feat(transports): add retries to HTTP transport

Cargo.toml

@@ -28,6 +28,7 @@ serde = { version = "1.0.90", features = ["derive"] }
 serde_json = "1.0.39"
 tiny-keccak = { version = "2.0.1", features = ["keccak"] }
 pin-project = "1.0"
+chrono = "0.4.31"
 # Optional deps
 secp256k1 = { version = "0.29", features = ["recovery"], optional = true }
 once_cell = { version = "1.8.0", optional = true }

src/error.rs

@@ -16,6 +16,20 @@ pub enum TransportError {
     /// Arbitrary, developer-readable description of the occurred error.
     #[display(fmt = "{}", _0)]
     Message(String),
+    /// Recoverable rate limit error.
+    #[display(fmt = "rate limit: {}", _0)]
+    RateLimit(RateLimit),
+}
+
+/// Recoverable rate limit error.
+#[derive(Display, Debug, Clone, PartialEq)]
+pub enum RateLimit {
+    /// Retry-After: <http-date>
+    #[display(fmt = "retry after date {}", _0)]
+    Date(String),
+    /// Retry-After: <delay-seconds>
+    #[display(fmt = "retry after number of seconds {}", _0)]
+    Seconds(u64),
 }
 
 /// Errors which can occur when attempting to generate resource uri.