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mirror of https://github.com/ergochat/ergo.git synced 2024-11-11 06:29:29 +01:00
ergo/irc/channel.go
Shivaram Lingamneni 60b861e07e fix a race in regenerateMembersCache
The rationale for why regenerateMembersCache didn't need to hold the Lock()
throughout was subtly wrong. It is true that at least some attempt to
regenerate the cache would see *all* the updates. However, it was possible for
the value of `result` generated by that attempt to lose the race for the final
assignment `channel.membersCache = result`.

The fix is to serialize the attempts to regenerate the cache, without adding
any additional locking on the underlying `Channel` fields via
`Channel.stateMutex`. This ensures that the final read from `Channel.members`
is paired with the final write to `Channel.membersCache`.
2017-11-07 14:38:18 -05:00

767 lines
22 KiB
Go

// Copyright (c) 2012-2014 Jeremy Latt
// Copyright (c) 2014-2015 Edmund Huber
// Copyright (c) 2016-2017 Daniel Oaks <daniel@danieloaks.net>
// released under the MIT license
package irc
import (
"fmt"
"strconv"
"time"
"sync"
"github.com/goshuirc/irc-go/ircmsg"
"github.com/oragono/oragono/irc/caps"
"github.com/tidwall/buntdb"
)
// Channel represents a channel that clients can join.
type Channel struct {
flags ModeSet
lists map[Mode]*UserMaskSet
key string
members MemberSet
membersCache []*Client // allow iteration over channel members without holding the lock
membersCacheMutex sync.Mutex // tier 2; see `regenerateMembersCache`
name string
nameCasefolded string
server *Server
createdTime time.Time
stateMutex sync.RWMutex
topic string
topicSetBy string
topicSetTime time.Time
userLimit uint64
}
// NewChannel creates a new channel from a `Server` and a `name`
// string, which must be unique on the server.
func NewChannel(s *Server, name string, addDefaultModes bool) *Channel {
casefoldedName, err := CasefoldChannel(name)
if err != nil {
s.logger.Error("internal", fmt.Sprintf("Bad channel name %s: %v", name, err))
return nil
}
channel := &Channel{
flags: make(ModeSet),
lists: map[Mode]*UserMaskSet{
BanMask: NewUserMaskSet(),
ExceptMask: NewUserMaskSet(),
InviteMask: NewUserMaskSet(),
},
members: make(MemberSet),
name: name,
nameCasefolded: casefoldedName,
server: s,
}
if addDefaultModes {
for _, mode := range s.DefaultChannelModes() {
channel.flags[mode] = true
}
}
return channel
}
func (channel *Channel) regenerateMembersCache() {
// this is eventually consistent even without holding stateMutex.Lock()
// throughout the update; all updates to `members` while holding Lock()
// have a serial order, so the call to `regenerateMembersCache` that
// happens-after the last one will see *all* the updates. then,
// `membersCacheMutex` ensures that this final read is correctly paired
// with the final write to `membersCache`.
channel.membersCacheMutex.Lock()
defer channel.membersCacheMutex.Unlock()
channel.stateMutex.RLock()
result := make([]*Client, len(channel.members))
i := 0
for client := range channel.members {
result[i] = client
i++
}
channel.stateMutex.RUnlock()
channel.stateMutex.Lock()
channel.membersCache = result
channel.stateMutex.Unlock()
return
}
// Names sends the list of users joined to the channel to the given client.
func (channel *Channel) Names(client *Client) {
currentNicks := channel.nicks(client)
// assemble and send replies
maxNamLen := 480 - len(client.server.name) - len(client.nick)
var buffer string
for _, nick := range currentNicks {
if buffer == "" {
buffer += nick
continue
}
if len(buffer)+1+len(nick) > maxNamLen {
client.Send(nil, client.server.name, RPL_NAMREPLY, client.nick, "=", channel.name, buffer)
buffer = nick
continue
}
buffer += " "
buffer += nick
}
client.Send(nil, client.server.name, RPL_NAMREPLY, client.nick, "=", channel.name, buffer)
client.Send(nil, client.server.name, RPL_ENDOFNAMES, client.nick, channel.name, "End of NAMES list")
}
// ClientIsAtLeast returns whether the client has at least the given channel privilege.
func (channel *Channel) ClientIsAtLeast(client *Client, permission Mode) bool {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
// get voice, since it's not a part of ChannelPrivModes
if channel.members.HasMode(client, permission) {
return true
}
// check regular modes
for _, mode := range ChannelPrivModes {
if channel.members.HasMode(client, mode) {
return true
}
if mode == permission {
break
}
}
return false
}
// Prefixes returns a list of prefixes for the given set of channel modes.
func (modes ModeSet) Prefixes(isMultiPrefix bool) string {
var prefixes string
// add prefixes in order from highest to lowest privs
for _, mode := range ChannelPrivModes {
if modes[mode] {
prefixes += ChannelModePrefixes[mode]
}
}
if modes[Voice] {
prefixes += ChannelModePrefixes[Voice]
}
if !isMultiPrefix && len(prefixes) > 1 {
prefixes = string(prefixes[0])
}
return prefixes
}
func (channel *Channel) ClientPrefixes(client *Client, isMultiPrefix bool) string {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
modes, present := channel.members[client]
if !present {
return ""
} else {
return modes.Prefixes(isMultiPrefix)
}
}
func (channel *Channel) ClientHasPrivsOver(client *Client, target *Client) bool {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
clientModes := channel.members[client]
targetModes := channel.members[target]
result := false
for _, mode := range ChannelPrivModes {
if clientModes[mode] {
result = true
// admins cannot kick other admins
if mode == ChannelAdmin && targetModes[ChannelAdmin] {
result = false
}
break
} else if channel.members[target][mode] {
break
}
}
return result
}
func (channel *Channel) nicks(target *Client) []string {
isMultiPrefix := (target != nil) && target.capabilities.Has(caps.MultiPrefix)
isUserhostInNames := (target != nil) && target.capabilities.Has(caps.UserhostInNames)
// slightly cumbersome: get the mutex and copy both the client pointers and
// the mode prefixes
channel.stateMutex.RLock()
length := len(channel.members)
clients := make([]*Client, length)
result := make([]string, length)
i := 0
for client, modes := range channel.members {
clients[i] = client
result[i] = modes.Prefixes(isMultiPrefix)
i++
}
channel.stateMutex.RUnlock()
i = 0
for i < length {
if isUserhostInNames {
result[i] += clients[i].NickMaskString()
} else {
result[i] += clients[i].Nick()
}
i++
}
return result
}
func (channel *Channel) hasClient(client *Client) bool {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
_, present := channel.members[client]
return present
}
// <mode> <mode params>
func (channel *Channel) modeStrings(client *Client) (result []string) {
isMember := client.HasMode(Operator) || channel.hasClient(client)
showKey := isMember && (channel.key != "")
showUserLimit := channel.userLimit > 0
modes := "+"
// flags with args
if showKey {
modes += Key.String()
}
if showUserLimit {
modes += UserLimit.String()
}
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
// flags
for mode := range channel.flags {
modes += mode.String()
}
result = []string{modes}
// args for flags with args: The order must match above to keep
// positional arguments in place.
if showKey {
result = append(result, channel.key)
}
if showUserLimit {
result = append(result, strconv.FormatUint(channel.userLimit, 10))
}
return
}
// IsFull returns true if this channel is at its' members limit.
func (channel *Channel) IsFull() bool {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
return (channel.userLimit > 0) && (uint64(len(channel.members)) >= channel.userLimit)
}
// CheckKey returns true if the key is not set or matches the given key.
func (channel *Channel) CheckKey(key string) bool {
return (channel.key == "") || (channel.key == key)
}
func (channel *Channel) IsEmpty() bool {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
return len(channel.members) == 0
}
// Join joins the given client to this channel (if they can be joined).
//TODO(dan): /SAJOIN and maybe a ForceJoin function?
func (channel *Channel) Join(client *Client, key string) {
if channel.hasClient(client) {
// already joined, no message needs to be sent
return
}
if channel.IsFull() {
client.Send(nil, client.server.name, ERR_CHANNELISFULL, channel.name, "Cannot join channel (+l)")
return
}
if !channel.CheckKey(key) {
client.Send(nil, client.server.name, ERR_BADCHANNELKEY, channel.name, "Cannot join channel (+k)")
return
}
isInvited := channel.lists[InviteMask].Match(client.nickMaskCasefolded)
if channel.flags[InviteOnly] && !isInvited {
client.Send(nil, client.server.name, ERR_INVITEONLYCHAN, channel.name, "Cannot join channel (+i)")
return
}
if channel.lists[BanMask].Match(client.nickMaskCasefolded) &&
!isInvited &&
!channel.lists[ExceptMask].Match(client.nickMaskCasefolded) {
client.Send(nil, client.server.name, ERR_BANNEDFROMCHAN, channel.name, "Cannot join channel (+b)")
return
}
client.server.logger.Debug("join", fmt.Sprintf("%s joined channel %s", client.nick, channel.name))
for _, member := range channel.Members() {
if member.capabilities.Has(caps.ExtendedJoin) {
member.Send(nil, client.nickMaskString, "JOIN", channel.name, client.account.Name, client.realname)
} else {
member.Send(nil, client.nickMaskString, "JOIN", channel.name)
}
}
channel.stateMutex.Lock()
channel.members.Add(client)
firstJoin := len(channel.members) == 1
channel.stateMutex.Unlock()
channel.regenerateMembersCache()
client.addChannel(channel)
// give channel mode if necessary
var newChannel bool
var givenMode *Mode
client.server.registeredChannelsMutex.Lock()
defer client.server.registeredChannelsMutex.Unlock()
client.server.store.Update(func(tx *buntdb.Tx) error {
chanReg := client.server.loadChannelNoMutex(tx, channel.nameCasefolded)
if chanReg == nil {
if firstJoin {
channel.stateMutex.Lock()
channel.createdTime = time.Now()
channel.members[client][ChannelOperator] = true
channel.stateMutex.Unlock()
givenMode = &ChannelOperator
newChannel = true
}
} else {
// we should only do this on registered channels
if client.account != nil && client.account.Name == chanReg.Founder {
channel.stateMutex.Lock()
channel.members[client][ChannelFounder] = true
channel.stateMutex.Unlock()
givenMode = &ChannelFounder
}
if firstJoin {
// apply other details if new channel
channel.stateMutex.Lock()
channel.topic = chanReg.Topic
channel.topicSetBy = chanReg.TopicSetBy
channel.topicSetTime = chanReg.TopicSetTime
channel.name = chanReg.Name
channel.createdTime = chanReg.RegisteredAt
for _, mask := range chanReg.Banlist {
channel.lists[BanMask].Add(mask)
}
for _, mask := range chanReg.Exceptlist {
channel.lists[ExceptMask].Add(mask)
}
for _, mask := range chanReg.Invitelist {
channel.lists[InviteMask].Add(mask)
}
channel.stateMutex.Unlock()
}
}
return nil
})
if client.capabilities.Has(caps.ExtendedJoin) {
client.Send(nil, client.nickMaskString, "JOIN", channel.name, client.account.Name, client.realname)
} else {
client.Send(nil, client.nickMaskString, "JOIN", channel.name)
}
// don't sent topic when it's an entirely new channel
if !newChannel {
channel.SendTopic(client)
}
channel.Names(client)
if givenMode != nil {
for _, member := range channel.Members() {
member.Send(nil, client.server.name, "MODE", channel.name, fmt.Sprintf("+%v", *givenMode), client.nick)
}
}
}
// Part parts the given client from this channel, with the given message.
func (channel *Channel) Part(client *Client, message string) {
if !channel.hasClient(client) {
client.Send(nil, client.server.name, ERR_NOTONCHANNEL, channel.name, "You're not on that channel")
return
}
for _, member := range channel.Members() {
member.Send(nil, client.nickMaskString, "PART", channel.name, message)
}
channel.Quit(client)
client.server.logger.Debug("part", fmt.Sprintf("%s left channel %s", client.nick, channel.name))
}
// SendTopic sends the channel topic to the given client.
func (channel *Channel) SendTopic(client *Client) {
if !channel.hasClient(client) {
client.Send(nil, client.server.name, ERR_NOTONCHANNEL, client.nick, channel.name, "You're not on that channel")
return
}
channel.stateMutex.RLock()
name := channel.name
topic := channel.topic
topicSetBy := channel.topicSetBy
topicSetTime := channel.topicSetTime
channel.stateMutex.RUnlock()
if topic == "" {
client.Send(nil, client.server.name, RPL_NOTOPIC, client.nick, name, "No topic is set")
return
}
client.Send(nil, client.server.name, RPL_TOPIC, client.nick, name, topic)
client.Send(nil, client.server.name, RPL_TOPICTIME, client.nick, name, topicSetBy, strconv.FormatInt(topicSetTime.Unix(), 10))
}
// SetTopic sets the topic of this channel, if the client is allowed to do so.
func (channel *Channel) SetTopic(client *Client, topic string) {
if !(client.flags[Operator] || channel.hasClient(client)) {
client.Send(nil, client.server.name, ERR_NOTONCHANNEL, channel.name, "You're not on that channel")
return
}
if channel.HasMode(OpOnlyTopic) && !channel.ClientIsAtLeast(client, ChannelOperator) {
client.Send(nil, client.server.name, ERR_CHANOPRIVSNEEDED, channel.name, "You're not a channel operator")
return
}
if len(topic) > client.server.limits.TopicLen {
topic = topic[:client.server.limits.TopicLen]
}
channel.stateMutex.Lock()
channel.topic = topic
channel.topicSetBy = client.nickMaskString
channel.topicSetTime = time.Now()
channel.stateMutex.Unlock()
for _, member := range channel.Members() {
member.Send(nil, client.nickMaskString, "TOPIC", channel.name, topic)
}
// update saved channel topic for registered chans
client.server.registeredChannelsMutex.Lock()
defer client.server.registeredChannelsMutex.Unlock()
client.server.store.Update(func(tx *buntdb.Tx) error {
chanInfo := client.server.loadChannelNoMutex(tx, channel.nameCasefolded)
if chanInfo == nil {
return nil
}
chanInfo.Topic = topic
chanInfo.TopicSetBy = client.nickMaskString
chanInfo.TopicSetTime = time.Now()
client.server.saveChannelNoMutex(tx, channel.nameCasefolded, *chanInfo)
return nil
})
}
// CanSpeak returns true if the client can speak on this channel.
func (channel *Channel) CanSpeak(client *Client) bool {
channel.stateMutex.RLock()
defer channel.stateMutex.RUnlock()
_, hasClient := channel.members[client]
if channel.flags[NoOutside] && !hasClient {
return false
}
if channel.flags[Moderated] && !channel.ClientIsAtLeast(client, Voice) {
return false
}
if channel.flags[RegisteredOnly] && client.account == &NoAccount {
return false
}
return true
}
// TagMsg sends a tag message to everyone in this channel who can accept them.
func (channel *Channel) TagMsg(msgid string, minPrefix *Mode, clientOnlyTags *map[string]ircmsg.TagValue, client *Client) {
channel.sendMessage(msgid, "TAGMSG", []caps.Capability{caps.MessageTags}, minPrefix, clientOnlyTags, client, nil)
}
// sendMessage sends a given message to everyone on this channel.
func (channel *Channel) sendMessage(msgid, cmd string, requiredCaps []caps.Capability, minPrefix *Mode, clientOnlyTags *map[string]ircmsg.TagValue, client *Client, message *string) {
if !channel.CanSpeak(client) {
client.Send(nil, client.server.name, ERR_CANNOTSENDTOCHAN, channel.name, "Cannot send to channel")
return
}
// for STATUSMSG
var minPrefixMode Mode
if minPrefix != nil {
minPrefixMode = *minPrefix
}
for _, member := range channel.Members() {
if minPrefix != nil && !channel.ClientIsAtLeast(member, minPrefixMode) {
// STATUSMSG
continue
}
if member == client && !client.capabilities.Has(caps.EchoMessage) {
continue
}
canReceive := true
for _, capName := range requiredCaps {
if !member.capabilities.Has(capName) {
canReceive = false
}
}
if !canReceive {
continue
}
var messageTagsToUse *map[string]ircmsg.TagValue
if member.capabilities.Has(caps.MessageTags) {
messageTagsToUse = clientOnlyTags
}
if message == nil {
member.SendFromClient(msgid, client, messageTagsToUse, cmd, channel.name)
} else {
member.SendFromClient(msgid, client, messageTagsToUse, cmd, channel.name, *message)
}
}
}
// SplitPrivMsg sends a private message to everyone in this channel.
func (channel *Channel) SplitPrivMsg(msgid string, minPrefix *Mode, clientOnlyTags *map[string]ircmsg.TagValue, client *Client, message SplitMessage) {
channel.sendSplitMessage(msgid, "PRIVMSG", minPrefix, clientOnlyTags, client, &message)
}
// SplitNotice sends a private message to everyone in this channel.
func (channel *Channel) SplitNotice(msgid string, minPrefix *Mode, clientOnlyTags *map[string]ircmsg.TagValue, client *Client, message SplitMessage) {
channel.sendSplitMessage(msgid, "NOTICE", minPrefix, clientOnlyTags, client, &message)
}
func (channel *Channel) sendSplitMessage(msgid, cmd string, minPrefix *Mode, clientOnlyTags *map[string]ircmsg.TagValue, client *Client, message *SplitMessage) {
if !channel.CanSpeak(client) {
client.Send(nil, client.server.name, ERR_CANNOTSENDTOCHAN, channel.name, "Cannot send to channel")
return
}
// for STATUSMSG
var minPrefixMode Mode
if minPrefix != nil {
minPrefixMode = *minPrefix
}
for _, member := range channel.Members() {
if minPrefix != nil && !channel.ClientIsAtLeast(member, minPrefixMode) {
// STATUSMSG
continue
}
if member == client && !client.capabilities.Has(caps.EchoMessage) {
continue
}
var tagsToUse *map[string]ircmsg.TagValue
if member.capabilities.Has(caps.MessageTags) {
tagsToUse = clientOnlyTags
}
if message == nil {
member.SendFromClient(msgid, client, tagsToUse, cmd, channel.name)
} else {
member.SendSplitMsgFromClient(msgid, client, tagsToUse, cmd, channel.name, *message)
}
}
}
func (channel *Channel) applyModeMemberNoMutex(client *Client, mode Mode,
op ModeOp, nick string) *ModeChange {
if nick == "" {
//TODO(dan): shouldn't this be handled before it reaches this function?
client.Send(nil, client.server.name, ERR_NEEDMOREPARAMS, "MODE", "Not enough parameters")
return nil
}
casefoldedName, err := CasefoldName(nick)
target := channel.server.clients.Get(casefoldedName)
if err != nil || target == nil {
client.Send(nil, client.server.name, ERR_NOSUCHNICK, client.nick, nick, "No such nick")
return nil
}
channel.stateMutex.Lock()
modeset, exists := channel.members[target]
var already bool
if exists {
enable := op == Add
already = modeset[mode] == enable
modeset[mode] = enable
}
channel.stateMutex.Unlock()
if !exists {
client.Send(nil, client.server.name, ERR_USERNOTINCHANNEL, client.nick, channel.name, "They aren't on that channel")
return nil
} else if already {
return nil
} else {
return &ModeChange{
op: op,
mode: mode,
arg: nick,
}
}
}
// ShowMaskList shows the given list to the client.
func (channel *Channel) ShowMaskList(client *Client, mode Mode) {
// choose appropriate modes
var rpllist, rplendoflist string
if mode == BanMask {
rpllist = RPL_BANLIST
rplendoflist = RPL_ENDOFBANLIST
} else if mode == ExceptMask {
rpllist = RPL_EXCEPTLIST
rplendoflist = RPL_ENDOFEXCEPTLIST
} else if mode == InviteMask {
rpllist = RPL_INVITELIST
rplendoflist = RPL_ENDOFINVITELIST
}
nick := client.Nick()
channel.stateMutex.RLock()
// XXX don't acquire any new locks in this section, besides Socket.Write
for mask := range channel.lists[mode].masks {
client.Send(nil, client.server.name, rpllist, nick, channel.name, mask)
}
channel.stateMutex.RUnlock()
client.Send(nil, client.server.name, rplendoflist, nick, channel.name, "End of list")
}
func (channel *Channel) applyModeMask(client *Client, mode Mode, op ModeOp, mask string) bool {
list := channel.lists[mode]
if list == nil {
// This should never happen, but better safe than panicky.
return false
}
if (op == List) || (mask == "") {
channel.ShowMaskList(client, mode)
return false
}
if !channel.ClientIsAtLeast(client, ChannelOperator) {
client.Send(nil, client.server.name, ERR_CHANOPRIVSNEEDED, channel.name, "You're not a channel operator")
return false
}
if op == Add {
return list.Add(mask)
}
if op == Remove {
return list.Remove(mask)
}
return false
}
// Quit removes the given client from the channel
func (channel *Channel) Quit(client *Client) {
channel.stateMutex.Lock()
channel.members.Remove(client)
channel.stateMutex.Unlock()
channel.regenerateMembersCache()
client.removeChannel(channel)
}
func (channel *Channel) Kick(client *Client, target *Client, comment string) {
if !(client.flags[Operator] || channel.hasClient(client)) {
client.Send(nil, client.server.name, ERR_NOTONCHANNEL, channel.name, "You're not on that channel")
return
}
if !channel.ClientIsAtLeast(client, ChannelOperator) {
client.Send(nil, client.server.name, ERR_CANNOTSENDTOCHAN, channel.name, "Cannot send to channel")
return
}
if !channel.hasClient(target) {
client.Send(nil, client.server.name, ERR_USERNOTINCHANNEL, client.nick, channel.name, "They aren't on that channel")
return
}
if !channel.ClientHasPrivsOver(client, target) {
client.Send(nil, client.server.name, ERR_CHANOPRIVSNEEDED, channel.name, "You're not a channel operator")
return
}
kicklimit := client.server.Limits().KickLen
if len(comment) > kicklimit {
comment = comment[:kicklimit]
}
clientMask := client.NickMaskString()
targetNick := target.Nick()
for _, member := range channel.Members() {
member.Send(nil, clientMask, "KICK", channel.name, targetNick, comment)
}
channel.Quit(target)
}
// Invite invites the given client to the channel, if the inviter can do so.
func (channel *Channel) Invite(invitee *Client, inviter *Client) {
if channel.flags[InviteOnly] && !channel.ClientIsAtLeast(inviter, ChannelOperator) {
inviter.Send(nil, inviter.server.name, ERR_CHANOPRIVSNEEDED, channel.name, "You're not a channel operator")
return
}
if !channel.hasClient(inviter) {
inviter.Send(nil, inviter.server.name, ERR_NOTONCHANNEL, channel.name, "You're not on that channel")
return
}
//TODO(dan): handle this more nicely, keep a list of last X invited channels on invitee rather than explicitly modifying the invite list?
if channel.flags[InviteOnly] {
nmc := invitee.NickCasefolded()
channel.stateMutex.Lock()
channel.lists[InviteMask].Add(nmc)
channel.stateMutex.Unlock()
}
for _, member := range channel.Members() {
if member.capabilities.Has(caps.InviteNotify) && member != inviter && member != invitee && channel.ClientIsAtLeast(member, Halfop) {
member.Send(nil, inviter.NickMaskString(), "INVITE", invitee.Nick(), channel.name)
}
}
//TODO(dan): should inviter.server.name here be inviter.nickMaskString ?
inviter.Send(nil, inviter.server.name, RPL_INVITING, invitee.nick, channel.name)
invitee.Send(nil, inviter.nickMaskString, "INVITE", invitee.nick, channel.name)
if invitee.flags[Away] {
inviter.Send(nil, inviter.server.name, RPL_AWAY, invitee.nick, invitee.awayMessage)
}
}