Source file src/pkg/net/http/request.go

     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		"crypto/tls"
    13		"encoding/base64"
    14		"errors"
    15		"fmt"
    16		"io"
    17		"io/ioutil"
    18		"mime"
    19		"mime/multipart"
    20		"net/textproto"
    21		"net/url"
    22		"strconv"
    23		"strings"
    24	)
    25	
    26	const (
    27		maxValueLength   = 4096
    28		maxHeaderLines   = 1024
    29		chunkSize        = 4 << 10  // 4 KB chunks
    30		defaultMaxMemory = 32 << 20 // 32 MB
    31	)
    32	
    33	// ErrMissingFile is returned by FormFile when the provided file field name
    34	// is either not present in the request or not a file field.
    35	var ErrMissingFile = errors.New("http: no such file")
    36	
    37	// HTTP request parsing errors.
    38	type ProtocolError struct {
    39		ErrorString string
    40	}
    41	
    42	func (err *ProtocolError) Error() string { return err.ErrorString }
    43	
    44	var (
    45		ErrHeaderTooLong        = &ProtocolError{"header too long"}
    46		ErrShortBody            = &ProtocolError{"entity body too short"}
    47		ErrNotSupported         = &ProtocolError{"feature not supported"}
    48		ErrUnexpectedTrailer    = &ProtocolError{"trailer header without chunked transfer encoding"}
    49		ErrMissingContentLength = &ProtocolError{"missing ContentLength in HEAD response"}
    50		ErrNotMultipart         = &ProtocolError{"request Content-Type isn't multipart/form-data"}
    51		ErrMissingBoundary      = &ProtocolError{"no multipart boundary param in Content-Type"}
    52	)
    53	
    54	type badStringError struct {
    55		what string
    56		str  string
    57	}
    58	
    59	func (e *badStringError) Error() string { return fmt.Sprintf("%s %q", e.what, e.str) }
    60	
    61	// Headers that Request.Write handles itself and should be skipped.
    62	var reqWriteExcludeHeader = map[string]bool{
    63		"Host":              true, // not in Header map anyway
    64		"User-Agent":        true,
    65		"Content-Length":    true,
    66		"Transfer-Encoding": true,
    67		"Trailer":           true,
    68	}
    69	
    70	// A Request represents an HTTP request received by a server
    71	// or to be sent by a client.
    72	type Request struct {
    73		Method string // GET, POST, PUT, etc.
    74	
    75		// URL is created from the URI supplied on the Request-Line
    76		// as stored in RequestURI.
    77		//
    78		// For most requests, fields other than Path and RawQuery
    79		// will be empty. (See RFC 2616, Section 5.1.2)
    80		URL *url.URL
    81	
    82		// The protocol version for incoming requests.
    83		// Outgoing requests always use HTTP/1.1.
    84		Proto      string // "HTTP/1.0"
    85		ProtoMajor int    // 1
    86		ProtoMinor int    // 0
    87	
    88		// A header maps request lines to their values.
    89		// If the header says
    90		//
    91		//	accept-encoding: gzip, deflate
    92		//	Accept-Language: en-us
    93		//	Connection: keep-alive
    94		//
    95		// then
    96		//
    97		//	Header = map[string][]string{
    98		//		"Accept-Encoding": {"gzip, deflate"},
    99		//		"Accept-Language": {"en-us"},
   100		//		"Connection": {"keep-alive"},
   101		//	}
   102		//
   103		// HTTP defines that header names are case-insensitive.
   104		// The request parser implements this by canonicalizing the
   105		// name, making the first character and any characters
   106		// following a hyphen uppercase and the rest lowercase.
   107		Header Header
   108	
   109		// The message body.
   110		Body io.ReadCloser
   111	
   112		// ContentLength records the length of the associated content.
   113		// The value -1 indicates that the length is unknown.
   114		// Values >= 0 indicate that the given number of bytes may
   115		// be read from Body.
   116		// For outgoing requests, a value of 0 means unknown if Body is not nil.
   117		ContentLength int64
   118	
   119		// TransferEncoding lists the transfer encodings from outermost to
   120		// innermost. An empty list denotes the "identity" encoding.
   121		// TransferEncoding can usually be ignored; chunked encoding is
   122		// automatically added and removed as necessary when sending and
   123		// receiving requests.
   124		TransferEncoding []string
   125	
   126		// Close indicates whether to close the connection after
   127		// replying to this request.
   128		Close bool
   129	
   130		// The host on which the URL is sought.
   131		// Per RFC 2616, this is either the value of the Host: header
   132		// or the host name given in the URL itself.
   133		// It may be of the form "host:port".
   134		Host string
   135	
   136		// Form contains the parsed form data, including both the URL
   137		// field's query parameters and the POST or PUT form data.
   138		// This field is only available after ParseForm is called.
   139		// The HTTP client ignores Form and uses Body instead.
   140		Form url.Values
   141	
   142		// PostForm contains the parsed form data from POST or PUT
   143		// body parameters.
   144		// This field is only available after ParseForm is called.
   145		// The HTTP client ignores PostForm and uses Body instead.
   146		PostForm url.Values
   147	
   148		// MultipartForm is the parsed multipart form, including file uploads.
   149		// This field is only available after ParseMultipartForm is called.
   150		// The HTTP client ignores MultipartForm and uses Body instead.
   151		MultipartForm *multipart.Form
   152	
   153		// Trailer maps trailer keys to values.  Like for Header, if the
   154		// response has multiple trailer lines with the same key, they will be
   155		// concatenated, delimited by commas.
   156		// For server requests, Trailer is only populated after Body has been
   157		// closed or fully consumed.
   158		// Trailer support is only partially complete.
   159		Trailer Header
   160	
   161		// RemoteAddr allows HTTP servers and other software to record
   162		// the network address that sent the request, usually for
   163		// logging. This field is not filled in by ReadRequest and
   164		// has no defined format. The HTTP server in this package
   165		// sets RemoteAddr to an "IP:port" address before invoking a
   166		// handler.
   167		// This field is ignored by the HTTP client.
   168		RemoteAddr string
   169	
   170		// RequestURI is the unmodified Request-URI of the
   171		// Request-Line (RFC 2616, Section 5.1) as sent by the client
   172		// to a server. Usually the URL field should be used instead.
   173		// It is an error to set this field in an HTTP client request.
   174		RequestURI string
   175	
   176		// TLS allows HTTP servers and other software to record
   177		// information about the TLS connection on which the request
   178		// was received. This field is not filled in by ReadRequest.
   179		// The HTTP server in this package sets the field for
   180		// TLS-enabled connections before invoking a handler;
   181		// otherwise it leaves the field nil.
   182		// This field is ignored by the HTTP client.
   183		TLS *tls.ConnectionState
   184	}
   185	
   186	// ProtoAtLeast returns whether the HTTP protocol used
   187	// in the request is at least major.minor.
   188	func (r *Request) ProtoAtLeast(major, minor int) bool {
   189		return r.ProtoMajor > major ||
   190			r.ProtoMajor == major && r.ProtoMinor >= minor
   191	}
   192	
   193	// UserAgent returns the client's User-Agent, if sent in the request.
   194	func (r *Request) UserAgent() string {
   195		return r.Header.Get("User-Agent")
   196	}
   197	
   198	// Cookies parses and returns the HTTP cookies sent with the request.
   199	func (r *Request) Cookies() []*Cookie {
   200		return readCookies(r.Header, "")
   201	}
   202	
   203	var ErrNoCookie = errors.New("http: named cookie not present")
   204	
   205	// Cookie returns the named cookie provided in the request or
   206	// ErrNoCookie if not found.
   207	func (r *Request) Cookie(name string) (*Cookie, error) {
   208		for _, c := range readCookies(r.Header, name) {
   209			return c, nil
   210		}
   211		return nil, ErrNoCookie
   212	}
   213	
   214	// AddCookie adds a cookie to the request.  Per RFC 6265 section 5.4,
   215	// AddCookie does not attach more than one Cookie header field.  That
   216	// means all cookies, if any, are written into the same line,
   217	// separated by semicolon.
   218	func (r *Request) AddCookie(c *Cookie) {
   219		s := fmt.Sprintf("%s=%s", sanitizeName(c.Name), sanitizeValue(c.Value))
   220		if c := r.Header.Get("Cookie"); c != "" {
   221			r.Header.Set("Cookie", c+"; "+s)
   222		} else {
   223			r.Header.Set("Cookie", s)
   224		}
   225	}
   226	
   227	// Referer returns the referring URL, if sent in the request.
   228	//
   229	// Referer is misspelled as in the request itself, a mistake from the
   230	// earliest days of HTTP.  This value can also be fetched from the
   231	// Header map as Header["Referer"]; the benefit of making it available
   232	// as a method is that the compiler can diagnose programs that use the
   233	// alternate (correct English) spelling req.Referrer() but cannot
   234	// diagnose programs that use Header["Referrer"].
   235	func (r *Request) Referer() string {
   236		return r.Header.Get("Referer")
   237	}
   238	
   239	// multipartByReader is a sentinel value.
   240	// Its presence in Request.MultipartForm indicates that parsing of the request
   241	// body has been handed off to a MultipartReader instead of ParseMultipartFrom.
   242	var multipartByReader = &multipart.Form{
   243		Value: make(map[string][]string),
   244		File:  make(map[string][]*multipart.FileHeader),
   245	}
   246	
   247	// MultipartReader returns a MIME multipart reader if this is a
   248	// multipart/form-data POST request, else returns nil and an error.
   249	// Use this function instead of ParseMultipartForm to
   250	// process the request body as a stream.
   251	func (r *Request) MultipartReader() (*multipart.Reader, error) {
   252		if r.MultipartForm == multipartByReader {
   253			return nil, errors.New("http: MultipartReader called twice")
   254		}
   255		if r.MultipartForm != nil {
   256			return nil, errors.New("http: multipart handled by ParseMultipartForm")
   257		}
   258		r.MultipartForm = multipartByReader
   259		return r.multipartReader()
   260	}
   261	
   262	func (r *Request) multipartReader() (*multipart.Reader, error) {
   263		v := r.Header.Get("Content-Type")
   264		if v == "" {
   265			return nil, ErrNotMultipart
   266		}
   267		d, params, err := mime.ParseMediaType(v)
   268		if err != nil || d != "multipart/form-data" {
   269			return nil, ErrNotMultipart
   270		}
   271		boundary, ok := params["boundary"]
   272		if !ok {
   273			return nil, ErrMissingBoundary
   274		}
   275		return multipart.NewReader(r.Body, boundary), nil
   276	}
   277	
   278	// Return value if nonempty, def otherwise.
   279	func valueOrDefault(value, def string) string {
   280		if value != "" {
   281			return value
   282		}
   283		return def
   284	}
   285	
   286	const defaultUserAgent = "Go 1.1 package http"
   287	
   288	// Write writes an HTTP/1.1 request -- header and body -- in wire format.
   289	// This method consults the following fields of the request:
   290	//	Host
   291	//	URL
   292	//	Method (defaults to "GET")
   293	//	Header
   294	//	ContentLength
   295	//	TransferEncoding
   296	//	Body
   297	//
   298	// If Body is present, Content-Length is <= 0 and TransferEncoding
   299	// hasn't been set to "identity", Write adds "Transfer-Encoding:
   300	// chunked" to the header. Body is closed after it is sent.
   301	func (r *Request) Write(w io.Writer) error {
   302		return r.write(w, false, nil)
   303	}
   304	
   305	// WriteProxy is like Write but writes the request in the form
   306	// expected by an HTTP proxy.  In particular, WriteProxy writes the
   307	// initial Request-URI line of the request with an absolute URI, per
   308	// section 5.1.2 of RFC 2616, including the scheme and host.
   309	// In either case, WriteProxy also writes a Host header, using
   310	// either r.Host or r.URL.Host.
   311	func (r *Request) WriteProxy(w io.Writer) error {
   312		return r.write(w, true, nil)
   313	}
   314	
   315	// extraHeaders may be nil
   316	func (req *Request) write(w io.Writer, usingProxy bool, extraHeaders Header) error {
   317		host := req.Host
   318		if host == "" {
   319			if req.URL == nil {
   320				return errors.New("http: Request.Write on Request with no Host or URL set")
   321			}
   322			host = req.URL.Host
   323		}
   324	
   325		ruri := req.URL.RequestURI()
   326		if usingProxy && req.URL.Scheme != "" && req.URL.Opaque == "" {
   327			ruri = req.URL.Scheme + "://" + host + ruri
   328		} else if req.Method == "CONNECT" && req.URL.Path == "" {
   329			// CONNECT requests normally give just the host and port, not a full URL.
   330			ruri = host
   331		}
   332		// TODO(bradfitz): escape at least newlines in ruri?
   333	
   334		// Wrap the writer in a bufio Writer if it's not already buffered.
   335		// Don't always call NewWriter, as that forces a bytes.Buffer
   336		// and other small bufio Writers to have a minimum 4k buffer
   337		// size.
   338		var bw *bufio.Writer
   339		if _, ok := w.(io.ByteWriter); !ok {
   340			bw = bufio.NewWriter(w)
   341			w = bw
   342		}
   343	
   344		fmt.Fprintf(w, "%s %s HTTP/1.1\r\n", valueOrDefault(req.Method, "GET"), ruri)
   345	
   346		// Header lines
   347		fmt.Fprintf(w, "Host: %s\r\n", host)
   348	
   349		// Use the defaultUserAgent unless the Header contains one, which
   350		// may be blank to not send the header.
   351		userAgent := defaultUserAgent
   352		if req.Header != nil {
   353			if ua := req.Header["User-Agent"]; len(ua) > 0 {
   354				userAgent = ua[0]
   355			}
   356		}
   357		if userAgent != "" {
   358			fmt.Fprintf(w, "User-Agent: %s\r\n", userAgent)
   359		}
   360	
   361		// Process Body,ContentLength,Close,Trailer
   362		tw, err := newTransferWriter(req)
   363		if err != nil {
   364			return err
   365		}
   366		err = tw.WriteHeader(w)
   367		if err != nil {
   368			return err
   369		}
   370	
   371		// TODO: split long values?  (If so, should share code with Conn.Write)
   372		err = req.Header.WriteSubset(w, reqWriteExcludeHeader)
   373		if err != nil {
   374			return err
   375		}
   376	
   377		if extraHeaders != nil {
   378			err = extraHeaders.Write(w)
   379			if err != nil {
   380				return err
   381			}
   382		}
   383	
   384		io.WriteString(w, "\r\n")
   385	
   386		// Write body and trailer
   387		err = tw.WriteBody(w)
   388		if err != nil {
   389			return err
   390		}
   391	
   392		if bw != nil {
   393			return bw.Flush()
   394		}
   395		return nil
   396	}
   397	
   398	// ParseHTTPVersion parses a HTTP version string.
   399	// "HTTP/1.0" returns (1, 0, true).
   400	func ParseHTTPVersion(vers string) (major, minor int, ok bool) {
   401		const Big = 1000000 // arbitrary upper bound
   402		switch vers {
   403		case "HTTP/1.1":
   404			return 1, 1, true
   405		case "HTTP/1.0":
   406			return 1, 0, true
   407		}
   408		if !strings.HasPrefix(vers, "HTTP/") {
   409			return 0, 0, false
   410		}
   411		dot := strings.Index(vers, ".")
   412		if dot < 0 {
   413			return 0, 0, false
   414		}
   415		major, err := strconv.Atoi(vers[5:dot])
   416		if err != nil || major < 0 || major > Big {
   417			return 0, 0, false
   418		}
   419		minor, err = strconv.Atoi(vers[dot+1:])
   420		if err != nil || minor < 0 || minor > Big {
   421			return 0, 0, false
   422		}
   423		return major, minor, true
   424	}
   425	
   426	// NewRequest returns a new Request given a method, URL, and optional body.
   427	func NewRequest(method, urlStr string, body io.Reader) (*Request, error) {
   428		u, err := url.Parse(urlStr)
   429		if err != nil {
   430			return nil, err
   431		}
   432		rc, ok := body.(io.ReadCloser)
   433		if !ok && body != nil {
   434			rc = ioutil.NopCloser(body)
   435		}
   436		req := &Request{
   437			Method:     method,
   438			URL:        u,
   439			Proto:      "HTTP/1.1",
   440			ProtoMajor: 1,
   441			ProtoMinor: 1,
   442			Header:     make(Header),
   443			Body:       rc,
   444			Host:       u.Host,
   445		}
   446		if body != nil {
   447			switch v := body.(type) {
   448			case *bytes.Buffer:
   449				req.ContentLength = int64(v.Len())
   450			case *bytes.Reader:
   451				req.ContentLength = int64(v.Len())
   452			case *strings.Reader:
   453				req.ContentLength = int64(v.Len())
   454			}
   455		}
   456	
   457		return req, nil
   458	}
   459	
   460	// SetBasicAuth sets the request's Authorization header to use HTTP
   461	// Basic Authentication with the provided username and password.
   462	//
   463	// With HTTP Basic Authentication the provided username and password
   464	// are not encrypted.
   465	func (r *Request) SetBasicAuth(username, password string) {
   466		s := username + ":" + password
   467		r.Header.Set("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(s)))
   468	}
   469	
   470	// parseRequestLine parses "GET /foo HTTP/1.1" into its three parts.
   471	func parseRequestLine(line string) (method, requestURI, proto string, ok bool) {
   472		s1 := strings.Index(line, " ")
   473		s2 := strings.Index(line[s1+1:], " ")
   474		if s1 < 0 || s2 < 0 {
   475			return
   476		}
   477		s2 += s1 + 1
   478		return line[:s1], line[s1+1 : s2], line[s2+1:], true
   479	}
   480	
   481	// TODO(bradfitz): use a sync.Cache when available
   482	var textprotoReaderCache = make(chan *textproto.Reader, 4)
   483	
   484	func newTextprotoReader(br *bufio.Reader) *textproto.Reader {
   485		select {
   486		case r := <-textprotoReaderCache:
   487			r.R = br
   488			return r
   489		default:
   490			return textproto.NewReader(br)
   491		}
   492	}
   493	
   494	func putTextprotoReader(r *textproto.Reader) {
   495		r.R = nil
   496		select {
   497		case textprotoReaderCache <- r:
   498		default:
   499		}
   500	}
   501	
   502	// ReadRequest reads and parses a request from b.
   503	func ReadRequest(b *bufio.Reader) (req *Request, err error) {
   504	
   505		tp := newTextprotoReader(b)
   506		req = new(Request)
   507	
   508		// First line: GET /index.html HTTP/1.0
   509		var s string
   510		if s, err = tp.ReadLine(); err != nil {
   511			return nil, err
   512		}
   513		defer func() {
   514			putTextprotoReader(tp)
   515			if err == io.EOF {
   516				err = io.ErrUnexpectedEOF
   517			}
   518		}()
   519	
   520		var ok bool
   521		req.Method, req.RequestURI, req.Proto, ok = parseRequestLine(s)
   522		if !ok {
   523			return nil, &badStringError{"malformed HTTP request", s}
   524		}
   525		rawurl := req.RequestURI
   526		if req.ProtoMajor, req.ProtoMinor, ok = ParseHTTPVersion(req.Proto); !ok {
   527			return nil, &badStringError{"malformed HTTP version", req.Proto}
   528		}
   529	
   530		// CONNECT requests are used two different ways, and neither uses a full URL:
   531		// The standard use is to tunnel HTTPS through an HTTP proxy.
   532		// It looks like "CONNECT www.google.com:443 HTTP/1.1", and the parameter is
   533		// just the authority section of a URL. This information should go in req.URL.Host.
   534		//
   535		// The net/rpc package also uses CONNECT, but there the parameter is a path
   536		// that starts with a slash. It can be parsed with the regular URL parser,
   537		// and the path will end up in req.URL.Path, where it needs to be in order for
   538		// RPC to work.
   539		justAuthority := req.Method == "CONNECT" && !strings.HasPrefix(rawurl, "/")
   540		if justAuthority {
   541			rawurl = "http://" + rawurl
   542		}
   543	
   544		if req.URL, err = url.ParseRequestURI(rawurl); err != nil {
   545			return nil, err
   546		}
   547	
   548		if justAuthority {
   549			// Strip the bogus "http://" back off.
   550			req.URL.Scheme = ""
   551		}
   552	
   553		// Subsequent lines: Key: value.
   554		mimeHeader, err := tp.ReadMIMEHeader()
   555		if err != nil {
   556			return nil, err
   557		}
   558		req.Header = Header(mimeHeader)
   559	
   560		// RFC2616: Must treat
   561		//	GET /index.html HTTP/1.1
   562		//	Host: www.google.com
   563		// and
   564		//	GET http://www.google.com/index.html HTTP/1.1
   565		//	Host: doesntmatter
   566		// the same.  In the second case, any Host line is ignored.
   567		req.Host = req.URL.Host
   568		if req.Host == "" {
   569			req.Host = req.Header.get("Host")
   570		}
   571		delete(req.Header, "Host")
   572	
   573		fixPragmaCacheControl(req.Header)
   574	
   575		// TODO: Parse specific header values:
   576		//	Accept
   577		//	Accept-Encoding
   578		//	Accept-Language
   579		//	Authorization
   580		//	Cache-Control
   581		//	Connection
   582		//	Date
   583		//	Expect
   584		//	From
   585		//	If-Match
   586		//	If-Modified-Since
   587		//	If-None-Match
   588		//	If-Range
   589		//	If-Unmodified-Since
   590		//	Max-Forwards
   591		//	Proxy-Authorization
   592		//	Referer [sic]
   593		//	TE (transfer-codings)
   594		//	Trailer
   595		//	Transfer-Encoding
   596		//	Upgrade
   597		//	User-Agent
   598		//	Via
   599		//	Warning
   600	
   601		err = readTransfer(req, b)
   602		if err != nil {
   603			return nil, err
   604		}
   605	
   606		return req, nil
   607	}
   608	
   609	// MaxBytesReader is similar to io.LimitReader but is intended for
   610	// limiting the size of incoming request bodies. In contrast to
   611	// io.LimitReader, MaxBytesReader's result is a ReadCloser, returns a
   612	// non-EOF error for a Read beyond the limit, and Closes the
   613	// underlying reader when its Close method is called.
   614	//
   615	// MaxBytesReader prevents clients from accidentally or maliciously
   616	// sending a large request and wasting server resources.
   617	func MaxBytesReader(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser {
   618		return &maxBytesReader{w: w, r: r, n: n}
   619	}
   620	
   621	type maxBytesReader struct {
   622		w       ResponseWriter
   623		r       io.ReadCloser // underlying reader
   624		n       int64         // max bytes remaining
   625		stopped bool
   626	}
   627	
   628	func (l *maxBytesReader) Read(p []byte) (n int, err error) {
   629		if l.n <= 0 {
   630			if !l.stopped {
   631				l.stopped = true
   632				if res, ok := l.w.(*response); ok {
   633					res.requestTooLarge()
   634				}
   635			}
   636			return 0, errors.New("http: request body too large")
   637		}
   638		if int64(len(p)) > l.n {
   639			p = p[:l.n]
   640		}
   641		n, err = l.r.Read(p)
   642		l.n -= int64(n)
   643		return
   644	}
   645	
   646	func (l *maxBytesReader) Close() error {
   647		return l.r.Close()
   648	}
   649	
   650	func copyValues(dst, src url.Values) {
   651		for k, vs := range src {
   652			for _, value := range vs {
   653				dst.Add(k, value)
   654			}
   655		}
   656	}
   657	
   658	func parsePostForm(r *Request) (vs url.Values, err error) {
   659		if r.Body == nil {
   660			err = errors.New("missing form body")
   661			return
   662		}
   663		ct := r.Header.Get("Content-Type")
   664		ct, _, err = mime.ParseMediaType(ct)
   665		switch {
   666		case ct == "application/x-www-form-urlencoded":
   667			var reader io.Reader = r.Body
   668			maxFormSize := int64(1<<63 - 1)
   669			if _, ok := r.Body.(*maxBytesReader); !ok {
   670				maxFormSize = int64(10 << 20) // 10 MB is a lot of text.
   671				reader = io.LimitReader(r.Body, maxFormSize+1)
   672			}
   673			b, e := ioutil.ReadAll(reader)
   674			if e != nil {
   675				if err == nil {
   676					err = e
   677				}
   678				break
   679			}
   680			if int64(len(b)) > maxFormSize {
   681				err = errors.New("http: POST too large")
   682				return
   683			}
   684			vs, e = url.ParseQuery(string(b))
   685			if err == nil {
   686				err = e
   687			}
   688		case ct == "multipart/form-data":
   689			// handled by ParseMultipartForm (which is calling us, or should be)
   690			// TODO(bradfitz): there are too many possible
   691			// orders to call too many functions here.
   692			// Clean this up and write more tests.
   693			// request_test.go contains the start of this,
   694			// in TestRequestMultipartCallOrder.
   695		}
   696		return
   697	}
   698	
   699	// ParseForm parses the raw query from the URL and updates r.Form.
   700	//
   701	// For POST or PUT requests, it also parses the request body as a form and
   702	// put the results into both r.PostForm and r.Form.
   703	// POST and PUT body parameters take precedence over URL query string values
   704	// in r.Form.
   705	//
   706	// If the request Body's size has not already been limited by MaxBytesReader,
   707	// the size is capped at 10MB.
   708	//
   709	// ParseMultipartForm calls ParseForm automatically.
   710	// It is idempotent.
   711	func (r *Request) ParseForm() error {
   712		var err error
   713		if r.PostForm == nil {
   714			if r.Method == "POST" || r.Method == "PUT" {
   715				r.PostForm, err = parsePostForm(r)
   716			}
   717			if r.PostForm == nil {
   718				r.PostForm = make(url.Values)
   719			}
   720		}
   721		if r.Form == nil {
   722			if len(r.PostForm) > 0 {
   723				r.Form = make(url.Values)
   724				copyValues(r.Form, r.PostForm)
   725			}
   726			var newValues url.Values
   727			if r.URL != nil {
   728				var e error
   729				newValues, e = url.ParseQuery(r.URL.RawQuery)
   730				if err == nil {
   731					err = e
   732				}
   733			}
   734			if newValues == nil {
   735				newValues = make(url.Values)
   736			}
   737			if r.Form == nil {
   738				r.Form = newValues
   739			} else {
   740				copyValues(r.Form, newValues)
   741			}
   742		}
   743		return err
   744	}
   745	
   746	// ParseMultipartForm parses a request body as multipart/form-data.
   747	// The whole request body is parsed and up to a total of maxMemory bytes of
   748	// its file parts are stored in memory, with the remainder stored on
   749	// disk in temporary files.
   750	// ParseMultipartForm calls ParseForm if necessary.
   751	// After one call to ParseMultipartForm, subsequent calls have no effect.
   752	func (r *Request) ParseMultipartForm(maxMemory int64) error {
   753		if r.MultipartForm == multipartByReader {
   754			return errors.New("http: multipart handled by MultipartReader")
   755		}
   756		if r.Form == nil {
   757			err := r.ParseForm()
   758			if err != nil {
   759				return err
   760			}
   761		}
   762		if r.MultipartForm != nil {
   763			return nil
   764		}
   765	
   766		mr, err := r.multipartReader()
   767		if err == ErrNotMultipart {
   768			return nil
   769		} else if err != nil {
   770			return err
   771		}
   772	
   773		f, err := mr.ReadForm(maxMemory)
   774		if err != nil {
   775			return err
   776		}
   777		for k, v := range f.Value {
   778			r.Form[k] = append(r.Form[k], v...)
   779		}
   780		r.MultipartForm = f
   781	
   782		return nil
   783	}
   784	
   785	// FormValue returns the first value for the named component of the query.
   786	// POST and PUT body parameters take precedence over URL query string values.
   787	// FormValue calls ParseMultipartForm and ParseForm if necessary.
   788	// To access multiple values of the same key use ParseForm.
   789	func (r *Request) FormValue(key string) string {
   790		if r.Form == nil {
   791			r.ParseMultipartForm(defaultMaxMemory)
   792		}
   793		if vs := r.Form[key]; len(vs) > 0 {
   794			return vs[0]
   795		}
   796		return ""
   797	}
   798	
   799	// PostFormValue returns the first value for the named component of the POST
   800	// or PUT request body. URL query parameters are ignored.
   801	// PostFormValue calls ParseMultipartForm and ParseForm if necessary.
   802	func (r *Request) PostFormValue(key string) string {
   803		if r.PostForm == nil {
   804			r.ParseMultipartForm(defaultMaxMemory)
   805		}
   806		if vs := r.PostForm[key]; len(vs) > 0 {
   807			return vs[0]
   808		}
   809		return ""
   810	}
   811	
   812	// FormFile returns the first file for the provided form key.
   813	// FormFile calls ParseMultipartForm and ParseForm if necessary.
   814	func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, error) {
   815		if r.MultipartForm == multipartByReader {
   816			return nil, nil, errors.New("http: multipart handled by MultipartReader")
   817		}
   818		if r.MultipartForm == nil {
   819			err := r.ParseMultipartForm(defaultMaxMemory)
   820			if err != nil {
   821				return nil, nil, err
   822			}
   823		}
   824		if r.MultipartForm != nil && r.MultipartForm.File != nil {
   825			if fhs := r.MultipartForm.File[key]; len(fhs) > 0 {
   826				f, err := fhs[0].Open()
   827				return f, fhs[0], err
   828			}
   829		}
   830		return nil, nil, ErrMissingFile
   831	}
   832	
   833	func (r *Request) expectsContinue() bool {
   834		return hasToken(r.Header.get("Expect"), "100-continue")
   835	}
   836	
   837	func (r *Request) wantsHttp10KeepAlive() bool {
   838		if r.ProtoMajor != 1 || r.ProtoMinor != 0 {
   839			return false
   840		}
   841		return hasToken(r.Header.get("Connection"), "keep-alive")
   842	}
   843	
   844	func (r *Request) wantsClose() bool {
   845		return hasToken(r.Header.get("Connection"), "close")
   846	}

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