From 9e110380b9da31a40d7075a92176f99bbc641990 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Sun, 23 Apr 2023 22:42:08 -0500
Subject: modularize proxying

---
 main.go | 134 +++++++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 87 insertions(+), 47 deletions(-)

diff --git a/main.go b/main.go
index bd85dcc..3516374 100644
--- a/main.go
+++ b/main.go
@@ -11,62 +11,102 @@ import (
 )
 
 
-//type Endpoint struct {
-//	path string
-//	address string
-//}
-//
-//
-//func proxy(w http.ResponseWriter, req *http.Request, end Endpoint) {
-//}
-//
-//func makeProxiedRequest(w http.ResponseWriter, req *http.Request, end Endpoint) {
-//	
-//}
-//
-
 func main() {
 	const addr = "localhost:3333"
+
 	log.Info("configuring reverse proxy...")
-	origin, err := url.Parse("http://localhost:8000")
+	configureEndpoint("/proxy1", "http://localhost:8000")
+
+	log.Infof("serving on %v", addr)
+	log.Fatal(http.ListenAndServe(addr, nil))
+}
+
+
+type Endpoint struct {
+	Path string
+	Origin *url.URL
+}
+
+
+func configureEndpoint(path, address string) {
+	log.Infof("proxying endpoint %v to %v", path, address)
+	origin, err := url.Parse(address)
 	if err != nil {
 		log.Fatal(err)
 	}
-	log.Infof("listening on %v", addr)
-	http.ListenAndServe(addr, http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
-		req.Host = origin.Host
-		req.URL.Host = origin.Host
-		req.URL.Scheme = origin.Scheme
-		req.RequestURI = ""
-		// set X-Forwarded-For
-		forwardedFor, _, _ := net.SplitHostPort(req.RemoteAddr)
-		req.Header.Set("X-Forwarded-For", forwardedFor)
-		response, err := http.DefaultClient.Do(req)
-		if err != nil {
-			w.WriteHeader(http.StatusInternalServerError)
-			fmt.Fprintf(w, "%v", err)
-			log.Fatal(err)
-		}
 
-		// copy header
-		for key, values := range response.Header {
-			for _, value := range values {
-				w.Header().Add(key, value)
-			}
-		}
+	end := Endpoint{
+		Path: path,
+		Origin: origin,
+	}
 
-		// get trailer keys
-		trailerKeys := []string{}
-		for key := range response.Trailer {
-			trailerKeys = append(trailerKeys, key)
-		}
-		if (len(trailerKeys) > 0) {
-			w.Header().Set("Trailer", strings.Join(trailerKeys, ","))
+	http.HandleFunc(path + "/", func(w http.ResponseWriter, req *http.Request) {
+		log.Infof("REQ: %v", req.URL.Path)
+		proxy(w, req, end)
+	})
+}
+
+
+func proxy(w http.ResponseWriter, req *http.Request, end Endpoint) {
+	response := proxyRequest(w, req, end)
+	proxyResponse(w, response)
+}
+
+
+func proxyRequest(w http.ResponseWriter, req *http.Request, end Endpoint)  *http.Response {
+	// configure host address
+	req.Host = end.Origin.Host
+	req.URL.Host = end.Origin.Host
+
+	// strip proxy endpoint path from request path
+	req.URL.Path = strings.TrimPrefix(req.URL.Path, end.Path)
+
+	// set X-Forwarded-For
+	forwardedFor, _, _ := net.SplitHostPort(req.RemoteAddr)
+	req.Header.Set("X-Forwarded-For", forwardedFor)
+
+	// misc request cleanups
+	req.URL.Scheme = end.Origin.Scheme
+	req.RequestURI = ""
+	
+	// make request
+	response, err := http.DefaultClient.Do(req)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprintf(w, "%v", err)
+		log.Fatal(err)
+	}
+
+	return response
+}
+
+
+func proxyResponse(w http.ResponseWriter, response *http.Response) {
+	// copy header
+	for key, values := range response.Header {
+		for _, value := range values {
+			w.Header().Add(key, value)
 		}
+	}
 
-		w.WriteHeader(response.StatusCode)
+	// get trailer keys
+	trailerKeys := []string{}
+	for key := range response.Trailer {
+		trailerKeys = append(trailerKeys, key)
+	}
+	if (len(trailerKeys) > 0) {
+		w.Header().Set("Trailer", strings.Join(trailerKeys, ","))
+	}
 
-		// copy body
-		io.Copy(w, response.Body)
-	}))
+	w.WriteHeader(response.StatusCode)
+
+	// copy body to client
+	io.Copy(w, response.Body)
+
+	// write trailers
+	for key, values := range response.Trailer {
+		for _, value := range values {
+			w.Header().Set(key, value)
+		}
+	}
 }
-- 
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