host-replace 0.1.2

Replace host and domain names in text under various encoding schemes.

Host Replace

A Python package for replacing host and domain names in text under common encoding schemes.

Features

• Replace hostnames in text under common encodings (URL, HTML entity) while avoiding partial matches
• Replacements are encoded in the same way
• Supports UTF-8 string and byte inputs
• Supports unqualified hostnames and IPv4 addresses
• Partial support for case preservation

See sample.txt for detailed examples.

Installation

pip install hostreplace

Usage

CLI

usage: hostreplace [-h] [-o OUTPUT] -m MAPPING [-v] [input]

Replace hostnames and domains based on a provided mapping.

positional arguments:
  input                 input file to read from. If not provided, read from stdin

options:
  -h, --help            show this help message and exit
  -o OUTPUT, --output OUTPUT
                        output file to write the replaced content. If not provided, write to stdout
  -m MAPPING, --mapping MAPPING
                        JSON file that contains the host mapping dictionary (e.g., {"web.example.com": "www.example.net"})
  -v, --verbose         display the replacements made

API

host_map: dict of str:str mappings input_text: str or bytes

replacer = HostnameReplacer(host_map)
output_text = replacer.apply_replacements(input_text)

Limitations

• Does not detect encoded uppercase characters. This typically occurs only when an entire hostname (not just the special characters) is URL or entity encoded.

• Preserving the case of individual characters is not supported. For example, if we were mapping "WWW.example.com" to "example.org", would we capitalize anything?

• Similar ambiguity applies to post-encoding casing (e.g., "%2F" vs "%2f"; "&#x2f" vs "&#X2f"), which can lead to inconsistent representation.

• Does not process binary data beyond searching for exact byte sequences. Encodings that are not straight character-to-sequence translations (such as base64) are not supported.

• Hostnames beginning with a hex code are ambiguous when preceded by "%". For example, should "%00example.com" match "example.com" or "00example.com"?

• International domains have not been tested.

• IPv6 is not supported.