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

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