DMARC: first baby steps towards an implementation of the type.

src/App/Type/DMARC.purs

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+module App.Type.DMARC where
+
+import Prelude
+import Data.Generic.Rep (class Generic)
+import Data.Show.Generic (genericShow)
+
+import App.Type.GenericSerialization (generic_serialization)
+import Data.Maybe (Maybe(..))
+
+import Data.Codec.Argonaut (JsonCodec)
+import Data.Codec.Argonaut as CA
+import Data.Codec.Argonaut.Record as CAR
+
+type DMARC
+  = {
+    -- | adkim= Optional.
+    -- | Consistency policy for DKIM. Either strict (dkim signature domain = "From:" field) or relaxed.
+      adkim :: Maybe ConsistencyPolicy
+    -- | aspf= Optional.
+    -- | Consistency policy for SPF. Either strict (dkim signature domain = "From:" field) or relaxed.
+    , aspf :: Maybe ConsistencyPolicy
+    -- | v= "DMARC1", entirely optional (for now, even ignored).
+    , v :: Maybe Version
+    -- | pct= Percentage of messages to filter [0...100], 100 by default.
+    , pct :: Int
+    -- | p= Requested Mail Receiver policy (None, Quarantine, Reject).
+    , p :: Policy
+    -- | sp= Requested Mail Receiver policy for all subdomains.
+    , sp :: Policy
+    -- | ruf= Addresses to which message-specific failure information is to be reported.
+    , ruf :: MailTo
+    -- | fo= When to send a report (on DKIM or SPF error? Any? Both?).
+    , fo :: Maybe ReportOccasion
+    -- | rua= Where to send the aggregated reports. A size limit can be provided (see `rua_maxlen`).
+    , rua :: MailTo
+    -- | Optional. !XXm Max size of the report (in megabytes).
+    , rua_maxlen :: Maybe Int
+    -- | rf= Optional. Report format, AFRF by default.
+    , rf :: Maybe Format
+    -- | ri= Optional. Interval requested between aggregate reports. By default 86400.
+    , ri :: Maybe Int
+    }
+
+data ReportOccasion = Both | DKIMonly | SPFonly | AnyOccasion
+
+data ConsistencyPolicy
+  -- | s = strict.
+  -- |
+  -- | For DKIM: DKIM signature and "From:" field should have the exact same domain.
+  -- |
+  -- | For SPF: First, SPF should produce a passing result. Then, the "From:" and the "MailFrom:" fields are checked.
+  -- | In strict mode, Both "MailFrom:" and "From:" fields should have the same value.
+  -- |
+  -- | From RFC7489: For example, if a message passes an SPF check with an
+  -- | RFC5321.MailFrom domain of "cbg.bounces.example.com", and the address
+  -- | portion of the RFC5322.From field contains "payments@example.com",
+  -- | the Authenticated RFC5321.MailFrom domain identifier and the
+  -- | RFC5322.From domain are considered to be "in alignment" in relaxed
+  -- | mode, but not in strict mode.
+  = Strict
+  -- | r = relaxed, default.
+  -- |
+  -- | For DKIM: "From:" field can be in the same domain of the domain of the DKIM signature.
+  -- | Example: "From:" is example@foo.example.org, DKIM signature can be d=example.org or d=bar.example.org.
+  -- |
+  -- | For SPF:
+  | Relaxed
+
+data Format = AFRF -- Authentication Failure Reporting Format
+data Version = DMARC1
+data Policy
+  -- | "None" means to basically just accept the mail.
+  = None
+  -- | "Quarantine" means to consider the mail as suspicious, by giving it a bad spam score or something like that.
+  | Quarantine
+  -- | "Reject" means to not accept any failure of DKIM or SPF.
+  | Reject
+
+type MailTo = String