github.com/sanprasirt/go@v0.0.0-20170607001320-a027466e4b6d/src/net/http/request.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // HTTP Request reading and parsing.
     6  
     7  package http
     8  
     9  import (
    10  	"bufio"
    11  	"bytes"
    12  	"context"
    13  	"crypto/tls"
    14  	"encoding/base64"
    15  	"errors"
    16  	"fmt"
    17  	"io"
    18  	"io/ioutil"
    19  	"mime"
    20  	"mime/multipart"
    21  	"net"
    22  	"net/http/httptrace"
    23  	"net/textproto"
    24  	"net/url"
    25  	"strconv"
    26  	"strings"
    27  	"sync"
    28  
    29  	"golang_org/x/net/idna"
    30  )
    31  
    32  const (
    33  	defaultMaxMemory = 32 << 20 // 32 MB
    34  )
    35  
    36  // ErrMissingFile is returned by FormFile when the provided file field name
    37  // is either not present in the request or not a file field.
    38  var ErrMissingFile = errors.New("http: no such file")
    39  
    40  // ProtocolError represents an HTTP protocol error.
    41  //
    42  // Deprecated: Not all errors in the http package related to protocol errors
    43  // are of type ProtocolError.
    44  type ProtocolError struct {
    45  	ErrorString string
    46  }
    47  
    48  func (pe *ProtocolError) Error() string { return pe.ErrorString }
    49  
    50  var (
    51  	// ErrNotSupported is returned by the Push method of Pusher
    52  	// implementations to indicate that HTTP/2 Push support is not
    53  	// available.
    54  	ErrNotSupported = &ProtocolError{"feature not supported"}
    55  
    56  	// ErrUnexpectedTrailer is returned by the Transport when a server
    57  	// replies with a Trailer header, but without a chunked reply.
    58  	ErrUnexpectedTrailer = &ProtocolError{"trailer header without chunked transfer encoding"}
    59  
    60  	// ErrMissingBoundary is returned by Request.MultipartReader when the
    61  	// request's Content-Type does not include a "boundary" parameter.
    62  	ErrMissingBoundary = &ProtocolError{"no multipart boundary param in Content-Type"}
    63  
    64  	// ErrNotMultipart is returned by Request.MultipartReader when the
    65  	// request's Content-Type is not multipart/form-data.
    66  	ErrNotMultipart = &ProtocolError{"request Content-Type isn't multipart/form-data"}
    67  
    68  	// Deprecated: ErrHeaderTooLong is not used.
    69  	ErrHeaderTooLong = &ProtocolError{"header too long"}
    70  	// Deprecated: ErrShortBody is not used.
    71  	ErrShortBody = &ProtocolError{"entity body too short"}
    72  	// Deprecated: ErrMissingContentLength is not used.
    73  	ErrMissingContentLength = &ProtocolError{"missing ContentLength in HEAD response"}
    74  )
    75  
    76  type badStringError struct {
    77  	what string
    78  	str  string
    79  }
    80  
    81  func (e *badStringError) Error() string { return fmt.Sprintf("%s %q", e.what, e.str) }
    82  
    83  // Headers that Request.Write handles itself and should be skipped.
    84  var reqWriteExcludeHeader = map[string]bool{
    85  	"Host":              true, // not in Header map anyway
    86  	"User-Agent":        true,
    87  	"Content-Length":    true,
    88  	"Transfer-Encoding": true,
    89  	"Trailer":           true,
    90  }
    91  
    92  // A Request represents an HTTP request received by a server
    93  // or to be sent by a client.
    94  //
    95  // The field semantics differ slightly between client and server
    96  // usage. In addition to the notes on the fields below, see the
    97  // documentation for Request.Write and RoundTripper.
    98  type Request struct {
    99  	// Method specifies the HTTP method (GET, POST, PUT, etc.).
   100  	// For client requests an empty string means GET.
   101  	Method string
   102  
   103  	// URL specifies either the URI being requested (for server
   104  	// requests) or the URL to access (for client requests).
   105  	//
   106  	// For server requests the URL is parsed from the URI
   107  	// supplied on the Request-Line as stored in RequestURI.  For
   108  	// most requests, fields other than Path and RawQuery will be
   109  	// empty. (See RFC 2616, Section 5.1.2)
   110  	//
   111  	// For client requests, the URL's Host specifies the server to
   112  	// connect to, while the Request's Host field optionally
   113  	// specifies the Host header value to send in the HTTP
   114  	// request.
   115  	URL *url.URL
   116  
   117  	// The protocol version for incoming server requests.
   118  	//
   119  	// For client requests these fields are ignored. The HTTP
   120  	// client code always uses either HTTP/1.1 or HTTP/2.
   121  	// See the docs on Transport for details.
   122  	Proto      string // "HTTP/1.0"
   123  	ProtoMajor int    // 1
   124  	ProtoMinor int    // 0
   125  
   126  	// Header contains the request header fields either received
   127  	// by the server or to be sent by the client.
   128  	//
   129  	// If a server received a request with header lines,
   130  	//
   131  	//	Host: example.com
   132  	//	accept-encoding: gzip, deflate
   133  	//	Accept-Language: en-us
   134  	//	fOO: Bar
   135  	//	foo: two
   136  	//
   137  	// then
   138  	//
   139  	//	Header = map[string][]string{
   140  	//		"Accept-Encoding": {"gzip, deflate"},
   141  	//		"Accept-Language": {"en-us"},
   142  	//		"Foo": {"Bar", "two"},
   143  	//	}
   144  	//
   145  	// For incoming requests, the Host header is promoted to the
   146  	// Request.Host field and removed from the Header map.
   147  	//
   148  	// HTTP defines that header names are case-insensitive. The
   149  	// request parser implements this by using CanonicalHeaderKey,
   150  	// making the first character and any characters following a
   151  	// hyphen uppercase and the rest lowercase.
   152  	//
   153  	// For client requests, certain headers such as Content-Length
   154  	// and Connection are automatically written when needed and
   155  	// values in Header may be ignored. See the documentation
   156  	// for the Request.Write method.
   157  	Header Header
   158  
   159  	// Body is the request's body.
   160  	//
   161  	// For client requests a nil body means the request has no
   162  	// body, such as a GET request. The HTTP Client's Transport
   163  	// is responsible for calling the Close method.
   164  	//
   165  	// For server requests the Request Body is always non-nil
   166  	// but will return EOF immediately when no body is present.
   167  	// The Server will close the request body. The ServeHTTP
   168  	// Handler does not need to.
   169  	Body io.ReadCloser
   170  
   171  	// GetBody defines an optional func to return a new copy of
   172  	// Body. It is used for client requests when a redirect requires
   173  	// reading the body more than once. Use of GetBody still
   174  	// requires setting Body.
   175  	//
   176  	// For server requests it is unused.
   177  	GetBody func() (io.ReadCloser, error)
   178  
   179  	// ContentLength records the length of the associated content.
   180  	// The value -1 indicates that the length is unknown.
   181  	// Values >= 0 indicate that the given number of bytes may
   182  	// be read from Body.
   183  	// For client requests, a value of 0 with a non-nil Body is
   184  	// also treated as unknown.
   185  	ContentLength int64
   186  
   187  	// TransferEncoding lists the transfer encodings from outermost to
   188  	// innermost. An empty list denotes the "identity" encoding.
   189  	// TransferEncoding can usually be ignored; chunked encoding is
   190  	// automatically added and removed as necessary when sending and
   191  	// receiving requests.
   192  	TransferEncoding []string
   193  
   194  	// Close indicates whether to close the connection after
   195  	// replying to this request (for servers) or after sending this
   196  	// request and reading its response (for clients).
   197  	//
   198  	// For server requests, the HTTP server handles this automatically
   199  	// and this field is not needed by Handlers.
   200  	//
   201  	// For client requests, setting this field prevents re-use of
   202  	// TCP connections between requests to the same hosts, as if
   203  	// Transport.DisableKeepAlives were set.
   204  	Close bool
   205  
   206  	// For server requests Host specifies the host on which the
   207  	// URL is sought. Per RFC 2616, this is either the value of
   208  	// the "Host" header or the host name given in the URL itself.
   209  	// It may be of the form "host:port". For international domain
   210  	// names, Host may be in Punycode or Unicode form. Use
   211  	// golang.org/x/net/idna to convert it to either format if
   212  	// needed.
   213  	//
   214  	// For client requests Host optionally overrides the Host
   215  	// header to send. If empty, the Request.Write method uses
   216  	// the value of URL.Host. Host may contain an international
   217  	// domain name.
   218  	Host string
   219  
   220  	// Form contains the parsed form data, including both the URL
   221  	// field's query parameters and the POST or PUT form data.
   222  	// This field is only available after ParseForm is called.
   223  	// The HTTP client ignores Form and uses Body instead.
   224  	Form url.Values
   225  
   226  	// PostForm contains the parsed form data from POST, PATCH,
   227  	// or PUT body parameters.
   228  	//
   229  	// This field is only available after ParseForm is called.
   230  	// The HTTP client ignores PostForm and uses Body instead.
   231  	PostForm url.Values
   232  
   233  	// MultipartForm is the parsed multipart form, including file uploads.
   234  	// This field is only available after ParseMultipartForm is called.
   235  	// The HTTP client ignores MultipartForm and uses Body instead.
   236  	MultipartForm *multipart.Form
   237  
   238  	// Trailer specifies additional headers that are sent after the request
   239  	// body.
   240  	//
   241  	// For server requests the Trailer map initially contains only the
   242  	// trailer keys, with nil values. (The client declares which trailers it
   243  	// will later send.)  While the handler is reading from Body, it must
   244  	// not reference Trailer. After reading from Body returns EOF, Trailer
   245  	// can be read again and will contain non-nil values, if they were sent
   246  	// by the client.
   247  	//
   248  	// For client requests Trailer must be initialized to a map containing
   249  	// the trailer keys to later send. The values may be nil or their final
   250  	// values. The ContentLength must be 0 or -1, to send a chunked request.
   251  	// After the HTTP request is sent the map values can be updated while
   252  	// the request body is read. Once the body returns EOF, the caller must
   253  	// not mutate Trailer.
   254  	//
   255  	// Few HTTP clients, servers, or proxies support HTTP trailers.
   256  	Trailer Header
   257  
   258  	// RemoteAddr allows HTTP servers and other software to record
   259  	// the network address that sent the request, usually for
   260  	// logging. This field is not filled in by ReadRequest and
   261  	// has no defined format. The HTTP server in this package
   262  	// sets RemoteAddr to an "IP:port" address before invoking a
   263  	// handler.
   264  	// This field is ignored by the HTTP client.
   265  	RemoteAddr string
   266  
   267  	// RequestURI is the unmodified Request-URI of the
   268  	// Request-Line (RFC 2616, Section 5.1) as sent by the client
   269  	// to a server. Usually the URL field should be used instead.
   270  	// It is an error to set this field in an HTTP client request.
   271  	RequestURI string
   272  
   273  	// TLS allows HTTP servers and other software to record
   274  	// information about the TLS connection on which the request
   275  	// was received. This field is not filled in by ReadRequest.
   276  	// The HTTP server in this package sets the field for
   277  	// TLS-enabled connections before invoking a handler;
   278  	// otherwise it leaves the field nil.
   279  	// This field is ignored by the HTTP client.
   280  	TLS *tls.ConnectionState
   281  
   282  	// Cancel is an optional channel whose closure indicates that the client
   283  	// request should be regarded as canceled. Not all implementations of
   284  	// RoundTripper may support Cancel.
   285  	//
   286  	// For server requests, this field is not applicable.
   287  	//
   288  	// Deprecated: Use the Context and WithContext methods
   289  	// instead. If a Request's Cancel field and context are both
   290  	// set, it is undefined whether Cancel is respected.
   291  	Cancel <-chan struct{}
   292  
   293  	// Response is the redirect response which caused this request
   294  	// to be created. This field is only populated during client
   295  	// redirects.
   296  	Response *Response
   297  
   298  	// ctx is either the client or server context. It should only
   299  	// be modified via copying the whole Request using WithContext.
   300  	// It is unexported to prevent people from using Context wrong
   301  	// and mutating the contexts held by callers of the same request.
   302  	ctx context.Context
   303  }
   304  
   305  // Context returns the request's context. To change the context, use
   306  // WithContext.
   307  //
   308  // The returned context is always non-nil; it defaults to the
   309  // background context.
   310  //
   311  // For outgoing client requests, the context controls cancelation.
   312  //
   313  // For incoming server requests, the context is canceled when the
   314  // client's connection closes, the request is canceled (with HTTP/2),
   315  // or when the ServeHTTP method returns.
   316  func (r *Request) Context() context.Context {
   317  	if r.ctx != nil {
   318  		return r.ctx
   319  	}
   320  	return context.Background()
   321  }
   322  
   323  // WithContext returns a shallow copy of r with its context changed
   324  // to ctx. The provided ctx must be non-nil.
   325  func (r *Request) WithContext(ctx context.Context) *Request {
   326  	if ctx == nil {
   327  		panic("nil context")
   328  	}
   329  	r2 := new(Request)
   330  	*r2 = *r
   331  	r2.ctx = ctx
   332  
   333  	// Deep copy the URL because it isn't
   334  	// a map and the URL is mutable by users
   335  	// of WithContext.
   336  	r2URL := new(url.URL)
   337  	*r2URL = *r.URL
   338  	r2.URL = r2URL
   339  
   340  	return r2
   341  }
   342  
   343  // ProtoAtLeast reports whether the HTTP protocol used
   344  // in the request is at least major.minor.
   345  func (r *Request) ProtoAtLeast(major, minor int) bool {
   346  	return r.ProtoMajor > major ||
   347  		r.ProtoMajor == major && r.ProtoMinor >= minor
   348  }
   349  
   350  // protoAtLeastOutgoing is like ProtoAtLeast, but is for outgoing
   351  // requests (see issue 18407) where these fields aren't supposed to
   352  // matter.  As a minor fix for Go 1.8, at least treat (0, 0) as
   353  // matching HTTP/1.1 or HTTP/1.0.  Only HTTP/1.1 is used.
   354  // TODO(bradfitz): ideally remove this whole method. It shouldn't be used.
   355  func (r *Request) protoAtLeastOutgoing(major, minor int) bool {
   356  	if r.ProtoMajor == 0 && r.ProtoMinor == 0 && major == 1 && minor <= 1 {
   357  		return true
   358  	}
   359  	return r.ProtoAtLeast(major, minor)
   360  }
   361  
   362  // UserAgent returns the client's User-Agent, if sent in the request.
   363  func (r *Request) UserAgent() string {
   364  	return r.Header.Get("User-Agent")
   365  }
   366  
   367  // Cookies parses and returns the HTTP cookies sent with the request.
   368  func (r *Request) Cookies() []*Cookie {
   369  	return readCookies(r.Header, "")
   370  }
   371  
   372  // ErrNoCookie is returned by Request's Cookie method when a cookie is not found.
   373  var ErrNoCookie = errors.New("http: named cookie not present")
   374  
   375  // Cookie returns the named cookie provided in the request or
   376  // ErrNoCookie if not found.
   377  // If multiple cookies match the given name, only one cookie will
   378  // be returned.
   379  func (r *Request) Cookie(name string) (*Cookie, error) {
   380  	for _, c := range readCookies(r.Header, name) {
   381  		return c, nil
   382  	}
   383  	return nil, ErrNoCookie
   384  }
   385  
   386  // AddCookie adds a cookie to the request. Per RFC 6265 section 5.4,
   387  // AddCookie does not attach more than one Cookie header field. That
   388  // means all cookies, if any, are written into the same line,
   389  // separated by semicolon.
   390  func (r *Request) AddCookie(c *Cookie) {
   391  	s := fmt.Sprintf("%s=%s", sanitizeCookieName(c.Name), sanitizeCookieValue(c.Value))
   392  	if c := r.Header.Get("Cookie"); c != "" {
   393  		r.Header.Set("Cookie", c+"; "+s)
   394  	} else {
   395  		r.Header.Set("Cookie", s)
   396  	}
   397  }
   398  
   399  // Referer returns the referring URL, if sent in the request.
   400  //
   401  // Referer is misspelled as in the request itself, a mistake from the
   402  // earliest days of HTTP.  This value can also be fetched from the
   403  // Header map as Header["Referer"]; the benefit of making it available
   404  // as a method is that the compiler can diagnose programs that use the
   405  // alternate (correct English) spelling req.Referrer() but cannot
   406  // diagnose programs that use Header["Referrer"].
   407  func (r *Request) Referer() string {
   408  	return r.Header.Get("Referer")
   409  }
   410  
   411  // multipartByReader is a sentinel value.
   412  // Its presence in Request.MultipartForm indicates that parsing of the request
   413  // body has been handed off to a MultipartReader instead of ParseMultipartFrom.
   414  var multipartByReader = &multipart.Form{
   415  	Value: make(map[string][]string),
   416  	File:  make(map[string][]*multipart.FileHeader),
   417  }
   418  
   419  // MultipartReader returns a MIME multipart reader if this is a
   420  // multipart/form-data POST request, else returns nil and an error.
   421  // Use this function instead of ParseMultipartForm to
   422  // process the request body as a stream.
   423  func (r *Request) MultipartReader() (*multipart.Reader, error) {
   424  	if r.MultipartForm == multipartByReader {
   425  		return nil, errors.New("http: MultipartReader called twice")
   426  	}
   427  	if r.MultipartForm != nil {
   428  		return nil, errors.New("http: multipart handled by ParseMultipartForm")
   429  	}
   430  	r.MultipartForm = multipartByReader
   431  	return r.multipartReader()
   432  }
   433  
   434  func (r *Request) multipartReader() (*multipart.Reader, error) {
   435  	v := r.Header.Get("Content-Type")
   436  	if v == "" {
   437  		return nil, ErrNotMultipart
   438  	}
   439  	d, params, err := mime.ParseMediaType(v)
   440  	if err != nil || d != "multipart/form-data" {
   441  		return nil, ErrNotMultipart
   442  	}
   443  	boundary, ok := params["boundary"]
   444  	if !ok {
   445  		return nil, ErrMissingBoundary
   446  	}
   447  	return multipart.NewReader(r.Body, boundary), nil
   448  }
   449  
   450  // isH2Upgrade reports whether r represents the http2 "client preface"
   451  // magic string.
   452  func (r *Request) isH2Upgrade() bool {
   453  	return r.Method == "PRI" && len(r.Header) == 0 && r.URL.Path == "*" && r.Proto == "HTTP/2.0"
   454  }
   455  
   456  // Return value if nonempty, def otherwise.
   457  func valueOrDefault(value, def string) string {
   458  	if value != "" {
   459  		return value
   460  	}
   461  	return def
   462  }
   463  
   464  // NOTE: This is not intended to reflect the actual Go version being used.
   465  // It was changed at the time of Go 1.1 release because the former User-Agent
   466  // had ended up on a blacklist for some intrusion detection systems.
   467  // See https://codereview.appspot.com/7532043.
   468  const defaultUserAgent = "Go-http-client/1.1"
   469  
   470  // Write writes an HTTP/1.1 request, which is the header and body, in wire format.
   471  // This method consults the following fields of the request:
   472  //	Host
   473  //	URL
   474  //	Method (defaults to "GET")
   475  //	Header
   476  //	ContentLength
   477  //	TransferEncoding
   478  //	Body
   479  //
   480  // If Body is present, Content-Length is <= 0 and TransferEncoding
   481  // hasn't been set to "identity", Write adds "Transfer-Encoding:
   482  // chunked" to the header. Body is closed after it is sent.
   483  func (r *Request) Write(w io.Writer) error {
   484  	return r.write(w, false, nil, nil)
   485  }
   486  
   487  // WriteProxy is like Write but writes the request in the form
   488  // expected by an HTTP proxy. In particular, WriteProxy writes the
   489  // initial Request-URI line of the request with an absolute URI, per
   490  // section 5.1.2 of RFC 2616, including the scheme and host.
   491  // In either case, WriteProxy also writes a Host header, using
   492  // either r.Host or r.URL.Host.
   493  func (r *Request) WriteProxy(w io.Writer) error {
   494  	return r.write(w, true, nil, nil)
   495  }
   496  
   497  // errMissingHost is returned by Write when there is no Host or URL present in
   498  // the Request.
   499  var errMissingHost = errors.New("http: Request.Write on Request with no Host or URL set")
   500  
   501  // extraHeaders may be nil
   502  // waitForContinue may be nil
   503  func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, waitForContinue func() bool) (err error) {
   504  	trace := httptrace.ContextClientTrace(req.Context())
   505  	if trace != nil && trace.WroteRequest != nil {
   506  		defer func() {
   507  			trace.WroteRequest(httptrace.WroteRequestInfo{
   508  				Err: err,
   509  			})
   510  		}()
   511  	}
   512  
   513  	// Find the target host. Prefer the Host: header, but if that
   514  	// is not given, use the host from the request URL.
   515  	//
   516  	// Clean the host, in case it arrives with unexpected stuff in it.
   517  	host := cleanHost(req.Host)
   518  	if host == "" {
   519  		if req.URL == nil {
   520  			return errMissingHost
   521  		}
   522  		host = cleanHost(req.URL.Host)
   523  	}
   524  
   525  	// According to RFC 6874, an HTTP client, proxy, or other
   526  	// intermediary must remove any IPv6 zone identifier attached
   527  	// to an outgoing URI.
   528  	host = removeZone(host)
   529  
   530  	ruri := req.URL.RequestURI()
   531  	if usingProxy && req.URL.Scheme != "" && req.URL.Opaque == "" {
   532  		ruri = req.URL.Scheme + "://" + host + ruri
   533  	} else if req.Method == "CONNECT" && req.URL.Path == "" {
   534  		// CONNECT requests normally give just the host and port, not a full URL.
   535  		ruri = host
   536  	}
   537  	// TODO(bradfitz): escape at least newlines in ruri?
   538  
   539  	// Wrap the writer in a bufio Writer if it's not already buffered.
   540  	// Don't always call NewWriter, as that forces a bytes.Buffer
   541  	// and other small bufio Writers to have a minimum 4k buffer
   542  	// size.
   543  	var bw *bufio.Writer
   544  	if _, ok := w.(io.ByteWriter); !ok {
   545  		bw = bufio.NewWriter(w)
   546  		w = bw
   547  	}
   548  
   549  	_, err = fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(req.Method, "GET"), ruri)
   550  	if err != nil {
   551  		return err
   552  	}
   553  
   554  	// Header lines
   555  	_, err = fmt.Fprintf(w, "Host: %s\r\n", host)
   556  	if err != nil {
   557  		return err
   558  	}
   559  
   560  	// Use the defaultUserAgent unless the Header contains one, which
   561  	// may be blank to not send the header.
   562  	userAgent := defaultUserAgent
   563  	if _, ok := req.Header["User-Agent"]; ok {
   564  		userAgent = req.Header.Get("User-Agent")
   565  	}
   566  	if userAgent != "" {
   567  		_, err = fmt.Fprintf(w, "User-Agent: %s\r\n", userAgent)
   568  		if err != nil {
   569  			return err
   570  		}
   571  	}
   572  
   573  	// Process Body,ContentLength,Close,Trailer
   574  	tw, err := newTransferWriter(req)
   575  	if err != nil {
   576  		return err
   577  	}
   578  	err = tw.WriteHeader(w)
   579  	if err != nil {
   580  		return err
   581  	}
   582  
   583  	err = req.Header.WriteSubset(w, reqWriteExcludeHeader)
   584  	if err != nil {
   585  		return err
   586  	}
   587  
   588  	if extraHeaders != nil {
   589  		err = extraHeaders.Write(w)
   590  		if err != nil {
   591  			return err
   592  		}
   593  	}
   594  
   595  	_, err = io.WriteString(w, "\r\n")
   596  	if err != nil {
   597  		return err
   598  	}
   599  
   600  	if trace != nil && trace.WroteHeaders != nil {
   601  		trace.WroteHeaders()
   602  	}
   603  
   604  	// Flush and wait for 100-continue if expected.
   605  	if waitForContinue != nil {
   606  		if bw, ok := w.(*bufio.Writer); ok {
   607  			err = bw.Flush()
   608  			if err != nil {
   609  				return err
   610  			}
   611  		}
   612  		if trace != nil && trace.Wait100Continue != nil {
   613  			trace.Wait100Continue()
   614  		}
   615  		if !waitForContinue() {
   616  			req.closeBody()
   617  			return nil
   618  		}
   619  	}
   620  
   621  	if bw, ok := w.(*bufio.Writer); ok && tw.FlushHeaders {
   622  		if err := bw.Flush(); err != nil {
   623  			return err
   624  		}
   625  	}
   626  
   627  	// Write body and trailer
   628  	err = tw.WriteBody(w)
   629  	if err != nil {
   630  		if tw.bodyReadError == err {
   631  			err = requestBodyReadError{err}
   632  		}
   633  		return err
   634  	}
   635  
   636  	if bw != nil {
   637  		return bw.Flush()
   638  	}
   639  	return nil
   640  }
   641  
   642  // requestBodyReadError wraps an error from (*Request).write to indicate
   643  // that the error came from a Read call on the Request.Body.
   644  // This error type should not escape the net/http package to users.
   645  type requestBodyReadError struct{ error }
   646  
   647  func idnaASCII(v string) (string, error) {
   648  	// TODO: Consider removing this check after verifying performance is okay.
   649  	// Right now punycode verification, length checks, context checks, and the
   650  	// permissible character tests are all omitted. It also prevents the ToASCII
   651  	// call from salvaging an invalid IDN, when possible. As a result it may be
   652  	// possible to have two IDNs that appear identical to the user where the
   653  	// ASCII-only version causes an error downstream whereas the non-ASCII
   654  	// version does not.
   655  	// Note that for correct ASCII IDNs ToASCII will only do considerably more
   656  	// work, but it will not cause an allocation.
   657  	if isASCII(v) {
   658  		return v, nil
   659  	}
   660  	return idna.Lookup.ToASCII(v)
   661  }
   662  
   663  // cleanHost cleans up the host sent in request's Host header.
   664  //
   665  // It both strips anything after '/' or ' ', and puts the value
   666  // into Punycode form, if necessary.
   667  //
   668  // Ideally we'd clean the Host header according to the spec:
   669  //   https://tools.ietf.org/html/rfc7230#section-5.4 (Host = uri-host [ ":" port ]")
   670  //   https://tools.ietf.org/html/rfc7230#section-2.7 (uri-host -> rfc3986's host)
   671  //   https://tools.ietf.org/html/rfc3986#section-3.2.2 (definition of host)
   672  // But practically, what we are trying to avoid is the situation in
   673  // issue 11206, where a malformed Host header used in the proxy context
   674  // would create a bad request. So it is enough to just truncate at the
   675  // first offending character.
   676  func cleanHost(in string) string {
   677  	if i := strings.IndexAny(in, " /"); i != -1 {
   678  		in = in[:i]
   679  	}
   680  	host, port, err := net.SplitHostPort(in)
   681  	if err != nil { // input was just a host
   682  		a, err := idnaASCII(in)
   683  		if err != nil {
   684  			return in // garbage in, garbage out
   685  		}
   686  		return a
   687  	}
   688  	a, err := idnaASCII(host)
   689  	if err != nil {
   690  		return in // garbage in, garbage out
   691  	}
   692  	return net.JoinHostPort(a, port)
   693  }
   694  
   695  // removeZone removes IPv6 zone identifier from host.
   696  // E.g., "[fe80::1%en0]:8080" to "[fe80::1]:8080"
   697  func removeZone(host string) string {
   698  	if !strings.HasPrefix(host, "[") {
   699  		return host
   700  	}
   701  	i := strings.LastIndex(host, "]")
   702  	if i < 0 {
   703  		return host
   704  	}
   705  	j := strings.LastIndex(host[:i], "%")
   706  	if j < 0 {
   707  		return host
   708  	}
   709  	return host[:j] + host[i:]
   710  }
   711  
   712  // ParseHTTPVersion parses a HTTP version string.
   713  // "HTTP/1.0" returns (1, 0, true).
   714  func ParseHTTPVersion(vers string) (major, minor int, ok bool) {
   715  	const Big = 1000000 // arbitrary upper bound
   716  	switch vers {
   717  	case "HTTP/1.1":
   718  		return 1, 1, true
   719  	case "HTTP/1.0":
   720  		return 1, 0, true
   721  	}
   722  	if !strings.HasPrefix(vers, "HTTP/") {
   723  		return 0, 0, false
   724  	}
   725  	dot := strings.Index(vers, ".")
   726  	if dot < 0 {
   727  		return 0, 0, false
   728  	}
   729  	major, err := strconv.Atoi(vers[5:dot])
   730  	if err != nil || major < 0 || major > Big {
   731  		return 0, 0, false
   732  	}
   733  	minor, err = strconv.Atoi(vers[dot+1:])
   734  	if err != nil || minor < 0 || minor > Big {
   735  		return 0, 0, false
   736  	}
   737  	return major, minor, true
   738  }
   739  
   740  func validMethod(method string) bool {
   741  	/*
   742  	     Method         = "OPTIONS"                ; Section 9.2
   743  	                    | "GET"                    ; Section 9.3
   744  	                    | "HEAD"                   ; Section 9.4
   745  	                    | "POST"                   ; Section 9.5
   746  	                    | "PUT"                    ; Section 9.6
   747  	                    | "DELETE"                 ; Section 9.7
   748  	                    | "TRACE"                  ; Section 9.8
   749  	                    | "CONNECT"                ; Section 9.9
   750  	                    | extension-method
   751  	   extension-method = token
   752  	     token          = 1*<any CHAR except CTLs or separators>
   753  	*/
   754  	return len(method) > 0 && strings.IndexFunc(method, isNotToken) == -1
   755  }
   756  
   757  // NewRequest returns a new Request given a method, URL, and optional body.
   758  //
   759  // If the provided body is also an io.Closer, the returned
   760  // Request.Body is set to body and will be closed by the Client
   761  // methods Do, Post, and PostForm, and Transport.RoundTrip.
   762  //
   763  // NewRequest returns a Request suitable for use with Client.Do or
   764  // Transport.RoundTrip. To create a request for use with testing a
   765  // Server Handler, either use the NewRequest function in the
   766  // net/http/httptest package, use ReadRequest, or manually update the
   767  // Request fields. See the Request type's documentation for the
   768  // difference between inbound and outbound request fields.
   769  //
   770  // If body is of type *bytes.Buffer, *bytes.Reader, or
   771  // *strings.Reader, the returned request's ContentLength is set to its
   772  // exact value (instead of -1), GetBody is populated (so 307 and 308
   773  // redirects can replay the body), and Body is set to NoBody if the
   774  // ContentLength is 0.
   775  func NewRequest(method, urlStr string, body io.Reader) (*Request, error) {
   776  	if method == "" {
   777  		// We document that "" means "GET" for Request.Method, and people have
   778  		// relied on that from NewRequest, so keep that working.
   779  		// We still enforce validMethod for non-empty methods.
   780  		method = "GET"
   781  	}
   782  	if !validMethod(method) {
   783  		return nil, fmt.Errorf("net/http: invalid method %q", method)
   784  	}
   785  	u, err := url.Parse(urlStr)
   786  	if err != nil {
   787  		return nil, err
   788  	}
   789  	rc, ok := body.(io.ReadCloser)
   790  	if !ok && body != nil {
   791  		rc = ioutil.NopCloser(body)
   792  	}
   793  	// The host's colon:port should be normalized. See Issue 14836.
   794  	u.Host = removeEmptyPort(u.Host)
   795  	req := &Request{
   796  		Method:     method,
   797  		URL:        u,
   798  		Proto:      "HTTP/1.1",
   799  		ProtoMajor: 1,
   800  		ProtoMinor: 1,
   801  		Header:     make(Header),
   802  		Body:       rc,
   803  		Host:       u.Host,
   804  	}
   805  	if body != nil {
   806  		switch v := body.(type) {
   807  		case *bytes.Buffer:
   808  			req.ContentLength = int64(v.Len())
   809  			buf := v.Bytes()
   810  			req.GetBody = func() (io.ReadCloser, error) {
   811  				r := bytes.NewReader(buf)
   812  				return ioutil.NopCloser(r), nil
   813  			}
   814  		case *bytes.Reader:
   815  			req.ContentLength = int64(v.Len())
   816  			snapshot := *v
   817  			req.GetBody = func() (io.ReadCloser, error) {
   818  				r := snapshot
   819  				return ioutil.NopCloser(&r), nil
   820  			}
   821  		case *strings.Reader:
   822  			req.ContentLength = int64(v.Len())
   823  			snapshot := *v
   824  			req.GetBody = func() (io.ReadCloser, error) {
   825  				r := snapshot
   826  				return ioutil.NopCloser(&r), nil
   827  			}
   828  		default:
   829  			// This is where we'd set it to -1 (at least
   830  			// if body != NoBody) to mean unknown, but
   831  			// that broke people during the Go 1.8 testing
   832  			// period. People depend on it being 0 I
   833  			// guess. Maybe retry later. See Issue 18117.
   834  		}
   835  		// For client requests, Request.ContentLength of 0
   836  		// means either actually 0, or unknown. The only way
   837  		// to explicitly say that the ContentLength is zero is
   838  		// to set the Body to nil. But turns out too much code
   839  		// depends on NewRequest returning a non-nil Body,
   840  		// so we use a well-known ReadCloser variable instead
   841  		// and have the http package also treat that sentinel
   842  		// variable to mean explicitly zero.
   843  		if req.GetBody != nil && req.ContentLength == 0 {
   844  			req.Body = NoBody
   845  			req.GetBody = func() (io.ReadCloser, error) { return NoBody, nil }
   846  		}
   847  	}
   848  
   849  	return req, nil
   850  }
   851  
   852  // BasicAuth returns the username and password provided in the request's
   853  // Authorization header, if the request uses HTTP Basic Authentication.
   854  // See RFC 2617, Section 2.
   855  func (r *Request) BasicAuth() (username, password string, ok bool) {
   856  	auth := r.Header.Get("Authorization")
   857  	if auth == "" {
   858  		return
   859  	}
   860  	return parseBasicAuth(auth)
   861  }
   862  
   863  // parseBasicAuth parses an HTTP Basic Authentication string.
   864  // "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==" returns ("Aladdin", "open sesame", true).
   865  func parseBasicAuth(auth string) (username, password string, ok bool) {
   866  	const prefix = "Basic "
   867  	if !strings.HasPrefix(auth, prefix) {
   868  		return
   869  	}
   870  	c, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
   871  	if err != nil {
   872  		return
   873  	}
   874  	cs := string(c)
   875  	s := strings.IndexByte(cs, ':')
   876  	if s < 0 {
   877  		return
   878  	}
   879  	return cs[:s], cs[s+1:], true
   880  }
   881  
   882  // SetBasicAuth sets the request's Authorization header to use HTTP
   883  // Basic Authentication with the provided username and password.
   884  //
   885  // With HTTP Basic Authentication the provided username and password
   886  // are not encrypted.
   887  func (r *Request) SetBasicAuth(username, password string) {
   888  	r.Header.Set("Authorization", "Basic "+basicAuth(username, password))
   889  }
   890  
   891  // parseRequestLine parses "GET /foo HTTP/1.1" into its three parts.
   892  func parseRequestLine(line string) (method, requestURI, proto string, ok bool) {
   893  	s1 := strings.Index(line, " ")
   894  	s2 := strings.Index(line[s1+1:], " ")
   895  	if s1 < 0 || s2 < 0 {
   896  		return
   897  	}
   898  	s2 += s1 + 1
   899  	return line[:s1], line[s1+1 : s2], line[s2+1:], true
   900  }
   901  
   902  var textprotoReaderPool sync.Pool
   903  
   904  func newTextprotoReader(br *bufio.Reader) *textproto.Reader {
   905  	if v := textprotoReaderPool.Get(); v != nil {
   906  		tr := v.(*textproto.Reader)
   907  		tr.R = br
   908  		return tr
   909  	}
   910  	return textproto.NewReader(br)
   911  }
   912  
   913  func putTextprotoReader(r *textproto.Reader) {
   914  	r.R = nil
   915  	textprotoReaderPool.Put(r)
   916  }
   917  
   918  // ReadRequest reads and parses an incoming request from b.
   919  func ReadRequest(b *bufio.Reader) (*Request, error) {
   920  	return readRequest(b, deleteHostHeader)
   921  }
   922  
   923  // Constants for readRequest's deleteHostHeader parameter.
   924  const (
   925  	deleteHostHeader = true
   926  	keepHostHeader   = false
   927  )
   928  
   929  func readRequest(b *bufio.Reader, deleteHostHeader bool) (req *Request, err error) {
   930  	tp := newTextprotoReader(b)
   931  	req = new(Request)
   932  
   933  	// First line: GET /index.html HTTP/1.0
   934  	var s string
   935  	if s, err = tp.ReadLine(); err != nil {
   936  		return nil, err
   937  	}
   938  	defer func() {
   939  		putTextprotoReader(tp)
   940  		if err == io.EOF {
   941  			err = io.ErrUnexpectedEOF
   942  		}
   943  	}()
   944  
   945  	var ok bool
   946  	req.Method, req.RequestURI, req.Proto, ok = parseRequestLine(s)
   947  	if !ok {
   948  		return nil, &badStringError{"malformed HTTP request", s}
   949  	}
   950  	if !validMethod(req.Method) {
   951  		return nil, &badStringError{"invalid method", req.Method}
   952  	}
   953  	rawurl := req.RequestURI
   954  	if req.ProtoMajor, req.ProtoMinor, ok = ParseHTTPVersion(req.Proto); !ok {
   955  		return nil, &badStringError{"malformed HTTP version", req.Proto}
   956  	}
   957  
   958  	// CONNECT requests are used two different ways, and neither uses a full URL:
   959  	// The standard use is to tunnel HTTPS through an HTTP proxy.
   960  	// It looks like "CONNECT www.google.com:443 HTTP/1.1", and the parameter is
   961  	// just the authority section of a URL. This information should go in req.URL.Host.
   962  	//
   963  	// The net/rpc package also uses CONNECT, but there the parameter is a path
   964  	// that starts with a slash. It can be parsed with the regular URL parser,
   965  	// and the path will end up in req.URL.Path, where it needs to be in order for
   966  	// RPC to work.
   967  	justAuthority := req.Method == "CONNECT" && !strings.HasPrefix(rawurl, "/")
   968  	if justAuthority {
   969  		rawurl = "http://" + rawurl
   970  	}
   971  
   972  	if req.URL, err = url.ParseRequestURI(rawurl); err != nil {
   973  		return nil, err
   974  	}
   975  
   976  	if justAuthority {
   977  		// Strip the bogus "http://" back off.
   978  		req.URL.Scheme = ""
   979  	}
   980  
   981  	// Subsequent lines: Key: value.
   982  	mimeHeader, err := tp.ReadMIMEHeader()
   983  	if err != nil {
   984  		return nil, err
   985  	}
   986  	req.Header = Header(mimeHeader)
   987  
   988  	// RFC 2616: Must treat
   989  	//	GET /index.html HTTP/1.1
   990  	//	Host: www.google.com
   991  	// and
   992  	//	GET http://www.google.com/index.html HTTP/1.1
   993  	//	Host: doesntmatter
   994  	// the same. In the second case, any Host line is ignored.
   995  	req.Host = req.URL.Host
   996  	if req.Host == "" {
   997  		req.Host = req.Header.get("Host")
   998  	}
   999  	if deleteHostHeader {
  1000  		delete(req.Header, "Host")
  1001  	}
  1002  
  1003  	fixPragmaCacheControl(req.Header)
  1004  
  1005  	req.Close = shouldClose(req.ProtoMajor, req.ProtoMinor, req.Header, false)
  1006  
  1007  	err = readTransfer(req, b)
  1008  	if err != nil {
  1009  		return nil, err
  1010  	}
  1011  
  1012  	if req.isH2Upgrade() {
  1013  		// Because it's neither chunked, nor declared:
  1014  		req.ContentLength = -1
  1015  
  1016  		// We want to give handlers a chance to hijack the
  1017  		// connection, but we need to prevent the Server from
  1018  		// dealing with the connection further if it's not
  1019  		// hijacked. Set Close to ensure that:
  1020  		req.Close = true
  1021  	}
  1022  	return req, nil
  1023  }
  1024  
  1025  // MaxBytesReader is similar to io.LimitReader but is intended for
  1026  // limiting the size of incoming request bodies. In contrast to
  1027  // io.LimitReader, MaxBytesReader's result is a ReadCloser, returns a
  1028  // non-EOF error for a Read beyond the limit, and closes the
  1029  // underlying reader when its Close method is called.
  1030  //
  1031  // MaxBytesReader prevents clients from accidentally or maliciously
  1032  // sending a large request and wasting server resources.
  1033  func MaxBytesReader(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser {
  1034  	return &maxBytesReader{w: w, r: r, n: n}
  1035  }
  1036  
  1037  type maxBytesReader struct {
  1038  	w   ResponseWriter
  1039  	r   io.ReadCloser // underlying reader
  1040  	n   int64         // max bytes remaining
  1041  	err error         // sticky error
  1042  }
  1043  
  1044  func (l *maxBytesReader) tooLarge() (n int, err error) {
  1045  	l.err = errors.New("http: request body too large")
  1046  	return 0, l.err
  1047  }
  1048  
  1049  func (l *maxBytesReader) Read(p []byte) (n int, err error) {
  1050  	if l.err != nil {
  1051  		return 0, l.err
  1052  	}
  1053  	if len(p) == 0 {
  1054  		return 0, nil
  1055  	}
  1056  	// If they asked for a 32KB byte read but only 5 bytes are
  1057  	// remaining, no need to read 32KB. 6 bytes will answer the
  1058  	// question of the whether we hit the limit or go past it.
  1059  	if int64(len(p)) > l.n+1 {
  1060  		p = p[:l.n+1]
  1061  	}
  1062  	n, err = l.r.Read(p)
  1063  
  1064  	if int64(n) <= l.n {
  1065  		l.n -= int64(n)
  1066  		l.err = err
  1067  		return n, err
  1068  	}
  1069  
  1070  	n = int(l.n)
  1071  	l.n = 0
  1072  
  1073  	// The server code and client code both use
  1074  	// maxBytesReader. This "requestTooLarge" check is
  1075  	// only used by the server code. To prevent binaries
  1076  	// which only using the HTTP Client code (such as
  1077  	// cmd/go) from also linking in the HTTP server, don't
  1078  	// use a static type assertion to the server
  1079  	// "*response" type. Check this interface instead:
  1080  	type requestTooLarger interface {
  1081  		requestTooLarge()
  1082  	}
  1083  	if res, ok := l.w.(requestTooLarger); ok {
  1084  		res.requestTooLarge()
  1085  	}
  1086  	l.err = errors.New("http: request body too large")
  1087  	return n, l.err
  1088  }
  1089  
  1090  func (l *maxBytesReader) Close() error {
  1091  	return l.r.Close()
  1092  }
  1093  
  1094  func copyValues(dst, src url.Values) {
  1095  	for k, vs := range src {
  1096  		for _, value := range vs {
  1097  			dst.Add(k, value)
  1098  		}
  1099  	}
  1100  }
  1101  
  1102  func parsePostForm(r *Request) (vs url.Values, err error) {
  1103  	if r.Body == nil {
  1104  		err = errors.New("missing form body")
  1105  		return
  1106  	}
  1107  	ct := r.Header.Get("Content-Type")
  1108  	// RFC 2616, section 7.2.1 - empty type
  1109  	//   SHOULD be treated as application/octet-stream
  1110  	if ct == "" {
  1111  		ct = "application/octet-stream"
  1112  	}
  1113  	ct, _, err = mime.ParseMediaType(ct)
  1114  	switch {
  1115  	case ct == "application/x-www-form-urlencoded":
  1116  		var reader io.Reader = r.Body
  1117  		maxFormSize := int64(1<<63 - 1)
  1118  		if _, ok := r.Body.(*maxBytesReader); !ok {
  1119  			maxFormSize = int64(10 << 20) // 10 MB is a lot of text.
  1120  			reader = io.LimitReader(r.Body, maxFormSize+1)
  1121  		}
  1122  		b, e := ioutil.ReadAll(reader)
  1123  		if e != nil {
  1124  			if err == nil {
  1125  				err = e
  1126  			}
  1127  			break
  1128  		}
  1129  		if int64(len(b)) > maxFormSize {
  1130  			err = errors.New("http: POST too large")
  1131  			return
  1132  		}
  1133  		vs, e = url.ParseQuery(string(b))
  1134  		if err == nil {
  1135  			err = e
  1136  		}
  1137  	case ct == "multipart/form-data":
  1138  		// handled by ParseMultipartForm (which is calling us, or should be)
  1139  		// TODO(bradfitz): there are too many possible
  1140  		// orders to call too many functions here.
  1141  		// Clean this up and write more tests.
  1142  		// request_test.go contains the start of this,
  1143  		// in TestParseMultipartFormOrder and others.
  1144  	}
  1145  	return
  1146  }
  1147  
  1148  // ParseForm populates r.Form and r.PostForm.
  1149  //
  1150  // For all requests, ParseForm parses the raw query from the URL and updates
  1151  // r.Form.
  1152  //
  1153  // For POST, PUT, and PATCH requests, it also parses the request body as a form
  1154  // and puts the results into both r.PostForm and r.Form. Request body parameters
  1155  // take precedence over URL query string values in r.Form.
  1156  //
  1157  // For other HTTP methods, or when the Content-Type is not
  1158  // application/x-www-form-urlencoded, the request Body is not read, and
  1159  // r.PostForm is initialized to a non-nil, empty value.
  1160  //
  1161  // If the request Body's size has not already been limited by MaxBytesReader,
  1162  // the size is capped at 10MB.
  1163  //
  1164  // ParseMultipartForm calls ParseForm automatically.
  1165  // ParseForm is idempotent.
  1166  func (r *Request) ParseForm() error {
  1167  	var err error
  1168  	if r.PostForm == nil {
  1169  		if r.Method == "POST" || r.Method == "PUT" || r.Method == "PATCH" {
  1170  			r.PostForm, err = parsePostForm(r)
  1171  		}
  1172  		if r.PostForm == nil {
  1173  			r.PostForm = make(url.Values)
  1174  		}
  1175  	}
  1176  	if r.Form == nil {
  1177  		if len(r.PostForm) > 0 {
  1178  			r.Form = make(url.Values)
  1179  			copyValues(r.Form, r.PostForm)
  1180  		}
  1181  		var newValues url.Values
  1182  		if r.URL != nil {
  1183  			var e error
  1184  			newValues, e = url.ParseQuery(r.URL.RawQuery)
  1185  			if err == nil {
  1186  				err = e
  1187  			}
  1188  		}
  1189  		if newValues == nil {
  1190  			newValues = make(url.Values)
  1191  		}
  1192  		if r.Form == nil {
  1193  			r.Form = newValues
  1194  		} else {
  1195  			copyValues(r.Form, newValues)
  1196  		}
  1197  	}
  1198  	return err
  1199  }
  1200  
  1201  // ParseMultipartForm parses a request body as multipart/form-data.
  1202  // The whole request body is parsed and up to a total of maxMemory bytes of
  1203  // its file parts are stored in memory, with the remainder stored on
  1204  // disk in temporary files.
  1205  // ParseMultipartForm calls ParseForm if necessary.
  1206  // After one call to ParseMultipartForm, subsequent calls have no effect.
  1207  func (r *Request) ParseMultipartForm(maxMemory int64) error {
  1208  	if r.MultipartForm == multipartByReader {
  1209  		return errors.New("http: multipart handled by MultipartReader")
  1210  	}
  1211  	if r.Form == nil {
  1212  		err := r.ParseForm()
  1213  		if err != nil {
  1214  			return err
  1215  		}
  1216  	}
  1217  	if r.MultipartForm != nil {
  1218  		return nil
  1219  	}
  1220  
  1221  	mr, err := r.multipartReader()
  1222  	if err != nil {
  1223  		return err
  1224  	}
  1225  
  1226  	f, err := mr.ReadForm(maxMemory)
  1227  	if err != nil {
  1228  		return err
  1229  	}
  1230  
  1231  	if r.PostForm == nil {
  1232  		r.PostForm = make(url.Values)
  1233  	}
  1234  	for k, v := range f.Value {
  1235  		r.Form[k] = append(r.Form[k], v...)
  1236  		// r.PostForm should also be populated. See Issue 9305.
  1237  		r.PostForm[k] = append(r.PostForm[k], v...)
  1238  	}
  1239  
  1240  	r.MultipartForm = f
  1241  
  1242  	return nil
  1243  }
  1244  
  1245  // FormValue returns the first value for the named component of the query.
  1246  // POST and PUT body parameters take precedence over URL query string values.
  1247  // FormValue calls ParseMultipartForm and ParseForm if necessary and ignores
  1248  // any errors returned by these functions.
  1249  // If key is not present, FormValue returns the empty string.
  1250  // To access multiple values of the same key, call ParseForm and
  1251  // then inspect Request.Form directly.
  1252  func (r *Request) FormValue(key string) string {
  1253  	if r.Form == nil {
  1254  		r.ParseMultipartForm(defaultMaxMemory)
  1255  	}
  1256  	if vs := r.Form[key]; len(vs) > 0 {
  1257  		return vs[0]
  1258  	}
  1259  	return ""
  1260  }
  1261  
  1262  // PostFormValue returns the first value for the named component of the POST
  1263  // or PUT request body. URL query parameters are ignored.
  1264  // PostFormValue calls ParseMultipartForm and ParseForm if necessary and ignores
  1265  // any errors returned by these functions.
  1266  // If key is not present, PostFormValue returns the empty string.
  1267  func (r *Request) PostFormValue(key string) string {
  1268  	if r.PostForm == nil {
  1269  		r.ParseMultipartForm(defaultMaxMemory)
  1270  	}
  1271  	if vs := r.PostForm[key]; len(vs) > 0 {
  1272  		return vs[0]
  1273  	}
  1274  	return ""
  1275  }
  1276  
  1277  // FormFile returns the first file for the provided form key.
  1278  // FormFile calls ParseMultipartForm and ParseForm if necessary.
  1279  func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, error) {
  1280  	if r.MultipartForm == multipartByReader {
  1281  		return nil, nil, errors.New("http: multipart handled by MultipartReader")
  1282  	}
  1283  	if r.MultipartForm == nil {
  1284  		err := r.ParseMultipartForm(defaultMaxMemory)
  1285  		if err != nil {
  1286  			return nil, nil, err
  1287  		}
  1288  	}
  1289  	if r.MultipartForm != nil && r.MultipartForm.File != nil {
  1290  		if fhs := r.MultipartForm.File[key]; len(fhs) > 0 {
  1291  			f, err := fhs[0].Open()
  1292  			return f, fhs[0], err
  1293  		}
  1294  	}
  1295  	return nil, nil, ErrMissingFile
  1296  }
  1297  
  1298  func (r *Request) expectsContinue() bool {
  1299  	return hasToken(r.Header.get("Expect"), "100-continue")
  1300  }
  1301  
  1302  func (r *Request) wantsHttp10KeepAlive() bool {
  1303  	if r.ProtoMajor != 1 || r.ProtoMinor != 0 {
  1304  		return false
  1305  	}
  1306  	return hasToken(r.Header.get("Connection"), "keep-alive")
  1307  }
  1308  
  1309  func (r *Request) wantsClose() bool {
  1310  	return hasToken(r.Header.get("Connection"), "close")
  1311  }
  1312  
  1313  func (r *Request) closeBody() {
  1314  	if r.Body != nil {
  1315  		r.Body.Close()
  1316  	}
  1317  }
  1318  
  1319  func (r *Request) isReplayable() bool {
  1320  	if r.Body == nil || r.Body == NoBody || r.GetBody != nil {
  1321  		switch valueOrDefault(r.Method, "GET") {
  1322  		case "GET", "HEAD", "OPTIONS", "TRACE":
  1323  			return true
  1324  		}
  1325  	}
  1326  	return false
  1327  }
  1328  
  1329  // outgoingLength reports the Content-Length of this outgoing (Client) request.
  1330  // It maps 0 into -1 (unknown) when the Body is non-nil.
  1331  func (r *Request) outgoingLength() int64 {
  1332  	if r.Body == nil || r.Body == NoBody {
  1333  		return 0
  1334  	}
  1335  	if r.ContentLength != 0 {
  1336  		return r.ContentLength
  1337  	}
  1338  	return -1
  1339  }
  1340  
  1341  // requestMethodUsuallyLacksBody reports whether the given request
  1342  // method is one that typically does not involve a request body.
  1343  // This is used by the Transport (via
  1344  // transferWriter.shouldSendChunkedRequestBody) to determine whether
  1345  // we try to test-read a byte from a non-nil Request.Body when
  1346  // Request.outgoingLength() returns -1. See the comments in
  1347  // shouldSendChunkedRequestBody.
  1348  func requestMethodUsuallyLacksBody(method string) bool {
  1349  	switch method {
  1350  	case "GET", "HEAD", "DELETE", "OPTIONS", "PROPFIND", "SEARCH":
  1351  		return true
  1352  	}
  1353  	return false
  1354  }