deliver.py - send activitypub payload to mastodon server

deliver.py

"""
Deliver an ActivityPub message to an inbox

This is largely based on a ruby example `deliver.rb` from this blog post:

https://blog.joinmastodon.org/2018/06/how-to-implement-a-basic-activitypub-server/

"""

from datetime import datetime
from time import mktime
import base64
from hashlib import sha256
from wsgiref.handlers import format_date_time
from OpenSSL import crypto
import requests

def http_date_str():
    now = datetime.now()
    stamp = mktime(now.timetuple())
    date_str = format_date_time(stamp)
    return date_str


def deliver(
    *,
    document,
    private_key_path,
    inbox_url,
    host
):
    document_digest = "SHA-256=" + base64.b64encode(sha256(document.encode()).digest()).decode()

    date_str = http_date_str()
    
    signed_string = f"(request-target): post /inbox\nhost: {host}\ndate: {date_str}\ndigest: {document_digest}"

    private_key = crypto.load_privatekey(crypto.FILETYPE_PEM, open(private_key_path).read())
    signature = base64.b64encode(crypto.sign(private_key, signed_string.encode(), "sha256")).decode()

    header = f'keyId="https://your-static-site.example.com/activitypub/actors/you.json#main-key",headers="(request-target) host date digest",signature="{signature}"'

    response = requests.post(
        inbox_url,
        headers={ 'Host': host, 'Date': date_str, 'Signature': header, 'Digest': document_digest },
        data=document
    )    

    return response


response = deliver(
    document=open("activitypub/activities/accept-follow.json").read(),
    private_key_path="private.pem",
    inbox_url=RECIPIENT_INBOX
    host=HOST_SERVER
)

print(response.status_code)
print(response.content)