agent: include server address string into BROKER errors (#575)

* agent: include server address string into BROKER errors

* eol

Co-authored-by: JRoberts <8711996+jr-simplex@users.noreply.github.com>

Co-authored-by: JRoberts <8711996+jr-simplex@users.noreply.github.com>

src/Simplex/Messaging/Client.hs

@@ -30,6 +30,7 @@ module Simplex.Messaging.Client
     SMPClient,
     getProtocolClient,
     closeProtocolClient,
+    clientServer,
 
     -- * SMP protocol command functions
     createSMPQueue,
@@ -80,6 +81,7 @@ import GHC.Generics (Generic)
 import Network.Socket (ServiceName)
 import Numeric.Natural
 import qualified Simplex.Messaging.Crypto as C
+import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Parsers (dropPrefix, enumJSON)
 import Simplex.Messaging.Protocol as SMP
 import Simplex.Messaging.TMap (TMap)
@@ -212,6 +214,9 @@ chooseTransportHost NetworkConfig {socksProxy, hostMode, requiredHostMode} hosts
     onionHost = find isOnionHost hosts
     publicHost = find (not . isOnionHost) hosts
 
+clientServer :: ProtocolTypeI (ProtoType msg) => ProtocolClient msg -> String  
+clientServer = B.unpack . strEncode . protocolServer
+
 -- | Connects to 'ProtocolServer' using passed client configuration
 -- and queue for messages and notifications.
 --