The Origin header on a WebSocket handshake is set by browsers and can be set to anything by every other client. So an allow-list protects a cookie-authenticated browser session from other sites, and it proves nothing about who is connecting. A runnable server, a real headless-browser attack, and the handshake rule that follows.
A request deadline fired on a connection that carries many requests at once. Do you close the connection, or only the request? In a small Node lab, closing the HTTP/2 session failed two innocent requests, while cancelling only the stream let them finish on the same TCP connection. The same lab shows the one case where cancelling is not enough: a lost packet stalls every stream on a TCP connection, and a connection-level PING is the right way to tell.
How a client catches up after a reconnect without losing state, without duplicates, and without re-reading history. Built in steps (versions 0 to 4), from “read everything again” to a bounded log with a snapshot fallback, with what a real browser’s EventSource does on reconnect and on a non-200 response, a snapshot-ordering bug, and a decision tree.
When a request times out, the client cannot tell whether the request or only its acknowledgement was lost. This is why exactly-once delivery cannot be built, and why effectively-once processing is at-least-once delivery plus a receiver that deduplicates. A runnable experiment with a flaky network, the bug that still duplicates 89 of 200 requests, an atomic dedupe store, and a jitter simulation.
The Origin header on a WebSocket handshake is set by browsers and can be set to anything by every other client. So an allow-list protects a cookie-authenticated browser session from other sites, and it proves nothing about who is connecting. A runnable server, a real headless-browser attack, and the handshake rule that follows.
A request deadline fired on a connection that carries many requests at once. Do you close the connection, or only the request? In a small Node lab, closing the HTTP/2 session failed two innocent requests, while cancelling only the stream let them finish on the same TCP connection. The same lab shows the one case where cancelling is not enough: a lost packet stalls every stream on a TCP connection, and a connection-level PING is the right way to tell.
How a client catches up after a reconnect without losing state, without duplicates, and without re-reading history. Built in steps (versions 0 to 4), from “read everything again” to a bounded log with a snapshot fallback, with what a real browser’s EventSource does on reconnect and on a non-200 response, a snapshot-ordering bug, and a decision tree.
When a request times out, the client cannot tell whether the request or only its acknowledgement was lost. This is why exactly-once delivery cannot be built, and why effectively-once processing is at-least-once delivery plus a receiver that deduplicates. A runnable experiment with a flaky network, the bug that still duplicates 89 of 200 requests, an atomic dedupe store, and a jitter simulation.