feat: add SMTP submission listener and enhance stalwart configuration (#425)

- add SMTP submission listener on port 587 with TLS requirement
- configure HAProxy frontend/backend for submission with send-proxy-v2 support
- add send-proxy-v2 support to all listeners
- add dynamic HAProxy node discovery for proxy trusted networks
- use service hostname instead of node FQDN for autoconfig/autodiscover
- remove redundant IMAP/IMAPS/SMTP alt-names from TLS certificates
- update VRRP CNAME configuration to use mail.main.unkin.net

Reviewed-on: #425

modules/stalwart/templates/config.toml.epp

@@ -2,7 +2,7 @@
 # Generated by Puppet - DO NOT EDIT MANUALLY
 
 [server]
-hostname = "<%= $node_facts['networking']['fqdn'] %>"
+hostname = "<%= $service_hostname %>"
 greeting = "Stalwart ESMTP"
 
 [server.listener."smtp-relay"]
@@ -10,10 +10,33 @@ bind = ["<%= $bind_address %>:25"]
 protocol = "smtp"
 greeting = "Stalwart SMTP Relay"
 
+<% if !$haproxy_ips.empty { -%>
+[server.listener."smtp-relay".proxy]
+trusted-networks = ["127.0.0.0/8", "::1"<% $haproxy_ips.each |$ip| { %>, "<%= $ip %>"<% } %>]
+<% } -%>
+
+<% if $enable_smtp_submission { -%>
+[server.listener."submission"]
+bind = ["<%= $bind_address %>:587"]
+protocol = "smtp"
+greeting = "Stalwart SMTP Submission"
+tls.require = true
+
+<% if !$haproxy_ips.empty { -%>
+[server.listener."submission".proxy]
+trusted-networks = ["127.0.0.0/8", "::1"<% $haproxy_ips.each |$ip| { %>, "<%= $ip %>"<% } %>]
+<% } -%>
+<% } -%>
+
 <% if $enable_imap { -%>
 [server.listener."imap"]
 bind = ["<%= $bind_address %>:143"]
 protocol = "imap"
+
+<% if !$haproxy_ips.empty { -%>
+[server.listener."imap".proxy]
+trusted-networks = ["127.0.0.0/8", "::1"<% $haproxy_ips.each |$ip| { %>, "<%= $ip %>"<% } %>]
+<% } -%>
 <% } -%>
 
 <% if $enable_imap_tls { -%>
@@ -21,6 +44,11 @@ protocol = "imap"
 bind = ["<%= $bind_address %>:993"]
 protocol = "imap"
 tls.implicit = true
+
+<% if !$haproxy_ips.empty { -%>
+[server.listener."imaps".proxy]
+trusted-networks = ["127.0.0.0/8", "::1"<% $haproxy_ips.each |$ip| { %>, "<%= $ip %>"<% } %>]
+<% } -%>
 <% } -%>
 
 <% if $enable_http { -%>
@@ -28,6 +56,11 @@ tls.implicit = true
 bind = ["<%= $bind_address %>:443"]
 protocol = "http"
 tls.implicit = true
+
+<% if !$haproxy_ips.empty { -%>
+[server.listener."https".proxy]
+trusted-networks = ["127.0.0.0/8", "::1"<% $haproxy_ips.each |$ip| { %>, "<%= $ip %>"<% } %>]
+<% } -%>
 <% } -%>
 
 [server.tls]
@@ -35,6 +68,7 @@ enable = true
 implicit = false
 certificate = "default"
 
+
 [webadmin]
 path = "<%= $webadmin_unpack_path %>"
 auto-update = <%= $webadmin_auto_update %>
@@ -167,6 +201,12 @@ directory = "internal"
 [imap.protocol]
 max-requests = 64
 
+# Inbound rate limiting
+[[queue.limiter.inbound]]
+key = ["remote_ip"]
+rate = "500/1s"
+enable = true
+
 # SMTP configuration for postfix relay
 [session.data]
 pipe.command = "sendmail"
@@ -212,6 +252,7 @@ max-message-size = 52428800
 [certificate."default"]
 cert = "%{file:<%= $tls_cert %>}%"
 private-key = "%{file:<%= $tls_key %>}%"
+default = true
 
 # Logging configuration
 [tracer]