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context.go
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context.go
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package runtime
import (
"context"
"encoding/base64"
"fmt"
"net"
"net/http"
"net/textproto"
"strconv"
"strings"
"sync"
"time"
"google.golang.org/grpc/codes"
"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
)
type (
rpcMethodKey struct{}
httpPathPatternKey struct{}
AnnotateContextOption func(ctx context.Context) context.Context
)
func WithHTTPPathPattern(pattern string) AnnotateContextOption {
return func(ctx context.Context) context.Context {
return withHTTPPathPattern(ctx, pattern)
}
}
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, rpcMethodName string, options ...AnnotateContextOption) (context.Context, error) {
ctx, md, err := annotateContext(ctx, mux, req, rpcMethodName, options...)
if err != nil {
return nil, err
}
if md == nil {
return ctx, nil
}
return metadata.NewOutgoingContext(ctx, md), nil
}
// AnnotateIncomingContext adds context information such as metadata from the request.
// Attach metadata as incoming context.
func AnnotateIncomingContext(ctx context.Context, mux *ServeMux, req *http.Request, rpcMethodName string, options ...AnnotateContextOption) (context.Context, error) {
ctx, md, err := annotateContext(ctx, mux, req, rpcMethodName, options...)
if err != nil {
return nil, err
}
if md == nil {
return ctx, nil
}
return metadata.NewIncomingContext(ctx, md), nil
}
func annotateContext(ctx context.Context, mux *ServeMux, req *http.Request, rpcMethodName string, options ...AnnotateContextOption) (context.Context, metadata.MD, error) {
ctx = withRPCMethod(ctx, rpcMethodName)
for _, o := range options {
ctx = o(ctx)
}
var pairs []string
timeout := DefaultContextTimeout
if tm := req.Header.Get(metadataGrpcTimeout); tm != "" {
var err error
timeout, err = timeoutDecode(tm)
if err != nil {
return nil, nil, status.Errorf(codes.InvalidArgument, "invalid grpc-timeout: %s", tm)
}
}
for key, vals := range req.Header {
key = textproto.CanonicalMIMEHeaderKey(key)
for _, val := range vals {
// 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, 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))
}
}
}
if timeout != 0 {
//nolint:govet // The context outlives this function
ctx, _ = context.WithTimeout(ctx, timeout)
}
if len(pairs) == 0 {
return ctx, nil, nil
}
md := metadata.Pairs(pairs...)
for _, mda := range mux.metadataAnnotators {
md = metadata.Join(md, mda(ctx, req))
}
return 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
}
// ServerTransportStream implements grpc.ServerTransportStream.
// It should only be used by the generated files to support grpc.SendHeader
// outside of gRPC server use.
type ServerTransportStream struct {
mu sync.Mutex
header metadata.MD
trailer metadata.MD
}
// Method returns the method for the stream.
func (s *ServerTransportStream) Method() string {
return ""
}
// Header returns the header metadata of the stream.
func (s *ServerTransportStream) Header() metadata.MD {
s.mu.Lock()
defer s.mu.Unlock()
return s.header.Copy()
}
// SetHeader sets the header metadata.
func (s *ServerTransportStream) SetHeader(md metadata.MD) error {
if md.Len() == 0 {
return nil
}
s.mu.Lock()
s.header = metadata.Join(s.header, md)
s.mu.Unlock()
return nil
}
// SendHeader sets the header metadata.
func (s *ServerTransportStream) SendHeader(md metadata.MD) error {
return s.SetHeader(md)
}
// Trailer returns the cached trailer metadata.
func (s *ServerTransportStream) Trailer() metadata.MD {
s.mu.Lock()
defer s.mu.Unlock()
return s.trailer.Copy()
}
// SetTrailer sets the trailer metadata.
func (s *ServerTransportStream) SetTrailer(md metadata.MD) error {
if md.Len() == 0 {
return nil
}
s.mu.Lock()
s.trailer = metadata.Join(s.trailer, md)
s.mu.Unlock()
return nil
}
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
// permanent 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
}
// RPCMethod returns the method string for the server context. The returned
// string is in the format of "/package.service/method".
func RPCMethod(ctx context.Context) (string, bool) {
m := ctx.Value(rpcMethodKey{})
if m == nil {
return "", false
}
ms, ok := m.(string)
if !ok {
return "", false
}
return ms, true
}
func withRPCMethod(ctx context.Context, rpcMethodName string) context.Context {
return context.WithValue(ctx, rpcMethodKey{}, rpcMethodName)
}
// HTTPPathPattern returns the HTTP path pattern string relating to the HTTP handler, if one exists.
// The format of the returned string is defined by the google.api.http path template type.
func HTTPPathPattern(ctx context.Context) (string, bool) {
m := ctx.Value(httpPathPatternKey{})
if m == nil {
return "", false
}
ms, ok := m.(string)
if !ok {
return "", false
}
return ms, true
}
func withHTTPPathPattern(ctx context.Context, httpPathPattern string) context.Context {
return context.WithValue(ctx, httpPathPatternKey{}, httpPathPattern)
}