python-tuf/tuf/interposition

Examples

import tuf.interposition
# configuration is a JSON object in tuf.interposition.json
tuf.interposition.configure()

Option one

tuf.interposition.interpose()
# now you have TUF
url = 'http://example.com/path/to/document'
urllib.urlopen( url )
urllib.urlretrieve( url )
urllib2.urlopen( url )
tuf.interposition.go_away()
# now you do not have TUF

Option two

@tuf.interposition.open_url
def instancemethod( self, url, ... )

Configuration

Example of a configuration JSON object

{
    "configurations": {
        "seattle.cs.washington.edu": {
            "repository_directory": "client/",
            "repository_mirrors" : {
                "mirror1": {
                    "url_prefix": "http://seattle-tuf.cs.washington.edu",
                    "metadata_path": "metadata",
                    "targets_path": "targets",
                    "confined_target_dirs": [ "" ]
                }
            },
            ("target_paths": [
                { ".*/(simple/\\w+)/$": "{0}/index.html" },
                { ".*/(packages/.+)$": "{0}" }
            ],
            "ssl_certificates": "cacert.pem")
        }
    }
}

TODO: Explain network_locations, target_paths, and the rest of the parameters.

target_paths is optional: If you do not tell TUF to selectively match paths with regular expressions, TUF will work over any path under the given network location. However, if you do specify it, you are then telling TUF how to transform a specified path into another one, and TUF will not recognize any unspecified path for the given network location.

Unless any url_prefix begins with "https://", ssl_certificates is optional; it must specify certificates bundled as PEM (RFC 1422).

Limitations (at the time of writing)

• The entire urllib or urllib2 contract is not honoured.
• Downloads are not thread safe.
• Uses some Python features (e.g. string formatting) not available in earlier versions (e.g. < 2.6).
• Uses some Python features (e.g. urllib, urllib2, urlparse) not available in later versions (e.g. >= 3).