dotfiles/.local/share/qutebrowser/userscripts/qute-bitwarden

#!/usr/bin/env python3

# SPDX-FileCopyrightText: Chris Braun (cryzed) <cryzed@googlemail.com>
#
# SPDX-License-Identifier: GPL-3.0-or-later

"""
Insert login information using Bitwarden CLI and a dmenu-compatible application
(e.g. dmenu, rofi -dmenu, ...).
"""

USAGE = """The domain of the site has to be in the name of the Bitwarden entry, for example: "github.com/cryzed" or
"websites/github.com".  The login information is inserted by emulating key events using qutebrowser's fake-key command in this manner:
[USERNAME]<Tab>[PASSWORD], which is compatible with almost all login forms.

If enabled, with the `--totp` flag, it will also move the TOTP code to the
clipboard, much like the Firefox add-on.

You must log into Bitwarden CLI using `bw login` prior to use of this script.
The session key will be stored using keyctl for the number of seconds passed to
the --auto-lock option.

To use in qutebrowser, run: `spawn --userscript qute-bitwarden`
"""

EPILOG = """Dependencies: tldextract (Python 3 module), pyperclip (optional
Python module, used for TOTP codes), Bitwarden CLI (1.7.4 is known to work
but older versions may well also work)

WARNING: The login details are viewable as plaintext in qutebrowser's debug log
(qute://log) and might be shared if you decide to submit a crash report!"""

import argparse
import enum
import functools
import os
import shlex
import subprocess
import sys
import json
import tldextract

argument_parser = argparse.ArgumentParser(
    description=__doc__,
    usage=USAGE,
    epilog=EPILOG,
)
argument_parser.add_argument("url", nargs="?", default=os.getenv("QUTE_URL"))
argument_parser.add_argument("--dmenu-invocation", "-d", default="dmenu -i -p Bitwarden", help="Invocation used to execute a dmenu-provider")
argument_parser.add_argument(
    "--password-prompt-invocation",
    "-p",
    default='dmenupass "Master Password"',
    help="Invocation used to prompt the user for their Bitwarden password",
)
argument_parser.add_argument("--no-insert-mode", "-n", dest="insert_mode", action="store_false", help="Don't automatically enter insert mode")
argument_parser.add_argument("--totp", "-t", action="store_true", help="Copy TOTP key to clipboard")
argument_parser.add_argument("--io-encoding", "-i", default="UTF-8", help="Encoding used to communicate with subprocesses")
argument_parser.add_argument("--merge-candidates", "-m", action="store_true", help="Merge pass candidates for fully-qualified and registered domain name")
argument_parser.add_argument("--auto-lock", type=int, default=900, help="Automatically lock the vault after this many seconds")
group = argument_parser.add_mutually_exclusive_group()
group.add_argument("--username-only", "-e", action="store_true", help="Only insert username")
group.add_argument("--password-only", "-w", action="store_true", help="Only insert password")
group.add_argument("--totp-only", "-T", action="store_true", help="Only insert totp code")

stderr = functools.partial(print, file=sys.stderr)


class ExitCodes(enum.IntEnum):
    SUCCESS = 0
    FAILURE = 1
    # 1 is automatically used if Python throws an exception
    NO_PASS_CANDIDATES = 2
    COULD_NOT_MATCH_USERNAME = 3
    COULD_NOT_MATCH_PASSWORD = 4


def qute_command(command):
    with open(os.environ["QUTE_FIFO"], "w") as fifo:
        fifo.write(command + "\n")
        fifo.flush()


def ask_password(password_prompt_invocation):
    process = subprocess.run(
        shlex.split(password_prompt_invocation),
        text=True,
        stdout=subprocess.PIPE,
    )
    if process.returncode > 0:
        raise Exception("Could not unlock vault")
    master_pass = process.stdout.strip()
    return subprocess.check_output(
        ["bw", "unlock", "--raw", "--passwordenv", "BW_MASTERPASS"],
        env={**os.environ, "BW_MASTERPASS": master_pass},
        text=True,
    ).strip()


def get_session_key(auto_lock, password_prompt_invocation):
    if auto_lock == 0:
        subprocess.call(["keyctl", "purge", "user", "bw_session"])
        return ask_password(password_prompt_invocation)
    else:
        process = subprocess.run(
            ["keyctl", "request", "user", "bw_session"],
            text=True,
            stdout=subprocess.PIPE,
        )
        key_id = process.stdout.strip()
        if process.returncode > 0:
            session = ask_password(password_prompt_invocation)
            if not session:
                raise Exception("Could not unlock vault")
            key_id = subprocess.check_output(
                ["keyctl", "add", "user", "bw_session", session, "@u"],
                text=True,
            ).strip()

        if auto_lock > 0:
            subprocess.call(["keyctl", "timeout", str(key_id), str(auto_lock)])
        return subprocess.check_output(
            ["keyctl", "pipe", str(key_id)],
            text=True,
        ).strip()


def pass_(domain, encoding, auto_lock, password_prompt_invocation):
    session_key = get_session_key(auto_lock, password_prompt_invocation)
    process = subprocess.run(
        ["bw", "list", "items", "--nointeraction", "--session", session_key, "--url", domain],
        capture_output=True,
    )

    err = process.stderr.decode(encoding).strip()
    if err:
        msg = "Bitwarden CLI returned for {:s} - {:s}".format(domain, err)
        stderr(msg)

        if "Vault is locked" in err:
            stderr("Bitwarden Vault got locked, trying again with clean session")
            return pass_(domain, encoding, 0, password_prompt_invocation)

    if process.returncode:
        return "[]"

    out = process.stdout.decode(encoding).strip()

    return out


def get_totp_code(selection_id, domain_name, encoding, auto_lock, password_prompt_invocation):
    session_key = get_session_key(auto_lock, password_prompt_invocation)
    process = subprocess.run(
        ["bw", "get", "totp", "--nointeraction", "--session", session_key, selection_id],
        capture_output=True,
    )

    err = process.stderr.decode(encoding).strip()
    if err:
        # domain_name instead of selection_id to make it more user-friendly
        msg = "Bitwarden CLI returned for {:s} - {:s}".format(domain_name, err)
        stderr(msg)

        if "Vault is locked" in err:
            stderr("Bitwarden Vault got locked, trying again with clean session")
            return get_totp_code(selection_id, domain_name, encoding, 0, password_prompt_invocation)

    if process.returncode:
        return "[]"

    out = process.stdout.decode(encoding).strip()

    return out


def dmenu(items, invocation, encoding):
    command = shlex.split(invocation)
    process = subprocess.run(command, input="\n".join(items).encode(encoding), stdout=subprocess.PIPE)
    return process.stdout.decode(encoding).strip()


def fake_key_raw(text):
    for character in text:
        # Escape all characters by default, space requires special handling
        sequence = '" "' if character == " " else r"\{}".format(character)
        qute_command("fake-key {}".format(sequence))


def main(arguments):
    if not arguments.url:
        argument_parser.print_help()
        return ExitCodes.FAILURE

    extract_result = tldextract.extract(arguments.url)

    # Try to find candidates using targets in the following order: fully-qualified domain name (includes subdomains),
    # the registered domain name and finally: the IPv4 address if that's what
    # the URL represents
    candidates = []
    for target in filter(
        None,
        [
            extract_result.fqdn,
            extract_result.registered_domain,
            extract_result.subdomain + "." + extract_result.domain,
            extract_result.domain,
            extract_result.ipv4,
        ],
    ):
        target_candidates = json.loads(
            pass_(
                target,
                arguments.io_encoding,
                arguments.auto_lock,
                arguments.password_prompt_invocation,
            )
        )
        if not target_candidates:
            continue

        candidates = candidates + target_candidates
        if not arguments.merge_candidates:
            break
    else:
        if not candidates:
            stderr("No pass candidates for URL {!r} found!".format(arguments.url))
            return ExitCodes.NO_PASS_CANDIDATES

    if len(candidates) == 1:
        selection = candidates.pop()
    else:
        choices = ["{:s} | {:s}".format(c["name"], c["login"]["username"]) for c in candidates]
        choice = dmenu(choices, arguments.dmenu_invocation, arguments.io_encoding)
        choice_tokens = choice.split("|")
        choice_name = choice_tokens[0].strip()
        choice_username = choice_tokens[1].strip()
        selection = next((c for (i, c) in enumerate(candidates) if c["name"] == choice_name and c["login"]["username"] == choice_username), None)

    # Nothing was selected, simply return
    if not selection:
        return ExitCodes.SUCCESS

    username = selection["login"]["username"]
    password = selection["login"]["password"]
    totp = selection["login"]["totp"]

    if arguments.username_only:
        fake_key_raw(username)
    elif arguments.password_only:
        fake_key_raw(password)
    elif arguments.totp_only:
        # No point in moving it to the clipboard in this case
        fake_key_raw(
            get_totp_code(
                selection["id"],
                selection["name"],
                arguments.io_encoding,
                arguments.auto_lock,
                arguments.password_prompt_invocation,
            )
        )
    else:
        # Enter username and password using fake-key and <Tab> (which seems to work almost universally), then switch
        # back into insert-mode, so the form can be directly submitted by
        # hitting enter afterwards
        fake_key_raw(username)
        qute_command("fake-key <Tab>")
        fake_key_raw(password)

    if arguments.insert_mode:
        qute_command("mode-enter insert")

    # If it finds a TOTP code, it copies it to the clipboard,
    # which is the same behavior as the Firefox add-on.
    if not arguments.totp_only and totp and arguments.totp:
        # The import is done here, to make pyperclip an optional dependency
        import pyperclip

        pyperclip.copy(
            get_totp_code(
                selection["id"],
                selection["name"],
                arguments.io_encoding,
                arguments.auto_lock,
                arguments.password_prompt_invocation,
            )
        )

    return ExitCodes.SUCCESS


if __name__ == "__main__":
    arguments = argument_parser.parse_args()
    sys.exit(main(arguments))