#!/bin/sh
# Triggers an HTTPS connection from the remote Fediverse instance to your host.
# Works only if the remote instance checks signatures. You need an HTTPS server
# running on <Your host> with access logging activated in order for this to
# work.

# Version: 2019-08-17_1

if [ -z "${2}" ]; then
    echo "Usage: ${0} <Your host> <Remote host> [additional curl options]" >&2
    exit 1
fi

your_host="${1}"
remote_host="${2}"

if command -v md5sum > /dev/null; then
    uuid="$(date | md5sum | cut -d' ' -f 1)"
else
    echo "Warning: md5sum not found." >&2
    uuid="4c2896dcba1597e2768387bc1e0e727a"
fi

sig='Signature: keyId="https://'"${your_host}/${uuid}"'",algorithm="rsa-sha256"'
sig="${sig}"',headers="(request-target) host date content-type",signature="Aa="'

curl -H "${sig}" -H "Date: $(date -Ru|sed -e 's/+0000/GMT/')" \
     -H "Content-Type: application/activity+json" -d '{}' "${@}" \
     "https://${remote_host}/inbox"
echo