Golang Buffer.Write方法代码示例

func faiConnection(conn *net.TCPConn) {
	defer conn.Close()
	var err error

	err = conn.SetKeepAlive(true)
	if err != nil {
		util.Log(0, "ERROR! SetKeepAlive: %v", err)
	}

	var buf bytes.Buffer
	defer buf.Reset()
	readbuf := make([]byte, 4096)
	n := 1
	for n != 0 {
		n, err = conn.Read(readbuf)
		if err != nil && err != io.EOF {
			util.Log(0, "ERROR! Read: %v", err)
		}
		if n == 0 && err == nil {
			util.Log(0, "ERROR! Read 0 bytes but no error reported")
		}

		// Find complete lines terminated by '\n' and process them.
		for start := 0; ; {
			eol := start
			for ; eol < n; eol++ {
				if readbuf[eol] == '\n' {
					break
				}
			}

			// no \n found, append to buf and continue reading
			if eol == n {
				buf.Write(readbuf[start:n])
				break
			}

			// append to rest of line to buffered contents
			buf.Write(readbuf[start:eol])
			start = eol + 1

			buf.TrimSpace()

			util.Log(2, "DEBUG! FAI monitor message from %v: %v", conn.RemoteAddr(), buf.String())
			buf.Reset()
		}
	}

	if buf.Len() != 0 {
		util.Log(2, "DEBUG! Incomplete FAI monitor message (i.e. not terminated by \"\\n\") from %v: %v", conn.RemoteAddr(), buf.String())
	}
}

func main() {
	if len(os.Args) != 3 && len(os.Args) != 2 {
		fmt.Fprintf(os.Stderr, "USAGE: %v", USAGE)
		os.Exit(0)
	}

	var input bytes.Buffer
	defer input.Reset()
	if len(os.Args) == 3 {
		input.WriteString(os.Args[2])
	} else {
		buf, err := ioutil.ReadAll(os.Stdin)
		if err != nil {
			fmt.Fprintf(os.Stderr, "%v", err)
			os.Exit(1)
		}
		input.Write(buf)
	}
	security.GosaEncryptBuffer(&input, os.Args[1])
	fmt.Fprintln(os.Stdout, input.String())
}

// Handles the message "gosa_get_log_file_by_date_and_mac".
//  xmlmsg: the decrypted and parsed message
// Returns:
//  unencrypted reply
func gosa_get_log_file_by_date_and_mac(xmlmsg *xml.Hash) *xml.Hash {
	macaddress := xmlmsg.Text("mac")
	lmac := strings.ToLower(macaddress)
	subdir := xmlmsg.Text("date")
	log_file := xmlmsg.Text("log_file")

	header := "get_log_file_by_date_and_mac"
	x := xml.NewHash("xml", "header", header)
	x.Add(header)
	x.Add("source", config.ServerSourceAddress)
	x.Add("target", "GOSA")
	x.Add("session_id", "1")

	if !macAddressRegexp.MatchString(macaddress) {
		emsg := fmt.Sprintf("Illegal or missing <mac> element in message: %v", xmlmsg)
		util.Log(0, "ERROR! %v", emsg)
		return ErrorReplyXML(emsg)
	}

	// As a precaution, make sure subdir and log_file contain no slashes.
	subdir = strings.Replace(subdir, "/", "_", -1)
	log_file = strings.Replace(log_file, "/", "_", -1)

	if subdir == "" {
		// When you open the installation logs in GOsa for the first time, GOsa sends
		// a broken request that is characterized by an empty <date> and log_file==0.
		// If we return an error, GOsa presents it to the user which
		// gives a bad experience. So we instead return an empty reply in this special case.
		if log_file == "0" {
			return x
		}
		emsg := fmt.Sprintf("Missing or empty <date> element in message: %v", xmlmsg)
		util.Log(0, "ERROR! %v", emsg)
		return ErrorReplyXML(emsg)
	}

	if log_file == "" {
		emsg := fmt.Sprintf("Missing or empty <log_file> element in message: %v", xmlmsg)
		util.Log(0, "ERROR! %v", emsg)
		return ErrorReplyXML(emsg)
	}

	f, err := os.Open(path.Join(config.FAILogPath, lmac, subdir, log_file))
	if err != nil {
		emsg := fmt.Sprintf("gosa_get_log_file_by_date_and_mac: %v", err)
		util.Log(0, "ERROR! %v", emsg)
		return ErrorReplyXML(emsg)
	}
	defer f.Close()

	var b bytes.Buffer
	defer b.Reset()
	buffy := make([]byte, 65536)
	for {
		n, err := f.Read(buffy)
		b.Write(buffy[0:n])
		if err == io.EOF {
			break
		}
		if err != nil {
			emsg := fmt.Sprintf("gosa_get_log_file_by_date_and_mac: %v", err)
			util.Log(0, "ERROR! %v", emsg)
			return ErrorReplyXML(emsg)
		}
		if n == 0 {
			util.Log(0, "WARNING! Read returned 0 bytes but no error. Assuming EOF")
			break
		}
	}

	idx := (((b.Len() + 2) / 3) << 2) - b.Len()
	b.Write0(idx)
	data := b.Bytes()
	copy(data[idx:], data)
	data = util.Base64EncodeInPlace(data, idx)

	data_element := x.Add(log_file)

	// To reduce memory leak potential, we append in pieces rather than as one large string
	end := xml.MaxFragmentLength
	for ; end < len(data); end += xml.MaxFragmentLength {
		data_element.AppendString(string(data[end-xml.MaxFragmentLength : end]))
	}
	data_element.AppendString(string(data[end-xml.MaxFragmentLength:]))

	return x
}

func testBuffer() {
	var b bytes.Buffer
	check(b.String(), "") // String() on fresh variable
	b.Reset()             // Reset() on fresh variable
	check(b.String(), "") // String() after Reset()
	b.Reset()             // Reset() after Reset()
	check(b.String(), "")
	check(b.Len(), 0)

	// same tests as above with pointer
	b2 := &bytes.Buffer{}
	check(b2.String(), "")
	b2.Reset()
	check(b2.String(), "")
	b2.Reset()
	check(b2.String(), "")
	check(b2.Len(), 0)

	b2.WriteString("Dies ist ein Test!")
	check(b2.String(), "Dies ist ein Test!")
	check(b2.Len(), 18)

	n, err := b.Write(nil)
	check(n, 0)
	check(err, nil)
	check(b.String(), "")

	n, err = b.Write([]byte{})
	check(n, 0)
	check(err, nil)
	check(b.String(), "")
	check(b.Pointer(), nil)
	check(b.Capacity(), 0)
	check(b.Len(), 0)

	func() {
		defer func() {
			check(recover(), bytes.ErrTooLarge)
		}()
		b.Grow(-1)
	}()

	n, err = b.Write([]byte{'a'})
	check(n, 1)
	check(err, nil)
	check(b.String(), "a")
	check(b.Capacity() >= 1, true)
	check(b.Len(), 1)
	check(b.Pointer() != nil, true)

	check(b.Grow(11), 1)
	check(b.Capacity() >= 12, true)
	c := b.Capacity()
	p := b.Pointer()
	check(b.Grow(11), 1) // should not cause actual growth
	check(b.Pointer(), p)
	check(b.Capacity(), c)
	check(b.Len(), 1)
	((*[2]byte)(b.Pointer()))[1] = 'z'
	check(b.Contains("z"), false)

	n, err = b.WriteString("Hallo")
	check(n, 5)
	check(err, nil)
	check(b.String(), "aHallo")
	check(b.Pointer(), p)
	check(b.Capacity(), c)
	check(b.Len(), 6)

	b.Reset()
	check(b.String(), "")
	check(b.Pointer(), nil)
	check(b.Capacity(), 0)
	check(b.Contains(""), true)
	check(b.Contains("a"), false)

	b.WriteString("Hallo")
	b.WriteByte(' ')
	b.Write([]byte{'d', 'i', 'e', 's'})
	b.WriteByte(' ')
	b.WriteString("ist ")
	b.WriteString("ein ")
	b.Write([]byte("Test"))
	check(b.String(), "Hallo dies ist ein Test")
	check(b.Contains("Hallo dies ist ein Test"), true)
	check(b.Contains("Test"), true)
	check(b.Contains("Hallo"), true)
	check(b.Contains("allo"), true)
	check(b.Contains(""), true)

	check(b.Split(" "), []string{"Hallo", "dies", "ist", "ein", "Test"})
	check(b.Split("X"), []string{"Hallo dies ist ein Test"})
	check(b.Split("Hallo dies ist ein Test"), []string{"", ""})
	check(b.Split("H"), []string{"", "allo dies ist ein Test"})
	check(b.Split("Test"), []string{"Hallo dies ist ein ", ""})
	check(b.Split("es"), []string{"Hallo di", " ist ein T", "t"})

	b.Reset()
	b.WriteString("  \n\t Hallo  \t\v\n")
	check(b.Len(), 15)
//.........这里部分代码省略.........

// Handles one or more messages received over conn. Each message is a single
// line terminated by \n. The message may be encrypted as by security.GosaEncrypt().
func handle_request(tcpconn *net.TCPConn) {
	defer tcpconn.Close()
	defer atomic.AddInt32(&ActiveConnections, -1)

	//  defer util.Log(2, "DEBUG! Connection to %v closed", tcpconn.RemoteAddr())
	//  util.Log(2, "DEBUG! Connection from %v", tcpconn.RemoteAddr())

	var err error

	err = tcpconn.SetKeepAlive(true)
	if err != nil {
		util.Log(0, "ERROR! SetKeepAlive: %v", err)
	}

	var buf bytes.Buffer
	defer buf.Reset()
	readbuf := make([]byte, 4096)

	var conn net.Conn
	conn = tcpconn
	n := 1

	if config.TLSServerConfig != nil {
		// If TLS is required, we need to see a STARTTLS before the timeout.
		// If TLS is optional we need to accept idle connections for backwards compatibility
		if config.TLSRequired {
			conn.SetDeadline(time.Now().Add(config.TimeoutTLS))
		}

		for i := range starttls {
			n, err = conn.Read(readbuf[0:1])
			if n == 0 {
				if i != 0 { // Do not log an error for a port scan that just opens a connection and closes it immediately
					util.Log(0, "ERROR! Read error while looking for STARTTLS from %v: %v", conn.RemoteAddr(), err)
				}
				return
			}
			buf.Write(readbuf[0:1])
			if readbuf[0] == '\r' && starttls[i] == '\n' {
				// Read the \n that must follow \r (we don't support lone CR line endings)
				conn.Read(readbuf[0:1]) // ignore error. It will pop up again further down the line.
			}
			if readbuf[0] != starttls[i] {
				if config.TLSRequired {
					util.Log(0, "ERROR! No STARTTLS from %v, but TLS is required", conn.RemoteAddr())
					util.WriteAll(conn, []byte(message.ErrorReply("STARTTLS is required to connect")))
					return
				}
				break
			}
			if readbuf[0] == '\n' {
				buf.Reset() // purge STARTTLS\n from buffer
				conn = tls.Server(conn, config.TLSServerConfig)
			}
		}
	}

	context := security.ContextFor(conn)
	if context == nil {
		return
	}

	for n != 0 {
		//util.Log(2, "DEBUG! Receiving from %v", conn.RemoteAddr())
		n, err = conn.Read(readbuf)

		if err != nil && err != io.EOF {
			util.Log(0, "ERROR! Read: %v", err)
		}
		if err == io.EOF {
			util.Log(2, "DEBUG! Connection closed by %v", conn.RemoteAddr())
		}
		if n == 0 && err == nil {
			util.Log(0, "ERROR! Read 0 bytes but no error reported")
		}

		// Find complete lines terminated by '\n' and process them.
		for start := 0; ; {
			eol := start
			for ; eol < n; eol++ {
				if readbuf[eol] == '\n' {
					break
				}
			}

			// no \n found, append to buf and continue reading
			if eol == n {
				buf.Write(readbuf[start:n])
				break
			}

			// append to rest of line to buffered contents
			buf.Write(readbuf[start:eol])
			start = eol + 1

			buf.TrimSpace()

			// process the message and get a reply (if applicable)
//.........这里部分代码省略.........