gtsocial-umbx

metadata.go (8558B)

---

 /*
  *
  * Copyright 2014 gRPC authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  */
 
 // Package metadata define the structure of the metadata supported by gRPC library.
 // Please refer to https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md
 // for more information about custom-metadata.
 package metadata // import "google.golang.org/grpc/metadata"
 
 import (
 	"context"
 	"fmt"
 	"strings"
 )
 
 // DecodeKeyValue returns k, v, nil.
 //
 // Deprecated: use k and v directly instead.
 func DecodeKeyValue(k, v string) (string, string, error) {
 	return k, v, nil
 }
 
 // MD is a mapping from metadata keys to values. Users should use the following
 // two convenience functions New and Pairs to generate MD.
 type MD map[string][]string
 
 // New creates an MD from a given key-value map.
 //
 // Only the following ASCII characters are allowed in keys:
 //   - digits: 0-9
 //   - uppercase letters: A-Z (normalized to lower)
 //   - lowercase letters: a-z
 //   - special characters: -_.
 //
 // Uppercase letters are automatically converted to lowercase.
 //
 // Keys beginning with "grpc-" are reserved for grpc-internal use only and may
 // result in errors if set in metadata.
 func New(m map[string]string) MD {
 	md := make(MD, len(m))
 	for k, val := range m {
 		key := strings.ToLower(k)
 		md[key] = append(md[key], val)
 	}
 	return md
 }
 
 // Pairs returns an MD formed by the mapping of key, value ...
 // Pairs panics if len(kv) is odd.
 //
 // Only the following ASCII characters are allowed in keys:
 //   - digits: 0-9
 //   - uppercase letters: A-Z (normalized to lower)
 //   - lowercase letters: a-z
 //   - special characters: -_.
 //
 // Uppercase letters are automatically converted to lowercase.
 //
 // Keys beginning with "grpc-" are reserved for grpc-internal use only and may
 // result in errors if set in metadata.
 func Pairs(kv ...string) MD {
 	if len(kv)%2 == 1 {
 		panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
 	}
 	md := make(MD, len(kv)/2)
 	for i := 0; i < len(kv); i += 2 {
 		key := strings.ToLower(kv[i])
 		md[key] = append(md[key], kv[i+1])
 	}
 	return md
 }
 
 // Len returns the number of items in md.
 func (md MD) Len() int {
 	return len(md)
 }
 
 // Copy returns a copy of md.
 func (md MD) Copy() MD {
 	out := make(MD, len(md))
 	for k, v := range md {
 		out[k] = copyOf(v)
 	}
 	return out
 }
 
 // Get obtains the values for a given key.
 //
 // k is converted to lowercase before searching in md.
 func (md MD) Get(k string) []string {
 	k = strings.ToLower(k)
 	return md[k]
 }
 
 // Set sets the value of a given key with a slice of values.
 //
 // k is converted to lowercase before storing in md.
 func (md MD) Set(k string, vals ...string) {
 	if len(vals) == 0 {
 		return
 	}
 	k = strings.ToLower(k)
 	md[k] = vals
 }
 
 // Append adds the values to key k, not overwriting what was already stored at
 // that key.
 //
 // k is converted to lowercase before storing in md.
 func (md MD) Append(k string, vals ...string) {
 	if len(vals) == 0 {
 		return
 	}
 	k = strings.ToLower(k)
 	md[k] = append(md[k], vals...)
 }
 
 // Delete removes the values for a given key k which is converted to lowercase
 // before removing it from md.
 func (md MD) Delete(k string) {
 	k = strings.ToLower(k)
 	delete(md, k)
 }
 
 // Join joins any number of mds into a single MD.
 //
 // The order of values for each key is determined by the order in which the mds
 // containing those values are presented to Join.
 func Join(mds ...MD) MD {
 	out := MD{}
 	for _, md := range mds {
 		for k, v := range md {
 			out[k] = append(out[k], v...)
 		}
 	}
 	return out
 }
 
 type mdIncomingKey struct{}
 type mdOutgoingKey struct{}
 
 // NewIncomingContext creates a new context with incoming md attached.
 func NewIncomingContext(ctx context.Context, md MD) context.Context {
 	return context.WithValue(ctx, mdIncomingKey{}, md)
 }
 
 // NewOutgoingContext creates a new context with outgoing md attached. If used
 // in conjunction with AppendToOutgoingContext, NewOutgoingContext will
 // overwrite any previously-appended metadata.
 func NewOutgoingContext(ctx context.Context, md MD) context.Context {
 	return context.WithValue(ctx, mdOutgoingKey{}, rawMD{md: md})
 }
 
 // AppendToOutgoingContext returns a new context with the provided kv merged
 // with any existing metadata in the context. Please refer to the documentation
 // of Pairs for a description of kv.
 func AppendToOutgoingContext(ctx context.Context, kv ...string) context.Context {
 	if len(kv)%2 == 1 {
 		panic(fmt.Sprintf("metadata: AppendToOutgoingContext got an odd number of input pairs for metadata: %d", len(kv)))
 	}
 	md, _ := ctx.Value(mdOutgoingKey{}).(rawMD)
 	added := make([][]string, len(md.added)+1)
 	copy(added, md.added)
 	kvCopy := make([]string, 0, len(kv))
 	for i := 0; i < len(kv); i += 2 {
 		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
 	}
 	added[len(added)-1] = kvCopy
 	return context.WithValue(ctx, mdOutgoingKey{}, rawMD{md: md.md, added: added})
 }
 
 // FromIncomingContext returns the incoming metadata in ctx if it exists.
 //
 // All keys in the returned MD are lowercase.
 func FromIncomingContext(ctx context.Context) (MD, bool) {
 	md, ok := ctx.Value(mdIncomingKey{}).(MD)
 	if !ok {
 		return nil, false
 	}
 	out := make(MD, len(md))
 	for k, v := range md {
 		// We need to manually convert all keys to lower case, because MD is a
 		// map, and there's no guarantee that the MD attached to the context is
 		// created using our helper functions.
 		key := strings.ToLower(k)
 		out[key] = copyOf(v)
 	}
 	return out, true
 }
 
 // ValueFromIncomingContext returns the metadata value corresponding to the metadata
 // key from the incoming metadata if it exists. Key must be lower-case.
 //
 // # Experimental
 //
 // Notice: This API is EXPERIMENTAL and may be changed or removed in a
 // later release.
 func ValueFromIncomingContext(ctx context.Context, key string) []string {
 	md, ok := ctx.Value(mdIncomingKey{}).(MD)
 	if !ok {
 		return nil
 	}
 
 	if v, ok := md[key]; ok {
 		return copyOf(v)
 	}
 	for k, v := range md {
 		// We need to manually convert all keys to lower case, because MD is a
 		// map, and there's no guarantee that the MD attached to the context is
 		// created using our helper functions.
 		if strings.ToLower(k) == key {
 			return copyOf(v)
 		}
 	}
 	return nil
 }
 
 // the returned slice must not be modified in place
 func copyOf(v []string) []string {
 	vals := make([]string, len(v))
 	copy(vals, v)
 	return vals
 }
 
 // FromOutgoingContextRaw returns the un-merged, intermediary contents of rawMD.
 //
 // Remember to perform strings.ToLower on the keys, for both the returned MD (MD
 // is a map, there's no guarantee it's created using our helper functions) and
 // the extra kv pairs (AppendToOutgoingContext doesn't turn them into
 // lowercase).
 //
 // This is intended for gRPC-internal use ONLY. Users should use
 // FromOutgoingContext instead.
 func FromOutgoingContextRaw(ctx context.Context) (MD, [][]string, bool) {
 	raw, ok := ctx.Value(mdOutgoingKey{}).(rawMD)
 	if !ok {
 		return nil, nil, false
 	}
 
 	return raw.md, raw.added, true
 }
 
 // FromOutgoingContext returns the outgoing metadata in ctx if it exists.
 //
 // All keys in the returned MD are lowercase.
 func FromOutgoingContext(ctx context.Context) (MD, bool) {
 	raw, ok := ctx.Value(mdOutgoingKey{}).(rawMD)
 	if !ok {
 		return nil, false
 	}
 
 	mdSize := len(raw.md)
 	for i := range raw.added {
 		mdSize += len(raw.added[i]) / 2
 	}
 
 	out := make(MD, mdSize)
 	for k, v := range raw.md {
 		// We need to manually convert all keys to lower case, because MD is a
 		// map, and there's no guarantee that the MD attached to the context is
 		// created using our helper functions.
 		key := strings.ToLower(k)
 		out[key] = copyOf(v)
 	}
 	for _, added := range raw.added {
 		if len(added)%2 == 1 {
 			panic(fmt.Sprintf("metadata: FromOutgoingContext got an odd number of input pairs for metadata: %d", len(added)))
 		}
 
 		for i := 0; i < len(added); i += 2 {
 			key := strings.ToLower(added[i])
 			out[key] = append(out[key], added[i+1])
 		}
 	}
 	return out, ok
 }
 
 type rawMD struct {
 	md    MD
 	added [][]string
 }