http/fcgi: New package

R=golang-dev, bradfitzgo, bradfitzwork, nigeltao, rog
CC=golang-dev
https://golang.org/cl/4271078

5 files changed, 726 insertions, 0 deletions

diff --git a/src/pkg/Makefile b/src/pkg/Makefile
index 44d4473fcb..b046064a6f 100644
--- a/src/pkg/Makefile
+++ b/src/pkg/Makefile
@@ -100,6 +100,7 @@ DIRS=\
 	html\
 	http\
 	http/cgi\
+	http/fcgi\
 	http/pprof\
 	http/httptest\
 	image\
diff --git a/src/pkg/http/fcgi/Makefile b/src/pkg/http/fcgi/Makefile
new file mode 100644
index 0000000000..bc01cdea9e
--- /dev/null
+++ b/src/pkg/http/fcgi/Makefile
@@ -0,0 +1,12 @@
+# 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.
+
+include ../../../Make.inc
+
+TARG=http/fcgi
+GOFILES=\
+	child.go\
+	fcgi.go\
+
+include ../../../Make.pkg
diff --git a/src/pkg/http/fcgi/child.go b/src/pkg/http/fcgi/child.go
new file mode 100644
index 0000000000..114052bee9
--- /dev/null
+++ b/src/pkg/http/fcgi/child.go
@@ -0,0 +1,328 @@
+// 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
+
+// This file implements FastCGI from the perspective of a child process.
+
+import (
+	"fmt"
+	"http"
+	"io"
+	"net"
+	"os"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// request holds the state for an in-progress request. As soon as it's complete,
+// it's converted to an http.Request.
+type request struct {
+	pw        *io.PipeWriter
+	reqId     uint16
+	params    map[string]string
+	buf       [1024]byte
+	rawParams []byte
+	keepConn  bool
+}
+
+func newRequest(reqId uint16, flags uint8) *request {
+	r := &request{
+		reqId:    reqId,
+		params:   map[string]string{},
+		keepConn: flags&flagKeepConn != 0,
+	}
+	r.rawParams = r.buf[:0]
+	return r
+}
+
+// TODO(eds): copied from http/cgi
+var skipHeader = map[string]bool{
+	"HTTP_HOST":       true,
+	"HTTP_REFERER":    true,
+	"HTTP_USER_AGENT": true,
+}
+
+// httpRequest converts r to an http.Request.
+// TODO(eds): this is very similar to http/cgi's requestFromEnvironment
+func (r *request) httpRequest(body io.ReadCloser) (*http.Request, os.Error) {
+	req := &http.Request{
+		Method:  r.params["REQUEST_METHOD"],
+		RawURL:  r.params["REQUEST_URI"],
+		Body:    body,
+		Header:  http.Header{},
+		Trailer: http.Header{},
+		Proto:   r.params["SERVER_PROTOCOL"],
+	}
+
+	var ok bool
+	req.ProtoMajor, req.ProtoMinor, ok = http.ParseHTTPVersion(req.Proto)
+	if !ok {
+		return nil, os.NewError("fcgi: invalid HTTP version")
+	}
+
+	req.Host = r.params["HTTP_HOST"]
+	req.Referer = r.params["HTTP_REFERER"]
+	req.UserAgent = r.params["HTTP_USER_AGENT"]
+
+	if lenstr := r.params["CONTENT_LENGTH"]; lenstr != "" {
+		clen, err := strconv.Atoi64(r.params["CONTENT_LENGTH"])
+		if err != nil {
+			return nil, os.NewError("fcgi: bad CONTENT_LENGTH parameter: " + lenstr)
+		}
+		req.ContentLength = clen
+	}
+
+	if req.Host != "" {
+		req.RawURL = "http://" + req.Host + r.params["REQUEST_URI"]
+		url, err := http.ParseURL(req.RawURL)
+		if err != nil {
+			return nil, os.NewError("fcgi: failed to parse host and REQUEST_URI into a URL: " + req.RawURL)
+		}
+		req.URL = url
+	}
+	if req.URL == nil {
+		req.RawURL = r.params["REQUEST_URI"]
+		url, err := http.ParseURL(req.RawURL)
+		if err != nil {
+			return nil, os.NewError("fcgi: failed to parse REQUEST_URI into a URL: " + req.RawURL)
+		}
+		req.URL = url
+	}
+
+	for key, val := range r.params {
+		if strings.HasPrefix(key, "HTTP_") && !skipHeader[key] {
+			req.Header.Add(strings.Replace(key[5:], "_", "-", -1), val)
+		}
+	}
+	return req, nil
+}
+
+// parseParams reads an encoded []byte into Params.
+func (r *request) parseParams() {
+	text := r.rawParams
+	r.rawParams = nil
+	for len(text) > 0 {
+		keyLen, n := readSize(text)
+		if n == 0 {
+			return
+		}
+		text = text[n:]
+		valLen, n := readSize(text)
+		if n == 0 {
+			return
+		}
+		text = text[n:]
+		key := readString(text, keyLen)
+		text = text[keyLen:]
+		val := readString(text, valLen)
+		text = text[valLen:]
+		r.params[key] = val
+	}
+}
+
+// response implements http.ResponseWriter.
+type response struct {
+	req         *request
+	header      http.Header
+	w           *bufWriter
+	wroteHeader bool
+}
+
+func newResponse(c *child, req *request) *response {
+	return &response{
+		req:    req,
+		header: http.Header{},
+		w:      newWriter(c.conn, typeStdout, req.reqId),
+	}
+}
+
+func (r *response) Header() http.Header {
+	return r.header
+}
+
+func (r *response) Write(data []byte) (int, os.Error) {
+	if !r.wroteHeader {
+		r.WriteHeader(http.StatusOK)
+	}
+	return r.w.Write(data)
+}
+
+func (r *response) WriteHeader(code int) {
+	if r.wroteHeader {
+		return
+	}
+	r.wroteHeader = true
+	if code == http.StatusNotModified {
+		// Must not have body.
+		r.header.Del("Content-Type")
+		r.header.Del("Content-Length")
+		r.header.Del("Transfer-Encoding")
+	} else if r.header.Get("Content-Type") == "" {
+		r.header.Set("Content-Type", "text/html; charset=utf-8")
+	}
+
+	if r.header.Get("Date") == "" {
+		r.header.Set("Date", time.UTC().Format(http.TimeFormat))
+	}
+
+	fmt.Fprintf(r.w, "Status: %d %s\r\n", code, http.StatusText(code))
+	// TODO(eds): this is duplicated in http and http/cgi
+	for k, vv := range r.header {
+		for _, v := range vv {
+			v = strings.Replace(v, "\n", "", -1)
+			v = strings.Replace(v, "\r", "", -1)
+			v = strings.TrimSpace(v)
+			fmt.Fprintf(r.w, "%s: %s\r\n", k, v)
+		}
+	}
+	r.w.WriteString("\r\n")
+}
+
+func (r *response) Flush() {
+	if !r.wroteHeader {
+		r.WriteHeader(http.StatusOK)
+	}
+	r.w.Flush()
+}
+
+func (r *response) Close() os.Error {
+	r.Flush()
+	return r.w.Close()
+}
+
+type child struct {
+	conn    *conn
+	handler http.Handler
+}
+
+func newChild(rwc net.Conn, handler http.Handler) *child {
+	return &child{newConn(rwc), handler}
+}
+
+func (c *child) serve() {
+	requests := map[uint16]*request{}
+	defer c.conn.Close()
+	var rec record
+	var br beginRequest
+	for {
+		if err := rec.read(c.conn.rwc); err != nil {
+			return
+		}
+
+		req, ok := requests[rec.h.Id]
+		if !ok && rec.h.Type != typeBeginRequest && rec.h.Type != typeGetValues {
+			// The spec says to ignore unknown request IDs.
+			continue
+		}
+		if ok && rec.h.Type == typeBeginRequest {
+			// The server is trying to begin a request with the same ID
+			// as an in-progress request. This is an error.
+			return
+		}
+
+		switch rec.h.Type {
+		case typeBeginRequest:
+			if err := br.read(rec.content()); err != nil {
+				return
+			}
+			if br.role != roleResponder {
+				c.conn.writeEndRequest(rec.h.Id, 0, statusUnknownRole)
+				break
+			}
+			requests[rec.h.Id] = newRequest(rec.h.Id, br.flags)
+		case typeParams:
+			// NOTE(eds): Technically a key-value pair can straddle the boundary
+			// between two packets. We buffer until we've received all parameters.
+			if len(rec.content()) > 0 {
+				req.rawParams = append(req.rawParams, rec.content()...)
+				break
+			}
+			req.parseParams()
+		case typeStdin:
+			content := rec.content()
+			if req.pw == nil {
+				var body io.ReadCloser
+				if len(content) > 0 {
+					// body could be an io.LimitReader, but it shouldn't matter
+					// as long as both sides are behaving.
+					body, req.pw = io.Pipe()
+				}
+				go c.serveRequest(req, body)
+			}
+			if len(content) > 0 {
+				// TODO(eds): This blocks until the handler reads from the pipe.
+				// If the handler takes a long time, it might be a problem.
+				req.pw.Write(content)
+			} else if req.pw != nil {
+				req.pw.Close()
+			}
+		case typeGetValues:
+			values := map[string]string{"FCGI_MPXS_CONNS": "1"}
+			c.conn.writePairs(0, typeGetValuesResult, values)
+		case typeData:
+			// If the filter role is implemented, read the data stream here.
+		case typeAbortRequest:
+			requests[rec.h.Id] = nil, false
+			c.conn.writeEndRequest(rec.h.Id, 0, statusRequestComplete)
+			if !req.keepConn {
+				// connection will close upon return
+				return
+			}
+		default:
+			b := make([]byte, 8)
+			b[0] = rec.h.Type
+			c.conn.writeRecord(typeUnknownType, 0, b)
+		}
+	}
+}
+
+func (c *child) serveRequest(req *request, body io.ReadCloser) {
+	r := newResponse(c, req)
+	httpReq, err := req.httpRequest(body)
+	if err != nil {
+		// there was an error reading the request
+		r.WriteHeader(http.StatusInternalServerError)
+		c.conn.writeRecord(typeStderr, req.reqId, []byte(err.String()))
+	} else {
+		c.handler.ServeHTTP(r, httpReq)
+	}
+	if body != nil {
+		body.Close()
+	}
+	r.Close()
+	c.conn.writeEndRequest(req.reqId, 0, statusRequestComplete)
+	if !req.keepConn {
+		c.conn.Close()
+	}
+}
+
+// Serve accepts incoming FastCGI connections on the listener l, creating a new
+// service thread for each. The service threads read requests and then call handler
+// to reply to them.
+// If l is nil, Serve accepts connections on stdin.
+// If handler is nil, http.DefaultServeMux is used.
+func Serve(l net.Listener, handler http.Handler) os.Error {
+	if l == nil {
+		var err os.Error
+		l, err = net.FileListener(os.Stdin)
+		if err != nil {
+			return err
+		}
+		defer l.Close()
+	}
+	if handler == nil {
+		handler = http.DefaultServeMux
+	}
+	for {
+		rw, err := l.Accept()
+		if err != nil {
+			return err
+		}
+		c := newChild(rw, handler)
+		go c.serve()
+	}
+	panic("unreachable")
+}
diff --git a/src/pkg/http/fcgi/fcgi.go b/src/pkg/http/fcgi/fcgi.go
new file mode 100644
index 0000000000..8e2e1cd3cb
--- /dev/null
+++ b/src/pkg/http/fcgi/fcgi.go
@@ -0,0 +1,271 @@
+// 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 fcgi
+
+// This file defines the raw protocol and some utilities used by the child and
+// the host.
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"io"
+	"os"
+	"sync"
+)
+
+const (
+	// Packet Types
+	typeBeginRequest = iota + 1
+	typeAbortRequest
+	typeEndRequest
+	typeParams
+	typeStdin
+	typeStdout
+	typeStderr
+	typeData
+	typeGetValues
+	typeGetValuesResult
+	typeUnknownType
+)
+
+// 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          uint8
+	Id            uint16
+	ContentLength uint16
+	PaddingLength uint8
+	Reserved      uint8
+}
+
+type beginRequest struct {
+	role     uint16
+	flags    uint8
+	reserved [5]uint8
+}
+
+func (br *beginRequest) read(content []byte) os.Error {
+	if len(content) != 8 {
+		return os.NewError("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 uint8, 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() os.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 os.Error) {
+	if err = binary.Read(r, binary.BigEndian, &rec.h); err != nil {
+		return err
+	}
+	if rec.h.Version != 1 {
+		return os.NewError("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 uint8, reqId uint16, b []byte) os.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) os.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) os.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 uint8, reqId uint16, pairs map[string]string) os.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(k)))
+		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() os.Error {
+	if err := w.Writer.Flush(); err != nil {
+		w.closer.Close()
+		return err
+	}
+	return w.closer.Close()
+}
+
+func newWriter(c *conn, recType uint8, 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 uint8
+	reqId   uint16
+}
+
+func (w *streamWriter) Write(p []byte) (int, os.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() os.Error {
+	// send empty record to close the stream
+	return w.c.writeRecord(w.recType, w.reqId, nil)
+}
diff --git a/src/pkg/http/fcgi/fcgi_test.go b/src/pkg/http/fcgi/fcgi_test.go
new file mode 100644
index 0000000000..16a6243295
--- /dev/null
+++ b/src/pkg/http/fcgi/fcgi_test.go
@@ -0,0 +1,114 @@
+// 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
+
+import (
+	"bytes"
+	"io"
+	"os"
+	"testing"
+)
+
+var sizeTests = []struct {
+	size  uint32
+	bytes []byte
+}{
+	{0, []byte{0x00}},
+	{127, []byte{0x7F}},
+	{128, []byte{0x80, 0x00, 0x00, 0x80}},
+	{1000, []byte{0x80, 0x00, 0x03, 0xE8}},
+	{33554431, []byte{0x81, 0xFF, 0xFF, 0xFF}},
+}
+
+func TestSize(t *testing.T) {
+	b := make([]byte, 4)
+	for i, test := range sizeTests {
+		n := encodeSize(b, test.size)
+		if !bytes.Equal(b[:n], test.bytes) {
+			t.Errorf("%d expected %x, encoded %x", i, test.bytes, b)
+		}
+		size, n := readSize(test.bytes)
+		if size != test.size {
+			t.Errorf("%d expected %d, read %d", i, test.size, size)
+		}
+		if len(test.bytes) != n {
+			t.Errorf("%d did not consume all the bytes", i)
+		}
+	}
+}
+
+var streamTests = []struct {
+	desc    string
+	recType uint8
+	reqId   uint16
+	content []byte
+	raw     []byte
+}{
+	{"single record", typeStdout, 1, nil,
+		[]byte{1, typeStdout, 0, 1, 0, 0, 0, 0},
+	},
+	// this data will have to be split into two records
+	{"two records", typeStdin, 300, make([]byte, 66000),
+		bytes.Join([][]byte{
+			// header for the first record
+			[]byte{1, typeStdin, 0x01, 0x2C, 0xFF, 0xFF, 1, 0},
+			make([]byte, 65536),
+			// header for the second
+			[]byte{1, typeStdin, 0x01, 0x2C, 0x01, 0xD1, 7, 0},
+			make([]byte, 472),
+			// header for the empty record
+			[]byte{1, typeStdin, 0x01, 0x2C, 0, 0, 0, 0},
+		},
+			nil),
+	},
+}
+
+type nilCloser struct {
+	io.ReadWriter
+}
+
+func (c *nilCloser) Close() os.Error { return nil }
+
+func TestStreams(t *testing.T) {
+	var rec record
+outer:
+	for _, test := range streamTests {
+		buf := bytes.NewBuffer(test.raw)
+		var content []byte
+		for buf.Len() > 0 {
+			if err := rec.read(buf); err != nil {
+				t.Errorf("%s: error reading record: %v", test.desc, err)
+				continue outer
+			}
+			content = append(content, rec.content()...)
+		}
+		if rec.h.Type != test.recType {
+			t.Errorf("%s: got type %d expected %d", test.desc, rec.h.Type, test.recType)
+			continue
+		}
+		if rec.h.Id != test.reqId {
+			t.Errorf("%s: got request ID %d expected %d", test.desc, rec.h.Id, test.reqId)
+			continue
+		}
+		if !bytes.Equal(content, test.content) {
+			t.Errorf("%s: read wrong content", test.desc)
+			continue
+		}
+		buf.Reset()
+		c := newConn(&nilCloser{buf})
+		w := newWriter(c, test.recType, test.reqId)
+		if _, err := w.Write(test.content); err != nil {
+			t.Errorf("%s: error writing record: %v", test.desc, err)
+			continue
+		}
+		if err := w.Close(); err != nil {
+			t.Errorf("%s: error closing stream: %v", test.desc, err)
+			continue
+		}
+		if !bytes.Equal(buf.Bytes(), test.raw) {
+			t.Errorf("%s: wrote wrong content", test.desc)
+		}
+	}
+}