Use splitHostPort function from net/url

client.go

@@ -50,7 +50,8 @@ type Request struct {
 
 // Hostname returns the request host without the port.
 func (r *Request) Hostname() string {
-	return hostname(r.Host)
+	host, _ := splitHostPort(r.Host)
+	return host
 }
 
 // NewRequest returns a new request. The host is inferred from the provided URL.
@@ -300,12 +301,3 @@ func validCertificate(cert *x509.Certificate) bool {
 	// No need to check hash algorithms, hopefully tls has checked for us already
 	return true
 }
-
-// hostname extracts the host name from a valid host or host:port
-func hostname(host string) string {
-	i := strings.LastIndexByte(host, ':')
-	if i != -1 {
-		return host[:i]
-	}
-	return host
-}

verify.go

@@ -1,6 +1,8 @@
 // Hostname verification code from the crypto/x509 package.
 // Modified to allow Common Names in the short term, until new certificates
 // can be issued with SANs.
+//
+// Also includes the splitHostPort function from net/url package.
 
 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -225,3 +227,38 @@ func verifyHostname(c *x509.Certificate, h string) error {
 
 	return x509.HostnameError{c, h}
 }
+
+// validOptionalPort reports whether port is either an empty string
+// or matches /^:\d*$/
+func validOptionalPort(port string) bool {
+	if port == "" {
+		return true
+	}
+	if port[0] != ':' {
+		return false
+	}
+	for _, b := range port[1:] {
+		if b < '0' || b > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+// splitHostPort separates host and port. If the port is not valid, it returns
+// the entire input as host, and it doesn't check the validity of the host.
+// Unlike net.SplitHostPort, but per RFC 3986, it requires ports to be numeric.
+func splitHostPort(hostport string) (host, port string) {
+	host = hostport
+
+	colon := strings.LastIndexByte(host, ':')
+	if colon != -1 && validOptionalPort(host[colon:]) {
+		host, port = host[:colon], host[colon+1:]
+	}
+
+	if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") {
+		host = host[1 : len(host)-1]
+	}
+
+	return
+}