Limnoria/plugins/Fediverse/plugin.py

###
# Copyright (c) 2020, Valentin Lorentz
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions, and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions, and the following disclaimer in the
#     documentation and/or other materials provided with the distribution.
#   * Neither the name of the author of this software nor the name of
#     contributors to this software may be used to endorse or promote products
#     derived from this software without specific prior written consent.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

###

import re
import json
import importlib
import urllib.parse

from supybot import utils, callbacks, httpserver
from supybot.commands import urlSnarfer, wrap
from supybot.i18n import PluginInternationalization

from . import activitypub as ap


importlib.reload(ap)


_ = PluginInternationalization("Fediverse")


_username_regexp = re.compile("@(?P<localuser>[^@ ]+)@(?P<hostname>[^@ ]+)")


class FediverseHttp(httpserver.SupyHTTPServerCallback):
    name = "minimal ActivityPub server"
    defaultResponse = _(
        """
    You shouldn't be here, this subfolder is not for you. Go back to the
    index and try out other plugins (if any)."""
    )

    def doGetOrHead(self, handler, path, write_content):
        if path == "/instance_actor":
            self.instance_actor(write_content)
        else:
            assert False, repr(path)

    def doWellKnown(self, handler, path):
        actor_url = ap.get_instance_actor_url()
        instance_hostname = urllib.parse.urlsplit(actor_url).hostname
        instance_account = "acct:%s@%s" % (
            instance_hostname,
            instance_hostname,
        )
        if path == "/webfinger?resource=%s" % instance_account:
            headers = {"Content-Type": "application/jrd+json"}
            content = {
                "subject": instance_account,
                "links": [
                    {
                        "rel": "self",
                        "type": "application/activity+json",
                        "href": actor_url,
                    }
                ],
            }
            return (200, headers, json.dumps(content).encode())
        else:
            return None

    def instance_actor(self, write_content):
        self.send_response(200)
        self.send_header("Content-type", ap.ACTIVITY_MIMETYPE)
        self.end_headers()
        if not write_content:
            return
        pem = ap.get_public_key_pem()
        actor_url = ap.get_instance_actor_url()
        hostname = urllib.parse.urlparse(actor_url).hostname
        actor = {
            "@context": [
                "https://www.w3.org/ns/activitystreams",
                "https://w3id.org/security/v1",
            ],
            "id": actor_url,
            "preferredUsername": hostname,
            "type": "Service",
            "publicKey": {
                "id": actor_url + "#main-key",
                "owner": actor_url,
                "publicKeyPem": pem.decode(),
            },
            "inbox": actor_url + "/inbox",
        }
        self.wfile.write(json.dumps(actor).encode())


class Fediverse(callbacks.PluginRegexp):
    """Fetches information from ActivityPub servers."""

    threaded = True
    regexps = ["usernameSnarfer", "urlSnarfer_"]
    callBefore = ("Web",)

    def __init__(self, irc):
        super().__init__(irc)
        self._startHttp()
        self._actor_cache = utils.structures.TimeoutDict(timeout=600)

        # Used when snarfing, to cheaply avoid querying non-ActivityPub
        # servers.
        # Is also written to when using commands that successfully find
        # ActivityPub data.
        self._webfinger_support_cache = utils.structures.TimeoutDict(
            timeout=60 * 60 * 24
        )

    def _startHttp(self):
        callback = FediverseHttp()
        callback._plugin = self
        httpserver.hook("fediverse", callback)

    def die(self):
        self._stopHttp()
        super().die()

    def _stopHttp(self):
        httpserver.unhook("fediverse")

    def _has_webfinger_support(self, hostname):
        if hostname not in self._webfinger_support_cache:
            self._webfinger_support_cache[hostname] = ap.has_webfinger_support(
                hostname
            )
        return self._webfinger_support_cache[hostname]

    def _get_actor(self, irc, username):
        if username in self._actor_cache:
            return self._actor_cache[username]
        match = _username_regexp.match(username)
        if match:
            localuser = match.group("localuser")
            hostname = match.group("hostname")

            try:
                actor = ap.get_actor(localuser, hostname)
            except ap.ActorNotFound:
                irc.error("Unknown user %s." % username, Raise=True)
        else:
            match = utils.web.urlRe.match(username)
            if match:
                # TODO: error handling
                actor = ap.get_resource_from_url(match.group(0))
                try:
                    hostname = urllib.parse.urlparse(actor.get("id")).hostname
                    username = "@%s@%s" % (
                        hostname,
                        actor.get["preferredUsername"],
                    )
                except Exception:
                    username = None
            else:
                irc.errorInvalid("fediverse username", username)

        if username:
            self._actor_cache[username] = actor
            self._webfinger_support_cache[hostname] = True

        self._actor_cache[actor["id"]] = actor

        return actor

    def _format_actor_fullname(self, actor):
        try:
            hostname = urllib.parse.urlparse(actor.get("id")).hostname
        except Exception:
            hostname = "<unknown>"
        username = actor.get("preferredUsername", "<unknown>")
        name = actor.get("name", username)
        return "\x02%s\x02 (@%s@%s)" % (name, username, hostname)

    def _format_status(self, irc, msg, status):
        if status["type"] == "Create":
            return self._format_status(irc, msg, status["object"])
        elif status["type"] == "Note":
            author_url = status["attributedTo"]
            try:
                author = self._get_actor(irc, author_url)
            except ap.ActivityPubError as e:
                author_fullname = _("<error: %s>") % str(e)
            else:
                author_fullname = self._format_actor_fullname(author)
            cw = status.get("summary")
            if cw:
                if self.registryValue(
                    "format.statuses.showContentWithCW",
                    msg.channel,
                    irc.network,
                ):
                    # show CW and content
                    res = [_("%s: \x02[CW %s]\x02 %s") % (
                        author_fullname,
                        cw,
                        utils.web.htmlToText(status["content"]),
                    )]
                else:
                    # show CW but not content
                    res = [_("%s: CW %s") % (author_fullname, cw)]
            else:
                # no CW, show content
                res = [_("%s: %s") % (
                    author_fullname,
                    utils.web.htmlToText(status["content"]),
                )]

            for attachment in status.get("attachment", []):
                res.append(utils.str.url(attachment.get("url")))
            return " ".join(res)
        elif status["type"] == "Announce":
            # aka boost; let's go fetch the original status
            try:
                content = ap.signed_request(
                    status["object"], headers={"Accept": ap.ACTIVITY_MIMETYPE}
                )
                status = json.loads(content.decode())
                return self._format_status(irc, msg, status)
            except ap.ActivityPubProtocolError as e:
                return "<Could not fetch status: %s>" % e.args[0]
        else:
            assert False, "Unknown status type %s: %r" % (
                status["type"],
                status,
            )

    @wrap(["somethingWithoutSpaces"])
    def profile(self, irc, msg, args, username):
        """<@user@instance>

        Returns generic information on the account @user@instance."""
        actor = self._get_actor(irc, username)

        irc.reply(
            _("%s: %s")
            % (
                self._format_actor_fullname(actor),
                utils.web.htmlToText(actor["summary"]),
            )
        )

    def _format_profile(self, irc, msg, actor):
        return _("%s: %s") % (
            self._format_actor_fullname(actor),
            utils.web.htmlToText(actor["summary"]),
        )

    def usernameSnarfer(self, irc, msg, match):
        if callbacks.addressed(irc, msg):
            return
        if not self.registryValue(
            "snarfers.username", msg.channel, irc.network
        ):
            return

        if not self._has_webfinger_support(match.group("hostname")):
            self.log.debug(
                "Not snarfing, host doesn't have Webfinger support."
            )
            return

        try:
            actor = self._get_actor(irc, match.group(0))
        except ap.ActivityPubError as e:
            self.log.info("Could not fetch %s: %s", match.group(0), e)
            # Be silent on errors
            return

        irc.reply(self._format_profile(irc, msg, actor))

    usernameSnarfer.__doc__ = _username_regexp.pattern

    @urlSnarfer
    def urlSnarfer_(self, irc, msg, match):
        channel = msg.channel
        network = irc.network
        url = match.group(0)
        if not channel:
            return
        if callbacks.addressed(irc, msg):
            return
        snarf_profile = self.registryValue(
            "snarfers.profile", channel, network
        )
        snarf_status = self.registryValue("snarfers.status", channel, network)
        if not snarf_profile and not snarf_status:
            return

        hostname = urllib.parse.urlparse(url).hostname
        if not self._has_webfinger_support(hostname):
            self.log.debug(
                "Not snarfing, host doesn't have Webfinger support."
            )
            return

        try:
            resource = ap.get_resource_from_url(url)
        except ap.ActivityPubError:
            return

        try:
            if snarf_profile and resource["type"] in ("Person", "Service"):
                irc.reply(self._format_profile(irc, msg, resource))
            elif snarf_status and resource["type"] in (
                "Create",
                "Note",
                "Announce",
            ):
                irc.reply(self._format_status(irc, msg, resource))
        except ap.ActivityPubError:
            return

    urlSnarfer_.__doc__ = utils.web._httpUrlRe

    @wrap(["somethingWithoutSpaces"])
    def featured(self, irc, msg, args, username):
        """<@user@instance>

        Returnes the featured statuses of @user@instance (aka. pinned toots).
        """
        actor = self._get_actor(irc, username)
        if "featured" not in actor:
            irc.reply(_("No featured statuses."))
            return
        statuses = json.loads(
            ap.signed_request(actor["featured"]).decode()
        ).get("orderedItems", [])
        if not statuses:
            irc.reply(_("No featured statuses."))
            return
        irc.replies(
            filter(
                bool,
                (self._format_status(irc, msg, status) for status in statuses),
            )
        )

    @wrap(["somethingWithoutSpaces"])
    def statuses(self, irc, msg, args, username):
        """<@user@instance>

        Returned the last statuses of @user@instance.
        """
        actor = self._get_actor(irc, username)
        if "outbox" not in actor:
            irc.error(_("No status."), Raise=True)
        outbox = json.loads(ap.signed_request(actor["outbox"]).decode())

        # Fetches the first page of the outbox. This should be a good-enough
        # approximation of the number of statuses to show.
        statuses = json.loads(ap.signed_request(outbox["first"]).decode()).get(
            "orderedItems", []
        )
        irc.replies(
            filter(
                bool,
                (self._format_status(irc, msg, status) for status in statuses),
            )
        )

    @wrap(["url"])
    def status(self, irc, msg, args, url):
        """<url>

        Shows the content of the status at <url>.
        """
        try:
            status = ap.get_resource_from_url(url)
        except ap.ActivityPubError as e:
            irc.error(_("Could not get status: %s") % e.args[0], Raise=True)
        else:
            hostname = urllib.parse.urlparse(url).hostname
            self._webfinger_support_cache[hostname] = True

        irc.reply(self._format_status(irc, msg, status))


Class = Fediverse


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