diff --git a/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/context.go b/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/context.go
new file mode 100644
index 0000000..896057e
--- /dev/null
+++ b/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/context.go
@@ -0,0 +1,210 @@
+package runtime
+
+import (
+	"context"
+	"encoding/base64"
+	"fmt"
+	"net"
+	"net/http"
+	"net/textproto"
+	"strconv"
+	"strings"
+	"time"
+
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
+)
+
+// MetadataHeaderPrefix is the http prefix that represents custom metadata
+// parameters to or from a gRPC call.
+const MetadataHeaderPrefix = "Grpc-Metadata-"
+
+// MetadataPrefix is prepended to permanent HTTP header keys (as specified
+// by the IANA) when added to the gRPC context.
+const MetadataPrefix = "grpcgateway-"
+
+// MetadataTrailerPrefix is prepended to gRPC metadata as it is converted to
+// HTTP headers in a response handled by grpc-gateway
+const MetadataTrailerPrefix = "Grpc-Trailer-"
+
+const metadataGrpcTimeout = "Grpc-Timeout"
+const metadataHeaderBinarySuffix = "-Bin"
+
+const xForwardedFor = "X-Forwarded-For"
+const xForwardedHost = "X-Forwarded-Host"
+
+var (
+	// DefaultContextTimeout is used for gRPC call context.WithTimeout whenever a Grpc-Timeout inbound
+	// header isn't present. If the value is 0 the sent `context` will not have a timeout.
+	DefaultContextTimeout = 0 * time.Second
+)
+
+func decodeBinHeader(v string) ([]byte, error) {
+	if len(v)%4 == 0 {
+		// Input was padded, or padding was not necessary.
+		return base64.StdEncoding.DecodeString(v)
+	}
+	return base64.RawStdEncoding.DecodeString(v)
+}
+
+/*
+AnnotateContext adds context information such as metadata from the request.
+
+At a minimum, the RemoteAddr is included in the fashion of "X-Forwarded-For",
+except that the forwarded destination is not another HTTP service but rather
+a gRPC service.
+*/
+func AnnotateContext(ctx context.Context, mux *ServeMux, req *http.Request) (context.Context, error) {
+	var pairs []string
+	timeout := DefaultContextTimeout
+	if tm := req.Header.Get(metadataGrpcTimeout); tm != "" {
+		var err error
+		timeout, err = timeoutDecode(tm)
+		if err != nil {
+			return nil, status.Errorf(codes.InvalidArgument, "invalid grpc-timeout: %s", tm)
+		}
+	}
+
+	for key, vals := range req.Header {
+		for _, val := range vals {
+			key = textproto.CanonicalMIMEHeaderKey(key)
+			// For backwards-compatibility, pass through 'authorization' header with no prefix.
+			if key == "Authorization" {
+				pairs = append(pairs, "authorization", val)
+			}
+			if h, ok := mux.incomingHeaderMatcher(key); ok {
+				// Handles "-bin" metadata in grpc, since grpc will do another base64
+				// encode before sending to server, we need to decode it first.
+				if strings.HasSuffix(key, metadataHeaderBinarySuffix) {
+					b, err := decodeBinHeader(val)
+					if err != nil {
+						return nil, status.Errorf(codes.InvalidArgument, "invalid binary header %s: %s", key, err)
+					}
+
+					val = string(b)
+				}
+				pairs = append(pairs, h, val)
+			}
+		}
+	}
+	if host := req.Header.Get(xForwardedHost); host != "" {
+		pairs = append(pairs, strings.ToLower(xForwardedHost), host)
+	} else if req.Host != "" {
+		pairs = append(pairs, strings.ToLower(xForwardedHost), req.Host)
+	}
+
+	if addr := req.RemoteAddr; addr != "" {
+		if remoteIP, _, err := net.SplitHostPort(addr); err == nil {
+			if fwd := req.Header.Get(xForwardedFor); fwd == "" {
+				pairs = append(pairs, strings.ToLower(xForwardedFor), remoteIP)
+			} else {
+				pairs = append(pairs, strings.ToLower(xForwardedFor), fmt.Sprintf("%s, %s", fwd, remoteIP))
+			}
+		} else {
+			grpclog.Infof("invalid remote addr: %s", addr)
+		}
+	}
+
+	if timeout != 0 {
+		ctx, _ = context.WithTimeout(ctx, timeout)
+	}
+	if len(pairs) == 0 {
+		return ctx, nil
+	}
+	md := metadata.Pairs(pairs...)
+	for _, mda := range mux.metadataAnnotators {
+		md = metadata.Join(md, mda(ctx, req))
+	}
+	return metadata.NewOutgoingContext(ctx, md), nil
+}
+
+// ServerMetadata consists of metadata sent from gRPC server.
+type ServerMetadata struct {
+	HeaderMD  metadata.MD
+	TrailerMD metadata.MD
+}
+
+type serverMetadataKey struct{}
+
+// NewServerMetadataContext creates a new context with ServerMetadata
+func NewServerMetadataContext(ctx context.Context, md ServerMetadata) context.Context {
+	return context.WithValue(ctx, serverMetadataKey{}, md)
+}
+
+// ServerMetadataFromContext returns the ServerMetadata in ctx
+func ServerMetadataFromContext(ctx context.Context) (md ServerMetadata, ok bool) {
+	md, ok = ctx.Value(serverMetadataKey{}).(ServerMetadata)
+	return
+}
+
+func timeoutDecode(s string) (time.Duration, error) {
+	size := len(s)
+	if size < 2 {
+		return 0, fmt.Errorf("timeout string is too short: %q", s)
+	}
+	d, ok := timeoutUnitToDuration(s[size-1])
+	if !ok {
+		return 0, fmt.Errorf("timeout unit is not recognized: %q", s)
+	}
+	t, err := strconv.ParseInt(s[:size-1], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	return d * time.Duration(t), nil
+}
+
+func timeoutUnitToDuration(u uint8) (d time.Duration, ok bool) {
+	switch u {
+	case 'H':
+		return time.Hour, true
+	case 'M':
+		return time.Minute, true
+	case 'S':
+		return time.Second, true
+	case 'm':
+		return time.Millisecond, true
+	case 'u':
+		return time.Microsecond, true
+	case 'n':
+		return time.Nanosecond, true
+	default:
+	}
+	return
+}
+
+// isPermanentHTTPHeader checks whether hdr belongs to the list of
+// permenant request headers maintained by IANA.
+// http://www.iana.org/assignments/message-headers/message-headers.xml
+func isPermanentHTTPHeader(hdr string) bool {
+	switch hdr {
+	case
+		"Accept",
+		"Accept-Charset",
+		"Accept-Language",
+		"Accept-Ranges",
+		"Authorization",
+		"Cache-Control",
+		"Content-Type",
+		"Cookie",
+		"Date",
+		"Expect",
+		"From",
+		"Host",
+		"If-Match",
+		"If-Modified-Since",
+		"If-None-Match",
+		"If-Schedule-Tag-Match",
+		"If-Unmodified-Since",
+		"Max-Forwards",
+		"Origin",
+		"Pragma",
+		"Referer",
+		"User-Agent",
+		"Via",
+		"Warning":
+		return true
+	}
+	return false
+}