net/http: configurable error message for Client sent an HTTP request to an HTTPS server.

Author: bddjr

src/crypto/tls/common.go

@@ -785,6 +785,10 @@ type Config struct {
 	// autoSessionTicketKeys is like sessionTicketKeys but is owned by the
 	// auto-rotation logic. See Config.ticketKeys.
 	autoSessionTicketKeys []ticketKey
+
+	// If tlsRecordHeaderLooksLikeHTTP, call this function,
+	// then get return string to io.WriteString
+	LooksLikeHttpResponseHandler func(RecondBytes []byte) string
 }
 
 const (

src/crypto/tls/conn.go

@@ -568,6 +568,9 @@ type RecordHeaderError struct {
 	// RecordHeader contains the five bytes of TLS record header that
 	// triggered the error.
 	RecordHeader [5]byte
+	// RecondBytes contains all the bytes of the TLS record header that
+	// triggered the error.
+	RecondBytes []byte
 	// Conn provides the underlying net.Conn in the case that a client
 	// sent an initial handshake that didn't look like TLS.
 	// It is nil if there's already been a handshake or a TLS alert has
@@ -580,7 +583,8 @@ func (e RecordHeaderError) Error() string { return "tls: " + e.Msg }
 func (c *Conn) newRecordHeaderError(conn net.Conn, msg string) (err RecordHeaderError) {
 	err.Msg = msg
 	err.Conn = conn
-	copy(err.RecordHeader[:], c.rawInput.Bytes())
+	err.RecondBytes = c.rawInput.Bytes()
+	copy(err.RecordHeader[:], err.RecondBytes)
 	return err
 }
 

src/net/http/server.go

@@ -1923,7 +1923,12 @@ func (c *conn) serve(ctx context.Context) {
 			// TLS, assume they're speaking plaintext HTTP and write a
 			// 400 response on the TLS conn's underlying net.Conn.
 			if re, ok := err.(tls.RecordHeaderError); ok && re.Conn != nil && tlsRecordHeaderLooksLikeHTTP(re.RecordHeader) {
-				io.WriteString(re.Conn, "HTTP/1.0 400 Bad Request\r\n\r\nClient sent an HTTP request to an HTTPS server.\n")
+				if handler := c.server.TLSConfig.LooksLikeHttpResponseHandler; handler != nil {
+					// configurable error message for Client sent an HTTP request to an HTTPS server.
+					io.WriteString(re.Conn, handler(re.RecondBytes))
+				} else {
+					io.WriteString(re.Conn, "HTTP/1.0 400 Bad Request\r\n\r\nClient sent an HTTP request to an HTTPS server.\n")
+				}
 				re.Conn.Close()
 				return
 			}