net/http: normalize empty port in URL.Host's ":port"

- Ensures that the empty port and preceeding ":"
in a URL.Host are stripped.
Normalize the empty port in a URL.Host's ":port" as
mandated by RFC 3986 Section 6.2.3 which states that:
`Likewise an explicit ":port", for which the port is empty or
the default for the scheme, is equivalent to one where the port
and its ":" delimiter are elided and thus should be
removed by scheme-based normalization.`

- Moves function `hasPort` from client.go (where it was defined but
not used directly), to http.go the common area.

Fixes #14836

Change-Id: I2067410377be9c71106b1717abddc2f8b1da1c03
Reviewed-on: https://go-review.googlesource.com/22140Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/http/client.go

@@ -110,10 +110,6 @@ type RoundTripper interface {
 	RoundTrip(*Request) (*Response, error)
 }
 
-// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
-// return true if the string includes a port.
-func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
-
 // refererForURL returns a referer without any authentication info or
 // an empty string if lastReq scheme is https and newReq scheme is http.
 func refererForURL(lastReq, newReq *url.URL) string {

src/net/http/http.go

@@ -4,6 +4,10 @@
 
 package http
 
+import (
+	"strings"
+)
+
 // maxInt64 is the effective "infinite" value for the Server and
 // Transport's byte-limiting readers.
 const maxInt64 = 1<<63 - 1
@@ -18,3 +22,16 @@ type contextKey struct {
 }
 
 func (k *contextKey) String() string { return "net/http context value " + k.name }
+
+// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
+// return true if the string includes a port.
+func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
+
+// removeEmptyPort strips the empty port in ":port" to ""
+// as mandated by RFC 3986 Section 6.2.3.
+func removeEmptyPort(host string) string {
+	if hasPort(host) {
+		return strings.TrimSuffix(host, ":")
+	}
+	return host
+}

src/net/http/request.go

@@ -660,6 +660,8 @@ func NewRequest(method, urlStr string, body io.Reader) (*Request, error) {
 	if !ok && body != nil {
 		rc = ioutil.NopCloser(body)
 	}
+	// The host's colon:port should be normalized. See Issue 14836.
+	u.Host = removeEmptyPort(u.Host)
 	req := &Request{
 		Method:     method,
 		URL:        u,

src/net/http/request_test.go

@@ -398,11 +398,13 @@ var newRequestHostTests = []struct {
 
 	{"http://192.168.0.1/", "192.168.0.1"},
 	{"http://192.168.0.1:8080/", "192.168.0.1:8080"},
+	{"http://192.168.0.1:/", "192.168.0.1"},
 
 	{"http://[fe80::1]/", "[fe80::1]"},
 	{"http://[fe80::1]:8080/", "[fe80::1]:8080"},
 	{"http://[fe80::1%25en0]/", "[fe80::1%en0]"},
 	{"http://[fe80::1%25en0]:8080/", "[fe80::1%en0]:8080"},
+	{"http://[fe80::1%25en0]:/", "[fe80::1%en0]"},
 }
 
 func TestNewRequestHost(t *testing.T) {