proxy_http.go

package waygate

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

func proxyHttp(w http.ResponseWriter, r *http.Request, httpClient *http.Client, upstreamAddr string, behindProxy bool) {

	downstreamReqHeaders := r.Header.Clone()

	//upstreamAddr := fmt.Sprintf("%s:%d", address, port)
	upstreamUrl := fmt.Sprintf("http://%s%s", upstreamAddr, r.URL.RequestURI())

	fmt.Println(upstreamUrl)

	upstreamReq, err := http.NewRequest(r.Method, upstreamUrl, r.Body)
	if err != nil {
		errMessage := fmt.Sprintf("%s", err)
		w.WriteHeader(500)
		io.WriteString(w, errMessage)
		return
	}

	// ContentLength needs to be set manually because otherwise it is
	// stripped by golang. See:
	// https://golang.org/pkg/net/http/#Request.Write
	upstreamReq.ContentLength = r.ContentLength

	upstreamReq.Header = downstreamReqHeaders

	upstreamReq.Header["X-Forwarded-Host"] = []string{r.Host}

	remoteHost, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		errMessage := fmt.Sprintf("%s", err)
		w.WriteHeader(500)
		io.WriteString(w, errMessage)
		return
	}

	xForwardedFor := remoteHost

	if behindProxy {
		xForwardedFor := downstreamReqHeaders.Get("X-Forwarded-For")
		if xForwardedFor != "" {
			xForwardedFor = xForwardedFor + ", " + remoteHost
		}
	}

	upstreamReq.Header.Set("X-Forwarded-For", xForwardedFor)
	upstreamReq.Header.Set("Forwarded", fmt.Sprintf("for=%s", remoteHost))

	//upstreamReq.Host = fmt.Sprintf("%s:%d", tunnel.ClientAddress, tunnel.ClientPort)

	upstreamRes, err := httpClient.Do(upstreamReq)
	if err != nil {
		errMessage := fmt.Sprintf("%s", err)
		w.WriteHeader(502)
		io.WriteString(w, errMessage)
		return
	}
	defer upstreamRes.Body.Close()

	var forwardHeaders map[string][]string

	// TODO: do we need this?
	//if r.ProtoMajor > 1 {
	//	forwardHeaders = stripConnectionHeaders(upstreamRes.Header)
	//} else {
	//	forwardHeaders = upstreamRes.Header
	//}
	forwardHeaders = upstreamRes.Header

	downstreamResHeaders := w.Header()

	for k, v := range forwardHeaders {
		downstreamResHeaders[k] = v
	}

	w.WriteHeader(upstreamRes.StatusCode)
	io.Copy(w, upstreamRes.Body)
}

//// Need to strip out headers that shouldn't be forwarded from HTTP/1.1 to
//// HTTP/2. See https://tools.ietf.org/html/rfc7540#section-8.1.2.2
//var connectionHeaders = []string{
//	"Connection", "Keep-Alive", "Proxy-Connection", "Transfer-Encoding", "Upgrade",
//}
//
//func stripConnectionHeaders(headers map[string][]string) map[string][]string {
//	forwardHeaders := make(map[string][]string)
//
//	for k, v := range headers {
//		if stringInArray(k, connectionHeaders) {
//			continue
//		}
//
//		forwardHeaders[k] = v
//	}
//
//	return forwardHeaders
//}