在前面已經(jīng)看到了這個(gè) hello handler module 的部分重要的結(jié)構(gòu)。該模塊提供了 2 個(gè)配置指令，僅可以出現(xiàn)在 location 指令的作用域中。這兩個(gè)指令是 hello_string, 該指令接受一個(gè)參數(shù)來(lái)設(shè)置顯示的字符串。如果沒(méi)有跟參數(shù)，那么就使用默認(rèn)的字符串作為響應(yīng)字符串。
另一個(gè)指令是 hello_counter，如果設(shè)置為 on，則會(huì)在響應(yīng)的字符串后面追加 Visited Times:的字樣，以統(tǒng)計(jì)請(qǐng)求的次數(shù)。
這里有兩點(diǎn)注意一下：
下面來(lái)完整的給出 ngx_http_hello_module 模塊的完整代碼。
#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;
}通過(guò)上面一些介紹，我相信大家都能對(duì)整個(gè)示例模塊有一個(gè)比較好的理解。唯一可能感覺(jué)有些理解困難的地方在于ngx_http_hello_handler 函數(shù)里面產(chǎn)生和設(shè)置輸出。但其實(shí)大家在本書的前面的相關(guān)章節(jié)都可以看到對(duì) ngx_buf_t 和 request 等相關(guān)數(shù)據(jù)結(jié)構(gòu)的說(shuō)明。如果仔細(xì)看了這些地方的說(shuō)明的話，應(yīng)該對(duì)這里代碼的實(shí)現(xiàn)就比較容易理解了。因此，這里不再贅述解釋。
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