diff --git a/vendor/golang.org/x/net/http2/errors.go b/vendor/golang.org/x/net/http2/errors.go
new file mode 100644
index 0000000..71f2c46
--- /dev/null
+++ b/vendor/golang.org/x/net/http2/errors.go
@@ -0,0 +1,133 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package http2
+
+import (
+	"errors"
+	"fmt"
+)
+
+// An ErrCode is an unsigned 32-bit error code as defined in the HTTP/2 spec.
+type ErrCode uint32
+
+const (
+	ErrCodeNo                 ErrCode = 0x0
+	ErrCodeProtocol           ErrCode = 0x1
+	ErrCodeInternal           ErrCode = 0x2
+	ErrCodeFlowControl        ErrCode = 0x3
+	ErrCodeSettingsTimeout    ErrCode = 0x4
+	ErrCodeStreamClosed       ErrCode = 0x5
+	ErrCodeFrameSize          ErrCode = 0x6
+	ErrCodeRefusedStream      ErrCode = 0x7
+	ErrCodeCancel             ErrCode = 0x8
+	ErrCodeCompression        ErrCode = 0x9
+	ErrCodeConnect            ErrCode = 0xa
+	ErrCodeEnhanceYourCalm    ErrCode = 0xb
+	ErrCodeInadequateSecurity ErrCode = 0xc
+	ErrCodeHTTP11Required     ErrCode = 0xd
+)
+
+var errCodeName = map[ErrCode]string{
+	ErrCodeNo:                 "NO_ERROR",
+	ErrCodeProtocol:           "PROTOCOL_ERROR",
+	ErrCodeInternal:           "INTERNAL_ERROR",
+	ErrCodeFlowControl:        "FLOW_CONTROL_ERROR",
+	ErrCodeSettingsTimeout:    "SETTINGS_TIMEOUT",
+	ErrCodeStreamClosed:       "STREAM_CLOSED",
+	ErrCodeFrameSize:          "FRAME_SIZE_ERROR",
+	ErrCodeRefusedStream:      "REFUSED_STREAM",
+	ErrCodeCancel:             "CANCEL",
+	ErrCodeCompression:        "COMPRESSION_ERROR",
+	ErrCodeConnect:            "CONNECT_ERROR",
+	ErrCodeEnhanceYourCalm:    "ENHANCE_YOUR_CALM",
+	ErrCodeInadequateSecurity: "INADEQUATE_SECURITY",
+	ErrCodeHTTP11Required:     "HTTP_1_1_REQUIRED",
+}
+
+func (e ErrCode) String() string {
+	if s, ok := errCodeName[e]; ok {
+		return s
+	}
+	return fmt.Sprintf("unknown error code 0x%x", uint32(e))
+}
+
+// ConnectionError is an error that results in the termination of the
+// entire connection.
+type ConnectionError ErrCode
+
+func (e ConnectionError) Error() string { return fmt.Sprintf("connection error: %s", ErrCode(e)) }
+
+// StreamError is an error that only affects one stream within an
+// HTTP/2 connection.
+type StreamError struct {
+	StreamID uint32
+	Code     ErrCode
+	Cause    error // optional additional detail
+}
+
+func streamError(id uint32, code ErrCode) StreamError {
+	return StreamError{StreamID: id, Code: code}
+}
+
+func (e StreamError) Error() string {
+	if e.Cause != nil {
+		return fmt.Sprintf("stream error: stream ID %d; %v; %v", e.StreamID, e.Code, e.Cause)
+	}
+	return fmt.Sprintf("stream error: stream ID %d; %v", e.StreamID, e.Code)
+}
+
+// 6.9.1 The Flow Control Window
+// "If a sender receives a WINDOW_UPDATE that causes a flow control
+// window to exceed this maximum it MUST terminate either the stream
+// or the connection, as appropriate. For streams, [...]; for the
+// connection, a GOAWAY frame with a FLOW_CONTROL_ERROR code."
+type goAwayFlowError struct{}
+
+func (goAwayFlowError) Error() string { return "connection exceeded flow control window size" }
+
+// connError represents an HTTP/2 ConnectionError error code, along
+// with a string (for debugging) explaining why.
+//
+// Errors of this type are only returned by the frame parser functions
+// and converted into ConnectionError(Code), after stashing away
+// the Reason into the Framer's errDetail field, accessible via
+// the (*Framer).ErrorDetail method.
+type connError struct {
+	Code   ErrCode // the ConnectionError error code
+	Reason string  // additional reason
+}
+
+func (e connError) Error() string {
+	return fmt.Sprintf("http2: connection error: %v: %v", e.Code, e.Reason)
+}
+
+type pseudoHeaderError string
+
+func (e pseudoHeaderError) Error() string {
+	return fmt.Sprintf("invalid pseudo-header %q", string(e))
+}
+
+type duplicatePseudoHeaderError string
+
+func (e duplicatePseudoHeaderError) Error() string {
+	return fmt.Sprintf("duplicate pseudo-header %q", string(e))
+}
+
+type headerFieldNameError string
+
+func (e headerFieldNameError) Error() string {
+	return fmt.Sprintf("invalid header field name %q", string(e))
+}
+
+type headerFieldValueError string
+
+func (e headerFieldValueError) Error() string {
+	return fmt.Sprintf("invalid header field value %q", string(e))
+}
+
+var (
+	errMixPseudoHeaderTypes = errors.New("mix of request and response pseudo headers")
+	errPseudoAfterRegular   = errors.New("pseudo header field after regular")
+)