Merge pull request #86 from lbryio/cors

Cors

extras/api/server.go

@@ -17,6 +17,12 @@ import (
 // ResponseHeaders are returned with each response
 var ResponseHeaders map[string]string
 
+// CorsDomains Allowed domains for CORS Policy
+var CorsDomains []string
+
+// CorsAllowLocalhost if true localhost connections are always allowed
+var CorsAllowLocalhost bool
+
 // Log allows logging of events and errors
 var Log = func(*http.Request, *Response, error) {}
 
@@ -77,6 +83,32 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set(key, value)
 		}
 	}
+	origin := r.Header.Get("origin")
+	for _, d := range CorsDomains {
+		if d == origin {
+			w.Header().Set("Access-Control-Allow-Origin", d)
+			vary := w.Header().Get("Vary")
+			if vary != "*" {
+				if vary != "" {
+					vary += ", "
+				}
+				vary += "Origin"
+			}
+			w.Header().Set("Vary", vary)
+		}
+	}
+
+	if CorsAllowLocalhost && strings.HasPrefix(origin, "http://localhost:") {
+		w.Header().Set("Access-Control-Allow-Origin", origin)
+		vary := w.Header().Get("Vary")
+		if vary != "*" {
+			if vary != "" {
+				vary += ", "
+			}
+			vary += "Origin"
+		}
+		w.Header().Set("Vary", vary)
+	}
 
 	// Stop here if its a preflighted OPTIONS request
 	if r.Method == "OPTIONS" {