telegraf/plugins/inputs/phpfpm/fcgi.go

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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package fcgi implements the FastCGI protocol.
// Currently only the responder role is supported.
// The protocol is defined at http://www.fastcgi.com/drupal/node/6?q=node/22
package phpfpm
// This file defines the raw protocol and some utilities used by the child and
// the host.
import (
"bufio"
"bytes"
"encoding/binary"
"errors"
"io"
"sync"
)
// recType is a record type, as defined by
// http://www.fastcgi.com/devkit/doc/fcgi-spec.html#S8
type recType uint8
const (
typeBeginRequest recType = 1
typeAbortRequest recType = 2
typeEndRequest recType = 3
typeParams recType = 4
typeStdin recType = 5
typeStdout recType = 6
typeStderr recType = 7
typeData recType = 8
typeGetValues recType = 9
typeGetValuesResult recType = 10
typeUnknownType recType = 11
)
// keep the connection between web-server and responder open after request
const flagKeepConn = 1
const (
maxWrite = 65535 // maximum record body
maxPad = 255
)
const (
roleResponder = iota + 1 // only Responders are implemented.
roleAuthorizer
roleFilter
)
const (
statusRequestComplete = iota
statusCantMultiplex
statusOverloaded
statusUnknownRole
)
const headerLen = 8
type header struct {
Version uint8
Type recType
Id uint16
ContentLength uint16
PaddingLength uint8
Reserved uint8
}
type beginRequest struct {
role uint16
flags uint8
reserved [5]uint8
}
func (br *beginRequest) read(content []byte) error {
if len(content) != 8 {
return errors.New("fcgi: invalid begin request record")
}
br.role = binary.BigEndian.Uint16(content)
br.flags = content[2]
return nil
}
// for padding so we don't have to allocate all the time
// not synchronized because we don't care what the contents are
var pad [maxPad]byte
func (h *header) init(recType recType, reqId uint16, contentLength int) {
h.Version = 1
h.Type = recType
h.Id = reqId
h.ContentLength = uint16(contentLength)
h.PaddingLength = uint8(-contentLength & 7)
}
// conn sends records over rwc
type conn struct {
mutex sync.Mutex
rwc io.ReadWriteCloser
// to avoid allocations
buf bytes.Buffer
h header
}
func newConn(rwc io.ReadWriteCloser) *conn {
return &conn{rwc: rwc}
}
func (c *conn) Close() error {
c.mutex.Lock()
defer c.mutex.Unlock()
return c.rwc.Close()
}
type record struct {
h header
buf [maxWrite + maxPad]byte
}
func (rec *record) read(r io.Reader) (err error) {
if err = binary.Read(r, binary.BigEndian, &rec.h); err != nil {
return err
}
if rec.h.Version != 1 {
return errors.New("fcgi: invalid header version")
}
n := int(rec.h.ContentLength) + int(rec.h.PaddingLength)
if _, err = io.ReadFull(r, rec.buf[:n]); err != nil {
return err
}
return nil
}
func (r *record) content() []byte {
return r.buf[:r.h.ContentLength]
}
// writeRecord writes and sends a single record.
func (c *conn) writeRecord(recType recType, reqId uint16, b []byte) error {
c.mutex.Lock()
defer c.mutex.Unlock()
c.buf.Reset()
c.h.init(recType, reqId, len(b))
if err := binary.Write(&c.buf, binary.BigEndian, c.h); err != nil {
return err
}
if _, err := c.buf.Write(b); err != nil {
return err
}
if _, err := c.buf.Write(pad[:c.h.PaddingLength]); err != nil {
return err
}
_, err := c.rwc.Write(c.buf.Bytes())
return err
}
func (c *conn) writeBeginRequest(reqId uint16, role uint16, flags uint8) error {
b := [8]byte{byte(role >> 8), byte(role), flags}
return c.writeRecord(typeBeginRequest, reqId, b[:])
}
func (c *conn) writeEndRequest(reqId uint16, appStatus int, protocolStatus uint8) error {
b := make([]byte, 8)
binary.BigEndian.PutUint32(b, uint32(appStatus))
b[4] = protocolStatus
return c.writeRecord(typeEndRequest, reqId, b)
}
func (c *conn) writePairs(recType recType, reqId uint16, pairs map[string]string) error {
w := newWriter(c, recType, reqId)
b := make([]byte, 8)
for k, v := range pairs {
n := encodeSize(b, uint32(len(k)))
n += encodeSize(b[n:], uint32(len(v)))
if _, err := w.Write(b[:n]); err != nil {
return err
}
if _, err := w.WriteString(k); err != nil {
return err
}
if _, err := w.WriteString(v); err != nil {
return err
}
}
w.Close()
return nil
}
func readSize(s []byte) (uint32, int) {
if len(s) == 0 {
return 0, 0
}
size, n := uint32(s[0]), 1
if size&(1<<7) != 0 {
if len(s) < 4 {
return 0, 0
}
n = 4
size = binary.BigEndian.Uint32(s)
size &^= 1 << 31
}
return size, n
}
func readString(s []byte, size uint32) string {
if size > uint32(len(s)) {
return ""
}
return string(s[:size])
}
func encodeSize(b []byte, size uint32) int {
if size > 127 {
size |= 1 << 31
binary.BigEndian.PutUint32(b, size)
return 4
}
b[0] = byte(size)
return 1
}
// bufWriter encapsulates bufio.Writer but also closes the underlying stream when
// Closed.
type bufWriter struct {
closer io.Closer
*bufio.Writer
}
func (w *bufWriter) Close() error {
if err := w.Writer.Flush(); err != nil {
w.closer.Close()
return err
}
return w.closer.Close()
}
func newWriter(c *conn, recType recType, reqId uint16) *bufWriter {
s := &streamWriter{c: c, recType: recType, reqId: reqId}
w := bufio.NewWriterSize(s, maxWrite)
return &bufWriter{s, w}
}
// streamWriter abstracts out the separation of a stream into discrete records.
// It only writes maxWrite bytes at a time.
type streamWriter struct {
c *conn
recType recType
reqId uint16
}
func (w *streamWriter) Write(p []byte) (int, error) {
nn := 0
for len(p) > 0 {
n := len(p)
if n > maxWrite {
n = maxWrite
}
if err := w.c.writeRecord(w.recType, w.reqId, p[:n]); err != nil {
return nn, err
}
nn += n
p = p[n:]
}
return nn, nil
}
func (w *streamWriter) Close() error {
// send empty record to close the stream
return w.c.writeRecord(w.recType, w.reqId, nil)
}