Change license of python programs importing scapy to gpl v2 (#665)

* Move optional steps for testing VMs out of README.md file
This may help avoid new users being confused that they must follow
those instructions.

Signed-off-by: Andy Fingerhut <[email protected]>

* Replace Apache-2.0 license on Python files that use Scapy to GPL-2.0-only
Also add doc/licenses.md file to list other Python packages that the
Python code in this repository depends upon, and why we believe their
licenses are compatible with this code being released as Apache-2.0.

Signed-off-by: Andy Fingerhut <[email protected]>

---------

Signed-off-by: Andy Fingerhut <[email protected]>
Signed-off-by: Andy Fingerhut <[email protected]>

Author: jafingerhut

doc/licenses.md

@@ -0,0 +1,58 @@
+# Introduction
+
+The P4 Consortium's strongly recommends that all source files in this
+repository be licensed with the Apache-2.0 license, and marked in a
+comment with the line:
+
+```
+# SPDX-License-Identifier: Apache-2.0
+```
+
+Exceptions to this are listed below.
+
+
+# Not an exception: Files that import packages released under the Apache-2.0 license
+
+That includes this list of Python packages:
+
++ grpc - https://pypi.org/project/grpc/
++ grpcio - https://pypi.org/project/grpcio/
++ p4.v1 - part of the P4Runtime API Python code, released under Apache-2.0
++ p4.config.v1 - part of the P4Runtime API Python code, released under
+  Apache-2.0
+
+
+# Not an exception: Files that import packages released under a BSD license
+
+That includes this list of Python packages:
+
++ mininet - https://github.com/mininet/mininet/blob/master/LICENSE
++ protobuf - https://pypi.org/project/protobuf/
+  + google.rpc package is auto-generated by Google protobuf
++ psutil - https://pypi.org/project/psutil/
+
+These are published under a BSD-3-Clause license.  As discussed here:
+
++ https://github.com/p4lang/p4c/blob/main/docs/licenses-apache-and-bsd.md
+
+we will publish such source files under the Apache-2.0 license, unless
+one of the exceptions below applies.
+
+
+# Exception: Files that import packages released under a GPL license
+
+That includes this list of Python packages:
+
++ scapy - https://pypi.org/project/scapy/
+
+As discussed here:
+
++ https://github.com/p4lang/p4c/blob/main/docs/licenses-apache-and-gpl-v2.md
+
+we recommend that any Python source files that import the scapy
+package, which is released under the GPL v2 license, also be licensed
+as GPL-2.0-only, with this comment line:
+
+```
+# SPDX-License-Identifier: GPL-2.0-only
+```

exercises/basic/receive.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 import os
 import sys
 

exercises/basic/send.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 import random
 import socket
 import sys

exercises/basic_tunnel/myTunnel_header.py

@@ -1,4 +1,5 @@
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 
 
 from scapy.all import *

exercises/basic_tunnel/receive.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 import os
 import sys
 

exercises/basic_tunnel/send.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 import argparse
 import random
 import socket

exercises/calc/calc.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 
 import re
 

exercises/ecn/receive.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 import sys
 
 from scapy.all import get_if_list, sniff

exercises/ecn/send.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 
 import socket
 import sys

exercises/link_monitor/probe_hdrs.py

@@ -1,4 +1,5 @@
-# SPDX-License-Identifier: Apache-2.0
+# SPDX-License-Identifier: GPL-2.0-only
+# Reason-GPL: import-scapy
 from scapy.all import *
 
 TYPE_PROBE = 0x812