Struct HttpPushSender 

pub struct HttpPushSender { /* private fields */ }

HTTP-based PushSender using hyper.

Retries failed deliveries according to a configurable PushRetryPolicy.

Transport

With the tls-rustls feature (enabled by default via the a2a-protocol-sdk crate) this sender delivers over both http:// and https:// — the latter being the norm for production and what the A2A spec’s webhook field describes. Without the feature it is plaintext-HTTP only and fails fast on an https:// target with a clear, actionable error rather than a late, opaque connector failure.

You can always supply a fully custom TLS stack via RequestHandlerBuilder::with_push_sender; PushSender is a public, object-safe trait.

HTTPS and DNS-rebinding

The SSRF pre-flight (validate_webhook_url_with_dns) always runs, rejecting webhooks that resolve to private/loopback/link-local addresses. For http:// targets the validated IP is additionally pinned (the request dials the literal IP with the original Host header) to close the DNS-rebinding TOCTOU window. For https:// targets the IP is not pinned — the connection must present the original hostname for SNI and certificate verification — and the rebinding window is instead closed by TLS itself: an attacker who flips DNS to a private address after validation cannot present a certificate valid for the original hostname, so the handshake fails.

Security

• Rejects webhook URLs targeting private/loopback/link-local addresses to prevent SSRF attacks (including IPv4-in-IPv6 smuggling), and pins the validated IP against DNS-rebinding between validation and connect.
• Validates authentication credentials to prevent HTTP header injection (rejects values containing CR/LF characters).

Implementations

impl HttpPushSender

pub fn new() -> HttpPushSender

Creates a new HttpPushSender with the default 30-second request timeout and default retry policy.

pub fn with_timeout(request_timeout: Duration) -> HttpPushSender

Creates a new HttpPushSender with a custom per-request timeout.

pub fn with_tls_config(tls_config: ClientConfig) -> HttpPushSender

Creates an HttpPushSender that delivers HTTPS using a custom rustls ClientConfig instead of the default Mozilla root store.

Use this to trust an internal/private CA for webhook endpoints, or to present a client certificate for mutual TLS. Uses the default per-request timeout and retry policy (chain with_retry_policy to change them). http:// targets are still delivered in plaintext.

Requires the tls-rustls feature.

pub fn with_retry_policy(self, policy: PushRetryPolicy) -> HttpPushSender

Sets a custom retry policy for push notification delivery.

pub const fn allow_private_urls(self) -> HttpPushSender

Creates an HttpPushSender that allows private/loopback URLs.

Warning: This disables SSRF protection and should only be used in testing or trusted environments.

Trait Implementations

impl Debug for HttpPushSender

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for HttpPushSender

fn default() -> HttpPushSender

Returns the “default value” for a type.

impl PushSender for HttpPushSender

fn allows_private_urls(&self) -> bool

Returns true if this sender allows webhook URLs targeting private/loopback addresses. Used by the handler to skip SSRF validation at push config creation time in testing environments.

fn send<'a>( &'a self, url: &'a str, event: &'a StreamResponse, config: &'a TaskPushNotificationConfig, ) -> Pin<Box<dyn Future<Output = Result<(), A2aError>> + Send + 'a>>

Sends a streaming event to the client’s webhook URL.