Nginx的return关键字属于HttpRewriteModule模块:
语法:return http状态码
默认值:无
上下文:server,location,if
该指令将结束执行直接返回http状态码到客户端.
支持的http状态码:200, 204, 400, 402-406, 408, 410, 411, 413, 416 , 500-504，还有非标准的444状态码.
使用方法:
#不符合规则的返回403禁止访问
location /download/ {
rewrite ^(/download/.*)/media/(.*)\..*$ $1/mp3/$2.mp3 break;
return 403;
}
小技巧
这些小技巧都是wiki里没有介绍的，而系统却是支持的。
如下配置文件:
server {
server_name test.liguangming.com;
listen 80;
location / {
add_header Content-Type "text/plain;charset=utf-8";
return 200 "Your IP Address:$remote_addr";
}
}
执行请求:
curl -i http://test.liguangming.com
返回内容如下:
HTTP/1.1 200 OK
Server: nginx/1.0.13
Date: Thu, 10 May 2012 10:01:15 GMT
Content-Type: application/octet-stream
Content-Length: 30
Connection: keep-alive
Content-Type: text/plain;charset=utf-8
Your IP Address:123.128.217.19
好玩吧,还有呢，比如如下的配置文件:
server {
server_name test.liguangming.com;
listen 80;
location / {
return http://liguangming.com/;
}
}
执行请求:
curl -i http://test.liguangming.com
返回内容如下:
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.0.13
Date: Thu, 10 May 2012 10:06:58 GMT
Content-Type: text/html
Content-Length: 161
Connection: keep-alive
Location: http://liguangming.com/
Content-Type: text/plain;charset=utf-8
<html>
<head><title>302 Found</title></head>
<body bgcolor="white">
<center><h1>302 Found</h1></center>
<hr><center>nginx/1.0.13</center>
</body>
</html>
是个302转向，为什么会这样呢？在nginx的源代码里找到src/http/modules/ngx_http_rewrite_module.c文件, 找到return关键字的解析配置:
{ ngx_string("return"),
NGX_HTTP_SRV_CONF|NGX_HTTP_SIF_CONF|NGX_HTTP_LOC_CONF|NGX_HTTP_LIF_CONF
|NGX_CONF_TAKE12,
ngx_http_rewrite_return,
NGX_HTTP_LOC_CONF_OFFSET,
0,
NULL },
看到NGX_CONF_TAKE12,原来return允许接受一个或者两个参数啊.
再接着往下看找到ngx_http_rewrite_return函数:
static char *
ngx_http_rewrite_return(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
ngx_http_rewrite_loc_conf_t *lcf = conf;
u_char *p;
ngx_str_t *value, *v;
ngx_http_script_return_code_t *ret;
ngx_http_compile_complex_value_t ccv;
ret = ngx_http_script_start_code(cf->pool, &lcf->codes,
sizeof(ngx_http_script_return_code_t));
if (ret == NULL) {
return NGX_CONF_ERROR;
}
value = cf->args->elts;
ngx_memzero(ret, sizeof(ngx_http_script_return_code_t));
ret->code = ngx_http_script_return_code;
p = value[1].data;
ret->status = ngx_atoi(p, value[1].len);
if (ret->status == (uintptr_t) NGX_ERROR) {
if (cf->args->nelts == 2
&& (ngx_strncmp(p, "http://", sizeof("http://") - 1) == 0
|| ngx_strncmp(p, "https://", sizeof("https://") - 1) == 0
|| ngx_strncmp(p, "$scheme", sizeof("$scheme") - 1) == 0))
{
ret->status = NGX_HTTP_MOVED_TEMPORARILY;
v = &value[1];
} else {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"invalid return code \"%V\"", &value[1]);
return NGX_CONF_ERROR;
}
} else {
if (cf->args->nelts == 2) {
return NGX_CONF_OK;
}
v = &value[2];
}
ngx_memzero(&ccv, sizeof(ngx_http_compile_complex_value_t));
ccv.cf = cf;
ccv.value = v;
ccv.complex_value = &ret->text;
if (ngx_http_compile_complex_value(&ccv) != NGX_OK) {
return NGX_CONF_ERROR;
}
return NGX_CONF_OK;
}
当一个参数的时候，并不一定要是状态码，如果是一个网址，以http，https,或者与请求相同的协议，就会返回一个302重定向. 相当于:
return 302 http://liguangming.com/;
第二个参数会作为内容返回,其实这不就是一个简单的原生的echo模块吗? 赶着回去吃饭，匆忙写成的，难免有疏漏，有时间再修改.
参考资源
May-10 18:32 
