Networking

NURL reaches the network through a pure-POSIX socket layer in the C runtime. No external framework exists at that layer. Every primitive is dual-stack IPv4/IPv6. Each integrates with the fiber reactor for async I/O.

TCP, UDP, and DNS

stdlib/std/net.nu, stdlib/std/udp.nu, and stdlib/std/dns.nu hold these.

HTTP

stdlib/ext/http_server.nu and its neighbors (http_router.nu, http_middleware.nu, http_static.nu, http_multipart.nu) build a routing HTTP/1.1 server on top of the TCP layer. server_run_pool drives it on a thread pool. server_run_async drives the same handlers on fibers with no code changes. Routing, middleware, and the request parser are ordinary functions either way.

stdlib/ext/http.nu / http_cli.nu are the HTTP client side, and http2_client.nu / http2_server.nu / http2_frame.nu / http2_hpack.nu implement HTTP/2.

TLS

You can use TLS in two ways:

• libssl-backed, via tcp_listen_tls / tcp_connect_tls — the HTTP server stack picks this up transparently by swapping tcp_listen for tcp_listen_tls. Covers SNI (multi-tenant certs on one listener), ALPN (needed for HTTP/2), mutual TLS, and live certificate reload for Let's-Encrypt-style rotation.
• Pure-NURL TLS 1.3, in stdlib/std/tls.nu / tls_server.nu — a from-scratch handshake, record layer, and certificate verification with no OpenSSL and no FFI beyond the plain TCP socket. It negotiates ChaCha20-Poly1305 or AES-128-GCM over X25519 or P-256. It verifies against the system trust store by default. tls_attach upgrades an already-connected socket, for STARTTLS-style protocols.

A program that never calls the _tls functions, or only uses the pure-NURL client, links libc only.

MQTT

stdlib/ext/mqtt.nu is a full MQTT 5.0 client over the TCP/TLS layer, with no dependency beyond the runtime's libssl:

$ `stdlib/ext/mqtt.nu`

@ main → i {
    : !MqttClient MqttErr r ( mqtt_connect
        `broker.example.com` 8883 `client-id` `user` `pass` )
    ?? r {
        T cl → {
            ( mqtt_subscribe cl `sensors/#` )
            ( mqtt_publish1 cl `sensors/temp` `21.4` )
            ( mqtt_disconnect cl )
            ^ 0
        }
        F e → { ( nurl_eprint ( mqtt_err_name e ) ) ^ 1 }
    }
}

It covers QoS 0/1/2 publishing with the full acknowledgment handshake, multi-topic subscribe, TLS by default (tls_verify on), and typed errors that separate transport faults from broker rejections. NURL does not yet support pipelined (multiple-in-flight) publishing. One packet is in flight at a time.

Next

• Cryptography — the primitives TLS and MQTT sit on.
• Concurrency — how these calls behave inside a fiber.
• For the exhaustive endpoint and flag list, see docs/NETWORKING.md.