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  	"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  	// 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 PATCH, 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 PATCH, POST
   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: Set the Request's context with NewRequestWithContext
   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 cancellation.
   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  //
   349  // To create a new request with a context, use NewRequestWithContext.
   350  // To change the context of a request (such as an incoming) you then
   351  // also want to modify to send back out, use Request.Clone. Between
   352  // those two uses, it's rare to need WithContext.
   353  func (r *Request) WithContext(ctx context.Context) *Request {
   354  	if ctx == nil {
   355  		panic("nil context")
   356  	}
   357  	r2 := new(Request)
   358  	*r2 = *r
   359  	r2.ctx = ctx
   360  	r2.URL = cloneURL(r.URL) // legacy behavior; TODO: try to remove. Issue 23544
   361  	return r2
   362  }
   363  
   364  // Clone returns a deep copy of r with its context changed to ctx.
   365  // The provided ctx must be non-nil.
   366  //
   367  // For an outgoing client request, the context controls the entire
   368  // lifetime of a request and its response: obtaining a connection,
   369  // sending the request, and reading the response headers and body.
   370  func (r *Request) Clone(ctx context.Context) *Request {
   371  	if ctx == nil {
   372  		panic("nil context")
   373  	}
   374  	r2 := new(Request)
   375  	*r2 = *r
   376  	r2.ctx = ctx
   377  	r2.URL = cloneURL(r.URL)
   378  	if r.Header != nil {
   379  		r2.Header = r.Header.Clone()
   380  	}
   381  	if r.Trailer != nil {
   382  		r2.Trailer = r.Trailer.Clone()
   383  	}
   384  	if s := r.TransferEncoding; s != nil {
   385  		s2 := make([]string, len(s))
   386  		copy(s2, s)
   387  		r2.TransferEncoding = s
   388  	}
   389  	r2.Form = cloneURLValues(r.Form)
   390  	r2.PostForm = cloneURLValues(r.PostForm)
   391  	r2.MultipartForm = cloneMultipartForm(r.MultipartForm)
   392  	return r2
   393  }
   394  
   395  // ProtoAtLeast reports whether the HTTP protocol used
   396  // in the request is at least major.minor.
   397  func (r *Request) ProtoAtLeast(major, minor int) bool {
   398  	return r.ProtoMajor > major ||
   399  		r.ProtoMajor == major && r.ProtoMinor >= minor
   400  }
   401  
   402  // UserAgent returns the client's User-Agent, if sent in the request.
   403  func (r *Request) UserAgent() string {
   404  	return r.Header.Get("User-Agent")
   405  }
   406  
   407  // Cookies parses and returns the HTTP cookies sent with the request.
   408  func (r *Request) Cookies() []*Cookie {
   409  	return readCookies(r.Header, "")
   410  }
   411  
   412  // ErrNoCookie is returned by Request's Cookie method when a cookie is not found.
   413  var ErrNoCookie = errors.New("http: named cookie not present")
   414  
   415  // Cookie returns the named cookie provided in the request or
   416  // ErrNoCookie if not found.
   417  // If multiple cookies match the given name, only one cookie will
   418  // be returned.
   419  func (r *Request) Cookie(name string) (*Cookie, error) {
   420  	for _, c := range readCookies(r.Header, name) {
   421  		return c, nil
   422  	}
   423  	return nil, ErrNoCookie
   424  }
   425  
   426  // AddCookie adds a cookie to the request. Per RFC 6265 section 5.4,
   427  // AddCookie does not attach more than one Cookie header field. That
   428  // means all cookies, if any, are written into the same line,
   429  // separated by semicolon.
   430  func (r *Request) AddCookie(c *Cookie) {
   431  	s := fmt.Sprintf("%s=%s", sanitizeCookieName(c.Name), sanitizeCookieValue(c.Value))
   432  	if c := r.Header.Get("Cookie"); c != "" {
   433  		r.Header.Set("Cookie", c+"; "+s)
   434  	} else {
   435  		r.Header.Set("Cookie", s)
   436  	}
   437  }
   438  
   439  // Referer returns the referring URL, if sent in the request.
   440  //
   441  // Referer is misspelled as in the request itself, a mistake from the
   442  // earliest days of HTTP.  This value can also be fetched from the
   443  // Header map as Header["Referer"]; the benefit of making it available
   444  // as a method is that the compiler can diagnose programs that use the
   445  // alternate (correct English) spelling req.Referrer() but cannot
   446  // diagnose programs that use Header["Referrer"].
   447  func (r *Request) Referer() string {
   448  	return r.Header.Get("Referer")
   449  }
   450  
   451  // multipartByReader is a sentinel value.
   452  // Its presence in Request.MultipartForm indicates that parsing of the request
   453  // body has been handed off to a MultipartReader instead of ParseMultipartForm.
   454  var multipartByReader = &multipart.Form{
   455  	Value: make(map[string][]string),
   456  	File:  make(map[string][]*multipart.FileHeader),
   457  }
   458  
   459  // MultipartReader returns a MIME multipart reader if this is a
   460  // multipart/form-data or a multipart/mixed POST request, else returns nil and an error.
   461  // Use this function instead of ParseMultipartForm to
   462  // process the request body as a stream.
   463  func (r *Request) MultipartReader() (*multipart.Reader, error) {
   464  	if r.MultipartForm == multipartByReader {
   465  		return nil, errors.New("http: MultipartReader called twice")
   466  	}
   467  	if r.MultipartForm != nil {
   468  		return nil, errors.New("http: multipart handled by ParseMultipartForm")
   469  	}
   470  	r.MultipartForm = multipartByReader
   471  	return r.multipartReader(true)
   472  }
   473  
   474  func (r *Request) multipartReader(allowMixed bool) (*multipart.Reader, error) {
   475  	v := r.Header.Get("Content-Type")
   476  	if v == "" {
   477  		return nil, ErrNotMultipart
   478  	}
   479  	d, params, err := mime.ParseMediaType(v)
   480  	if err != nil || !(d == "multipart/form-data" || allowMixed && d == "multipart/mixed") {
   481  		return nil, ErrNotMultipart
   482  	}
   483  	boundary, ok := params["boundary"]
   484  	if !ok {
   485  		return nil, ErrMissingBoundary
   486  	}
   487  	return multipart.NewReader(r.Body, boundary), nil
   488  }
   489  
   490  // isH2Upgrade reports whether r represents the http2 "client preface"
   491  // magic string.
   492  func (r *Request) isH2Upgrade() bool {
   493  	return r.Method == "PRI" && len(r.Header) == 0 && r.URL.Path == "*" && r.Proto == "HTTP/2.0"
   494  }
   495  
   496  // Return value if nonempty, def otherwise.
   497  func valueOrDefault(value, def string) string {
   498  	if value != "" {
   499  		return value
   500  	}
   501  	return def
   502  }
   503  
   504  // NOTE: This is not intended to reflect the actual Go version being used.
   505  // It was changed at the time of Go 1.1 release because the former User-Agent
   506  // had ended up on a blacklist for some intrusion detection systems.
   507  // See https://codereview.appspot.com/7532043.
   508  const defaultUserAgent = "Go-http-client/1.1"
   509  
   510  // Write writes an HTTP/1.1 request, which is the header and body, in wire format.
   511  // This method consults the following fields of the request:
   512  //	Host
   513  //	URL
   514  //	Method (defaults to "GET")
   515  //	Header
   516  //	ContentLength
   517  //	TransferEncoding
   518  //	Body
   519  //
   520  // If Body is present, Content-Length is <= 0 and TransferEncoding
   521  // hasn't been set to "identity", Write adds "Transfer-Encoding:
   522  // chunked" to the header. Body is closed after it is sent.
   523  func (r *Request) Write(w io.Writer) error {
   524  	return r.write(w, false, nil, nil)
   525  }
   526  
   527  // WriteProxy is like Write but writes the request in the form
   528  // expected by an HTTP proxy. In particular, WriteProxy writes the
   529  // initial Request-URI line of the request with an absolute URI, per
   530  // section 5.3 of RFC 7230, including the scheme and host.
   531  // In either case, WriteProxy also writes a Host header, using
   532  // either r.Host or r.URL.Host.
   533  func (r *Request) WriteProxy(w io.Writer) error {
   534  	return r.write(w, true, nil, nil)
   535  }
   536  
   537  // errMissingHost is returned by Write when there is no Host or URL present in
   538  // the Request.
   539  var errMissingHost = errors.New("http: Request.Write on Request with no Host or URL set")
   540  
   541  // extraHeaders may be nil
   542  // waitForContinue may be nil
   543  func (r *Request) write(w io.Writer, usingProxy bool, extraHeaders Header, waitForContinue func() bool) (err error) {
   544  	trace := httptrace.ContextClientTrace(r.Context())
   545  	if trace != nil && trace.WroteRequest != nil {
   546  		defer func() {
   547  			trace.WroteRequest(httptrace.WroteRequestInfo{
   548  				Err: err,
   549  			})
   550  		}()
   551  	}
   552  
   553  	// Find the target host. Prefer the Host: header, but if that
   554  	// is not given, use the host from the request URL.
   555  	//
   556  	// Clean the host, in case it arrives with unexpected stuff in it.
   557  	host := cleanHost(r.Host)
   558  	if host == "" {
   559  		if r.URL == nil {
   560  			return errMissingHost
   561  		}
   562  		host = cleanHost(r.URL.Host)
   563  	}
   564  
   565  	// According to RFC 6874, an HTTP client, proxy, or other
   566  	// intermediary must remove any IPv6 zone identifier attached
   567  	// to an outgoing URI.
   568  	host = removeZone(host)
   569  
   570  	ruri := r.URL.RequestURI()
   571  	if usingProxy && r.URL.Scheme != "" && r.URL.Opaque == "" {
   572  		ruri = r.URL.Scheme + "://" + host + ruri
   573  	} else if r.Method == "CONNECT" && r.URL.Path == "" {
   574  		// CONNECT requests normally give just the host and port, not a full URL.
   575  		ruri = host
   576  		if r.URL.Opaque != "" {
   577  			ruri = r.URL.Opaque
   578  		}
   579  	}
   580  	if stringContainsCTLByte(ruri) {
   581  		return errors.New("net/http: can't write control character in Request.URL")
   582  	}
   583  	// TODO: validate r.Method too? At least it's less likely to
   584  	// come from an attacker (more likely to be a constant in
   585  	// code).
   586  
   587  	// Wrap the writer in a bufio Writer if it's not already buffered.
   588  	// Don't always call NewWriter, as that forces a bytes.Buffer
   589  	// and other small bufio Writers to have a minimum 4k buffer
   590  	// size.
   591  	var bw *bufio.Writer
   592  	if _, ok := w.(io.ByteWriter); !ok {
   593  		bw = bufio.NewWriter(w)
   594  		w = bw
   595  	}
   596  
   597  	_, err = fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(r.Method, "GET"), ruri)
   598  	if err != nil {
   599  		return err
   600  	}
   601  
   602  	// Header lines
   603  	_, err = fmt.Fprintf(w, "Host: %s\r\n", host)
   604  	if err != nil {
   605  		return err
   606  	}
   607  	if trace != nil && trace.WroteHeaderField != nil {
   608  		trace.WroteHeaderField("Host", []string{host})
   609  	}
   610  
   611  	// Use the defaultUserAgent unless the Header contains one, which
   612  	// may be blank to not send the header.
   613  	userAgent := defaultUserAgent
   614  	if r.Header.has("User-Agent") {
   615  		userAgent = r.Header.Get("User-Agent")
   616  	}
   617  	if userAgent != "" {
   618  		_, err = fmt.Fprintf(w, "User-Agent: %s\r\n", userAgent)
   619  		if err != nil {
   620  			return err
   621  		}
   622  		if trace != nil && trace.WroteHeaderField != nil {
   623  			trace.WroteHeaderField("User-Agent", []string{userAgent})
   624  		}
   625  	}
   626  
   627  	// Process Body,ContentLength,Close,Trailer
   628  	tw, err := newTransferWriter(r)
   629  	if err != nil {
   630  		return err
   631  	}
   632  	err = tw.writeHeader(w, trace)
   633  	if err != nil {
   634  		return err
   635  	}
   636  
   637  	err = r.Header.writeSubset(w, reqWriteExcludeHeader, trace)
   638  	if err != nil {
   639  		return err
   640  	}
   641  
   642  	if extraHeaders != nil {
   643  		err = extraHeaders.write(w, trace)
   644  		if err != nil {
   645  			return err
   646  		}
   647  	}
   648  
   649  	_, err = io.WriteString(w, "\r\n")
   650  	if err != nil {
   651  		return err
   652  	}
   653  
   654  	if trace != nil && trace.WroteHeaders != nil {
   655  		trace.WroteHeaders()
   656  	}
   657  
   658  	// Flush and wait for 100-continue if expected.
   659  	if waitForContinue != nil {
   660  		if bw, ok := w.(*bufio.Writer); ok {
   661  			err = bw.Flush()
   662  			if err != nil {
   663  				return err
   664  			}
   665  		}
   666  		if trace != nil && trace.Wait100Continue != nil {
   667  			trace.Wait100Continue()
   668  		}
   669  		if !waitForContinue() {
   670  			r.closeBody()
   671  			return nil
   672  		}
   673  	}
   674  
   675  	if bw, ok := w.(*bufio.Writer); ok && tw.FlushHeaders {
   676  		if err := bw.Flush(); err != nil {
   677  			return err
   678  		}
   679  	}
   680  
   681  	// Write body and trailer
   682  	err = tw.writeBody(w)
   683  	if err != nil {
   684  		if tw.bodyReadError == err {
   685  			err = requestBodyReadError{err}
   686  		}
   687  		return err
   688  	}
   689  
   690  	if bw != nil {
   691  		return bw.Flush()
   692  	}
   693  	return nil
   694  }
   695  
   696  // requestBodyReadError wraps an error from (*Request).write to indicate
   697  // that the error came from a Read call on the Request.Body.
   698  // This error type should not escape the net/http package to users.
   699  type requestBodyReadError struct{ error }
   700  
   701  func idnaASCII(v string) (string, error) {
   702  	// TODO: Consider removing this check after verifying performance is okay.
   703  	// Right now punycode verification, length checks, context checks, and the
   704  	// permissible character tests are all omitted. It also prevents the ToASCII
   705  	// call from salvaging an invalid IDN, when possible. As a result it may be
   706  	// possible to have two IDNs that appear identical to the user where the
   707  	// ASCII-only version causes an error downstream whereas the non-ASCII
   708  	// version does not.
   709  	// Note that for correct ASCII IDNs ToASCII will only do considerably more
   710  	// work, but it will not cause an allocation.
   711  	if isASCII(v) {
   712  		return v, nil
   713  	}
   714  	return idna.Lookup.ToASCII(v)
   715  }
   716  
   717  // cleanHost cleans up the host sent in request's Host header.
   718  //
   719  // It both strips anything after '/' or ' ', and puts the value
   720  // into Punycode form, if necessary.
   721  //
   722  // Ideally we'd clean the Host header according to the spec:
   723  //   https://tools.ietf.org/html/rfc7230#section-5.4 (Host = uri-host [ ":" port ]")
   724  //   https://tools.ietf.org/html/rfc7230#section-2.7 (uri-host -> rfc3986's host)
   725  //   https://tools.ietf.org/html/rfc3986#section-3.2.2 (definition of host)
   726  // But practically, what we are trying to avoid is the situation in
   727  // issue 11206, where a malformed Host header used in the proxy context
   728  // would create a bad request. So it is enough to just truncate at the
   729  // first offending character.
   730  func cleanHost(in string) string {
   731  	if i := strings.IndexAny(in, " /"); i != -1 {
   732  		in = in[:i]
   733  	}
   734  	host, port, err := net.SplitHostPort(in)
   735  	if err != nil { // input was just a host
   736  		a, err := idnaASCII(in)
   737  		if err != nil {
   738  			return in // garbage in, garbage out
   739  		}
   740  		return a
   741  	}
   742  	a, err := idnaASCII(host)
   743  	if err != nil {
   744  		return in // garbage in, garbage out
   745  	}
   746  	return net.JoinHostPort(a, port)
   747  }
   748  
   749  // removeZone removes IPv6 zone identifier from host.
   750  // E.g., "[fe80::1%en0]:8080" to "[fe80::1]:8080"
   751  func removeZone(host string) string {
   752  	if !strings.HasPrefix(host, "[") {
   753  		return host
   754  	}
   755  	i := strings.LastIndex(host, "]")
   756  	if i < 0 {
   757  		return host
   758  	}
   759  	j := strings.LastIndex(host[:i], "%")
   760  	if j < 0 {
   761  		return host
   762  	}
   763  	return host[:j] + host[i:]
   764  }
   765  
   766  // ParseHTTPVersion parses a HTTP version string.
   767  // "HTTP/1.0" returns (1, 0, true).
   768  func ParseHTTPVersion(vers string) (major, minor int, ok bool) {
   769  	const Big = 1000000 // arbitrary upper bound
   770  	switch vers {
   771  	case "HTTP/1.1":
   772  		return 1, 1, true
   773  	case "HTTP/1.0":
   774  		return 1, 0, true
   775  	}
   776  	if !strings.HasPrefix(vers, "HTTP/") {
   777  		return 0, 0, false
   778  	}
   779  	dot := strings.Index(vers, ".")
   780  	if dot < 0 {
   781  		return 0, 0, false
   782  	}
   783  	major, err := strconv.Atoi(vers[5:dot])
   784  	if err != nil || major < 0 || major > Big {
   785  		return 0, 0, false
   786  	}
   787  	minor, err = strconv.Atoi(vers[dot+1:])
   788  	if err != nil || minor < 0 || minor > Big {
   789  		return 0, 0, false
   790  	}
   791  	return major, minor, true
   792  }
   793  
   794  func validMethod(method string) bool {
   795  	/*
   796  	     Method         = "OPTIONS"                ; Section 9.2
   797  	                    | "GET"                    ; Section 9.3
   798  	                    | "HEAD"                   ; Section 9.4
   799  	                    | "POST"                   ; Section 9.5
   800  	                    | "PUT"                    ; Section 9.6
   801  	                    | "DELETE"                 ; Section 9.7
   802  	                    | "TRACE"                  ; Section 9.8
   803  	                    | "CONNECT"                ; Section 9.9
   804  	                    | extension-method
   805  	   extension-method = token
   806  	     token          = 1*<any CHAR except CTLs or separators>
   807  	*/
   808  	return len(method) > 0 && strings.IndexFunc(method, isNotToken) == -1
   809  }
   810  
   811  // NewRequest wraps NewRequestWithContext using the background context.
   812  func NewRequest(method, url string, body io.Reader) (*Request, error) {
   813  	return NewRequestWithContext(context.Background(), method, url, body)
   814  }
   815  
   816  // NewRequestWithContext returns a new Request given a method, URL, and
   817  // optional body.
   818  //
   819  // If the provided body is also an io.Closer, the returned
   820  // Request.Body is set to body and will be closed by the Client
   821  // methods Do, Post, and PostForm, and Transport.RoundTrip.
   822  //
   823  // NewRequestWithContext returns a Request suitable for use with
   824  // Client.Do or Transport.RoundTrip. To create a request for use with
   825  // testing a Server Handler, either use the NewRequest function in the
   826  // net/http/httptest package, use ReadRequest, or manually update the
   827  // Request fields. For an outgoing client request, the context
   828  // controls the entire lifetime of a request and its response:
   829  // obtaining a connection, sending the request, and reading the
   830  // response headers and body. See the Request type's documentation for
   831  // the difference between inbound and outbound request fields.
   832  //
   833  // If body is of type *bytes.Buffer, *bytes.Reader, or
   834  // *strings.Reader, the returned request's ContentLength is set to its
   835  // exact value (instead of -1), GetBody is populated (so 307 and 308
   836  // redirects can replay the body), and Body is set to NoBody if the
   837  // ContentLength is 0.
   838  func NewRequestWithContext(ctx context.Context, method, url string, body io.Reader) (*Request, error) {
   839  	if method == "" {
   840  		// We document that "" means "GET" for Request.Method, and people have
   841  		// relied on that from NewRequest, so keep that working.
   842  		// We still enforce validMethod for non-empty methods.
   843  		method = "GET"
   844  	}
   845  	if !validMethod(method) {
   846  		return nil, fmt.Errorf("net/http: invalid method %q", method)
   847  	}
   848  	if ctx == nil {
   849  		return nil, errors.New("net/http: nil Context")
   850  	}
   851  	u, err := parseURL(url) // Just url.Parse (url is shadowed for godoc).
   852  	if err != nil {
   853  		return nil, err
   854  	}
   855  	rc, ok := body.(io.ReadCloser)
   856  	if !ok && body != nil {
   857  		rc = ioutil.NopCloser(body)
   858  	}
   859  	// The host's colon:port should be normalized. See Issue 14836.
   860  	u.Host = removeEmptyPort(u.Host)
   861  	req := &Request{
   862  		ctx:        ctx,
   863  		Method:     method,
   864  		URL:        u,
   865  		Proto:      "HTTP/1.1",
   866  		ProtoMajor: 1,
   867  		ProtoMinor: 1,
   868  		Header:     make(Header),
   869  		Body:       rc,
   870  		Host:       u.Host,
   871  	}
   872  	if body != nil {
   873  		switch v := body.(type) {
   874  		case *bytes.Buffer:
   875  			req.ContentLength = int64(v.Len())
   876  			buf := v.Bytes()
   877  			req.GetBody = func() (io.ReadCloser, error) {
   878  				r := bytes.NewReader(buf)
   879  				return ioutil.NopCloser(r), nil
   880  			}
   881  		case *bytes.Reader:
   882  			req.ContentLength = int64(v.Len())
   883  			snapshot := *v
   884  			req.GetBody = func() (io.ReadCloser, error) {
   885  				r := snapshot
   886  				return ioutil.NopCloser(&r), nil
   887  			}
   888  		case *strings.Reader:
   889  			req.ContentLength = int64(v.Len())
   890  			snapshot := *v
   891  			req.GetBody = func() (io.ReadCloser, error) {
   892  				r := snapshot
   893  				return ioutil.NopCloser(&r), nil
   894  			}
   895  		default:
   896  			// This is where we'd set it to -1 (at least
   897  			// if body != NoBody) to mean unknown, but
   898  			// that broke people during the Go 1.8 testing
   899  			// period. People depend on it being 0 I
   900  			// guess. Maybe retry later. See Issue 18117.
   901  		}
   902  		// For client requests, Request.ContentLength of 0
   903  		// means either actually 0, or unknown. The only way
   904  		// to explicitly say that the ContentLength is zero is
   905  		// to set the Body to nil. But turns out too much code
   906  		// depends on NewRequest returning a non-nil Body,
   907  		// so we use a well-known ReadCloser variable instead
   908  		// and have the http package also treat that sentinel
   909  		// variable to mean explicitly zero.
   910  		if req.GetBody != nil && req.ContentLength == 0 {
   911  			req.Body = NoBody
   912  			req.GetBody = func() (io.ReadCloser, error) { return NoBody, nil }
   913  		}
   914  	}
   915  
   916  	return req, nil
   917  }
   918  
   919  // BasicAuth returns the username and password provided in the request's
   920  // Authorization header, if the request uses HTTP Basic Authentication.
   921  // See RFC 2617, Section 2.
   922  func (r *Request) BasicAuth() (username, password string, ok bool) {
   923  	auth := r.Header.Get("Authorization")
   924  	if auth == "" {
   925  		return
   926  	}
   927  	return parseBasicAuth(auth)
   928  }
   929  
   930  // parseBasicAuth parses an HTTP Basic Authentication string.
   931  // "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==" returns ("Aladdin", "open sesame", true).
   932  func parseBasicAuth(auth string) (username, password string, ok bool) {
   933  	const prefix = "Basic "
   934  	// Case insensitive prefix match. See Issue 22736.
   935  	if len(auth) < len(prefix) || !strings.EqualFold(auth[:len(prefix)], prefix) {
   936  		return
   937  	}
   938  	c, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
   939  	if err != nil {
   940  		return
   941  	}
   942  	cs := string(c)
   943  	s := strings.IndexByte(cs, ':')
   944  	if s < 0 {
   945  		return
   946  	}
   947  	return cs[:s], cs[s+1:], true
   948  }
   949  
   950  // SetBasicAuth sets the request's Authorization header to use HTTP
   951  // Basic Authentication with the provided username and password.
   952  //
   953  // With HTTP Basic Authentication the provided username and password
   954  // are not encrypted.
   955  //
   956  // Some protocols may impose additional requirements on pre-escaping the
   957  // username and password. For instance, when used with OAuth2, both arguments
   958  // must be URL encoded first with url.QueryEscape.
   959  func (r *Request) SetBasicAuth(username, password string) {
   960  	r.Header.Set("Authorization", "Basic "+basicAuth(username, password))
   961  }
   962  
   963  // parseRequestLine parses "GET /foo HTTP/1.1" into its three parts.
   964  func parseRequestLine(line string) (method, requestURI, proto string, ok bool) {
   965  	s1 := strings.Index(line, " ")
   966  	s2 := strings.Index(line[s1+1:], " ")
   967  	if s1 < 0 || s2 < 0 {
   968  		return
   969  	}
   970  	s2 += s1 + 1
   971  	return line[:s1], line[s1+1 : s2], line[s2+1:], true
   972  }
   973  
   974  var textprotoReaderPool sync.Pool
   975  
   976  func newTextprotoReader(br *bufio.Reader) *textproto.Reader {
   977  	if v := textprotoReaderPool.Get(); v != nil {
   978  		tr := v.(*textproto.Reader)
   979  		tr.R = br
   980  		return tr
   981  	}
   982  	return textproto.NewReader(br)
   983  }
   984  
   985  func putTextprotoReader(r *textproto.Reader) {
   986  	r.R = nil
   987  	textprotoReaderPool.Put(r)
   988  }
   989  
   990  // ReadRequest reads and parses an incoming request from b.
   991  //
   992  // ReadRequest is a low-level function and should only be used for
   993  // specialized applications; most code should use the Server to read
   994  // requests and handle them via the Handler interface. ReadRequest
   995  // only supports HTTP/1.x requests. For HTTP/2, use golang.org/x/net/http2.
   996  func ReadRequest(b *bufio.Reader) (*Request, error) {
   997  	return readRequest(b, deleteHostHeader)
   998  }
   999  
  1000  // Constants for readRequest's deleteHostHeader parameter.
  1001  const (
  1002  	deleteHostHeader = true
  1003  	keepHostHeader   = false
  1004  )
  1005  
  1006  func readRequest(b *bufio.Reader, deleteHostHeader bool) (req *Request, err error) {
  1007  	tp := newTextprotoReader(b)
  1008  	req = new(Request)
  1009  
  1010  	// First line: GET /index.html HTTP/1.0
  1011  	var s string
  1012  	if s, err = tp.ReadLine(); err != nil {
  1013  		return nil, err
  1014  	}
  1015  	defer func() {
  1016  		putTextprotoReader(tp)
  1017  		if err == io.EOF {
  1018  			err = io.ErrUnexpectedEOF
  1019  		}
  1020  	}()
  1021  
  1022  	var ok bool
  1023  	req.Method, req.RequestURI, req.Proto, ok = parseRequestLine(s)
  1024  	if !ok {
  1025  		return nil, &badStringError{"malformed HTTP request", s}
  1026  	}
  1027  	if !validMethod(req.Method) {
  1028  		return nil, &badStringError{"invalid method", req.Method}
  1029  	}
  1030  	rawurl := req.RequestURI
  1031  	if req.ProtoMajor, req.ProtoMinor, ok = ParseHTTPVersion(req.Proto); !ok {
  1032  		return nil, &badStringError{"malformed HTTP version", req.Proto}
  1033  	}
  1034  
  1035  	// CONNECT requests are used two different ways, and neither uses a full URL:
  1036  	// The standard use is to tunnel HTTPS through an HTTP proxy.
  1037  	// It looks like "CONNECT www.google.com:443 HTTP/1.1", and the parameter is
  1038  	// just the authority section of a URL. This information should go in req.URL.Host.
  1039  	//
  1040  	// The net/rpc package also uses CONNECT, but there the parameter is a path
  1041  	// that starts with a slash. It can be parsed with the regular URL parser,
  1042  	// and the path will end up in req.URL.Path, where it needs to be in order for
  1043  	// RPC to work.
  1044  	justAuthority := req.Method == "CONNECT" && !strings.HasPrefix(rawurl, "/")
  1045  	if justAuthority {
  1046  		rawurl = "http://" + rawurl
  1047  	}
  1048  
  1049  	if req.URL, err = url.ParseRequestURI(rawurl); err != nil {
  1050  		return nil, err
  1051  	}
  1052  
  1053  	if justAuthority {
  1054  		// Strip the bogus "http://" back off.
  1055  		req.URL.Scheme = ""
  1056  	}
  1057  
  1058  	// Subsequent lines: Key: value.
  1059  	mimeHeader, err := tp.ReadMIMEHeader()
  1060  	if err != nil {
  1061  		return nil, err
  1062  	}
  1063  	req.Header = Header(mimeHeader)
  1064  
  1065  	// RFC 7230, section 5.3: Must treat
  1066  	//	GET /index.html HTTP/1.1
  1067  	//	Host: www.google.com
  1068  	// and
  1069  	//	GET http://www.google.com/index.html HTTP/1.1
  1070  	//	Host: doesntmatter
  1071  	// the same. In the second case, any Host line is ignored.
  1072  	req.Host = req.URL.Host
  1073  	if req.Host == "" {
  1074  		req.Host = req.Header.get("Host")
  1075  	}
  1076  	if deleteHostHeader {
  1077  		delete(req.Header, "Host")
  1078  	}
  1079  
  1080  	fixPragmaCacheControl(req.Header)
  1081  
  1082  	req.Close = shouldClose(req.ProtoMajor, req.ProtoMinor, req.Header, false)
  1083  
  1084  	err = readTransfer(req, b)
  1085  	if err != nil {
  1086  		return nil, err
  1087  	}
  1088  
  1089  	if req.isH2Upgrade() {
  1090  		// Because it's neither chunked, nor declared:
  1091  		req.ContentLength = -1
  1092  
  1093  		// We want to give handlers a chance to hijack the
  1094  		// connection, but we need to prevent the Server from
  1095  		// dealing with the connection further if it's not
  1096  		// hijacked. Set Close to ensure that:
  1097  		req.Close = true
  1098  	}
  1099  	return req, nil
  1100  }
  1101  
  1102  // MaxBytesReader is similar to io.LimitReader but is intended for
  1103  // limiting the size of incoming request bodies. In contrast to
  1104  // io.LimitReader, MaxBytesReader's result is a ReadCloser, returns a
  1105  // non-EOF error for a Read beyond the limit, and closes the
  1106  // underlying reader when its Close method is called.
  1107  //
  1108  // MaxBytesReader prevents clients from accidentally or maliciously
  1109  // sending a large request and wasting server resources.
  1110  func MaxBytesReader(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser {
  1111  	return &maxBytesReader{w: w, r: r, n: n}
  1112  }
  1113  
  1114  type maxBytesReader struct {
  1115  	w   ResponseWriter
  1116  	r   io.ReadCloser // underlying reader
  1117  	n   int64         // max bytes remaining
  1118  	err error         // sticky error
  1119  }
  1120  
  1121  func (l *maxBytesReader) Read(p []byte) (n int, err error) {
  1122  	if l.err != nil {
  1123  		return 0, l.err
  1124  	}
  1125  	if len(p) == 0 {
  1126  		return 0, nil
  1127  	}
  1128  	// If they asked for a 32KB byte read but only 5 bytes are
  1129  	// remaining, no need to read 32KB. 6 bytes will answer the
  1130  	// question of the whether we hit the limit or go past it.
  1131  	if int64(len(p)) > l.n+1 {
  1132  		p = p[:l.n+1]
  1133  	}
  1134  	n, err = l.r.Read(p)
  1135  
  1136  	if int64(n) <= l.n {
  1137  		l.n -= int64(n)
  1138  		l.err = err
  1139  		return n, err
  1140  	}
  1141  
  1142  	n = int(l.n)
  1143  	l.n = 0
  1144  
  1145  	// The server code and client code both use
  1146  	// maxBytesReader. This "requestTooLarge" check is
  1147  	// only used by the server code. To prevent binaries
  1148  	// which only using the HTTP Client code (such as
  1149  	// cmd/go) from also linking in the HTTP server, don't
  1150  	// use a static type assertion to the server
  1151  	// "*response" type. Check this interface instead:
  1152  	type requestTooLarger interface {
  1153  		requestTooLarge()
  1154  	}
  1155  	if res, ok := l.w.(requestTooLarger); ok {
  1156  		res.requestTooLarge()
  1157  	}
  1158  	l.err = errors.New("http: request body too large")
  1159  	return n, l.err
  1160  }
  1161  
  1162  func (l *maxBytesReader) Close() error {
  1163  	return l.r.Close()
  1164  }
  1165  
  1166  func copyValues(dst, src url.Values) {
  1167  	for k, vs := range src {
  1168  		for _, value := range vs {
  1169  			dst.Add(k, value)
  1170  		}
  1171  	}
  1172  }
  1173  
  1174  func parsePostForm(r *Request) (vs url.Values, err error) {
  1175  	if r.Body == nil {
  1176  		err = errors.New("missing form body")
  1177  		return
  1178  	}
  1179  	ct := r.Header.Get("Content-Type")
  1180  	// RFC 7231, section 3.1.1.5 - empty type
  1181  	//   MAY be treated as application/octet-stream
  1182  	if ct == "" {
  1183  		ct = "application/octet-stream"
  1184  	}
  1185  	ct, _, err = mime.ParseMediaType(ct)
  1186  	switch {
  1187  	case ct == "application/x-www-form-urlencoded":
  1188  		var reader io.Reader = r.Body
  1189  		maxFormSize := int64(1<<63 - 1)
  1190  		if _, ok := r.Body.(*maxBytesReader); !ok {
  1191  			maxFormSize = int64(10 << 20) // 10 MB is a lot of text.
  1192  			reader = io.LimitReader(r.Body, maxFormSize+1)
  1193  		}
  1194  		b, e := ioutil.ReadAll(reader)
  1195  		if e != nil {
  1196  			if err == nil {
  1197  				err = e
  1198  			}
  1199  			break
  1200  		}
  1201  		if int64(len(b)) > maxFormSize {
  1202  			err = errors.New("http: POST too large")
  1203  			return
  1204  		}
  1205  		vs, e = url.ParseQuery(string(b))
  1206  		if err == nil {
  1207  			err = e
  1208  		}
  1209  	case ct == "multipart/form-data":
  1210  		// handled by ParseMultipartForm (which is calling us, or should be)
  1211  		// TODO(bradfitz): there are too many possible
  1212  		// orders to call too many functions here.
  1213  		// Clean this up and write more tests.
  1214  		// request_test.go contains the start of this,
  1215  		// in TestParseMultipartFormOrder and others.
  1216  	}
  1217  	return
  1218  }
  1219  
  1220  // ParseForm populates r.Form and r.PostForm.
  1221  //
  1222  // For all requests, ParseForm parses the raw query from the URL and updates
  1223  // r.Form.
  1224  //
  1225  // For POST, PUT, and PATCH requests, it also parses the request body as a form
  1226  // and puts the results into both r.PostForm and r.Form. Request body parameters
  1227  // take precedence over URL query string values in r.Form.
  1228  //
  1229  // For other HTTP methods, or when the Content-Type is not
  1230  // application/x-www-form-urlencoded, the request Body is not read, and
  1231  // r.PostForm is initialized to a non-nil, empty value.
  1232  //
  1233  // If the request Body's size has not already been limited by MaxBytesReader,
  1234  // the size is capped at 10MB.
  1235  //
  1236  // ParseMultipartForm calls ParseForm automatically.
  1237  // ParseForm is idempotent.
  1238  func (r *Request) ParseForm() error {
  1239  	var err error
  1240  	if r.PostForm == nil {
  1241  		if r.Method == "POST" || r.Method == "PUT" || r.Method == "PATCH" {
  1242  			r.PostForm, err = parsePostForm(r)
  1243  		}
  1244  		if r.PostForm == nil {
  1245  			r.PostForm = make(url.Values)
  1246  		}
  1247  	}
  1248  	if r.Form == nil {
  1249  		if len(r.PostForm) > 0 {
  1250  			r.Form = make(url.Values)
  1251  			copyValues(r.Form, r.PostForm)
  1252  		}
  1253  		var newValues url.Values
  1254  		if r.URL != nil {
  1255  			var e error
  1256  			newValues, e = url.ParseQuery(r.URL.RawQuery)
  1257  			if err == nil {
  1258  				err = e
  1259  			}
  1260  		}
  1261  		if newValues == nil {
  1262  			newValues = make(url.Values)
  1263  		}
  1264  		if r.Form == nil {
  1265  			r.Form = newValues
  1266  		} else {
  1267  			copyValues(r.Form, newValues)
  1268  		}
  1269  	}
  1270  	return err
  1271  }
  1272  
  1273  // ParseMultipartForm parses a request body as multipart/form-data.
  1274  // The whole request body is parsed and up to a total of maxMemory bytes of
  1275  // its file parts are stored in memory, with the remainder stored on
  1276  // disk in temporary files.
  1277  // ParseMultipartForm calls ParseForm if necessary.
  1278  // After one call to ParseMultipartForm, subsequent calls have no effect.
  1279  func (r *Request) ParseMultipartForm(maxMemory int64) error {
  1280  	if r.MultipartForm == multipartByReader {
  1281  		return errors.New("http: multipart handled by MultipartReader")
  1282  	}
  1283  	if r.Form == nil {
  1284  		err := r.ParseForm()
  1285  		if err != nil {
  1286  			return err
  1287  		}
  1288  	}
  1289  	if r.MultipartForm != nil {
  1290  		return nil
  1291  	}
  1292  
  1293  	mr, err := r.multipartReader(false)
  1294  	if err != nil {
  1295  		return err
  1296  	}
  1297  
  1298  	f, err := mr.ReadForm(maxMemory)
  1299  	if err != nil {
  1300  		return err
  1301  	}
  1302  
  1303  	if r.PostForm == nil {
  1304  		r.PostForm = make(url.Values)
  1305  	}
  1306  	for k, v := range f.Value {
  1307  		r.Form[k] = append(r.Form[k], v...)
  1308  		// r.PostForm should also be populated. See Issue 9305.
  1309  		r.PostForm[k] = append(r.PostForm[k], v...)
  1310  	}
  1311  
  1312  	r.MultipartForm = f
  1313  
  1314  	return nil
  1315  }
  1316  
  1317  // FormValue returns the first value for the named component of the query.
  1318  // POST and PUT body parameters take precedence over URL query string values.
  1319  // FormValue calls ParseMultipartForm and ParseForm if necessary and ignores
  1320  // any errors returned by these functions.
  1321  // If key is not present, FormValue returns the empty string.
  1322  // To access multiple values of the same key, call ParseForm and
  1323  // then inspect Request.Form directly.
  1324  func (r *Request) FormValue(key string) string {
  1325  	if r.Form == nil {
  1326  		r.ParseMultipartForm(defaultMaxMemory)
  1327  	}
  1328  	if vs := r.Form[key]; len(vs) > 0 {
  1329  		return vs[0]
  1330  	}
  1331  	return ""
  1332  }
  1333  
  1334  // PostFormValue returns the first value for the named component of the POST,
  1335  // PATCH, or PUT request body. URL query parameters are ignored.
  1336  // PostFormValue calls ParseMultipartForm and ParseForm if necessary and ignores
  1337  // any errors returned by these functions.
  1338  // If key is not present, PostFormValue returns the empty string.
  1339  func (r *Request) PostFormValue(key string) string {
  1340  	if r.PostForm == nil {
  1341  		r.ParseMultipartForm(defaultMaxMemory)
  1342  	}
  1343  	if vs := r.PostForm[key]; len(vs) > 0 {
  1344  		return vs[0]
  1345  	}
  1346  	return ""
  1347  }
  1348  
  1349  // FormFile returns the first file for the provided form key.
  1350  // FormFile calls ParseMultipartForm and ParseForm if necessary.
  1351  func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, error) {
  1352  	if r.MultipartForm == multipartByReader {
  1353  		return nil, nil, errors.New("http: multipart handled by MultipartReader")
  1354  	}
  1355  	if r.MultipartForm == nil {
  1356  		err := r.ParseMultipartForm(defaultMaxMemory)
  1357  		if err != nil {
  1358  			return nil, nil, err
  1359  		}
  1360  	}
  1361  	if r.MultipartForm != nil && r.MultipartForm.File != nil {
  1362  		if fhs := r.MultipartForm.File[key]; len(fhs) > 0 {
  1363  			f, err := fhs[0].Open()
  1364  			return f, fhs[0], err
  1365  		}
  1366  	}
  1367  	return nil, nil, ErrMissingFile
  1368  }
  1369  
  1370  func (r *Request) expectsContinue() bool {
  1371  	return hasToken(r.Header.get("Expect"), "100-continue")
  1372  }
  1373  
  1374  func (r *Request) wantsHttp10KeepAlive() bool {
  1375  	if r.ProtoMajor != 1 || r.ProtoMinor != 0 {
  1376  		return false
  1377  	}
  1378  	return hasToken(r.Header.get("Connection"), "keep-alive")
  1379  }
  1380  
  1381  func (r *Request) wantsClose() bool {
  1382  	if r.Close {
  1383  		return true
  1384  	}
  1385  	return hasToken(r.Header.get("Connection"), "close")
  1386  }
  1387  
  1388  func (r *Request) closeBody() {
  1389  	if r.Body != nil {
  1390  		r.Body.Close()
  1391  	}
  1392  }
  1393  
  1394  func (r *Request) isReplayable() bool {
  1395  	if r.Body == nil || r.Body == NoBody || r.GetBody != nil {
  1396  		switch valueOrDefault(r.Method, "GET") {
  1397  		case "GET", "HEAD", "OPTIONS", "TRACE":
  1398  			return true
  1399  		}
  1400  		// The Idempotency-Key, while non-standard, is widely used to
  1401  		// mean a POST or other request is idempotent. See
  1402  		// https://golang.org/issue/19943#issuecomment-421092421
  1403  		if r.Header.has("Idempotency-Key") || r.Header.has("X-Idempotency-Key") {
  1404  			return true
  1405  		}
  1406  	}
  1407  	return false
  1408  }
  1409  
  1410  // outgoingLength reports the Content-Length of this outgoing (Client) request.
  1411  // It maps 0 into -1 (unknown) when the Body is non-nil.
  1412  func (r *Request) outgoingLength() int64 {
  1413  	if r.Body == nil || r.Body == NoBody {
  1414  		return 0
  1415  	}
  1416  	if r.ContentLength != 0 {
  1417  		return r.ContentLength
  1418  	}
  1419  	return -1
  1420  }
  1421  
  1422  // requestMethodUsuallyLacksBody reports whether the given request
  1423  // method is one that typically does not involve a request body.
  1424  // This is used by the Transport (via
  1425  // transferWriter.shouldSendChunkedRequestBody) to determine whether
  1426  // we try to test-read a byte from a non-nil Request.Body when
  1427  // Request.outgoingLength() returns -1. See the comments in
  1428  // shouldSendChunkedRequestBody.
  1429  func requestMethodUsuallyLacksBody(method string) bool {
  1430  	switch method {
  1431  	case "GET", "HEAD", "DELETE", "OPTIONS", "PROPFIND", "SEARCH":
  1432  		return true
  1433  	}
  1434  	return false
  1435  }
  1436  
  1437  // requiresHTTP1 reports whether this request requires being sent on
  1438  // an HTTP/1 connection.
  1439  func (r *Request) requiresHTTP1() bool {
  1440  	return hasToken(r.Header.Get("Connection"), "upgrade") &&
  1441  		strings.EqualFold(r.Header.Get("Upgrade"), "websocket")
  1442  }
  1443  

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