111 lines
3.9 KiB
Go
111 lines
3.9 KiB
Go
package presignedurl
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import (
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"context"
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"fmt"
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awsmiddleware "github.com/aws/aws-sdk-go-v2/aws/middleware"
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v4 "github.com/aws/aws-sdk-go-v2/aws/signer/v4"
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"github.com/aws/smithy-go/middleware"
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)
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// URLPresigner provides the interface to presign the input parameters in to a
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// presigned URL.
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type URLPresigner interface {
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// PresignURL presigns a URL.
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PresignURL(ctx context.Context, srcRegion string, params interface{}) (*v4.PresignedHTTPRequest, error)
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}
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// ParameterAccessor provides an collection of accessor to for retrieving and
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// setting the values needed to PresignedURL generation
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type ParameterAccessor struct {
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// GetPresignedURL accessor points to a function that retrieves a presigned url if present
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GetPresignedURL func(interface{}) (string, bool, error)
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// GetSourceRegion accessor points to a function that retrieves source region for presigned url
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GetSourceRegion func(interface{}) (string, bool, error)
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// CopyInput accessor points to a function that takes in an input, and returns a copy.
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CopyInput func(interface{}) (interface{}, error)
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// SetDestinationRegion accessor points to a function that sets destination region on api input struct
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SetDestinationRegion func(interface{}, string) error
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// SetPresignedURL accessor points to a function that sets presigned url on api input struct
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SetPresignedURL func(interface{}, string) error
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}
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// Options provides the set of options needed by the presigned URL middleware.
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type Options struct {
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// Accessor are the parameter accessors used by this middleware
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Accessor ParameterAccessor
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// Presigner is the URLPresigner used by the middleware
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Presigner URLPresigner
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}
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// AddMiddleware adds the Presign URL middleware to the middleware stack.
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func AddMiddleware(stack *middleware.Stack, opts Options) error {
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return stack.Initialize.Add(&presign{options: opts}, middleware.Before)
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}
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// RemoveMiddleware removes the Presign URL middleware from the stack.
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func RemoveMiddleware(stack *middleware.Stack) error {
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_, err := stack.Initialize.Remove((*presign)(nil).ID())
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return err
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}
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type presign struct {
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options Options
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}
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func (m *presign) ID() string { return "Presign" }
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func (m *presign) HandleInitialize(
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ctx context.Context, input middleware.InitializeInput, next middleware.InitializeHandler,
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) (
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out middleware.InitializeOutput, metadata middleware.Metadata, err error,
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) {
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// If PresignedURL is already set ignore middleware.
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if _, ok, err := m.options.Accessor.GetPresignedURL(input.Parameters); err != nil {
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return out, metadata, fmt.Errorf("presign middleware failed, %w", err)
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} else if ok {
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return next.HandleInitialize(ctx, input)
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}
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// If have source region is not set ignore middleware.
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srcRegion, ok, err := m.options.Accessor.GetSourceRegion(input.Parameters)
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if err != nil {
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return out, metadata, fmt.Errorf("presign middleware failed, %w", err)
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} else if !ok || len(srcRegion) == 0 {
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return next.HandleInitialize(ctx, input)
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}
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// Create a copy of the original input so the destination region value can
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// be added. This ensures that value does not leak into the original
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// request parameters.
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paramCpy, err := m.options.Accessor.CopyInput(input.Parameters)
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if err != nil {
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return out, metadata, fmt.Errorf("unable to create presigned URL, %w", err)
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}
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// Destination region is the API client's configured region.
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dstRegion := awsmiddleware.GetRegion(ctx)
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if err = m.options.Accessor.SetDestinationRegion(paramCpy, dstRegion); err != nil {
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return out, metadata, fmt.Errorf("presign middleware failed, %w", err)
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}
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presignedReq, err := m.options.Presigner.PresignURL(ctx, srcRegion, paramCpy)
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if err != nil {
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return out, metadata, fmt.Errorf("unable to create presigned URL, %w", err)
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}
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// Update the original input with the presigned URL value.
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if err = m.options.Accessor.SetPresignedURL(input.Parameters, presignedReq.URL); err != nil {
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return out, metadata, fmt.Errorf("presign middleware failed, %w", err)
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}
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return next.HandleInitialize(ctx, input)
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}
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