src/net/http/httputil/dump.go - go - Git at Google

 // Copyright 2009 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.

 package httputil

 import (
 	"bufio"
 	"bytes"
 	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"net"
 	"net/http"
 	"net/url"
 	"strings"
 	"time"
 )

 // One of the copies, say from b to r2, could be avoided by using a more
 // elaborate trick where the other copy is made during Request/Response.Write.
 // This would complicate things too much, given that these functions are for
 // debugging only.
 func drainBody(b io.ReadCloser) (r1, r2 io.ReadCloser, err error) {
 	var buf bytes.Buffer
 	if _, err = buf.ReadFrom(b); err != nil {
 		return nil, b, err
 	}
 	if err = b.Close(); err != nil {
 		return nil, b, err
 	}
 	return ioutil.NopCloser(&buf), ioutil.NopCloser(bytes.NewReader(buf.Bytes())), nil
 }

 // dumpConn is a net.Conn which writes to Writer and reads from Reader
 type dumpConn struct {
 	io.Writer
 	io.Reader
 }

 func (c *dumpConn) Close() error                       { return nil }
 func (c *dumpConn) LocalAddr() net.Addr                { return nil }
 func (c *dumpConn) RemoteAddr() net.Addr               { return nil }
 func (c *dumpConn) SetDeadline(t time.Time) error      { return nil }
 func (c *dumpConn) SetReadDeadline(t time.Time) error  { return nil }
 func (c *dumpConn) SetWriteDeadline(t time.Time) error { return nil }

 type neverEnding byte

 func (b neverEnding) Read(p []byte) (n int, err error) {
 	for i := range p {
 		p[i] = byte(b)
 	}
 	return len(p), nil
 }

 // DumpRequestOut is like DumpRequest but for outgoing client requests. It
 // includes any headers that the standard http.Transport adds, such as
 // User-Agent.
 func DumpRequestOut(req *http.Request, body bool) ([]byte, error) {
 	save := req.Body
 	dummyBody := false
 	if !body || req.Body == nil {
 		req.Body = nil
 		if req.ContentLength != 0 {
 			req.Body = ioutil.NopCloser(io.LimitReader(neverEnding('x'), req.ContentLength))
 			dummyBody = true
 		}
 	} else {
 		var err error
 		save, req.Body, err = drainBody(req.Body)
 		if err != nil {
 			return nil, err
 		}
 	}

 	// Since we're using the actual Transport code to write the request,
 	// switch to http so the Transport doesn't try to do an SSL
 	// negotiation with our dumpConn and its bytes.Buffer & pipe.
 	// The wire format for https and http are the same, anyway.
 	reqSend := req
 	if req.URL.Scheme == "https" {
 		reqSend = new(http.Request)
 		*reqSend = *req
 		reqSend.URL = new(url.URL)
 		*reqSend.URL = *req.URL
 		reqSend.URL.Scheme = "http"
 	}

 	// Use the actual Transport code to record what we would send
 	// on the wire, but not using TCP.  Use a Transport with a
 	// custom dialer that returns a fake net.Conn that waits
 	// for the full input (and recording it), and then responds
 	// with a dummy response.
 	var buf bytes.Buffer // records the output
 	pr, pw := io.Pipe()
 	defer pr.Close()
 	defer pw.Close()
 	dr := &delegateReader{c: make(chan io.Reader)}

 	t := &http.Transport{
 		Dial: func(net, addr string) (net.Conn, error) {
 			return &dumpConn{io.MultiWriter(&buf, pw), dr}, nil
 		},
 	}
 	defer t.CloseIdleConnections()

 	// Wait for the request before replying with a dummy response:
 	go func() {
 		req, err := http.ReadRequest(bufio.NewReader(pr))
 		if err == nil {
 			// Ensure all the body is read; otherwise
 			// we'll get a partial dump.
 			io.Copy(ioutil.Discard, req.Body)
 			req.Body.Close()
 		}
 		dr.c <- strings.NewReader("HTTP/1.1 204 No Content\r\nConnection: close\r\n\r\n")
 	}()

 	_, err := t.RoundTrip(reqSend)

 	req.Body = save
 	if err != nil {
 		return nil, err
 	}
 	dump := buf.Bytes()

 	// If we used a dummy body above, remove it now.
 	// TODO: if the req.ContentLength is large, we allocate memory
 	// unnecessarily just to slice it off here. But this is just
 	// a debug function, so this is acceptable for now. We could
 	// discard the body earlier if this matters.
 	if dummyBody {
 		if i := bytes.Index(dump, []byte("\r\n\r\n")); i >= 0 {
 			dump = dump[:i+4]
 		}
 	}
 	return dump, nil
 }

 // delegateReader is a reader that delegates to another reader,
 // once it arrives on a channel.
 type delegateReader struct {
 	c chan io.Reader
 	r io.Reader // nil until received from c
 }

 func (r *delegateReader) Read(p []byte) (int, error) {
 	if r.r == nil {
 		r.r = <-r.c
 	}
 	return r.r.Read(p)
 }

 // Return value if nonempty, def otherwise.
 func valueOrDefault(value, def string) string {
 	if value != "" {
 		return value
 	}
 	return def
 }

 var reqWriteExcludeHeaderDump = map[string]bool{
 	"Host":              true, // not in Header map anyway
 	"Transfer-Encoding": true,
 	"Trailer":           true,
 }

 // DumpRequest returns the given request in its HTTP/1.x wire
 // representation. It should only be used by servers to debug client
 // requests. The returned representation is an approximation only;
 // some details of the initial request are lost while parsing it into
 // an http.Request. In particular, the order and case of header field
 // names are lost. The order of values in multi-valued headers is kept
 // intact. HTTP/2 requests are dumped in HTTP/1.x form, not in their
 // original binary representations.
 //
 // If body is true, DumpRequest also returns the body. To do so, it
 // consumes req.Body and then replaces it with a new io.ReadCloser
 // that yields the same bytes. If DumpRequest returns an error,
 // the state of req is undefined.
 //
 // The documentation for http.Request.Write details which fields
 // of req are included in the dump.
 func DumpRequest(req *http.Request, body bool) ([]byte, error) {
 	var err error
 	save := req.Body
 	if !body || req.Body == nil {
 		req.Body = nil
 	} else {
 		save, req.Body, err = drainBody(req.Body)
 		if err != nil {
 			return nil, err
 		}
 	}

 	var b bytes.Buffer

 	// By default, print out the unmodified req.RequestURI, which
 	// is always set for incoming server requests. But because we
 	// previously used req.URL.RequestURI and the docs weren't
 	// always so clear about when to use DumpRequest vs
 	// DumpRequestOut, fall back to the old way if the caller
 	// provides a non-server Request.
 	reqURI := req.RequestURI
 	if reqURI == "" {
 		reqURI = req.URL.RequestURI()
 	}

 	fmt.Fprintf(&b, "%s %s HTTP/%d.%d\r\n", valueOrDefault(req.Method, "GET"),
 		reqURI, req.ProtoMajor, req.ProtoMinor)

 	absRequestURI := strings.HasPrefix(req.RequestURI, "http://") || strings.HasPrefix(req.RequestURI, "https://")
 	if !absRequestURI {
 		host := req.Host
 		if host == "" && req.URL != nil {
 			host = req.URL.Host
 		}
 		if host != "" {
 			fmt.Fprintf(&b, "Host: %s\r\n", host)
 		}
 	}

 	chunked := len(req.TransferEncoding) > 0 && req.TransferEncoding[0] == "chunked"
 	if len(req.TransferEncoding) > 0 {
 		fmt.Fprintf(&b, "Transfer-Encoding: %s\r\n", strings.Join(req.TransferEncoding, ","))
 	}
 	if req.Close {
 		fmt.Fprintf(&b, "Connection: close\r\n")
 	}

 	err = req.Header.WriteSubset(&b, reqWriteExcludeHeaderDump)
 	if err != nil {
 		return nil, err
 	}

 	io.WriteString(&b, "\r\n")

 	if req.Body != nil {
 		var dest io.Writer = &b
 		if chunked {
 			dest = NewChunkedWriter(dest)
 		}
 		_, err = io.Copy(dest, req.Body)
 		if chunked {
 			dest.(io.Closer).Close()
 			io.WriteString(&b, "\r\n")
 		}
 	}

 	req.Body = save
 	if err != nil {
 		return nil, err
 	}
 	return b.Bytes(), nil
 }

 // errNoBody is a sentinel error value used by failureToReadBody so we
 // can detect that the lack of body was intentional.
 var errNoBody = errors.New("sentinel error value")

 // failureToReadBody is a io.ReadCloser that just returns errNoBody on
 // Read. It's swapped in when we don't actually want to consume
 // the body, but need a non-nil one, and want to distinguish the
 // error from reading the dummy body.
 type failureToReadBody struct{}

 func (failureToReadBody) Read([]byte) (int, error) { return 0, errNoBody }
 func (failureToReadBody) Close() error             { return nil }

 // emptyBody is an instance of empty reader.
 var emptyBody = ioutil.NopCloser(strings.NewReader(""))

 // DumpResponse is like DumpRequest but dumps a response.
 func DumpResponse(resp *http.Response, body bool) ([]byte, error) {
 	var b bytes.Buffer
 	var err error
 	save := resp.Body
 	savecl := resp.ContentLength

 	if !body {
 		// For content length of zero. Make sure the body is an empty
 		// reader, instead of returning error through failureToReadBody{}.
 		if resp.ContentLength == 0 {
 			resp.Body = emptyBody
 		} else {
 			resp.Body = failureToReadBody{}
 		}
 	} else if resp.Body == nil {
 		resp.Body = emptyBody
 	} else {
 		save, resp.Body, err = drainBody(resp.Body)
 		if err != nil {
 			return nil, err
 		}
 	}
 	err = resp.Write(&b)
 	if err == errNoBody {
 		err = nil
 	}
 	resp.Body = save
 	resp.ContentLength = savecl
 	if err != nil {
 		return nil, err
 	}
 	return b.Bytes(), nil
 }
	// Copyright 2009 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.

	package httputil

	import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"net/url"
	"strings"
	"time"
	)

	// One of the copies, say from b to r2, could be avoided by using a more
	// elaborate trick where the other copy is made during Request/Response.Write.
	// This would complicate things too much, given that these functions are for
	// debugging only.
	func drainBody(b io.ReadCloser) (r1, r2 io.ReadCloser, err error) {
	var buf bytes.Buffer
	if _, err = buf.ReadFrom(b); err != nil {
	return nil, b, err
	}
	if err = b.Close(); err != nil {
	return nil, b, err
	}
	return ioutil.NopCloser(&buf), ioutil.NopCloser(bytes.NewReader(buf.Bytes())), nil
	}

	// dumpConn is a net.Conn which writes to Writer and reads from Reader
	type dumpConn struct {
	io.Writer
	io.Reader
	}

	func (c *dumpConn) Close() error { return nil }
	func (c *dumpConn) LocalAddr() net.Addr { return nil }
	func (c *dumpConn) RemoteAddr() net.Addr { return nil }
	func (c *dumpConn) SetDeadline(t time.Time) error { return nil }
	func (c *dumpConn) SetReadDeadline(t time.Time) error { return nil }
	func (c *dumpConn) SetWriteDeadline(t time.Time) error { return nil }

	type neverEnding byte

	func (b neverEnding) Read(p []byte) (n int, err error) {
	for i := range p {
	p[i] = byte(b)
	}
	return len(p), nil
	}

	// DumpRequestOut is like DumpRequest but for outgoing client requests. It
	// includes any headers that the standard http.Transport adds, such as
	// User-Agent.
	func DumpRequestOut(req *http.Request, body bool) ([]byte, error) {
	save := req.Body
	dummyBody := false
	if !body \|\| req.Body == nil {
	req.Body = nil
	if req.ContentLength != 0 {
	req.Body = ioutil.NopCloser(io.LimitReader(neverEnding('x'), req.ContentLength))
	dummyBody = true
	}
	} else {
	var err error
	save, req.Body, err = drainBody(req.Body)
	if err != nil {
	return nil, err
	}
	}

	// Since we're using the actual Transport code to write the request,
	// switch to http so the Transport doesn't try to do an SSL
	// negotiation with our dumpConn and its bytes.Buffer & pipe.
	// The wire format for https and http are the same, anyway.
	reqSend := req
	if req.URL.Scheme == "https" {
	reqSend = new(http.Request)
	reqSend = req
	reqSend.URL = new(url.URL)
	reqSend.URL = req.URL
	reqSend.URL.Scheme = "http"
	}

	// Use the actual Transport code to record what we would send
	// on the wire, but not using TCP. Use a Transport with a
	// custom dialer that returns a fake net.Conn that waits
	// for the full input (and recording it), and then responds
	// with a dummy response.
	var buf bytes.Buffer // records the output
	pr, pw := io.Pipe()
	defer pr.Close()
	defer pw.Close()
	dr := &delegateReader{c: make(chan io.Reader)}

	t := &http.Transport{
	Dial: func(net, addr string) (net.Conn, error) {
	return &dumpConn{io.MultiWriter(&buf, pw), dr}, nil
	},
	}
	defer t.CloseIdleConnections()

	// Wait for the request before replying with a dummy response:
	go func() {
	req, err := http.ReadRequest(bufio.NewReader(pr))
	if err == nil {
	// Ensure all the body is read; otherwise
	// we'll get a partial dump.
	io.Copy(ioutil.Discard, req.Body)
	req.Body.Close()
	}
	dr.c <- strings.NewReader("HTTP/1.1 204 No Content\r\nConnection: close\r\n\r\n")
	}()

	_, err := t.RoundTrip(reqSend)

	req.Body = save
	if err != nil {
	return nil, err
	}
	dump := buf.Bytes()

	// If we used a dummy body above, remove it now.
	// TODO: if the req.ContentLength is large, we allocate memory
	// unnecessarily just to slice it off here. But this is just
	// a debug function, so this is acceptable for now. We could
	// discard the body earlier if this matters.
	if dummyBody {
	if i := bytes.Index(dump, []byte("\r\n\r\n")); i >= 0 {
	dump = dump[:i+4]
	}
	}
	return dump, nil
	}

	// delegateReader is a reader that delegates to another reader,
	// once it arrives on a channel.
	type delegateReader struct {
	c chan io.Reader
	r io.Reader // nil until received from c
	}

	func (r *delegateReader) Read(p []byte) (int, error) {
	if r.r == nil {
	r.r = <-r.c
	}
	return r.r.Read(p)
	}

	// Return value if nonempty, def otherwise.
	func valueOrDefault(value, def string) string {
	if value != "" {
	return value
	}
	return def
	}

	var reqWriteExcludeHeaderDump = map[string]bool{
	"Host": true, // not in Header map anyway
	"Transfer-Encoding": true,
	"Trailer": true,
	}

	// DumpRequest returns the given request in its HTTP/1.x wire
	// representation. It should only be used by servers to debug client
	// requests. The returned representation is an approximation only;
	// some details of the initial request are lost while parsing it into
	// an http.Request. In particular, the order and case of header field
	// names are lost. The order of values in multi-valued headers is kept
	// intact. HTTP/2 requests are dumped in HTTP/1.x form, not in their
	// original binary representations.
	//
	// If body is true, DumpRequest also returns the body. To do so, it
	// consumes req.Body and then replaces it with a new io.ReadCloser
	// that yields the same bytes. If DumpRequest returns an error,
	// the state of req is undefined.
	//
	// The documentation for http.Request.Write details which fields
	// of req are included in the dump.
	func DumpRequest(req *http.Request, body bool) ([]byte, error) {
	var err error
	save := req.Body
	if !body \|\| req.Body == nil {
	req.Body = nil
	} else {
	save, req.Body, err = drainBody(req.Body)
	if err != nil {
	return nil, err
	}
	}

	var b bytes.Buffer

	// By default, print out the unmodified req.RequestURI, which
	// is always set for incoming server requests. But because we
	// previously used req.URL.RequestURI and the docs weren't
	// always so clear about when to use DumpRequest vs
	// DumpRequestOut, fall back to the old way if the caller
	// provides a non-server Request.
	reqURI := req.RequestURI
	if reqURI == "" {
	reqURI = req.URL.RequestURI()
	}

	fmt.Fprintf(&b, "%s %s HTTP/%d.%d\r\n", valueOrDefault(req.Method, "GET"),
	reqURI, req.ProtoMajor, req.ProtoMinor)

	absRequestURI := strings.HasPrefix(req.RequestURI, "http://") \|\| strings.HasPrefix(req.RequestURI, "https://")
	if !absRequestURI {
	host := req.Host
	if host == "" && req.URL != nil {
	host = req.URL.Host
	}
	if host != "" {
	fmt.Fprintf(&b, "Host: %s\r\n", host)
	}
	}

	chunked := len(req.TransferEncoding) > 0 && req.TransferEncoding[0] == "chunked"
	if len(req.TransferEncoding) > 0 {
	fmt.Fprintf(&b, "Transfer-Encoding: %s\r\n", strings.Join(req.TransferEncoding, ","))
	}
	if req.Close {
	fmt.Fprintf(&b, "Connection: close\r\n")
	}

	err = req.Header.WriteSubset(&b, reqWriteExcludeHeaderDump)
	if err != nil {
	return nil, err
	}

	io.WriteString(&b, "\r\n")

	if req.Body != nil {
	var dest io.Writer = &b
	if chunked {
	dest = NewChunkedWriter(dest)
	}
	_, err = io.Copy(dest, req.Body)
	if chunked {
	dest.(io.Closer).Close()
	io.WriteString(&b, "\r\n")
	}
	}

	req.Body = save
	if err != nil {
	return nil, err
	}
	return b.Bytes(), nil
	}

	// errNoBody is a sentinel error value used by failureToReadBody so we
	// can detect that the lack of body was intentional.
	var errNoBody = errors.New("sentinel error value")

	// failureToReadBody is a io.ReadCloser that just returns errNoBody on
	// Read. It's swapped in when we don't actually want to consume
	// the body, but need a non-nil one, and want to distinguish the
	// error from reading the dummy body.
	type failureToReadBody struct{}

	func (failureToReadBody) Read([]byte) (int, error) { return 0, errNoBody }
	func (failureToReadBody) Close() error { return nil }

	// emptyBody is an instance of empty reader.
	var emptyBody = ioutil.NopCloser(strings.NewReader(""))

	// DumpResponse is like DumpRequest but dumps a response.
	func DumpResponse(resp *http.Response, body bool) ([]byte, error) {
	var b bytes.Buffer
	var err error
	save := resp.Body
	savecl := resp.ContentLength

	if !body {
	// For content length of zero. Make sure the body is an empty
	// reader, instead of returning error through failureToReadBody{}.
	if resp.ContentLength == 0 {
	resp.Body = emptyBody
	} else {
	resp.Body = failureToReadBody{}
	}
	} else if resp.Body == nil {
	resp.Body = emptyBody
	} else {
	save, resp.Body, err = drainBody(resp.Body)
	if err != nil {
	return nil, err
	}
	}
	err = resp.Write(&b)
	if err == errNoBody {
	err = nil
	}
	resp.Body = save
	resp.ContentLength = savecl
	if err != nil {
	return nil, err
	}
	return b.Bytes(), nil
	}