Add auth service protobuf

auth.proto

@@ -0,0 +1,31 @@
+syntax = "proto3";
+
+option go_package = "git.itzana.me/strafesnet/go-grpc/auth";
+
+package auth;
+
+service AuthService {
+  rpc GetSession(IdMessage) returns (SessionResponse);
+  rpc GetGroupRole(IdMessage) returns (RoleReponse);
+  rpc ValidateSession(IdMessage) returns (ValidateResponse);
+}
+
+message IdMessage {
+  string SessionID = 1;
+}
+
+message SessionResponse {
+  string SessionID = 1;
+  uint64 UserID = 2;
+  string Username = 3;
+  uint64 Created = 4;
+  uint64 Expires = 5;
+}
+
+message RoleReponse {
+  uint32 Role = 1;
+}
+
+message ValidateResponse {
+  bool Valid = 1;
+}