Update project to have a somewhat working Signer proxy

cmd/hmacproxy/main.go

@@ -16,8 +16,8 @@ package main
 
 import (
 	"flag"
+	"net/http"
 	"net/http/httptest"
-	"net/url"
 	"os"
 
 	log "github.com/Sirupsen/logrus"
@@ -58,17 +58,11 @@ func main() {
 			proxyConfig.Signer.Key.Region,
 		}
 
-		signingDest, err := url.Parse("https://www.google.com")
+		signingProxy, err := hmacproxy.NewSigningProxy(signingCredential)
 		if err != nil {
 			log.Fatal(err)
 		}
-
-		signingProxy, err := hmacproxy.NewSigningProxy(signingDest, signingCredential)
-		if err != nil {
-			log.Fatal(err)
-		}
-		signingServer := httptest.NewServer(signingProxy)
-		defer signingServer.Close()
+		log.Fatal(http.ListenAndServe(proxyConfig.Signer.ListenerAddr, signingProxy))
 	}
 
 	if proxyConfig.Verifier != nil {

handlers.go

@@ -15,23 +15,35 @@
 package hmacproxy
 
 import (
+	"fmt"
 	"log"
 	"net/http"
 	"net/http/httputil"
 	"net/url"
 
 	"github.com/coreos-inc/hmacproxy/credential"
+	"github.com/elazarl/goproxy"
 )
 
-// NewSigningProxy instantiates a new signing proxy with the target url and the
-// statc credential specified.
-func NewSigningProxy(target *url.URL, cred credential.Credential) (*httputil.ReverseProxy, error) {
-	director := func(req *http.Request) {
-		log.Printf("Proxying request %v", req)
-		req.URL.Scheme = target.Scheme
-		req.URL.Host = target.Host
-	}
-	return &httputil.ReverseProxy{Director: director}, nil
+// NewSigningProxy instantiates a new signing proxy with the static credential specified.
+func NewSigningProxy(cred credential.Credential) (*goproxy.ProxyHttpServer, error) {
+	proxy := goproxy.NewProxyHttpServer()
+
+	proxy.OnRequest().DoFunc(
+		func(r *http.Request, ctx *goproxy.ProxyCtx) (*http.Request, *http.Response) {
+			if err := Sign4(r, cred); err != nil {
+				response := goproxy.NewResponse(
+					r,
+					goproxy.ContentTypeText,
+					http.StatusBadRequest,
+					fmt.Sprintf("Could not sign request: %v", err),
+				)
+				return r, response
+			}
+			return r, nil
+		})
+
+	return proxy, nil
 }
 
 // NewVerifyingProxy instantiates a new verifying proxy with the specified