Using Google as HTTP Proxy (limited to GET)

proxy.go

package main

import (
    "bytes"
    "fmt"
    "github.com/elazarl/goproxy"
    "gopkg.in/h2non/filetype.v1"
    "log"
    "net/http"
)

func main() {
    proxy := goproxy.NewProxyHttpServer()
    proxy_url := "https://feedback.googleusercontent.com/gadgets/proxy?container=fbk&url=%s"

    proxy.OnRequest().DoFunc(
        func(r *http.Request, ctx *goproxy.ProxyCtx) (*http.Request, *http.Response) {
            proxy_req_url := fmt.Sprintf(proxy_url, r.URL.String())
            resp, _ := http.Get(proxy_req_url)

            bodyBuffer := new(bytes.Buffer)
            bodyBuffer.ReadFrom(resp.Body)
            body := bodyBuffer.String()

            kind, unknown := filetype.Match(bodyBuffer.Bytes())

            if unknown == nil {
                log.Printf("Unknown content type for URL: %s, using %s", r.URL.String(), kind.MIME.Value)
            }

            return r, goproxy.NewResponse(r,
                kind.MIME.Value, resp.StatusCode,
                body)
        })

    log.Fatal(http.ListenAndServe(":8080", proxy))
}