mod_invites: Unicode not supported in site_name

[toastal]

Environment

• ejabberd version: 26.03
• Erlang version: whatever is in the Nixpkgs closure (probably latest stable)
• OS: Linux (NixOS)
• Installed from: Nixpkgs + 26.03 patch + add --enable-bootstrap=no to configure options to bypass download #4558 patch

Configuration (only if needed): grep -Ev '^$|^\s*#' ejabberd.yml

modules:
   mod_invites:
      # Using typographically-correct apostrophe;
      # `'` is incorrect.
      site_name: toastal’s XMPP Server

I also tried Thai characters which also crashed on startup. It seemed some non-ASCII Latin characters passed.

Errors from error.log/crash.log

2026-04-03 19:55:31.393837+07:00 [critical] <0.119.0>@ejabberd_app:start/2:79 Failed to start ejabberd application: Exception occurred during configuration processing. This is most likely due to faulty/incompatible validator in third-party code. If you are not running any third-party code, please report the bug with ejabberd configuration file attached and the following stacktrace included:
** exception error: bad argument
   in function  iolist_to_binary/1
      called as iolist_to_binary([116,111,97,115,116,97,108,8217,115,32,88,77,
                                  80,80,32,83,101,114,118,101,114,32,105,110,
                                  32,84,104,97,105,108,97,110,100])
      *** argument 1: not an iodata term
   in call from ejabberd_config:replace_keywords/3 (/build/source/src/ejabberd_config.erl:440)
   in call from yconf:'-and_then/2-fun-0-'/3 (yconf.erl:620)
   in call from yconf:validate_option/3 (yconf.erl:1281)
   in call from yconf:validate_options/8 (yconf.erl:1258)
   in call from yconf:'-and_then/2-fun-0-'/3 (yconf.erl:620)
   in call from yconf:validate_option/3 (yconf.erl:1281)
   in call from yconf:validate_options/8 (yconf.erl:1258)

Bug description

The world has a beautiful tapestry of writing scripts (including punctuation), but many can’t be used in the invite page’s site name.

[sstrigler]

Looks like a general problem with ejabberd_config.

[toastal]

116,111,97,115,116,97,108,8217

is t,o,a,s,t,a,l,’. If I remove the ’ the issue goes away, but I want to use ’ for possession. Looking at the generated config from Nixpkgs’s toYAML, it didn’t seem like there was any issues it’s reencoding of Nix to YAML.

Is there a “general problem” with character limitation in the Ejabberd config beyond just this spot I tried it?

[sstrigler]

I think this is the only place where we use a fully textual description (except for welcome message, which is multi-line).

If you put your string in double quotes, the problem goes away. I.e.

    site_name: "toastal’s XMPP Server"

I just wrote “Problem with ejabberd_config because there’s nothing “mod_invites” specific about the problem. Now that I think about it, it’s more likely an issue with yconf. But I don’t know much about either. Or it might just be a limitation of YAML. No expert here. All I’m saying, this needs some other than me to look into this.

[toastal]

This sounds a lot more plausible than it being one specific place 😅

[sstrigler]

Just confirmed, this problems also exists for mod_register’s welcome_message:

  mod_register:
    welcome_message:
      subject: toastal’s XMPP Server
      body: |-
        toastal’s XMPP Server

body works, but not with subject like this.

[toastal]

I tried escaping in Nix with "\"toastal’s XMPP server\"" which output '"toastal’s XMPP Server in Thailand"'… this still failed (& isn’t the desired output). "\"toastal's XMPP Server in Thailand\"" worked (again by substituting the wrong character for apostrophes). I don’t see why toastal’s XMPP Server should require strings according to the spec. Being in Nix, I don’t have such fine-grained control over the YAML output (tho I could use sed in a fixup phase).

[toastal]

Trying to use the base macro system with INVITES_SITE_NAME: toastal’s XMPP Server in Thailand did not work.

[toastal]

Using the macro environment variables EJABBERD_MACRO_INVITES_SITE_NAME="toastal’s XMPP Server" & EJABBERD_MACRO_INVITES_SITE_NAME="\"toastal’s XMPP Server in Thailand\"" also failed. Which to me shows something more fundamental.

** exception error: bad argument
   in function  fast_yaml:nif_decode/2
      called as fast_yaml:nif_decode([116,111,97,115,116,97,108,8217,115,32,
                                      88,77,80,80,32,83,101,114,118,101,114],
                                     0)
   in call from fast_yaml:decode/2 (fast_yaml.erl:110)
   in call from ejabberd_config:parse_macro_string/1 (/build/source/src/ejabberd_config.erl:705)
   in call from ejabberd_config:'-get_additional_macros/0-fun-0-'/2 (/build/source/src/ejabberd_config.erl:695)
   in call from lists:foldl_1/3 (lists.erl:2471)
   in call from ejabberd_config:get_additional_macros/0 (/build/source/src/ejabberd_config.erl:694)
   in call from ejabberd_config:read_yaml_files/2 (/build/source/src/ejabberd_config.erl:709)
   in call from ejabberd_config:read_file/2 (/build/source/src/ejabberd_config.erl:676)