NICK: Prevent races, remove a DoS

CHANGELOG.md

@@ -19,6 +19,8 @@ New release of Oragono!
 ### Removed
 
 ### Fixed
+* Prevented a DoS related to lots of clients connecting at once.
+* Removed races around setting and changing `NICK`s, to be more safe.
 * Fixed crash when using STATUSMSG-like messaging.
 * Fixed crash with gIRC-Go ircmsg library we depend on.
 

irc/client.go

@@ -14,8 +14,6 @@ import (
 	"strconv"
 	"time"
 
-	"strings"
-
 	"github.com/DanielOaks/girc-go/ircmsg"
 	"github.com/DanielOaks/go-ident"
 )
@@ -146,14 +144,12 @@ func (client *Client) run() {
 	client.rawHostname = AddrLookupHostname(client.socket.conn.RemoteAddr())
 
 	//TODO(dan): Make this a socketreactor from ircbnc
-	fmt.Println("START", &client)
 	for {
 		line, err = client.socket.Read()
 		if err != nil {
 			client.Quit("connection closed")
 			break
 		}
-		fmt.Println("  LINE", &client, strings.TrimSpace(line))
 
 		msg, err = ircmsg.ParseLine(line)
 		if err != nil {
@@ -163,7 +159,6 @@ func (client *Client) run() {
 
 		cmd, exists := Commands[msg.Command]
 		if !exists {
-			fmt.Println("    BADLINE", &client, strings.TrimSpace(line))
 			if len(msg.Command) > 0 {
 				client.Send(nil, client.server.name, ERR_UNKNOWNCOMMAND, client.nick, msg.Command, "Unknown command")
 			} else {
@@ -171,15 +166,11 @@ func (client *Client) run() {
 			}
 			continue
 		}
-		fmt.Println("    GUDLINE", &client, strings.TrimSpace(line))
 
 		isExiting = cmd.Run(client.server, client, msg)
-		fmt.Println("      CMDRUN", &client, strings.TrimSpace(line))
 		if isExiting || client.isQuitting {
-			fmt.Println("        BREAKING", &client, strings.TrimSpace(line))
 			break
 		}
-		fmt.Println("        CONTINUE", &client, strings.TrimSpace(line))
 	}
 
 	// ensure client connection gets closed
@@ -368,22 +359,22 @@ func (client *Client) SetNickname(nickname string) error {
 
 	client.nick = nickname
 	client.updateNick()
-	client.server.clients.Add(client)
-	return nil
+	return client.server.clients.Add(client)
 }
 
 // ChangeNickname changes the existing nickname of the client.
 func (client *Client) ChangeNickname(nickname string) error {
 	origNickMask := client.nickMaskString
-	client.server.clients.Remove(client)
+	client.updateNickMask()
+	err := client.server.clients.Replace(client.nick, nickname, client)
+	if err == nil {
 		client.server.whoWas.Append(client)
 		client.nick = nickname
-	client.updateNickMask()
-	client.server.clients.Add(client)
 		for friend := range client.Friends() {
 			friend.Send(nil, origNickMask, "NICK", nickname)
 		}
-	return nil
+	}
+	return err
 }
 
 func (client *Client) Quit(message string) {

irc/client_lookup_set.go

@@ -13,8 +13,6 @@ import (
 
 	"sync"
 
-	"runtime/debug"
-
 	"github.com/DanielOaks/girc-go/ircmatch"
 )
 
@@ -37,24 +35,8 @@ func ExpandUserHost(userhost string) (expanded string) {
 	return
 }
 
-type LoggingMutex struct {
-	mutex sync.Mutex
-}
-
-func (lm *LoggingMutex) Lock() {
-	lm.mutex.Lock()
-	fmt.Println("--- locked, stack:")
-	debug.PrintStack()
-}
-
-func (lm *LoggingMutex) Unlock() {
-	fmt.Println("--- unlocking")
-	lm.mutex.Unlock()
-	fmt.Println("--- unlocked")
-}
-
 type ClientLookupSet struct {
-	ByNickMutex LoggingMutex
+	ByNickMutex sync.Mutex
 	ByNick      map[string]*Client
 }
 
@@ -83,6 +65,7 @@ func (clients *ClientLookupSet) Has(nick string) bool {
 	return exists
 }
 
+// getNoMutex is used internally, for getting clients when no mutex is required (i.e. is already set).
 func (clients *ClientLookupSet) getNoMutex(nick string) *Client {
 	casefoldedName, err := CasefoldName(nick)
 	if err == nil {
@@ -104,23 +87,15 @@ func (clients *ClientLookupSet) Get(nick string) *Client {
 }
 
 func (clients *ClientLookupSet) Add(client *Client) error {
-	fmt.Println("Initial nick:", client.nick)
 	if !client.HasNick() {
 		return ErrNickMissing
 	}
-	fmt.Println("- getting lock:", client.nick)
 	clients.ByNickMutex.Lock()
-	fmt.Println("- got lock:", client.nick)
+	defer clients.ByNickMutex.Unlock()
 	if clients.getNoMutex(client.nick) != nil {
-		fmt.Println("- already exists:", client.nick)
-		clients.ByNickMutex.Unlock()
 		return ErrNicknameInUse
 	}
-	fmt.Println("- adding:", client.nick)
 	clients.ByNick[client.nickCasefolded] = client
-	fmt.Println("- set:", client.nick)
-	clients.ByNickMutex.Unlock()
-	fmt.Println("- released lock:", client.nick)
 	return nil
 }
 
@@ -128,15 +103,49 @@ func (clients *ClientLookupSet) Remove(client *Client) error {
 	if !client.HasNick() {
 		return ErrNickMissing
 	}
+	clients.ByNickMutex.Lock()
 	if clients.getNoMutex(client.nick) != client {
+		clients.ByNickMutex.Unlock()
 		return ErrNicknameMismatch
 	}
-	clients.ByNickMutex.Lock()
 	delete(clients.ByNick, client.nickCasefolded)
 	clients.ByNickMutex.Unlock()
 	return nil
 }
 
+func (clients *ClientLookupSet) Replace(oldNick, newNick string, client *Client) error {
+	// get casefolded nicknames
+	oldNick, err := CasefoldName(oldNick)
+	if err != nil {
+		return err
+	}
+	newNick, err = CasefoldName(newNick)
+	if err != nil {
+		return err
+	}
+
+	// remove and replace
+	clients.ByNickMutex.Lock()
+	defer clients.ByNickMutex.Unlock()
+
+	oldClient := clients.getNoMutex(newNick)
+	if oldClient != nil {
+		return ErrNicknameInUse
+	}
+	if oldClient != client {
+		return ErrNicknameMismatch
+	}
+
+	if oldNick == newNick {
+		// if they're only changing case, don't need to remove+re-add them
+		return nil
+	}
+
+	delete(clients.ByNick, oldNick)
+	clients.ByNick[newNick] = client
+	return nil
+}
+
 func (clients *ClientLookupSet) AllWithCaps(caps ...Capability) (set ClientSet) {
 	set = make(ClientSet)
 

irc/nickname.go

@@ -5,6 +5,7 @@
 package irc
 
 import (
+	"fmt"
 	"strings"
 
 	"github.com/DanielOaks/girc-go/ircmsg"
@@ -35,19 +36,17 @@ func nickHandler(server *Server, client *Client, msg ircmsg.IrcMessage) bool {
 	}
 
 	// bleh, this will be replaced and done below
-	target := server.clients.Get(nickname)
-	if target != nil && target != client {
-		client.Send(nil, server.name, ERR_NICKNAMEINUSE, client.nick, nicknameRaw, "Nickname is already in use")
-		return false
-	}
 	if client.registered {
 		err = client.ChangeNickname(nicknameRaw)
 	} else {
 		err = client.SetNickname(nicknameRaw)
 	}
-	if err != nil {
+	if err == ErrNicknameInUse {
 		client.Send(nil, server.name, ERR_NICKNAMEINUSE, client.nick, nicknameRaw, "Nickname is already in use")
 		return false
+	} else if err != nil {
+		client.Send(nil, server.name, ERR_UNKNOWNERROR, client.nick, "NICK", fmt.Sprintf("Could not set or change nickname: %s", err.Error()))
+		return false
 	}
 	if client.registered {
 		client.alertMonitors()

irc/server.go

@@ -567,7 +567,6 @@ func (server *Server) wslisten(addr string, tlsMap map[string]*TLSListenConfig)
 func (server *Server) tryRegister(c *Client) {
 	if c.registered || !c.HasNick() || !c.HasUsername() ||
 		(c.capState == CapNegotiating) {
-		fmt.Println("Try Reg:", &c, c.registered, c.HasNick(), c.HasUsername(), c.capState == CapNegotiating, c.capState)
 		return
 	}
 	c.Register()