/usr/share/gocode/src/github.com/mesos/mesos-go/messenger/decoder.go is in golang-github-mesos-mesos-go-dev 0.0.2+dfsg-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
"bufio"
"bytes"
"errors"
"io"
"net"
"net/http"
"net/textproto"
"net/url"
"strconv"
"strings"
"sync"
"sync/atomic"
"syscall"
"time"
log "github.com/golang/glog"
)
const (
DefaultReadTimeout = 5 * time.Second
DefaultWriteTimeout = 5 * time.Second
)
type decoderID int32
func (did decoderID) String() string {
return "[" + strconv.Itoa(int(did)) + "]"
}
func (did *decoderID) next() decoderID {
return decoderID(atomic.AddInt32((*int32)(did), 1))
}
var (
errHijackFailed = errors.New("failed to hijack http connection")
did decoderID // decoder ID counter
closedChan = make(chan struct{})
)
func init() {
close(closedChan)
}
type Decoder interface {
Requests() <-chan *Request
Err() <-chan error
Cancel(bool)
}
type Request struct {
*http.Request
response chan<- Response // callers that are finished with a Request should ensure that response is *always* closed, regardless of whether a Response has been written.
}
type Response struct {
code int
reason string
}
type httpDecoder struct {
req *http.Request // original request
kalive bool // keepalive
chunked bool // chunked
msg chan *Request
con net.Conn
rw *bufio.ReadWriter
errCh chan error
buf *bytes.Buffer
lrc *io.LimitedReader
shouldQuit chan struct{} // signal chan, closes upon calls to Cancel(...)
forceQuit chan struct{} // signal chan, indicates that quit is NOT graceful; closes upon Cancel(false)
cancelGuard sync.Mutex
readTimeout time.Duration
writeTimeout time.Duration
idtag string // useful for debugging
sendError func(err error) // abstraction for error handling
outCh chan *bytes.Buffer
}
// DecodeHTTP hijacks an HTTP server connection and generates mesos libprocess HTTP
// requests via the returned chan. Upon generation of an error in the error chan the
// decoder's internal goroutine will terminate. This func returns immediately.
// The caller should immediately *stop* using the ResponseWriter and Request that were
// passed as parameters; the decoder assumes full control of the HTTP transport.
func DecodeHTTP(w http.ResponseWriter, r *http.Request) Decoder {
id := did.next()
d := &httpDecoder{
msg: make(chan *Request),
errCh: make(chan error, 1),
req: r,
shouldQuit: make(chan struct{}),
forceQuit: make(chan struct{}),
readTimeout: DefaultReadTimeout,
writeTimeout: DefaultWriteTimeout,
idtag: id.String(),
outCh: make(chan *bytes.Buffer),
}
d.sendError = d.defaultSendError
go d.run(w)
return d
}
func (d *httpDecoder) Requests() <-chan *Request {
return d.msg
}
func (d *httpDecoder) Err() <-chan error {
return d.errCh
}
// Cancel the decoding process; if graceful then process pending responses before terminating
func (d *httpDecoder) Cancel(graceful bool) {
log.V(2).Infof("%scancel:%t", d.idtag, graceful)
d.cancelGuard.Lock()
defer d.cancelGuard.Unlock()
select {
case <-d.shouldQuit:
// already quitting, but perhaps gracefully?
default:
close(d.shouldQuit)
}
// allow caller to "upgrade" from a graceful cancel to a forced one
if !graceful {
select {
case <-d.forceQuit:
// already forcefully quitting
default:
close(d.forceQuit) // push it!
}
}
}
func (d *httpDecoder) run(res http.ResponseWriter) {
defer func() {
close(d.outCh)
log.V(2).Infoln(d.idtag + "run: terminating")
}()
go func() {
for buf := range d.outCh {
select {
case <-d.forceQuit:
return
default:
}
//TODO(jdef) I worry about this busy-looping
for buf.Len() > 0 {
d.tryFlushResponse(buf)
}
}
}()
var next httpState
for state := d.bootstrapState(res); state != nil; state = next {
next = state(d)
}
}
// tryFlushResponse flushes the response buffer (if not empty); returns true if flush succeeded
func (d *httpDecoder) tryFlushResponse(out *bytes.Buffer) {
log.V(2).Infof(d.idtag+"try-flush-responses: %d bytes to flush", out.Len())
// set a write deadline here so that we don't block for very long.
err := d.setWriteTimeout()
if err != nil {
// this is a problem because if we can't set the timeout then we can't guarantee
// how long a write op might block for. Log the error and skip this response.
log.Errorln("failed to set write deadline, aborting response:", err.Error())
} else {
_, err = out.WriteTo(d.rw.Writer)
if err != nil {
if neterr, ok := err.(net.Error); ok && neterr.Timeout() && out.Len() > 0 {
// we couldn't fully write before timing out, return rch and hope that
// we have better luck next time.
return
}
// we don't really know how to deal with other kinds of errors, so
// log it and skip the rest of the response.
log.Errorln("failed to write response buffer:", err.Error())
}
err = d.rw.Flush()
if err != nil {
if neterr, ok := err.(net.Error); ok && neterr.Timeout() && out.Len() > 0 {
return
}
log.Errorln("failed to flush response buffer:", err.Error())
}
}
}
// TODO(jdef) make this a func on Response, to write its contents to a *bytes.Buffer
func (d *httpDecoder) buildResponseEntity(resp *Response) *bytes.Buffer {
log.V(2).Infoln(d.idtag + "build-response-entity")
out := &bytes.Buffer{}
// generate new response buffer content and continue; buffer should have
// at least a response status-line w/ Content-Length: 0
out.WriteString("HTTP/1.1 ")
out.WriteString(strconv.Itoa(resp.code))
out.WriteString(" ")
out.WriteString(resp.reason)
out.WriteString(crlf + "Content-Length: 0" + crlf)
select {
case <-d.shouldQuit:
// this is the last request in the pipeline and we've been told to quit, so
// indicate that the server will close the connection.
out.WriteString("Connection: Close" + crlf)
default:
}
out.WriteString(crlf) // this ends the HTTP response entity
return out
}
// updateForRequest updates the chunked and kalive fields of the decoder to align
// with the header values of the request
func (d *httpDecoder) updateForRequest() {
// check "Transfer-Encoding" for "chunked"
d.chunked = false
for _, v := range d.req.Header["Transfer-Encoding"] {
if v == "chunked" {
d.chunked = true
break
}
}
if !d.chunked && d.req.ContentLength < 0 {
// strongly suspect that Go's internal net/http lib is stripping
// the Transfer-Encoding header from the initial request, so this
// workaround makes a very mesos-specific assumption: an unknown
// Content-Length indicates a chunked stream.
d.chunked = true
}
// check "Connection" for "Keep-Alive"
d.kalive = d.req.Header.Get("Connection") == "Keep-Alive"
log.V(2).Infof(d.idtag+"update-for-request: chunked %v keep-alive %v", d.chunked, d.kalive)
}
func (d *httpDecoder) readBodyContent() httpState {
log.V(2).Info(d.idtag + "read-body-content")
if d.chunked {
d.buf = &bytes.Buffer{}
return readChunkHeaderState
} else {
d.lrc = limit(d.rw.Reader, d.req.ContentLength)
d.buf = &bytes.Buffer{}
return readBodyState
}
}
const http202response = "HTTP/1.1 202 OK\r\nContent-Length: 0\r\n\r\n"
func (d *httpDecoder) generateRequest() httpState {
log.V(2).Infof(d.idtag + "generate-request")
// send a Request to msg
b := d.buf.Bytes()
rch := make(chan Response, 1)
r := &Request{
Request: &http.Request{
Method: d.req.Method,
URL: d.req.URL,
Proto: d.req.Proto,
ProtoMajor: d.req.ProtoMajor,
ProtoMinor: d.req.ProtoMinor,
Header: d.req.Header,
Close: !d.kalive,
Host: d.req.Host,
RequestURI: d.req.RequestURI,
Body: &body{bytes.NewBuffer(b)},
ContentLength: int64(len(b)),
},
response: rch,
}
select {
case d.msg <- r:
case <-d.forceQuit:
return terminateState
}
select {
case <-d.forceQuit:
return terminateState
case resp, ok := <-rch:
if ok {
// response required, so build it and ship it
out := d.buildResponseEntity(&resp)
select {
case <-d.forceQuit:
return terminateState
case d.outCh <- out:
}
}
}
if d.kalive {
d.req = &http.Request{
ContentLength: -1,
Header: make(http.Header),
}
return awaitRequestState
} else {
return gracefulTerminateState
}
}
func (d *httpDecoder) defaultSendError(err error) {
d.errCh <- err
}
type httpState func(d *httpDecoder) httpState
// terminateState forcefully shuts down the state machine
func terminateState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "terminate-state")
// closing these chans tells Decoder users that it's wrapping up
close(d.msg)
close(d.errCh)
// attempt to forcefully close the connection and signal response handlers that
// no further responses should be written
d.Cancel(false)
if d.con != nil {
d.con.Close()
}
// there is no spoon
return nil
}
func gracefulTerminateState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "gracefully-terminate-state")
// closing these chans tells Decoder users that it's wrapping up
close(d.msg)
close(d.errCh)
// gracefully terminate the connection; signal that we should flush pending
// responses before closing the connection.
d.Cancel(true)
return nil
}
func limit(r *bufio.Reader, limit int64) *io.LimitedReader {
return &io.LimitedReader{
R: r,
N: limit,
}
}
// bootstrapState expects to be called when the standard net/http lib has already
// read the initial request query line + headers from a connection. the request
// is ready to be hijacked at this point.
func (d *httpDecoder) bootstrapState(res http.ResponseWriter) httpState {
log.V(2).Infoln(d.idtag + "bootstrap-state")
d.updateForRequest()
// hijack
hj, ok := res.(http.Hijacker)
if !ok {
http.Error(res, "server does not support hijack", http.StatusInternalServerError)
d.sendError(errHijackFailed)
return terminateState
}
c, rw, err := hj.Hijack()
if err != nil {
http.Error(res, "failed to hijack the connection", http.StatusInternalServerError)
d.sendError(errHijackFailed)
return terminateState
}
d.rw = rw
d.con = c
return d.readBodyContent()
}
type body struct {
*bytes.Buffer
}
func (b *body) Close() error { return nil }
// checkTimeoutOrFail tests whether the given error is related to a timeout condition.
// returns true if the caller should advance to the returned state.
func (d *httpDecoder) checkTimeoutOrFail(err error, stateContinue httpState) (httpState, bool) {
if err != nil {
if neterr, ok := err.(net.Error); ok && neterr.Timeout() {
select {
case <-d.forceQuit:
return terminateState, true
case <-d.shouldQuit:
return gracefulTerminateState, true
default:
return stateContinue, true
}
}
d.sendError(err)
return terminateState, true
}
return nil, false
}
func (d *httpDecoder) setReadTimeoutOrFail() bool {
if d.readTimeout > 0 {
err := d.con.SetReadDeadline(time.Now().Add(d.readTimeout))
if err != nil {
d.sendError(err)
return false
}
}
return true
}
func (d *httpDecoder) setWriteTimeout() error {
if d.writeTimeout > 0 {
return d.con.SetWriteDeadline(time.Now().Add(d.writeTimeout))
}
return nil
}
func readChunkHeaderState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "read-chunk-header-state")
tr := textproto.NewReader(d.rw.Reader)
if !d.setReadTimeoutOrFail() {
return terminateState
}
hexlen, err := tr.ReadLine()
if next, ok := d.checkTimeoutOrFail(err, readChunkHeaderState); ok {
return next
}
clen, err := strconv.ParseInt(hexlen, 16, 64)
if err != nil {
d.sendError(err)
return terminateState
}
if clen == 0 {
return readEndOfChunkStreamState
}
d.lrc = limit(d.rw.Reader, clen)
return readChunkState
}
func readChunkState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag+"read-chunk-state, bytes remaining:", d.lrc.N)
if !d.setReadTimeoutOrFail() {
return terminateState
}
_, err := d.buf.ReadFrom(d.lrc)
if next, ok := d.checkTimeoutOrFail(err, readChunkState); ok {
return next
}
return readEndOfChunkState
}
const crlf = "\r\n"
func readEndOfChunkState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "read-end-of-chunk-state")
if !d.setReadTimeoutOrFail() {
return terminateState
}
b, err := d.rw.Reader.Peek(2)
if len(b) == 2 {
if string(b) == crlf {
d.rw.ReadByte()
d.rw.ReadByte()
return readChunkHeaderState
}
d.sendError(errors.New(d.idtag + "unexpected data at end-of-chunk marker"))
return terminateState
}
// less than two bytes avail
if next, ok := d.checkTimeoutOrFail(err, readEndOfChunkState); ok {
return next
}
panic("couldn't peek 2 bytes, but didn't get an error?!")
}
func readEndOfChunkStreamState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "read-end-of-chunk-stream-state")
if !d.setReadTimeoutOrFail() {
return terminateState
}
b, err := d.rw.Reader.Peek(2)
if len(b) == 2 {
if string(b) == crlf {
d.rw.ReadByte()
d.rw.ReadByte()
return d.generateRequest()
}
d.sendError(errors.New(d.idtag + "unexpected data at end-of-chunk marker"))
return terminateState
}
// less than 2 bytes avail
if next, ok := d.checkTimeoutOrFail(err, readEndOfChunkStreamState); ok {
return next
}
panic("couldn't peek 2 bytes, but didn't get an error?!")
}
func readBodyState(d *httpDecoder) httpState {
log.V(2).Infof(d.idtag+"read-body-state: %d bytes remaining", d.lrc.N)
// read remaining bytes into the buffer
var err error
if d.lrc.N > 0 {
if !d.setReadTimeoutOrFail() {
return terminateState
}
_, err = d.buf.ReadFrom(d.lrc)
}
if d.lrc.N <= 0 {
return d.generateRequest()
}
if next, ok := d.checkTimeoutOrFail(err, readBodyState); ok {
return next
}
return readBodyState
}
func isGracefulTermSignal(err error) bool {
if err == io.EOF {
return true
}
if operr, ok := err.(*net.OpError); ok {
return operr.Op == "read" && err == syscall.ECONNRESET
}
return false
}
func awaitRequestState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "await-request-state")
tr := textproto.NewReader(d.rw.Reader)
if !d.setReadTimeoutOrFail() {
return terminateState
}
requestLine, err := tr.ReadLine()
if requestLine == "" && isGracefulTermSignal(err) {
// we're actually expecting this at some point, so don't react poorly
return gracefulTerminateState
}
if next, ok := d.checkTimeoutOrFail(err, awaitRequestState); ok {
return next
}
ss := strings.SplitN(requestLine, " ", 3)
if len(ss) < 3 {
if err == io.EOF {
return gracefulTerminateState
}
d.sendError(errors.New(d.idtag + "illegal request line"))
return terminateState
}
r := d.req
r.Method = ss[0]
r.RequestURI = ss[1]
r.URL, err = url.ParseRequestURI(ss[1])
if err != nil {
d.sendError(err)
return terminateState
}
major, minor, ok := http.ParseHTTPVersion(ss[2])
if !ok {
d.sendError(errors.New(d.idtag + "malformed HTTP version"))
return terminateState
}
r.ProtoMajor = major
r.ProtoMinor = minor
r.Proto = ss[2]
return readHeaderState
}
func readHeaderState(d *httpDecoder) httpState {
log.V(2).Infoln(d.idtag + "read-header-state")
if !d.setReadTimeoutOrFail() {
return terminateState
}
r := d.req
tr := textproto.NewReader(d.rw.Reader)
h, err := tr.ReadMIMEHeader()
// merge any headers that were read successfully (before a possible error)
for k, v := range h {
if rh, exists := r.Header[k]; exists {
r.Header[k] = append(rh, v...)
} else {
r.Header[k] = v
}
log.V(2).Infoln(d.idtag+"request header", k, v)
}
if next, ok := d.checkTimeoutOrFail(err, readHeaderState); ok {
return next
}
// special headers: Host, Content-Length, Transfer-Encoding
r.Host = r.Header.Get("Host")
r.TransferEncoding = r.Header["Transfer-Encoding"]
if cl := r.Header.Get("Content-Length"); cl != "" {
l, err := strconv.ParseInt(cl, 10, 64)
if err != nil {
d.sendError(err)
return terminateState
}
if l > -1 {
r.ContentLength = l
log.V(2).Infoln(d.idtag+"set content length", r.ContentLength)
}
}
d.updateForRequest()
return d.readBodyContent()
}
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