Yet another JSON CLI formatter fix

The bug addressed by this PR was found while running the following
command:

```
rabbitmqctl environment --formatter=json
```

...after configuring the `rabbit` application to use `cacerts` with a
list of binaries as the value, rather than `cacertfile`.

This PR also fixes the formatting of the `tcp_listeners` and
`ssl_listeners` output, because `[5672]` is a valid list of unicode
codepoints that `unicode:characters_to_binary` will happily convert it,
resulting in `"tcp_listeners": "ᘨ"` in the output.

I also ensured that the fixes in #14511 and #14398 still work as
intended.

Author: lukebakken

deps/rabbitmq_cli/lib/rabbitmq/cli/formatters/json.ex

@@ -91,13 +91,29 @@ defmodule RabbitMQ.CLI.Formatters.Json do
     "Ref(#{inspect(data)})"
   end
 
+  defp convert_erlang_strings(data) when is_binary(data) do
+    convert_binary(data)
+  end
+
   defp convert_erlang_strings([]),  do: []
 
-  defp convert_erlang_strings([b | _rest]=data) when is_binary(b) do
-    # Assume this is a list of strings already converted
+  defp convert_erlang_strings([val]=data) when is_integer(val) and val > 255 do
+    # This is likely a value like [5672], which we don't want
+    # to convert to the equivalent unicode codepoint.
+    data
+  end
+
+  defp convert_erlang_strings([v0, v1]=data) when
+    is_integer(v0) and v0 > 255 and is_integer(v1) and v1 > 255 do
+    # This is likely a value like [5672, 5682], which we don't want
+    # to convert to the equivalent unicode codepoint.
     data
   end
 
+  defp convert_erlang_strings([b | rest]) when is_binary(b) do
+      [convert_binary(b) | convert_erlang_strings(rest)]
+  end
+
   defp convert_erlang_strings(data) when is_list(data) do
     try do
       case :unicode.characters_to_binary(data, :utf8) do
@@ -129,4 +145,21 @@ defmodule RabbitMQ.CLI.Formatters.Json do
   end
 
   defp convert_erlang_strings(data), do: data
+
+  defp convert_binary(data) when is_binary(data) do
+    try do
+      case :unicode.characters_to_binary(data, :utf8) do
+        binary when is_binary(binary) ->
+          # Successfully converted - it was a valid Unicode string
+          binary
+        _ ->
+          # Conversion failed - not a Unicode string
+          Base.encode64(data)
+      end
+    rescue
+      ArgumentError ->
+        # badarg exception - just base64 encode it.
+        Base.encode64(data)
+    end
+  end
 end

deps/rabbitmq_cli/test/json_formatting_test.exs

@@ -100,5 +100,9 @@ defmodule JSONFormattingTest do
     assert Map.has_key?(rabbit, "data_dir")
     data_dir = rabbit["data_dir"]
     assert is_binary(data_dir)
+
+    assert Map.has_key?(rabbit, "tcp_listeners")
+    tcp_listeners = rabbit["tcp_listeners"]
+    assert is_list(tcp_listeners)
   end
 end