add WebIRC support; closes lrstanley#33 and lrstanley#34

README.md

@@ -88,6 +88,8 @@ girc artwork licensed under [CC 3.0](http://creativecommons.org/licenses/by/3.0/
    * [IRCv3: Specification Docs](http://ircv3.net/irc/)
    * [IRCv3: Specification Repo](https://github.com/ircv3/ircv3-specifications)
    * [IRCv3 Capability Registry](http://ircv3.net/registry.html)
+   * [IRCv3: WEBIRC](https://ircv3.net/specs/extensions/webirc.html)
+   * [KiwiIRC: WEBIRC](https://kiwiirc.com/docs/webirc)
    * [ISUPPORT Specification Docs](http://www.irc.org/tech_docs/005.html) ([alternative 1](http://defs.ircdocs.horse/defs/isupport.html), [alternative 2](https://github.com/grawity/irc-docs/blob/master/client/RPL_ISUPPORT/draft-hardy-irc-isupport-00.txt), [relevant draft](http://www.irc.org/tech_docs/draft-brocklesby-irc-isupport-03.txt))
    * [IRC Numerics List](http://defs.ircdocs.horse/defs/numerics.html)
    * [Extended WHO (also known as WHOX)](https://github.com/quakenet/snircd/blob/master/doc/readme.who)

client.go

@@ -81,6 +81,10 @@ type Config struct {
 	// supported. Capability tracking must be enabled for this to work, as
 	// this requires IRCv3 CAP handling.
 	SASL SASLMech
+	// WebIRC allows forwarding source user hostname/ip information to the server
+	// (if supported by the server) to ensure the source machine doesn't show as
+	// the source. See the WebIRC type for more information.
+	WebIRC WebIRC
 	// Bind is used to bind to a specific host or ip during the dial process
 	// when connecting to the server. This can be a hostname, however it must
 	// resolve to an IPv4/IPv6 address bindable on your system. Otherwise,
@@ -154,6 +158,39 @@ type Config struct {
 	HandleNickCollide func(oldNick string) (newNick string)
 }
 
+// WebIRC is useful when a user connects through an indirect method, such web
+// clients, the indirect client sends its own IP address instead of sending the
+// user's IP address unless WebIRC is implemented by both the client and the
+// server.
+//
+// Client expectations:
+//  - Perform any proxy resolution.
+//  - Check the reverse DNS and forward DNS match.
+//  - Check the IP against suitable access controls (ipaccess, dnsbl, etc).
+//
+// More information:
+//  - https://ircv3.net/specs/extensions/webirc.html
+//  - https://kiwiirc.com/docs/webirc
+type WebIRC struct {
+	// Password that authenticates the WEBIRC command from this client.
+	Password string
+	// Gateway or client type requesting spoof (cgiirc defaults to cgiirc, as an
+	// example).
+	Gateway string
+	// Hostname of user.
+	Hostname string
+	// Address either in IPv4 dotted quad notation (e.g. 192.0.0.2) or IPv6
+	// notation (e.g. 1234:5678:9abc::def). IPv4-in-IPv6 addresses
+	// (e.g. ::ffff:192.0.0.2) should not be sent.
+	Address string
+}
+
+// Params returns the arguments for the WEBIRC command that can be passed to the
+// server.
+func (w WebIRC) Params() []string {
+	return []string{w.Password, w.Gateway, w.Hostname, w.Address}
+}
+
 // ErrInvalidConfig is returned when the configuration passed to the client
 // is invalid.
 type ErrInvalidConfig struct {

conn.go

@@ -284,6 +284,11 @@ func (c *Client) internalConnect(mock net.Conn, dialer Dialer) error {
 	go c.pingLoop(ctx, errs, &wg)
 
 	// Passwords first.
+
+	if c.Config.WebIRC.Password != "" {
+		c.write(&Event{Command: WEBIRC, Params: c.Config.WebIRC.Params(), Sensitive: true})
+	}
+
 	if c.Config.ServerPass != "" {
 		c.write(&Event{Command: PASS, Params: []string{c.Config.ServerPass}, Sensitive: true})
 	}

constants.go

@@ -118,6 +118,7 @@ const (
 	USERS    = "USERS"
 	VERSION  = "VERSION"
 	WALLOPS  = "WALLOPS"
+	WEBIRC   = "WEBIRC"
 	WHO      = "WHO"
 	WHOIS    = "WHOIS"
 	WHOWAS   = "WHOWAS"