deserialisation of DHT messages

Hash2Pub/src/Hash2Pub/ASN1Coding.hs

@@ -4,14 +4,16 @@ module Hash2Pub.ASN1Coding where
 
 import Data.ASN1.Encoding -- asn1-encoding package
 import Data.ASN1.BinaryEncoding
-import Data.ASN1.Error
+import Data.ASN1.Error()
 import Data.ASN1.Types -- asn1-types package
 import Data.ASN1.Parse
 import Data.Maybe (fromMaybe, mapMaybe)
-import Data.Time.Clock.POSIX
+import Data.Time.Clock.POSIX()
 import qualified Data.ByteString as BS
 import qualified Data.Set as Set
-import qualified Data.Map.Strict as Map
+import qualified Data.Map.Strict as Map()
+import Data.Bifunctor (first)
+import Control.Exception (displayException)
 import Safe
 
 import Hash2Pub.FediChord
@@ -159,6 +161,11 @@ serialiseMessage msg maxBytesLength =
         maxMsgLength msgs = maximum $ map BS.length msgs
         maximumParts = 150
 
+-- | Deserialise a ASN.1 DER encoded bytesstring of a single 'FediChordMessage'.
+deserialiseMessage :: BS.ByteString
+                   -> Either String FediChordMessage
+deserialiseMessage msgBytes = first displayException (decodeASN1' DER msgBytes) >>= runParseASN1 parseMessage
+
 -- ===== encoding functions =====
 
 -- encode a message 'ActionPayload' according to its type,