support h2c

client.go

@@ -950,6 +950,18 @@ func (c *Client) DisableForceHttpVersion() *Client {
 	return c
 }
 
+// EnableH2C enables HTTP/2 over TCP without TLS.
+func (c *Client) EnableH2C() *Client {
+	c.t.EnableH2C()
+	return c
+}
+
+// DisableH2C disables HTTP/2 over TCP without TLS.
+func (c *Client) DisableH2C() *Client {
+	c.t.DisableH2C()
+	return c
+}
+
 // DisableAllowGetMethodPayload disable sending GET method requests with body.
 func (c *Client) DisableAllowGetMethodPayload() *Client {
 	c.AllowGetMethodPayload = false

client_wrapper.go

@@ -520,6 +520,18 @@ func DisableForceHttpVersion() *Client {
 	return defaultClient.DisableForceHttpVersion()
 }
 
+// EnableH2C is a global wrapper methods which delegated
+// to the default client's EnableH2C.
+func EnableH2C() *Client {
+	return defaultClient.EnableH2C()
+}
+
+// DisableH2C is a global wrapper methods which delegated
+// to the default client's DisableH2C.
+func DisableH2C() *Client {
+	return defaultClient.DisableH2C()
+}
+
 // DisableAllowGetMethodPayload is a global wrapper methods which delegated
 // to the default client's DisableAllowGetMethodPayload.
 func DisableAllowGetMethodPayload() *Client {

internal/transport/option.go

@@ -70,6 +70,9 @@ type Options struct {
 	// uncompressed.
 	DisableCompression bool
 
+	// EnableH2C, if true, enables http2 over plain http without tls.
+	EnableH2C bool
+
 	// MaxIdleConns controls the maximum number of idle (keep-alive)
 	// connections across all hosts. Zero means no limit.
 	MaxIdleConns int

transport.go

@@ -363,6 +363,24 @@ func (t *Transport) EnableForceHTTP2() *Transport {
 	return t
 }
 
+// EnableH2C enables HTTP2 over TCP without TLS.
+func (t *Transport) EnableH2C() *Transport {
+	t.Options.EnableH2C = true
+	t.t2.AllowHTTP = true
+	t.t2.DialTLS = func(network, addr string, cfg *tls.Config) (net.Conn, error) {
+		return net.Dial(network, addr)
+	}
+	return t
+}
+
+// DisableH2C disables HTTP2 over TCP without TLS.
+func (t *Transport) DisableH2C() *Transport {
+	t.Options.EnableH2C = false
+	t.t2.AllowHTTP = false
+	t.t2.DialTLS = nil
+	return t
+}
+
 // EnableForceHTTP3 enable force using HTTP3 for https requests
 // (disabled by default).
 func (t *Transport) EnableForceHTTP3() *Transport {
@@ -717,8 +735,13 @@ func (t *Transport) roundTrip(req *http.Request) (resp *http.Response, err error
 		}
 	}
 
-	if t.forceHttpVersion == h3 {
-		return t.t3.RoundTrip(req)
+	if t.forceHttpVersion != "" {
+		switch t.forceHttpVersion {
+		case h3:
+			return t.t3.RoundTrip(req)
+		case h2:
+			return t.t2.RoundTrip(req)
+		}
 	}
 
 	origReq := req