restore PROXY protocol support

support for PROXY was removed in 43e28e2fef. After discussion,
it's worth keeping around in case of client compatibility issues,
and until /rehash support is more mature.

irc/client.go

@@ -66,6 +66,7 @@ type Client struct {
 	nickMaskCasefolded string
 	nickMaskString     string // cache for nickmask string since it's used with lots of replies
 	operName           string
+	proxiedIP          string // actual remote IP if using the PROXY protocol
 	quitMessageSent    bool
 	quitMutex          sync.Mutex
 	quitTimer          *time.Timer
@@ -147,11 +148,19 @@ func NewClient(server *Server, conn net.Conn, isTLS bool) *Client {
 
 // IP returns the IP address of this client.
 func (client *Client) IP() net.IP {
+	if client.proxiedIP != "" {
+		return net.ParseIP(client.proxiedIP)
+	}
+
 	return net.ParseIP(IPString(client.socket.conn.RemoteAddr()))
 }
 
 // IPString returns the IP address of this client as a string.
 func (client *Client) IPString() string {
+	if client.proxiedIP != "" {
+		return client.proxiedIP
+	}
+
 	ip := client.IP().String()
 	if 0 < len(ip) && ip[0] == ':' {
 		ip = "0" + ip
@@ -185,6 +194,7 @@ func (client *Client) run() {
 	var msg ircmsg.IrcMessage
 
 	// Set the hostname for this client
+	// (may be overridden by a later PROXY command from stunnel)
 	client.rawHostname = AddrLookupHostname(client.socket.conn.RemoteAddr())
 
 	for {

irc/commands.go

@@ -207,6 +207,11 @@ var Commands = map[string]Command{
 		handler:   privmsgHandler,
 		minParams: 2,
 	},
+	"PROXY": {
+		handler:      proxyHandler,
+		usablePreReg: true,
+		minParams:    5,
+	},
 	"RENAME": {
 		handler:   renameHandler,
 		minParams: 2,

irc/config.go

@@ -202,6 +202,7 @@ type Config struct {
 		RestAPI            RestAPIConfig `yaml:"rest-api"`
 		CheckIdent         bool          `yaml:"check-ident"`
 		MOTD               string
+		ProxyAllowedFrom   []string `yaml:"proxy-allowed-from"`
 		MaxSendQString     string   `yaml:"max-sendq"`
 		MaxSendQBytes      uint64
 		ConnectionLimits   ConnectionLimitsConfig   `yaml:"connection-limits"`

irc/help.go

@@ -356,6 +356,13 @@ Replies to a PING. Used to check link connectivity.`,
 		text: `PRIVMSG <target>{,<target>} <text to be sent>
 
 Sends the text to the given targets as a PRIVMSG.`,
+	},
+	"proxy": {
+		oper: true, // not really, but it's restricted anyways
+		text: `PROXY TCP4/6 <sourceip> <destip> <sourceport> <destport>
+
+Used by haproxy's PROXY protocol, to allow for alternate TLS support:
+http://www.haproxy.org/download/1.7/doc/proxy-protocol.txt`,
 	},
 	"rename": {
 		text: `RENAME <channel> <newname> [<reason>]

irc/server.go

@@ -109,6 +109,7 @@ type Server struct {
 	rehashMutex                  sync.Mutex
 	rehashSignal                 chan os.Signal
 	restAPI                      *RestAPIConfig
+	proxyAllowedFrom             []string
 	signals                      chan os.Signal
 	snomasks                     *SnoManager
 	store                        *buntdb.DB
@@ -217,6 +218,7 @@ func NewServer(configFilename string, config *Config, logger *logger.Manager) (*
 		newConns:           make(chan clientConn),
 		operators:          opers,
 		operclasses:        *operClasses,
+		proxyAllowedFrom:   config.Server.ProxyAllowedFrom,
 		registeredChannels: make(map[string]*RegisteredChannel),
 		rehashSignal:       make(chan os.Signal, 1),
 		restAPI:            &config.Server.RestAPI,
@@ -2224,3 +2226,19 @@ func userhostHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool
 
 	return false
 }
+
+// PROXY TCP4/6 SOURCEIP DESTIP SOURCEPORT DESTPORT
+// http://www.haproxy.org/download/1.5/doc/proxy-protocol.txt
+func proxyHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
+	clientAddress := IPString(client.socket.conn.RemoteAddr())
+	clientHostname := client.hostname
+	for _, address := range server.proxyAllowedFrom {
+		if clientHostname == address || clientAddress == address {
+			client.proxiedIP = msg.Params[1]
+			client.hostname = LookupHostname(msg.Params[1])
+			return false
+		}
+	}
+	client.Quit("PROXY command is not usable from your address")
+	return true
+}

oragono.yaml

@@ -65,6 +65,10 @@ server:
     # if you change the motd, you should move it to ircd.motd
     motd: oragono.motd
 
+    # addresses/hostnames the PROXY command can be used from
+    # this should be restricted to 127.0.0.1 and localhost at most
+    proxy-allowed-from: []
+
     # maximum length of clients' sendQ in bytes
     # this should be big enough to hold /LIST and HELP replies
     max-sendq: 16k