proxy of flickr images to workaround the CORS issue on images (can't draw them on canvas / webgl)

proxy_flickr.go

package main

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func main() {
  http.HandleFunc("/", GetImageFromFlickr)
  fmt.Println("Up and listening on port 9999")
  http.ListenAndServe(":9999", nil)
}

func GetImageFromFlickr(rw http.ResponseWriter, request *http.Request) {
  farm := request.FormValue("farm")
  server := request.FormValue("server")
  id := request.FormValue("id")
  secret := request.FormValue("secret")

  if farm == "" || server == "" || id == "" || secret == "" {
    rw.WriteHeader(400)
  } else {
    url := fmt.Sprintf("http://farm%s.static.flickr.com/%s/%s_%s_z.jpg", farm, server, id, secret)
    response, err := http.Get(url)
    if err != nil {
        fmt.Fprintf(rw, "Error fetching the image")
    }
    defer response.Body.Close()
    body, err := ioutil.ReadAll(response.Body)
    if err != nil {
        fmt.Fprintf(rw, "Error while reading the body of the response; %s", err)
    }
    rw.Header().Set("Access-Control-Allow-Origin", "*")
    _, err = rw.Write(body)
    if err != nil {
        panic("Couldn't write the response. Exiting.")
    }
  }
}

proxy_flickr.js

var http = require("http");
var request = require("request");
var URL = require("url");
http.createServer(function (req, res) {
  var url = URL.parse(req.url, true);
  var farm = url.query.farm;
  var server = url.query.server;
  var id = url.query.id;
  var secret = url.query.secret;
  if (url && farm && server && id && secret) {
    var src = "http://farm"+farm+".static.flickr.com/"+server+"/"+id+"_"+secret+"_z.jpg";
    res.setHeader("access-control-allow-origin", "*");
    request.get(src).pipe(res);
  }
  else {
    res.statusCode = 404;
    res.end();
  }
}).listen(9999);

proxy_flickr.md

example with rx-dom

var querystring = require("querystring");
var Rx = require("rx-dom");
var API_KEY = "???";
var PROXY_SERVER = "http://localhost:9999";

function photoUrl (photo) {
  return PROXY_SERVER+"/?"+querystring.stringify({
    farm: photo.farm,
    server: photo.server,
    id: photo.id,
    secret: photo.secret
  });
}
function searchPhotosFlickrURL (nb, text) {
  return "https://www.flickr.com/services/rest/?"+querystring.stringify({
    jsoncallback: "JSONPCallback",
    method: "flickr.photos.search",
    text: text,
    per_page: nb,
    format: "json",
    api_key: API_KEY
  });
}
function fetchPhotos (nb) {
  return Rx.DOM.jsonpRequest(searchPhotosFlickrURL(nb, "Landscape"))
  .map(function (json) {
    return json.response.photos.photo.map(photoUrl);
  });
}