license_check.py

#!/usr/bin/env python

# Copyright 2023 Specter Ops, Inc.
#
# Licensed under the Apache License, Version 2.0
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# SPDX-License-Identifier: Apache-2.0

# About this file:
#
# license_check.py is a naive attempt at automatically auditing and inserting copyright headers
# for the chosen license. It will attempt to match the license header and identify if the header
# has been damaged.
#
# Review of changed files is a must before committing after running this file.
#

import os
import pathlib
import re

from datetime import datetime
from typing import List

# Source root files for license information
ROOT_LICENSE_FILE = "LICENSE"
ROOT_LICENSE_HEADER_FILE = "LICENSE.header"

# Apache License 2.0 copy
LICENSE = """                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

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      the copyright owner that is granting the License.

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      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
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   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
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   Copyright [yyyy] [name of copyright owner]

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
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"""

# Apache License 2.0 header copy
LICENSE_HEADER = """Copyright {year} Specter Ops, Inc.

Licensed under the Apache License, Version 2.0
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

SPDX-License-Identifier: Apache-2.0""".format(
    year=str(datetime.now().year)
)

# XML requires a block quote, so it's easier to just hand format it here
XML_LICENSE_HEADER = "<!--\n" + LICENSE_HEADER + "\n-->"

# Any path that contains one of these elements will be ignored when performing license checking. Eventually would
# like to have this also extend to the .gitignore file.
IGNORED_PATH_ELEMENTS = [
    "node_modules",
    "dist",
    ".beagle",
    ".yarn",
    "cmd/api/src/api/static/assets",
    # This is generated code that we don't really care about
    "packages/go/cypher/parser",
    # These are vendored packages
    "packages/python/beagle/beagle/semver",
    "cmd/api/src/cmd/testidp/samlidp",
    # Ignore checksums
    "sha256",
    # Ignore this file
    "license_check.py",
]

# Any file extension found below will be ignored when performing license checking.
IGNORED_EXTENSIONS = [
    ".iml",
    ".zip",
    ".g4",
    ".sum",
    ".bazel",
    ".bzl",
    ".typed",
    ".md",
    ".json",
    ".template",
    "sha256",
    ".pyc",
    ".gif",
    ".tiff",
    ".lock",
    ".txt",
    ".png",
    ".jpg",
    ".jpeg",
    ".ico",
    ".gz",
    ".tar",
    ".woff2",
    ".header",
    ".pro",
    ".cert",
    ".crt",
    ".key",
    ".example",
    ".svg",
]

# Any file listed below is included regardless of exclusions.
MUST_CHECK_PATHS = [".yarn/plugins/nested-workspace/plugin-nested-workspace.js"]


def is_path_ignored(path: str) -> bool:
    return any([ignored_elem in path for ignored_elem in IGNORED_PATH_ELEMENTS])


def generate_license_header(comment_prefix: str) -> str:
    golang_header: str = ""

    for line in LICENSE_HEADER.split("\n"):
        if line.strip() == "":
            golang_header += comment_prefix + "\n"
        else:
            golang_header += comment_prefix + " " + line + "\n"

    return golang_header


# Below is a map of file extension to a correctly commented and formatted license header.
LICENSE_HEADERS_BY_EXTENSION = {
    ".svg": XML_LICENSE_HEADER,
    ".xml": XML_LICENSE_HEADER,
    ".html": XML_LICENSE_HEADER,
    ".go": generate_license_header("//"),
    ".mod": generate_license_header("//"),
    ".work": generate_license_header("//"),
    ".tsx": generate_license_header("//"),
    ".ts": generate_license_header("//"),
    ".js": generate_license_header("//"),
    ".jsx": generate_license_header("//"),
    ".cjs": generate_license_header("//"),
    ".py": generate_license_header("#"),
    ".yaml": generate_license_header("#"),
    ".yml": generate_license_header("#"),
    ".sh": generate_license_header("#"),
    ".scss": generate_license_header("//"),
    ".Dockerfile": generate_license_header("#"),
    ".cue": generate_license_header("//"),
    ".sql": generate_license_header("--"),
    ".toml": generate_license_header("#"),
}

# Below is a list of valid file headers that the license must be placed after
FILE_HEADER_PREFIXES = [
    # POSIX exec header
    "#!",
    # XML header
    "<?xml",
]


def content_has_header(path: str, content_lines: List[str], header: str) -> bool:
    matching_header = False
    header_lines = header.splitlines()
    header_lineno = 0

    for line in content_lines:
        if line.strip() == header_lines[header_lineno].strip():
            # Mark that we're matching the header
            if not matching_header:
                matching_header = True

            # Advance the line being matched
            header_lineno += 1

            # Ignore this file, it has a valid license header
            if header_lineno >= len(header_lines):
                return True

        elif re.search("Copyright \d{4} Specter Ops, Inc.", line.strip()):
            matching_header = True
            header_lineno += 1

        elif matching_header:
            print(f"WARNING: Path {path} contains damaged license information.")
            return True

    return False


def _is_file_header(line: str) -> bool:
    for header in FILE_HEADER_PREFIXES:
        if line.startswith(header):
            return True
    return False


def insert_license_header(path: str, header: str) -> None:
    with open(path, "r") as fin:
        content = fin.read()

    # Split the content into lines
    content_lines = content.splitlines()

    # Check if there is no content or if the content already has a license header
    if content_has_header(path, content_lines, header):
        return

    # Try to find a script exec header to advance the line offset
    line_offset = 1 if len(content_lines) > 0 and _is_file_header(content_lines[0]) else 0

    for line in content_lines[line_offset:]:
        # Make sure to skip leading newlines since we'll add our own
        if line.strip() != "":
            break

        line_offset += 1

    # Output the file with the copy
    with open(path, "w") as fout:
        if line_offset > 0:
            # Write out the exec header first
            fout.write(content_lines[0])

            # Add a trailing newline to the header to separate it from the license
            fout.write("\n\n")

        # Write out the license header for the file
        fout.write(header)
        fout.write("\n")

        # Finish writing the content line by line starting at the exec header offset, if one exists
        for line in content_lines[line_offset:]:
            fout.write(line)
            fout.write("\n")


def validate_license_header(path: str, header: str):
    with open(path, "r") as fin:
        content = fin.read()

    if content.count("SPDX-License-Identifier: Apache-2.0") != 1:
        print(f"WARNING: License for {path} may be damaged.")


def check_file(path: pathlib.Path, path_str: str) -> None:
    license_header = LICENSE_HEADERS_BY_EXTENSION.get(path.suffix)

    if license_header is None:
        if path.suffix not in IGNORED_EXTENSIONS:
            print(f"No license header information for file extension: {path.suffix} {path}")
    else:
        insert_license_header(path_str, license_header)
        validate_license_header(path_str, license_header)


def main() -> None:
    if not os.path.isfile(ROOT_LICENSE_FILE):
        print(f"{ROOT_LICENSE_FILE} file is missing. Writing a new copy.")

        with open(ROOT_LICENSE_FILE, "w") as fout:
            fout.write(LICENSE)

    if not os.path.isfile(ROOT_LICENSE_HEADER_FILE):
        print(f"{ROOT_LICENSE_HEADER_FILE} file is missing. Writing a new copy.")

        with open(ROOT_LICENSE_HEADER_FILE, "w") as fout:
            fout.write(LICENSE_HEADER)

    # Walk the root first
    for root_path, _, filenames in os.walk("./"):
        for filename in filenames:
            path_str = os.path.join(root_path, filename)
            path = pathlib.Path(path_str)

            if path.suffix is None or path.suffix == "" or is_path_ignored(path_str):
                continue

            check_file(path, path_str)

    # Visit any files that may have been excluded but are marked as must check
    for path_str in MUST_CHECK_PATHS:
        check_file(pathlib.Path(path_str), path_str)


if __name__ == "__main__":
    main()