acme and redirection patch

+ Added experimental fix for redirection tailing problem
+ Added acme widget for first time users to setup https

src/mod/dynamicproxy/dpcore/utils.go

@@ -2,20 +2,45 @@ package dpcore
 
 import (
 	"net/url"
+	"strings"
 )
 
-func replaceLocationHost(urlString string, newHost string, useTLS bool) (string, error) {
+// replaceLocationHost rewrite the backend server's location header to a new URL based on the given proxy rules
+// If you have issues with tailing slash, you can try to fix them here (and remember to PR :D )
+func replaceLocationHost(urlString string, rrr *ResponseRewriteRuleSet, useTLS bool) (string, error) {
 	u, err := url.Parse(urlString)
 	if err != nil {
 		return "", err
 	}
 
+	//Update the schemetic if the proxying target is http
+	//but exposed as https to the internet via Zoraxy
 	if useTLS {
 		u.Scheme = "https"
 	} else {
 		u.Scheme = "http"
 	}
 
-	u.Host = newHost
+	u.Host = rrr.OriginalHost
+
+	if strings.Contains(rrr.ProxyDomain, "/") {
+		//The proxy domain itself seems contain subpath.
+		//Trim it off from Location header to prevent URL segment duplicate
+		//E.g. Proxy config: blog.example.com -> example.com/blog
+		//Location Header: /blog/post?id=1
+		//Expected Location Header send to client:
+		// blog.example.com/post?id=1 instead of blog.example.com/blog/post?id=1
+
+		ProxyDomainURL := "http://" + rrr.ProxyDomain
+		if rrr.UseTLS {
+			ProxyDomainURL = "https://" + rrr.ProxyDomain
+		}
+		ru, err := url.Parse(ProxyDomainURL)
+		if err == nil {
+			//Trim off the subpath
+			u.Path = strings.TrimPrefix(u.Path, ru.Path)
+		}
+	}
+
 	return u.String(), nil
 }