Create subpackage handlers, refactor getRootURL

handlers/handlers.go

@@ -0,0 +1,44 @@
+package handlers
+
+import (
+	"fmt"
+	"net/http"
+)
+
+// RootURL returns the root URL of the HTTP request. Optionally, a domain and a
+// base path may be provided which will be used to construct the root URL if
+// they are not empty. Otherwise the hostname will be determined from the
+// request and the path will be empty.
+func RootURL(r *http.Request, domain, path string) string {
+	host := r.Host
+	if len(domain) > 0 {
+		host = domain
+	}
+
+	root := fmt.Sprintf("%s://%s", Scheme(r), host)
+	if len(path) > 0 {
+		root = fmt.Sprintf("%s/%s", root, path)
+	}
+
+	return root
+}
+
+// Scheme returns the underlying URL scheme of the original request.
+func Scheme(r *http.Request) string {
+	if r.TLS != nil {
+		return "https"
+	}
+	if scheme := r.Header.Get("X-Forwarded-Proto"); scheme != "" {
+		return scheme
+	}
+	if scheme := r.Header.Get("X-Forwarded-Protocol"); scheme != "" {
+		return scheme
+	}
+	if ssl := r.Header.Get("X-Forwarded-Ssl"); ssl == "on" {
+		return "https"
+	}
+	if scheme := r.Header.Get("X-Url-Scheme"); scheme != "" {
+		return scheme
+	}
+	return "http"
+}

main.go

@@ -24,6 +24,8 @@ import (
 	_ "github.com/mattn/go-sqlite3"
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+
+	"github.com/consbio/mbtileserver/handlers"
 )
 
 type ServiceInfo struct {
@@ -336,18 +338,10 @@ func getServiceOr404(c echo.Context) (string, error) {
 	return id, nil
 }
 
+// getRootURL is a convenience function to determine the root URL from the
+// echo.Context.
 func getRootURL(c echo.Context) string {
-	host := c.Request().Host
-	if len(domain) > 0 {
-		host = domain
-	}
-
-	root := fmt.Sprintf("%s://%s", c.Scheme(), host)
-	if len(path) > 0 {
-		root = fmt.Sprintf("%s/%s", root, path)
-	}
-
-	return root
+	return handlers.RootURL(c.Request(), domain, path)
 }
 
 func ListServices(c echo.Context) error {