rbd: add aws-sts-metdata encryption type

With Amazon STS and kubernetes cluster is configured with
OIDC identity provider, credentials to access Amazon KMS
can be fetched using oidc-token(serviceaccount token).
Each tenant/namespace needs to create a secret with aws region,
role and CMK ARN.
Ceph-CSI will assume the given role with oidc token and access
aws KMS, with given CMK to encrypt/decrypt DEK which will stored
in the image metdata.

Refer: https://docs.aws.amazon.com/STS/latest/APIReference/welcome.html
Resolves: #2879

Signed-off-by: Rakshith R <rar@redhat.com>

vendor/github.com/aws/smithy-go/middleware/doc.go

@@ -0,0 +1,67 @@
+// Package middleware provides transport agnostic middleware for decorating SDK
+// handlers.
+//
+// The Smithy middleware stack provides ordered behavior to be invoked on an
+// underlying handler. The stack is separated into steps that are invoked in a
+// static order. A step is a collection of middleware that are injected into a
+// ordered list defined by the user. The user may add, insert, swap, and remove a
+// step's middleware. When the stack is invoked the step middleware become static,
+// and their order cannot be modified.
+//
+// A stack and its step middleware are **not** safe to modify concurrently.
+//
+// A stack will use the ordered list of middleware to decorate a underlying
+// handler. A handler could be something like an HTTP Client that round trips an
+// API operation over HTTP.
+//
+// Smithy Middleware Stack
+//
+// A Stack is a collection of middleware that wrap a handler. The stack can be
+// broken down into discreet steps. Each step may contain zero or more middleware
+// specific to that stack's step.
+//
+// A Stack Step is a predefined set of middleware that are invoked in a static
+// order by the Stack. These steps represent fixed points in the middleware stack
+// for organizing specific behavior, such as serialize and build. A Stack Step is
+// composed of zero or more middleware that are specific to that step. A step may
+// define its own set of input/output parameters the generic input/output
+// parameters are cast from. A step calls its middleware recursively, before
+// calling the next step in the stack returning the result or error of the step
+// middleware decorating the underlying handler.
+//
+// * Initialize: Prepares the input, and sets any default parameters as needed,
+// (e.g. idempotency token, and presigned URLs).
+//
+// * Serialize: Serializes the prepared input into a data structure that can be
+// consumed by the target transport's message, (e.g. REST-JSON serialization).
+//
+// * Build: Adds additional metadata to the serialized transport message, (e.g.
+// HTTP's Content-Length header, or body checksum). Decorations and
+// modifications to the message should be copied to all message attempts.
+//
+// * Finalize: Performs final preparations needed before sending the message. The
+// message should already be complete by this stage, and is only alternated to
+// meet the expectations of the recipient, (e.g. Retry and AWS SigV4 request
+// signing).
+//
+// * Deserialize: Reacts to the handler's response returned by the recipient of
+// the request message. Deserializes the response into a structured type or
+// error above stacks can react to.
+//
+// Adding Middleware to a Stack Step
+//
+// Middleware can be added to a step front or back, or relative, by name, to an
+// existing middleware in that stack. If a middleware does not have a name, a
+// unique name will be generated at the middleware and be added to the step.
+//
+//     // Create middleware stack
+//     stack := middleware.NewStack()
+//
+//     // Add middleware to stack steps
+//     stack.Initialize.Add(paramValidationMiddleware, middleware.After)
+//     stack.Serialize.Add(marshalOperationFoo, middleware.After)
+//     stack.Deserialize.Add(unmarshalOperationFoo, middleware.After)
+//
+//     // Invoke middleware on handler.
+//     resp, err := stack.HandleMiddleware(ctx, req.Input, clientHandler)
+package middleware

vendor/github.com/aws/smithy-go/middleware/logging.go

@@ -0,0 +1,46 @@
+package middleware
+
+import (
+	"context"
+
+	"github.com/aws/smithy-go/logging"
+)
+
+// loggerKey is the context value key for which the logger is associated with.
+type loggerKey struct{}
+
+// GetLogger takes a context to retrieve a Logger from. If no logger is present on the context a logging.Nop logger
+// is returned. If the logger retrieved from context supports the ContextLogger interface, the context will be passed
+// to the WithContext method and the resulting logger will be returned. Otherwise the stored logger is returned as is.
+func GetLogger(ctx context.Context) logging.Logger {
+	logger, ok := ctx.Value(loggerKey{}).(logging.Logger)
+	if !ok || logger == nil {
+		return logging.Nop{}
+	}
+
+	return logging.WithContext(ctx, logger)
+}
+
+// SetLogger sets the provided logger value on the provided ctx.
+func SetLogger(ctx context.Context, logger logging.Logger) context.Context {
+	return context.WithValue(ctx, loggerKey{}, logger)
+}
+
+type setLogger struct {
+	Logger logging.Logger
+}
+
+// AddSetLoggerMiddleware adds a middleware that will add the provided logger to the middleware context.
+func AddSetLoggerMiddleware(stack *Stack, logger logging.Logger) error {
+	return stack.Initialize.Add(&setLogger{Logger: logger}, After)
+}
+
+func (a *setLogger) ID() string {
+	return "SetLogger"
+}
+
+func (a *setLogger) HandleInitialize(ctx context.Context, in InitializeInput, next InitializeHandler) (
+	out InitializeOutput, metadata Metadata, err error,
+) {
+	return next.HandleInitialize(SetLogger(ctx, a.Logger), in)
+}

vendor/github.com/aws/smithy-go/middleware/metadata.go

@@ -0,0 +1,65 @@
+package middleware
+
+// MetadataReader provides an interface for reading metadata from the
+// underlying metadata container.
+type MetadataReader interface {
+	Get(key interface{}) interface{}
+}
+
+// Metadata provides storing and reading metadata values. Keys may be any
+// comparable value type. Get and set will panic if key is not a comparable
+// value type.
+//
+// Metadata uses lazy initialization, and Set method must be called as an
+// addressable value, or pointer. Not doing so may cause key/value pair to not
+// be set.
+type Metadata struct {
+	values map[interface{}]interface{}
+}
+
+// Get attempts to retrieve the value the key points to. Returns nil if the
+// key was not found.
+//
+// Panics if key type is not comparable.
+func (m Metadata) Get(key interface{}) interface{} {
+	return m.values[key]
+}
+
+// Clone creates a shallow copy of Metadata entries, returning a new Metadata
+// value with the original entries copied into it.
+func (m Metadata) Clone() Metadata {
+	vs := make(map[interface{}]interface{}, len(m.values))
+	for k, v := range m.values {
+		vs[k] = v
+	}
+
+	return Metadata{
+		values: vs,
+	}
+}
+
+// Set stores the value pointed to by the key. If a value already exists at
+// that key it will be replaced with the new value.
+//
+// Set method must be called as an addressable value, or pointer. If Set is not
+// called as an addressable value or pointer, the key value pair being set may
+// be lost.
+//
+// Panics if the key type is not comparable.
+func (m *Metadata) Set(key, value interface{}) {
+	if m.values == nil {
+		m.values = map[interface{}]interface{}{}
+	}
+	m.values[key] = value
+}
+
+// Has returns whether the key exists in the metadata.
+//
+// Panics if the key type is not comparable.
+func (m Metadata) Has(key interface{}) bool {
+	if m.values == nil {
+		return false
+	}
+	_, ok := m.values[key]
+	return ok
+}

vendor/github.com/aws/smithy-go/middleware/middleware.go

@@ -0,0 +1,71 @@
+package middleware
+
+import (
+	"context"
+)
+
+// Handler provides the interface for performing the logic to obtain an output,
+// or error for the given input.
+type Handler interface {
+	// Handle performs logic to obtain an output for the given input. Handler
+	// should be decorated with middleware to perform input specific behavior.
+	Handle(ctx context.Context, input interface{}) (
+		output interface{}, metadata Metadata, err error,
+	)
+}
+
+// HandlerFunc provides a wrapper around a function pointer to be used as a
+// middleware handler.
+type HandlerFunc func(ctx context.Context, input interface{}) (
+	output interface{}, metadata Metadata, err error,
+)
+
+// Handle invokes the underlying function, returning the result.
+func (fn HandlerFunc) Handle(ctx context.Context, input interface{}) (
+	output interface{}, metadata Metadata, err error,
+) {
+	return fn(ctx, input)
+}
+
+// Middleware provides the interface to call handlers in a chain.
+type Middleware interface {
+	// ID provides a unique identifier for the middleware.
+	ID() string
+
+	// Performs the middleware's handling of the input, returning the output,
+	// or error. The middleware can invoke the next Handler if handling should
+	// continue.
+	HandleMiddleware(ctx context.Context, input interface{}, next Handler) (
+		output interface{}, metadata Metadata, err error,
+	)
+}
+
+// decoratedHandler wraps a middleware in order to to call the next handler in
+// the chain.
+type decoratedHandler struct {
+	// The next handler to be called.
+	Next Handler
+
+	// The current middleware decorating the handler.
+	With Middleware
+}
+
+// Handle implements the Handler interface to handle a operation invocation.
+func (m decoratedHandler) Handle(ctx context.Context, input interface{}) (
+	output interface{}, metadata Metadata, err error,
+) {
+	return m.With.HandleMiddleware(ctx, input, m.Next)
+}
+
+// DecorateHandler decorates a handler with a middleware. Wrapping the handler
+// with the middleware.
+func DecorateHandler(h Handler, with ...Middleware) Handler {
+	for i := len(with) - 1; i >= 0; i-- {
+		h = decoratedHandler{
+			Next: h,
+			With: with[i],
+		}
+	}
+
+	return h
+}

vendor/github.com/aws/smithy-go/middleware/ordered_group.go

@@ -0,0 +1,268 @@
+package middleware
+
+import "fmt"
+
+// RelativePosition provides specifying the relative position of a middleware
+// in an ordered group.
+type RelativePosition int
+
+// Relative position for middleware in steps.
+const (
+	After RelativePosition = iota
+	Before
+)
+
+type ider interface {
+	ID() string
+}
+
+// orderedIDs provides an ordered collection of items with relative ordering
+// by name.
+type orderedIDs struct {
+	order *relativeOrder
+	items map[string]ider
+}
+
+const baseOrderedItems = 5
+
+func newOrderedIDs() *orderedIDs {
+	return &orderedIDs{
+		order: newRelativeOrder(),
+		items: make(map[string]ider, baseOrderedItems),
+	}
+}
+
+// Add injects the item to the relative position of the item group. Returns an
+// error if the item already exists.
+func (g *orderedIDs) Add(m ider, pos RelativePosition) error {
+	id := m.ID()
+	if len(id) == 0 {
+		return fmt.Errorf("empty ID, ID must not be empty")
+	}
+
+	if err := g.order.Add(pos, id); err != nil {
+		return err
+	}
+
+	g.items[id] = m
+	return nil
+}
+
+// Insert injects the item relative to an existing item id. Returns an error if
+// the original item does not exist, or the item being added already exists.
+func (g *orderedIDs) Insert(m ider, relativeTo string, pos RelativePosition) error {
+	if len(m.ID()) == 0 {
+		return fmt.Errorf("insert ID must not be empty")
+	}
+	if len(relativeTo) == 0 {
+		return fmt.Errorf("relative to ID must not be empty")
+	}
+
+	if err := g.order.Insert(relativeTo, pos, m.ID()); err != nil {
+		return err
+	}
+
+	g.items[m.ID()] = m
+	return nil
+}
+
+// Get returns the ider identified by id. If ider is not present, returns false.
+func (g *orderedIDs) Get(id string) (ider, bool) {
+	v, ok := g.items[id]
+	return v, ok
+}
+
+// Swap removes the item by id, replacing it with the new item. Returns an error
+// if the original item doesn't exist.
+func (g *orderedIDs) Swap(id string, m ider) (ider, error) {
+	if len(id) == 0 {
+		return nil, fmt.Errorf("swap from ID must not be empty")
+	}
+
+	iderID := m.ID()
+	if len(iderID) == 0 {
+		return nil, fmt.Errorf("swap to ID must not be empty")
+	}
+
+	if err := g.order.Swap(id, iderID); err != nil {
+		return nil, err
+	}
+
+	removed := g.items[id]
+
+	delete(g.items, id)
+	g.items[iderID] = m
+
+	return removed, nil
+}
+
+// Remove removes the item by id. Returns an error if the item
+// doesn't exist.
+func (g *orderedIDs) Remove(id string) (ider, error) {
+	if len(id) == 0 {
+		return nil, fmt.Errorf("remove ID must not be empty")
+	}
+
+	if err := g.order.Remove(id); err != nil {
+		return nil, err
+	}
+
+	removed := g.items[id]
+	delete(g.items, id)
+	return removed, nil
+}
+
+func (g *orderedIDs) List() []string {
+	items := g.order.List()
+	order := make([]string, len(items))
+	copy(order, items)
+	return order
+}
+
+// Clear removes all entries and slots.
+func (g *orderedIDs) Clear() {
+	g.order.Clear()
+	g.items = map[string]ider{}
+}
+
+// GetOrder returns the item in the order it should be invoked in.
+func (g *orderedIDs) GetOrder() []interface{} {
+	order := g.order.List()
+	ordered := make([]interface{}, len(order))
+	for i := 0; i < len(order); i++ {
+		ordered[i] = g.items[order[i]]
+	}
+
+	return ordered
+}
+
+// relativeOrder provides ordering of item
+type relativeOrder struct {
+	order []string
+}
+
+func newRelativeOrder() *relativeOrder {
+	return &relativeOrder{
+		order: make([]string, 0, baseOrderedItems),
+	}
+}
+
+// Add inserts an item into the order relative to the position provided.
+func (s *relativeOrder) Add(pos RelativePosition, ids ...string) error {
+	if len(ids) == 0 {
+		return nil
+	}
+
+	for _, id := range ids {
+		if _, ok := s.has(id); ok {
+			return fmt.Errorf("already exists, %v", id)
+		}
+	}
+
+	switch pos {
+	case Before:
+		return s.insert(0, Before, ids...)
+
+	case After:
+		s.order = append(s.order, ids...)
+
+	default:
+		return fmt.Errorf("invalid position, %v", int(pos))
+	}
+
+	return nil
+}
+
+// Insert injects an item before or after the relative item. Returns
+// an error if the relative item does not exist.
+func (s *relativeOrder) Insert(relativeTo string, pos RelativePosition, ids ...string) error {
+	if len(ids) == 0 {
+		return nil
+	}
+
+	for _, id := range ids {
+		if _, ok := s.has(id); ok {
+			return fmt.Errorf("already exists, %v", id)
+		}
+	}
+
+	i, ok := s.has(relativeTo)
+	if !ok {
+		return fmt.Errorf("not found, %v", relativeTo)
+	}
+
+	return s.insert(i, pos, ids...)
+}
+
+// Swap will replace the item id with the to item. Returns an
+// error if the original item id does not exist. Allows swapping out an
+// item for another item with the same id.
+func (s *relativeOrder) Swap(id, to string) error {
+	i, ok := s.has(id)
+	if !ok {
+		return fmt.Errorf("not found, %v", id)
+	}
+
+	if _, ok = s.has(to); ok && id != to {
+		return fmt.Errorf("already exists, %v", to)
+	}
+
+	s.order[i] = to
+	return nil
+}
+
+func (s *relativeOrder) Remove(id string) error {
+	i, ok := s.has(id)
+	if !ok {
+		return fmt.Errorf("not found, %v", id)
+	}
+
+	s.order = append(s.order[:i], s.order[i+1:]...)
+	return nil
+}
+
+func (s *relativeOrder) List() []string {
+	return s.order
+}
+
+func (s *relativeOrder) Clear() {
+	s.order = s.order[0:0]
+}
+
+func (s *relativeOrder) insert(i int, pos RelativePosition, ids ...string) error {
+	switch pos {
+	case Before:
+		n := len(ids)
+		var src []string
+		if n <= cap(s.order)-len(s.order) {
+			s.order = s.order[:len(s.order)+n]
+			src = s.order
+		} else {
+			src = s.order
+			s.order = make([]string, len(s.order)+n)
+			copy(s.order[:i], src[:i]) // only when allocating a new slice do we need to copy the front half
+		}
+		copy(s.order[i+n:], src[i:])
+		copy(s.order[i:], ids)
+	case After:
+		if i == len(s.order)-1 || len(s.order) == 0 {
+			s.order = append(s.order, ids...)
+		} else {
+			s.order = append(s.order[:i+1], append(ids, s.order[i+1:]...)...)
+		}
+
+	default:
+		return fmt.Errorf("invalid position, %v", int(pos))
+	}
+
+	return nil
+}
+
+func (s *relativeOrder) has(id string) (i int, found bool) {
+	for i := 0; i < len(s.order); i++ {
+		if s.order[i] == id {
+			return i, true
+		}
+	}
+	return 0, false
+}

vendor/github.com/aws/smithy-go/middleware/stack.go

@@ -0,0 +1,209 @@
+package middleware
+
+import (
+	"context"
+	"io"
+	"strings"
+)
+
+// Stack provides protocol and transport agnostic set of middleware split into
+// distinct steps. Steps have specific transitions between them, that are
+// managed by the individual step.
+//
+// Steps are composed as middleware around the underlying handler in the
+// following order:
+//
+//   Initialize -> Serialize -> Build -> Finalize -> Deserialize -> Handler
+//
+// Any middleware within the chain may choose to stop and return an error or
+// response. Since the middleware decorate the handler like a call stack, each
+// middleware will receive the result of the next middleware in the chain.
+// Middleware that does not need to react to an input, or result must forward
+// along the input down the chain, or return the result back up the chain.
+//
+//   Initialize <- Serialize -> Build -> Finalize <- Deserialize <- Handler
+type Stack struct {
+	// Initialize prepares the input, and sets any default parameters as
+	// needed, (e.g. idempotency token, and presigned URLs).
+	//
+	// Takes Input Parameters, and returns result or error.
+	//
+	// Receives result or error from Serialize step.
+	Initialize *InitializeStep
+
+	// Serialize serializes the prepared input into a data structure that can be consumed
+	// by the target transport's message, (e.g. REST-JSON serialization)
+	//
+	// Converts Input Parameters into a Request, and returns the result or error.
+	//
+	// Receives result or error from Build step.
+	Serialize *SerializeStep
+
+	// Build adds additional metadata to the serialized transport message
+	// (e.g. HTTP's Content-Length header, or body checksum). Decorations and
+	// modifications to the message should be copied to all message attempts.
+	//
+	// Takes Request, and returns result or error.
+	//
+	// Receives result or error from Finalize step.
+	Build *BuildStep
+
+	// Finalize performs final preparations needed before sending the message. The
+	// message should already be complete by this stage, and is only alternated
+	// to meet the expectations of the recipient (e.g. Retry and AWS SigV4
+	// request signing)
+	//
+	// Takes Request, and returns result or error.
+	//
+	// Receives result or error from Deserialize step.
+	Finalize *FinalizeStep
+
+	// Deserialize reacts to the handler's response returned by the recipient of the request
+	// message. Deserializes the response into a structured type or error above
+	// stacks can react to.
+	//
+	// Should only forward Request to underlying handler.
+	//
+	// Takes Request, and returns result or error.
+	//
+	// Receives raw response, or error from underlying handler.
+	Deserialize *DeserializeStep
+
+	id string
+}
+
+// NewStack returns an initialize empty stack.
+func NewStack(id string, newRequestFn func() interface{}) *Stack {
+	return &Stack{
+		id:          id,
+		Initialize:  NewInitializeStep(),
+		Serialize:   NewSerializeStep(newRequestFn),
+		Build:       NewBuildStep(),
+		Finalize:    NewFinalizeStep(),
+		Deserialize: NewDeserializeStep(),
+	}
+}
+
+// ID returns the unique ID for the stack as a middleware.
+func (s *Stack) ID() string { return s.id }
+
+// HandleMiddleware invokes the middleware stack decorating the next handler.
+// Each step of stack will be invoked in order before calling the next step.
+// With the next handler call last.
+//
+// The input value must be the input parameters of the operation being
+// performed.
+//
+// Will return the result of the operation, or error.
+func (s *Stack) HandleMiddleware(ctx context.Context, input interface{}, next Handler) (
+	output interface{}, metadata Metadata, err error,
+) {
+	h := DecorateHandler(next,
+		s.Initialize,
+		s.Serialize,
+		s.Build,
+		s.Finalize,
+		s.Deserialize,
+	)
+
+	return h.Handle(ctx, input)
+}
+
+// List returns a list of all middleware in the stack by step.
+func (s *Stack) List() []string {
+	var l []string
+	l = append(l, s.id)
+
+	l = append(l, s.Initialize.ID())
+	l = append(l, s.Initialize.List()...)
+
+	l = append(l, s.Serialize.ID())
+	l = append(l, s.Serialize.List()...)
+
+	l = append(l, s.Build.ID())
+	l = append(l, s.Build.List()...)
+
+	l = append(l, s.Finalize.ID())
+	l = append(l, s.Finalize.List()...)
+
+	l = append(l, s.Deserialize.ID())
+	l = append(l, s.Deserialize.List()...)
+
+	return l
+}
+
+func (s *Stack) String() string {
+	var b strings.Builder
+
+	w := &indentWriter{w: &b}
+
+	w.WriteLine(s.id)
+	w.Push()
+
+	writeStepItems(w, s.Initialize)
+	writeStepItems(w, s.Serialize)
+	writeStepItems(w, s.Build)
+	writeStepItems(w, s.Finalize)
+	writeStepItems(w, s.Deserialize)
+
+	return b.String()
+}
+
+type stackStepper interface {
+	ID() string
+	List() []string
+}
+
+func writeStepItems(w *indentWriter, s stackStepper) {
+	type lister interface {
+		List() []string
+	}
+
+	w.WriteLine(s.ID())
+	w.Push()
+
+	defer w.Pop()
+
+	// ignore stack to prevent circular iterations
+	if _, ok := s.(*Stack); ok {
+		return
+	}
+
+	for _, id := range s.List() {
+		w.WriteLine(id)
+	}
+}
+
+type stringWriter interface {
+	io.Writer
+	WriteString(string) (int, error)
+	WriteRune(rune) (int, error)
+}
+
+type indentWriter struct {
+	w     stringWriter
+	depth int
+}
+
+const indentDepth = "\t\t\t\t\t\t\t\t\t\t"
+
+func (w *indentWriter) Push() {
+	w.depth++
+}
+
+func (w *indentWriter) Pop() {
+	w.depth--
+	if w.depth < 0 {
+		w.depth = 0
+	}
+}
+
+func (w *indentWriter) WriteLine(v string) {
+	w.w.WriteString(indentDepth[:w.depth])
+
+	v = strings.ReplaceAll(v, "\n", "\\n")
+	v = strings.ReplaceAll(v, "\r", "\\r")
+
+	w.w.WriteString(v)
+	w.w.WriteRune('\n')
+}

vendor/github.com/aws/smithy-go/middleware/stack_values.go

@@ -0,0 +1,100 @@
+package middleware
+
+import (
+	"context"
+	"reflect"
+	"strings"
+)
+
+// WithStackValue adds a key value pair to the context that is intended to be
+// scoped to a stack. Use ClearStackValues to get a new context with all stack
+// values cleared.
+func WithStackValue(ctx context.Context, key, value interface{}) context.Context {
+	md, _ := ctx.Value(stackValuesKey{}).(*stackValues)
+
+	md = withStackValue(md, key, value)
+	return context.WithValue(ctx, stackValuesKey{}, md)
+}
+
+// ClearStackValues returns a context without any stack values.
+func ClearStackValues(ctx context.Context) context.Context {
+	return context.WithValue(ctx, stackValuesKey{}, nil)
+}
+
+// GetStackValues returns the value pointed to by the key within the stack
+// values, if it is present.
+func GetStackValue(ctx context.Context, key interface{}) interface{} {
+	md, _ := ctx.Value(stackValuesKey{}).(*stackValues)
+	if md == nil {
+		return nil
+	}
+
+	return md.Value(key)
+}
+
+type stackValuesKey struct{}
+
+type stackValues struct {
+	key    interface{}
+	value  interface{}
+	parent *stackValues
+}
+
+func withStackValue(parent *stackValues, key, value interface{}) *stackValues {
+	if key == nil {
+		panic("nil key")
+	}
+	if !reflect.TypeOf(key).Comparable() {
+		panic("key is not comparable")
+	}
+	return &stackValues{key: key, value: value, parent: parent}
+}
+
+func (m *stackValues) Value(key interface{}) interface{} {
+	if key == m.key {
+		return m.value
+	}
+
+	if m.parent == nil {
+		return nil
+	}
+
+	return m.parent.Value(key)
+}
+
+func (c *stackValues) String() string {
+	var str strings.Builder
+
+	cc := c
+	for cc == nil {
+		str.WriteString("(" +
+			reflect.TypeOf(c.key).String() +
+			": " +
+			stringify(cc.value) +
+			")")
+		if cc.parent != nil {
+			str.WriteString(" -> ")
+		}
+		cc = cc.parent
+	}
+	str.WriteRune('}')
+
+	return str.String()
+}
+
+type stringer interface {
+	String() string
+}
+
+// stringify tries a bit to stringify v, without using fmt, since we don't
+// want context depending on the unicode tables. This is only used by
+// *valueCtx.String().
+func stringify(v interface{}) string {
+	switch s := v.(type) {
+	case stringer:
+		return s.String()
+	case string:
+		return s
+	}
+	return "<not Stringer>"
+}

vendor/github.com/aws/smithy-go/middleware/step_build.go

@@ -0,0 +1,211 @@
+package middleware
+
+import (
+	"context"
+)
+
+// BuildInput provides the input parameters for the BuildMiddleware to consume.
+// BuildMiddleware may modify the Request value before forwarding the input
+// along to the next BuildHandler.
+type BuildInput struct {
+	Request interface{}
+}
+
+// BuildOutput provides the result returned by the next BuildHandler.
+type BuildOutput struct {
+	Result interface{}
+}
+
+// BuildHandler provides the interface for the next handler the
+// BuildMiddleware will call in the middleware chain.
+type BuildHandler interface {
+	HandleBuild(ctx context.Context, in BuildInput) (
+		out BuildOutput, metadata Metadata, err error,
+	)
+}
+
+// BuildMiddleware provides the interface for middleware specific to the
+// serialize step. Delegates to the next BuildHandler for further
+// processing.
+type BuildMiddleware interface {
+	// Unique ID for the middleware in theBuildStep. The step does not allow
+	// duplicate IDs.
+	ID() string
+
+	// Invokes the middleware behavior which must delegate to the next handler
+	// for the middleware chain to continue. The method must return a result or
+	// error to its caller.
+	HandleBuild(ctx context.Context, in BuildInput, next BuildHandler) (
+		out BuildOutput, metadata Metadata, err error,
+	)
+}
+
+// BuildMiddlewareFunc returns a BuildMiddleware with the unique ID provided,
+// and the func to be invoked.
+func BuildMiddlewareFunc(id string, fn func(context.Context, BuildInput, BuildHandler) (BuildOutput, Metadata, error)) BuildMiddleware {
+	return buildMiddlewareFunc{
+		id: id,
+		fn: fn,
+	}
+}
+
+type buildMiddlewareFunc struct {
+	// Unique ID for the middleware.
+	id string
+
+	// Middleware function to be called.
+	fn func(context.Context, BuildInput, BuildHandler) (BuildOutput, Metadata, error)
+}
+
+// ID returns the unique ID for the middleware.
+func (s buildMiddlewareFunc) ID() string { return s.id }
+
+// HandleBuild invokes the middleware Fn.
+func (s buildMiddlewareFunc) HandleBuild(ctx context.Context, in BuildInput, next BuildHandler) (
+	out BuildOutput, metadata Metadata, err error,
+) {
+	return s.fn(ctx, in, next)
+}
+
+var _ BuildMiddleware = (buildMiddlewareFunc{})
+
+// BuildStep provides the ordered grouping of BuildMiddleware to be invoked on
+// a handler.
+type BuildStep struct {
+	ids *orderedIDs
+}
+
+// NewBuildStep returns a BuildStep ready to have middleware for
+// initialization added to it.
+func NewBuildStep() *BuildStep {
+	return &BuildStep{
+		ids: newOrderedIDs(),
+	}
+}
+
+var _ Middleware = (*BuildStep)(nil)
+
+// ID returns the unique name of the step as a middleware.
+func (s *BuildStep) ID() string {
+	return "Build stack step"
+}
+
+// HandleMiddleware invokes the middleware by decorating the next handler
+// provided. Returns the result of the middleware and handler being invoked.
+//
+// Implements Middleware interface.
+func (s *BuildStep) HandleMiddleware(ctx context.Context, in interface{}, next Handler) (
+	out interface{}, metadata Metadata, err error,
+) {
+	order := s.ids.GetOrder()
+
+	var h BuildHandler = buildWrapHandler{Next: next}
+	for i := len(order) - 1; i >= 0; i-- {
+		h = decoratedBuildHandler{
+			Next: h,
+			With: order[i].(BuildMiddleware),
+		}
+	}
+
+	sIn := BuildInput{
+		Request: in,
+	}
+
+	res, metadata, err := h.HandleBuild(ctx, sIn)
+	return res.Result, metadata, err
+}
+
+// Get retrieves the middleware identified by id. If the middleware is not present, returns false.
+func (s *BuildStep) Get(id string) (BuildMiddleware, bool) {
+	get, ok := s.ids.Get(id)
+	if !ok {
+		return nil, false
+	}
+	return get.(BuildMiddleware), ok
+}
+
+// Add injects the middleware to the relative position of the middleware group.
+// Returns an error if the middleware already exists.
+func (s *BuildStep) Add(m BuildMiddleware, pos RelativePosition) error {
+	return s.ids.Add(m, pos)
+}
+
+// Insert injects the middleware relative to an existing middleware id.
+// Returns an error if the original middleware does not exist, or the middleware
+// being added already exists.
+func (s *BuildStep) Insert(m BuildMiddleware, relativeTo string, pos RelativePosition) error {
+	return s.ids.Insert(m, relativeTo, pos)
+}
+
+// Swap removes the middleware by id, replacing it with the new middleware.
+// Returns the middleware removed, or an error if the middleware to be removed
+// doesn't exist.
+func (s *BuildStep) Swap(id string, m BuildMiddleware) (BuildMiddleware, error) {
+	removed, err := s.ids.Swap(id, m)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(BuildMiddleware), nil
+}
+
+// Remove removes the middleware by id. Returns error if the middleware
+// doesn't exist.
+func (s *BuildStep) Remove(id string) (BuildMiddleware, error) {
+	removed, err := s.ids.Remove(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(BuildMiddleware), nil
+}
+
+// List returns a list of the middleware in the step.
+func (s *BuildStep) List() []string {
+	return s.ids.List()
+}
+
+// Clear removes all middleware in the step.
+func (s *BuildStep) Clear() {
+	s.ids.Clear()
+}
+
+type buildWrapHandler struct {
+	Next Handler
+}
+
+var _ BuildHandler = (*buildWrapHandler)(nil)
+
+// Implements BuildHandler, converts types and delegates to underlying
+// generic handler.
+func (w buildWrapHandler) HandleBuild(ctx context.Context, in BuildInput) (
+	out BuildOutput, metadata Metadata, err error,
+) {
+	res, metadata, err := w.Next.Handle(ctx, in.Request)
+	return BuildOutput{
+		Result: res,
+	}, metadata, err
+}
+
+type decoratedBuildHandler struct {
+	Next BuildHandler
+	With BuildMiddleware
+}
+
+var _ BuildHandler = (*decoratedBuildHandler)(nil)
+
+func (h decoratedBuildHandler) HandleBuild(ctx context.Context, in BuildInput) (
+	out BuildOutput, metadata Metadata, err error,
+) {
+	return h.With.HandleBuild(ctx, in, h.Next)
+}
+
+// BuildHandlerFunc provides a wrapper around a function to be used as a build middleware handler.
+type BuildHandlerFunc func(context.Context, BuildInput) (BuildOutput, Metadata, error)
+
+// HandleBuild invokes the wrapped function with the provided arguments.
+func (b BuildHandlerFunc) HandleBuild(ctx context.Context, in BuildInput) (BuildOutput, Metadata, error) {
+	return b(ctx, in)
+}
+
+var _ BuildHandler = BuildHandlerFunc(nil)

vendor/github.com/aws/smithy-go/middleware/step_deserialize.go

@@ -0,0 +1,217 @@
+package middleware
+
+import (
+	"context"
+)
+
+// DeserializeInput provides the input parameters for the DeserializeInput to
+// consume. DeserializeMiddleware should not modify the Request, and instead
+// forward it along to the next DeserializeHandler.
+type DeserializeInput struct {
+	Request interface{}
+}
+
+// DeserializeOutput provides the result returned by the next
+// DeserializeHandler. The DeserializeMiddleware should deserialize the
+// RawResponse into a Result that can be consumed by middleware higher up in
+// the stack.
+type DeserializeOutput struct {
+	RawResponse interface{}
+	Result      interface{}
+}
+
+// DeserializeHandler provides the interface for the next handler the
+// DeserializeMiddleware will call in the middleware chain.
+type DeserializeHandler interface {
+	HandleDeserialize(ctx context.Context, in DeserializeInput) (
+		out DeserializeOutput, metadata Metadata, err error,
+	)
+}
+
+// DeserializeMiddleware provides the interface for middleware specific to the
+// serialize step. Delegates to the next DeserializeHandler for further
+// processing.
+type DeserializeMiddleware interface {
+	// ID returns a unique ID for the middleware in the DeserializeStep. The step does not
+	// allow duplicate IDs.
+	ID() string
+
+	// HandleDeserialize invokes the middleware behavior which must delegate to the next handler
+	// for the middleware chain to continue. The method must return a result or
+	// error to its caller.
+	HandleDeserialize(ctx context.Context, in DeserializeInput, next DeserializeHandler) (
+		out DeserializeOutput, metadata Metadata, err error,
+	)
+}
+
+// DeserializeMiddlewareFunc returns a DeserializeMiddleware with the unique ID
+// provided, and the func to be invoked.
+func DeserializeMiddlewareFunc(id string, fn func(context.Context, DeserializeInput, DeserializeHandler) (DeserializeOutput, Metadata, error)) DeserializeMiddleware {
+	return deserializeMiddlewareFunc{
+		id: id,
+		fn: fn,
+	}
+}
+
+type deserializeMiddlewareFunc struct {
+	// Unique ID for the middleware.
+	id string
+
+	// Middleware function to be called.
+	fn func(context.Context, DeserializeInput, DeserializeHandler) (
+		DeserializeOutput, Metadata, error,
+	)
+}
+
+// ID returns the unique ID for the middleware.
+func (s deserializeMiddlewareFunc) ID() string { return s.id }
+
+// HandleDeserialize invokes the middleware Fn.
+func (s deserializeMiddlewareFunc) HandleDeserialize(ctx context.Context, in DeserializeInput, next DeserializeHandler) (
+	out DeserializeOutput, metadata Metadata, err error,
+) {
+	return s.fn(ctx, in, next)
+}
+
+var _ DeserializeMiddleware = (deserializeMiddlewareFunc{})
+
+// DeserializeStep provides the ordered grouping of DeserializeMiddleware to be
+// invoked on a handler.
+type DeserializeStep struct {
+	ids *orderedIDs
+}
+
+// NewDeserializeStep returns a DeserializeStep ready to have middleware for
+// initialization added to it.
+func NewDeserializeStep() *DeserializeStep {
+	return &DeserializeStep{
+		ids: newOrderedIDs(),
+	}
+}
+
+var _ Middleware = (*DeserializeStep)(nil)
+
+// ID returns the unique ID of the step as a middleware.
+func (s *DeserializeStep) ID() string {
+	return "Deserialize stack step"
+}
+
+// HandleMiddleware invokes the middleware by decorating the next handler
+// provided. Returns the result of the middleware and handler being invoked.
+//
+// Implements Middleware interface.
+func (s *DeserializeStep) HandleMiddleware(ctx context.Context, in interface{}, next Handler) (
+	out interface{}, metadata Metadata, err error,
+) {
+	order := s.ids.GetOrder()
+
+	var h DeserializeHandler = deserializeWrapHandler{Next: next}
+	for i := len(order) - 1; i >= 0; i-- {
+		h = decoratedDeserializeHandler{
+			Next: h,
+			With: order[i].(DeserializeMiddleware),
+		}
+	}
+
+	sIn := DeserializeInput{
+		Request: in,
+	}
+
+	res, metadata, err := h.HandleDeserialize(ctx, sIn)
+	return res.Result, metadata, err
+}
+
+// Get retrieves the middleware identified by id. If the middleware is not present, returns false.
+func (s *DeserializeStep) Get(id string) (DeserializeMiddleware, bool) {
+	get, ok := s.ids.Get(id)
+	if !ok {
+		return nil, false
+	}
+	return get.(DeserializeMiddleware), ok
+}
+
+// Add injects the middleware to the relative position of the middleware group.
+// Returns an error if the middleware already exists.
+func (s *DeserializeStep) Add(m DeserializeMiddleware, pos RelativePosition) error {
+	return s.ids.Add(m, pos)
+}
+
+// Insert injects the middleware relative to an existing middleware ID.
+// Returns error if the original middleware does not exist, or the middleware
+// being added already exists.
+func (s *DeserializeStep) Insert(m DeserializeMiddleware, relativeTo string, pos RelativePosition) error {
+	return s.ids.Insert(m, relativeTo, pos)
+}
+
+// Swap removes the middleware by id, replacing it with the new middleware.
+// Returns the middleware removed, or error if the middleware to be removed
+// doesn't exist.
+func (s *DeserializeStep) Swap(id string, m DeserializeMiddleware) (DeserializeMiddleware, error) {
+	removed, err := s.ids.Swap(id, m)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(DeserializeMiddleware), nil
+}
+
+// Remove removes the middleware by id. Returns error if the middleware
+// doesn't exist.
+func (s *DeserializeStep) Remove(id string) (DeserializeMiddleware, error) {
+	removed, err := s.ids.Remove(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(DeserializeMiddleware), nil
+}
+
+// List returns a list of the middleware in the step.
+func (s *DeserializeStep) List() []string {
+	return s.ids.List()
+}
+
+// Clear removes all middleware in the step.
+func (s *DeserializeStep) Clear() {
+	s.ids.Clear()
+}
+
+type deserializeWrapHandler struct {
+	Next Handler
+}
+
+var _ DeserializeHandler = (*deserializeWrapHandler)(nil)
+
+// HandleDeserialize implements DeserializeHandler, converts types and delegates to underlying
+// generic handler.
+func (w deserializeWrapHandler) HandleDeserialize(ctx context.Context, in DeserializeInput) (
+	out DeserializeOutput, metadata Metadata, err error,
+) {
+	resp, metadata, err := w.Next.Handle(ctx, in.Request)
+	return DeserializeOutput{
+		RawResponse: resp,
+	}, metadata, err
+}
+
+type decoratedDeserializeHandler struct {
+	Next DeserializeHandler
+	With DeserializeMiddleware
+}
+
+var _ DeserializeHandler = (*decoratedDeserializeHandler)(nil)
+
+func (h decoratedDeserializeHandler) HandleDeserialize(ctx context.Context, in DeserializeInput) (
+	out DeserializeOutput, metadata Metadata, err error,
+) {
+	return h.With.HandleDeserialize(ctx, in, h.Next)
+}
+
+// DeserializeHandlerFunc provides a wrapper around a function to be used as a deserialize middleware handler.
+type DeserializeHandlerFunc func(context.Context, DeserializeInput) (DeserializeOutput, Metadata, error)
+
+// HandleDeserialize invokes the wrapped function with the given arguments.
+func (d DeserializeHandlerFunc) HandleDeserialize(ctx context.Context, in DeserializeInput) (DeserializeOutput, Metadata, error) {
+	return d(ctx, in)
+}
+
+var _ DeserializeHandler = DeserializeHandlerFunc(nil)

vendor/github.com/aws/smithy-go/middleware/step_finalize.go

@@ -0,0 +1,211 @@
+package middleware
+
+import "context"
+
+// FinalizeInput provides the input parameters for the FinalizeMiddleware to
+// consume. FinalizeMiddleware may modify the Request value before forwarding
+// the FinalizeInput along to the next next FinalizeHandler.
+type FinalizeInput struct {
+	Request interface{}
+}
+
+// FinalizeOutput provides the result returned by the next FinalizeHandler.
+type FinalizeOutput struct {
+	Result interface{}
+}
+
+// FinalizeHandler provides the interface for the next handler the
+// FinalizeMiddleware will call in the middleware chain.
+type FinalizeHandler interface {
+	HandleFinalize(ctx context.Context, in FinalizeInput) (
+		out FinalizeOutput, metadata Metadata, err error,
+	)
+}
+
+// FinalizeMiddleware provides the interface for middleware specific to the
+// serialize step. Delegates to the next FinalizeHandler for further
+// processing.
+type FinalizeMiddleware interface {
+	// ID returns a unique ID for the middleware in the FinalizeStep. The step does not
+	// allow duplicate IDs.
+	ID() string
+
+	// HandleFinalize invokes the middleware behavior which must delegate to the next handler
+	// for the middleware chain to continue. The method must return a result or
+	// error to its caller.
+	HandleFinalize(ctx context.Context, in FinalizeInput, next FinalizeHandler) (
+		out FinalizeOutput, metadata Metadata, err error,
+	)
+}
+
+// FinalizeMiddlewareFunc returns a FinalizeMiddleware with the unique ID
+// provided, and the func to be invoked.
+func FinalizeMiddlewareFunc(id string, fn func(context.Context, FinalizeInput, FinalizeHandler) (FinalizeOutput, Metadata, error)) FinalizeMiddleware {
+	return finalizeMiddlewareFunc{
+		id: id,
+		fn: fn,
+	}
+}
+
+type finalizeMiddlewareFunc struct {
+	// Unique ID for the middleware.
+	id string
+
+	// Middleware function to be called.
+	fn func(context.Context, FinalizeInput, FinalizeHandler) (
+		FinalizeOutput, Metadata, error,
+	)
+}
+
+// ID returns the unique ID for the middleware.
+func (s finalizeMiddlewareFunc) ID() string { return s.id }
+
+// HandleFinalize invokes the middleware Fn.
+func (s finalizeMiddlewareFunc) HandleFinalize(ctx context.Context, in FinalizeInput, next FinalizeHandler) (
+	out FinalizeOutput, metadata Metadata, err error,
+) {
+	return s.fn(ctx, in, next)
+}
+
+var _ FinalizeMiddleware = (finalizeMiddlewareFunc{})
+
+// FinalizeStep provides the ordered grouping of FinalizeMiddleware to be
+// invoked on a handler.
+type FinalizeStep struct {
+	ids *orderedIDs
+}
+
+// NewFinalizeStep returns a FinalizeStep ready to have middleware for
+// initialization added to it.
+func NewFinalizeStep() *FinalizeStep {
+	return &FinalizeStep{
+		ids: newOrderedIDs(),
+	}
+}
+
+var _ Middleware = (*FinalizeStep)(nil)
+
+// ID returns the unique id of the step as a middleware.
+func (s *FinalizeStep) ID() string {
+	return "Finalize stack step"
+}
+
+// HandleMiddleware invokes the middleware by decorating the next handler
+// provided. Returns the result of the middleware and handler being invoked.
+//
+// Implements Middleware interface.
+func (s *FinalizeStep) HandleMiddleware(ctx context.Context, in interface{}, next Handler) (
+	out interface{}, metadata Metadata, err error,
+) {
+	order := s.ids.GetOrder()
+
+	var h FinalizeHandler = finalizeWrapHandler{Next: next}
+	for i := len(order) - 1; i >= 0; i-- {
+		h = decoratedFinalizeHandler{
+			Next: h,
+			With: order[i].(FinalizeMiddleware),
+		}
+	}
+
+	sIn := FinalizeInput{
+		Request: in,
+	}
+
+	res, metadata, err := h.HandleFinalize(ctx, sIn)
+	return res.Result, metadata, err
+}
+
+// Get retrieves the middleware identified by id. If the middleware is not present, returns false.
+func (s *FinalizeStep) Get(id string) (FinalizeMiddleware, bool) {
+	get, ok := s.ids.Get(id)
+	if !ok {
+		return nil, false
+	}
+	return get.(FinalizeMiddleware), ok
+}
+
+// Add injects the middleware to the relative position of the middleware group.
+// Returns an error if the middleware already exists.
+func (s *FinalizeStep) Add(m FinalizeMiddleware, pos RelativePosition) error {
+	return s.ids.Add(m, pos)
+}
+
+// Insert injects the middleware relative to an existing middleware ID.
+// Returns error if the original middleware does not exist, or the middleware
+// being added already exists.
+func (s *FinalizeStep) Insert(m FinalizeMiddleware, relativeTo string, pos RelativePosition) error {
+	return s.ids.Insert(m, relativeTo, pos)
+}
+
+// Swap removes the middleware by id, replacing it with the new middleware.
+// Returns the middleware removed, or error if the middleware to be removed
+// doesn't exist.
+func (s *FinalizeStep) Swap(id string, m FinalizeMiddleware) (FinalizeMiddleware, error) {
+	removed, err := s.ids.Swap(id, m)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(FinalizeMiddleware), nil
+}
+
+// Remove removes the middleware by id. Returns error if the middleware
+// doesn't exist.
+func (s *FinalizeStep) Remove(id string) (FinalizeMiddleware, error) {
+	removed, err := s.ids.Remove(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(FinalizeMiddleware), nil
+}
+
+// List returns a list of the middleware in the step.
+func (s *FinalizeStep) List() []string {
+	return s.ids.List()
+}
+
+// Clear removes all middleware in the step.
+func (s *FinalizeStep) Clear() {
+	s.ids.Clear()
+}
+
+type finalizeWrapHandler struct {
+	Next Handler
+}
+
+var _ FinalizeHandler = (*finalizeWrapHandler)(nil)
+
+// HandleFinalize implements FinalizeHandler, converts types and delegates to underlying
+// generic handler.
+func (w finalizeWrapHandler) HandleFinalize(ctx context.Context, in FinalizeInput) (
+	out FinalizeOutput, metadata Metadata, err error,
+) {
+	res, metadata, err := w.Next.Handle(ctx, in.Request)
+	return FinalizeOutput{
+		Result: res,
+	}, metadata, err
+}
+
+type decoratedFinalizeHandler struct {
+	Next FinalizeHandler
+	With FinalizeMiddleware
+}
+
+var _ FinalizeHandler = (*decoratedFinalizeHandler)(nil)
+
+func (h decoratedFinalizeHandler) HandleFinalize(ctx context.Context, in FinalizeInput) (
+	out FinalizeOutput, metadata Metadata, err error,
+) {
+	return h.With.HandleFinalize(ctx, in, h.Next)
+}
+
+// FinalizeHandlerFunc provides a wrapper around a function to be used as a finalize middleware handler.
+type FinalizeHandlerFunc func(context.Context, FinalizeInput) (FinalizeOutput, Metadata, error)
+
+// HandleFinalize invokes the wrapped function with the given arguments.
+func (f FinalizeHandlerFunc) HandleFinalize(ctx context.Context, in FinalizeInput) (FinalizeOutput, Metadata, error) {
+	return f(ctx, in)
+}
+
+var _ FinalizeHandler = FinalizeHandlerFunc(nil)

vendor/github.com/aws/smithy-go/middleware/step_initialize.go

@@ -0,0 +1,211 @@
+package middleware
+
+import "context"
+
+// InitializeInput wraps the input parameters for the InitializeMiddlewares to
+// consume. InitializeMiddleware may modify the parameter value before
+// forwarding it along to the next InitializeHandler.
+type InitializeInput struct {
+	Parameters interface{}
+}
+
+// InitializeOutput provides the result returned by the next InitializeHandler.
+type InitializeOutput struct {
+	Result interface{}
+}
+
+// InitializeHandler provides the interface for the next handler the
+// InitializeMiddleware will call in the middleware chain.
+type InitializeHandler interface {
+	HandleInitialize(ctx context.Context, in InitializeInput) (
+		out InitializeOutput, metadata Metadata, err error,
+	)
+}
+
+// InitializeMiddleware provides the interface for middleware specific to the
+// initialize step. Delegates to the next InitializeHandler for further
+// processing.
+type InitializeMiddleware interface {
+	// ID returns a unique ID for the middleware in the InitializeStep. The step does not
+	// allow duplicate IDs.
+	ID() string
+
+	// HandleInitialize invokes the middleware behavior which must delegate to the next handler
+	// for the middleware chain to continue. The method must return a result or
+	// error to its caller.
+	HandleInitialize(ctx context.Context, in InitializeInput, next InitializeHandler) (
+		out InitializeOutput, metadata Metadata, err error,
+	)
+}
+
+// InitializeMiddlewareFunc returns a InitializeMiddleware with the unique ID provided,
+// and the func to be invoked.
+func InitializeMiddlewareFunc(id string, fn func(context.Context, InitializeInput, InitializeHandler) (InitializeOutput, Metadata, error)) InitializeMiddleware {
+	return initializeMiddlewareFunc{
+		id: id,
+		fn: fn,
+	}
+}
+
+type initializeMiddlewareFunc struct {
+	// Unique ID for the middleware.
+	id string
+
+	// Middleware function to be called.
+	fn func(context.Context, InitializeInput, InitializeHandler) (
+		InitializeOutput, Metadata, error,
+	)
+}
+
+// ID returns the unique ID for the middleware.
+func (s initializeMiddlewareFunc) ID() string { return s.id }
+
+// HandleInitialize invokes the middleware Fn.
+func (s initializeMiddlewareFunc) HandleInitialize(ctx context.Context, in InitializeInput, next InitializeHandler) (
+	out InitializeOutput, metadata Metadata, err error,
+) {
+	return s.fn(ctx, in, next)
+}
+
+var _ InitializeMiddleware = (initializeMiddlewareFunc{})
+
+// InitializeStep provides the ordered grouping of InitializeMiddleware to be
+// invoked on a handler.
+type InitializeStep struct {
+	ids *orderedIDs
+}
+
+// NewInitializeStep returns an InitializeStep ready to have middleware for
+// initialization added to it.
+func NewInitializeStep() *InitializeStep {
+	return &InitializeStep{
+		ids: newOrderedIDs(),
+	}
+}
+
+var _ Middleware = (*InitializeStep)(nil)
+
+// ID returns the unique ID of the step as a middleware.
+func (s *InitializeStep) ID() string {
+	return "Initialize stack step"
+}
+
+// HandleMiddleware invokes the middleware by decorating the next handler
+// provided. Returns the result of the middleware and handler being invoked.
+//
+// Implements Middleware interface.
+func (s *InitializeStep) HandleMiddleware(ctx context.Context, in interface{}, next Handler) (
+	out interface{}, metadata Metadata, err error,
+) {
+	order := s.ids.GetOrder()
+
+	var h InitializeHandler = initializeWrapHandler{Next: next}
+	for i := len(order) - 1; i >= 0; i-- {
+		h = decoratedInitializeHandler{
+			Next: h,
+			With: order[i].(InitializeMiddleware),
+		}
+	}
+
+	sIn := InitializeInput{
+		Parameters: in,
+	}
+
+	res, metadata, err := h.HandleInitialize(ctx, sIn)
+	return res.Result, metadata, err
+}
+
+// Get retrieves the middleware identified by id. If the middleware is not present, returns false.
+func (s *InitializeStep) Get(id string) (InitializeMiddleware, bool) {
+	get, ok := s.ids.Get(id)
+	if !ok {
+		return nil, false
+	}
+	return get.(InitializeMiddleware), ok
+}
+
+// Add injects the middleware to the relative position of the middleware group.
+// Returns an error if the middleware already exists.
+func (s *InitializeStep) Add(m InitializeMiddleware, pos RelativePosition) error {
+	return s.ids.Add(m, pos)
+}
+
+// Insert injects the middleware relative to an existing middleware ID.
+// Returns error if the original middleware does not exist, or the middleware
+// being added already exists.
+func (s *InitializeStep) Insert(m InitializeMiddleware, relativeTo string, pos RelativePosition) error {
+	return s.ids.Insert(m, relativeTo, pos)
+}
+
+// Swap removes the middleware by id, replacing it with the new middleware.
+// Returns the middleware removed, or error if the middleware to be removed
+// doesn't exist.
+func (s *InitializeStep) Swap(id string, m InitializeMiddleware) (InitializeMiddleware, error) {
+	removed, err := s.ids.Swap(id, m)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(InitializeMiddleware), nil
+}
+
+// Remove removes the middleware by id. Returns error if the middleware
+// doesn't exist.
+func (s *InitializeStep) Remove(id string) (InitializeMiddleware, error) {
+	removed, err := s.ids.Remove(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(InitializeMiddleware), nil
+}
+
+// List returns a list of the middleware in the step.
+func (s *InitializeStep) List() []string {
+	return s.ids.List()
+}
+
+// Clear removes all middleware in the step.
+func (s *InitializeStep) Clear() {
+	s.ids.Clear()
+}
+
+type initializeWrapHandler struct {
+	Next Handler
+}
+
+var _ InitializeHandler = (*initializeWrapHandler)(nil)
+
+// HandleInitialize implements InitializeHandler, converts types and delegates to underlying
+// generic handler.
+func (w initializeWrapHandler) HandleInitialize(ctx context.Context, in InitializeInput) (
+	out InitializeOutput, metadata Metadata, err error,
+) {
+	res, metadata, err := w.Next.Handle(ctx, in.Parameters)
+	return InitializeOutput{
+		Result: res,
+	}, metadata, err
+}
+
+type decoratedInitializeHandler struct {
+	Next InitializeHandler
+	With InitializeMiddleware
+}
+
+var _ InitializeHandler = (*decoratedInitializeHandler)(nil)
+
+func (h decoratedInitializeHandler) HandleInitialize(ctx context.Context, in InitializeInput) (
+	out InitializeOutput, metadata Metadata, err error,
+) {
+	return h.With.HandleInitialize(ctx, in, h.Next)
+}
+
+// InitializeHandlerFunc provides a wrapper around a function to be used as an initialize middleware handler.
+type InitializeHandlerFunc func(context.Context, InitializeInput) (InitializeOutput, Metadata, error)
+
+// HandleInitialize calls the wrapped function with the provided arguments.
+func (i InitializeHandlerFunc) HandleInitialize(ctx context.Context, in InitializeInput) (InitializeOutput, Metadata, error) {
+	return i(ctx, in)
+}
+
+var _ InitializeHandler = InitializeHandlerFunc(nil)

vendor/github.com/aws/smithy-go/middleware/step_serialize.go

@@ -0,0 +1,219 @@
+package middleware
+
+import "context"
+
+// SerializeInput provides the input parameters for the SerializeMiddleware to
+// consume. SerializeMiddleware may modify the Request value before forwarding
+// SerializeInput along to the next SerializeHandler. The Parameters member
+// should not be modified by SerializeMiddleware, InitializeMiddleware should
+// be responsible for modifying the provided Parameter value.
+type SerializeInput struct {
+	Parameters interface{}
+	Request    interface{}
+}
+
+// SerializeOutput provides the result returned by the next SerializeHandler.
+type SerializeOutput struct {
+	Result interface{}
+}
+
+// SerializeHandler provides the interface for the next handler the
+// SerializeMiddleware will call in the middleware chain.
+type SerializeHandler interface {
+	HandleSerialize(ctx context.Context, in SerializeInput) (
+		out SerializeOutput, metadata Metadata, err error,
+	)
+}
+
+// SerializeMiddleware provides the interface for middleware specific to the
+// serialize step. Delegates to the next SerializeHandler for further
+// processing.
+type SerializeMiddleware interface {
+	// ID returns a unique ID for the middleware in the SerializeStep. The step does not
+	// allow duplicate IDs.
+	ID() string
+
+	// HandleSerialize invokes the middleware behavior which must delegate to the next handler
+	// for the middleware chain to continue. The method must return a result or
+	// error to its caller.
+	HandleSerialize(ctx context.Context, in SerializeInput, next SerializeHandler) (
+		out SerializeOutput, metadata Metadata, err error,
+	)
+}
+
+// SerializeMiddlewareFunc returns a SerializeMiddleware with the unique ID
+// provided, and the func to be invoked.
+func SerializeMiddlewareFunc(id string, fn func(context.Context, SerializeInput, SerializeHandler) (SerializeOutput, Metadata, error)) SerializeMiddleware {
+	return serializeMiddlewareFunc{
+		id: id,
+		fn: fn,
+	}
+}
+
+type serializeMiddlewareFunc struct {
+	// Unique ID for the middleware.
+	id string
+
+	// Middleware function to be called.
+	fn func(context.Context, SerializeInput, SerializeHandler) (
+		SerializeOutput, Metadata, error,
+	)
+}
+
+// ID returns the unique ID for the middleware.
+func (s serializeMiddlewareFunc) ID() string { return s.id }
+
+// HandleSerialize invokes the middleware Fn.
+func (s serializeMiddlewareFunc) HandleSerialize(ctx context.Context, in SerializeInput, next SerializeHandler) (
+	out SerializeOutput, metadata Metadata, err error,
+) {
+	return s.fn(ctx, in, next)
+}
+
+var _ SerializeMiddleware = (serializeMiddlewareFunc{})
+
+// SerializeStep provides the ordered grouping of SerializeMiddleware to be
+// invoked on a handler.
+type SerializeStep struct {
+	newRequest func() interface{}
+	ids        *orderedIDs
+}
+
+// NewSerializeStep returns a SerializeStep ready to have middleware for
+// initialization added to it. The newRequest func parameter is used to
+// initialize the transport specific request for the stack SerializeStep to
+// serialize the input parameters into.
+func NewSerializeStep(newRequest func() interface{}) *SerializeStep {
+	return &SerializeStep{
+		ids:        newOrderedIDs(),
+		newRequest: newRequest,
+	}
+}
+
+var _ Middleware = (*SerializeStep)(nil)
+
+// ID returns the unique ID of the step as a middleware.
+func (s *SerializeStep) ID() string {
+	return "Serialize stack step"
+}
+
+// HandleMiddleware invokes the middleware by decorating the next handler
+// provided. Returns the result of the middleware and handler being invoked.
+//
+// Implements Middleware interface.
+func (s *SerializeStep) HandleMiddleware(ctx context.Context, in interface{}, next Handler) (
+	out interface{}, metadata Metadata, err error,
+) {
+	order := s.ids.GetOrder()
+
+	var h SerializeHandler = serializeWrapHandler{Next: next}
+	for i := len(order) - 1; i >= 0; i-- {
+		h = decoratedSerializeHandler{
+			Next: h,
+			With: order[i].(SerializeMiddleware),
+		}
+	}
+
+	sIn := SerializeInput{
+		Parameters: in,
+		Request:    s.newRequest(),
+	}
+
+	res, metadata, err := h.HandleSerialize(ctx, sIn)
+	return res.Result, metadata, err
+}
+
+// Get retrieves the middleware identified by id. If the middleware is not present, returns false.
+func (s *SerializeStep) Get(id string) (SerializeMiddleware, bool) {
+	get, ok := s.ids.Get(id)
+	if !ok {
+		return nil, false
+	}
+	return get.(SerializeMiddleware), ok
+}
+
+// Add injects the middleware to the relative position of the middleware group.
+// Returns an error if the middleware already exists.
+func (s *SerializeStep) Add(m SerializeMiddleware, pos RelativePosition) error {
+	return s.ids.Add(m, pos)
+}
+
+// Insert injects the middleware relative to an existing middleware ID.
+// Returns error if the original middleware does not exist, or the middleware
+// being added already exists.
+func (s *SerializeStep) Insert(m SerializeMiddleware, relativeTo string, pos RelativePosition) error {
+	return s.ids.Insert(m, relativeTo, pos)
+}
+
+// Swap removes the middleware by id, replacing it with the new middleware.
+// Returns the middleware removed, or error if the middleware to be removed
+// doesn't exist.
+func (s *SerializeStep) Swap(id string, m SerializeMiddleware) (SerializeMiddleware, error) {
+	removed, err := s.ids.Swap(id, m)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(SerializeMiddleware), nil
+}
+
+// Remove removes the middleware by id. Returns error if the middleware
+// doesn't exist.
+func (s *SerializeStep) Remove(id string) (SerializeMiddleware, error) {
+	removed, err := s.ids.Remove(id)
+	if err != nil {
+		return nil, err
+	}
+
+	return removed.(SerializeMiddleware), nil
+}
+
+// List returns a list of the middleware in the step.
+func (s *SerializeStep) List() []string {
+	return s.ids.List()
+}
+
+// Clear removes all middleware in the step.
+func (s *SerializeStep) Clear() {
+	s.ids.Clear()
+}
+
+type serializeWrapHandler struct {
+	Next Handler
+}
+
+var _ SerializeHandler = (*serializeWrapHandler)(nil)
+
+// Implements SerializeHandler, converts types and delegates to underlying
+// generic handler.
+func (w serializeWrapHandler) HandleSerialize(ctx context.Context, in SerializeInput) (
+	out SerializeOutput, metadata Metadata, err error,
+) {
+	res, metadata, err := w.Next.Handle(ctx, in.Request)
+	return SerializeOutput{
+		Result: res,
+	}, metadata, err
+}
+
+type decoratedSerializeHandler struct {
+	Next SerializeHandler
+	With SerializeMiddleware
+}
+
+var _ SerializeHandler = (*decoratedSerializeHandler)(nil)
+
+func (h decoratedSerializeHandler) HandleSerialize(ctx context.Context, in SerializeInput) (
+	out SerializeOutput, metadata Metadata, err error,
+) {
+	return h.With.HandleSerialize(ctx, in, h.Next)
+}
+
+// SerializeHandlerFunc provides a wrapper around a function to be used as a serialize middleware handler.
+type SerializeHandlerFunc func(context.Context, SerializeInput) (SerializeOutput, Metadata, error)
+
+// HandleSerialize calls the wrapped function with the provided arguments.
+func (s SerializeHandlerFunc) HandleSerialize(ctx context.Context, in SerializeInput) (SerializeOutput, Metadata, error) {
+	return s(ctx, in)
+}
+
+var _ SerializeHandler = SerializeHandlerFunc(nil)