Adds BATV prvs capabilities

lib/email_address/address.rb

@@ -21,20 +21,26 @@ class Address
     # instance, and initializes the address to the "normalized" format of the
     # address. The original string is available in the #original method.
     def initialize(email_address, config={})
-      email_address  = email_address.strip if email_address
+      @config        = config # This needs refactoring!
+      email_address  = (email_address || "").strip
       @original      = email_address
-      email_address||= ""
       email_address  = parse_rewritten(email_address) unless config[:skip_rewrite]
-      if lh = email_address.match(/(.+)@(.+)/)
-        (_, local, host) = lh.to_a
-      else
-        (local, host)    = [email_address, '']
-      end
+      local, host    = EmailAddress::Address.split_local_host(email_address)
+
       @host         = EmailAddress::Host.new(host, config)
       @config       = @host.config
       @local        = EmailAddress::Local.new(local, @config, @host)
     end
 
+    # Given an email address, this returns an array of [local, host] parts
+    def self.split_local_host(email)
+      if lh = email.match(/(.+)@(.+)/)
+        lh.to_a[1,2]
+      else
+        [email, '']
+      end
+    end
+
     ############################################################################
     # Local Part (left of @) access
     # * local: Access full local part instance

lib/email_address/rewriter.rb

@@ -61,34 +61,82 @@ def srs_tt(t=Time.now.utc)
   end
 
   def srs_hash(email, options={}, &block)
+    key = options[:key] || @config[:key] || email.reverse
     if block_given?
       block.call(email)[0,4]
-    elsif options[:secret]
-      Base64.encode64(Digest::SHA1.digest(email + options[:secret].to_s))[0,4]
     else
-      # Non-Secure signing. Please give a secret
-      Base64.encode64(Digest::SHA1.digest(email.reverse))[0,4]
+      Base64.encode64(Digest::SHA1.digest(email + key))[0,4]
     end
   end
 
-  # BATV - Returns the Bounce Address Tag Validation format
+  #---------------------------------------------------------------------------
+  # Returns a BATV form email address with "Private Signature" (prvs).
+  # Options: key: 0-9 key digit to use
+  #          key_0..key_9: secret key used to sign/verify
+  #          prvs_days: number of days before address "expires"
+  #
+  # BATV - Bounce Address Tag Validation
   # PRVS - Simple Private Signature
-  # Ex:    prvs=KDDDSSSS=pat@example.com
+  # Ex:    prvs=KDDDSSSS=user@example.com
   #        * K: Digit for Key rotation
   #        * DDD: Expiry date, since 1970, low 3 digits
   #        * SSSSSS: sha1( KDDD + orig-mailfrom + key)[0,6]
-  # Source: https://tools.ietf.org/html/draft-levine-smtp-batv-01
-  def batv_prvs()
-    raise "Not yet implemented"
+  # See:   https://tools.ietf.org/html/draft-levine-smtp-batv-01
+  #---------------------------------------------------------------------------
+  def batv_prvs(options={})
+    k = options[:prvs_key_id] || "0"
+    prvs_days = options[:prvs_days] || @config[:prvs_days] || 30
+    ddd = prvs_day(prvs_days)
+    ssssss = prvs_sign(k, ddd, self.to_s, options={})
+    ["prvs=", k, ddd, ssssss, '=', self.to_s].join('')
+  end
+
+  PRVS_REGEX = /\Aprvs=(\d)(\d{3})(\w{6})=(.+)\z/
+
+  def parse_prvs(email, options={})
+    if email.match(PRVS_REGEX)
+      @rewrite_scheme = :prvs
+      k, ddd, ssssss, email = [$1, $2, $3, $4]
+
+      unless ssssss == prvs_sign(k, ddd, email, options)
+        @rewrite_error = "Invalid BATV Address: Signature unverified"
+      end
+      exp = ddd.to_i
+      roll = 1000 - exp # rolling 1000 day window
+      today = prvs_day(0)
+      # I'm sure this is wrong
+      if exp > today && exp < roll
+        @rewrite_error = "Invalid SRS Email Address: Address expired"
+      elsif exp < today && (today - exp) > 0
+        @rewrite_error = "Invalid SRS Email Address: Address expired"
+      end
+      [local, domain].join("@")
+    else
+      email
+    end
+  end
+
+  def prvs_day(days)
+    ((Time.now.to_i + (days*24*60*60)) / (24*60*60)).to_s[-3,3]
   end
 
+  def prvs_sign(k, ddd, email, options={})
+    str = [ddd, ssssss, '=', self.to_s].join('')
+    key = options["key_#{k}".to_i] || @config["key_#{k}".to_i] || str.reverse
+    Digest::SHA1.hexdigest([k,ddd, email, key].join(''))[0,6]
+  end
+
+  #---------------------------------------------------------------------------
   # VERP Embeds a recipient email address into the bounce address
   #   Bounce Address:  [email protected]
-  #   Recipient Email: [email protected]
-  #   VERP :           [email protected]
-  def verp(recipient, split_char='+', verp_at='=')
+  #   Recipient Email: [email protected]
+  #   VERP :           [email protected]
+  # To handle incoming verp, the "tag" is the recipient email address,
+  # remember to convert the last '=' into a '@' to reconstruct it.
+  #---------------------------------------------------------------------------
+  def verp(recipient, split_char='+')
     self.local.to_s +
-      split_char + recipient.gsub("@",verp_at) +
+      split_char + recipient.gsub("@","=") +
       "@" + self.hostname
   end