server/prpc: updated server according to protocol

server/prpc/decoding.go

Index: server/prpc/decoding.go
diff --git a/server/prpc/decoding.go b/server/prpc/decoding.go
index 874c48111b51c9267d89e6f4e071dadad013fb61..8379e223b31a2f5a8ef25fbbf3b630141896ea19 100644
--- a/server/prpc/decoding.go
+++ b/server/prpc/decoding.go
@@ -64,9 +64,9 @@ func requestFormat(contentType string) (format, error) {
 
 // readMessage decodes a protobuf message from an HTTP request.
 // Does not close the request body.
-func readMessage(r *http.Request, msg proto.Message) *httpError {
+func readMessage(r *http.Request, msg proto.Message) *protocolError {
 	if msg == nil {
-		panicf("cannot decode to nil")
+		panic("cannot decode to nil")
 	}
 	format, err := requestFormat(r.Header.Get(headerContentType))
 	if err != nil {
@@ -96,7 +96,7 @@ func readMessage(r *http.Request, msg proto.Message) *httpError {
 		err = proto.UnmarshalText(string(buf), msg)
 
 	default:
-		panicf("cannot happen")
+		panic("cannot happen")

[dnj, 2016/01/26 19:26:38]

nit: I'd prefer that you either don't check this case (b/c it can't happen) or
return a protocol error here instead of panic. I understand that this can never
happen, but having a panic inline with user request handling is a bad practice
in general.

 	}
 	if err != nil {
 		return errorf(http.StatusBadRequest, "could not decode body: %s", err)