http3: only use :protocol pseudo-header for Extended CONNECT (#4261)

* Fix protocol

The default value should be "HTTP/3.0".

* Reject normal request with :protocol header

The :protocol pseudo header is only defined for
Extended Connect requests (RFC 9220).

* save one branch check

* Fix review issue

http3/headers.go

@@ -126,9 +126,14 @@ func requestFromHeaders(headerFields []qpack.HeaderField) (*http.Request, error)
  return nil, errors.New(":path, :authority and :method must not be empty")
  }
 
+ if !isExtendedConnected && len(hdr.Protocol) > 0 {
+ return nil, errors.New(":protocol must be empty")
+ }
+
  var u *url.URL
  var requestURI string
- var protocol string
+
+ protocol := "HTTP/3.0"
 
  if isConnect {
  u = &url.URL{}
@@ -137,15 +142,14 @@ func requestFromHeaders(headerFields []qpack.HeaderField) (*http.Request, error)
  if err != nil {
  return nil, err
  }
+ protocol = hdr.Protocol
  } else {
  u.Path = hdr.Path
  }
  u.Scheme = hdr.Scheme
  u.Host = hdr.Authority
  requestURI = hdr.Authority
- protocol = hdr.Protocol
  } else {
- protocol = "HTTP/3.0"
  u, err = url.ParseRequestURI(hdr.Path)
  if err != nil {
  return nil, fmt.Errorf("invalid content length: %w", err)

http3/headers_test.go

@@ -212,6 +212,17 @@ var _ = Describe("Request", func() {
  Expect(err).To(MatchError(":path, :authority and :method must not be empty"))
  })
 
+ It("errors with invalid protocol", func() {
+ headers := []qpack.HeaderField{
+ {Name: ":path", Value: "/foo"},
+ {Name: ":authority", Value: "quic.clemente.io"},
+ {Name: ":method", Value: "GET"},
+ {Name: ":protocol", Value: "connect-udp"},
+ }
+ _, err := requestFromHeaders(headers)
+ Expect(err).To(MatchError(":protocol must be empty"))
+ })
+
  Context("regular HTTP CONNECT", func() {
  It("handles CONNECT method", func() {
  headers := []qpack.HeaderField{
@@ -221,6 +232,7 @@ var _ = Describe("Request", func() {
  req, err := requestFromHeaders(headers)
  Expect(err).NotTo(HaveOccurred())
  Expect(req.Method).To(Equal(http.MethodConnect))
+ Expect(req.Proto).To(Equal("HTTP/3.0"))
  Expect(req.RequestURI).To(Equal("quic.clemente.io"))
  })