471 lines
9.1 KiB
Go
471 lines
9.1 KiB
Go
// Copyright 2012-2017 Apcera Inc. All rights reserved.
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package nats
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import (
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"fmt"
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)
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type msgArg struct {
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subject []byte
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reply []byte
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sid int64
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size int
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}
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const MAX_CONTROL_LINE_SIZE = 1024
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type parseState struct {
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state int
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as int
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drop int
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ma msgArg
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argBuf []byte
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msgBuf []byte
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scratch [MAX_CONTROL_LINE_SIZE]byte
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}
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const (
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OP_START = iota
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OP_PLUS
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OP_PLUS_O
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OP_PLUS_OK
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OP_MINUS
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OP_MINUS_E
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OP_MINUS_ER
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OP_MINUS_ERR
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OP_MINUS_ERR_SPC
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MINUS_ERR_ARG
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OP_M
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OP_MS
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OP_MSG
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OP_MSG_SPC
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MSG_ARG
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MSG_PAYLOAD
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MSG_END
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OP_P
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OP_PI
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OP_PIN
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OP_PING
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OP_PO
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OP_PON
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OP_PONG
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OP_I
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OP_IN
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OP_INF
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OP_INFO
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OP_INFO_SPC
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INFO_ARG
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)
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// parse is the fast protocol parser engine.
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func (nc *Conn) parse(buf []byte) error {
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var i int
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var b byte
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// Move to loop instead of range syntax to allow jumping of i
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for i = 0; i < len(buf); i++ {
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b = buf[i]
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switch nc.ps.state {
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case OP_START:
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switch b {
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case 'M', 'm':
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nc.ps.state = OP_M
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case 'P', 'p':
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nc.ps.state = OP_P
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case '+':
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nc.ps.state = OP_PLUS
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case '-':
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nc.ps.state = OP_MINUS
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case 'I', 'i':
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nc.ps.state = OP_I
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default:
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goto parseErr
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}
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case OP_M:
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switch b {
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case 'S', 's':
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nc.ps.state = OP_MS
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default:
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goto parseErr
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}
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case OP_MS:
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switch b {
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case 'G', 'g':
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nc.ps.state = OP_MSG
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default:
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goto parseErr
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}
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case OP_MSG:
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switch b {
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case ' ', '\t':
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nc.ps.state = OP_MSG_SPC
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default:
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goto parseErr
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}
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case OP_MSG_SPC:
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switch b {
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case ' ', '\t':
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continue
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default:
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nc.ps.state = MSG_ARG
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nc.ps.as = i
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}
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case MSG_ARG:
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switch b {
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case '\r':
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nc.ps.drop = 1
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case '\n':
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var arg []byte
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if nc.ps.argBuf != nil {
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arg = nc.ps.argBuf
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} else {
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arg = buf[nc.ps.as : i-nc.ps.drop]
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}
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if err := nc.processMsgArgs(arg); err != nil {
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return err
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}
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nc.ps.drop, nc.ps.as, nc.ps.state = 0, i+1, MSG_PAYLOAD
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// jump ahead with the index. If this overruns
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// what is left we fall out and process split
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// buffer.
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i = nc.ps.as + nc.ps.ma.size - 1
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default:
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if nc.ps.argBuf != nil {
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nc.ps.argBuf = append(nc.ps.argBuf, b)
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}
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}
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case MSG_PAYLOAD:
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if nc.ps.msgBuf != nil {
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if len(nc.ps.msgBuf) >= nc.ps.ma.size {
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nc.processMsg(nc.ps.msgBuf)
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nc.ps.argBuf, nc.ps.msgBuf, nc.ps.state = nil, nil, MSG_END
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} else {
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// copy as much as we can to the buffer and skip ahead.
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toCopy := nc.ps.ma.size - len(nc.ps.msgBuf)
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avail := len(buf) - i
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if avail < toCopy {
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toCopy = avail
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}
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if toCopy > 0 {
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start := len(nc.ps.msgBuf)
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// This is needed for copy to work.
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nc.ps.msgBuf = nc.ps.msgBuf[:start+toCopy]
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copy(nc.ps.msgBuf[start:], buf[i:i+toCopy])
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// Update our index
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i = (i + toCopy) - 1
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} else {
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nc.ps.msgBuf = append(nc.ps.msgBuf, b)
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}
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}
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} else if i-nc.ps.as >= nc.ps.ma.size {
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nc.processMsg(buf[nc.ps.as:i])
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nc.ps.argBuf, nc.ps.msgBuf, nc.ps.state = nil, nil, MSG_END
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}
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case MSG_END:
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switch b {
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case '\n':
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nc.ps.drop, nc.ps.as, nc.ps.state = 0, i+1, OP_START
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default:
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continue
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}
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case OP_PLUS:
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switch b {
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case 'O', 'o':
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nc.ps.state = OP_PLUS_O
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default:
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goto parseErr
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}
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case OP_PLUS_O:
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switch b {
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case 'K', 'k':
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nc.ps.state = OP_PLUS_OK
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default:
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goto parseErr
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}
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case OP_PLUS_OK:
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switch b {
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case '\n':
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nc.processOK()
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nc.ps.drop, nc.ps.state = 0, OP_START
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}
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case OP_MINUS:
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switch b {
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case 'E', 'e':
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nc.ps.state = OP_MINUS_E
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default:
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goto parseErr
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}
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case OP_MINUS_E:
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switch b {
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case 'R', 'r':
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nc.ps.state = OP_MINUS_ER
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default:
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goto parseErr
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}
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case OP_MINUS_ER:
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switch b {
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case 'R', 'r':
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nc.ps.state = OP_MINUS_ERR
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default:
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goto parseErr
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}
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case OP_MINUS_ERR:
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switch b {
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case ' ', '\t':
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nc.ps.state = OP_MINUS_ERR_SPC
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default:
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goto parseErr
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}
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case OP_MINUS_ERR_SPC:
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switch b {
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case ' ', '\t':
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continue
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default:
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nc.ps.state = MINUS_ERR_ARG
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nc.ps.as = i
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}
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case MINUS_ERR_ARG:
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switch b {
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case '\r':
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nc.ps.drop = 1
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case '\n':
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var arg []byte
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if nc.ps.argBuf != nil {
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arg = nc.ps.argBuf
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nc.ps.argBuf = nil
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} else {
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arg = buf[nc.ps.as : i-nc.ps.drop]
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}
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nc.processErr(string(arg))
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nc.ps.drop, nc.ps.as, nc.ps.state = 0, i+1, OP_START
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default:
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if nc.ps.argBuf != nil {
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nc.ps.argBuf = append(nc.ps.argBuf, b)
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}
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}
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case OP_P:
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switch b {
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case 'I', 'i':
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nc.ps.state = OP_PI
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case 'O', 'o':
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nc.ps.state = OP_PO
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default:
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goto parseErr
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}
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case OP_PO:
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switch b {
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case 'N', 'n':
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nc.ps.state = OP_PON
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default:
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goto parseErr
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}
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case OP_PON:
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switch b {
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case 'G', 'g':
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nc.ps.state = OP_PONG
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default:
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goto parseErr
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}
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case OP_PONG:
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switch b {
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case '\n':
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nc.processPong()
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nc.ps.drop, nc.ps.state = 0, OP_START
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}
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case OP_PI:
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switch b {
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case 'N', 'n':
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nc.ps.state = OP_PIN
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default:
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goto parseErr
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}
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case OP_PIN:
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switch b {
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case 'G', 'g':
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nc.ps.state = OP_PING
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default:
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goto parseErr
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}
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case OP_PING:
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switch b {
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case '\n':
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nc.processPing()
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nc.ps.drop, nc.ps.state = 0, OP_START
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}
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case OP_I:
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switch b {
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case 'N', 'n':
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nc.ps.state = OP_IN
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default:
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goto parseErr
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}
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case OP_IN:
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switch b {
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case 'F', 'f':
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nc.ps.state = OP_INF
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default:
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goto parseErr
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}
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case OP_INF:
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switch b {
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case 'O', 'o':
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nc.ps.state = OP_INFO
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default:
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goto parseErr
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}
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case OP_INFO:
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switch b {
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case ' ', '\t':
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nc.ps.state = OP_INFO_SPC
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default:
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goto parseErr
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}
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case OP_INFO_SPC:
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switch b {
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case ' ', '\t':
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continue
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default:
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nc.ps.state = INFO_ARG
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nc.ps.as = i
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}
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case INFO_ARG:
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switch b {
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case '\r':
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nc.ps.drop = 1
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case '\n':
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var arg []byte
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if nc.ps.argBuf != nil {
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arg = nc.ps.argBuf
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nc.ps.argBuf = nil
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} else {
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arg = buf[nc.ps.as : i-nc.ps.drop]
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}
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nc.processAsyncInfo(arg)
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nc.ps.drop, nc.ps.as, nc.ps.state = 0, i+1, OP_START
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default:
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if nc.ps.argBuf != nil {
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nc.ps.argBuf = append(nc.ps.argBuf, b)
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}
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}
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default:
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goto parseErr
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}
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}
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// Check for split buffer scenarios
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if (nc.ps.state == MSG_ARG || nc.ps.state == MINUS_ERR_ARG || nc.ps.state == INFO_ARG) && nc.ps.argBuf == nil {
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nc.ps.argBuf = nc.ps.scratch[:0]
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nc.ps.argBuf = append(nc.ps.argBuf, buf[nc.ps.as:i-nc.ps.drop]...)
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// FIXME, check max len
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}
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// Check for split msg
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if nc.ps.state == MSG_PAYLOAD && nc.ps.msgBuf == nil {
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// We need to clone the msgArg if it is still referencing the
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// read buffer and we are not able to process the msg.
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if nc.ps.argBuf == nil {
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nc.cloneMsgArg()
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}
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// If we will overflow the scratch buffer, just create a
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// new buffer to hold the split message.
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if nc.ps.ma.size > cap(nc.ps.scratch)-len(nc.ps.argBuf) {
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lrem := len(buf[nc.ps.as:])
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nc.ps.msgBuf = make([]byte, lrem, nc.ps.ma.size)
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copy(nc.ps.msgBuf, buf[nc.ps.as:])
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} else {
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nc.ps.msgBuf = nc.ps.scratch[len(nc.ps.argBuf):len(nc.ps.argBuf)]
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nc.ps.msgBuf = append(nc.ps.msgBuf, (buf[nc.ps.as:])...)
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}
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}
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return nil
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parseErr:
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return fmt.Errorf("nats: Parse Error [%d]: '%s'", nc.ps.state, buf[i:])
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}
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// cloneMsgArg is used when the split buffer scenario has the pubArg in the existing read buffer, but
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// we need to hold onto it into the next read.
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func (nc *Conn) cloneMsgArg() {
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nc.ps.argBuf = nc.ps.scratch[:0]
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nc.ps.argBuf = append(nc.ps.argBuf, nc.ps.ma.subject...)
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nc.ps.argBuf = append(nc.ps.argBuf, nc.ps.ma.reply...)
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nc.ps.ma.subject = nc.ps.argBuf[:len(nc.ps.ma.subject)]
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if nc.ps.ma.reply != nil {
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nc.ps.ma.reply = nc.ps.argBuf[len(nc.ps.ma.subject):]
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}
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}
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const argsLenMax = 4
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func (nc *Conn) processMsgArgs(arg []byte) error {
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// Unroll splitArgs to avoid runtime/heap issues
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a := [argsLenMax][]byte{}
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args := a[:0]
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start := -1
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for i, b := range arg {
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switch b {
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case ' ', '\t', '\r', '\n':
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if start >= 0 {
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args = append(args, arg[start:i])
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start = -1
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}
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default:
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if start < 0 {
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start = i
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}
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}
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}
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if start >= 0 {
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args = append(args, arg[start:])
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}
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switch len(args) {
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case 3:
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nc.ps.ma.subject = args[0]
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nc.ps.ma.sid = parseInt64(args[1])
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nc.ps.ma.reply = nil
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nc.ps.ma.size = int(parseInt64(args[2]))
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case 4:
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nc.ps.ma.subject = args[0]
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nc.ps.ma.sid = parseInt64(args[1])
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nc.ps.ma.reply = args[2]
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nc.ps.ma.size = int(parseInt64(args[3]))
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default:
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return fmt.Errorf("nats: processMsgArgs Parse Error: '%s'", arg)
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}
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if nc.ps.ma.sid < 0 {
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return fmt.Errorf("nats: processMsgArgs Bad or Missing Sid: '%s'", arg)
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}
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if nc.ps.ma.size < 0 {
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return fmt.Errorf("nats: processMsgArgs Bad or Missing Size: '%s'", arg)
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}
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return nil
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}
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// Ascii numbers 0-9
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const (
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ascii_0 = 48
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ascii_9 = 57
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)
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// parseInt64 expects decimal positive numbers. We
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// return -1 to signal error
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func parseInt64(d []byte) (n int64) {
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if len(d) == 0 {
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return -1
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}
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for _, dec := range d {
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if dec < ascii_0 || dec > ascii_9 {
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return -1
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}
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n = n*10 + (int64(dec) - ascii_0)
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}
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return n
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}
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