Add persistent (in cache dir) session_id

rebar.config

@@ -14,7 +14,7 @@
         {enoise, {git, "https://git.qpq.swiss/QPQ-AG/enoise.git", {ref, "029292817e"}}},
         {gmhive_protocol,
          {git, "https://git.qpq.swiss/QPQ-AG/gmhive_protocol.git",
-          {ref, "8d4652a"}}},
+          {ref, "9eec871"}}},
         {gmhive_worker, {git, "https://git.qpq.swiss/QPQ-AG/gmhive_worker", {ref, "cabd104114"}}},
         {gmconfig, {git, "https://git.qpq.swiss/QPQ-AG/gmconfig.git",
                     {ref, "38620ff9e2"}}},

rebar.lock

@@ -25,7 +25,7 @@
   1},
  {<<"gmhive_protocol">>,
   {git,"https://git.qpq.swiss/QPQ-AG/gmhive_protocol.git",
-       {ref,"8d4652a79a2ad8f51e1fe560c15c698d4c92485c"}},
+       {ref,"9eec871e954b729cc5c9249da81abb91de03ad39"}},
   0},
  {<<"gmhive_worker">>,
   {git,"https://git.qpq.swiss/QPQ-AG/gmhive_worker",

src/gmhc_connector.erl

@@ -456,6 +456,7 @@ protocol_connect(Opts, #st{econn = EConn} = S) ->
                   , client => Client
                   , type => Type
                   , nonces => gmhc_server:total_nonces()
+                  , session_id => gmhc_session:session_id()
                   , signature => ""},
     ?LOG_DEBUG("ConnectReq = ~p", [ConnectReq]),
     try gmhp_msgs:encode_connect(ConnectReq, RId) of

src/gmhc_session.erl

@@ -0,0 +1,69 @@
+-module(gmhc_session).
+-vsn("0.8.3").
+
+%% Persistent mining session id, stored separately from the Eureka
+%% connection-info cache. `gmhc_eureka:invalidate_cache/0` must not
+%% delete this file.
+
+-export([ session_id/0
+        , filename/0
+        ]).
+
+-include_lib("kernel/include/logger.hrl").
+
+session_id() ->
+    File = filename(),
+    case read_session_id(File) of
+        {ok, Id} ->
+            Id;
+        {error, _} ->
+            Id = new_session_id(),
+            _ = write_session_id(File, Id),
+            Id
+    end.
+
+filename() ->
+    Pubkey = gmhc_config:get_config([<<"pubkey">>]),
+    Network = gmhc_config:get_config([<<"network">>]),
+    Path = filename:join(gmhc_eureka:cache_dir(), Network),
+    <<"ak_", PKShort:8/binary, _/binary>> = Pubkey,
+    filename:join(Path, "gmhc_session." ++ binary_to_list(PKShort) ++ ".id").
+
+new_session_id() ->
+    gmser_api_encoder:encode(bytearray, crypto:strong_rand_bytes(32)).
+
+read_session_id(File) ->
+    Pubkey = gmhc_config:get_config([<<"pubkey">>]),
+    Network = gmhc_config:get_config([<<"network">>]),
+    case file:read_file(File) of
+        {ok, Bin} ->
+            try binary_to_term(Bin) of
+                #{ session_id := Id
+                 , network := N
+                 , pubkey := PK } when N == Network, PK == Pubkey,
+                                       is_binary(Id) ->
+                    case gmser_api_encoder:safe_decode(bytearray, Id) of
+                        {ok, _} -> {ok, Id};
+                        _ -> {error, invalid_session_id}
+                    end;
+                _ ->
+                    {error, invalid_session_term}
+            catch
+                error:E ->
+                    {error, {invalid_session_data, E}}
+            end;
+        {error, _} = Err ->
+            Err
+    end.
+
+write_session_id(File, Id) ->
+    Term = #{ session_id => Id
+            , pubkey => gmhc_config:get_config([<<"pubkey">>])
+            , network => gmhc_config:get_config([<<"network">>]) },
+    case filelib:ensure_dir(File) of
+        ok ->
+            file:write_file(File, term_to_binary(Term));
+        {error, _} = Err ->
+            ?LOG_ERROR("Cannot save session id to ~s: ~p", [File, Err]),
+            Err
+    end.