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-rw-r--r--src/net/http/transfer.go737
1 files changed, 737 insertions, 0 deletions
diff --git a/src/net/http/transfer.go b/src/net/http/transfer.go
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index 000000000..520500330
--- /dev/null
+++ b/src/net/http/transfer.go
@@ -0,0 +1,737 @@
+// 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/internal"
+ "net/textproto"
+ "sort"
+ "strconv"
+ "strings"
+ "sync"
+)
+
+// 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
+}
+
+// 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
+ Trailer Header
+}
+
+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 = rr.Method
+ t.Body = rr.Body
+ t.BodyCloser = rr.Body
+ t.ContentLength = rr.ContentLength
+ t.Close = rr.Close
+ t.TransferEncoding = rr.TransferEncoding
+ t.Trailer = rr.Trailer
+ atLeastHTTP11 = rr.ProtoAtLeast(1, 1)
+ if t.Body != nil && len(t.TransferEncoding) == 0 && atLeastHTTP11 {
+ if t.ContentLength == 0 {
+ // Test to see if it's actually zero or just unset.
+ var buf [1]byte
+ n, rerr := io.ReadFull(t.Body, buf[:])
+ if rerr != nil && rerr != io.EOF {
+ t.ContentLength = -1
+ t.Body = &errorReader{rerr}
+ } else if n == 1 {
+ // Oh, guess there is data in this Body Reader after all.
+ // The ContentLength field just wasn't set.
+ // Stich the Body back together again, re-attaching our
+ // consumed byte.
+ t.ContentLength = -1
+ t.Body = io.MultiReader(bytes.NewReader(buf[:]), t.Body)
+ } else {
+ // Body is actually empty.
+ t.Body = nil
+ t.BodyCloser = nil
+ }
+ }
+ if t.ContentLength < 0 {
+ t.TransferEncoding = []string{"chunked"}
+ }
+ }
+ case *Response:
+ 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.Trailer = rr.Trailer
+ atLeastHTTP11 = rr.ProtoAtLeast(1, 1)
+ t.ResponseToHEAD = noBodyExpected(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
+}
+
+func noBodyExpected(requestMethod string) bool {
+ return requestMethod == "HEAD"
+}
+
+func (t *transferWriter) shouldSendContentLength() bool {
+ if chunked(t.TransferEncoding) {
+ return false
+ }
+ if t.ContentLength > 0 {
+ return true
+ }
+ // 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) {
+ return true
+ }
+
+ return false
+}
+
+func (t *transferWriter) WriteHeader(w io.Writer) error {
+ if t.Close {
+ if _, err := io.WriteString(w, "Connection: close\r\n"); err != nil {
+ return err
+ }
+ }
+
+ // 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
+ }
+ } else if chunked(t.TransferEncoding) {
+ if _, err := io.WriteString(w, "Transfer-Encoding: chunked\r\n"); err != nil {
+ return err
+ }
+ }
+
+ // 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
+ }
+ }
+ }
+
+ return nil
+}
+
+func (t *transferWriter) WriteBody(w io.Writer) error {
+ var err error
+ var ncopy int64
+
+ // Write body
+ if t.Body != nil {
+ if chunked(t.TransferEncoding) {
+ cw := internal.NewChunkedWriter(w)
+ _, err = io.Copy(cw, t.Body)
+ if err == nil {
+ err = cw.Close()
+ }
+ } else if t.ContentLength == -1 {
+ ncopy, err = io.Copy(w, t.Body)
+ } else {
+ ncopy, err = io.Copy(w, io.LimitReader(t.Body, t.ContentLength))
+ if err != nil {
+ return err
+ }
+ var nextra int64
+ nextra, err = io.Copy(ioutil.Discard, t.Body)
+ ncopy += nextra
+ }
+ if err != nil {
+ return err
+ }
+ 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)
+ }
+
+ // TODO(petar): Place trailer writer code here.
+ 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
+}
+
+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
+}
+
+// bodyAllowedForStatus reports whether a given response status code
+// permits a body. See RFC2616, section 4.4.
+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 2616 section 10.3.5: "the response MUST NOT include other entity-headers"
+ 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.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
+ 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
+ t.TransferEncoding, err = fixTransferEncoding(t.RequestMethod, t.Header)
+ 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 RFC2616, section 4.4.
+ 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 noBodyExpected(t.RequestMethod) {
+ t.Body = eofReader
+ } else {
+ t.Body = &body{src: internal.NewChunkedReader(r), hdr: msg, r: r, closing: t.Close}
+ }
+ case realLength == 0:
+ t.Body = eofReader
+ 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 = eofReader
+ }
+ }
+
+ // 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" }
+
+// Sanitize transfer encoding
+func fixTransferEncoding(requestMethod string, header Header) ([]string, error) {
+ raw, present := header["Transfer-Encoding"]
+ if !present {
+ return nil, nil
+ }
+
+ delete(header, "Transfer-Encoding")
+
+ 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 nil, &badStringError{"unsupported transfer encoding", encoding}
+ }
+ te = te[0 : len(te)+1]
+ te[len(te)-1] = encoding
+ }
+ if len(te) > 1 {
+ return nil, &badStringError{"too many transfer encodings", strings.Join(te, ",")}
+ }
+ if len(te) > 0 {
+ // Chunked encoding trumps Content-Length. See RFC 2616
+ // Section 4.4. Currently len(te) > 0 implies chunked
+ // encoding.
+ delete(header, "Content-Length")
+ return te, nil
+ }
+
+ return nil, nil
+}
+
+// Determine the expected body length, using RFC 2616 Section 4.4. 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) {
+
+ // Logic based on response type or status
+ if noBodyExpected(requestMethod) {
+ 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
+ cl := strings.TrimSpace(header.get("Content-Length"))
+ if cl != "" {
+ n, err := parseContentLength(cl)
+ if err != nil {
+ return -1, err
+ }
+ return n, nil
+ } else {
+ header.Del("Content-Length")
+ }
+
+ if !isResponse && requestMethod == "GET" {
+ // RFC 2616 doesn't explicitly permit nor forbid 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.
+ 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
+ } else if major == 1 && minor == 0 {
+ if !strings.Contains(strings.ToLower(header.get("Connection")), "keep-alive") {
+ return true
+ }
+ return false
+ } else {
+ // TODO: Should split on commas, toss surrounding white space,
+ // and check each field.
+ if strings.ToLower(header.get("Connection")) == "close" {
+ if removeCloseHeader {
+ header.Del("Connection")
+ }
+ return true
+ }
+ }
+ return false
+}
+
+// Parse the trailer header
+func fixTrailer(header Header, te []string) (Header, error) {
+ raw := header.get("Trailer")
+ if raw == "" {
+ return nil, nil
+ }
+
+ header.Del("Trailer")
+ trailer := make(Header)
+ keys := strings.Split(raw, ",")
+ for _, key := range keys {
+ key = CanonicalHeaderKey(strings.TrimSpace(key))
+ switch key {
+ case "Transfer-Encoding", "Trailer", "Content-Length":
+ return nil, &badStringError{"bad trailer key", key}
+ }
+ trailer[key] = nil
+ }
+ if len(trailer) == 0 {
+ return nil, nil
+ }
+ if !chunked(te) {
+ // Trailer and no chunking
+ return nil, ErrUnexpectedTrailer
+ }
+ 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?
+
+ mu sync.Mutex // guards closed, and calls to Read and Close
+ closed bool
+}
+
+// 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) {
+ n, err = b.src.Read(p)
+
+ if err == io.EOF {
+ // Chunked case. Read the trailer.
+ if b.hdr != nil {
+ if e := b.readTrailer(); e != nil {
+ err = e
+ }
+ 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
+ }
+ }
+
+ 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.ReadByte()
+ b.r.ReadByte()
+ 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
+ }
+}
+
+func (b *body) Close() error {
+ b.mu.Lock()
+ defer b.mu.Unlock()
+ if b.closed {
+ return nil
+ }
+ var err error
+ switch {
+ case b.hdr == nil && b.closing:
+ // no trailer and closing the connection next.
+ // no point in reading to EOF.
+ 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
+}
+
+// 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
+
+}
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