Golang Message.Size方法代码示例

// Read the version message, calling exit if this is not a supported
// version.
func processVerMsg(msgInit msgInit, exit exitFn) {
	var m core.Message

	msgInit(&m, exit)

	if m.MsgType() != 'V' {
		exit("expected version ('V') message, "+
			"but received %c", m.MsgType())
	}

	// hard-coded lengh limit, but it's very generous
	if m.Size() > 10*KB {
		log.Printf("oversized message string, msg size is %d",
			m.Size())
	}

	s, err := buf.ReadCString(m.Payload())
	if err != nil {
		exit("couldn't read version string: %v", err)
	}

	if !(strings.HasPrefix(s, "PG-9.0") ||
		strings.HasPrefix(s, "PG-9.1") ||
		strings.HasPrefix(s, "PG-9.2") ||
		strings.HasPrefix(s, "PG-9.3") ||
		strings.HasPrefix(s, "PG-9.4") ||
		strings.HasPrefix(s, "PG-9.5")) ||
		!strings.HasSuffix(s, "/logfebe-1") {
		exit("protocol version not supported: %s", s)
	}
}

// Process the identity ('I') message, reporting the identity therein.
func processIdentMsg(msgInit msgInit, exit exitFn) string {
	var m core.Message

	msgInit(&m, exit)

	// Read the remote system identifier string
	if m.MsgType() != 'I' {
		exit("expected identification ('I') message, "+
			"but received %c", m.MsgType())
	}

	// hard-coded lengh limit, but it's very generous
	if m.Size() > 10*KB {
		log.Printf("oversized message string, msg size is %d",
			m.Size())
	}

	s, err := buf.ReadCString(m.Payload())
	if err != nil {
		exit("couldn't read identification string: %v",
			err)
	}

	return s
}

// Process a log message, sending it to the client.
func processLogMsg(die dieCh, primary *logplexc.Client, audit *logplexc.Client,
	msgInit msgInit, sr *serveRecord, exit exitFn) {
	var m core.Message

	for {
		// Poll request to exit
		select {
		case <-die:
			return
		default:
			break
		}

		msgInit(&m, exit)

		// Refuse to handle any log message above an arbitrary
		// size.  Furthermore, exit the worker, closing the0
		// connection, so that the client doesn't even bother
		// to wait for this process to drain the oversized
		// item and anything following it; these will be
		// dropped.  It's on the client to gracefully handle
		// the error and re-connect after this happens.
		if m.Size() > 1*MB {
			exit("client %q sent oversized log record")
		}

		payload, err := m.Force()
		if err != nil {
			exit("could not retrieve payload of message: %v",
				err)
		}

		var lr logRecord
		parseLogRecord(&lr, payload, exit)
		routeLogRecord(&lr, primary, audit, sr, exit)
	}
}

func (c *FrontendConnection) auth(dbcfg VirtualDatabaseConfiguration, sm *fbproto.StartupMessage) bool {
	authFailed := func(sqlstate, format string, v ...interface{}) bool {
		var msg fbcore.Message
		message := fmt.Sprintf(format, v...)
		initFatalMessage(&msg, sqlstate, message)
		_ = c.WriteMessage(&msg)
		_ = c.FlushStream()
		return false
	}

	username, ok := sm.Params["user"]
	if !ok {
		return authFailed("08P01", `required startup parameter "user" nor present in startup packet`)
	}
	dbname, ok := sm.Params["database"]
	if !ok {
		dbname = username
	}
	authMethod, ok := dbcfg.FindDatabase(dbname)
	if !ok {
		return authFailed("3D000", "database %q does not exist", dbname)
	}

	switch authMethod {
	case "trust":
		return true
	case "md5":
		// handled below
	default:
		elog.Errorf("unrecognized authentication method %q", authMethod)
		return authFailed("XX000", "internal error")
	}

	salt := make([]byte, 4)
	_, err := rand.Read(salt)
	if err != nil {
		elog.Errorf("could not generate random salt: %s", err)
		return authFailed("XX000", "internal error")
	}

	var msg fbcore.Message
	buf := &bytes.Buffer{}
	fbbuf.WriteInt32(buf, 5)
	buf.Write(salt)
	msg.InitFromBytes(fbproto.MsgAuthenticationMD5PasswordR, buf.Bytes())
	err = c.WriteAndFlush(&msg)
	if err != nil {
		elog.Logf("error during startup sequence: %s", err)
		return false
	}
	err = c.stream.Next(&msg)
	if err == io.EOF {
		elog.Debugf("EOF during startup sequence")
		return false
	} else if err != nil {
		elog.Logf("error during startup sequence: %s", err)
		return false
	}
	if msg.MsgType() != fbproto.MsgPasswordMessageP {
		return authFailed("08P01", "unexpected response %x", msg.MsgType())
	}
	// don't bother with messages which are clearly too big
	if msg.Size() > 100 {
		return authFailed("28001", "password authentication failed for user %q", username)
	}
	password, err := msg.Force()
	if err != nil {
		elog.Logf("error during startup sequence: %s", err)
		return false
	}
	success, err := dbcfg.MD5Auth(dbname, username, salt, password)
	if err != nil {
		elog.Logf("error during startup sequence: %s", err)
		return false
	}
	if !success {
		return authFailed("28001", "password authentication failed for user %q", username)
	}
	return true
}