Add --proxy option

main.go

@@ -21,6 +21,7 @@ import (
 	"html/template"
 	"log"
 	"net/http"
+	"net/url"
 	"path"
 
 	"github.com/gorilla/mux"
@@ -31,8 +32,20 @@ func main() {
 	bind := pflag.StringP("bind", "b", ":5000", "Address to bind the server to, [addr]:port")
 	templateDir := pflag.String("template-dir", "./templates", "Templates directory")
 	staticDir := pflag.String("static-dir", "./static", "Static files directory")
+	proxy := pflag.String("proxy", "", "Proxy URL, with no scheme http is assumed")
 	pflag.Parse()
 
+	var proxyUrl *url.URL
+	if *proxy != "" {
+		u, err := url.Parse(*proxy)
+
+		if err != nil {
+			log.Fatalln("Invalid proxy URL:", err)
+		}
+
+		proxyUrl = u
+	}
+
 	tmpl := template.Must(template.ParseGlob(path.Join(*templateDir, "*.html")))
 
 	r := mux.NewRouter()
@@ -47,7 +60,7 @@ func main() {
 		to := req.FormValue("to")
 		text := req.FormValue("text")
 
-		translation, err := Translate(from, to, text)
+		translation, err := Translate(from, to, text, proxyUrl)
 		if err != nil {
 			writeError(w, 500, err)
 		}
@@ -79,7 +92,7 @@ func main() {
 			return
 		}
 
-		translation, err := Translate(from, to, text)
+		translation, err := Translate(from, to, text, proxyUrl)
 		if err != nil {
 			writeError(w, 500, err)
 		}

translate.go

@@ -10,8 +10,21 @@ import (
 	"golang.org/x/net/html"
 )
 
+func getWithProxy(url string, proxy *url.URL) (*http.Response, error) {
+	client := &http.Client{}
+
+	if proxy != nil {
+		tr := &http.Transport{ Proxy: http.ProxyURL(proxy) }
+		client.Transport = tr
+	}
+
+	resp, err := client.Get(url)
+
+	return resp, err
+}
+
 // Requests and parses translation from Google
-func Translate(fromLang, toLang, text string) (string, error) {
+func Translate(fromLang, toLang, text string, proxy *url.URL) (string, error) {
 	// Escape parameters before embedding in URL
 	fromLang = url.QueryEscape(fromLang)
 	toLang = url.QueryEscape(toLang)
@@ -19,7 +32,7 @@ func Translate(fromLang, toLang, text string) (string, error) {
 
 	url := fmt.Sprintf("https://translate.google.com/m?sl=%s&tl=%s&q=%s", fromLang, toLang, text)
 
-	resp, err := http.Get(url)
+	resp, err := getWithProxy(url, proxy)
 	if err != nil {
 		return "", fmt.Errorf("Request failed: %v", err)
 	}