From 2e614738f72c9af634c4a630693d06f144bc24df Mon Sep 17 00:00:00 2001
From: pdp8 <pdp8@pdp8.info>
Date: Wed, 12 Jul 2023 14:49:22 +0200
Subject: signed fetch for mastodon instances with AUTHORIZED_FETCH (e.g.
 mastodon.art)

---
 helpers.rb | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

(limited to 'helpers.rb')

diff --git a/helpers.rb b/helpers.rb
index 556f187..212c406 100644
--- a/helpers.rb
+++ b/helpers.rb
@@ -6,11 +6,26 @@ helpers do
   def curl(ext, url)
     p url
     response = `/run/current-system/sw/bin/curl --fail-with-body -sSL #{ext} #{url}`
-    $CHILD_STATUS.success? ? response : nil
+    if $CHILD_STATUS.success?
+      response
+    else
+      p response
+      nil
+    end
   end
 
   def fetch(url, accept = 'application/activity+json')
-    response = curl("-H 'Accept: #{accept}'", url)
+    uri = URI(url)
+    httpdate = Time.now.utc.httpdate
+    keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
+    string = "(request-target): get #{uri.request_uri}\nhost: #{uri.host}\ndate: #{httpdate}"
+    signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest.new('SHA256'), string))
+    signed_header = "keyId=\"#{ACTOR}#main-key\",algorithm=\"rsa-sha256\",headers=\"(request-target) host date\",signature=\"#{signature}\""
+
+    response = curl(
+      "-H 'Accept: #{accept}' -H 'Host: #{uri.host}' -H 'Date: #{httpdate}' -H 'Signature: #{signed_header}' ", url
+    )
+    # response = curl("-H 'Accept: #{accept}'", url)
     response ? JSON.parse(response) : nil
   end
 
@@ -30,7 +45,7 @@ helpers do
     basename = "#{date}.json"
     activity['id'] = File.join(OUTBOX_URL, basename)
     activity['published'] = httpdate
-    if activity['object'] and activity['object']['type'] and !activity['object']['id']
+    if activity['object'] && activity['object']['type'] && !activity['object']['id']
       rel_path = File.join activity['object']['type'].downcase, basename
       activity['object']['published'] = httpdate
       activity['object']['id'] = File.join(OUTBOX_URL, rel_path)
@@ -46,16 +61,19 @@ helpers do
     # assumes that recipient collections have been expanded by sender
     # put all recipients into 'to', avoid 'cc' 'bto' 'bcc' 'audience' !!
     activity['to'] = recipients if add_recipients
-    inboxes = if recipients.include? 'https://www.w3.org/ns/activitystreams#Public'
-                people.collect { |p| p[2] }.uniq # cached sharedInboxes
-              else
-                []
-              end
+    inboxes = []
+    # inboxes = if recipients.include? 'https://www.w3.org/ns/activitystreams#Public'
+    # people.collect { |p| p[2] }.uniq # cached sharedInboxes
+    # else
+    # []
+    # end
     recipients.uniq.each do |url|
       next if [ACTOR, 'https://www.w3.org/ns/activitystreams#Public'].include? url
 
+      p 'FETCH', url
       actor = fetch url
-      next unless actor and actor['inbox']
+      p actor
+      next unless actor && actor['inbox']
 
       inbox = actor['endpoints']['sharedInbox']
       inboxes << (inbox || actor['inbox'])
@@ -109,7 +127,7 @@ helpers do
   end
 
   def cache(mention, actor, a)
-    sharedInbox = a['endpoints']['sharedInbox'] if a['endpoints'] and a['endpoints']['sharedInbox']
+    sharedInbox = a['endpoints']['sharedInbox'] if a['endpoints'] && a['endpoints']['sharedInbox']
     File.open('cache/people.tsv', 'a') { |f| f.puts "#{mention}\t#{actor}\t#{sharedInbox}" }
   end
 end
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