add missing http01proxy file

internal/http01proxy/proxy.go

@@ -0,0 +1,83 @@
+package http01proxy
+
+import (
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// ListenAndServe will start the HTTP-01 proxy
+func ListenAndServe(target string, timeout time.Duration) error {
+	target = strings.TrimSuffix(target, "/")
+
+	// TODO accept listener?
+	targetURL, err := url.Parse(target)
+	if nil != err {
+		panic(err)
+	}
+
+	//proxyHandler := httputil.NewSingleHostReverseProxy(targetURL)
+	proxyHandler := &httputil.ReverseProxy{
+		Director: func(req *http.Request) {
+			req.Header.Del("X-Forwarded-For")
+			req.Header.Del("X-Forwarded-Proto")
+			req.Header.Del("X-Forwarded-Port")
+
+			targetQuery := targetURL.RawQuery
+			req.URL.Scheme = targetURL.Scheme
+			req.URL.Host = targetURL.Host
+			req.Host = targetURL.Host
+			//req.Header.Set("Host", targetURL.Host)
+			req.URL.Path, req.URL.RawPath = joinURLPath(targetURL, req.URL)
+
+			if targetQuery == "" || req.URL.RawQuery == "" {
+				req.URL.RawQuery = targetQuery + req.URL.RawQuery
+			} else {
+				req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
+			}
+
+			if _, ok := req.Header["User-Agent"]; !ok {
+				// explicitly disable User-Agent so it's not set to default value
+				req.Header.Set("User-Agent", "")
+			}
+		},
+	}
+
+	return http.ListenAndServe(":80", proxyHandler)
+}
+
+// Taken from https://golang.org/src/net/http/httputil/reverseproxy.go
+func joinURLPath(a, b *url.URL) (path, rawpath string) {
+	if a.RawPath == "" && b.RawPath == "" {
+		return singleJoiningSlash(a.Path, b.Path), ""
+	}
+	// Same as singleJoiningSlash, but uses EscapedPath to determine
+	// whether a slash should be added
+	apath := a.EscapedPath()
+	bpath := b.EscapedPath()
+
+	aslash := strings.HasSuffix(apath, "/")
+	bslash := strings.HasPrefix(bpath, "/")
+
+	switch {
+	case aslash && bslash:
+		return a.Path + b.Path[1:], apath + bpath[1:]
+	case !aslash && !bslash:
+		return a.Path + "/" + b.Path, apath + "/" + bpath
+	}
+	return a.Path + b.Path, apath + bpath
+}
+
+func singleJoiningSlash(a, b string) string {
+	aslash := strings.HasSuffix(a, "/")
+	bslash := strings.HasPrefix(b, "/")
+	switch {
+	case aslash && bslash:
+		return a + b[1:]
+	case !aslash && !bslash:
+		return a + "/" + b
+	}
+	return a + b
+}