Module: Pikuri::Thunderbird::MailtoUri

Defined in:
lib/pikuri/thunderbird/mailto_uri.rb

Overview

Builds the percent-encoded mailto: URI that MailCompose hands to Thunderbird. The URI is the injection surface — a naive concat lets an attacker-authored body smuggle its own &bcc=exfil@evil.com — so every field value is percent-encoded before it joins the URI:

MailtoUri.build(to: ['a@x.com'], subject: 'Re: hi',
              body: "Line 1\nLine 2 & more")
# => "mailto:a@x.com?subject=Re:%20hi&body=Line%201%0ALine%202%20%26%20more"

Multiple recipients ride comma-separated (the commas stay literal — they delimit addresses; each address is encoded individually). The caller (ComposeGuard) has already split and validated the addresses, so a comma here only ever separates two vetted recipients.

Immutable.

Constant Summary collapse

UNRESERVED =

Bytes kept literal; everything else — the structural & ? = # %, spaces, newlines, and every non-ASCII byte — is percent-encoded. @ stays literal so an address reads as a@x.com (the confirmed-working shape), not a%40x.com. Matched byte-wise (+/n+) so a multibyte body encodes cleanly.

%r{[^A-Za-z0-9\-._~@]}n

Class Method Summary collapse

Class Method Details

.build(to:, cc: [], bcc: [], subject: nil, body: nil) ⇒ String

Returns the mailto: URI.

Parameters:

  • to (Array<String>) —

    validated recipient addresses (may be empty — the human then types the recipient in the opened window).

  • cc (Array<String>) (defaults to: []) —

    validated Cc addresses.

  • bcc (Array<String>) (defaults to: []) —

    validated Bcc addresses.

  • subject (String, nil) (defaults to: nil) —

    subject line, or nil to omit.

  • body (String, nil) (defaults to: nil) —

    plain-text body, or nil to omit.

Returns:

  • (String) —

    the mailto: URI.



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# File 'lib/pikuri/thunderbird/mailto_uri.rb', line 34

def self.build(to:, cc: [], bcc: [], subject: nil, body: nil)
  params = []
  params << "cc=#{encode_list(cc)}" unless cc.empty?
  params << "bcc=#{encode_list(bcc)}" unless bcc.empty?
  params << "subject=#{encode(subject)}" if subject && !subject.empty?
  params << "body=#{encode(body)}" if body && !body.empty?

  uri = "mailto:#{encode_list(to)}"
  params.empty? ? uri : "#{uri}?#{params.join('&')}"
end

.encode(value) ⇒ String

Percent-encode one value byte-wise (uppercase hex).

Parameters:

  • value (String)

Returns:

  • (String) 


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# File 'lib/pikuri/thunderbird/mailto_uri.rb', line 53

def self.encode(value)
  value.to_s.b.gsub(UNRESERVED) { |byte| format('%%%02X', byte.ord) }
end

.encode_list(addrs) ⇒ String

Returns each address percent-encoded, joined by literal commas.

Parameters:

  • addrs (Array<String>)

Returns:

  • (String) —

    each address percent-encoded, joined by literal commas.



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# File 'lib/pikuri/thunderbird/mailto_uri.rb', line 47

def self.encode_list(addrs) = addrs.map { |a| encode(a) }.join(',')