Implement basic IRCv3 SASL PLAIN authentication

[tsautier]

Problem

SiteBot could not connect to modern IRC networks that require IRCv3 SASL authentication. The existing IRC client implementation lacked CAP negotiation and SASL support.

Solution

Implement IRCv3 SASL PLAIN authentication in the SiteBot module without a full library rewrite.

Changes Made

1. Configuration (ServerConfig.java)

• Added _saslUsername and _saslPassword fields
• Added getter methods getSaslUsername() and getSaslPassword()

2. Config Parsing (SiteBotConfig.java)

• Modified readProperties() to parse server.X.sasl.username and server.X.sasl.password

3. Connection Logic (SiteBot.java)

• Added CAP LS 302 command on connection when SASL credentials are configured
• Handle CAP negotiation (CAP REQ :sasl, CAP ACK, CAP NAK)
• Send AUTHENTICATE PLAIN with Base64-encoded credentials
• Handle SASL response codes:
  • 903 = Success → send CAP END
  • 904/905 = Failure → log error and disconnect

4. Configuration Template (irc.conf.dist)

Added example configuration:

server.1.sasl.username=mybot
server.1.sasl.password=secretpassword

Usage

1. Set server.1.sasl.username and server.1.sasl.password in irc.conf
2. Restart the bot or use SITE RELOAD
3. Bot will now authenticate via SASL when connecting

Fixes: #57

[tsautier]

@mvangoor @hrxcodes for review