Add guards for undefined ClientIn

This can happen in sasl2 when initial-response is not provided.

Author: prefiks

src/xmpp_sasl_digest.erl

@@ -132,7 +132,8 @@ mech_step(#state{step = 5, auth_module = AuthModule,
 mech_step(_, _) ->
     {error, unexpected_response}.
 
-parse(S) -> parse1(binary_to_list(S), "", []).
+parse(S) when is_binary(S) -> parse1(binary_to_list(S), "", []);
+parse(_) -> bad.
 
 parse1([$= | Cs], S, Ts) ->
     parse2(Cs, lists:reverse(S), "", Ts);

src/xmpp_sasl_fast.erl

@@ -101,8 +101,8 @@ mech_step(State, ClientIn) ->
 	    {error, parser_failed}
     end.
 
--spec prepare(binary()) -> {binary(), binary()} | error.
-prepare(ClientIn) ->
+-spec prepare(term()) -> {binary(), binary()} | error.
+prepare(ClientIn) when is_binary(ClientIn) ->
     case parse(ClientIn) of
 	[User, Hash] ->
 	    case parse_authzid(User) of
@@ -113,7 +113,8 @@ prepare(ClientIn) ->
 	    end;
 	_ ->
 	    error
-    end.
+    end;
+prepare(_) -> error.
 
 -spec parse(binary()) -> [binary()].
 parse(S) ->

src/xmpp_sasl_plain.erl

@@ -55,8 +55,8 @@ mech_step(State, ClientIn) ->
 	    {error, parser_failed}
     end.
 
--spec prepare(binary()) -> {binary(), binary(), binary()} | error.
-prepare(ClientIn) ->
+-spec prepare(term()) -> {binary(), binary(), binary()} | error.
+prepare(ClientIn) when is_binary(ClientIn) ->
     case parse(ClientIn) of
 	[<<"">>, UserMaybeDomain, Password] ->
 	    case parse_authzid(UserMaybeDomain) of
@@ -74,7 +74,8 @@ prepare(ClientIn) ->
 	    end;
 	_ ->
 	    error
-    end.
+    end;
+prepare(_) -> error.
 
 -spec parse(binary()) -> [binary()].
 parse(S) ->

src/xmpp_sasl_scram.erl

@@ -105,6 +105,8 @@ mech_new(Mech, ChannelBindings, Mechs, _UAId, _Host, #{get_password := GetPasswo
     #state{step = 2, get_password = GetPassword, algo = Algo,
 	channel_bindings = CB, ssdp = Ssdp}.
 
+mech_step(_State, ClientIn) when not is_binary(ClientIn) ->
+    {error, parser_failed};
 mech_step(#state{step = 2, algo = Algo, ssdp = Ssdp} = State, ClientIn) ->
     case re:split(ClientIn, <<",">>, [{return, binary}]) of
       [CBind, _AuthorizationIdentity, UserNameAttribute, ClientNonceAttribute | Extensions] ->