correctly read the hostname from a http.Request

h2quic/client.go

@@ -145,7 +145,7 @@ func (c *Client) Do(req *http.Request) (*http.Response, error) {
 	if req.URL.Scheme != "https" {
 		return nil, errors.New("quic http2: unsupported scheme")
 	}
-	if authorityAddr("https", req.Host) != c.hostname {
+	if authorityAddr("https", hostnameFromRequest(req)) != c.hostname {
 		utils.Debugf("%s vs %s", req.Host, c.hostname)
 		return nil, errors.New("h2quic Client BUG: Do called for the wrong client")
 	}

h2quic/request.go

@@ -68,3 +68,13 @@ func requestFromHeaders(headers []hpack.HeaderField) (*http.Request, error) {
 		TLS:           &tls.ConnectionState{},
 	}, nil
 }
+
+func hostnameFromRequest(req *http.Request) string {
+	if len(req.Host) > 0 {
+		return req.Host
+	}
+	if req.URL != nil {
+		return req.URL.Host
+	}
+	return ""
+}

h2quic/request_test.go

@@ -2,6 +2,7 @@ package h2quic
 
 import (
 	"net/http"
+	"net/url"
 
 	"golang.org/x/net/http2/hpack"
 
@@ -90,4 +91,31 @@ var _ = Describe("Request", func() {
 		_, err := requestFromHeaders(headers)
 		Expect(err).To(MatchError(":path, :authority and :method must not be empty"))
 	})
+
+	Context("extracting the hostname from a request", func() {
+		var url *url.URL
+
+		BeforeEach(func() {
+			var err error
+			url, err = url.Parse("https://quic.clemente.io:1337")
+			Expect(err).ToNot(HaveOccurred())
+		})
+
+		It("uses req.Host if available", func() {
+			req := &http.Request{
+				Host: "www.example.org",
+				URL:  url,
+			}
+			Expect(hostnameFromRequest(req)).To(Equal("www.example.org"))
+		})
+
+		It("uses req.URL.Host if req.Host is not set", func() {
+			req := &http.Request{URL: url}
+			Expect(hostnameFromRequest(req)).To(Equal("quic.clemente.io:1337"))
+		})
+
+		It("returns an empty hostname if nothing is set", func() {
+			Expect(hostnameFromRequest(&http.Request{})).To(BeEmpty())
+		})
+	})
 })