nginx 模块开发，咱们先从模块分析入手，nginx的模块支持hook（钩子功能），我们可以在以下几个地方添加钩子：
- Just before the server reads the config file
读取配置文件时
- For every configuration directive for the location and server for which it appears;
读取到server或是location 配置的时候
- When Nginx initializes the main configuration
初始化主配置的时候
- When Nginx initializes the server (i.e., host/port) configuration
初始化server 配置的时候
- When Nginx merges the server configuration with the main configuration
使用主配置，合并server配置的时候
- When Nginx initializes the location configuration
初始化location配置的时候
- When Nginx merges the location configuration with its parent server configuration
使用server配置，合并location配置的时候
- When Nginx's master process starts
nginx 主进程启动的时候
- When a new worker process starts
nginx 启动一个新的工作进程的时候
- When a worker process exits
nginx 工作进程退出的时候
- When the master exits
nginx 主进程退出的时候
- Handling a request
接收的请求的时候
- Filtering response headers
过滤 response headers 的时候，gzip就是这个时候hook的
- Filtering the response body
过滤 response body 的时候，gzip就是这个时候hook的
- Picking a backend server
选择一个后台服务器的时候，在upstream 中选择
- Initiating a request to a backend server
初始化一个访问后台服务器的请求的时候
- Re-initiating a request to a backend server
重新初始化一个访问后台服务器的请求的时候
- Processing the response from a backend server
处理从后台返回的response的时候
- Finishing an interaction with a backend server
与后台服务器交互结束的时候
下面我们分析以下nginx memcache的模块，下载nginx源码，cd src/http/modules/，在moudels 目录下，你能找到nginx所有core modules ，这里我们分析ngx_http_memcached_module.c 文件
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
//配置定义
typedef struct {
ngx_http_upstream_conf_t upstream;
ngx_int_t index;
} ngx_http_memcached_loc_conf_t;
//request 定义
typedef struct {
size_t rest;
ngx_http_request_t *request;
ngx_str_t key;
} ngx_http_memcached_ctx_t;
已下是nginx 的 hood定义
static ngx_int_t ngx_http_memcached_create_request(ngx_http_request_t *r);
static ngx_int_t ngx_http_memcached_reinit_request(ngx_http_request_t *r);
static ngx_int_t ngx_http_memcached_process_header(ngx_http_request_t *r);
static ngx_int_t ngx_http_memcached_filter_init(void *data);
static ngx_int_t ngx_http_memcached_filter(void *data, ssize_t bytes);
static void ngx_http_memcached_abort_request(ngx_http_request_t *r);
static void ngx_http_memcached_finalize_request(ngx_http_request_t *r,
ngx_int_t rc);
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使用upstream 时定义的参数
static ngx_conf_bitmask_t ngx_http_memcached_next_upstream_masks[] = {
{ ngx_string("error"), NGX_HTTP_UPSTREAM_FT_ERROR },
{ ngx_string("timeout"), NGX_HTTP_UPSTREAM_FT_TIMEOUT },
{ ngx_string("invalid_response"), NGX_HTTP_UPSTREAM_FT_INVALID_HEADER },
{ ngx_string("not_found"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
{ ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
{ ngx_null_string, 0 }
};
memcache nginx 自定义命令
static ngx_command_t ngx_http_memcached_commands[] = {
{ ngx_string("memcached_pass"),
NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF|NGX_CONF_TAKE1,
ngx_http_memcached_pass,
NGX_HTTP_LOC_CONF_OFFSET,
0,
NULL },
{ ngx_string("memcached_bind"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
ngx_http_upstream_bind_set_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_memcached_loc_conf_t, upstream.local),
NULL },
{ ngx_string("memcached_connect_timeout"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_memcached_loc_conf_t, upstream.connect_timeout),
NULL },
{ ngx_string("memcached_send_timeout"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_memcached_loc_conf_t, upstream.send_timeout),
NULL },
{ ngx_string("memcached_buffer_size"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
ngx_conf_set_size_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_memcached_loc_conf_t, upstream.buffer_size),
NULL },
{ ngx_string("memcached_read_timeout"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
ngx_conf_set_msec_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_memcached_loc_conf_t, upstream.read_timeout),
NULL },
{ ngx_string("memcached_next_upstream"),
NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
ngx_conf_set_bitmask_slot,
NGX_HTTP_LOC_CONF_OFFSET,
offsetof(ngx_http_memcached_loc_conf_t, upstream.next_upstream),
&ngx_http_memcached_next_upstream_masks },
ngx_null_command
};
Nginx 命令结构
struct ngx_command_s {
ngx_str_t name;
ngx_uint_t type;
char *(*set)(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
ngx_uint_t conf;
ngx_uint_t offset;
void *post;
};
自定义命令配置说明：
type ：
NGX_HTTP_MAIN_CONF：可出现在 http 的主作用域；
NGX_HTTP_SRV_CONF：可出现在 http 的 server 作用域；
NGX_HTTP_LOC_CONF：可出现在 http 的 location 作用域；
NGX_HTTP_UPS_CONF：可出现在 http 的 upstream 作用域；
NGX_HTTP_SIF_CONF：可出现在判断语句里；
NGX_CONF_NOARGS：指令没有参数；
NGX_CONF_TAKE1：指令读入1个参数；
NGX_CONF_TAKE2：指令读入2个参数；
......
NGX_CONF_TAKE7：指令读入7个参数；
NGX_CONF_FLAG： 指令读入1个布尔型数据（“on”或“off”）；
NGX_CONF_1MORE：指令至少读入1个参数；
NGX_CONF_2MORE：指令至少读入2个参数；
http 上下文定义：
-
static ngx_http_module_t ngx_http_memcached_module_ctx = { NULL, /* preconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_memcached_create_loc_conf, /* create location configuration */ ngx_http_memcached_merge_loc_conf /* merge location configuration */ }; ngx_module_t ngx_http_memcached_module = { NGX_MODULE_V1, &ngx_http_memcached_module_ctx, /* module context */ ngx_http_memcached_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 };http 上下文结构定义：
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;我们跟进看一下 create and merge loc config：
static void * ngx_http_memcached_create_loc_conf(ngx_conf_t *cf) { ngx_http_memcached_loc_conf_t *conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_memcached_loc_conf_t)); if (conf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->upstream.bufs.num = 0; * conf->upstream.next_upstream = 0; * conf->upstream.temp_path = NULL; * conf->upstream.uri = { 0, NULL }; * conf->upstream.location = NULL; */ conf->upstream.connect_timeout = NGX_CONF_UNSET_MSEC; conf->upstream.send_timeout = NGX_CONF_UNSET_MSEC; conf->upstream.read_timeout = NGX_CONF_UNSET_MSEC; conf->upstream.buffer_size = NGX_CONF_UNSET_SIZE; /* the hardcoded values */ conf->upstream.cyclic_temp_file = 0; conf->upstream.buffering = 0; conf->upstream.ignore_client_abort = 0; conf->upstream.send_lowat = 0; conf->upstream.bufs.num = 0; conf->upstream.busy_buffers_size = 0; conf->upstream.max_temp_file_size = 0; conf->upstream.temp_file_write_size = 0; conf->upstream.intercept_errors = 1; conf->upstream.intercept_404 = 1; conf->upstream.pass_request_headers = 0; conf->upstream.pass_request_body = 0; conf->index = NGX_CONF_UNSET; return conf; } static char * ngx_http_memcached_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_memcached_loc_conf_t *prev = parent; ngx_http_memcached_loc_conf_t *conf = child; ngx_conf_merge_msec_value(conf->upstream.connect_timeout, prev->upstream.connect_timeout, 60000); ngx_conf_merge_msec_value(conf->upstream.send_timeout, prev->upstream.send_timeout, 60000); ngx_conf_merge_msec_value(conf->upstream.read_timeout, prev->upstream.read_timeout, 60000); ngx_conf_merge_size_value(conf->upstream.buffer_size, prev->upstream.buffer_size, (size_t) ngx_pagesize); ngx_conf_merge_bitmask_value(conf->upstream.next_upstream, prev->upstream.next_upstream, (NGX_CONF_BITMASK_SET |NGX_HTTP_UPSTREAM_FT_ERROR |NGX_HTTP_UPSTREAM_FT_TIMEOUT)); if (conf->upstream.next_upstream & NGX_HTTP_UPSTREAM_FT_OFF) { conf->upstream.next_upstream = NGX_CONF_BITMASK_SET |NGX_HTTP_UPSTREAM_FT_OFF; } if (conf->upstream.upstream == NULL) { conf->upstream.upstream = prev->upstream.upstream; } if (conf->index == NGX_CONF_UNSET) { conf->index = prev->index; } return NGX_CONF_OK; }
接下来我们进入handler：static char * ngx_http_memcached_pass(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module); clcf->handler = ngx_http_memcached_handler; return NGX_CONF_OK; }static ngx_int_t ngx_http_memcached_handler(ngx_http_request_t *r) { ngx_int_t rc; ngx_http_upstream_t *u; ngx_http_memcached_ctx_t *ctx; ngx_http_memcached_loc_conf_t *mlcf; if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) { return NGX_HTTP_NOT_ALLOWED; } rc = ngx_http_discard_request_body(r); if (rc != NGX_OK) { return rc; } if (ngx_http_set_content_type(r) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (ngx_http_upstream_create(r) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } u = r->upstream; ngx_str_set(&u->schema, "memcached://"); u->output.tag = (ngx_buf_tag_t) &ngx_http_memcached_module; mlcf = ngx_http_get_module_loc_conf(r, ngx_http_memcached_module); u->conf = &mlcf->upstream; u->create_request = ngx_http_memcached_create_request; u->reinit_request = ngx_http_memcached_reinit_request; u->process_header = ngx_http_memcached_process_header; u->abort_request = ngx_http_memcached_abort_request; u->finalize_request = ngx_http_memcached_finalize_request; ctx = ngx_palloc(r->pool, sizeof(ngx_http_memcached_ctx_t)); if (ctx == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } ctx->rest = NGX_HTTP_MEMCACHED_END; ctx->request = r; ngx_http_set_ctx(r, ctx, ngx_http_memcached_module); u->input_filter_init = ngx_http_memcached_filter_init; u->input_filter = ngx_http_memcached_filter; u->input_filter_ctx = ctx; r->main->count++; ngx_http_upstream_init(r); return NGX_DONE; }以上 memcache处理均在以下方法中进行：u->create_request = ngx_http_memcached_create_request; u->reinit_request = ngx_http_memcached_reinit_request; u->process_header = ngx_http_memcached_process_header; u->abort_request = ngx_http_memcached_abort_request; u->finalize_request = ngx_http_memcached_finalize_request;u->input_filter_init = ngx_http_memcached_filter_init; u->input_filter = ngx_http_memcached_filter; u->input_filter_ctx = ctx;
以上是对memcached nginx模块进行的分析，小刀我也是初始，有写的不好的地方，请大家多多指教，接下来我们在看一个 not modified moudel 这个相对就容易很多。/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static ngx_int_t ngx_http_test_precondition(ngx_http_request_t *r); static ngx_int_t ngx_http_test_not_modified(ngx_http_request_t *r); static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf); static ngx_http_module_t ngx_http_not_modified_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_not_modified_filter_init, /* 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_not_modified_filter_module = { NGX_MODULE_V1, &ngx_http_not_modified_filter_module_ctx, /* module context */ NULL, /* 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_output_header_filter_pt ngx_http_next_header_filter; static ngx_int_t ngx_http_not_modified_header_filter(ngx_http_request_t *r) { if (r->headers_out.status != NGX_HTTP_OK || r != r->main || r->headers_out.last_modified_time == -1) { return ngx_http_next_header_filter(r); } if (r->headers_in.if_unmodified_since) { return ngx_http_test_precondition(r); } if (r->headers_in.if_modified_since) { return ngx_http_test_not_modified(r); } return ngx_http_next_header_filter(r); } static ngx_int_t ngx_http_test_precondition(ngx_http_request_t *r) { time_t iums; iums = ngx_http_parse_time(r->headers_in.if_unmodified_since->value.data, r->headers_in.if_unmodified_since->value.len); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http iums:%d lm:%d", iums, r->headers_out.last_modified_time); if (iums >= r->headers_out.last_modified_time) { return ngx_http_next_header_filter(r); } return ngx_http_filter_finalize_request(r, NULL, NGX_HTTP_PRECONDITION_FAILED); } static ngx_int_t ngx_http_test_not_modified(ngx_http_request_t *r) { time_t ims; ngx_http_core_loc_conf_t *clcf; clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) { return ngx_http_next_header_filter(r); } ims = ngx_http_parse_time(r->headers_in.if_modified_since->value.data, r->headers_in.if_modified_since->value.len); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http ims:%d lm:%d", ims, r->headers_out.last_modified_time); if (ims != r->headers_out.last_modified_time) { if (clcf->if_modified_since == NGX_HTTP_IMS_EXACT || ims < r->headers_out.last_modified_time) { return ngx_http_next_header_filter(r); } } r->headers_out.status = NGX_HTTP_NOT_MODIFIED; r->headers_out.status_line.len = 0; r->headers_out.content_type.len = 0; ngx_http_clear_content_length(r); ngx_http_clear_accept_ranges(r); if (r->headers_out.content_encoding) { r->headers_out.content_encoding->hash = 0; r->headers_out.content_encoding = NULL; } return ngx_http_next_header_filter(r); } static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_not_modified_header_filter; return NGX_OK; }自定义返回时设置cookie：
1. mkdir author2. cd author3. 创建一个文件叫 config 内容如下
ngx_addon_name=nginx_add_author_filter_module HTTP_AUX_FILTER_MODULES="$HTTP_AUX_FILTER_MODULES nginx_add_author_filter_module" NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/author.c"
4../configure --add-module=/Users/liuzheng/nginx/addOn/
/* * Copy right (C) Liuzheng Wiyun author.c */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static ngx_int_t ngx_http_add_author_filter_init(ngx_conf_t *cf); static ngx_int_t ngx_http_add_author_header_filter(ngx_http_request_t *r); static ngx_http_module_t nginx_add_author_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_add_author_filter_init, /* 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 nginx_add_author_filter_module = { NGX_MODULE_V1, &nginx_add_author_filter_module_ctx, /* module context */ NULL, /* 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_output_header_filter_pt ngx_http_next_header_filter; static ngx_int_t ngx_http_add_author_header_filter(ngx_http_request_t *r) { ngx_table_elt_t *set_cookie; set_cookie = ngx_list_push(&r->headers_out.headers); if (set_cookie == NULL) { return NGX_ERROR; } set_cookie->hash = 1; ngx_str_set(&set_cookie->key, "Set-Cookie"); ngx_str_set(&set_cookie->value, "author=liuzheng"); return ngx_http_next_header_filter(r); } static ngx_int_t ngx_http_add_author_filter_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_add_author_header_filter; return NGX_OK; }