remove hop-by-hop headers

pkg/filters/proxy/pool.go

@@ -22,6 +22,7 @@ import (
  "fmt"
  "io"
  "net/http"
+ "net/textproto"
  "strings"
  "sync"
  "sync/atomic"
@@ -76,6 +77,55 @@ type serverPoolContext struct {
  stdResp *http.Response
 }
 
+// Hop-by-hop headers. These are removed when sent to the backend.
+// As of RFC 7230, hop-by-hop headers are required to appear in the
+// Connection header field. These are the headers defined by the
+// obsoleted RFC 2616 (section 13.5.1) and are used for backward
+// compatibility.
+var hopHeaders = []string{
+ "Connection",
+ "Proxy-Connection", // non-standard but still sent by libcurl and rejected by e.g. google
+ "Keep-Alive",
+ "Proxy-Authenticate",
+ "Proxy-Authorization",
+ "Te", // canonicalized version of "TE"
+ "Trailer", // not Trailers per URL above; https://www.rfc-editor.org/errata_search.php?eid=4522
+ "Transfer-Encoding",
+ "Upgrade",
+}
+
+func cloneHeader(in http.Header) http.Header {
+ out := in.Clone()
+
+ // removeConnectionHeaders removes hop-by-hop headers listed in the
+ // "Connection" header of h. See RFC 7230, section 6.1
+ for _, f := range out["Connection"] {
+ for _, sf := range strings.Split(f, ",") {
+ if sf = textproto.TrimString(sf); sf != "" {
+ out.Del(sf)
+ }
+ }
+ }
+
+ for _, h := range hopHeaders {
+ out.Del(h)
+ }
+
+ // TODO: trailer support
+ //
+ // Few HTTP clients, servers, or proxies support HTTP trailers.
+ // It seems we need to do more than below to support it.
+ /*
+ // tell backend applications that care about trailer support
+ // that we support trailers.
+ if httpguts.HeaderValuesContainsToken(in["Te"], "trailers") {
+ out.Set("Te", "trailers")
+ }
+ */
+
+ return out
+}
+
 func (spCtx *serverPoolContext) prepareRequest(svr *Server, ctx stdcontext.Context, mirror bool) error {
  req := spCtx.req
 
@@ -96,7 +146,7 @@ func (spCtx *serverPoolContext) prepareRequest(svr *Server, ctx stdcontext.Conte
  return err
  }
 
- stdr.Header = spCtx.req.HTTPHeader().Clone()
+ stdr.Header = cloneHeader(req.HTTPHeader())
 
  // only set host when server address is not host name OR
  // server is explicitly told to keep the host of the request.