mod_sasl2_fast: Fix harmless off-by-one error (invalidates existing tokens!) Problem: This was causing the key to become "<token>--cur" instead of the expected "<token>-cur". As the same key was used by the code to both set and get, it still worked. Rationale for change: Although it worked, it's unintended, inconsistent and messy. It increases the chances of future bugs due to the unexpected format. Side-effects of change: Existing '--cur' entries will not be checked after this change, and therefore existing FAST clients will fail to authenticate until they attempt password auth and obtain a new FAST token. Existing '--cur' entries in storage will not be cleaned up by this commit, but this is considered a minor issue, and okay for the relatively few FAST deployments.

# Introduction

[XEP-0215] implementation for [time-limited TURN
credentials](https://tools.ietf.org/html/draft-uberti-behave-turn-rest-00).

# Configuration

  Option                    Type     Default
  ------------------------- -------- ------------
  turncredentials\_secret   string   *required*
  turncredentials\_host     string   *required*
  turncredentials\_port     number   `3478`
  turncredentials\_ttl      number   `86400`

# Compatible TURN / STUN servers.

-   [coturn](https://github.com/coturn/coturn) - [setup guide][doc:coturn]
-   [restund](http://www.creytiv.com/restund.html)
-   [eturnal](https://eturnal.net/)

# Compatibility

Incompatible with [mod_extdisco](https://modules.prosody.im/mod_extdisco.html)