move capability handling code to a single file

irc/capability.go

@@ -0,0 +1,116 @@
+package irc
+
+import (
+	"strings"
+)
+
+type CapSubCommand string
+
+const (
+	CAP_LS    CapSubCommand = "LS"
+	CAP_LIST  CapSubCommand = "LIST"
+	CAP_REQ   CapSubCommand = "REQ"
+	CAP_ACK   CapSubCommand = "ACK"
+	CAP_NAK   CapSubCommand = "NAK"
+	CAP_CLEAR CapSubCommand = "CLEAR"
+	CAP_END   CapSubCommand = "END"
+)
+
+// Capabilities are optional features a client may request from a server.
+type Capability string
+
+const (
+	MultiPrefix Capability = "multi-prefix"
+	SASL        Capability = "sasl"
+)
+
+var (
+	SupportedCapabilities = CapabilitySet{
+		MultiPrefix: true,
+	}
+)
+
+func (capability Capability) String() string {
+	return string(capability)
+}
+
+// CapModifiers are indicators showing the state of a capability after a REQ or
+// ACK.
+type CapModifier rune
+
+const (
+	Ack     CapModifier = '~'
+	Disable CapModifier = '-'
+	Sticky  CapModifier = '='
+)
+
+func (mod CapModifier) String() string {
+	return string(mod)
+}
+
+type CapState uint
+
+const (
+	CapNone        CapState = iota
+	CapNegotiating CapState = iota
+	CapNegotiated  CapState = iota
+)
+
+type CapabilitySet map[Capability]bool
+
+func (set CapabilitySet) String() string {
+	strs := make([]string, len(set))
+	index := 0
+	for capability := range set {
+		strs[index] = string(capability)
+		index += 1
+	}
+	return strings.Join(strs, " ")
+}
+
+func (set CapabilitySet) DisableString() string {
+	parts := make([]string, len(set))
+	index := 0
+	for capability := range set {
+		parts[index] = Disable.String() + capability.String()
+		index += 1
+	}
+	return strings.Join(parts, " ")
+}
+
+func (msg *CapCommand) HandleRegServer(server *Server) {
+	client := msg.Client()
+
+	switch msg.subCommand {
+	case CAP_LS:
+		client.capState = CapNegotiating
+		client.Reply(RplCap(client, CAP_LS, SupportedCapabilities))
+
+	case CAP_LIST:
+		client.Reply(RplCap(client, CAP_LIST, client.capabilities))
+
+	case CAP_REQ:
+		for capability := range msg.capabilities {
+			if !SupportedCapabilities[capability] {
+				client.Reply(RplCap(client, CAP_NAK, msg.capabilities))
+				return
+			}
+		}
+		for capability := range msg.capabilities {
+			client.capabilities[capability] = true
+		}
+		client.Reply(RplCap(client, CAP_ACK, msg.capabilities))
+
+	case CAP_CLEAR:
+		reply := RplCap(client, CAP_ACK, client.capabilities.DisableString())
+		client.capabilities = make(CapabilitySet)
+		client.Reply(reply)
+
+	case CAP_END:
+		client.capState = CapNegotiated
+		server.tryRegister(client)
+
+	default:
+		client.ErrInvalidCapCmd(msg.subCommand)
+	}
+}