如何将 AWS 区块链服务与 go-ethereum 一起使用？

Question

AWS 区块链服务为HTTP和WebSocket协议提供端点，但需要 IAM 签名验证才能使用它们。要使用 HTTP 端点，我只需通过 AWS SDK在http.RoundTripper接口中对其进行签名。但是，如果我需要使用WebSocket端点，由于go-ethereum的限制，我只能通过rpc.DialWebsocketWithDialer传入一个websocket.Dialer结构，这意味着我无法通过实现接口来解决这个问题。如何将 AWS 区块链服务的 WebSocket 端点与 go-ethereum 结合使用？

Answer 1

通过阅读github.com/gorilla/websocket 的源代码，我发现函数中有一个逻辑(*Dialer) DialContext将 http.Request 指针传递给可定制的函数，这意味着我可以编写一个与forProxy做同样事情的函数http.RoundTripper注入标头。

WebSocket

package transport

import (

    "context"

    "crypto/sha256"

    "encoding/hex"

    "net/http"

    "net/url"

    "time"

    "github.com/aws/aws-sdk-go-v2/aws"

    "github.com/aws/aws-sdk-go-v2/aws/signer/v4"

    "github.com/gorilla/websocket"

)

func NewWebSocketDialer(config aws.Config) (*websocket.Dialer, error) {

    return &websocket.Dialer{

        HandshakeTimeout: 45 * time.Second,

        Proxy: func(request *http.Request) (*url.URL, error) {

            credentials, err := config.Credentials.Retrieve(request.Context())

            if err != nil {

                return nil, err

            }

            // Because AWS may sign some unrelated headers and cause authentication failure, you need to create a blank request.

            internalRequest, err := http.NewRequest(http.MethodGet, request.URL.String(), nil)

            if err != nil {

                return nil, err

            }

            header := request.Header.Clone()

            hash := sha256.New()

            signer := v4.NewSigner()

            if err := signer.SignHTTP(context.Background(), credentials, internalRequest, hex.EncodeToString(hash.Sum(nil)), "managedblockchain", config.Region, time.Now()); err != nil {

                return nil, err

            }

            request.Header = internalRequest.Header

            request.Header.Set("Connection", header["Connection"][0])

            request.Header.Set("Sec-WebSocket-Key", header["Sec-WebSocket-Key"][0])

            request.Header.Set("Sec-WebSocket-Version", header["Sec-WebSocket-Version"][0])

            request.Header.Set("Upgrade", header["Upgrade"][0])

            return http.ProxyFromEnvironment(request)

        },

    }, nil

}

HTTP

package transport

import (

    "compress/gzip"

    "context"

    "crypto/sha256"

    "encoding/base64"

    "encoding/hex"

    "io"

    "net/http"

    "time"

    "github.com/aws/aws-sdk-go-v2/aws"

    "github.com/aws/aws-sdk-go-v2/aws/signer/v4"

)

var _ http.RoundTripper = &httpRoundTripper{}

type httpRoundTripper struct {

    config aws.Config

}

func (h httpRoundTripper) RoundTrip(request *http.Request) (*http.Response, error) {

    credentials, err := h.config.Credentials.Retrieve(request.Context())

    if err != nil {

        return nil, err

    }

    internalRequest := request.Clone(request.Context())

    bodyReader, err := request.GetBody()

    if err != nil {

        return nil, err

    }

    hash := sha256.New()

    if _, err := io.Copy(hash, bodyReader); err != nil {

        return nil, err

    }

    signer := v4.NewSigner()

    if err := signer.SignHTTP(context.Background(), credentials, internalRequest, hex.EncodeToString(hash.Sum(nil)), "managedblockchain", h.config.Region, time.Now()); err != nil {

        return nil, err

    }

    response, err := h.config.HTTPClient.Do(internalRequest)

    if err != nil {

        return nil, err

    }

    if response.Header.Get("Content-Type") == "gzip" {

        gzipReader, err := gzip.NewReader(base64.NewDecoder(base64.StdEncoding, response.Body))

        if err != nil {

            return nil, err

        }

        request.Header.Set("Content-Type", "application/json")

        response.Body = gzipReader

    }

    return response, nil

}

func NewHttpRoundTripper(cfg aws.Config) http.RoundTripper {

    return httpRoundTripper{

        config: cfg,

    }

}