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Source file src/net/http/request.go

Documentation: net/http

     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  	"internal/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  	// Deprecated: ErrUnexpectedTrailer is no longer returned by
    57  	// anything in the net/http package. Callers should not
    58  	// compare errors against this variable.
    59  	ErrUnexpectedTrailer = &ProtocolError{"trailer header without chunked transfer encoding"}
    60  
    61  	// ErrMissingBoundary is returned by Request.MultipartReader when the
    62  	// request's Content-Type does not include a "boundary" parameter.
    63  	ErrMissingBoundary = &ProtocolError{"no multipart boundary param in Content-Type"}
    64  
    65  	// ErrNotMultipart is returned by Request.MultipartReader when the
    66  	// request's Content-Type is not multipart/form-data.
    67  	ErrNotMultipart = &ProtocolError{"request Content-Type isn't multipart/form-data"}
    68  
    69  	// Deprecated: ErrHeaderTooLong is no longer returned by
    70  	// anything in the net/http package. Callers should not
    71  	// compare errors against this variable.
    72  	ErrHeaderTooLong = &ProtocolError{"header too long"}
    73  
    74  	// Deprecated: ErrShortBody is no longer returned by
    75  	// anything in the net/http package. Callers should not
    76  	// compare errors against this variable.
    77  	ErrShortBody = &ProtocolError{"entity body too short"}
    78  
    79  	// Deprecated: ErrMissingContentLength is no longer returned by
    80  	// anything in the net/http package. Callers should not
    81  	// compare errors against this variable.
    82  	ErrMissingContentLength = &ProtocolError{"missing ContentLength in HEAD response"}
    83  )
    84  
    85  type badStringError struct {
    86  	what string
    87  	str  string
    88  }
    89  
    90  func (e *badStringError) Error() string { return fmt.Sprintf("%s %q", e.what, e.str) }
    91  
    92  // Headers that Request.Write handles itself and should be skipped.
    93  var reqWriteExcludeHeader = map[string]bool{
    94  	"Host":              true, // not in Header map anyway
    95  	"User-Agent":        true,
    96  	"Content-Length":    true,
    97  	"Transfer-Encoding": true,
    98  	"Trailer":           true,
    99  }
   100  
   101  // A Request represents an HTTP request received by a server
   102  // or to be sent by a client.
   103  //
   104  // The field semantics differ slightly between client and server
   105  // usage. In addition to the notes on the fields below, see the
   106  // documentation for Request.Write and RoundTripper.
   107  type Request struct {
   108  	// Method specifies the HTTP method (GET, POST, PUT, etc.).
   109  	// For client requests, an empty string means GET.
   110  	//
   111  	// Go's HTTP client does not support sending a request with
   112  	// the CONNECT method. See the documentation on Transport for
   113  	// details.
   114  	Method string
   115  
   116  	// URL specifies either the URI being requested (for server
   117  	// requests) or the URL to access (for client requests).
   118  	//
   119  	// For server requests, the URL is parsed from the URI
   120  	// supplied on the Request-Line as stored in RequestURI.  For
   121  	// most requests, fields other than Path and RawQuery will be
   122  	// empty. (See RFC 7230, Section 5.3)
   123  	//
   124  	// For client requests, the URL's Host specifies the server to
   125  	// connect to, while the Request's Host field optionally
   126  	// specifies the Host header value to send in the HTTP
   127  	// request.
   128  	URL *url.URL
   129  
   130  	// The protocol version for incoming server requests.
   131  	//
   132  	// For client requests, these fields are ignored. The HTTP
   133  	// client code always uses either HTTP/1.1 or HTTP/2.
   134  	// See the docs on Transport for details.
   135  	Proto      string // "HTTP/1.0"
   136  	ProtoMajor int    // 1
   137  	ProtoMinor int    // 0
   138  
   139  	// Header contains the request header fields either received
   140  	// by the server or to be sent by the client.
   141  	//
   142  	// If a server received a request with header lines,
   143  	//
   144  	//	Host: example.com
   145  	//	accept-encoding: gzip, deflate
   146  	//	Accept-Language: en-us
   147  	//	fOO: Bar
   148  	//	foo: two
   149  	//
   150  	// then
   151  	//
   152  	//	Header = map[string][]string{
   153  	//		"Accept-Encoding": {"gzip, deflate"},
   154  	//		"Accept-Language": {"en-us"},
   155  	//		"Foo": {"Bar", "two"},
   156  	//	}
   157  	//
   158  	// For incoming requests, the Host header is promoted to the
   159  	// Request.Host field and removed from the Header map.
   160  	//
   161  	// HTTP defines that header names are case-insensitive. The
   162  	// request parser implements this by using CanonicalHeaderKey,
   163  	// making the first character and any characters following a
   164  	// hyphen uppercase and the rest lowercase.
   165  	//
   166  	// For client requests, certain headers such as Content-Length
   167  	// and Connection are automatically written when needed and
   168  	// values in Header may be ignored. See the documentation
   169  	// for the Request.Write method.
   170  	Header Header
   171  
   172  	// Body is the request's body.
   173  	//
   174  	// For client requests, a nil body means the request has no
   175  	// body, such as a GET request. The HTTP Client's Transport
   176  	// is responsible for calling the Close method.
   177  	//
   178  	// For server requests, the Request Body is always non-nil
   179  	// but will return EOF immediately when no body is present.
   180  	// The Server will close the request body. The ServeHTTP
   181  	// Handler does not need to.
   182  	Body io.ReadCloser
   183  
   184  	// GetBody defines an optional func to return a new copy of
   185  	// Body. It is used for client requests when a redirect requires
   186  	// reading the body more than once. Use of GetBody still
   187  	// requires setting Body.
   188  	//
   189  	// For server requests, it is unused.
   190  	GetBody func() (io.ReadCloser, error)
   191  
   192  	// ContentLength records the length of the associated content.
   193  	// The value -1 indicates that the length is unknown.
   194  	// Values >= 0 indicate that the given number of bytes may
   195  	// be read from Body.
   196  	//
   197  	// For client requests, a value of 0 with a non-nil Body is
   198  	// also treated as unknown.
   199  	ContentLength int64
   200  
   201  	// TransferEncoding lists the transfer encodings from outermost to
   202  	// innermost. An empty list denotes the "identity" encoding.
   203  	// TransferEncoding can usually be ignored; chunked encoding is
   204  	// automatically added and removed as necessary when sending and
   205  	// receiving requests.
   206  	TransferEncoding []string
   207  
   208  	// Close indicates whether to close the connection after
   209  	// replying to this request (for servers) or after sending this
   210  	// request and reading its response (for clients).
   211  	//
   212  	// For server requests, the HTTP server handles this automatically
   213  	// and this field is not needed by Handlers.
   214  	//
   215  	// For client requests, setting this field prevents re-use of
   216  	// TCP connections between requests to the same hosts, as if
   217  	// Transport.DisableKeepAlives were set.
   218  	Close bool
   219  
   220  	// For server requests, Host specifies the host on which the URL
   221  	// is sought. Per RFC 7230, section 5.4, this is either the value
   222  	// of the "Host" header or the host name given in the URL itself.
   223  	// It may be of the form "host:port". For international domain
   224  	// names, Host may be in Punycode or Unicode form. Use
   225  	// golang.org/x/net/idna to convert it to either format if
   226  	// needed.
   227  	// To prevent DNS rebinding attacks, server Handlers should
   228  	// validate that the Host header has a value for which the
   229  	// Handler considers itself authoritative. The included
   230  	// ServeMux supports patterns registered to particular host
   231  	// names and thus protects its registered Handlers.
   232  	//
   233  	// For client requests, Host optionally overrides the Host
   234  	// header to send. If empty, the Request.Write method uses
   235  	// the value of URL.Host. Host may contain an international
   236  	// domain name.
   237  	Host string
   238  
   239  	// Form contains the parsed form data, including both the URL
   240  	// field's query parameters and the POST or PUT form data.
   241  	// This field is only available after ParseForm is called.
   242  	// The HTTP client ignores Form and uses Body instead.
   243  	Form url.Values
   244  
   245  	// PostForm contains the parsed form data from POST, PATCH,
   246  	// or PUT body parameters.
   247  	//
   248  	// This field is only available after ParseForm is called.
   249  	// The HTTP client ignores PostForm and uses Body instead.
   250  	PostForm url.Values
   251  
   252  	// MultipartForm is the parsed multipart form, including file uploads.
   253  	// This field is only available after ParseMultipartForm is called.
   254  	// The HTTP client ignores MultipartForm and uses Body instead.
   255  	MultipartForm *multipart.Form
   256  
   257  	// Trailer specifies additional headers that are sent after the request
   258  	// body.
   259  	//
   260  	// For server requests, the Trailer map initially contains only the
   261  	// trailer keys, with nil values. (The client declares which trailers it
   262  	// will later send.)  While the handler is reading from Body, it must
   263  	// not reference Trailer. After reading from Body returns EOF, Trailer
   264  	// can be read again and will contain non-nil values, if they were sent
   265  	// by the client.
   266  	//
   267  	// For client requests, Trailer must be initialized to a map containing
   268  	// the trailer keys to later send. The values may be nil or their final
   269  	// values. The ContentLength must be 0 or -1, to send a chunked request.
   270  	// After the HTTP request is sent the map values can be updated while
   271  	// the request body is read. Once the body returns EOF, the caller must
   272  	// not mutate Trailer.
   273  	//
   274  	// Few HTTP clients, servers, or proxies support HTTP trailers.
   275  	Trailer Header
   276  
   277  	// RemoteAddr allows HTTP servers and other software to record
   278  	// the network address that sent the request, usually for
   279  	// logging. This field is not filled in by ReadRequest and
   280  	// has no defined format. The HTTP server in this package
   281  	// sets RemoteAddr to an "IP:port" address before invoking a
   282  	// handler.
   283  	// This field is ignored by the HTTP client.
   284  	RemoteAddr string
   285  
   286  	// RequestURI is the unmodified request-target of the
   287  	// Request-Line (RFC 7230, Section 3.1.1) as sent by the client
   288  	// to a server. Usually the URL field should be used instead.
   289  	// It is an error to set this field in an HTTP client request.
   290  	RequestURI string
   291  
   292  	// TLS allows HTTP servers and other software to record
   293  	// information about the TLS connection on which the request
   294  	// was received. This field is not filled in by ReadRequest.
   295  	// The HTTP server in this package sets the field for
   296  	// TLS-enabled connections before invoking a handler;
   297  	// otherwise it leaves the field nil.
   298  	// This field is ignored by the HTTP client.
   299  	TLS *tls.ConnectionState
   300  
   301  	// Cancel is an optional channel whose closure indicates that the client
   302  	// request should be regarded as canceled. Not all implementations of
   303  	// RoundTripper may support Cancel.
   304  	//
   305  	// For server requests, this field is not applicable.
   306  	//
   307  	// Deprecated: Use the Context and WithContext methods
   308  	// instead. If a Request's Cancel field and context are both
   309  	// set, it is undefined whether Cancel is respected.
   310  	Cancel <-chan struct{}
   311  
   312  	// Response is the redirect response which caused this request
   313  	// to be created. This field is only populated during client
   314  	// redirects.
   315  	Response *Response
   316  
   317  	// ctx is either the client or server context. It should only
   318  	// be modified via copying the whole Request using WithContext.
   319  	// It is unexported to prevent people from using Context wrong
   320  	// and mutating the contexts held by callers of the same request.
   321  	ctx context.Context
   322  }
   323  
   324  // Context returns the request's context. To change the context, use
   325  // WithContext.
   326  //
   327  // The returned context is always non-nil; it defaults to the
   328  // background context.
   329  //
   330  // For outgoing client requests, the context controls cancelation.
   331  //
   332  // For incoming server requests, the context is canceled when the
   333  // client's connection closes, the request is canceled (with HTTP/2),
   334  // or when the ServeHTTP method returns.
   335  func (r *Request) Context() context.Context {
   336  	if r.ctx != nil {
   337  		return r.ctx
   338  	}
   339  	return context.Background()
   340  }
   341  
   342  // WithContext returns a shallow copy of r with its context changed
   343  // to ctx. The provided ctx must be non-nil.
   344  //
   345  // For outgoing client request, the context controls the entire
   346  // lifetime of a request and its response: obtaining a connection,
   347  // sending the request, and reading the response headers and body.
   348  func (r *Request) WithContext(ctx context.Context) *Request {
   349  	if ctx == nil {
   350  		panic("nil context")
   351  	}
   352  	r2 := new(Request)
   353  	*r2 = *r
   354  	r2.ctx = ctx
   355  
   356  	// Deep copy the URL because it isn't
   357  	// a map and the URL is mutable by users
   358  	// of WithContext.
   359  	if r.URL != nil {
   360  		r2URL := new(url.URL)
   361  		*r2URL = *r.URL
   362  		r2.URL = r2URL
   363  	}
   364  
   365  	return r2
   366  }
   367  
   368  // ProtoAtLeast reports whether the HTTP protocol used
   369  // in the request is at least major.minor.
   370  func (r *Request) ProtoAtLeast(major, minor int) bool {
   371  	return r.ProtoMajor > major ||
   372  		r.ProtoMajor == major && r.ProtoMinor >= minor
   373  }
   374  
   375  // UserAgent returns the client's User-Agent, if sent in the request.
   376  func (r *Request) UserAgent() string {
   377  	return r.Header.Get("User-Agent")
   378  }
   379  
   380  // Cookies parses and returns the HTTP cookies sent with the request.
   381  func (r *Request) Cookies() []*Cookie {
   382  	return readCookies(r.Header, "")
   383  }
   384  
   385  // ErrNoCookie is returned by Request's Cookie method when a cookie is not found.
   386  var ErrNoCookie = errors.New("http: named cookie not present")
   387  
   388  // Cookie returns the named cookie provided in the request or
   389  // ErrNoCookie if not found.
   390  // If multiple cookies match the given name, only one cookie will
   391  // be returned.
   392  func (r *Request) Cookie(name string) (*Cookie, error) {
   393  	for _, c := range readCookies(r.Header, name) {
   394  		return c, nil
   395  	}
   396  	return nil, ErrNoCookie
   397  }
   398  
   399  // AddCookie adds a cookie to the request. Per RFC 6265 section 5.4,
   400  // AddCookie does not attach more than one Cookie header field. That
   401  // means all cookies, if any, are written into the same line,
   402  // separated by semicolon.
   403  func (r *Request) AddCookie(c *Cookie) {
   404  	s := fmt.Sprintf("%s=%s", sanitizeCookieName(c.Name), sanitizeCookieValue(c.Value))
   405  	if c := r.Header.Get("Cookie"); c != "" {
   406  		r.Header.Set("Cookie", c+"; "+s)
   407  	} else {
   408  		r.Header.Set("Cookie", s)
   409  	}
   410  }
   411  
   412  // Referer returns the referring URL, if sent in the request.
   413  //
   414  // Referer is misspelled as in the request itself, a mistake from the
   415  // earliest days of HTTP.  This value can also be fetched from the
   416  // Header map as Header["Referer"]; the benefit of making it available
   417  // as a method is that the compiler can diagnose programs that use the
   418  // alternate (correct English) spelling req.Referrer() but cannot
   419  // diagnose programs that use Header["Referrer"].
   420  func (r *Request) Referer() string {
   421  	return r.Header.Get("Referer")
   422  }
   423  
   424  // multipartByReader is a sentinel value.
   425  // Its presence in Request.MultipartForm indicates that parsing of the request
   426  // body has been handed off to a MultipartReader instead of ParseMultipartFrom.
   427  var multipartByReader = &multipart.Form{
   428  	Value: make(map[string][]string),
   429  	File:  make(map[string][]*multipart.FileHeader),
   430  }
   431  
   432  // MultipartReader returns a MIME multipart reader if this is a
   433  // multipart/form-data or a multipart/mixed POST request, else returns nil and an error.
   434  // Use this function instead of ParseMultipartForm to
   435  // process the request body as a stream.
   436  func (r *Request) MultipartReader() (*multipart.Reader, error) {
   437  	if r.MultipartForm == multipartByReader {
   438  		return nil, errors.New("http: MultipartReader called twice")
   439  	}
   440  	if r.MultipartForm != nil {
   441  		return nil, errors.New("http: multipart handled by ParseMultipartForm")
   442  	}
   443  	r.MultipartForm = multipartByReader
   444  	return r.multipartReader(true)
   445  }
   446  
   447  func (r *Request) multipartReader(allowMixed bool) (*multipart.Reader, error) {
   448  	v := r.Header.Get("Content-Type")
   449  	if v == "" {
   450  		return nil, ErrNotMultipart
   451  	}
   452  	d, params, err := mime.ParseMediaType(v)
   453  	if err != nil || !(d == "multipart/form-data" || allowMixed && d == "multipart/mixed") {
   454  		return nil, ErrNotMultipart
   455  	}
   456  	boundary, ok := params["boundary"]
   457  	if !ok {
   458  		return nil, ErrMissingBoundary
   459  	}
   460  	return multipart.NewReader(r.Body, boundary), nil
   461  }
   462  
   463  // isH2Upgrade reports whether r represents the http2 "client preface"
   464  // magic string.
   465  func (r *Request) isH2Upgrade() bool {
   466  	return r.Method == "PRI" && len(r.Header) == 0 && r.URL.Path == "*" && r.Proto == "HTTP/2.0"
   467  }
   468  
   469  // Return value if nonempty, def otherwise.
   470  func valueOrDefault(value, def string) string {
   471  	if value != "" {
   472  		return value
   473  	}
   474  	return def
   475  }
   476  
   477  // NOTE: This is not intended to reflect the actual Go version being used.
   478  // It was changed at the time of Go 1.1 release because the former User-Agent
   479  // had ended up on a blacklist for some intrusion detection systems.
   480  // See https://codereview.appspot.com/7532043.
   481  const defaultUserAgent = "Go-http-client/1.1"
   482  
   483  // Write writes an HTTP/1.1 request, which is the header and body, in wire format.
   484  // This method consults the following fields of the request:
   485  //	Host
   486  //	URL
   487  //	Method (defaults to "GET")
   488  //	Header
   489  //	ContentLength
   490  //	TransferEncoding
   491  //	Body
   492  //
   493  // If Body is present, Content-Length is <= 0 and TransferEncoding
   494  // hasn't been set to "identity", Write adds "Transfer-Encoding:
   495  // chunked" to the header. Body is closed after it is sent.
   496  func (r *Request) Write(w io.Writer) error {
   497  	return r.write(w, false, nil, nil)
   498  }
   499  
   500  // WriteProxy is like Write but writes the request in the form
   501  // expected by an HTTP proxy. In particular, WriteProxy writes the
   502  // initial Request-URI line of the request with an absolute URI, per
   503  // section 5.3 of RFC 7230, including the scheme and host.
   504  // In either case, WriteProxy also writes a Host header, using
   505  // either r.Host or r.URL.Host.
   506  func (r *Request) WriteProxy(w io.Writer) error {
   507  	return r.write(w, true, nil, nil)
   508  }
   509  
   510  // errMissingHost is returned by Write when there is no Host or URL present in
   511  // the Request.
   512  var errMissingHost = errors.New("http: Request.Write on Request with no Host or URL set")
   513  
   514  // extraHeaders may be nil
   515  // waitForContinue may be nil
   516  func (r *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, waitForContinue func() bool) (err error) {
   517  	trace := httptrace.ContextClientTrace(r.Context())
   518  	if trace != nil && trace.WroteRequest != nil {
   519  		defer func() {
   520  			trace.WroteRequest(httptrace.WroteRequestInfo{
   521  				Err: err,
   522  			})
   523  		}()
   524  	}
   525  
   526  	// Find the target host. Prefer the Host: header, but if that
   527  	// is not given, use the host from the request URL.
   528  	//
   529  	// Clean the host, in case it arrives with unexpected stuff in it.
   530  	host := cleanHost(r.Host)
   531  	if host == "" {
   532  		if r.URL == nil {
   533  			return errMissingHost
   534  		}
   535  		host = cleanHost(r.URL.Host)
   536  	}
   537  
   538  	// According to RFC 6874, an HTTP client, proxy, or other
   539  	// intermediary must remove any IPv6 zone identifier attached
   540  	// to an outgoing URI.
   541  	host = removeZone(host)
   542  
   543  	ruri := r.URL.RequestURI()
   544  	if usingProxy && r.URL.Scheme != "" && r.URL.Opaque == "" {
   545  		ruri = r.URL.Scheme + "://" + host + ruri
   546  	} else if r.Method == "CONNECT" && r.URL.Path == "" {
   547  		// CONNECT requests normally give just the host and port, not a full URL.
   548  		ruri = host
   549  		if r.URL.Opaque != "" {
   550  			ruri = r.URL.Opaque
   551  		}
   552  	}
   553  	if stringContainsCTLByte(ruri) {
   554  		return errors.New("net/http: can't write control character in Request.URL")
   555  	}
   556  	// TODO: validate r.Method too? At least it's less likely to
   557  	// come from an attacker (more likely to be a constant in
   558  	// code).
   559  
   560  	// Wrap the writer in a bufio Writer if it's not already buffered.
   561  	// Don't always call NewWriter, as that forces a bytes.Buffer
   562  	// and other small bufio Writers to have a minimum 4k buffer
   563  	// size.
   564  	var bw *bufio.Writer
   565  	if _, ok := w.(io.ByteWriter); !ok {
   566  		bw = bufio.NewWriter(w)
   567  		w = bw
   568  	}
   569  
   570  	_, err = fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(r.Method, "GET"), ruri)
   571  	if err != nil {
   572  		return err
   573  	}
   574  
   575  	// Header lines
   576  	_, err = fmt.Fprintf(w, "Host: %s\r\n", host)
   577  	if err != nil {
   578  		return err
   579  	}
   580  	if trace != nil && trace.WroteHeaderField != nil {
   581  		trace.WroteHeaderField("Host", []string{host})
   582  	}
   583  
   584  	// Use the defaultUserAgent unless the Header contains one, which
   585  	// may be blank to not send the header.
   586  	userAgent := defaultUserAgent
   587  	if r.Header.has("User-Agent") {
   588  		userAgent = r.Header.Get("User-Agent")
   589  	}
   590  	if userAgent != "" {
   591  		_, err = fmt.Fprintf(w, "User-Agent: %s\r\n", userAgent)
   592  		if err != nil {
   593  			return err
   594  		}
   595  		if trace != nil && trace.WroteHeaderField != nil {
   596  			trace.WroteHeaderField("User-Agent", []string{userAgent})
   597  		}
   598  	}
   599  
   600  	// Process Body,ContentLength,Close,Trailer
   601  	tw, err := newTransferWriter(r)
   602  	if err != nil {
   603  		return err
   604  	}
   605  	err = tw.writeHeader(w, trace)
   606  	if err != nil {
   607  		return err
   608  	}
   609  
   610  	err = r.Header.writeSubset(w, reqWriteExcludeHeader, trace)
   611  	if err != nil {
   612  		return err
   613  	}
   614  
   615  	if extraHeaders != nil {
   616  		err = extraHeaders.write(w, trace)
   617  		if err != nil {
   618  			return err
   619  		}
   620  	}
   621  
   622  	_, err = io.WriteString(w, "\r\n")
   623  	if err != nil {
   624  		return err
   625  	}
   626  
   627  	if trace != nil && trace.WroteHeaders != nil {
   628  		trace.WroteHeaders()
   629  	}
   630  
   631  	// Flush and wait for 100-continue if expected.
   632  	if waitForContinue != nil {
   633  		if bw, ok := w.(*bufio.Writer); ok {
   634  			err = bw.Flush()
   635  			if err != nil {
   636  				return err
   637  			}
   638  		}
   639  		if trace != nil && trace.Wait100Continue != nil {
   640  			trace.Wait100Continue()
   641  		}
   642  		if !waitForContinue() {
   643  			r.closeBody()
   644  			return nil
   645  		}
   646  	}
   647  
   648  	if bw, ok := w.(*bufio.Writer); ok && tw.FlushHeaders {
   649  		if err := bw.Flush(); err != nil {
   650  			return err
   651  		}
   652  	}
   653  
   654  	// Write body and trailer
   655  	err = tw.writeBody(w)
   656  	if err != nil {
   657  		if tw.bodyReadError == err {
   658  			err = requestBodyReadError{err}
   659  		}
   660  		return err
   661  	}
   662  
   663  	if bw != nil {
   664  		return bw.Flush()
   665  	}
   666  	return nil
   667  }
   668  
   669  // requestBodyReadError wraps an error from (*Request).write to indicate
   670  // that the error came from a Read call on the Request.Body.
   671  // This error type should not escape the net/http package to users.
   672  type requestBodyReadError struct{ error }
   673  
   674  func idnaASCII(v string) (string, error) {
   675  	// TODO: Consider removing this check after verifying performance is okay.
   676  	// Right now punycode verification, length checks, context checks, and the
   677  	// permissible character tests are all omitted. It also prevents the ToASCII
   678  	// call from salvaging an invalid IDN, when possible. As a result it may be
   679  	// possible to have two IDNs that appear identical to the user where the
   680  	// ASCII-only version causes an error downstream whereas the non-ASCII
   681  	// version does not.
   682  	// Note that for correct ASCII IDNs ToASCII will only do considerably more
   683  	// work, but it will not cause an allocation.
   684  	if isASCII(v) {
   685  		return v, nil
   686  	}
   687  	return idna.Lookup.ToASCII(v)
   688  }
   689  
   690  // cleanHost cleans up the host sent in request's Host header.
   691  //
   692  // It both strips anything after '/' or ' ', and puts the value
   693  // into Punycode form, if necessary.
   694  //
   695  // Ideally we'd clean the Host header according to the spec:
   696  //   https://tools.ietf.org/html/rfc7230#section-5.4 (Host = uri-host [ ":" port ]")
   697  //   https://tools.ietf.org/html/rfc7230#section-2.7 (uri-host -> rfc3986's host)
   698  //   https://tools.ietf.org/html/rfc3986#section-3.2.2 (definition of host)
   699  // But practically, what we are trying to avoid is the situation in
   700  // issue 11206, where a malformed Host header used in the proxy context
   701  // would create a bad request. So it is enough to just truncate at the
   702  // first offending character.
   703  func cleanHost(in string) string {
   704  	if i := strings.IndexAny(in, " /"); i != -1 {
   705  		in = in[:i]
   706  	}
   707  	host, port, err := net.SplitHostPort(in)
   708  	if err != nil { // input was just a host
   709  		a, err := idnaASCII(in)
   710  		if err != nil {
   711  			return in // garbage in, garbage out
   712  		}
   713  		return a
   714  	}
   715  	a, err := idnaASCII(host)
   716  	if err != nil {
   717  		return in // garbage in, garbage out
   718  	}
   719  	return net.JoinHostPort(a, port)
   720  }
   721  
   722  // removeZone removes IPv6 zone identifier from host.
   723  // E.g., "[fe80::1%en0]:8080" to "[fe80::1]:8080"
   724  func removeZone(host string) string {
   725  	if !strings.HasPrefix(host, "[") {
   726  		return host
   727  	}
   728  	i := strings.LastIndex(host, "]")
   729  	if i < 0 {
   730  		return host
   731  	}
   732  	j := strings.LastIndex(host[:i], "%")
   733  	if j < 0 {
   734  		return host
   735  	}
   736  	return host[:j] + host[i:]
   737  }
   738  
   739  // ParseHTTPVersion parses a HTTP version string.
   740  // "HTTP/1.0" returns (1, 0, true).
   741  func ParseHTTPVersion(vers string) (major, minor int, ok bool) {
   742  	const Big = 1000000 // arbitrary upper bound
   743  	switch vers {
   744  	case "HTTP/1.1":
   745  		return 1, 1, true
   746  	case "HTTP/1.0":
   747  		return 1, 0, true
   748  	}
   749  	if !strings.HasPrefix(vers, "HTTP/") {
   750  		return 0, 0, false
   751  	}
   752  	dot := strings.Index(vers, ".")
   753  	if dot < 0 {
   754  		return 0, 0, false
   755  	}
   756  	major, err := strconv.Atoi(vers[5:dot])
   757  	if err != nil || major < 0 || major > Big {
   758  		return 0, 0, false
   759  	}
   760  	minor, err = strconv.Atoi(vers[dot+1:])
   761  	if err != nil || minor < 0 || minor > Big {
   762  		return 0, 0, false
   763  	}
   764  	return major, minor, true
   765  }
   766  
   767  func validMethod(method string) bool {
   768  	/*
   769  	     Method         = "OPTIONS"                ; Section 9.2
   770  	                    | "GET"                    ; Section 9.3
   771  	                    | "HEAD"                   ; Section 9.4
   772  	                    | "POST"                   ; Section 9.5
   773  	                    | "PUT"                    ; Section 9.6
   774  	                    | "DELETE"                 ; Section 9.7
   775  	                    | "TRACE"                  ; Section 9.8
   776  	                    | "CONNECT"                ; Section 9.9
   777  	                    | extension-method
   778  	   extension-method = token
   779  	     token          = 1*<any CHAR except CTLs or separators>
   780  	*/
   781  	return len(method) > 0 && strings.IndexFunc(method, isNotToken) == -1
   782  }
   783  
   784  // NewRequest returns a new Request given a method, URL, and optional body.
   785  //
   786  // If the provided body is also an io.Closer, the returned
   787  // Request.Body is set to body and will be closed by the Client
   788  // methods Do, Post, and PostForm, and Transport.RoundTrip.
   789  //
   790  // NewRequest returns a Request suitable for use with Client.Do or
   791  // Transport.RoundTrip. To create a request for use with testing a
   792  // Server Handler, either use the NewRequest function in the
   793  // net/http/httptest package, use ReadRequest, or manually update the
   794  // Request fields. See the Request type's documentation for the
   795  // difference between inbound and outbound request fields.
   796  //
   797  // If body is of type *bytes.Buffer, *bytes.Reader, or
   798  // *strings.Reader, the returned request's ContentLength is set to its
   799  // exact value (instead of -1), GetBody is populated (so 307 and 308
   800  // redirects can replay the body), and Body is set to NoBody if the
   801  // ContentLength is 0.
   802  func NewRequest(method, url string, body io.Reader) (*Request, error) {
   803  	if method == "" {
   804  		// We document that "" means "GET" for Request.Method, and people have
   805  		// relied on that from NewRequest, so keep that working.
   806  		// We still enforce validMethod for non-empty methods.
   807  		method = "GET"
   808  	}
   809  	if !validMethod(method) {
   810  		return nil, fmt.Errorf("net/http: invalid method %q", method)
   811  	}
   812  	u, err := parseURL(url) // Just url.Parse (url is shadowed for godoc).
   813  	if err != nil {
   814  		return nil, err
   815  	}
   816  	rc, ok := body.(io.ReadCloser)
   817  	if !ok && body != nil {
   818  		rc = ioutil.NopCloser(body)
   819  	}
   820  	// The host's colon:port should be normalized. See Issue 14836.
   821  	u.Host = removeEmptyPort(u.Host)
   822  	req := &Request{
   823  		Method:     method,
   824  		URL:        u,
   825  		Proto:      "HTTP/1.1",
   826  		ProtoMajor: 1,
   827  		ProtoMinor: 1,
   828  		Header:     make(Header),
   829  		Body:       rc,
   830  		Host:       u.Host,
   831  	}
   832  	if body != nil {
   833  		switch v := body.(type) {
   834  		case *bytes.Buffer:
   835  			req.ContentLength = int64(v.Len())
   836  			buf := v.Bytes()
   837  			req.GetBody = func() (io.ReadCloser, error) {
   838  				r := bytes.NewReader(buf)
   839  				return ioutil.NopCloser(r), nil
   840  			}
   841  		case *bytes.Reader:
   842  			req.ContentLength = int64(v.Len())
   843  			snapshot := *v
   844  			req.GetBody = func() (io.ReadCloser, error) {
   845  				r := snapshot
   846  				return ioutil.NopCloser(&r), nil
   847  			}
   848  		case *strings.Reader:
   849  			req.ContentLength = int64(v.Len())
   850  			snapshot := *v
   851  			req.GetBody = func() (io.ReadCloser, error) {
   852  				r := snapshot
   853  				return ioutil.NopCloser(&r), nil
   854  			}
   855  		default:
   856  			// This is where we'd set it to -1 (at least
   857  			// if body != NoBody) to mean unknown, but
   858  			// that broke people during the Go 1.8 testing
   859  			// period. People depend on it being 0 I
   860  			// guess. Maybe retry later. See Issue 18117.
   861  		}
   862  		// For client requests, Request.ContentLength of 0
   863  		// means either actually 0, or unknown. The only way
   864  		// to explicitly say that the ContentLength is zero is
   865  		// to set the Body to nil. But turns out too much code
   866  		// depends on NewRequest returning a non-nil Body,
   867  		// so we use a well-known ReadCloser variable instead
   868  		// and have the http package also treat that sentinel
   869  		// variable to mean explicitly zero.
   870  		if req.GetBody != nil && req.ContentLength == 0 {
   871  			req.Body = NoBody
   872  			req.GetBody = func() (io.ReadCloser, error) { return NoBody, nil }
   873  		}
   874  	}
   875  
   876  	return req, nil
   877  }
   878  
   879  // BasicAuth returns the username and password provided in the request's
   880  // Authorization header, if the request uses HTTP Basic Authentication.
   881  // See RFC 2617, Section 2.
   882  func (r *Request) BasicAuth() (username, password string, ok bool) {
   883  	auth := r.Header.Get("Authorization")
   884  	if auth == "" {
   885  		return
   886  	}
   887  	return parseBasicAuth(auth)
   888  }
   889  
   890  // parseBasicAuth parses an HTTP Basic Authentication string.
   891  // "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==" returns ("Aladdin", "open sesame", true).
   892  func parseBasicAuth(auth string) (username, password string, ok bool) {
   893  	const prefix = "Basic "
   894  	// Case insensitive prefix match. See Issue 22736.
   895  	if len(auth) < len(prefix) || !strings.EqualFold(auth[:len(prefix)], prefix) {
   896  		return
   897  	}
   898  	c, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
   899  	if err != nil {
   900  		return
   901  	}
   902  	cs := string(c)
   903  	s := strings.IndexByte(cs, ':')
   904  	if s < 0 {
   905  		return
   906  	}
   907  	return cs[:s], cs[s+1:], true
   908  }
   909  
   910  // SetBasicAuth sets the request's Authorization header to use HTTP
   911  // Basic Authentication with the provided username and password.
   912  //
   913  // With HTTP Basic Authentication the provided username and password
   914  // are not encrypted.
   915  func (r *Request) SetBasicAuth(username, password string) {
   916  	r.Header.Set("Authorization", "Basic "+basicAuth(username, password))
   917  }
   918  
   919  // parseRequestLine parses "GET /foo HTTP/1.1" into its three parts.
   920  func parseRequestLine(line string) (method, requestURI, proto string, ok bool) {
   921  	s1 := strings.Index(line, " ")
   922  	s2 := strings.Index(line[s1+1:], " ")
   923  	if s1 < 0 || s2 < 0 {
   924  		return
   925  	}
   926  	s2 += s1 + 1
   927  	return line[:s1], line[s1+1 : s2], line[s2+1:], true
   928  }
   929  
   930  var textprotoReaderPool sync.Pool
   931  
   932  func newTextprotoReader(br *bufio.Reader) *textproto.Reader {
   933  	if v := textprotoReaderPool.Get(); v != nil {
   934  		tr := v.(*textproto.Reader)
   935  		tr.R = br
   936  		return tr
   937  	}
   938  	return textproto.NewReader(br)
   939  }
   940  
   941  func putTextprotoReader(r *textproto.Reader) {
   942  	r.R = nil
   943  	textprotoReaderPool.Put(r)
   944  }
   945  
   946  // ReadRequest reads and parses an incoming request from b.
   947  //
   948  // ReadRequest is a low-level function and should only be used for
   949  // specialized applications; most code should use the Server to read
   950  // requests and handle them via the Handler interface. ReadRequest
   951  // only supports HTTP/1.x requests. For HTTP/2, use golang.org/x/net/http2.
   952  func ReadRequest(b *bufio.Reader) (*Request, error) {
   953  	return readRequest(b, deleteHostHeader)
   954  }
   955  
   956  // Constants for readRequest's deleteHostHeader parameter.
   957  const (
   958  	deleteHostHeader = true
   959  	keepHostHeader   = false
   960  )
   961  
   962  func readRequest(b *bufio.Reader, deleteHostHeader bool) (req *Request, err error) {
   963  	tp := newTextprotoReader(b)
   964  	req = new(Request)
   965  
   966  	// First line: GET /index.html HTTP/1.0
   967  	var s string
   968  	if s, err = tp.ReadLine(); err != nil {
   969  		return nil, err
   970  	}
   971  	defer func() {
   972  		putTextprotoReader(tp)
   973  		if err == io.EOF {
   974  			err = io.ErrUnexpectedEOF
   975  		}
   976  	}()
   977  
   978  	var ok bool
   979  	req.Method, req.RequestURI, req.Proto, ok = parseRequestLine(s)
   980  	if !ok {
   981  		return nil, &badStringError{"malformed HTTP request", s}
   982  	}
   983  	if !validMethod(req.Method) {
   984  		return nil, &badStringError{"invalid method", req.Method}
   985  	}
   986  	rawurl := req.RequestURI
   987  	if req.ProtoMajor, req.ProtoMinor, ok = ParseHTTPVersion(req.Proto); !ok {
   988  		return nil, &badStringError{"malformed HTTP version", req.Proto}
   989  	}
   990  
   991  	// CONNECT requests are used two different ways, and neither uses a full URL:
   992  	// The standard use is to tunnel HTTPS through an HTTP proxy.
   993  	// It looks like "CONNECT www.google.com:443 HTTP/1.1", and the parameter is
   994  	// just the authority section of a URL. This information should go in req.URL.Host.
   995  	//
   996  	// The net/rpc package also uses CONNECT, but there the parameter is a path
   997  	// that starts with a slash. It can be parsed with the regular URL parser,
   998  	// and the path will end up in req.URL.Path, where it needs to be in order for
   999  	// RPC to work.
  1000  	justAuthority := req.Method == "CONNECT" && !strings.HasPrefix(rawurl, "/")
  1001  	if justAuthority {
  1002  		rawurl = "http://" + rawurl
  1003  	}
  1004  
  1005  	if req.URL, err = url.ParseRequestURI(rawurl); err != nil {
  1006  		return nil, err
  1007  	}
  1008  
  1009  	if justAuthority {
  1010  		// Strip the bogus "http://" back off.
  1011  		req.URL.Scheme = ""
  1012  	}
  1013  
  1014  	// Subsequent lines: Key: value.
  1015  	mimeHeader, err := tp.ReadMIMEHeader()
  1016  	if err != nil {
  1017  		return nil, err
  1018  	}
  1019  	req.Header = Header(mimeHeader)
  1020  
  1021  	// RFC 7230, section 5.3: Must treat
  1022  	//	GET /index.html HTTP/1.1
  1023  	//	Host: www.google.com
  1024  	// and
  1025  	//	GET http://www.google.com/index.html HTTP/1.1
  1026  	//	Host: doesntmatter
  1027  	// the same. In the second case, any Host line is ignored.
  1028  	req.Host = req.URL.Host
  1029  	if req.Host == "" {
  1030  		req.Host = req.Header.get("Host")
  1031  	}
  1032  	if deleteHostHeader {
  1033  		delete(req.Header, "Host")
  1034  	}
  1035  
  1036  	fixPragmaCacheControl(req.Header)
  1037  
  1038  	req.Close = shouldClose(req.ProtoMajor, req.ProtoMinor, req.Header, false)
  1039  
  1040  	err = readTransfer(req, b)
  1041  	if err != nil {
  1042  		return nil, err
  1043  	}
  1044  
  1045  	if req.isH2Upgrade() {
  1046  		// Because it's neither chunked, nor declared:
  1047  		req.ContentLength = -1
  1048  
  1049  		// We want to give handlers a chance to hijack the
  1050  		// connection, but we need to prevent the Server from
  1051  		// dealing with the connection further if it's not
  1052  		// hijacked. Set Close to ensure that:
  1053  		req.Close = true
  1054  	}
  1055  	return req, nil
  1056  }
  1057  
  1058  // MaxBytesReader is similar to io.LimitReader but is intended for
  1059  // limiting the size of incoming request bodies. In contrast to
  1060  // io.LimitReader, MaxBytesReader's result is a ReadCloser, returns a
  1061  // non-EOF error for a Read beyond the limit, and closes the
  1062  // underlying reader when its Close method is called.
  1063  //
  1064  // MaxBytesReader prevents clients from accidentally or maliciously
  1065  // sending a large request and wasting server resources.
  1066  func MaxBytesReader(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser {
  1067  	return &maxBytesReader{w: w, r: r, n: n}
  1068  }
  1069  
  1070  type maxBytesReader struct {
  1071  	w   ResponseWriter
  1072  	r   io.ReadCloser // underlying reader
  1073  	n   int64         // max bytes remaining
  1074  	err error         // sticky error
  1075  }
  1076  
  1077  func (l *maxBytesReader) Read(p []byte) (n int, err error) {
  1078  	if l.err != nil {
  1079  		return 0, l.err
  1080  	}
  1081  	if len(p) == 0 {
  1082  		return 0, nil
  1083  	}
  1084  	// If they asked for a 32KB byte read but only 5 bytes are
  1085  	// remaining, no need to read 32KB. 6 bytes will answer the
  1086  	// question of the whether we hit the limit or go past it.
  1087  	if int64(len(p)) > l.n+1 {
  1088  		p = p[:l.n+1]
  1089  	}
  1090  	n, err = l.r.Read(p)
  1091  
  1092  	if int64(n) <= l.n {
  1093  		l.n -= int64(n)
  1094  		l.err = err
  1095  		return n, err
  1096  	}
  1097  
  1098  	n = int(l.n)
  1099  	l.n = 0
  1100  
  1101  	// The server code and client code both use
  1102  	// maxBytesReader. This "requestTooLarge" check is
  1103  	// only used by the server code. To prevent binaries
  1104  	// which only using the HTTP Client code (such as
  1105  	// cmd/go) from also linking in the HTTP server, don't
  1106  	// use a static type assertion to the server
  1107  	// "*response" type. Check this interface instead:
  1108  	type requestTooLarger interface {
  1109  		requestTooLarge()
  1110  	}
  1111  	if res, ok := l.w.(requestTooLarger); ok {
  1112  		res.requestTooLarge()
  1113  	}
  1114  	l.err = errors.New("http: request body too large")
  1115  	return n, l.err
  1116  }
  1117  
  1118  func (l *maxBytesReader) Close() error {
  1119  	return l.r.Close()
  1120  }
  1121  
  1122  func copyValues(dst, src url.Values) {
  1123  	for k, vs := range src {
  1124  		for _, value := range vs {
  1125  			dst.Add(k, value)
  1126  		}
  1127  	}
  1128  }
  1129  
  1130  func parsePostForm(r *Request) (vs url.Values, err error) {
  1131  	if r.Body == nil {
  1132  		err = errors.New("missing form body")
  1133  		return
  1134  	}
  1135  	ct := r.Header.Get("Content-Type")
  1136  	// RFC 7231, section 3.1.1.5 - empty type
  1137  	//   MAY be treated as application/octet-stream
  1138  	if ct == "" {
  1139  		ct = "application/octet-stream"
  1140  	}
  1141  	ct, _, err = mime.ParseMediaType(ct)
  1142  	switch {
  1143  	case ct == "application/x-www-form-urlencoded":
  1144  		var reader io.Reader = r.Body
  1145  		maxFormSize := int64(1<<63 - 1)
  1146  		if _, ok := r.Body.(*maxBytesReader); !ok {
  1147  			maxFormSize = int64(10 << 20) // 10 MB is a lot of text.
  1148  			reader = io.LimitReader(r.Body, maxFormSize+1)
  1149  		}
  1150  		b, e := ioutil.ReadAll(reader)
  1151  		if e != nil {
  1152  			if err == nil {
  1153  				err = e
  1154  			}
  1155  			break
  1156  		}
  1157  		if int64(len(b)) > maxFormSize {
  1158  			err = errors.New("http: POST too large")
  1159  			return
  1160  		}
  1161  		vs, e = url.ParseQuery(string(b))
  1162  		if err == nil {
  1163  			err = e
  1164  		}
  1165  	case ct == "multipart/form-data":
  1166  		// handled by ParseMultipartForm (which is calling us, or should be)
  1167  		// TODO(bradfitz): there are too many possible
  1168  		// orders to call too many functions here.
  1169  		// Clean this up and write more tests.
  1170  		// request_test.go contains the start of this,
  1171  		// in TestParseMultipartFormOrder and others.
  1172  	}
  1173  	return
  1174  }
  1175  
  1176  // ParseForm populates r.Form and r.PostForm.
  1177  //
  1178  // For all requests, ParseForm parses the raw query from the URL and updates
  1179  // r.Form.
  1180  //
  1181  // For POST, PUT, and PATCH requests, it also parses the request body as a form
  1182  // and puts the results into both r.PostForm and r.Form. Request body parameters
  1183  // take precedence over URL query string values in r.Form.
  1184  //
  1185  // For other HTTP methods, or when the Content-Type is not
  1186  // application/x-www-form-urlencoded, the request Body is not read, and
  1187  // r.PostForm is initialized to a non-nil, empty value.
  1188  //
  1189  // If the request Body's size has not already been limited by MaxBytesReader,
  1190  // the size is capped at 10MB.
  1191  //
  1192  // ParseMultipartForm calls ParseForm automatically.
  1193  // ParseForm is idempotent.
  1194  func (r *Request) ParseForm() error {
  1195  	var err error
  1196  	if r.PostForm == nil {
  1197  		if r.Method == "POST" || r.Method == "PUT" || r.Method == "PATCH" {
  1198  			r.PostForm, err = parsePostForm(r)
  1199  		}
  1200  		if r.PostForm == nil {
  1201  			r.PostForm = make(url.Values)
  1202  		}
  1203  	}
  1204  	if r.Form == nil {
  1205  		if len(r.PostForm) > 0 {
  1206  			r.Form = make(url.Values)
  1207  			copyValues(r.Form, r.PostForm)
  1208  		}
  1209  		var newValues url.Values
  1210  		if r.URL != nil {
  1211  			var e error
  1212  			newValues, e = url.ParseQuery(r.URL.RawQuery)
  1213  			if err == nil {
  1214  				err = e
  1215  			}
  1216  		}
  1217  		if newValues == nil {
  1218  			newValues = make(url.Values)
  1219  		}
  1220  		if r.Form == nil {
  1221  			r.Form = newValues
  1222  		} else {
  1223  			copyValues(r.Form, newValues)
  1224  		}
  1225  	}
  1226  	return err
  1227  }
  1228  
  1229  // ParseMultipartForm parses a request body as multipart/form-data.
  1230  // The whole request body is parsed and up to a total of maxMemory bytes of
  1231  // its file parts are stored in memory, with the remainder stored on
  1232  // disk in temporary files.
  1233  // ParseMultipartForm calls ParseForm if necessary.
  1234  // After one call to ParseMultipartForm, subsequent calls have no effect.
  1235  func (r *Request) ParseMultipartForm(maxMemory int64) error {
  1236  	if r.MultipartForm == multipartByReader {
  1237  		return errors.New("http: multipart handled by MultipartReader")
  1238  	}
  1239  	if r.Form == nil {
  1240  		err := r.ParseForm()
  1241  		if err != nil {
  1242  			return err
  1243  		}
  1244  	}
  1245  	if r.MultipartForm != nil {
  1246  		return nil
  1247  	}
  1248  
  1249  	mr, err := r.multipartReader(false)
  1250  	if err != nil {
  1251  		return err
  1252  	}
  1253  
  1254  	f, err := mr.ReadForm(maxMemory)
  1255  	if err != nil {
  1256  		return err
  1257  	}
  1258  
  1259  	if r.PostForm == nil {
  1260  		r.PostForm = make(url.Values)
  1261  	}
  1262  	for k, v := range f.Value {
  1263  		r.Form[k] = append(r.Form[k], v...)
  1264  		// r.PostForm should also be populated. See Issue 9305.
  1265  		r.PostForm[k] = append(r.PostForm[k], v...)
  1266  	}
  1267  
  1268  	r.MultipartForm = f
  1269  
  1270  	return nil
  1271  }
  1272  
  1273  // FormValue returns the first value for the named component of the query.
  1274  // POST and PUT body parameters take precedence over URL query string values.
  1275  // FormValue calls ParseMultipartForm and ParseForm if necessary and ignores
  1276  // any errors returned by these functions.
  1277  // If key is not present, FormValue returns the empty string.
  1278  // To access multiple values of the same key, call ParseForm and
  1279  // then inspect Request.Form directly.
  1280  func (r *Request) FormValue(key string) string {
  1281  	if r.Form == nil {
  1282  		r.ParseMultipartForm(defaultMaxMemory)
  1283  	}
  1284  	if vs := r.Form[key]; len(vs) > 0 {
  1285  		return vs[0]
  1286  	}
  1287  	return ""
  1288  }
  1289  
  1290  // PostFormValue returns the first value for the named component of the POST,
  1291  // PATCH, or PUT request body. URL query parameters are ignored.
  1292  // PostFormValue calls ParseMultipartForm and ParseForm if necessary and ignores
  1293  // any errors returned by these functions.
  1294  // If key is not present, PostFormValue returns the empty string.
  1295  func (r *Request) PostFormValue(key string) string {
  1296  	if r.PostForm == nil {
  1297  		r.ParseMultipartForm(defaultMaxMemory)
  1298  	}
  1299  	if vs := r.PostForm[key]; len(vs) > 0 {
  1300  		return vs[0]
  1301  	}
  1302  	return ""
  1303  }
  1304  
  1305  // FormFile returns the first file for the provided form key.
  1306  // FormFile calls ParseMultipartForm and ParseForm if necessary.
  1307  func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, error) {
  1308  	if r.MultipartForm == multipartByReader {
  1309  		return nil, nil, errors.New("http: multipart handled by MultipartReader")
  1310  	}
  1311  	if r.MultipartForm == nil {
  1312  		err := r.ParseMultipartForm(defaultMaxMemory)
  1313  		if err != nil {
  1314  			return nil, nil, err
  1315  		}
  1316  	}
  1317  	if r.MultipartForm != nil && r.MultipartForm.File != nil {
  1318  		if fhs := r.MultipartForm.File[key]; len(fhs) > 0 {
  1319  			f, err := fhs[0].Open()
  1320  			return f, fhs[0], err
  1321  		}
  1322  	}
  1323  	return nil, nil, ErrMissingFile
  1324  }
  1325  
  1326  func (r *Request) expectsContinue() bool {
  1327  	return hasToken(r.Header.get("Expect"), "100-continue")
  1328  }
  1329  
  1330  func (r *Request) wantsHttp10KeepAlive() bool {
  1331  	if r.ProtoMajor != 1 || r.ProtoMinor != 0 {
  1332  		return false
  1333  	}
  1334  	return hasToken(r.Header.get("Connection"), "keep-alive")
  1335  }
  1336  
  1337  func (r *Request) wantsClose() bool {
  1338  	if r.Close {
  1339  		return true
  1340  	}
  1341  	return hasToken(r.Header.get("Connection"), "close")
  1342  }
  1343  
  1344  func (r *Request) closeBody() {
  1345  	if r.Body != nil {
  1346  		r.Body.Close()
  1347  	}
  1348  }
  1349  
  1350  func (r *Request) isReplayable() bool {
  1351  	if r.Body == nil || r.Body == NoBody || r.GetBody != nil {
  1352  		switch valueOrDefault(r.Method, "GET") {
  1353  		case "GET", "HEAD", "OPTIONS", "TRACE":
  1354  			return true
  1355  		}
  1356  		// The Idempotency-Key, while non-standard, is widely used to
  1357  		// mean a POST or other request is idempotent. See
  1358  		// https://golang.org/issue/19943#issuecomment-421092421
  1359  		if r.Header.has("Idempotency-Key") || r.Header.has("X-Idempotency-Key") {
  1360  			return true
  1361  		}
  1362  	}
  1363  	return false
  1364  }
  1365  
  1366  // outgoingLength reports the Content-Length of this outgoing (Client) request.
  1367  // It maps 0 into -1 (unknown) when the Body is non-nil.
  1368  func (r *Request) outgoingLength() int64 {
  1369  	if r.Body == nil || r.Body == NoBody {
  1370  		return 0
  1371  	}
  1372  	if r.ContentLength != 0 {
  1373  		return r.ContentLength
  1374  	}
  1375  	return -1
  1376  }
  1377  
  1378  // requestMethodUsuallyLacksBody reports whether the given request
  1379  // method is one that typically does not involve a request body.
  1380  // This is used by the Transport (via
  1381  // transferWriter.shouldSendChunkedRequestBody) to determine whether
  1382  // we try to test-read a byte from a non-nil Request.Body when
  1383  // Request.outgoingLength() returns -1. See the comments in
  1384  // shouldSendChunkedRequestBody.
  1385  func requestMethodUsuallyLacksBody(method string) bool {
  1386  	switch method {
  1387  	case "GET", "HEAD", "DELETE", "OPTIONS", "PROPFIND", "SEARCH":
  1388  		return true
  1389  	}
  1390  	return false
  1391  }
  1392  
  1393  // requiresHTTP1 reports whether this request requires being sent on
  1394  // an HTTP/1 connection.
  1395  func (r *Request) requiresHTTP1() bool {
  1396  	return hasToken(r.Header.Get("Connection"), "upgrade") &&
  1397  		strings.EqualFold(r.Header.Get("Upgrade"), "websocket")
  1398  }
  1399  

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