HTTP proxy written in Go to replace Tinyproxy (#269)

internal/httpproxy/http.go

@@ -0,0 +1,74 @@
+package httpproxy
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strings"
+)
+
+func (h *handler) handleHTTP(responseWriter http.ResponseWriter, request *http.Request) {
+	switch request.URL.Scheme {
+	case "http", "https":
+	default:
+		h.logger.Warn("Unsupported scheme %q", request.URL.Scheme)
+		http.Error(responseWriter, "unsupported scheme", http.StatusBadRequest)
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(h.ctx, h.relayTimeout)
+	defer cancel()
+	request = request.WithContext(ctx)
+
+	request.RequestURI = ""
+
+	for _, key := range hopHeaders {
+		request.Header.Del(key)
+	}
+
+	if !h.stealth {
+		setForwardedHeaders(request)
+	}
+
+	response, err := h.client.Do(request)
+	if err != nil {
+		http.Error(responseWriter, "server error", http.StatusInternalServerError)
+		h.logger.Warn("cannot request %s for client %q: %s",
+			request.URL, request.RemoteAddr, err)
+		return
+	}
+	defer response.Body.Close()
+	if h.verbose {
+		h.logger.Info("%s %s %s %s", request.RemoteAddr, response.Status, request.Method, request.URL)
+	}
+
+	for _, key := range hopHeaders {
+		response.Header.Del(key)
+	}
+
+	targetHeaderPtr := responseWriter.Header()
+	for key, values := range response.Header {
+		for _, value := range values {
+			targetHeaderPtr.Add(key, value)
+		}
+	}
+
+	responseWriter.WriteHeader(response.StatusCode)
+	if _, err := io.Copy(responseWriter, response.Body); err != nil {
+		h.logger.Error("%s %s: body copy error: %s", request.RemoteAddr, request.URL, err)
+	}
+}
+
+func setForwardedHeaders(request *http.Request) {
+	clientIP, _, err := net.SplitHostPort(request.RemoteAddr)
+	if err != nil {
+		return
+	}
+	// keep existing proxy headers
+	if prior, ok := request.Header["X-Forwarded-For"]; ok {
+		clientIP = fmt.Sprintf("%s,%s", strings.Join(prior, ", "), clientIP)
+	}
+	request.Header.Set("X-Forwarded-For", clientIP)
+}