treewide: add license header and enable haslicense linter

Change-Id: I873a8d4082d75e8f813d8a726a41187eea7a065e
Reviewed-on: https://review.monogon.dev/c/monogon/+/3825
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/osbase/socksproxy/protocol.go b/osbase/socksproxy/protocol.go
index d920099..0d5d133 100644
--- a/osbase/socksproxy/protocol.go
+++ b/osbase/socksproxy/protocol.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package socksproxy
 
 import (
diff --git a/osbase/socksproxy/socksproxy.go b/osbase/socksproxy/socksproxy.go
index 2dd0c35..47a398c 100644
--- a/osbase/socksproxy/socksproxy.go
+++ b/osbase/socksproxy/socksproxy.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 // Package socksproxy implements a limited subset of the SOCKS 5 (RFC1928)
 // protocol in the form of a pluggable Proxy object. However, this
 // implementation is _not_ RFC1928 compliant, as it does not implement GSSAPI
diff --git a/osbase/socksproxy/socksproxy_test.go b/osbase/socksproxy/socksproxy_test.go
index 0132ab3..2c49ebd 100644
--- a/osbase/socksproxy/socksproxy_test.go
+++ b/osbase/socksproxy/socksproxy_test.go
@@ -1,3 +1,6 @@
+// Copyright The Monogon Project Authors.
+// SPDX-License-Identifier: Apache-2.0
+
 package socksproxy
 
 import (