source: code/trunk/irc.go@ 468

package soju

import (
        "fmt"
        "sort"
        "strings"

        "gopkg.in/irc.v3"
)

const (
        rpl_statsping     = "246"
        rpl_localusers    = "265"
        rpl_globalusers   = "266"
        rpl_creationtime  = "329"
        rpl_topicwhotime  = "333"
        err_invalidcapcmd = "410"
)

const (
        maxMessageLength = 512
        maxMessageParams = 15
)

// The server-time layout, as defined in the IRCv3 spec.
const serverTimeLayout = "2006-01-02T15:04:05.000Z"

type userModes string

func (ms userModes) Has(c byte) bool {
        return strings.IndexByte(string(ms), c) >= 0
}

func (ms *userModes) Add(c byte) {
        if !ms.Has(c) {
                *ms += userModes(c)
        }
}

func (ms *userModes) Del(c byte) {
        i := strings.IndexByte(string(*ms), c)
        if i >= 0 {
                *ms = (*ms)[:i] + (*ms)[i+1:]
        }
}

func (ms *userModes) Apply(s string) error {
        var plusMinus byte
        for i := 0; i < len(s); i++ {
                switch c := s[i]; c {
                case '+', '-':
                        plusMinus = c
                default:
                        switch plusMinus {
                        case '+':
                                ms.Add(c)
                        case '-':
                                ms.Del(c)
                        default:
                                return fmt.Errorf("malformed modestring %q: missing plus/minus", s)
                        }
                }
        }
        return nil
}

type channelModeType byte

// standard channel mode types, as explained in https://modern.ircdocs.horse/#mode-message
const (
        // modes that add or remove an address to or from a list
        modeTypeA channelModeType = iota
        // modes that change a setting on a channel, and must always have a parameter
        modeTypeB
        // modes that change a setting on a channel, and must have a parameter when being set, and no parameter when being unset
        modeTypeC
        // modes that change a setting on a channel, and must not have a parameter
        modeTypeD
)

var stdChannelModes = map[byte]channelModeType{
        'b': modeTypeA, // ban list
        'e': modeTypeA, // ban exception list
        'I': modeTypeA, // invite exception list
        'k': modeTypeB, // channel key
        'l': modeTypeC, // channel user limit
        'i': modeTypeD, // channel is invite-only
        'm': modeTypeD, // channel is moderated
        'n': modeTypeD, // channel has no external messages
        's': modeTypeD, // channel is secret
        't': modeTypeD, // channel has protected topic
}

type channelModes map[byte]string

// applyChannelModes parses a mode string and mode arguments from a MODE message,
// and applies the corresponding channel mode and user membership changes on that channel.
//
// If ch.modes is nil, channel modes are not updated.
//
// needMarshaling is a list of indexes of mode arguments that represent entities
// that must be marshaled when sent downstream.
func applyChannelModes(ch *upstreamChannel, modeStr string, arguments []string) (needMarshaling map[int]struct{}, err error) {
        needMarshaling = make(map[int]struct{}, len(arguments))
        nextArgument := 0
        var plusMinus byte
outer:
        for i := 0; i < len(modeStr); i++ {
                mode := modeStr[i]
                if mode == '+' || mode == '-' {
                        plusMinus = mode
                        continue
                }
                if plusMinus != '+' && plusMinus != '-' {
                        return nil, fmt.Errorf("malformed modestring %q: missing plus/minus", modeStr)
                }

                for _, membership := range ch.conn.availableMemberships {
                        if membership.Mode == mode {
                                if nextArgument >= len(arguments) {
                                        return nil, fmt.Errorf("malformed modestring %q: missing mode argument for %c%c", modeStr, plusMinus, mode)
                                }
                                member := arguments[nextArgument]
                                if _, ok := ch.Members[member]; ok {
                                        if plusMinus == '+' {
                                                ch.Members[member].Add(ch.conn.availableMemberships, membership)
                                        } else {
                                                // TODO: for upstreams without multi-prefix, query the user modes again
                                                ch.Members[member].Remove(membership)
                                        }
                                }
                                needMarshaling[nextArgument] = struct{}{}
                                nextArgument++
                                continue outer
                        }
                }

                mt, ok := ch.conn.availableChannelModes[mode]
                if !ok {
                        continue
                }
                if mt == modeTypeB || (mt == modeTypeC && plusMinus == '+') {
                        if plusMinus == '+' {
                                var argument string
                                // some sentitive arguments (such as channel keys) can be omitted for privacy
                                // (this will only happen for RPL_CHANNELMODEIS, never for MODE messages)
                                if nextArgument < len(arguments) {
                                        argument = arguments[nextArgument]
                                }
                                if ch.modes != nil {
                                        ch.modes[mode] = argument
                                }
                        } else {
                                delete(ch.modes, mode)
                        }
                        nextArgument++
                } else if mt == modeTypeC || mt == modeTypeD {
                        if plusMinus == '+' {
                                if ch.modes != nil {
                                        ch.modes[mode] = ""
                                }
                        } else {
                                delete(ch.modes, mode)
                        }
                }
        }
        return needMarshaling, nil
}

func (cm channelModes) Format() (modeString string, parameters []string) {
        var modesWithValues strings.Builder
        var modesWithoutValues strings.Builder
        parameters = make([]string, 0, 16)
        for mode, value := range cm {
                if value != "" {
                        modesWithValues.WriteString(string(mode))
                        parameters = append(parameters, value)
                } else {
                        modesWithoutValues.WriteString(string(mode))
                }
        }
        modeString = "+" + modesWithValues.String() + modesWithoutValues.String()
        return
}

const stdChannelTypes = "#&+!"

type channelStatus byte

const (
        channelPublic  channelStatus = '='
        channelSecret  channelStatus = '@'
        channelPrivate channelStatus = '*'
)

func parseChannelStatus(s string) (channelStatus, error) {
        if len(s) > 1 {
                return 0, fmt.Errorf("invalid channel status %q: more than one character", s)
        }
        switch cs := channelStatus(s[0]); cs {
        case channelPublic, channelSecret, channelPrivate:
                return cs, nil
        default:
                return 0, fmt.Errorf("invalid channel status %q: unknown status", s)
        }
}

type membership struct {
        Mode   byte
        Prefix byte
}

var stdMemberships = []membership{
        {'q', '~'}, // founder
        {'a', '&'}, // protected
        {'o', '@'}, // operator
        {'h', '%'}, // halfop
        {'v', '+'}, // voice
}

// memberships always sorted by descending membership rank
type memberships []membership

func (m *memberships) Add(availableMemberships []membership, newMembership membership) {
        l := *m
        i := 0
        for _, availableMembership := range availableMemberships {
                if i >= len(l) {
                        break
                }
                if l[i] == availableMembership {
                        if availableMembership == newMembership {
                                // we already have this membership
                                return
                        }
                        i++
                        continue
                }
                if availableMembership == newMembership {
                        break
                }
        }
        // insert newMembership at i
        l = append(l, membership{})
        copy(l[i+1:], l[i:])
        l[i] = newMembership
        *m = l
}

func (m *memberships) Remove(oldMembership membership) {
        l := *m
        for i, currentMembership := range l {
                if currentMembership == oldMembership {
                        *m = append(l[:i], l[i+1:]...)
                        return
                }
        }
}

func (m memberships) Format(dc *downstreamConn) string {
        if !dc.caps["multi-prefix"] {
                if len(m) == 0 {
                        return ""
                }
                return string(m[0].Prefix)
        }
        prefixes := make([]byte, len(m))
        for i, membership := range m {
                prefixes[i] = membership.Prefix
        }
        return string(prefixes)
}

func parseMessageParams(msg *irc.Message, out ...*string) error {
        if len(msg.Params) < len(out) {
                return newNeedMoreParamsError(msg.Command)
        }
        for i := range out {
                if out[i] != nil {
                        *out[i] = msg.Params[i]
                }
        }
        return nil
}

func copyClientTags(tags irc.Tags) irc.Tags {
        t := make(irc.Tags, len(tags))
        for k, v := range tags {
                if strings.HasPrefix(k, "+") {
                        t[k] = v
                }
        }
        return t
}

type batch struct {
        Type   string
        Params []string
        Outer  *batch // if not-nil, this batch is nested in Outer
        Label  string
}

func join(channels, keys []string) []*irc.Message {
        // Put channels with a key first
        js := joinSorter{channels, keys}
        sort.Sort(&js)

        // Two spaces because there are three words (JOIN, channels and keys)
        maxLength := maxMessageLength - (len("JOIN") + 2)

        var msgs []*irc.Message
        var channelsBuf, keysBuf strings.Builder
        for i, channel := range channels {
                key := keys[i]

                n := channelsBuf.Len() + keysBuf.Len() + 1 + len(channel)
                if key != "" {
                        n += 1 + len(key)
                }

                if channelsBuf.Len() > 0 && n > maxLength {
                        // No room for the new channel in this message
                        params := []string{channelsBuf.String()}
                        if keysBuf.Len() > 0 {
                                params = append(params, keysBuf.String())
                        }
                        msgs = append(msgs, &irc.Message{Command: "JOIN", Params: params})
                        channelsBuf.Reset()
                        keysBuf.Reset()
                }

                if channelsBuf.Len() > 0 {
                        channelsBuf.WriteByte(',')
                }
                channelsBuf.WriteString(channel)
                if key != "" {
                        if keysBuf.Len() > 0 {
                                keysBuf.WriteByte(',')
                        }
                        keysBuf.WriteString(key)
                }
        }
        if channelsBuf.Len() > 0 {
                params := []string{channelsBuf.String()}
                if keysBuf.Len() > 0 {
                        params = append(params, keysBuf.String())
                }
                msgs = append(msgs, &irc.Message{Command: "JOIN", Params: params})
        }

        return msgs
}

func generateIsupport(prefix *irc.Prefix, nick string, tokens []string) []*irc.Message {
        maxTokens := maxMessageParams - 2 // 2 reserved params: nick + text

        var msgs []*irc.Message
        for len(tokens) > 0 {
                var msgTokens []string
                if len(tokens) > maxTokens {
                        msgTokens = tokens[:maxTokens]
                        tokens = tokens[maxTokens:]
                } else {
                        msgTokens = tokens
                        tokens = nil
                }

                msgs = append(msgs, &irc.Message{
                        Prefix:  prefix,
                        Command: irc.RPL_ISUPPORT,
                        Params:  append(append([]string{nick}, msgTokens...), "are supported"),
                })
        }

        return msgs
}

type joinSorter struct {
        channels []string
        keys     []string
}

func (js *joinSorter) Len() int {
        return len(js.channels)
}

func (js *joinSorter) Less(i, j int) bool {
        if (js.keys[i] != "") != (js.keys[j] != "") {
                // Only one of the channels has a key
                return js.keys[i] != ""
        }
        return js.channels[i] < js.channels[j]
}

func (js *joinSorter) Swap(i, j int) {
        js.channels[i], js.channels[j] = js.channels[j], js.channels[i]
        js.keys[i], js.keys[j] = js.keys[j], js.keys[i]
}

// parseCTCPMessage parses a CTCP message. CTCP is defined in
// https://tools.ietf.org/html/draft-oakley-irc-ctcp-02
func parseCTCPMessage(msg *irc.Message) (cmd string, params string, ok bool) {
        if (msg.Command != "PRIVMSG" && msg.Command != "NOTICE") || len(msg.Params) < 2 {
                return "", "", false
        }
        text := msg.Params[1]

        if !strings.HasPrefix(text, "\x01") {
                return "", "", false
        }
        text = strings.Trim(text, "\x01")

        words := strings.SplitN(text, " ", 2)
        cmd = strings.ToUpper(words[0])
        if len(words) > 1 {
                params = words[1]
        }

        return cmd, params, true
}