backend_tips.md

...menustart

• Backend tips
  • CORS
    • test whether your server supoort CORS
  • check whether server enable 'keepalive' feature
  • self signed cert
  • Redeem
  • golang forward request

...menuend

Backend tips

CORS

test whether your server supoort CORS

• in chrome console

var xhr = new XMLHttpRequest();
xhr.open('OPTIONS', 'http://localhost:3000',true);
xhr.send();

var xhr = new XMLHttpRequest();
xhr.open('POST', 'http://localhost:3000/setuserdata/test-UUID-0',true);
xhr.setRequestHeader("auth-ts", 12234 )
xhr.setRequestHeader("auth-sig", 12234 )
xhr.send();

check whether server enable 'keepalive' feature

curl  -Iv  -k  <url> <url>  2>&1 | grep -i '#0'

• if server enable 'keepalive' , it should output something like

* Re-using existing connection! (#0) with proxy 127.0.0.1

self signed cert

# copy and run in you terminal

case `uname -s` in
    (Linux*)     sslConfig=/etc/ssl/openssl.cnf;;
    (Darwin*)    sslConfig=/System/Library/OpenSSL/openssl.cnf;;
esac

ipaddr=`ifconfig | grep -Eo 'inet (addr:)?([0-9]*\.){3}[0-9]*' | grep -Eo '([0-9]*\.){3}[0-9]*' | grep -v '127.0.0.1'`

openssl req \
    -newkey rsa:2048 \
    -x509 \
    -nodes \
    -keyout server.key \
    -new \
    -out server.pem \
    -subj /CN=$ipaddr \
    -reqexts SAN \
    -extensions SAN \
    -config <(cat $sslConfig \
        <(printf '[SAN]\nsubjectAltName=DNS:localhost')) \
    -sha256 \
    -days 3650

Trust it in KeyChain Access, this cert is named your ipi

More simplier:

go run $GOROOT/src/crypto/tls/generate_cert.go --host golangtc.com

for homebrew go, replace GOROOT is /usr/local/opt/go/libexec

Redeem

redeem

golang forward request

// Serve a reverse proxy for a given url
func serveReverseProxy(target string, res http.ResponseWriter, req *http.Request) {
    // parse the url
    url, _ := url.Parse(target)

    // create the reverse proxy
    proxy := httputil.NewSingleHostReverseProxy(url)

    // Update the headers to allow for SSL redirection
    req.URL.Host = url.Host
    req.URL.Scheme = url.Scheme
    req.Header.Set("X-Forwarded-Host", req.Header.Get("Host"))
    req.Host = url.Host

    // Note that ServeHttp is non blocking and uses a go routine under the hood
    proxy.ServeHTTP(res, req)
}