Function ValueFromIncomingContext

metadata/metadata.go:216–234

ValueFromIncomingContext returns the metadata value corresponding to the metadata key from the incoming metadata if it exists. Keys are matched in a case insensitive manner.

(ctx context.Context, key string)

// key from the incoming metadata if it exists. Keys are matched in a case insensitive
// manner.
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 {
		// Case insensitive comparison: MD is a map, and there's no guarantee
		// that the MD attached to the context is created using our helper
		// functions.
		if strings.EqualFold(k, key) {
			return copyOf(v)
		}
	}
	return nil
}

func copyOf(v []string) []string {
	vals := make([]string, len(v))