nginx模块开发流程

* 编写模块基本结构：模块配置结构/模块配置指令/模块上下文结构/模块的定义

** 模块配置结构定义

typedef struct

{

ngx_str_t hello_string;

ngx_int_t hello_counter;

}ngx_http_hello_loc_conf_t;

** 模块配置指令定义

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

};

** 模块上下文结构定义

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;

** 模块的定义

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

};

* 实现handler的挂载函数。（按处理阶段挂载/按需挂载）

** handler模块挂载

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;

}

* 编写handler处理函数。模块的功能主要通过这个函数完成。

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);
}

参考： http://tengine.taobao.org/book/chapter_03.html