// Copyright 2009 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 http
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"net/http/httptrace"
"net/http/internal"
"net/textproto"
"reflect"
"sort"
"strconv"
"strings"
"sync"
"time"
"golang.org/x/net/http/httpguts"
)
// ErrLineTooLong is returned when reading request or response bodies
// with malformed chunked encoding.
var ErrLineTooLong = internal.ErrLineTooLong
type errorReader struct {
err error
}
func (r errorReader) Read(p []byte) (n int, err error) {
return 0, r.err
}
type byteReader struct {
b byte
done bool
}
func (br *byteReader) Read(p []byte) (n int, err error) {
if br.done {
return 0, io.EOF
}
if len(p) == 0 {
return 0, nil
}
br.done = true
p[0] = br.b
return 1, io.EOF
}
// transferWriter inspects the fields of a user-supplied Request or Response,
// sanitizes them without changing the user object and provides methods for
// writing the respective header, body and trailer in wire format.
type transferWriter struct {
Method string
Body io.Reader
BodyCloser io.Closer
ResponseToHEAD bool
ContentLength int64 // -1 means unknown, 0 means exactly none
Close bool
TransferEncoding []string
Header Header
Trailer Header
IsResponse bool
bodyReadError error // any non-EOF error from reading Body
FlushHeaders bool // flush headers to network before body
ByteReadCh chan readResult // non-nil if probeRequestBody called
}
func newTransferWriter(r interface{}) (t *transferWriter, err error) {
t = &transferWriter{}
// Extract relevant fields
atLeastHTTP11 := false
switch rr := r.(type) {
case *Request:
if rr.ContentLength != 0 && rr.Body == nil {
return nil, fmt.Errorf("http: Request.ContentLength=%d with nil Body", rr.ContentLength)
}
t.Method = valueOrDefault(rr.Method, "GET")
t.Close = rr.Close
t.TransferEncoding = rr.TransferEncoding
t.Header = rr.Header
t.Trailer = rr.Trailer
t.Body = rr.Body
t.BodyCloser = rr.Body
t.ContentLength = rr.outgoingLength()
if t.ContentLength < 0 && len(t.TransferEncoding) == 0 && t.shouldSendChunkedRequestBody() {
t.TransferEncoding = []string{"chunked"}
}
// If there's a body, conservatively flush the headers
// to any bufio.Writer we're writing to, just in case
// the server needs the headers early, before we copy
// the body and possibly block. We make an exception
// for the common standard library in-memory types,
// though, to avoid unnecessary TCP packets on the
// wire. (Issue 22088.)
if t.ContentLength != 0 && !isKnownInMemoryReader(t.Body) {
t.FlushHeaders = true
}
atLeastHTTP11 = true // Transport requests are always 1.1 or 2.0
case *Response:
t.IsResponse = true
if rr.Request != nil {
t.Method = rr.Request.Method
}
t.Body = rr.Body
t.BodyCloser = rr.Body
t.ContentLength = rr.ContentLength
t.Close = rr.Close
t.TransferEncoding = rr.TransferEncoding
t.Header = rr.Header
t.Trailer = rr.Trailer
atLeastHTTP11 = rr.ProtoAtLeast(1, 1)
t.ResponseToHEAD = noResponseBodyExpected(t.Method)
}
// Sanitize Body,ContentLength,TransferEncoding
if t.ResponseToHEAD {
t.Body = nil
if chunked(t.TransferEncoding) {
t.ContentLength = -1
}
} else {
if !atLeastHTTP11 || t.Body == nil {
t.TransferEncoding = nil
}
if chunked(t.TransferEncoding) {
t.ContentLength = -1
} else if t.Body == nil { // no chunking, no body
t.ContentLength = 0
}
}
// Sanitize Trailer
if !chunked(t.TransferEncoding) {
t.Trailer = nil
}
return t, nil
}
// shouldSendChunkedRequestBody reports whether we should try to send a
// chunked request body to the server. In particular, the case we really
// want to prevent is sending a GET or other typically-bodyless request to a
// server with a chunked body when the body has zero bytes, since GETs with
// bodies (while acceptable according to specs), even zero-byte chunked
// bodies, are approximately never seen in the wild and confuse most
// servers. See Issue 18257, as one example.
//
// The only reason we'd send such a request is if the user set the Body to a
// non-nil value (say, ioutil.NopCloser(bytes.NewReader(nil))) and didn't
// set ContentLength, or NewRequest set it to -1 (unknown), so then we assume
// there's bytes to send.
//
// This code tries to read a byte from the Request.Body in such cases to see
// whether the body actually has content (super rare) or is actually just
// a non-nil content-less ReadCloser (the more common case). In that more
// common case, we act as if their Body were nil instead, and don't send
// a body.
func (t *transferWriter) shouldSendChunkedRequestBody() bool {
// Note that t.ContentLength is the corrected content length
// from rr.outgoingLength, so 0 actually means zero, not unknown.
if t.ContentLength >= 0 || t.Body == nil { // redundant checks; caller did them
return false
}
if t.Method == "CONNECT" {
return false
}
if requestMethodUsuallyLacksBody(t.Method) {
// Only probe the Request.Body for GET/HEAD/DELETE/etc
// requests, because it's only those types of requests
// that confuse servers.
t.probeRequestBody() // adjusts t.Body, t.ContentLength
return t.Body != nil
}
// For all other request types (PUT, POST, PATCH, or anything
// made-up we've never heard of), assume it's normal and the server
// can deal with a chunked request body. Maybe we'll adjust this
// later.
return true
}
// probeRequestBody reads a byte from t.Body to see whether it's empty
// (returns io.EOF right away).
//
// But because we've had problems with this blocking users in the past
// (issue 17480) when the body is a pipe (perhaps waiting on the response
// headers before the pipe is fed data), we need to be careful and bound how
// long we wait for it. This delay will only affect users if all the following
// are true:
// * the request body blocks
// * the content length is not set (or set to -1)
// * the method doesn't usually have a body (GET, HEAD, DELETE, ...)
// * there is no transfer-encoding=chunked already set.
// In other words, this delay will not normally affect anybody, and there
// are workarounds if it does.
func (t *transferWriter) probeRequestBody() {
t.ByteReadCh = make(chan readResult, 1)
go func(body io.Reader) {
var buf [1]byte
var rres readResult
rres.n, rres.err = body.Read(buf[:])
if rres.n == 1 {
rres.b = buf[0]
}
t.ByteReadCh <- rres
}(t.Body)
timer := time.NewTimer(200 * time.Millisecond)
select {
case rres := <-t.ByteReadCh:
timer.Stop()
if rres.n == 0 && rres.err == io.EOF {
// It was empty.
t.Body = nil
t.ContentLength = 0
} else if rres.n == 1 {
if rres.err != nil {
t.Body = io.MultiReader(&byteReader{b: rres.b}, errorReader{rres.err})
} else {
t.Body = io.MultiReader(&byteReader{b: rres.b}, t.Body)
}
} else if rres.err != nil {
t.Body = errorReader{rres.err}
}
case <-timer.C:
// Too slow. Don't wait. Read it later, and keep
// assuming that this is ContentLength == -1
// (unknown), which means we'll send a
// "Transfer-Encoding: chunked" header.
t.Body = io.MultiReader(finishAsyncByteRead{t}, t.Body)
// Request that Request.Write flush the headers to the
// network before writing the body, since our body may not
// become readable until it's seen the response headers.
t.FlushHeaders = true
}
}
func noResponseBodyExpected(requestMethod string) bool {
return requestMethod == "HEAD"
}
func (t *transferWriter) shouldSendContentLength() bool {
if chunked(t.TransferEncoding) {
return false
}
if t.ContentLength > 0 {
return true
}
if t.ContentLength < 0 {
return false
}
// Many servers expect a Content-Length for these methods
if t.Method == "POST" || t.Method == "PUT" {
return true
}
if t.ContentLength == 0 && isIdentity(t.TransferEncoding) {
if t.Method == "GET" || t.Method == "HEAD" {
return false
}
return true
}
return false
}
func (t *transferWriter) writeHeader(w io.Writer, trace *httptrace.ClientTrace) error {
if t.Close && !hasToken(t.Header.get("Connection"), "close") {
if _, err := io.WriteString(w, "Connection: close\r\n"); err != nil {
return err
}
if trace != nil && trace.WroteHeaderField != nil {
trace.WroteHeaderField("Connection", []string{"close"})
}
}
// Write Content-Length and/or Transfer-Encoding whose values are a
// function of the sanitized field triple (Body, ContentLength,
// TransferEncoding)
if t.shouldSendContentLength() {
if _, err := io.WriteString(w, "Content-Length: "); err != nil {
return err
}
if _, err := io.WriteString(w, strconv.FormatInt(t.ContentLength, 10)+"\r\n"); err != nil {
return err
}
if trace != nil && trace.WroteHeaderField != nil {
trace.WroteHeaderField("Content-Length", []string{strconv.FormatInt(t.ContentLength, 10)})
}
} else if chunked(t.TransferEncoding) {
if _, err := io.WriteString(w, "Transfer-Encoding: chunked\r\n"); err != nil {
return err
}
if trace != nil && trace.WroteHeaderField != nil {
trace.WroteHeaderField("Transfer-Encoding", []string{"chunked"})
}
}
// Write Trailer header
if t.Trailer != nil {
keys := make([]string, 0, len(t.Trailer))
for k := range t.Trailer {
k = CanonicalHeaderKey(k)
switch k {
case "Transfer-Encoding", "Trailer", "Content-Length":
return &badStringError{"invalid Trailer key", k}
}
keys = append(keys, k)
}
if len(keys) > 0 {
sort.Strings(keys)
// TODO: could do better allocation-wise here, but trailers are rare,
// so being lazy for now.
if _, err := io.WriteString(w, "Trailer: "+strings.Join(keys, ",")+"\r\n"); err != nil {
return err
}
if trace != nil && trace.WroteHeaderField != nil {
trace.WroteHeaderField("Trailer", keys)
}
}
}
return nil
}
func (t *transferWriter) writeBody(w io.Writer) error {
var err error
var ncopy int64
// Write body. We "unwrap" the body first if it was wrapped in a
// nopCloser. This is to ensure that we can take advantage of
// OS-level optimizations in the event that the body is an
// *os.File.
if t.Body != nil {
var body = t.unwrapBody()
if chunked(t.TransferEncoding) {
if bw, ok := w.(*bufio.Writer); ok && !t.IsResponse {
w = &internal.FlushAfterChunkWriter{Writer: bw}
}
cw := internal.NewChunkedWriter(w)
_, err = t.doBodyCopy(cw, body)
if err == nil {
err = cw.Close()
}
} else if t.ContentLength == -1 {
dst := w
if t.Method == "CONNECT" {
dst = bufioFlushWriter{dst}
}
ncopy, err = t.doBodyCopy(dst, body)
} else {
ncopy, err = t.doBodyCopy(w, io.LimitReader(body, t.ContentLength))
if err != nil {
return err
}
var nextra int64
nextra, err = t.doBodyCopy(ioutil.Discard, body)
ncopy += nextra
}
if err != nil {
return err
}
}
if t.BodyCloser != nil {
if err := t.BodyCloser.Close(); err != nil {
return err
}
}
if !t.ResponseToHEAD && t.ContentLength != -1 && t.ContentLength != ncopy {
return fmt.Errorf("http: ContentLength=%d with Body length %d",
t.ContentLength, ncopy)
}
if chunked(t.TransferEncoding) {
// Write Trailer header
if t.Trailer != nil {
if err := t.Trailer.Write(w); err != nil {
return err
}
}
// Last chunk, empty trailer
_, err = io.WriteString(w, "\r\n")
}
return err
}
// doBodyCopy wraps a copy operation, with any resulting error also
// being saved in bodyReadError.
//
// This function is only intended for use in writeBody.
func (t *transferWriter) doBodyCopy(dst io.Writer, src io.Reader) (n int64, err error) {
n, err = io.Copy(dst, src)
if err != nil && err != io.EOF {
t.bodyReadError = err
}
return
}
// unwrapBodyReader unwraps the body's inner reader if it's a
// nopCloser. This is to ensure that body writes sourced from local
// files (*os.File types) are properly optimized.
//
// This function is only intended for use in writeBody.
func (t *transferWriter) unwrapBody() io.Reader {
if reflect.TypeOf(t.Body) == nopCloserType {
return reflect.ValueOf(t.Body).Field(0).Interface().(io.Reader)
}
return t.Body
}
type transferReader struct {
// Input
Header Header
StatusCode int
RequestMethod string
ProtoMajor int
ProtoMinor int
// Output
Body io.ReadCloser
ContentLength int64
TransferEncoding []string
Close bool
Trailer Header
}
func (t *transferReader) protoAtLeast(m, n int) bool {
return t.ProtoMajor > m || (t.ProtoMajor == m && t.ProtoMinor >= n)
}
// bodyAllowedForStatus reports whether a given response status code
// permits a body. See RFC 7230, section 3.3.
func bodyAllowedForStatus(status int) bool {
switch {
case status >= 100 && status <= 199:
return false
case status == 204:
return false
case status == 304:
return false
}
return true
}
var (
suppressedHeaders304 = []string{"Content-Type", "Content-Length", "Transfer-Encoding"}
suppressedHeadersNoBody = []string{"Content-Length", "Transfer-Encoding"}
)
func suppressedHeaders(status int) []string {
switch {
case status == 304:
// RFC 7232 section 4.1
return suppressedHeaders304
case !bodyAllowedForStatus(status):
return suppressedHeadersNoBody
}
return nil
}
// msg is *Request or *Response.
func readTransfer(msg interface{}, r *bufio.Reader) (err error) {
t := &transferReader{RequestMethod: "GET"}
// Unify input
isResponse := false
switch rr := msg.(type) {
case *Response:
t.Header = rr.Header
t.StatusCode = rr.StatusCode
t.ProtoMajor = rr.ProtoMajor
t.ProtoMinor = rr.ProtoMinor
t.Close = shouldClose(t.ProtoMajor, t.ProtoMinor, t.Header, true)
isResponse = true
if rr.Request != nil {
t.RequestMethod = rr.Request.Method
}
case *Request:
t.Header = rr.Header
t.RequestMethod = rr.Method
t.ProtoMajor = rr.ProtoMajor
t.ProtoMinor = rr.ProtoMinor
// Transfer semantics for Requests are exactly like those for
// Responses with status code 200, responding to a GET method
t.StatusCode = 200
t.Close = rr.Close
default:
panic("unexpected type")
}
// Default to HTTP/1.1
if t.ProtoMajor == 0 && t.ProtoMinor == 0 {
t.ProtoMajor, t.ProtoMinor = 1, 1
}
// Transfer encoding, content length
err = t.fixTransferEncoding()
if err != nil {
return err
}
realLength, err := fixLength(isResponse, t.StatusCode, t.RequestMethod, t.Header, t.TransferEncoding)
if err != nil {
return err
}
if isResponse && t.RequestMethod == "HEAD" {
if n, err := parseContentLength(t.Header.get("Content-Length")); err != nil {
return err
} else {
t.ContentLength = n
}
} else {
t.ContentLength = realLength
}
// Trailer
t.Trailer, err = fixTrailer(t.Header, t.TransferEncoding)
if err != nil {
return err
}
// If there is no Content-Length or chunked Transfer-Encoding on a *Response
// and the status is not 1xx, 204 or 304, then the body is unbounded.
// See RFC 7230, section 3.3.
switch msg.(type) {
case *Response:
if realLength == -1 &&
!chunked(t.TransferEncoding) &&
bodyAllowedForStatus(t.StatusCode) {
// Unbounded body.
t.Close = true
}
}
// Prepare body reader. ContentLength < 0 means chunked encoding
// or close connection when finished, since multipart is not supported yet
switch {
case chunked(t.TransferEncoding):
if noResponseBodyExpected(t.RequestMethod) || !bodyAllowedForStatus(t.StatusCode) {
t.Body = NoBody
} else {
t.Body = &body{src: internal.NewChunkedReader(r), hdr: msg, r: r, closing: t.Close}
}
case realLength == 0:
t.Body = NoBody
case realLength > 0:
t.Body = &body{src: io.LimitReader(r, realLength), closing: t.Close}
default:
// realLength < 0, i.e. "Content-Length" not mentioned in header
if t.Close {
// Close semantics (i.e. HTTP/1.0)
t.Body = &body{src: r, closing: t.Close}
} else {
// Persistent connection (i.e. HTTP/1.1)
t.Body = NoBody
}
}
// Unify output
switch rr := msg.(type) {
case *Request:
rr.Body = t.Body
rr.ContentLength = t.ContentLength
rr.TransferEncoding = t.TransferEncoding
rr.Close = t.Close
rr.Trailer = t.Trailer
case *Response:
rr.Body = t.Body
rr.ContentLength = t.ContentLength
rr.TransferEncoding = t.TransferEncoding
rr.Close = t.Close
rr.Trailer = t.Trailer
}
return nil
}
// Checks whether chunked is part of the encodings stack
func chunked(te []string) bool { return len(te) > 0 && te[0] == "chunked" }
// Checks whether the encoding is explicitly "identity".
func isIdentity(te []string) bool { return len(te) == 1 && te[0] == "identity" }
// unsupportedTEError reports unsupported transfer-encodings.
type unsupportedTEError struct {
err string
}
func (uste *unsupportedTEError) Error() string {
return uste.err
}
// isUnsupportedTEError checks if the error is of type
// unsupportedTEError. It is usually invoked with a non-nil err.
func isUnsupportedTEError(err error) bool {
_, ok := err.(*unsupportedTEError)
return ok
}
// fixTransferEncoding sanitizes t.TransferEncoding, if needed.
func (t *transferReader) fixTransferEncoding() error {
raw, present := t.Header["Transfer-Encoding"]
if !present {
return nil
}
delete(t.Header, "Transfer-Encoding")
// Issue 12785; ignore Transfer-Encoding on HTTP/1.0 requests.
if !t.protoAtLeast(1, 1) {
return nil
}
encodings := strings.Split(raw[0], ",")
te := make([]string, 0, len(encodings))
// TODO: Even though we only support "identity" and "chunked"
// encodings, the loop below is designed with foresight. One
// invariant that must be maintained is that, if present,
// chunked encoding must always come first.
for _, encoding := range encodings {
encoding = strings.ToLower(strings.TrimSpace(encoding))
// "identity" encoding is not recorded
if encoding == "identity" {
break
}
if encoding != "chunked" {
return &unsupportedTEError{fmt.Sprintf("unsupported transfer encoding: %q", encoding)}
}
te = te[0 : len(te)+1]
te[len(te)-1] = encoding
}
if len(te) > 1 {
return &badStringError{"too many transfer encodings", strings.Join(te, ",")}
}
if len(te) > 0 {
// RFC 7230 3.3.2 says "A sender MUST NOT send a
// Content-Length header field in any message that
// contains a Transfer-Encoding header field."
//
// but also:
// "If a message is received with both a
// Transfer-Encoding and a Content-Length header
// field, the Transfer-Encoding overrides the
// Content-Length. Such a message might indicate an
// attempt to perform request smuggling (Section 9.5)
// or response splitting (Section 9.4) and ought to be
// handled as an error. A sender MUST remove the
// received Content-Length field prior to forwarding
// such a message downstream."
//
// Reportedly, these appear in the wild.
delete(t.Header, "Content-Length")
t.TransferEncoding = te
return nil
}
return nil
}
// Determine the expected body length, using RFC 7230 Section 3.3. This
// function is not a method, because ultimately it should be shared by
// ReadResponse and ReadRequest.
func fixLength(isResponse bool, status int, requestMethod string, header Header, te []string) (int64, error) {
isRequest := !isResponse
contentLens := header["Content-Length"]
// Hardening against HTTP request smuggling
if len(contentLens) > 1 {
// Per RFC 7230 Section 3.3.2, prevent multiple
// Content-Length headers if they differ in value.
// If there are dups of the value, remove the dups.
// See Issue 16490.
first := strings.TrimSpace(contentLens[0])
for _, ct := range contentLens[1:] {
if first != strings.TrimSpace(ct) {
return 0, fmt.Errorf("http: message cannot contain multiple Content-Length headers; got %q", contentLens)
}
}
// deduplicate Content-Length
header.Del("Content-Length")
header.Add("Content-Length", first)
contentLens = header["Content-Length"]
}
// Logic based on response type or status
if noResponseBodyExpected(requestMethod) {
// For HTTP requests, as part of hardening against request
// smuggling (RFC 7230), don't allow a Content-Length header for
// methods which don't permit bodies. As an exception, allow
// exactly one Content-Length header if its value is "0".
if isRequest && len(contentLens) > 0 && !(len(contentLens) == 1 && contentLens[0] == "0") {
return 0, fmt.Errorf("http: method cannot contain a Content-Length; got %q", contentLens)
}
return 0, nil
}
if status/100 == 1 {
return 0, nil
}
switch status {
case 204, 304:
return 0, nil
}
// Logic based on Transfer-Encoding
if chunked(te) {
return -1, nil
}
// Logic based on Content-Length
var cl string
if len(contentLens) == 1 {
cl = strings.TrimSpace(contentLens[0])
}
if cl != "" {
n, err := parseContentLength(cl)
if err != nil {
return -1, err
}
return n, nil
}
header.Del("Content-Length")
if isRequest {
// RFC 7230 neither explicitly permits nor forbids an
// entity-body on a GET request so we permit one if
// declared, but we default to 0 here (not -1 below)
// if there's no mention of a body.
// Likewise, all other request methods are assumed to have
// no body if neither Transfer-Encoding chunked nor a
// Content-Length are set.
return 0, nil
}
// Body-EOF logic based on other methods (like closing, or chunked coding)
return -1, nil
}
// Determine whether to hang up after sending a request and body, or
// receiving a response and body
// 'header' is the request headers
func shouldClose(major, minor int, header Header, removeCloseHeader bool) bool {
if major < 1 {
return true
}
conv := header["Connection"]
hasClose := httpguts.HeaderValuesContainsToken(conv, "close")
if major == 1 && minor == 0 {
return hasClose || !httpguts.HeaderValuesContainsToken(conv, "keep-alive")
}
if hasClose && removeCloseHeader {
header.Del("Connection")
}
return hasClose
}
// Parse the trailer header
func fixTrailer(header Header, te []string) (Header, error) {
vv, ok := header["Trailer"]
if !ok {
return nil, nil
}
if !chunked(te) {
// Trailer and no chunking:
// this is an invalid use case for trailer header.
// Nevertheless, no error will be returned and we
// let users decide if this is a valid HTTP message.
// The Trailer header will be kept in Response.Header
// but not populate Response.Trailer.
// See issue #27197.
return nil, nil
}
header.Del("Trailer")
trailer := make(Header)
var err error
for _, v := range vv {
foreachHeaderElement(v, func(key string) {
key = CanonicalHeaderKey(key)
switch key {
case "Transfer-Encoding", "Trailer", "Content-Length":
if err == nil {
err = &badStringError{"bad trailer key", key}
return
}
}
trailer[key] = nil
})
}
if err != nil {
return nil, err
}
if len(trailer) == 0 {
return nil, nil
}
return trailer, nil
}
// body turns a Reader into a ReadCloser.
// Close ensures that the body has been fully read
// and then reads the trailer if necessary.
type body struct {
src io.Reader
hdr interface{} // non-nil (Response or Request) value means read trailer
r *bufio.Reader // underlying wire-format reader for the trailer
closing bool // is the connection to be closed after reading body?
doEarlyClose bool // whether Close should stop early
mu sync.Mutex // guards following, and calls to Read and Close
sawEOF bool
closed bool
earlyClose bool // Close called and we didn't read to the end of src
onHitEOF func() // if non-nil, func to call when EOF is Read
}
// ErrBodyReadAfterClose is returned when reading a Request or Response
// Body after the body has been closed. This typically happens when the body is
// read after an HTTP Handler calls WriteHeader or Write on its
// ResponseWriter.
var ErrBodyReadAfterClose = errors.New("http: invalid Read on closed Body")
func (b *body) Read(p []byte) (n int, err error) {
b.mu.Lock()
defer b.mu.Unlock()
if b.closed {
return 0, ErrBodyReadAfterClose
}
return b.readLocked(p)
}
// Must hold b.mu.
func (b *body) readLocked(p []byte) (n int, err error) {
if b.sawEOF {
return 0, io.EOF
}
n, err = b.src.Read(p)
if err == io.EOF {
b.sawEOF = true
// Chunked case. Read the trailer.
if b.hdr != nil {
if e := b.readTrailer(); e != nil {
err = e
// Something went wrong in the trailer, we must not allow any
// further reads of any kind to succeed from body, nor any
// subsequent requests on the server connection. See
// golang.org/issue/12027
b.sawEOF = false
b.closed = true
}
b.hdr = nil
} else {
// If the server declared the Content-Length, our body is a LimitedReader
// and we need to check whether this EOF arrived early.
if lr, ok := b.src.(*io.LimitedReader); ok && lr.N > 0 {
err = io.ErrUnexpectedEOF
}
}
}
// If we can return an EOF here along with the read data, do
// so. This is optional per the io.Reader contract, but doing
// so helps the HTTP transport code recycle its connection
// earlier (since it will see this EOF itself), even if the
// client doesn't do future reads or Close.
if err == nil && n > 0 {
if lr, ok := b.src.(*io.LimitedReader); ok && lr.N == 0 {
err = io.EOF
b.sawEOF = true
}
}
if b.sawEOF && b.onHitEOF != nil {
b.onHitEOF()
}
return n, err
}
var (
singleCRLF = []byte("\r\n")
doubleCRLF = []byte("\r\n\r\n")
)
func seeUpcomingDoubleCRLF(r *bufio.Reader) bool {
for peekSize := 4; ; peekSize++ {
// This loop stops when Peek returns an error,
// which it does when r's buffer has been filled.
buf, err := r.Peek(peekSize)
if bytes.HasSuffix(buf, doubleCRLF) {
return true
}
if err != nil {
break
}
}
return false
}
var errTrailerEOF = errors.New("http: unexpected EOF reading trailer")
func (b *body) readTrailer() error {
// The common case, since nobody uses trailers.
buf, err := b.r.Peek(2)
if bytes.Equal(buf, singleCRLF) {
b.r.Discard(2)
return nil
}
if len(buf) < 2 {
return errTrailerEOF
}
if err != nil {
return err
}
// Make sure there's a header terminator coming up, to prevent
// a DoS with an unbounded size Trailer. It's not easy to
// slip in a LimitReader here, as textproto.NewReader requires
// a concrete *bufio.Reader. Also, we can't get all the way
// back up to our conn's LimitedReader that *might* be backing
// this bufio.Reader. Instead, a hack: we iteratively Peek up
// to the bufio.Reader's max size, looking for a double CRLF.
// This limits the trailer to the underlying buffer size, typically 4kB.
if !seeUpcomingDoubleCRLF(b.r) {
return errors.New("http: suspiciously long trailer after chunked body")
}
hdr, err := textproto.NewReader(b.r).ReadMIMEHeader()
if err != nil {
if err == io.EOF {
return errTrailerEOF
}
return err
}
switch rr := b.hdr.(type) {
case *Request:
mergeSetHeader(&rr.Trailer, Header(hdr))
case *Response:
mergeSetHeader(&rr.Trailer, Header(hdr))
}
return nil
}
func mergeSetHeader(dst *Header, src Header) {
if *dst == nil {
*dst = src
return
}
for k, vv := range src {
(*dst)[k] = vv
}
}
// unreadDataSizeLocked returns the number of bytes of unread input.
// It returns -1 if unknown.
// b.mu must be held.
func (b *body) unreadDataSizeLocked() int64 {
if lr, ok := b.src.(*io.LimitedReader); ok {
return lr.N
}
return -1
}
func (b *body) Close() error {
b.mu.Lock()
defer b.mu.Unlock()
if b.closed {
return nil
}
var err error
switch {
case b.sawEOF:
// Already saw EOF, so no need going to look for it.
case b.hdr == nil && b.closing:
// no trailer and closing the connection next.
// no point in reading to EOF.
case b.doEarlyClose:
// Read up to maxPostHandlerReadBytes bytes of the body, looking
// for EOF (and trailers), so we can re-use this connection.
if lr, ok := b.src.(*io.LimitedReader); ok && lr.N > maxPostHandlerReadBytes {
// There was a declared Content-Length, and we have more bytes remaining
// than our maxPostHandlerReadBytes tolerance. So, give up.
b.earlyClose = true
} else {
var n int64
// Consume the body, or, which will also lead to us reading
// the trailer headers after the body, if present.
n, err = io.CopyN(ioutil.Discard, bodyLocked{b}, maxPostHandlerReadBytes)
if err == io.EOF {
err = nil
}
if n == maxPostHandlerReadBytes {
b.earlyClose = true
}
}
default:
// Fully consume the body, which will also lead to us reading
// the trailer headers after the body, if present.
_, err = io.Copy(ioutil.Discard, bodyLocked{b})
}
b.closed = true
return err
}
func (b *body) didEarlyClose() bool {
b.mu.Lock()
defer b.mu.Unlock()
return b.earlyClose
}
// bodyRemains reports whether future Read calls might
// yield data.
func (b *body) bodyRemains() bool {
b.mu.Lock()
defer b.mu.Unlock()
return !b.sawEOF
}
func (b *body) registerOnHitEOF(fn func()) {
b.mu.Lock()
defer b.mu.Unlock()
b.onHitEOF = fn
}
// bodyLocked is a io.Reader reading from a *body when its mutex is
// already held.
type bodyLocked struct {
b *body
}
func (bl bodyLocked) Read(p []byte) (n int, err error) {
if bl.b.closed {
return 0, ErrBodyReadAfterClose
}
return bl.b.readLocked(p)
}
// parseContentLength trims whitespace from s and returns -1 if no value
// is set, or the value if it's >= 0.
func parseContentLength(cl string) (int64, error) {
cl = strings.TrimSpace(cl)
if cl == "" {
return -1, nil
}
n, err := strconv.ParseInt(cl, 10, 64)
if err != nil || n < 0 {
return 0, &badStringError{"bad Content-Length", cl}
}
return n, nil
}
// finishAsyncByteRead finishes reading the 1-byte sniff
// from the ContentLength==0, Body!=nil case.
type finishAsyncByteRead struct {
tw *transferWriter
}
func (fr finishAsyncByteRead) Read(p []byte) (n int, err error) {
if len(p) == 0 {
return
}
rres := <-fr.tw.ByteReadCh
n, err = rres.n, rres.err
if n == 1 {
p[0] = rres.b
}
return
}
var nopCloserType = reflect.TypeOf(ioutil.NopCloser(nil))
// isKnownInMemoryReader reports whether r is a type known to not
// block on Read. Its caller uses this as an optional optimization to
// send fewer TCP packets.
func isKnownInMemoryReader(r io.Reader) bool {
switch r.(type) {
case *bytes.Reader, *bytes.Buffer, *strings.Reader:
return true
}
if reflect.TypeOf(r) == nopCloserType {
return isKnownInMemoryReader(reflect.ValueOf(r).Field(0).Interface().(io.Reader))
}
return false
}
// bufioFlushWriter is an io.Writer wrapper that flushes all writes
// on its wrapped writer if it's a *bufio.Writer.
type bufioFlushWriter struct{ w io.Writer }
func (fw bufioFlushWriter) Write(p []byte) (n int, err error) {
n, err = fw.w.Write(p)
if bw, ok := fw.w.(*bufio.Writer); n > 0 && ok {
ferr := bw.Flush()
if ferr != nil && err == nil {
err = ferr
}
}
return
}
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