Cameron Sparr
274
plugins/inputs/phpfpm/fcgi.go
Normal file
274
plugins/inputs/phpfpm/fcgi.go
Normal file
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package fcgi implements the FastCGI protocol.
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// Currently only the responder role is supported.
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// The protocol is defined at http://www.fastcgi.com/drupal/node/6?q=node/22
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package phpfpm
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// This file defines the raw protocol and some utilities used by the child and
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// the host.
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import (
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"bufio"
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"bytes"
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"encoding/binary"
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"errors"
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"io"
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"sync"
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)
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// recType is a record type, as defined by
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// http://www.fastcgi.com/devkit/doc/fcgi-spec.html#S8
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type recType uint8
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const (
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typeBeginRequest recType = 1
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typeAbortRequest recType = 2
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typeEndRequest recType = 3
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typeParams recType = 4
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typeStdin recType = 5
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typeStdout recType = 6
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typeStderr recType = 7
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typeData recType = 8
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typeGetValues recType = 9
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typeGetValuesResult recType = 10
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typeUnknownType recType = 11
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)
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// keep the connection between web-server and responder open after request
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const flagKeepConn = 1
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const (
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maxWrite = 65535 // maximum record body
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maxPad = 255
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)
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const (
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roleResponder = iota + 1 // only Responders are implemented.
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roleAuthorizer
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roleFilter
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)
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const (
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statusRequestComplete = iota
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statusCantMultiplex
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statusOverloaded
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statusUnknownRole
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)
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const headerLen = 8
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type header struct {
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Version uint8
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Type recType
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Id uint16
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ContentLength uint16
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PaddingLength uint8
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Reserved uint8
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}
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type beginRequest struct {
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role uint16
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flags uint8
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reserved [5]uint8
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}
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func (br *beginRequest) read(content []byte) error {
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if len(content) != 8 {
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return errors.New("fcgi: invalid begin request record")
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}
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br.role = binary.BigEndian.Uint16(content)
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br.flags = content[2]
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return nil
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}
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// for padding so we don't have to allocate all the time
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// not synchronized because we don't care what the contents are
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var pad [maxPad]byte
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func (h *header) init(recType recType, reqId uint16, contentLength int) {
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h.Version = 1
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h.Type = recType
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h.Id = reqId
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h.ContentLength = uint16(contentLength)
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h.PaddingLength = uint8(-contentLength & 7)
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}
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// conn sends records over rwc
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type conn struct {
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mutex sync.Mutex
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rwc io.ReadWriteCloser
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// to avoid allocations
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buf bytes.Buffer
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h header
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}
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func newConn(rwc io.ReadWriteCloser) *conn {
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return &conn{rwc: rwc}
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}
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func (c *conn) Close() error {
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c.mutex.Lock()
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defer c.mutex.Unlock()
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return c.rwc.Close()
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}
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type record struct {
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h header
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buf [maxWrite + maxPad]byte
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}
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func (rec *record) read(r io.Reader) (err error) {
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if err = binary.Read(r, binary.BigEndian, &rec.h); err != nil {
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return err
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}
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if rec.h.Version != 1 {
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return errors.New("fcgi: invalid header version")
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}
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n := int(rec.h.ContentLength) + int(rec.h.PaddingLength)
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if _, err = io.ReadFull(r, rec.buf[:n]); err != nil {
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return err
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}
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return nil
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}
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func (r *record) content() []byte {
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return r.buf[:r.h.ContentLength]
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}
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// writeRecord writes and sends a single record.
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func (c *conn) writeRecord(recType recType, reqId uint16, b []byte) error {
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c.mutex.Lock()
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defer c.mutex.Unlock()
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c.buf.Reset()
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c.h.init(recType, reqId, len(b))
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if err := binary.Write(&c.buf, binary.BigEndian, c.h); err != nil {
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return err
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}
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if _, err := c.buf.Write(b); err != nil {
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return err
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}
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if _, err := c.buf.Write(pad[:c.h.PaddingLength]); err != nil {
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return err
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}
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_, err := c.rwc.Write(c.buf.Bytes())
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return err
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}
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func (c *conn) writeBeginRequest(reqId uint16, role uint16, flags uint8) error {
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b := [8]byte{byte(role >> 8), byte(role), flags}
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return c.writeRecord(typeBeginRequest, reqId, b[:])
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}
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func (c *conn) writeEndRequest(reqId uint16, appStatus int, protocolStatus uint8) error {
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b := make([]byte, 8)
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binary.BigEndian.PutUint32(b, uint32(appStatus))
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b[4] = protocolStatus
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return c.writeRecord(typeEndRequest, reqId, b)
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}
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func (c *conn) writePairs(recType recType, reqId uint16, pairs map[string]string) error {
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w := newWriter(c, recType, reqId)
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b := make([]byte, 8)
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for k, v := range pairs {
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n := encodeSize(b, uint32(len(k)))
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n += encodeSize(b[n:], uint32(len(v)))
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if _, err := w.Write(b[:n]); err != nil {
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return err
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}
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if _, err := w.WriteString(k); err != nil {
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return err
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}
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if _, err := w.WriteString(v); err != nil {
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return err
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}
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}
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w.Close()
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return nil
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}
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func readSize(s []byte) (uint32, int) {
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if len(s) == 0 {
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return 0, 0
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}
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size, n := uint32(s[0]), 1
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if size&(1<<7) != 0 {
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if len(s) < 4 {
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return 0, 0
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}
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n = 4
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size = binary.BigEndian.Uint32(s)
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size &^= 1 << 31
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}
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return size, n
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}
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func readString(s []byte, size uint32) string {
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if size > uint32(len(s)) {
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return ""
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}
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return string(s[:size])
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}
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func encodeSize(b []byte, size uint32) int {
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if size > 127 {
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size |= 1 << 31
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binary.BigEndian.PutUint32(b, size)
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return 4
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}
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b[0] = byte(size)
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return 1
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}
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// bufWriter encapsulates bufio.Writer but also closes the underlying stream when
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// Closed.
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type bufWriter struct {
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closer io.Closer
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*bufio.Writer
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}
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func (w *bufWriter) Close() error {
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if err := w.Writer.Flush(); err != nil {
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w.closer.Close()
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return err
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}
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return w.closer.Close()
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}
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func newWriter(c *conn, recType recType, reqId uint16) *bufWriter {
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s := &streamWriter{c: c, recType: recType, reqId: reqId}
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w := bufio.NewWriterSize(s, maxWrite)
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return &bufWriter{s, w}
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}
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// streamWriter abstracts out the separation of a stream into discrete records.
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// It only writes maxWrite bytes at a time.
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type streamWriter struct {
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c *conn
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recType recType
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reqId uint16
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}
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func (w *streamWriter) Write(p []byte) (int, error) {
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nn := 0
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for len(p) > 0 {
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n := len(p)
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if n > maxWrite {
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n = maxWrite
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}
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if err := w.c.writeRecord(w.recType, w.reqId, p[:n]); err != nil {
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return nn, err
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}
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nn += n
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p = p[n:]
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}
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return nn, nil
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}
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func (w *streamWriter) Close() error {
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// send empty record to close the stream
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return w.c.writeRecord(w.recType, w.reqId, nil)
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}
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