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dump.go
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dump.go
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package httpdump
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/http/httputil"
"strings"
)
// Copy from net/http/httputil/dump.go.
// Remove "Trailer" from |reqWriteExcludeHeaderDump| so that Trailer header is
// set in dumped byte array. For some unknown reason, this Trailer header
// determines if Trailer is properly populated in req.Trailer.
// TODO (khe): use standard http client in replicate_client.
// 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
}
// 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,
}
// 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 = httputil.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
}