diff options
Diffstat (limited to 'gcc-4.8.1/libgo/go/net/http/transport.go')
| -rw-r--r-- | gcc-4.8.1/libgo/go/net/http/transport.go | 906 |
1 files changed, 0 insertions, 906 deletions
diff --git a/gcc-4.8.1/libgo/go/net/http/transport.go b/gcc-4.8.1/libgo/go/net/http/transport.go deleted file mode 100644 index 98e198e78..000000000 --- a/gcc-4.8.1/libgo/go/net/http/transport.go +++ /dev/null @@ -1,906 +0,0 @@ -// Copyright 2011 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// HTTP client implementation. See RFC 2616. -// -// This is the low-level Transport implementation of RoundTripper. -// The high-level interface is in client.go. - -package http - -import ( - "bufio" - "compress/gzip" - "crypto/tls" - "encoding/base64" - "errors" - "fmt" - "io" - "io/ioutil" - "log" - "net" - "net/url" - "os" - "strings" - "sync" - "time" -) - -// DefaultTransport is the default implementation of Transport and is -// used by DefaultClient. It establishes network connections as needed -// and caches them for reuse by subsequent calls. It uses HTTP proxies -// as directed by the $HTTP_PROXY and $NO_PROXY (or $http_proxy and -// $no_proxy) environment variables. -var DefaultTransport RoundTripper = &Transport{Proxy: ProxyFromEnvironment} - -// DefaultMaxIdleConnsPerHost is the default value of Transport's -// MaxIdleConnsPerHost. -const DefaultMaxIdleConnsPerHost = 2 - -// Transport is an implementation of RoundTripper that supports http, -// https, and http proxies (for either http or https with CONNECT). -// Transport can also cache connections for future re-use. -type Transport struct { - idleLk sync.Mutex - idleConn map[string][]*persistConn - altLk sync.RWMutex - altProto map[string]RoundTripper // nil or map of URI scheme => RoundTripper - - // TODO: tunable on global max cached connections - // TODO: tunable on timeout on cached connections - // TODO: optional pipelining - - // Proxy specifies a function to return a proxy for a given - // Request. If the function returns a non-nil error, the - // request is aborted with the provided error. - // If Proxy is nil or returns a nil *URL, no proxy is used. - Proxy func(*Request) (*url.URL, error) - - // Dial specifies the dial function for creating TCP - // connections. - // If Dial is nil, net.Dial is used. - Dial func(net, addr string) (c net.Conn, err error) - - // TLSClientConfig specifies the TLS configuration to use with - // tls.Client. If nil, the default configuration is used. - TLSClientConfig *tls.Config - - DisableKeepAlives bool - DisableCompression bool - - // MaxIdleConnsPerHost, if non-zero, controls the maximum idle - // (keep-alive) to keep per-host. If zero, - // DefaultMaxIdleConnsPerHost is used. - MaxIdleConnsPerHost int -} - -// ProxyFromEnvironment returns the URL of the proxy to use for a -// given request, as indicated by the environment variables -// $HTTP_PROXY and $NO_PROXY (or $http_proxy and $no_proxy). -// An error is returned if the proxy environment is invalid. -// A nil URL and nil error are returned if no proxy is defined in the -// environment, or a proxy should not be used for the given request. -func ProxyFromEnvironment(req *Request) (*url.URL, error) { - proxy := getenvEitherCase("HTTP_PROXY") - if proxy == "" { - return nil, nil - } - if !useProxy(canonicalAddr(req.URL)) { - return nil, nil - } - proxyURL, err := url.Parse(proxy) - if err != nil || !strings.HasPrefix(proxyURL.Scheme, "http") { - if u, err := url.Parse("http://" + proxy); err == nil { - proxyURL = u - err = nil - } - } - if err != nil { - return nil, fmt.Errorf("invalid proxy address %q: %v", proxy, err) - } - return proxyURL, nil -} - -// ProxyURL returns a proxy function (for use in a Transport) -// that always returns the same URL. -func ProxyURL(fixedURL *url.URL) func(*Request) (*url.URL, error) { - return func(*Request) (*url.URL, error) { - return fixedURL, nil - } -} - -// transportRequest is a wrapper around a *Request that adds -// optional extra headers to write. -type transportRequest struct { - *Request // original request, not to be mutated - extra Header // extra headers to write, or nil -} - -func (tr *transportRequest) extraHeaders() Header { - if tr.extra == nil { - tr.extra = make(Header) - } - return tr.extra -} - -// RoundTrip implements the RoundTripper interface. -func (t *Transport) RoundTrip(req *Request) (resp *Response, err error) { - if req.URL == nil { - return nil, errors.New("http: nil Request.URL") - } - if req.Header == nil { - return nil, errors.New("http: nil Request.Header") - } - if req.URL.Scheme != "http" && req.URL.Scheme != "https" { - t.altLk.RLock() - var rt RoundTripper - if t.altProto != nil { - rt = t.altProto[req.URL.Scheme] - } - t.altLk.RUnlock() - if rt == nil { - return nil, &badStringError{"unsupported protocol scheme", req.URL.Scheme} - } - return rt.RoundTrip(req) - } - if req.URL.Host == "" { - return nil, errors.New("http: no Host in request URL") - } - treq := &transportRequest{Request: req} - cm, err := t.connectMethodForRequest(treq) - if err != nil { - return nil, err - } - - // Get the cached or newly-created connection to either the - // host (for http or https), the http proxy, or the http proxy - // pre-CONNECTed to https server. In any case, we'll be ready - // to send it requests. - pconn, err := t.getConn(cm) - if err != nil { - return nil, err - } - - return pconn.roundTrip(treq) -} - -// RegisterProtocol registers a new protocol with scheme. -// The Transport will pass requests using the given scheme to rt. -// It is rt's responsibility to simulate HTTP request semantics. -// -// RegisterProtocol can be used by other packages to provide -// implementations of protocol schemes like "ftp" or "file". -func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper) { - if scheme == "http" || scheme == "https" { - panic("protocol " + scheme + " already registered") - } - t.altLk.Lock() - defer t.altLk.Unlock() - if t.altProto == nil { - t.altProto = make(map[string]RoundTripper) - } - if _, exists := t.altProto[scheme]; exists { - panic("protocol " + scheme + " already registered") - } - t.altProto[scheme] = rt -} - -// CloseIdleConnections closes any connections which were previously -// connected from previous requests but are now sitting idle in -// a "keep-alive" state. It does not interrupt any connections currently -// in use. -func (t *Transport) CloseIdleConnections() { - t.idleLk.Lock() - m := t.idleConn - t.idleConn = nil - t.idleLk.Unlock() - if m == nil { - return - } - for _, conns := range m { - for _, pconn := range conns { - pconn.close() - } - } -} - -// -// Private implementation past this point. -// - -func getenvEitherCase(k string) string { - if v := os.Getenv(strings.ToUpper(k)); v != "" { - return v - } - return os.Getenv(strings.ToLower(k)) -} - -func (t *Transport) connectMethodForRequest(treq *transportRequest) (*connectMethod, error) { - cm := &connectMethod{ - targetScheme: treq.URL.Scheme, - targetAddr: canonicalAddr(treq.URL), - } - if t.Proxy != nil { - var err error - cm.proxyURL, err = t.Proxy(treq.Request) - if err != nil { - return nil, err - } - } - return cm, nil -} - -// proxyAuth returns the Proxy-Authorization header to set -// on requests, if applicable. -func (cm *connectMethod) proxyAuth() string { - if cm.proxyURL == nil { - return "" - } - if u := cm.proxyURL.User; u != nil { - return "Basic " + base64.URLEncoding.EncodeToString([]byte(u.String())) - } - return "" -} - -// putIdleConn adds pconn to the list of idle persistent connections awaiting -// a new request. -// If pconn is no longer needed or not in a good state, putIdleConn -// returns false. -func (t *Transport) putIdleConn(pconn *persistConn) bool { - if t.DisableKeepAlives || t.MaxIdleConnsPerHost < 0 { - pconn.close() - return false - } - if pconn.isBroken() { - return false - } - key := pconn.cacheKey - max := t.MaxIdleConnsPerHost - if max == 0 { - max = DefaultMaxIdleConnsPerHost - } - t.idleLk.Lock() - if t.idleConn == nil { - t.idleConn = make(map[string][]*persistConn) - } - if len(t.idleConn[key]) >= max { - t.idleLk.Unlock() - pconn.close() - return false - } - for _, exist := range t.idleConn[key] { - if exist == pconn { - log.Fatalf("dup idle pconn %p in freelist", pconn) - } - } - t.idleConn[key] = append(t.idleConn[key], pconn) - t.idleLk.Unlock() - return true -} - -func (t *Transport) getIdleConn(cm *connectMethod) (pconn *persistConn) { - key := cm.String() - t.idleLk.Lock() - defer t.idleLk.Unlock() - if t.idleConn == nil { - return nil - } - for { - pconns, ok := t.idleConn[key] - if !ok { - return nil - } - if len(pconns) == 1 { - pconn = pconns[0] - delete(t.idleConn, key) - } else { - // 2 or more cached connections; pop last - // TODO: queue? - pconn = pconns[len(pconns)-1] - t.idleConn[key] = pconns[0 : len(pconns)-1] - } - if !pconn.isBroken() { - return - } - } - panic("unreachable") -} - -func (t *Transport) dial(network, addr string) (c net.Conn, err error) { - if t.Dial != nil { - return t.Dial(network, addr) - } - return net.Dial(network, addr) -} - -// getConn dials and creates a new persistConn to the target as -// specified in the connectMethod. This includes doing a proxy CONNECT -// and/or setting up TLS. If this doesn't return an error, the persistConn -// is ready to write requests to. -func (t *Transport) getConn(cm *connectMethod) (*persistConn, error) { - if pc := t.getIdleConn(cm); pc != nil { - return pc, nil - } - - conn, err := t.dial("tcp", cm.addr()) - if err != nil { - if cm.proxyURL != nil { - err = fmt.Errorf("http: error connecting to proxy %s: %v", cm.proxyURL, err) - } - return nil, err - } - - pa := cm.proxyAuth() - - pconn := &persistConn{ - t: t, - cacheKey: cm.String(), - conn: conn, - reqch: make(chan requestAndChan, 50), - writech: make(chan writeRequest, 50), - closech: make(chan struct{}), - } - - switch { - case cm.proxyURL == nil: - // Do nothing. - case cm.targetScheme == "http": - pconn.isProxy = true - if pa != "" { - pconn.mutateHeaderFunc = func(h Header) { - h.Set("Proxy-Authorization", pa) - } - } - case cm.targetScheme == "https": - connectReq := &Request{ - Method: "CONNECT", - URL: &url.URL{Opaque: cm.targetAddr}, - Host: cm.targetAddr, - Header: make(Header), - } - if pa != "" { - connectReq.Header.Set("Proxy-Authorization", pa) - } - connectReq.Write(conn) - - // Read response. - // Okay to use and discard buffered reader here, because - // TLS server will not speak until spoken to. - br := bufio.NewReader(conn) - resp, err := ReadResponse(br, connectReq) - if err != nil { - conn.Close() - return nil, err - } - if resp.StatusCode != 200 { - f := strings.SplitN(resp.Status, " ", 2) - conn.Close() - return nil, errors.New(f[1]) - } - } - - if cm.targetScheme == "https" { - // Initiate TLS and check remote host name against certificate. - cfg := t.TLSClientConfig - if cfg == nil || cfg.ServerName == "" { - host := cm.tlsHost() - if cfg == nil { - cfg = &tls.Config{ServerName: host} - } else { - clone := *cfg // shallow clone - clone.ServerName = host - cfg = &clone - } - } - conn = tls.Client(conn, cfg) - if err = conn.(*tls.Conn).Handshake(); err != nil { - return nil, err - } - if t.TLSClientConfig == nil || !t.TLSClientConfig.InsecureSkipVerify { - if err = conn.(*tls.Conn).VerifyHostname(cm.tlsHost()); err != nil { - return nil, err - } - } - pconn.conn = conn - } - - pconn.br = bufio.NewReader(pconn.conn) - pconn.bw = bufio.NewWriter(pconn.conn) - go pconn.readLoop() - go pconn.writeLoop() - return pconn, nil -} - -// useProxy returns true if requests to addr should use a proxy, -// according to the NO_PROXY or no_proxy environment variable. -// addr is always a canonicalAddr with a host and port. -func useProxy(addr string) bool { - if len(addr) == 0 { - return true - } - host, _, err := net.SplitHostPort(addr) - if err != nil { - return false - } - if host == "localhost" { - return false - } - if ip := net.ParseIP(host); ip != nil { - if ip.IsLoopback() { - return false - } - } - - no_proxy := getenvEitherCase("NO_PROXY") - if no_proxy == "*" { - return false - } - - addr = strings.ToLower(strings.TrimSpace(addr)) - if hasPort(addr) { - addr = addr[:strings.LastIndex(addr, ":")] - } - - for _, p := range strings.Split(no_proxy, ",") { - p = strings.ToLower(strings.TrimSpace(p)) - if len(p) == 0 { - continue - } - if hasPort(p) { - p = p[:strings.LastIndex(p, ":")] - } - if addr == p { - return false - } - if p[0] == '.' && (strings.HasSuffix(addr, p) || addr == p[1:]) { - // no_proxy ".foo.com" matches "bar.foo.com" or "foo.com" - return false - } - if p[0] != '.' && strings.HasSuffix(addr, p) && addr[len(addr)-len(p)-1] == '.' { - // no_proxy "foo.com" matches "bar.foo.com" - return false - } - } - return true -} - -// connectMethod is the map key (in its String form) for keeping persistent -// TCP connections alive for subsequent HTTP requests. -// -// A connect method may be of the following types: -// -// Cache key form Description -// ----------------- ------------------------- -// ||http|foo.com http directly to server, no proxy -// ||https|foo.com https directly to server, no proxy -// http://proxy.com|https|foo.com http to proxy, then CONNECT to foo.com -// http://proxy.com|http http to proxy, http to anywhere after that -// -// Note: no support to https to the proxy yet. -// -type connectMethod struct { - proxyURL *url.URL // nil for no proxy, else full proxy URL - targetScheme string // "http" or "https" - targetAddr string // Not used if proxy + http targetScheme (4th example in table) -} - -func (ck *connectMethod) String() string { - proxyStr := "" - targetAddr := ck.targetAddr - if ck.proxyURL != nil { - proxyStr = ck.proxyURL.String() - if ck.targetScheme == "http" { - targetAddr = "" - } - } - return strings.Join([]string{proxyStr, ck.targetScheme, targetAddr}, "|") -} - -// addr returns the first hop "host:port" to which we need to TCP connect. -func (cm *connectMethod) addr() string { - if cm.proxyURL != nil { - return canonicalAddr(cm.proxyURL) - } - return cm.targetAddr -} - -// tlsHost returns the host name to match against the peer's -// TLS certificate. -func (cm *connectMethod) tlsHost() string { - h := cm.targetAddr - if hasPort(h) { - h = h[:strings.LastIndex(h, ":")] - } - return h -} - -// persistConn wraps a connection, usually a persistent one -// (but may be used for non-keep-alive requests as well) -type persistConn struct { - t *Transport - cacheKey string // its connectMethod.String() - conn net.Conn - closed bool // whether conn has been closed - br *bufio.Reader // from conn - bw *bufio.Writer // to conn - reqch chan requestAndChan // written by roundTrip; read by readLoop - writech chan writeRequest // written by roundTrip; read by writeLoop - closech chan struct{} // broadcast close when readLoop (TCP connection) closes - isProxy bool - - // mutateHeaderFunc is an optional func to modify extra - // headers on each outbound request before it's written. (the - // original Request given to RoundTrip is not modified) - mutateHeaderFunc func(Header) - - lk sync.Mutex // guards numExpectedResponses and broken - numExpectedResponses int - broken bool // an error has happened on this connection; marked broken so it's not reused. -} - -func (pc *persistConn) isBroken() bool { - pc.lk.Lock() - b := pc.broken - pc.lk.Unlock() - return b -} - -var remoteSideClosedFunc func(error) bool // or nil to use default - -func remoteSideClosed(err error) bool { - if err == io.EOF { - return true - } - if remoteSideClosedFunc != nil { - return remoteSideClosedFunc(err) - } - return false -} - -func (pc *persistConn) readLoop() { - defer close(pc.closech) - alive := true - var lastbody io.ReadCloser // last response body, if any, read on this connection - - for alive { - pb, err := pc.br.Peek(1) - - pc.lk.Lock() - if pc.numExpectedResponses == 0 { - pc.closeLocked() - pc.lk.Unlock() - if len(pb) > 0 { - log.Printf("Unsolicited response received on idle HTTP channel starting with %q; err=%v", - string(pb), err) - } - return - } - pc.lk.Unlock() - - rc := <-pc.reqch - - // Advance past the previous response's body, if the - // caller hasn't done so. - if lastbody != nil { - lastbody.Close() // assumed idempotent - lastbody = nil - } - - var resp *Response - if err == nil { - resp, err = ReadResponse(pc.br, rc.req) - } - - if err != nil { - pc.close() - } else { - hasBody := rc.req.Method != "HEAD" && resp.ContentLength != 0 - if rc.addedGzip && hasBody && resp.Header.Get("Content-Encoding") == "gzip" { - resp.Header.Del("Content-Encoding") - resp.Header.Del("Content-Length") - resp.ContentLength = -1 - gzReader, zerr := gzip.NewReader(resp.Body) - if zerr != nil { - pc.close() - err = zerr - } else { - resp.Body = &readFirstCloseBoth{&discardOnCloseReadCloser{gzReader}, resp.Body} - } - } - resp.Body = &bodyEOFSignal{body: resp.Body} - } - - if err != nil || resp.Close || rc.req.Close { - alive = false - } - - hasBody := resp != nil && rc.req.Method != "HEAD" && resp.ContentLength != 0 - var waitForBodyRead chan bool - if hasBody { - lastbody = resp.Body - waitForBodyRead = make(chan bool, 1) - resp.Body.(*bodyEOFSignal).fn = func(err error) { - alive1 := alive - if err != nil { - alive1 = false - } - if alive1 && !pc.t.putIdleConn(pc) { - alive1 = false - } - if !alive1 || pc.isBroken() { - pc.close() - } - waitForBodyRead <- alive1 - } - } - - if alive && !hasBody { - // When there's no response body, we immediately - // reuse the TCP connection (putIdleConn), but - // we need to prevent ClientConn.Read from - // closing the Response.Body on the next - // loop, otherwise it might close the body - // before the client code has had a chance to - // read it (even though it'll just be 0, EOF). - lastbody = nil - - if !pc.t.putIdleConn(pc) { - alive = false - } - } - - rc.ch <- responseAndError{resp, err} - - // Wait for the just-returned response body to be fully consumed - // before we race and peek on the underlying bufio reader. - if waitForBodyRead != nil { - alive = <-waitForBodyRead - } - - if !alive { - pc.close() - } - } -} - -func (pc *persistConn) writeLoop() { - for { - select { - case wr := <-pc.writech: - if pc.isBroken() { - wr.ch <- errors.New("http: can't write HTTP request on broken connection") - continue - } - err := wr.req.Request.write(pc.bw, pc.isProxy, wr.req.extra) - if err == nil { - err = pc.bw.Flush() - } - if err != nil { - pc.markBroken() - } - wr.ch <- err - case <-pc.closech: - return - } - } -} - -type responseAndError struct { - res *Response - err error -} - -type requestAndChan struct { - req *Request - ch chan responseAndError - - // did the Transport (as opposed to the client code) add an - // Accept-Encoding gzip header? only if it we set it do - // we transparently decode the gzip. - addedGzip bool -} - -// A writeRequest is sent by the readLoop's goroutine to the -// writeLoop's goroutine to write a request while the read loop -// concurrently waits on both the write response and the server's -// reply. -type writeRequest struct { - req *transportRequest - ch chan<- error -} - -func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err error) { - if pc.mutateHeaderFunc != nil { - pc.mutateHeaderFunc(req.extraHeaders()) - } - - // Ask for a compressed version if the caller didn't set their - // own value for Accept-Encoding. We only attempted to - // uncompress the gzip stream if we were the layer that - // requested it. - requestedGzip := false - if !pc.t.DisableCompression && req.Header.Get("Accept-Encoding") == "" { - // Request gzip only, not deflate. Deflate is ambiguous and - // not as universally supported anyway. - // See: http://www.gzip.org/zlib/zlib_faq.html#faq38 - requestedGzip = true - req.extraHeaders().Set("Accept-Encoding", "gzip") - } - - pc.lk.Lock() - pc.numExpectedResponses++ - pc.lk.Unlock() - - // Write the request concurrently with waiting for a response, - // in case the server decides to reply before reading our full - // request body. - writeErrCh := make(chan error, 1) - pc.writech <- writeRequest{req, writeErrCh} - - resc := make(chan responseAndError, 1) - pc.reqch <- requestAndChan{req.Request, resc, requestedGzip} - - var re responseAndError - var pconnDeadCh = pc.closech - var failTicker <-chan time.Time -WaitResponse: - for { - select { - case err := <-writeErrCh: - if err != nil { - re = responseAndError{nil, err} - pc.close() - break WaitResponse - } - case <-pconnDeadCh: - // The persist connection is dead. This shouldn't - // usually happen (only with Connection: close responses - // with no response bodies), but if it does happen it - // means either a) the remote server hung up on us - // prematurely, or b) the readLoop sent us a response & - // closed its closech at roughly the same time, and we - // selected this case first, in which case a response - // might still be coming soon. - // - // We can't avoid the select race in b) by using a unbuffered - // resc channel instead, because then goroutines can - // leak if we exit due to other errors. - pconnDeadCh = nil // avoid spinning - failTicker = time.After(100 * time.Millisecond) // arbitrary time to wait for resc - case <-failTicker: - re = responseAndError{nil, errors.New("net/http: transport closed before response was received")} - break WaitResponse - case re = <-resc: - break WaitResponse - } - } - - pc.lk.Lock() - pc.numExpectedResponses-- - pc.lk.Unlock() - - return re.res, re.err -} - -// markBroken marks a connection as broken (so it's not reused). -// It differs from close in that it doesn't close the underlying -// connection for use when it's still being read. -func (pc *persistConn) markBroken() { - pc.lk.Lock() - defer pc.lk.Unlock() - pc.broken = true -} - -func (pc *persistConn) close() { - pc.lk.Lock() - defer pc.lk.Unlock() - pc.closeLocked() -} - -func (pc *persistConn) closeLocked() { - pc.broken = true - if !pc.closed { - pc.conn.Close() - pc.closed = true - } - pc.mutateHeaderFunc = nil -} - -var portMap = map[string]string{ - "http": "80", - "https": "443", -} - -// canonicalAddr returns url.Host but always with a ":port" suffix -func canonicalAddr(url *url.URL) string { - addr := url.Host - if !hasPort(addr) { - return addr + ":" + portMap[url.Scheme] - } - return addr -} - -// bodyEOFSignal wraps a ReadCloser but runs fn (if non-nil) at most -// once, right before its final (error-producing) Read or Close call -// returns. -type bodyEOFSignal struct { - body io.ReadCloser - mu sync.Mutex // guards closed, rerr and fn - closed bool // whether Close has been called - rerr error // sticky Read error - fn func(error) // error will be nil on Read io.EOF -} - -func (es *bodyEOFSignal) Read(p []byte) (n int, err error) { - es.mu.Lock() - closed, rerr := es.closed, es.rerr - es.mu.Unlock() - if closed { - return 0, errors.New("http: read on closed response body") - } - if rerr != nil { - return 0, rerr - } - - n, err = es.body.Read(p) - if err != nil { - es.mu.Lock() - defer es.mu.Unlock() - if es.rerr == nil { - es.rerr = err - } - es.condfn(err) - } - return -} - -func (es *bodyEOFSignal) Close() error { - es.mu.Lock() - defer es.mu.Unlock() - if es.closed { - return nil - } - es.closed = true - err := es.body.Close() - es.condfn(err) - return err -} - -// caller must hold es.mu. -func (es *bodyEOFSignal) condfn(err error) { - if es.fn == nil { - return - } - if err == io.EOF { - err = nil - } - es.fn(err) - es.fn = nil -} - -type readFirstCloseBoth struct { - io.ReadCloser - io.Closer -} - -func (r *readFirstCloseBoth) Close() error { - if err := r.ReadCloser.Close(); err != nil { - r.Closer.Close() - return err - } - if err := r.Closer.Close(); err != nil { - return err - } - return nil -} - -// discardOnCloseReadCloser consumes all its input on Close. -type discardOnCloseReadCloser struct { - io.ReadCloser -} - -func (d *discardOnCloseReadCloser) Close() error { - io.Copy(ioutil.Discard, d.ReadCloser) // ignore errors; likely invalid or already closed - return d.ReadCloser.Close() -} |