s3 cache client-side support

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>
2025-07-28 06:08:03 +08:00 · 2022-08-30 17:00:10 +02:00
parent 6804bcbf12
commit 57d22a7bd1
305 changed files with 45257 additions and 6 deletions
--- a/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/middleware.go
+++ b/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/middleware.go
@@ -0,0 +1,400 @@
+package v4
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	awsmiddleware "github.com/aws/aws-sdk-go-v2/aws/middleware"
+	v4Internal "github.com/aws/aws-sdk-go-v2/aws/signer/internal/v4"
+	"github.com/aws/aws-sdk-go-v2/internal/sdk"
+	"github.com/aws/smithy-go/middleware"
+	smithyhttp "github.com/aws/smithy-go/transport/http"
+)
+
+const computePayloadHashMiddlewareID = "ComputePayloadHash"
+
+// HashComputationError indicates an error occurred while computing the signing hash
+type HashComputationError struct {
+	Err error
+}
+
+// Error is the error message
+func (e *HashComputationError) Error() string {
+	return fmt.Sprintf("failed to compute payload hash: %v", e.Err)
+}
+
+// Unwrap returns the underlying error if one is set
+func (e *HashComputationError) Unwrap() error {
+	return e.Err
+}
+
+// SigningError indicates an error condition occurred while performing SigV4 signing
+type SigningError struct {
+	Err error
+}
+
+func (e *SigningError) Error() string {
+	return fmt.Sprintf("failed to sign request: %v", e.Err)
+}
+
+// Unwrap returns the underlying error cause
+func (e *SigningError) Unwrap() error {
+	return e.Err
+}
+
+// UseDynamicPayloadSigningMiddleware swaps the compute payload sha256 middleware with a resolver middleware that
+// switches between unsigned and signed payload based on TLS state for request.
+// This middleware should not be used for AWS APIs that do not support unsigned payload signing auth.
+// By default, SDK uses this middleware for known AWS APIs that support such TLS based auth selection .
+//
+// Usage example -
+// S3 PutObject API allows unsigned payload signing auth usage when TLS is enabled, and uses this middleware to
+// dynamically switch between unsigned and signed payload based on TLS state for request.
+func UseDynamicPayloadSigningMiddleware(stack *middleware.Stack) error {
+	_, err := stack.Build.Swap(computePayloadHashMiddlewareID, &dynamicPayloadSigningMiddleware{})
+	return err
+}
+
+// dynamicPayloadSigningMiddleware dynamically resolves the middleware that computes and set payload sha256 middleware.
+type dynamicPayloadSigningMiddleware struct {
+}
+
+// ID returns the resolver identifier
+func (m *dynamicPayloadSigningMiddleware) ID() string {
+	return computePayloadHashMiddlewareID
+}
+
+// HandleBuild sets a resolver that directs to the payload sha256 compute handler.
+func (m *dynamicPayloadSigningMiddleware) HandleBuild(
+	ctx context.Context, in middleware.BuildInput, next middleware.BuildHandler,
+) (
+	out middleware.BuildOutput, metadata middleware.Metadata, err error,
+) {
+	req, ok := in.Request.(*smithyhttp.Request)
+	if !ok {
+		return out, metadata, fmt.Errorf("unknown transport type %T", in.Request)
+	}
+
+	// if TLS is enabled, use unsigned payload when supported
+	if strings.EqualFold(req.URL.Scheme, "https") {
+		return (&unsignedPayload{}).HandleBuild(ctx, in, next)
+	}
+
+	// else fall back to signed payload
+	return (&computePayloadSHA256{}).HandleBuild(ctx, in, next)
+}
+
+// unsignedPayload sets the SigV4 request payload hash to unsigned.
+//
+// Will not set the Unsigned Payload magic SHA value, if a SHA has already been
+// stored in the context. (e.g. application pre-computed SHA256 before making
+// API call).
+//
+// This middleware does not check the X-Amz-Content-Sha256 header, if that
+// header is serialized a middleware must translate it into the context.
+type unsignedPayload struct{}
+
+// AddUnsignedPayloadMiddleware adds unsignedPayload to the operation
+// middleware stack
+func AddUnsignedPayloadMiddleware(stack *middleware.Stack) error {
+	return stack.Build.Add(&unsignedPayload{}, middleware.After)
+}
+
+// ID returns the unsignedPayload identifier
+func (m *unsignedPayload) ID() string {
+	return computePayloadHashMiddlewareID
+}
+
+// HandleBuild sets the payload hash to be an unsigned payload
+func (m *unsignedPayload) HandleBuild(
+	ctx context.Context, in middleware.BuildInput, next middleware.BuildHandler,
+) (
+	out middleware.BuildOutput, metadata middleware.Metadata, err error,
+) {
+	// This should not compute the content SHA256 if the value is already
+	// known. (e.g. application pre-computed SHA256 before making API call).
+	// Does not have any tight coupling to the X-Amz-Content-Sha256 header, if
+	// that header is provided a middleware must translate it into the context.
+	contentSHA := GetPayloadHash(ctx)
+	if len(contentSHA) == 0 {
+		contentSHA = v4Internal.UnsignedPayload
+	}
+
+	ctx = SetPayloadHash(ctx, contentSHA)
+	return next.HandleBuild(ctx, in)
+}
+
+// computePayloadSHA256 computes SHA256 payload hash to sign.
+//
+// Will not set the Unsigned Payload magic SHA value, if a SHA has already been
+// stored in the context. (e.g. application pre-computed SHA256 before making
+// API call).
+//
+// This middleware does not check the X-Amz-Content-Sha256 header, if that
+// header is serialized a middleware must translate it into the context.
+type computePayloadSHA256 struct{}
+
+// AddComputePayloadSHA256Middleware adds computePayloadSHA256 to the
+// operation middleware stack
+func AddComputePayloadSHA256Middleware(stack *middleware.Stack) error {
+	return stack.Build.Add(&computePayloadSHA256{}, middleware.After)
+}
+
+// RemoveComputePayloadSHA256Middleware removes computePayloadSHA256 from the
+// operation middleware stack
+func RemoveComputePayloadSHA256Middleware(stack *middleware.Stack) error {
+	_, err := stack.Build.Remove(computePayloadHashMiddlewareID)
+	return err
+}
+
+// ID is the middleware name
+func (m *computePayloadSHA256) ID() string {
+	return computePayloadHashMiddlewareID
+}
+
+// HandleBuild compute the payload hash for the request payload
+func (m *computePayloadSHA256) HandleBuild(
+	ctx context.Context, in middleware.BuildInput, next middleware.BuildHandler,
+) (
+	out middleware.BuildOutput, metadata middleware.Metadata, err error,
+) {
+	req, ok := in.Request.(*smithyhttp.Request)
+	if !ok {
+		return out, metadata, &HashComputationError{
+			Err: fmt.Errorf("unexpected request middleware type %T", in.Request),
+		}
+	}
+
+	// This should not compute the content SHA256 if the value is already
+	// known. (e.g. application pre-computed SHA256 before making API call)
+	// Does not have any tight coupling to the X-Amz-Content-Sha256 header, if
+	// that header is provided a middleware must translate it into the context.
+	if contentSHA := GetPayloadHash(ctx); len(contentSHA) != 0 {
+		return next.HandleBuild(ctx, in)
+	}
+
+	hash := sha256.New()
+	if stream := req.GetStream(); stream != nil {
+		_, err = io.Copy(hash, stream)
+		if err != nil {
+			return out, metadata, &HashComputationError{
+				Err: fmt.Errorf("failed to compute payload hash, %w", err),
+			}
+		}
+
+		if err := req.RewindStream(); err != nil {
+			return out, metadata, &HashComputationError{
+				Err: fmt.Errorf("failed to seek body to start, %w", err),
+			}
+		}
+	}
+
+	ctx = SetPayloadHash(ctx, hex.EncodeToString(hash.Sum(nil)))
+
+	return next.HandleBuild(ctx, in)
+}
+
+// SwapComputePayloadSHA256ForUnsignedPayloadMiddleware replaces the
+// ComputePayloadSHA256 middleware with the UnsignedPayload middleware.
+//
+// Use this to disable computing the Payload SHA256 checksum and instead use
+// UNSIGNED-PAYLOAD for the SHA256 value.
+func SwapComputePayloadSHA256ForUnsignedPayloadMiddleware(stack *middleware.Stack) error {
+	_, err := stack.Build.Swap(computePayloadHashMiddlewareID, &unsignedPayload{})
+	return err
+}
+
+// contentSHA256Header sets the X-Amz-Content-Sha256 header value to
+// the Payload hash stored in the context.
+type contentSHA256Header struct{}
+
+// AddContentSHA256HeaderMiddleware adds ContentSHA256Header to the
+// operation middleware stack
+func AddContentSHA256HeaderMiddleware(stack *middleware.Stack) error {
+	return stack.Build.Insert(&contentSHA256Header{}, computePayloadHashMiddlewareID, middleware.After)
+}
+
+// RemoveContentSHA256HeaderMiddleware removes contentSHA256Header middleware
+// from the operation middleware stack
+func RemoveContentSHA256HeaderMiddleware(stack *middleware.Stack) error {
+	_, err := stack.Build.Remove((*contentSHA256Header)(nil).ID())
+	return err
+}
+
+// ID returns the ContentSHA256HeaderMiddleware identifier
+func (m *contentSHA256Header) ID() string {
+	return "SigV4ContentSHA256Header"
+}
+
+// HandleBuild sets the X-Amz-Content-Sha256 header value to the Payload hash
+// stored in the context.
+func (m *contentSHA256Header) HandleBuild(
+	ctx context.Context, in middleware.BuildInput, next middleware.BuildHandler,
+) (
+	out middleware.BuildOutput, metadata middleware.Metadata, err error,
+) {
+	req, ok := in.Request.(*smithyhttp.Request)
+	if !ok {
+		return out, metadata, &HashComputationError{Err: fmt.Errorf("unexpected request middleware type %T", in.Request)}
+	}
+
+	req.Header.Set(v4Internal.ContentSHAKey, GetPayloadHash(ctx))
+
+	return next.HandleBuild(ctx, in)
+}
+
+// SignHTTPRequestMiddlewareOptions is the configuration options for the SignHTTPRequestMiddleware middleware.
+type SignHTTPRequestMiddlewareOptions struct {
+	CredentialsProvider aws.CredentialsProvider
+	Signer              HTTPSigner
+	LogSigning          bool
+}
+
+// SignHTTPRequestMiddleware is a `FinalizeMiddleware` implementation for SigV4 HTTP Signing
+type SignHTTPRequestMiddleware struct {
+	credentialsProvider aws.CredentialsProvider
+	signer              HTTPSigner
+	logSigning          bool
+}
+
+// NewSignHTTPRequestMiddleware constructs a SignHTTPRequestMiddleware using the given Signer for signing requests
+func NewSignHTTPRequestMiddleware(options SignHTTPRequestMiddlewareOptions) *SignHTTPRequestMiddleware {
+	return &SignHTTPRequestMiddleware{
+		credentialsProvider: options.CredentialsProvider,
+		signer:              options.Signer,
+		logSigning:          options.LogSigning,
+	}
+}
+
+// ID is the SignHTTPRequestMiddleware identifier
+func (s *SignHTTPRequestMiddleware) ID() string {
+	return "Signing"
+}
+
+// HandleFinalize will take the provided input and sign the request using the SigV4 authentication scheme
+func (s *SignHTTPRequestMiddleware) HandleFinalize(ctx context.Context, in middleware.FinalizeInput, next middleware.FinalizeHandler) (
+	out middleware.FinalizeOutput, metadata middleware.Metadata, err error,
+) {
+	if !haveCredentialProvider(s.credentialsProvider) {
+		return next.HandleFinalize(ctx, in)
+	}
+
+	req, ok := in.Request.(*smithyhttp.Request)
+	if !ok {
+		return out, metadata, &SigningError{Err: fmt.Errorf("unexpected request middleware type %T", in.Request)}
+	}
+
+	signingName, signingRegion := awsmiddleware.GetSigningName(ctx), awsmiddleware.GetSigningRegion(ctx)
+	payloadHash := GetPayloadHash(ctx)
+	if len(payloadHash) == 0 {
+		return out, metadata, &SigningError{Err: fmt.Errorf("computed payload hash missing from context")}
+	}
+
+	credentials, err := s.credentialsProvider.Retrieve(ctx)
+	if err != nil {
+		return out, metadata, &SigningError{Err: fmt.Errorf("failed to retrieve credentials: %w", err)}
+	}
+
+	err = s.signer.SignHTTP(ctx, credentials, req.Request, payloadHash, signingName, signingRegion, sdk.NowTime(),
+		func(o *SignerOptions) {
+			o.Logger = middleware.GetLogger(ctx)
+			o.LogSigning = s.logSigning
+		})
+	if err != nil {
+		return out, metadata, &SigningError{Err: fmt.Errorf("failed to sign http request, %w", err)}
+	}
+
+	ctx = awsmiddleware.SetSigningCredentials(ctx, credentials)
+
+	return next.HandleFinalize(ctx, in)
+}
+
+type streamingEventsPayload struct{}
+
+// AddStreamingEventsPayload adds the streamingEventsPayload middleware to the stack.
+func AddStreamingEventsPayload(stack *middleware.Stack) error {
+	return stack.Build.Add(&streamingEventsPayload{}, middleware.After)
+}
+
+func (s *streamingEventsPayload) ID() string {
+	return computePayloadHashMiddlewareID
+}
+
+func (s *streamingEventsPayload) HandleBuild(
+	ctx context.Context, in middleware.BuildInput, next middleware.BuildHandler,
+) (
+	out middleware.BuildOutput, metadata middleware.Metadata, err error,
+) {
+	contentSHA := GetPayloadHash(ctx)
+	if len(contentSHA) == 0 {
+		contentSHA = v4Internal.StreamingEventsPayload
+	}
+
+	ctx = SetPayloadHash(ctx, contentSHA)
+
+	return next.HandleBuild(ctx, in)
+}
+
+// GetSignedRequestSignature attempts to extract the signature of the request.
+// Returning an error if the request is unsigned, or unable to extract the
+// signature.
+func GetSignedRequestSignature(r *http.Request) ([]byte, error) {
+	const authHeaderSignatureElem = "Signature="
+
+	if auth := r.Header.Get(authorizationHeader); len(auth) != 0 {
+		ps := strings.Split(auth, ", ")
+		for _, p := range ps {
+			if idx := strings.Index(p, authHeaderSignatureElem); idx >= 0 {
+				sig := p[len(authHeaderSignatureElem):]
+				if len(sig) == 0 {
+					return nil, fmt.Errorf("invalid request signature authorization header")
+				}
+				return hex.DecodeString(sig)
+			}
+		}
+	}
+
+	if sig := r.URL.Query().Get("X-Amz-Signature"); len(sig) != 0 {
+		return hex.DecodeString(sig)
+	}
+
+	return nil, fmt.Errorf("request not signed")
+}
+
+func haveCredentialProvider(p aws.CredentialsProvider) bool {
+	if p == nil {
+		return false
+	}
+	switch p.(type) {
+	case aws.AnonymousCredentials,
+		*aws.AnonymousCredentials:
+		return false
+	}
+
+	return true
+}
+
+type payloadHashKey struct{}
+
+// GetPayloadHash retrieves the payload hash to use for signing
+//
+// Scoped to stack values. Use github.com/aws/smithy-go/middleware#ClearStackValues
+// to clear all stack values.
+func GetPayloadHash(ctx context.Context) (v string) {
+	v, _ = middleware.GetStackValue(ctx, payloadHashKey{}).(string)
+	return v
+}
+
+// SetPayloadHash sets the payload hash to be used for signing the request
+//
+// Scoped to stack values. Use github.com/aws/smithy-go/middleware#ClearStackValues
+// to clear all stack values.
+func SetPayloadHash(ctx context.Context, hash string) context.Context {
+	return middleware.WithStackValue(ctx, payloadHashKey{}, hash)
+}
--- a/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/presign_middleware.go
+++ b/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/presign_middleware.go
@@ -0,0 +1,127 @@
+package v4
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	awsmiddleware "github.com/aws/aws-sdk-go-v2/aws/middleware"
+	"github.com/aws/aws-sdk-go-v2/internal/sdk"
+	"github.com/aws/smithy-go/middleware"
+	smithyHTTP "github.com/aws/smithy-go/transport/http"
+)
+
+// HTTPPresigner is an interface to a SigV4 signer that can sign create a
+// presigned URL for a HTTP requests.
+type HTTPPresigner interface {
+	PresignHTTP(
+		ctx context.Context, credentials aws.Credentials, r *http.Request,
+		payloadHash string, service string, region string, signingTime time.Time,
+		optFns ...func(*SignerOptions),
+	) (url string, signedHeader http.Header, err error)
+}
+
+// PresignedHTTPRequest provides the URL and signed headers that are included
+// in the presigned URL.
+type PresignedHTTPRequest struct {
+	URL          string
+	Method       string
+	SignedHeader http.Header
+}
+
+// PresignHTTPRequestMiddlewareOptions is the options for the PresignHTTPRequestMiddleware middleware.
+type PresignHTTPRequestMiddlewareOptions struct {
+	CredentialsProvider aws.CredentialsProvider
+	Presigner           HTTPPresigner
+	LogSigning          bool
+}
+
+// PresignHTTPRequestMiddleware provides the Finalize middleware for creating a
+// presigned URL for an HTTP request.
+//
+// Will short circuit the middleware stack and not forward onto the next
+// Finalize handler.
+type PresignHTTPRequestMiddleware struct {
+	credentialsProvider aws.CredentialsProvider
+	presigner           HTTPPresigner
+	logSigning          bool
+}
+
+// NewPresignHTTPRequestMiddleware returns a new PresignHTTPRequestMiddleware
+// initialized with the presigner.
+func NewPresignHTTPRequestMiddleware(options PresignHTTPRequestMiddlewareOptions) *PresignHTTPRequestMiddleware {
+	return &PresignHTTPRequestMiddleware{
+		credentialsProvider: options.CredentialsProvider,
+		presigner:           options.Presigner,
+		logSigning:          options.LogSigning,
+	}
+}
+
+// ID provides the middleware ID.
+func (*PresignHTTPRequestMiddleware) ID() string { return "PresignHTTPRequest" }
+
+// HandleFinalize will take the provided input and create a presigned url for
+// the http request using the SigV4 presign authentication scheme.
+//
+// Since the signed request is not a valid HTTP request
+func (s *PresignHTTPRequestMiddleware) HandleFinalize(
+	ctx context.Context, in middleware.FinalizeInput, next middleware.FinalizeHandler,
+) (
+	out middleware.FinalizeOutput, metadata middleware.Metadata, err error,
+) {
+	req, ok := in.Request.(*smithyHTTP.Request)
+	if !ok {
+		return out, metadata, &SigningError{
+			Err: fmt.Errorf("unexpected request middleware type %T", in.Request),
+		}
+	}
+
+	httpReq := req.Build(ctx)
+	if !haveCredentialProvider(s.credentialsProvider) {
+		out.Result = &PresignedHTTPRequest{
+			URL:          httpReq.URL.String(),
+			Method:       httpReq.Method,
+			SignedHeader: http.Header{},
+		}
+
+		return out, metadata, nil
+	}
+
+	signingName := awsmiddleware.GetSigningName(ctx)
+	signingRegion := awsmiddleware.GetSigningRegion(ctx)
+	payloadHash := GetPayloadHash(ctx)
+	if len(payloadHash) == 0 {
+		return out, metadata, &SigningError{
+			Err: fmt.Errorf("computed payload hash missing from context"),
+		}
+	}
+
+	credentials, err := s.credentialsProvider.Retrieve(ctx)
+	if err != nil {
+		return out, metadata, &SigningError{
+			Err: fmt.Errorf("failed to retrieve credentials: %w", err),
+		}
+	}
+
+	u, h, err := s.presigner.PresignHTTP(ctx, credentials,
+		httpReq, payloadHash, signingName, signingRegion, sdk.NowTime(),
+		func(o *SignerOptions) {
+			o.Logger = middleware.GetLogger(ctx)
+			o.LogSigning = s.logSigning
+		})
+	if err != nil {
+		return out, metadata, &SigningError{
+			Err: fmt.Errorf("failed to sign http request, %w", err),
+		}
+	}
+
+	out.Result = &PresignedHTTPRequest{
+		URL:          u,
+		Method:       httpReq.Method,
+		SignedHeader: h,
+	}
+
+	return out, metadata, nil
+}
--- a/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/stream.go
+++ b/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/stream.go
@@ -0,0 +1,86 @@
+package v4
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"github.com/aws/aws-sdk-go-v2/aws"
+	v4Internal "github.com/aws/aws-sdk-go-v2/aws/signer/internal/v4"
+	"strings"
+	"time"
+)
+
+// EventStreamSigner is an AWS EventStream protocol signer.
+type EventStreamSigner interface {
+	GetSignature(ctx context.Context, headers, payload []byte, signingTime time.Time, optFns ...func(*StreamSignerOptions)) ([]byte, error)
+}
+
+// StreamSignerOptions is the configuration options for StreamSigner.
+type StreamSignerOptions struct{}
+
+// StreamSigner implements Signature Version 4 (SigV4) signing of event stream encoded payloads.
+type StreamSigner struct {
+	options StreamSignerOptions
+
+	credentials aws.Credentials
+	service     string
+	region      string
+
+	prevSignature []byte
+
+	signingKeyDeriver *v4Internal.SigningKeyDeriver
+}
+
+// NewStreamSigner returns a new AWS EventStream protocol signer.
+func NewStreamSigner(credentials aws.Credentials, service, region string, seedSignature []byte, optFns ...func(*StreamSignerOptions)) *StreamSigner {
+	o := StreamSignerOptions{}
+
+	for _, fn := range optFns {
+		fn(&o)
+	}
+
+	return &StreamSigner{
+		options:           o,
+		credentials:       credentials,
+		service:           service,
+		region:            region,
+		signingKeyDeriver: v4Internal.NewSigningKeyDeriver(),
+		prevSignature:     seedSignature,
+	}
+}
+
+// GetSignature signs the provided header and payload bytes.
+func (s *StreamSigner) GetSignature(ctx context.Context, headers, payload []byte, signingTime time.Time, optFns ...func(*StreamSignerOptions)) ([]byte, error) {
+	options := s.options
+
+	for _, fn := range optFns {
+		fn(&options)
+	}
+
+	prevSignature := s.prevSignature
+
+	st := v4Internal.NewSigningTime(signingTime)
+
+	sigKey := s.signingKeyDeriver.DeriveKey(s.credentials, s.service, s.region, st)
+
+	scope := v4Internal.BuildCredentialScope(st, s.region, s.service)
+
+	stringToSign := s.buildEventStreamStringToSign(headers, payload, prevSignature, scope, &st)
+
+	signature := v4Internal.HMACSHA256(sigKey, []byte(stringToSign))
+	s.prevSignature = signature
+
+	return signature, nil
+}
+
+func (s *StreamSigner) buildEventStreamStringToSign(headers, payload, previousSignature []byte, credentialScope string, signingTime *v4Internal.SigningTime) string {
+	hash := sha256.New()
+	return strings.Join([]string{
+		"AWS4-HMAC-SHA256-PAYLOAD",
+		signingTime.TimeFormat(),
+		credentialScope,
+		hex.EncodeToString(previousSignature),
+		hex.EncodeToString(makeHash(hash, headers)),
+		hex.EncodeToString(makeHash(hash, payload)),
+	}, "\n")
+}
--- a/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/v4.go
+++ b/vendor/github.com/aws/aws-sdk-go-v2/aws/signer/v4/v4.go
@@ -0,0 +1,542 @@
+// Package v4 implements signing for AWS V4 signer
+//
+// Provides request signing for request that need to be signed with
+// AWS V4 Signatures.
+//
+// Standalone Signer
+//
+// Generally using the signer outside of the SDK should not require any additional
+//  The signer does this by taking advantage of the URL.EscapedPath method. If your request URI requires
+// additional escaping you many need to use the URL.Opaque to define what the raw URI should be sent
+// to the service as.
+//
+// The signer will first check the URL.Opaque field, and use its value if set.
+// The signer does require the URL.Opaque field to be set in the form of:
+//
+//     "//<hostname>/<path>"
+//
+//     // e.g.
+//     "//example.com/some/path"
+//
+// The leading "//" and hostname are required or the URL.Opaque escaping will
+// not work correctly.
+//
+// If URL.Opaque is not set the signer will fallback to the URL.EscapedPath()
+// method and using the returned value.
+//
+// AWS v4 signature validation requires that the canonical string's URI path
+// element must be the URI escaped form of the HTTP request's path.
+// http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
+//
+// The Go HTTP client will perform escaping automatically on the request. Some
+// of these escaping may cause signature validation errors because the HTTP
+// request differs from the URI path or query that the signature was generated.
+// https://golang.org/pkg/net/url/#URL.EscapedPath
+//
+// Because of this, it is recommended that when using the signer outside of the
+// SDK that explicitly escaping the request prior to being signed is preferable,
+// and will help prevent signature validation errors. This can be done by setting
+// the URL.Opaque or URL.RawPath. The SDK will use URL.Opaque first and then
+// call URL.EscapedPath() if Opaque is not set.
+//
+// Test `TestStandaloneSign` provides a complete example of using the signer
+// outside of the SDK and pre-escaping the URI path.
+package v4
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"net/http"
+	"net/textproto"
+	"net/url"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	v4Internal "github.com/aws/aws-sdk-go-v2/aws/signer/internal/v4"
+	"github.com/aws/smithy-go/encoding/httpbinding"
+	"github.com/aws/smithy-go/logging"
+)
+
+const (
+	signingAlgorithm    = "AWS4-HMAC-SHA256"
+	authorizationHeader = "Authorization"
+)
+
+// HTTPSigner is an interface to a SigV4 signer that can sign HTTP requests
+type HTTPSigner interface {
+	SignHTTP(ctx context.Context, credentials aws.Credentials, r *http.Request, payloadHash string, service string, region string, signingTime time.Time, optFns ...func(*SignerOptions)) error
+}
+
+type keyDerivator interface {
+	DeriveKey(credential aws.Credentials, service, region string, signingTime v4Internal.SigningTime) []byte
+}
+
+// SignerOptions is the SigV4 Signer options.
+type SignerOptions struct {
+	// Disables the Signer's moving HTTP header key/value pairs from the HTTP
+	// request header to the request's query string. This is most commonly used
+	// with pre-signed requests preventing headers from being added to the
+	// request's query string.
+	DisableHeaderHoisting bool
+
+	// Disables the automatic escaping of the URI path of the request for the
+	// siganture's canonical string's path. For services that do not need additional
+	// escaping then use this to disable the signer escaping the path.
+	//
+	// S3 is an example of a service that does not need additional escaping.
+	//
+	// http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
+	DisableURIPathEscaping bool
+
+	// The logger to send log messages to.
+	Logger logging.Logger
+
+	// Enable logging of signed requests.
+	// This will enable logging of the canonical request, the string to sign, and for presigning the subsequent
+	// presigned URL.
+	LogSigning bool
+}
+
+// Signer applies AWS v4 signing to given request. Use this to sign requests
+// that need to be signed with AWS V4 Signatures.
+type Signer struct {
+	options      SignerOptions
+	keyDerivator keyDerivator
+}
+
+// NewSigner returns a new SigV4 Signer
+func NewSigner(optFns ...func(signer *SignerOptions)) *Signer {
+	options := SignerOptions{}
+
+	for _, fn := range optFns {
+		fn(&options)
+	}
+
+	return &Signer{options: options, keyDerivator: v4Internal.NewSigningKeyDeriver()}
+}
+
+type httpSigner struct {
+	Request      *http.Request
+	ServiceName  string
+	Region       string
+	Time         v4Internal.SigningTime
+	Credentials  aws.Credentials
+	KeyDerivator keyDerivator
+	IsPreSign    bool
+
+	PayloadHash string
+
+	DisableHeaderHoisting  bool
+	DisableURIPathEscaping bool
+}
+
+func (s *httpSigner) Build() (signedRequest, error) {
+	req := s.Request
+
+	query := req.URL.Query()
+	headers := req.Header
+
+	s.setRequiredSigningFields(headers, query)
+
+	// Sort Each Query Key's Values
+	for key := range query {
+		sort.Strings(query[key])
+	}
+
+	v4Internal.SanitizeHostForHeader(req)
+
+	credentialScope := s.buildCredentialScope()
+	credentialStr := s.Credentials.AccessKeyID + "/" + credentialScope
+	if s.IsPreSign {
+		query.Set(v4Internal.AmzCredentialKey, credentialStr)
+	}
+
+	unsignedHeaders := headers
+	if s.IsPreSign && !s.DisableHeaderHoisting {
+		var urlValues url.Values
+		urlValues, unsignedHeaders = buildQuery(v4Internal.AllowedQueryHoisting, headers)
+		for k := range urlValues {
+			query[k] = urlValues[k]
+		}
+	}
+
+	host := req.URL.Host
+	if len(req.Host) > 0 {
+		host = req.Host
+	}
+
+	signedHeaders, signedHeadersStr, canonicalHeaderStr := s.buildCanonicalHeaders(host, v4Internal.IgnoredHeaders, unsignedHeaders, s.Request.ContentLength)
+
+	if s.IsPreSign {
+		query.Set(v4Internal.AmzSignedHeadersKey, signedHeadersStr)
+	}
+
+	var rawQuery strings.Builder
+	rawQuery.WriteString(strings.Replace(query.Encode(), "+", "%20", -1))
+
+	canonicalURI := v4Internal.GetURIPath(req.URL)
+	if !s.DisableURIPathEscaping {
+		canonicalURI = httpbinding.EscapePath(canonicalURI, false)
+	}
+
+	canonicalString := s.buildCanonicalString(
+		req.Method,
+		canonicalURI,
+		rawQuery.String(),
+		signedHeadersStr,
+		canonicalHeaderStr,
+	)
+
+	strToSign := s.buildStringToSign(credentialScope, canonicalString)
+	signingSignature, err := s.buildSignature(strToSign)
+	if err != nil {
+		return signedRequest{}, err
+	}
+
+	if s.IsPreSign {
+		rawQuery.WriteString("&X-Amz-Signature=")
+		rawQuery.WriteString(signingSignature)
+	} else {
+		headers[authorizationHeader] = append(headers[authorizationHeader][:0], buildAuthorizationHeader(credentialStr, signedHeadersStr, signingSignature))
+	}
+
+	req.URL.RawQuery = rawQuery.String()
+
+	return signedRequest{
+		Request:         req,
+		SignedHeaders:   signedHeaders,
+		CanonicalString: canonicalString,
+		StringToSign:    strToSign,
+		PreSigned:       s.IsPreSign,
+	}, nil
+}
+
+func buildAuthorizationHeader(credentialStr, signedHeadersStr, signingSignature string) string {
+	const credential = "Credential="
+	const signedHeaders = "SignedHeaders="
+	const signature = "Signature="
+	const commaSpace = ", "
+
+	var parts strings.Builder
+	parts.Grow(len(signingAlgorithm) + 1 +
+		len(credential) + len(credentialStr) + 2 +
+		len(signedHeaders) + len(signedHeadersStr) + 2 +
+		len(signature) + len(signingSignature),
+	)
+	parts.WriteString(signingAlgorithm)
+	parts.WriteRune(' ')
+	parts.WriteString(credential)
+	parts.WriteString(credentialStr)
+	parts.WriteString(commaSpace)
+	parts.WriteString(signedHeaders)
+	parts.WriteString(signedHeadersStr)
+	parts.WriteString(commaSpace)
+	parts.WriteString(signature)
+	parts.WriteString(signingSignature)
+	return parts.String()
+}
+
+// SignHTTP signs AWS v4 requests with the provided payload hash, service name, region the
+// request is made to, and time the request is signed at. The signTime allows
+// you to specify that a request is signed for the future, and cannot be
+// used until then.
+//
+// The payloadHash is the hex encoded SHA-256 hash of the request payload, and
+// must be provided. Even if the request has no payload (aka body). If the
+// request has no payload you should use the hex encoded SHA-256 of an empty
+// string as the payloadHash value.
+//
+//   "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+//
+// Some services such as Amazon S3 accept alternative values for the payload
+// hash, such as "UNSIGNED-PAYLOAD" for requests where the body will not be
+// included in the request signature.
+//
+// https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-header-based-auth.html
+//
+// Sign differs from Presign in that it will sign the request using HTTP
+// header values. This type of signing is intended for http.Request values that
+// will not be shared, or are shared in a way the header values on the request
+// will not be lost.
+//
+// The passed in request will be modified in place.
+func (s Signer) SignHTTP(ctx context.Context, credentials aws.Credentials, r *http.Request, payloadHash string, service string, region string, signingTime time.Time, optFns ...func(options *SignerOptions)) error {
+	options := s.options
+
+	for _, fn := range optFns {
+		fn(&options)
+	}
+
+	signer := &httpSigner{
+		Request:                r,
+		PayloadHash:            payloadHash,
+		ServiceName:            service,
+		Region:                 region,
+		Credentials:            credentials,
+		Time:                   v4Internal.NewSigningTime(signingTime.UTC()),
+		DisableHeaderHoisting:  options.DisableHeaderHoisting,
+		DisableURIPathEscaping: options.DisableURIPathEscaping,
+		KeyDerivator:           s.keyDerivator,
+	}
+
+	signedRequest, err := signer.Build()
+	if err != nil {
+		return err
+	}
+
+	logSigningInfo(ctx, options, &signedRequest, false)
+
+	return nil
+}
+
+// PresignHTTP signs AWS v4 requests with the payload hash, service name, region
+// the request is made to, and time the request is signed at. The signTime
+// allows you to specify that a request is signed for the future, and cannot
+// be used until then.
+//
+// Returns the signed URL and the map of HTTP headers that were included in the
+// signature or an error if signing the request failed. For presigned requests
+// these headers and their values must be included on the HTTP request when it
+// is made. This is helpful to know what header values need to be shared with
+// the party the presigned request will be distributed to.
+//
+// The payloadHash is the hex encoded SHA-256 hash of the request payload, and
+// must be provided. Even if the request has no payload (aka body). If the
+// request has no payload you should use the hex encoded SHA-256 of an empty
+// string as the payloadHash value.
+//
+//   "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+//
+// Some services such as Amazon S3 accept alternative values for the payload
+// hash, such as "UNSIGNED-PAYLOAD" for requests where the body will not be
+// included in the request signature.
+//
+// https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-header-based-auth.html
+//
+// PresignHTTP differs from SignHTTP in that it will sign the request using
+// query string instead of header values. This allows you to share the
+// Presigned Request's URL with third parties, or distribute it throughout your
+// system with minimal dependencies.
+//
+// PresignHTTP will not set the expires time of the presigned request
+// automatically. To specify the expire duration for a request add the
+// "X-Amz-Expires" query parameter on the request with the value as the
+// duration in seconds the presigned URL should be considered valid for. This
+// parameter is not used by all AWS services, and is most notable used by
+// Amazon S3 APIs.
+//
+//   expires := 20 * time.Minute
+//   query := req.URL.Query()
+//   query.Set("X-Amz-Expires", strconv.FormatInt(int64(expires/time.Second), 10)
+//   req.URL.RawQuery = query.Encode()
+//
+// This method does not modify the provided request.
+func (s *Signer) PresignHTTP(
+	ctx context.Context, credentials aws.Credentials, r *http.Request,
+	payloadHash string, service string, region string, signingTime time.Time,
+	optFns ...func(*SignerOptions),
+) (signedURI string, signedHeaders http.Header, err error) {
+	options := s.options
+
+	for _, fn := range optFns {
+		fn(&options)
+	}
+
+	signer := &httpSigner{
+		Request:                r.Clone(r.Context()),
+		PayloadHash:            payloadHash,
+		ServiceName:            service,
+		Region:                 region,
+		Credentials:            credentials,
+		Time:                   v4Internal.NewSigningTime(signingTime.UTC()),
+		IsPreSign:              true,
+		DisableHeaderHoisting:  options.DisableHeaderHoisting,
+		DisableURIPathEscaping: options.DisableURIPathEscaping,
+		KeyDerivator:           s.keyDerivator,
+	}
+
+	signedRequest, err := signer.Build()
+	if err != nil {
+		return "", nil, err
+	}
+
+	logSigningInfo(ctx, options, &signedRequest, true)
+
+	signedHeaders = make(http.Header)
+
+	// For the signed headers we canonicalize the header keys in the returned map.
+	// This avoids situations where can standard library double headers like host header. For example the standard
+	// library will set the Host header, even if it is present in lower-case form.
+	for k, v := range signedRequest.SignedHeaders {
+		key := textproto.CanonicalMIMEHeaderKey(k)
+		signedHeaders[key] = append(signedHeaders[key], v...)
+	}
+
+	return signedRequest.Request.URL.String(), signedHeaders, nil
+}
+
+func (s *httpSigner) buildCredentialScope() string {
+	return v4Internal.BuildCredentialScope(s.Time, s.Region, s.ServiceName)
+}
+
+func buildQuery(r v4Internal.Rule, header http.Header) (url.Values, http.Header) {
+	query := url.Values{}
+	unsignedHeaders := http.Header{}
+	for k, h := range header {
+		if r.IsValid(k) {
+			query[k] = h
+		} else {
+			unsignedHeaders[k] = h
+		}
+	}
+
+	return query, unsignedHeaders
+}
+
+func (s *httpSigner) buildCanonicalHeaders(host string, rule v4Internal.Rule, header http.Header, length int64) (signed http.Header, signedHeaders, canonicalHeadersStr string) {
+	signed = make(http.Header)
+
+	var headers []string
+	const hostHeader = "host"
+	headers = append(headers, hostHeader)
+	signed[hostHeader] = append(signed[hostHeader], host)
+
+	if length > 0 {
+		const contentLengthHeader = "content-length"
+		headers = append(headers, contentLengthHeader)
+		signed[contentLengthHeader] = append(signed[contentLengthHeader], strconv.FormatInt(length, 10))
+	}
+
+	for k, v := range header {
+		if !rule.IsValid(k) {
+			continue // ignored header
+		}
+
+		lowerCaseKey := strings.ToLower(k)
+		if _, ok := signed[lowerCaseKey]; ok {
+			// include additional values
+			signed[lowerCaseKey] = append(signed[lowerCaseKey], v...)
+			continue
+		}
+
+		headers = append(headers, lowerCaseKey)
+		signed[lowerCaseKey] = v
+	}
+	sort.Strings(headers)
+
+	signedHeaders = strings.Join(headers, ";")
+
+	var canonicalHeaders strings.Builder
+	n := len(headers)
+	const colon = ':'
+	for i := 0; i < n; i++ {
+		if headers[i] == hostHeader {
+			canonicalHeaders.WriteString(hostHeader)
+			canonicalHeaders.WriteRune(colon)
+			canonicalHeaders.WriteString(v4Internal.StripExcessSpaces(host))
+		} else {
+			canonicalHeaders.WriteString(headers[i])
+			canonicalHeaders.WriteRune(colon)
+			// Trim out leading, trailing, and dedup inner spaces from signed header values.
+			values := signed[headers[i]]
+			for j, v := range values {
+				cleanedValue := strings.TrimSpace(v4Internal.StripExcessSpaces(v))
+				canonicalHeaders.WriteString(cleanedValue)
+				if j < len(values)-1 {
+					canonicalHeaders.WriteRune(',')
+				}
+			}
+		}
+		canonicalHeaders.WriteRune('\n')
+	}
+	canonicalHeadersStr = canonicalHeaders.String()
+
+	return signed, signedHeaders, canonicalHeadersStr
+}
+
+func (s *httpSigner) buildCanonicalString(method, uri, query, signedHeaders, canonicalHeaders string) string {
+	return strings.Join([]string{
+		method,
+		uri,
+		query,
+		canonicalHeaders,
+		signedHeaders,
+		s.PayloadHash,
+	}, "\n")
+}
+
+func (s *httpSigner) buildStringToSign(credentialScope, canonicalRequestString string) string {
+	return strings.Join([]string{
+		signingAlgorithm,
+		s.Time.TimeFormat(),
+		credentialScope,
+		hex.EncodeToString(makeHash(sha256.New(), []byte(canonicalRequestString))),
+	}, "\n")
+}
+
+func makeHash(hash hash.Hash, b []byte) []byte {
+	hash.Reset()
+	hash.Write(b)
+	return hash.Sum(nil)
+}
+
+func (s *httpSigner) buildSignature(strToSign string) (string, error) {
+	key := s.KeyDerivator.DeriveKey(s.Credentials, s.ServiceName, s.Region, s.Time)
+	return hex.EncodeToString(v4Internal.HMACSHA256(key, []byte(strToSign))), nil
+}
+
+func (s *httpSigner) setRequiredSigningFields(headers http.Header, query url.Values) {
+	amzDate := s.Time.TimeFormat()
+
+	if s.IsPreSign {
+		query.Set(v4Internal.AmzAlgorithmKey, signingAlgorithm)
+		if sessionToken := s.Credentials.SessionToken; len(sessionToken) > 0 {
+			query.Set("X-Amz-Security-Token", sessionToken)
+		}
+
+		query.Set(v4Internal.AmzDateKey, amzDate)
+		return
+	}
+
+	headers[v4Internal.AmzDateKey] = append(headers[v4Internal.AmzDateKey][:0], amzDate)
+
+	if len(s.Credentials.SessionToken) > 0 {
+		headers[v4Internal.AmzSecurityTokenKey] = append(headers[v4Internal.AmzSecurityTokenKey][:0], s.Credentials.SessionToken)
+	}
+}
+
+func logSigningInfo(ctx context.Context, options SignerOptions, request *signedRequest, isPresign bool) {
+	if !options.LogSigning {
+		return
+	}
+	signedURLMsg := ""
+	if isPresign {
+		signedURLMsg = fmt.Sprintf(logSignedURLMsg, request.Request.URL.String())
+	}
+	logger := logging.WithContext(ctx, options.Logger)
+	logger.Logf(logging.Debug, logSignInfoMsg, request.CanonicalString, request.StringToSign, signedURLMsg)
+}
+
+type signedRequest struct {
+	Request         *http.Request
+	SignedHeaders   http.Header
+	CanonicalString string
+	StringToSign    string
+	PreSigned       bool
+}
+
+const logSignInfoMsg = `Request Signature:
+---[ CANONICAL STRING  ]-----------------------------
+%s
+---[ STRING TO SIGN ]--------------------------------
+%s%s
+-----------------------------------------------------`
+const logSignedURLMsg = `
+---[ SIGNED URL ]------------------------------------
+%s`