support setting proxy to request exchange rates or map data

pkg/utils/http.go

@@ -0,0 +1,18 @@
+package utils
+
+import (
+	"net/http"
+	"net/url"
+)
+
+// SetProxyUrl sets proxy url to http transport according to specified proxy setting
+func SetProxyUrl(transport *http.Transport, proxy string) {
+	if proxy == "none" {
+		transport.Proxy = nil
+	} else if proxy != "system" {
+		proxy, _ := url.Parse(proxy)
+		transport.Proxy = http.ProxyURL(proxy)
+	} else {
+		transport.Proxy = http.ProxyFromEnvironment
+	}
+}