1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
# frozen_string_literal: true
# server-server
post '/inbox' do
request.body.rewind # in case someone already read it
@body = request.body.read
halt 400 if @body.empty?
begin
@activity = JSON.parse @body
rescue StandardError
p @body
halt 400
end
halt 501 if @activity['actor'] and @activity['type'] == 'Delete' # deleted actors return 403 => verification error
verify! # unless type == :accept # pixelfed sends unsigned accept activities???
complete_and_save(@activity)
type = @activity['type'].downcase.to_sym
send(type) if %i[follow accept undo].include? type
halt 200
end
# public
get '/.well-known/webfinger' do
halt 404 unless request['resource'] == "acct:#{MENTION}"
send_file(WEBFINGER, type: 'application/jrd+json')
end
get '/pdp8' do
send_file(File.join(PUBLIC_DIR, 'pdp8.json'), type: CONTENT_TYPE)
end
['/following', '/followers'].each do |path|
get path do
send_file(File.join(PUBLIC_DIR, path) + '.json', type: CONTENT_TYPE)
end
end
helpers do
def follow
update_collection FOLLOWERS, @activity['actor']
outbox 'Accept', @activity, [@activity['actor']]
end
def accept
halt 501 unless @activity['object']['type'] == 'Follow'
update_collection FOLLOWING, @activity['object']['object']
end
def undo
halt 501 unless @activity['object']['type'] == 'Follow'
update_collection FOLLOWERS, @activity['object']['actor'], true
end
# https://github.com/mastodon/mastodon/blob/main/app/controllers/concerns/signature_verification.rb
def verify!
# digest
sha256 = OpenSSL::Digest.new('SHA256')
digest = "SHA-256=#{sha256.base64digest(@body)}"
halt 403 unless digest == request.env['HTTP_DIGEST']
# signature
signature_params = {}
request.env['HTTP_SIGNATURE'].split(',').each do |pair|
k, v = pair.split('=')
signature_params[k] = v.gsub('"', '')
end
key_id = signature_params['keyId']
headers = signature_params['headers']
signature = Base64.decode64(signature_params['signature'])
actor = fetch key_id
halt 403 unless actor
key = OpenSSL::PKey::RSA.new(actor['publicKey']['publicKeyPem'])
comparison = headers.split(' ').map do |signed_params_name|
if signed_params_name == '(request-target)'
'(request-target): post /inbox'
elsif signed_params_name == 'content-type'
"#{signed_params_name}: #{request.env['CONTENT_TYPE']}"
else
"#{signed_params_name}: #{request.env["HTTP_#{signed_params_name.upcase}"]}"
end
end.join("\n")
halt 403 unless key.verify(OpenSSL::Digest.new('SHA256'), signature, comparison)
end
def outbox(type, object, recipients)
# add date and id, save
activity = complete_and_save({
'@context' => 'https://www.w3.org/ns/activitystreams',
'type' => type,
'actor' => ACTOR,
'object' => object,
'to' => recipients
})
# send
# https://github.com/mastodon/mastodon/blob/main/app/lib/request.rb
keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
body = activity.to_json
sha256 = OpenSSL::Digest.new('SHA256')
digest = "SHA-256=#{sha256.base64digest(body)}"
inboxes = []
recipients.uniq.each do |url|
next if [ACTOR, 'https://www.w3.org/ns/activitystreams#Public'].include? url
actor = fetch url
next unless actor
if actor['endpoints'] and actor['endpoints']['sharedInbox']
inboxes << actor['endpoints']['sharedInbox']
elsif actor['inbox']
inboxes << actor['inbox']
end
end
inboxes.compact.uniq.each do |inbox|
uri = URI(inbox)
string = "(request-target): post #{uri.request_uri}\nhost: #{uri.host}\ndate: #{httpdate}\ndigest: #{digest}\ncontent-type: application/activity+json"
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 digest content-type\",signature=\"#{signature}\""
curl(
"-X POST -H 'Content-Type: application/activity+json' -H 'Host: #{uri.host}' -H 'Date: #{httpdate}' -H 'Digest: #{digest}' -H 'Signature: #{signed_header}' -d '#{body}'", inbox
)
end
activity
end
end
|
