloc(pool, 10);
    print_pool(pool);
    void *p3 = ngx_palloc(pool, 10);
    print_pool(pool);

    ngx_destroy_pool(pool);
}

共享内存

ngx_array_t

ngx_list_t

ngx_hash_t

ngx_rbtree_t

ngx_queue_t

原子操作

过滤器模块实现

ngnix模块

upstream（代理，从浏览器->nginx->backend server->mysql）
filter（回数据时添加内容，从backend server->nginx->浏览器）
handler（一个来回过程）

过滤器模块

举例：从backend后端返回网页给nginx，在其中添加广告再返回给客户端

nginx_filter_module.c

typedef struct {
    ngx_flag_t enable;
} ngx_http_zvoice_filter_conf_t;

static ngx_command_t ngx_http_zvoice_filter_module_commands[] = {
    {
        ngx_string("zvoice"), // 在conf中的名称
        NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOG_CONF | NGX_CONF_FLAG, // 该配置可以写在哪里？
        // http层 or server层 or location层 ， 可以设置on或者off
        ngx_conf_set_flag_slot, // 使用set flag的on off来触发回调
        NGX_HTTP_LOG_CONF_OFFSET,
        offsetof(ngx_http_zvoice_filter_conf_t, enable), // 使用ngx_http_zvoice_filter_conf_t这个变量来传入ngx_conf_set_flag_slot，并说明on或者off存储的位置是哪个变量
        NULL
    },
    ngx_null_command // 因为用了一个没有长度的数组，所以要标识结束，必须写
};

/*
！！ngx_http_module_t中并没有实现业务操作，而是实现了从conf文件中读取配置，真正实现了配置和nginx的结合，实现了conf文件业务编程的功能
typedef struct {
    ngx_int_t   (*preconfiguration)(ngx_conf_t *cf);
    ngx_int_t   (*postconfiguration)(ngx_conf_t *cf);

    void       *(*create_main_conf)(ngx_conf_t *cf);
    char       *(*init_main_conf)(ngx_conf_t *cf, void *conf);

    void       *(*create_srv_conf)(ngx_conf_t *cf);
    char       *(*merge_srv_conf)(ngx_conf_t *cf, void *prev, void *conf);

    void       *(*create_loc_conf)(ngx_conf_t *cf);
    char       *(*merge_loc_conf)(ngx_conf_t *cf, void *prev, void *conf);
} ngx_http_module_t;
*/


static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
static ngx_http_output_body_filter_pt ngx_http_next_body_filter;

static ngx_int_t ngx_http_prefix_filter_header_filter(ngx_http_request_t *r) { // 自己实现的header过滤器
    ngx_http_prefix_filter_ctx_t *ctx;
	ngx_http_prefix_filter_conf_t *conf;

	if (r->headers_out.status != NGX_HTTP_OK) {
		return ngx_http_next_header_filter(r);
	}

	ctx = ngx_http_get_module_ctx(r, ngx_http_prefix_filter_module);
	if (ctx) {
		return ngx_http_next_header_filter(r);
	}

	conf = ngx_http_get_module_loc_conf(r, ngx_http_prefix_filter_module);
	if (conf == NULL) {
		return ngx_http_next_header_filter(r);
	}
	if (conf->enable == 0) {
		return ngx_http_next_header_filter(r);
	}


	ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_prefix_filter_ctx_t));
	if (ctx == NULL) {
		return NGX_ERROR;
	}
	ctx->add_prefix = 0;

	ngx_http_set_ctx(r, ctx, ngx_http_prefix_filter_module);

	if (r->headers_out.content_type.len >= sizeof("text/html") - 1
		&& ngx_strncasecmp(r->headers_out.content_type.data, (u_char*)"text/html", sizeof("text/html")-1) == 0) {

		ctx->add_prefix = 1;
		if (r->headers_out.content_length_n > 0) {
			r->headers_out.content_length_n += filter_prefix.len;
		}
	}

	return ngx_http_prefix_filter_header_filter(r);
}

static ngx_int_t ngx_http_prefix_filter_body_filter(ngx_http_request_t *r, ngx_chain_t *in) { // 自己实现的body过滤器
    gx_http_prefix_filter_ctx_t *ctx = ngx_http_get_module_ctx(r, ngx_http_prefix_filter_module);
	if (ctx == NULL || ctx->add_prefix != 1) {
		return ngx_http_next_body_filter(r, in);
	}
	
	ctx->add_prefix = 2;

	ngx_buf_t *b = ngx_create_temp_buf(r->pool, filter_prefix.len);
	b->start = b->pos = filter_prefix.data;
	b->last = b->pos + filter_prefix.len;

	ngx_chain_t *cl = ngx_alloc_chain_link(r->pool);
	cl->buf = b;
	cl->next = in;
	return ngx_http_next_body_filter(r, cl);
}


ngx_int_t   ngx_http_zvoice_filter_postconfiguration(ngx_conf_t *cf)
{
    // 头插法
    ngx_http_next_header_filter = ngx_http_top_header_filter;
	ngx_http_top_header_filter = ngx_http_prefix_filter_header_filter;

	ngx_http_next_body_filter = ngx_http_top_body_filter;
	ngx_http_top_body_filter = ngx_http_prefix_filter_body_filter;

	return NGX_OK;
}


void  *ngx_http_zvoice_filter_create_loc_conf(ngx_conf_t *cf){
    // 进入到location时，读取zvoice的值
    ngx_http_zvoice_filter_conf_t *conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_zvoice_filter_conf_t));
    if(conf == NULL) return NULL;
    conf->enable = NGX_CONF_UNSET;
    return conf;
}
char  *ngx_http_zvoice_filter_merge_loc_conf(ngx_conf_t *cf, void *prev, void *child)
{
    ngx_http_zvoice_filter_conf_t *prev = (ngx_http_zvoice_filter_conf_t*)parent;
    ngx_http_zvoice_filter_conf_t *conf = (ngx_http_zvoice_filter_conf_t*)child;

    ngx_conf_merge_value(conf->enable, prev->enable, 0); // 前面那个有设置嘛？没有就将后面的一项设置给前面
    return NGX_CONF_OK;
}

static ngx_http_module_t ngx_http_zvoice_filter_module_ctx = { // 写成static，规定定义作用域防止重名
    // conf
    NULL, ngx_http_zvoice_filter_postconfiguration
    // main
    NULL, NULL
    // server
    NULL, NULL
    // location
    ngx_http_zvoice_filter_create_loc_conf,
    ngx_http_zvoice_filter_merge_loc_conf
};

ngx_module_t ngx_http_zvoice_filter_module = { // 这个名字不能错
    NGX_MODULE_V1, // 默认的，可以用来填充模块前部
    // ===============================================重要
    &ngx_http_zvoice_filter_module_ctx, // 模块的ctx
    ngx_http_zvoice_filter_module_commands, // command
    NGX_HTTP_MODULE, // http模块
    // ===============================================重要
    NULL,NULL,NULL,NULL, // 这些都是init各种阶段可以添加的回调
    NULL,NULL,NULL,
    NGX_MODULE_V1_PADDING // 固定可以用来填充的保留位置
};

config（固定写法，不要使用windows去写，因为文件格式不对）

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ngx_addon_name=ngx_http_zvoice_filter_module
HTTP_FILTER_MODULES="$HTTP_FILTER_MODULES ngx_http_zvoice_filter_module"
NGX_ADDON_SRCS="NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_zvoice_filter_module.c"

configure添加模块

1	./configure --prefix=/usr/local/nginx ...... --add-module=/home/king/share/nginx/ngx_code_test/ngx_http_zvoice_filter_module

2024-03-13 该篇文章被 Cleofwine 归为分类: 服务端