nginx 逻辑判断if语句使用

当nginx 需要多重过滤转发时，我们会用到逻辑判断if，下面是栗子：

upstream xx-12 {server ip:8080;
}
server {listen 8080 ssl;ssl_certificate /etc/nginx/conf.d/cert.pem;ssl_certificate_key /etc/nginx/conf.d/key.pem;ssl_prefer_server_ciphers  on;ssl_session_cache shared:SSL:1m;ssl_session_timeout 5m;client_max_body_size 50M;server_name _;location / {gzip on;gzip_min_length 1k;gzip_buffers 4 16k;gzip_comp_level 2;gzip_types text/plain application/x-javascript text/css application/xml                 text/javascript application/x-httpd-php image/jpeg image/gif image/png;gzip_vary off;gzip_disable "MSIE [1-6]\\.";proxy_connect_timeout 30m;proxy_send_timeout 1d;proxy_read_timeout 1d;proxy_pass https://xx-12;proxy_redirect off;proxy_http_version 1.1;proxy_set_header Upgrade $http_upgrade;proxy_set_header Connection "upgrade";if ($http_referer ~* "ip:8080/sm"){proxy_pass http://xx-12;break;} }
}

if 语句可以过滤下一级路径，从而转发到实际的资源地址。