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
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
|
# frozen_string_literal: true
# Implemented according to HTTP signatures (Draft 6)
# <https://tools.ietf.org/html/draft-cavage-http-signatures-06>
module SignatureVerification
extend ActiveSupport::Concern
include DomainControlHelper
def require_signature!
render plain: signature_verification_failure_reason, status: signature_verification_failure_code unless signed_request_account
end
def signed_request?
request.headers['Signature'].present?
end
def signature_verification_failure_reason
@signature_verification_failure_reason
end
def signature_verification_failure_code
@signature_verification_failure_code || 401
end
def signed_request_account
return @signed_request_account if defined?(@signed_request_account)
unless signed_request?
@signature_verification_failure_reason = 'Request not signed'
@signed_request_account = nil
return
end
if request.headers['Date'].present? && !matches_time_window?
@signature_verification_failure_reason = 'Signed request date outside acceptable time window'
@signed_request_account = nil
return
end
raw_signature = request.headers['Signature']
signature_params = {}
raw_signature.split(',').each do |part|
parsed_parts = part.match(/([a-z]+)="([^"]+)"/i)
next if parsed_parts.nil? || parsed_parts.size != 3
signature_params[parsed_parts[1]] = parsed_parts[2]
end
if incompatible_signature?(signature_params)
@signature_verification_failure_reason = 'Incompatible request signature'
@signed_request_account = nil
return
end
account = account_from_key_id(signature_params['keyId'])
if account.nil?
@signature_verification_failure_reason = "Public key not found for key #{signature_params['keyId']}"
@signed_request_account = nil
return
end
signature = Base64.decode64(signature_params['signature'])
compare_signed_string = build_signed_string(signature_params['headers'])
return account unless verify_signature(account, signature, compare_signed_string).nil?
account = stoplight_wrap_request { account.possibly_stale? ? account.refresh! : account_refresh_key(account) }
if account.nil?
@signature_verification_failure_reason = "Public key not found for key #{signature_params['keyId']}"
@signed_request_account = nil
return
end
return account unless verify_signature(account, signature, compare_signed_string).nil?
@signature_verification_failure_reason = "Verification failed for #{account.username}@#{account.domain} #{account.uri}"
@signed_request_account = nil
end
def request_body
@request_body ||= request.raw_post
end
private
def verify_signature(account, signature, compare_signed_string)
if account.keypair.public_key.verify(OpenSSL::Digest::SHA256.new, signature, compare_signed_string)
@signed_request_account = account
@signed_request_account
end
rescue OpenSSL::PKey::RSAError
nil
end
def build_signed_string(signed_headers)
signed_headers = 'date' if signed_headers.blank?
signed_headers.downcase.split(' ').map do |signed_header|
if signed_header == Request::REQUEST_TARGET
"#{Request::REQUEST_TARGET}: #{request.method.downcase} #{request.path}"
elsif signed_header == 'digest'
"digest: #{body_digest}"
else
"#{signed_header}: #{request.headers[to_header_name(signed_header)]}"
end
end.join("\n")
end
def matches_time_window?
begin
time_sent = Time.httpdate(request.headers['Date'])
rescue ArgumentError
return false
end
(Time.now.utc - time_sent).abs <= 12.hours
end
def body_digest
"SHA-256=#{Digest::SHA256.base64digest(request_body)}"
end
def to_header_name(name)
name.split(/-/).map(&:capitalize).join('-')
end
def incompatible_signature?(signature_params)
signature_params['keyId'].blank? ||
signature_params['signature'].blank?
end
def account_from_key_id(key_id)
domain = key_id.start_with?('acct:') ? key_id.split('@').last : key_id
if domain_not_allowed?(domain)
@signature_verification_failure_code = 403
return
end
if key_id.start_with?('acct:')
stoplight_wrap_request { ResolveAccountService.new.call(key_id.gsub(/\Aacct:/, '')) }
elsif !ActivityPub::TagManager.instance.local_uri?(key_id)
account = ActivityPub::TagManager.instance.uri_to_resource(key_id, Account)
account ||= stoplight_wrap_request { ActivityPub::FetchRemoteKeyService.new.call(key_id, id: false) }
account
end
end
def stoplight_wrap_request(&block)
Stoplight("source:#{request.remote_ip}", &block)
.with_fallback { nil }
.with_threshold(1)
.with_cool_off_time(5.minutes.seconds)
.with_error_handler { |error, handle| error.is_a?(HTTP::Error) ? handle.call(error) : raise(error) }
.run
end
def account_refresh_key(account)
return if account.local?
ActivityPub::FetchRemoteAccountService.new.call(account.uri, only_key: true)
end
end
|