Set Auth Differently In Our Powchain Constructor (#10501)

network/auth.go

@@ -0,0 +1,47 @@
+package network
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/golang-jwt/jwt/v4"
+	"github.com/pkg/errors"
+)
+
+// DefaultRPCHTTPTimeout for HTTP requests via an RPC connection to an execution node.
+const DefaultRPCHTTPTimeout = time.Second * 6
+
+// This creates a custom HTTP transport which we can attach to our HTTP client
+// in order to inject JWT auth strings into our HTTP request headers. Authentication
+// is required when interacting with an Ethereum engine API server via HTTP, and JWT
+// is chosen as the scheme of choice.
+// For more details on the requirements of authentication when using the engine API, see
+// the specification here: https://github.com/ethereum/execution-apis/blob/main/src/engine/authentication.md
+//
+// To use this transport, initialize a new &http.Client{} from the standard library
+// and set the Transport field to &jwtTransport{} with values
+// http.DefaultTransport and a JWT secret.
+type jwtTransport struct {
+	underlyingTransport http.RoundTripper
+	jwtSecret           []byte
+}
+
+// RoundTrip ensures our transport implements http.RoundTripper interface from the
+// standard library. When used as the transport for an HTTP client, the code below
+// will run every time our client makes an HTTP request. This is used to inject
+// an JWT bearer token in the Authorization request header of every outgoing request
+// our HTTP client makes.
+func (t *jwtTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
+		// Required claim for engine API auth. "iat" stands for issued at
+		// and it must be a unix timestamp that is +/- 5 seconds from the current
+		// timestamp at the moment the server verifies this value.
+		"iat": time.Now().Unix(),
+	})
+	tokenString, err := token.SignedString(t.jwtSecret)
+	if err != nil {
+		return nil, errors.Wrap(err, "could not produce signed JWT token")
+	}
+	req.Header.Set("Authorization", "Bearer "+tokenString)
+	return t.underlyingTransport.RoundTrip(req)
+}