handler模块的挂载
handler模块必须提供一个真正的处理函数,这个函数负责对来自客户端请求的真正处理。这个函数的处理,既可以选择自己直接生成内容,也可以选择拒绝处理,由后续的handler去进行处理,或者是选择丢给后续的filter进行处理。来看一下这个函数的原型申明。
typedef ngx_int_t (*ngx_http_handler_pt)(ngx_http_request_t *r);
r是http请求。该函数处理成功返回NGX_OK,处理发生错误返回NGX_ERROR,拒绝处理(留给后续的handler进行处理)返回NGX_DECLINE。 返回NGX_OK也就代表给客户端的响应已经生成好了,否则返回NGX_ERROR就发生错误了。
一种方式就是按处理阶段挂载;另外一种挂载方式就是按需挂载。
按处理阶段挂载
为了更精细地控制对于客户端请求的处理过程,nginx把这个处理过程划分成了11个阶段。他们从前到后,依次列举如下:
NGX_HTTP_POST_READ_PHASE: | |
---|---|
读取请求内容阶段 | |
NGX_HTTP_SERVER_REWRITE_PHASE: | |
Server请求地址重写阶段 | |
NGX_HTTP_FIND_CONFIG_PHASE: | |
配置查找阶段: | |
NGX_HTTP_REWRITE_PHASE: | |
Location请求地址重写阶段 | |
NGX_HTTP_POST_REWRITE_PHASE: | |
请求地址重写提交阶段 | |
NGX_HTTP_PREACCESS_PHASE: | |
访问权限检查准备阶段 | |
NGX_HTTP_ACCESS_PHASE: | |
访问权限检查阶段 | |
NGX_HTTP_POST_ACCESS_PHASE: | |
访问权限检查提交阶段 | |
NGX_HTTP_TRY_FILES_PHASE: | |
配置项try_files处理阶段 | |
NGX_HTTP_CONTENT_PHASE: | |
内容产生阶段 | |
NGX_HTTP_LOG_PHASE: | |
日志模块处理阶段 |
一般情况下,我们自定义的模块,大多数是挂载在NGX_HTTP_CONTENT_PHASE阶段的。挂载的动作一般是在模块上下文调用的postconfiguration函数中。
注意:有几个阶段是特例,它不调用挂载地任何的handler,也就是你就不用挂载到这几个阶段了:
- NGX_HTTP_FIND_CONFIG_PHASE
- NGX_HTTP_POST_ACCESS_PHASE
- NGX_HTTP_POST_REWRITE_PHASE
- NGX_HTTP_TRY_FILES_PHASE
例如一个挂载如下:
static ngx_int_t ngx_http_hello_init(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *cmcf; cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_hello_handler; return NGX_OK; }
使用这种方式挂载的handler也被称为 content phase handlers。
按需挂载
以这种方式挂载的handler也被称为 content handler。
当一个请求进来以后,nginx从NGX_HTTP_POST_READ_PHASE阶段开始依次执行每个阶段中所有handler。执行到 NGX_HTTP_CONTENT_PHASE阶段的时候,如果这个location有一个对应的content handler模块,那么就去执行这个content handler模块真正的处理函数。否则继续依次执行NGX_HTTP_CONTENT_PHASE阶段中所有content phase handlers,直到某个函数处理返回NGX_OK或者NGX_ERROR。
换句话说,当某个location处理到NGX_HTTP_CONTENT_PHASE阶段时,如果有content handler模块,那么NGX_HTTP_CONTENT_PHASE挂载的所有content phase handlers都不会被执行了。
举个例子来说:
static char * ngx_http_circle_gif(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_circle_gif_handler; return NGX_CONF_OK; }
下面是本书作者的模块代码:
#include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { ngx_str_t hello_string; ngx_int_t hello_counter; }ngx_http_hello_loc_conf_t; static ngx_int_t ngx_http_hello_init(ngx_conf_t *cf); static void *ngx_http_hello_create_loc_conf(ngx_conf_t *cf); static char *ngx_http_hello_string(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static char *ngx_http_hello_counter(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_command_t ngx_http_hello_commands[] = { { ngx_string("hello_string"), NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS|NGX_CONF_TAKE1, ngx_http_hello_string, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_hello_loc_conf_t, hello_string), NULL }, { ngx_string("hello_counter"), NGX_HTTP_LOC_CONF|NGX_CONF_FLAG, ngx_http_hello_counter, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_hello_loc_conf_t, hello_counter), NULL }, ngx_null_command }; /* static u_char ngx_hello_default_string[] = "Default String: Hello, world!"; */ static int ngx_hello_visited_times = 0; static ngx_http_module_t ngx_http_hello_module_ctx = { NULL, /* preconfiguration */ ngx_http_hello_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_hello_create_loc_conf, /* 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; ngx_http_hello_loc_conf_t* my_conf; u_char ngx_hello_string[1024] = {0}; ngx_uint_t content_length = 0; ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "ngx_http_hello_handler is called!"); my_conf = ngx_http_get_module_loc_conf(r, ngx_http_hello_module); if (my_conf->hello_string.len == 0 ) { ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "hello_string is empty!"); return NGX_DECLINED; } if (my_conf->hello_counter == NGX_CONF_UNSET || my_conf->hello_counter == 0) { ngx_sprintf(ngx_hello_string, "%s", my_conf->hello_string.data); } else { ngx_sprintf(ngx_hello_string, "%s Visited Times:%d", my_conf->hello_string.data, ++ngx_hello_visited_times); } ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "hello_string:%s", ngx_hello_string); content_length = ngx_strlen(ngx_hello_string); /* 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.data = (u_char *)"text/html"; */ ngx_str_set(&r->headers_out.content_type, "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 = content_length; 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 + content_length; 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 = content_length; /* 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 void *ngx_http_hello_create_loc_conf(ngx_conf_t *cf) { ngx_http_hello_loc_conf_t* local_conf = NULL; local_conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_hello_loc_conf_t)); if (local_conf == NULL) { return NULL; } ngx_str_null(&local_conf->hello_string); local_conf->hello_counter = NGX_CONF_UNSET; return local_conf; } /* static char *ngx_http_hello_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_hello_loc_conf_t* prev = parent; ngx_http_hello_loc_conf_t* conf = child; ngx_conf_merge_str_value(conf->hello_string, prev->hello_string, ngx_hello_default_string); ngx_conf_merge_value(conf->hello_counter, prev->hello_counter, 0); return NGX_CONF_OK; }*/ static char * ngx_http_hello_string(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_hello_loc_conf_t* local_conf; local_conf = conf; char* rv = ngx_conf_set_str_slot(cf, cmd, conf); ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "hello_string:%s", local_conf->hello_string.data); return rv; } static char *ngx_http_hello_counter(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_hello_loc_conf_t* local_conf; local_conf = conf; char* rv = NULL; rv = ngx_conf_set_flag_slot(cf, cmd, conf); ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "hello_counter:%d", local_conf->hello_counter); return rv; } static ngx_int_t ngx_http_hello_init(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *cmcf; cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_hello_handler; return NGX_OK; }