server: Add away-notify capability

irc/capability.go

@@ -15,6 +15,7 @@ type Capability string
 
 const (
 	AccountTag      Capability = "account-tag"
+	AwayNotify      Capability = "away-notify"
 	ExtendedJoin    Capability = "extended-join"
 	MultiPrefix     Capability = "multi-prefix"
 	SASL            Capability = "sasl"
@@ -25,6 +26,7 @@ const (
 var (
 	SupportedCapabilities = CapabilitySet{
 		AccountTag:      true,
+		AwayNotify:      true,
 		ExtendedJoin:    true,
 		MultiPrefix:     true,
 		SASL:            true,

irc/server.go

@@ -830,6 +830,16 @@ func awayHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
 		op:   op,
 	}}
 	client.Send(nil, server.nameString, "MODE", client.nickString, client.nickString, modech.String())
+
+	// dispatch away-notify
+	for friend := range client.Friends() {
+		if client.flags[Away] {
+			friend.SendFromClient(client, nil, client.nickMaskString, "AWAY", client.awayMessage)
+		} else {
+			friend.SendFromClient(client, nil, client.nickMaskString, "AWAY")
+		}
+	}
+
 	return false
 }