Fetcher

Provides an interface for network IO abstraction.

class FetcherInterface

Defines an interface for abstract network download.

By providing a concrete implementation of the abstract interface, users of the framework can plug-in their preferred/customized network stack.

download_bytes(url, max_length)

Download bytes from given url

Returns the downloaded bytes, otherwise like download_file()

Parameters

• url (str) –

• max_length (int) –

Return type

bytes

download_file(url, max_length)

Opens a connection to ‘url’ and downloads the content up to ‘max_length’.

Parameters

• url (str) – a URL string that represents the location of the file.

• max_length (int) – an integer value representing the length of the file or an upper bound.

Raises

DownloadLengthMismatchError – downloaded bytes exceed ‘max_length’.

Yields

A TemporaryFile object that points to the contents of ‘url’.

Return type

Iterator[IO]

abstract fetch(url)

Fetches the contents of HTTP/HTTPS url from a remote server.

Parameters

url (str) – A URL string that represents a file location.

Raises

• tuf.exceptions.SlowRetrievalError – A timeout occurs while receiving data.

• tuf.exceptions.FetcherHTTPError – An HTTP error code is received.

Returns

A bytes iterator

Return type

Iterator[bytes]