25478192467

Committed 06 May 2026 02:32PM UTC coverage: 82.15% (-0.9%) from 83.018%

Build # 25478192467

Build Type

push

github

Committed by

web-flow

Commit Message

Ensure invalid subject characters cannot be forwarded from MQTT to other connection types (#8104)

Some characters are invalid in NATS subjects but were making it in due
to missing MQTT topic validation.

Coverage Stats

76411 of 93014 relevant lines covered (82.15%)

481569.32 hits per line

Source File
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82.86

/server/parser.go

// Copyright 2012-2025 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
        "bufio"
        "bytes"
        "fmt"
        "net/http"
        "net/textproto"
)

type parserState int
type parseState struct {
        state   parserState
        op      byte
        as      int
        drop    int
        pa      pubArg
        argBuf  []byte
        msgBuf  []byte
        header  http.Header // access via getHeader
        scratch [MAX_CONTROL_LINE_SIZE]byte
        argsa   [MAX_HMSG_ARGS + 1][]byte // pre-allocated args array to avoid per-call heap escape
}

type pubArg struct {
        arg       []byte
        pacache   []byte
        origin    []byte
        account   []byte
        subject   []byte
        deliver   []byte
        mapped    []byte
        reply     []byte
        szb       []byte
        hdb       []byte
        queues    [][]byte
        size      int
        hdr       int
        psi       []*serviceImport
        trace     *msgTrace
        delivered bool // Only used for service imports
}

// Parser constants
const (
        OP_START parserState = iota
        OP_PLUS
        OP_PLUS_O
        OP_PLUS_OK
        OP_MINUS
        OP_MINUS_E
        OP_MINUS_ER
        OP_MINUS_ERR
        OP_MINUS_ERR_SPC
        MINUS_ERR_ARG
        OP_C
        OP_CO
        OP_CON
        OP_CONN
        OP_CONNE
        OP_CONNEC
        OP_CONNECT
        CONNECT_ARG
        OP_H
        OP_HP
        OP_HPU
        OP_HPUB
        OP_HPUB_SPC
        HPUB_ARG
        OP_HM
        OP_HMS
        OP_HMSG
        OP_HMSG_SPC
        HMSG_ARG
        OP_P
        OP_PU
        OP_PUB
        OP_PUB_SPC
        PUB_ARG
        OP_PI
        OP_PIN
        OP_PING
        OP_PO
        OP_PON
        OP_PONG
        MSG_PAYLOAD
        MSG_END_R
        MSG_END_N
        OP_S
        OP_SU
        OP_SUB
        OP_SUB_SPC
        SUB_ARG
        OP_A
        OP_ASUB
        OP_ASUB_SPC
        ASUB_ARG
        OP_AUSUB
        OP_AUSUB_SPC
        AUSUB_ARG
        OP_L
        OP_LS
        OP_R
        OP_RS
        OP_U
        OP_UN
        OP_UNS
        OP_UNSU
        OP_UNSUB
        OP_UNSUB_SPC
        UNSUB_ARG
        OP_M
        OP_MS
        OP_MSG
        OP_MSG_SPC
        MSG_ARG
        OP_I
        OP_IN
        OP_INF
        OP_INFO
        INFO_ARG
)

func (c *client) parse(buf []byte) error {
        // Branch out to mqtt clients. c.mqtt is immutable, but should it become
        // an issue (say data race detection), we could branch outside in readLoop
        if c.isMqtt() {
                return c.mqttParse(buf)
        }
        var i int
        var b byte
        var lmsg bool

        // Snapshots
        c.mu.Lock()
        // Snapshot and then reset when we receive a
        // proper CONNECT if needed.
        authSet := c.awaitingAuth()
        // Snapshot max control line as well.
        s, mcl, trace := c.srv, c.mcl, c.trace
        c.mu.Unlock()

        // Move to loop instead of range syntax to allow jumping of i
        for i = 0; i < len(buf); i++ {
                b = buf[i]

                switch c.state {
                case OP_START:
                        c.op = b
                        if b != 'C' && b != 'c' {
                                if authSet {
                                        if s == nil {
                                                goto authErr
                                        }
                                        var ok bool
                                        switch c.kind {
                                        case CLIENT:
                                                // Check here for NoAuthUser. If this is set allow non CONNECT protos as our first.
                                                // E.g. telnet proto demos.
                                                opts := s.getOpts()
                                                noAuthUser := opts.NoAuthUser
                                                if c.ws != nil {
                                                        if noAuthUserWS := opts.Websocket.NoAuthUser; noAuthUserWS != _EMPTY_ {
                                                                noAuthUser = noAuthUserWS
                                                        }
                                                }
                                                if noAuthUser != _EMPTY_ {
                                                        s.mu.Lock()
                                                        user, exists := s.users[noAuthUser]
                                                        s.mu.Unlock()
                                                        if exists {
                                                                c.RegisterUser(user)
                                                                c.mu.Lock()
                                                                c.clearAuthTimer()
                                                                c.flags.set(connectReceived)
                                                                c.mu.Unlock()
                                                                authSet, ok = false, true
                                                        }
                                                }
                                        case LEAF:
                                                // Compressed inbound leaf-node negotiation may require INFO
                                                // before CONNECT. Without compression, leaf connections must
                                                // still start with CONNECT.
                                                ok = (b == 'I' || b == 'i') && needsCompression(s.getOpts().LeafNode.Compression.Mode)
                                        }
                                        if !ok {
                                                goto authErr
                                        }
                                }
                        }
                        switch b {
                        case 'P', 'p':
                                c.state = OP_P
                        case 'H', 'h':
                                c.state = OP_H
                        case 'S', 's':
                                c.state = OP_S
                        case 'U', 'u':
                                c.state = OP_U
                        case 'R', 'r':
                                if c.kind == CLIENT {
                                        goto parseErr
                                } else {
                                        c.state = OP_R
                                }
                        case 'L', 'l':
                                if c.kind != LEAF && c.kind != ROUTER {
                                        goto parseErr
                                } else {
                                        c.state = OP_L
                                }
                        case 'A', 'a':
                                if c.kind == CLIENT {
                                        goto parseErr
                                } else {
                                        c.state = OP_A
                                }
                        case 'C', 'c':
                                c.state = OP_C
                        case 'I', 'i':
                                c.state = OP_I
                        case '+':
                                c.state = OP_PLUS
                        case '-':
                                c.state = OP_MINUS
                        default:
                                goto parseErr
                        }
                case OP_H:
                        switch b {
                        case 'P', 'p':
                                c.state = OP_HP
                        case 'M', 'm':
                                c.state = OP_HM
                        default:
                                goto parseErr
                        }
                case OP_HP:
                        switch b {
                        case 'U', 'u':
                                c.state = OP_HPU
                        default:
                                goto parseErr
                        }
                case OP_HPU:
                        switch b {
                        case 'B', 'b':
                                c.state = OP_HPUB
                        default:
                                goto parseErr
                        }
                case OP_HPUB:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_HPUB_SPC
                        default:
                                goto parseErr
                        }
                case OP_HPUB_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.pa.hdr = 0
                                c.state = HPUB_ARG
                                c.as = i
                        }
                case HPUB_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                if trace {
                                        c.traceInOp("HPUB", arg)
                                }
                                var remaining []byte
                                if i < len(buf) {
                                        remaining = buf[i+1:]
                                }
                                if err := c.processHeaderPub(arg, remaining); err != nil {
                                        return err
                                }

                                c.drop, c.as, c.state = 0, i+1, MSG_PAYLOAD
                                // If we don't have a saved buffer then jump ahead with
                                // the index. If this overruns what is left we fall out
                                // and process split buffer.
                                if c.msgBuf == nil {
                                        i = c.as + c.pa.size - LEN_CR_LF
                                }
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_HM:
                        switch b {
                        case 'S', 's':
                                c.state = OP_HMS
                        default:
                                goto parseErr
                        }
                case OP_HMS:
                        switch b {
                        case 'G', 'g':
                                c.state = OP_HMSG
                        default:
                                goto parseErr
                        }
                case OP_HMSG:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_HMSG_SPC
                        default:
                                goto parseErr
                        }
                case OP_HMSG_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.pa.hdr = 0
                                c.state = HMSG_ARG
                                c.as = i
                        }
                case HMSG_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                var err error
                                if c.kind == ROUTER || c.kind == GATEWAY {
                                        if trace {
                                                c.traceInOp("HMSG", arg)
                                        }
                                        err = c.processRoutedHeaderMsgArgs(arg)
                                } else if c.kind == LEAF {
                                        if trace {
                                                c.traceInOp("HMSG", arg)
                                        }
                                        err = c.processLeafHeaderMsgArgs(arg)
                                }
                                if err != nil {
                                        return err
                                }
                                c.drop, c.as, c.state = 0, i+1, MSG_PAYLOAD

                                // jump ahead with the index. If this overruns
                                // what is left we fall out and process split
                                // buffer.
                                i = c.as + c.pa.size - LEN_CR_LF
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_P:
                        switch b {
                        case 'U', 'u':
                                c.state = OP_PU
                        case 'I', 'i':
                                c.state = OP_PI
                        case 'O', 'o':
                                c.state = OP_PO
                        default:
                                goto parseErr
                        }
                case OP_PU:
                        switch b {
                        case 'B', 'b':
                                c.state = OP_PUB
                        default:
                                goto parseErr
                        }
                case OP_PUB:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_PUB_SPC
                        default:
                                goto parseErr
                        }
                case OP_PUB_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.pa.hdr = -1
                                c.state = PUB_ARG
                                c.as = i
                        }
                case PUB_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                if trace {
                                        c.traceInOp("PUB", arg)
                                }
                                if err := c.processPub(arg); err != nil {
                                        return err
                                }

                                c.drop, c.as, c.state = 0, i+1, MSG_PAYLOAD
                                // If we don't have a saved buffer then jump ahead with
                                // the index. If this overruns what is left we fall out
                                // and process split buffer.
                                if c.msgBuf == nil {
                                        i = c.as + c.pa.size - LEN_CR_LF
                                }
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case MSG_PAYLOAD:
                        if c.msgBuf != nil {
                                // copy as much as we can to the buffer and skip ahead.
                                toCopy := c.pa.size - len(c.msgBuf)
                                avail := len(buf) - i
                                if avail < toCopy {
                                        toCopy = avail
                                }
                                if toCopy > 0 {
                                        start := len(c.msgBuf)
                                        // This is needed for copy to work.
                                        c.msgBuf = c.msgBuf[:start+toCopy]
                                        copy(c.msgBuf[start:], buf[i:i+toCopy])
                                        // Update our index
                                        i = (i + toCopy) - 1
                                } else {
                                        // Fall back to append if needed.
                                        c.msgBuf = append(c.msgBuf, b)
                                }
                                if len(c.msgBuf) >= c.pa.size {
                                        c.state = MSG_END_R
                                }
                        } else if i-c.as+1 >= c.pa.size {
                                c.state = MSG_END_R
                        }
                case MSG_END_R:
                        if b != '\r' {
                                goto parseErr
                        }
                        if c.msgBuf != nil {
                                c.msgBuf = append(c.msgBuf, b)
                        }
                        c.state = MSG_END_N
                case MSG_END_N:
                        if b != '\n' {
                                goto parseErr
                        }
                        if c.msgBuf != nil {
                                c.msgBuf = append(c.msgBuf, b)
                        } else {
                                c.msgBuf = buf[c.as : i+1]
                        }

                        var mt *msgTrace
                        if c.pa.hdr > 0 {
                                mt = c.initMsgTrace()
                        }
                        // Check for mappings.
                        if (c.kind == CLIENT || c.kind == LEAF) && c.in.flags.isSet(hasMappings) {
                                changed := c.selectMappedSubject()
                                if changed {
                                        if trace {
                                                c.traceInOp("MAPPING", []byte(fmt.Sprintf("%s -> %s", c.pa.mapped, c.pa.subject)))
                                        }
                                        // c.pa.subject is the subject the original is now mapped to.
                                        mt.addSubjectMappingEvent(c.pa.subject)
                                }
                        }
                        if trace {
                                c.traceMsg(c.msgBuf)
                        }

                        c.processInboundMsg(c.msgBuf)

                        mt.sendEvent()
                        c.argBuf, c.msgBuf, c.header = nil, nil, nil
                        c.drop, c.as, c.state = 0, i+1, OP_START
                        // Drop all pub args
                        c.pa.arg, c.pa.pacache, c.pa.origin, c.pa.account, c.pa.subject, c.pa.mapped = nil, nil, nil, nil, nil, nil
                        c.pa.reply, c.pa.hdr, c.pa.size, c.pa.szb, c.pa.hdb, c.pa.queues = nil, -1, 0, nil, nil, nil
                        c.pa.trace = nil
                        c.pa.delivered = false
                        lmsg = false
                case OP_A:
                        switch b {
                        case '+':
                                c.state = OP_ASUB
                        case '-', 'u':
                                c.state = OP_AUSUB
                        default:
                                goto parseErr
                        }
                case OP_ASUB:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_ASUB_SPC
                        default:
                                goto parseErr
                        }
                case OP_ASUB_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = ASUB_ARG
                                c.as = i
                        }
                case ASUB_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                if trace {
                                        c.traceInOp("A+", arg)
                                }
                                if err := c.processAccountSub(arg); err != nil {
                                        return err
                                }
                                c.drop, c.as, c.state = 0, i+1, OP_START
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_AUSUB:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_AUSUB_SPC
                        default:
                                goto parseErr
                        }
                case OP_AUSUB_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = AUSUB_ARG
                                c.as = i
                        }
                case AUSUB_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                if trace {
                                        c.traceInOp("A-", arg)
                                }
                                c.processAccountUnsub(arg)
                                c.drop, c.as, c.state = 0, i+1, OP_START
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_S:
                        switch b {
                        case 'U', 'u':
                                c.state = OP_SU
                        default:
                                goto parseErr
                        }
                case OP_SU:
                        switch b {
                        case 'B', 'b':
                                c.state = OP_SUB
                        default:
                                goto parseErr
                        }
                case OP_SUB:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_SUB_SPC
                        default:
                                goto parseErr
                        }
                case OP_SUB_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = SUB_ARG
                                c.as = i
                        }
                case SUB_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                var err error

                                switch c.kind {
                                case CLIENT:
                                        if trace {
                                                c.traceInOp("SUB", arg)
                                        }
                                        err = c.parseSub(arg, false)
                                case ROUTER:
                                        switch c.op {
                                        case 'R', 'r':
                                                if trace {
                                                        c.traceInOp("RS+", arg)
                                                }
                                                err = c.processRemoteSub(arg, false)
                                        case 'L', 'l':
                                                if trace {
                                                        c.traceInOp("LS+", arg)
                                                }
                                                err = c.processRemoteSub(arg, true)
                                        }
                                case GATEWAY:
                                        if trace {
                                                c.traceInOp("RS+", arg)
                                        }
                                        err = c.processGatewayRSub(arg)
                                case LEAF:
                                        if trace {
                                                c.traceInOp("LS+", arg)
                                        }
                                        err = c.processLeafSub(arg)
                                }
                                if err != nil {
                                        return err
                                }
                                c.drop, c.as, c.state = 0, i+1, OP_START
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_L:
                        switch b {
                        case 'S', 's':
                                c.state = OP_LS
                        case 'M', 'm':
                                c.state = OP_M
                        default:
                                goto parseErr
                        }
                case OP_LS:
                        switch b {
                        case '+':
                                c.state = OP_SUB
                        case '-':
                                c.state = OP_UNSUB
                        default:
                                goto parseErr
                        }
                case OP_R:
                        switch b {
                        case 'S', 's':
                                c.state = OP_RS
                        case 'M', 'm':
                                c.state = OP_M
                        default:
                                goto parseErr
                        }
                case OP_RS:
                        switch b {
                        case '+':
                                c.state = OP_SUB
                        case '-':
                                c.state = OP_UNSUB
                        default:
                                goto parseErr
                        }
                case OP_U:
                        switch b {
                        case 'N', 'n':
                                c.state = OP_UN
                        default:
                                goto parseErr
                        }
                case OP_UN:
                        switch b {
                        case 'S', 's':
                                c.state = OP_UNS
                        default:
                                goto parseErr
                        }
                case OP_UNS:
                        switch b {
                        case 'U', 'u':
                                c.state = OP_UNSU
                        default:
                                goto parseErr
                        }
                case OP_UNSU:
                        switch b {
                        case 'B', 'b':
                                c.state = OP_UNSUB
                        default:
                                goto parseErr
                        }
                case OP_UNSUB:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_UNSUB_SPC
                        default:
                                goto parseErr
                        }
                case OP_UNSUB_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = UNSUB_ARG
                                c.as = i
                        }
                case UNSUB_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                var err error

                                switch c.kind {
                                case CLIENT:
                                        if trace {
                                                c.traceInOp("UNSUB", arg)
                                        }
                                        err = c.processUnsub(arg)
                                case ROUTER:
                                        if trace && c.srv != nil {
                                                switch c.op {
                                                case 'R', 'r':
                                                        c.traceInOp("RS-", arg)
                                                case 'L', 'l':
                                                        c.traceInOp("LS-", arg)
                                                }
                                        }
                                        leafUnsub := c.op == 'L' || c.op == 'l'
                                        err = c.processRemoteUnsub(arg, leafUnsub)
                                case GATEWAY:
                                        if trace {
                                                c.traceInOp("RS-", arg)
                                        }
                                        err = c.processGatewayRUnsub(arg)
                                case LEAF:
                                        if trace {
                                                c.traceInOp("LS-", arg)
                                        }
                                        err = c.processLeafUnsub(arg)
                                }
                                if err != nil {
                                        return err
                                }
                                c.drop, c.as, c.state = 0, i+1, OP_START
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_PI:
                        switch b {
                        case 'N', 'n':
                                c.state = OP_PIN
                        default:
                                goto parseErr
                        }
                case OP_PIN:
                        switch b {
                        case 'G', 'g':
                                c.state = OP_PING
                        default:
                                goto parseErr
                        }
                case OP_PING:
                        switch b {
                        case '\n':
                                if trace {
                                        c.traceInOp("PING", nil)
                                }
                                c.processPing()
                                c.drop, c.state = 0, OP_START
                        }
                case OP_PO:
                        switch b {
                        case 'N', 'n':
                                c.state = OP_PON
                        default:
                                goto parseErr
                        }
                case OP_PON:
                        switch b {
                        case 'G', 'g':
                                c.state = OP_PONG
                        default:
                                goto parseErr
                        }
                case OP_PONG:
                        switch b {
                        case '\n':
                                if trace {
                                        c.traceInOp("PONG", nil)
                                }
                                c.processPong()
                                c.drop, c.state = 0, OP_START
                        }
                case OP_C:
                        switch b {
                        case 'O', 'o':
                                c.state = OP_CO
                        default:
                                goto parseErr
                        }
                case OP_CO:
                        switch b {
                        case 'N', 'n':
                                c.state = OP_CON
                        default:
                                goto parseErr
                        }
                case OP_CON:
                        switch b {
                        case 'N', 'n':
                                c.state = OP_CONN
                        default:
                                goto parseErr
                        }
                case OP_CONN:
                        switch b {
                        case 'E', 'e':
                                c.state = OP_CONNE
                        default:
                                goto parseErr
                        }
                case OP_CONNE:
                        switch b {
                        case 'C', 'c':
                                c.state = OP_CONNEC
                        default:
                                goto parseErr
                        }
                case OP_CONNEC:
                        switch b {
                        case 'T', 't':
                                c.state = OP_CONNECT
                        default:
                                goto parseErr
                        }
                case OP_CONNECT:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = CONNECT_ARG
                                c.as = i
                        }
                case CONNECT_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                if trace {
                                        c.traceInOp("CONNECT", removeSecretsFromTrace(arg))
                                }
                                if err := c.processConnect(arg); err != nil {
                                        return err
                                }
                                c.drop, c.state = 0, OP_START
                                // Reset notion on authSet
                                c.mu.Lock()
                                authSet = c.awaitingAuth()
                                c.mu.Unlock()
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_M:
                        switch b {
                        case 'S', 's':
                                c.state = OP_MS
                        default:
                                goto parseErr
                        }
                case OP_MS:
                        switch b {
                        case 'G', 'g':
                                c.state = OP_MSG
                        default:
                                goto parseErr
                        }
                case OP_MSG:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_MSG_SPC
                        default:
                                goto parseErr
                        }
                case OP_MSG_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.pa.hdr = -1
                                c.state = MSG_ARG
                                c.as = i
                        }
                case MSG_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                var err error
                                if c.kind == ROUTER || c.kind == GATEWAY {
                                        switch c.op {
                                        case 'R', 'r':
                                                if trace {
                                                        c.traceInOp("RMSG", arg)
                                                }
                                                err = c.processRoutedMsgArgs(arg)
                                        case 'L', 'l':
                                                if trace {
                                                        c.traceInOp("LMSG", arg)
                                                }
                                                lmsg = true
                                                err = c.processRoutedOriginClusterMsgArgs(arg)
                                        }
                                } else if c.kind == LEAF {
                                        if trace {
                                                c.traceInOp("LMSG", arg)
                                        }
                                        err = c.processLeafMsgArgs(arg)
                                }
                                if err != nil {
                                        return err
                                }
                                c.drop, c.as, c.state = 0, i+1, MSG_PAYLOAD

                                // jump ahead with the index. If this overruns
                                // what is left we fall out and process split
                                // buffer.
                                i = c.as + c.pa.size - LEN_CR_LF
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_I:
                        switch b {
                        case 'N', 'n':
                                c.state = OP_IN
                        default:
                                goto parseErr
                        }
                case OP_IN:
                        switch b {
                        case 'F', 'f':
                                c.state = OP_INF
                        default:
                                goto parseErr
                        }
                case OP_INF:
                        switch b {
                        case 'O', 'o':
                                c.state = OP_INFO
                        default:
                                goto parseErr
                        }
                case OP_INFO:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = INFO_ARG
                                c.as = i
                        }
                case INFO_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                if err := c.processInfo(arg); err != nil {
                                        return err
                                }
                                c.drop, c.as, c.state = 0, i+1, OP_START
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                case OP_PLUS:
                        switch b {
                        case 'O', 'o':
                                c.state = OP_PLUS_O
                        default:
                                goto parseErr
                        }
                case OP_PLUS_O:
                        switch b {
                        case 'K', 'k':
                                c.state = OP_PLUS_OK
                        default:
                                goto parseErr
                        }
                case OP_PLUS_OK:
                        switch b {
                        case '\n':
                                c.drop, c.state = 0, OP_START
                        }
                case OP_MINUS:
                        switch b {
                        case 'E', 'e':
                                c.state = OP_MINUS_E
                        default:
                                goto parseErr
                        }
                case OP_MINUS_E:
                        switch b {
                        case 'R', 'r':
                                c.state = OP_MINUS_ER
                        default:
                                goto parseErr
                        }
                case OP_MINUS_ER:
                        switch b {
                        case 'R', 'r':
                                c.state = OP_MINUS_ERR
                        default:
                                goto parseErr
                        }
                case OP_MINUS_ERR:
                        switch b {
                        case ' ', '\t':
                                c.state = OP_MINUS_ERR_SPC
                        default:
                                goto parseErr
                        }
                case OP_MINUS_ERR_SPC:
                        switch b {
                        case ' ', '\t':
                                continue
                        default:
                                c.state = MINUS_ERR_ARG
                                c.as = i
                        }
                case MINUS_ERR_ARG:
                        switch b {
                        case '\r':
                                c.drop = 1
                        case '\n':
                                var arg []byte
                                if c.argBuf != nil {
                                        arg = c.argBuf
                                        c.argBuf = nil
                                } else {
                                        arg = buf[c.as : i-c.drop]
                                }
                                if err := c.overMaxControlLineLimit(arg, mcl); err != nil {
                                        return err
                                }
                                c.processErr(string(arg))
                                c.drop, c.as, c.state = 0, i+1, OP_START
                        default:
                                if c.argBuf != nil {
                                        c.argBuf = append(c.argBuf, b)
                                }
                        }
                default:
                        goto parseErr
                }
        }

        // Check for split buffer scenarios for any ARG state.
        if c.state == SUB_ARG || c.state == UNSUB_ARG ||
                c.state == PUB_ARG || c.state == HPUB_ARG ||
                c.state == ASUB_ARG || c.state == AUSUB_ARG ||
                c.state == MSG_ARG || c.state == HMSG_ARG ||
                c.state == MINUS_ERR_ARG || c.state == CONNECT_ARG || c.state == INFO_ARG {

                // Setup a holder buffer to deal with split buffer scenario.
                if c.argBuf == nil {
                        c.argBuf = c.scratch[:0]
                        c.argBuf = append(c.argBuf, buf[c.as:i-c.drop]...)
                }
                // Check for violations of control line length here. Note that this is not
                // exact at all but the performance hit is too great to be precise, and
                // catching here should prevent memory exhaustion attacks.
                if err := c.overMaxControlLineLimit(c.argBuf, mcl); err != nil {
                        return err
                }
        }

        // Check for split msg
        if (c.state == MSG_PAYLOAD || c.state == MSG_END_R || c.state == MSG_END_N) && c.msgBuf == nil {
                // We need to clone the pubArg if it is still referencing the
                // read buffer and we are not able to process the msg.

                if c.argBuf == nil {
                        // Works also for MSG_ARG, when message comes from ROUTE or GATEWAY.
                        if err := c.clonePubArg(lmsg); err != nil {
                                goto parseErr
                        }
                }

                // If we will overflow the scratch buffer, just create a
                // new buffer to hold the split message.
                if c.pa.size > cap(c.scratch)-len(c.argBuf) {
                        lrem := len(buf[c.as:])
                        // Consider it a protocol error when the remaining payload
                        // is larger than the reported size for PUB. It can happen
                        // when processing incomplete messages from rogue clients.
                        if lrem > c.pa.size+LEN_CR_LF {
                                goto parseErr
                        }
                        c.msgBuf = make([]byte, lrem, c.pa.size+LEN_CR_LF)
                        copy(c.msgBuf, buf[c.as:])
                } else {
                        c.msgBuf = c.scratch[len(c.argBuf):len(c.argBuf)]
                        c.msgBuf = append(c.msgBuf, (buf[c.as:])...)
                }
        }

        return nil

authErr:
        c.authViolation()
        return ErrAuthentication

parseErr:
        c.sendErr("Unknown Protocol Operation")
        snip := protoSnippet(i, PROTO_SNIPPET_SIZE, buf)
        err := fmt.Errorf("%s parser ERROR, state=%d, i=%d: proto='%s...'", c.kindString(), c.state, i, snip)
        return err
}

func protoSnippet(start, max int, buf []byte) string {
        stop := start + max
        bufSize := len(buf)
        if start >= bufSize {
                return `""`
        }
        if stop > bufSize {
                stop = bufSize - 1
        }
        return fmt.Sprintf("%q", buf[start:stop])
}

// Check if the length of buffer `arg` is over the max control line limit `mcl`.
// If so, an error is sent to the client and the connection is closed.
// The error ErrMaxControlLine is returned.
func (c *client) overMaxControlLineLimit(arg []byte, mcl int32) error {
        // Widen to int64 so mcl*16 cannot overflow for large configured values.
        effective := int64(mcl)
        if c.kind != CLIENT {
                // This is the upper bound on argBuf length for LEAF, ROUTER, and GATEWAY connections.
                // These kinds need longer arg lines than CLIENT (which is capped at mcl=4096 by default)
                // because cluster/leaf frames encode origin, account, reply, and queue groups.
                // By default, this is 64 KB, which matches maxBufSize so a single oversized read
                // is caught on the very next parse call.
                effective *= 16
        }
        if int64(len(arg)) > effective {
                err := NewErrorCtx(ErrMaxControlLine, "State %d, max_control_line %d, Buffer len %d (snip: %s...)",
                        c.state, int(mcl), len(c.argBuf), protoSnippet(0, MAX_CONTROL_LINE_SNIPPET_SIZE, arg))
                c.sendErr(err.Error())
                c.closeConnection(MaxControlLineExceeded)
                return err
        }
        return nil
}

// clonePubArg is used when the split buffer scenario has the pubArg in the existing read buffer, but
// we need to hold onto it into the next read.
func (c *client) clonePubArg(lmsg bool) error {
        // Just copy and re-process original arg buffer.
        c.argBuf = c.scratch[:0]
        c.argBuf = append(c.argBuf, c.pa.arg...)

        switch c.kind {
        case ROUTER, GATEWAY:
                if lmsg {
                        return c.processRoutedOriginClusterMsgArgs(c.argBuf)
                }
                if c.pa.hdr < 0 {
                        return c.processRoutedMsgArgs(c.argBuf)
                } else {
                        return c.processRoutedHeaderMsgArgs(c.argBuf)
                }
        case LEAF:
                if c.pa.hdr < 0 {
                        return c.processLeafMsgArgs(c.argBuf)
                } else {
                        return c.processLeafHeaderMsgArgs(c.argBuf)
                }
        default:
                if c.pa.hdr < 0 {
                        return c.processPub(c.argBuf)
                } else {
                        return c.processHeaderPub(c.argBuf, nil)
                }
        }
}

func (ps *parseState) getHeader() http.Header {
        if ps.header == nil {
                if hdr := ps.pa.hdr; hdr > 0 {
                        reader := bufio.NewReader(bytes.NewReader(ps.msgBuf[0:hdr]))
                        tp := textproto.NewReader(reader)
                        tp.ReadLine() // skip over first line, contains version
                        if mimeHeader, err := tp.ReadMIMEHeader(); err == nil {
                                ps.header = http.Header(mimeHeader)
                        }
                }
        }
        return ps.header
}

nats-io / nats-server / 25478192467

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