= nng_ws(7) // // Copyright 2020 Staysail Systems, Inc. // Copyright 2018 Capitar IT Group BV // // This document is supplied under the terms of the MIT License, a // copy of which should be located in the distribution where this // file was obtained (LICENSE.txt). A copy of the license may also be // found online at https://opensource.org/licenses/MIT. // == NAME nng_ws - WebSocket transport == SYNOPSIS [source,c] ---- #include int nng_ws_register(void); int nng_wss_register(void); ---- == DESCRIPTION (((WebSocket)))(((transport, _ws_ and _wss_))) The ((_ws_ transport)) provides communication support between peers across a TCP/IP network using https://tools.ietf.org/html/rfc6455[WebSockets]. Both IPv4 and IPv6 are supported when the underlying platform also supports it. The protocol details are documented in http://nanomsg.org/rfcs/sp-websocket-v1.html[WebSocket Mapping for Scalability Protocols]. === Registration Depending upon how the library was built, it may be necessary to register the transport by calling xref:nng_ws_register.3.adoc[`nng_ws_register()`]. If ((TLS)) support is enabled in the library, secure WebSockets (over TLS v1.2) can be used as well, but the secure transport may have to be registered using the xref:nng_wss_register.3.adoc[`nng_wss_register()`] function. === URI Format (((URI, `ws://`))) This transport uses URIs using the scheme `ws://`, followed by an IP address or hostname, optionally followed by a colon and an TCP port number, optionally followed by a path. (If no port number is specified then port 80 is assumed. If no path is specified then a path of `/` is assumed.) For example, the URI `ws://localhost/app/pubsub` would use port 80 on localhost, with the path `/app/pubsub`. Secure WebSockets (((WebSockets, Secure)))(((URI, `wss://`))) (if enabled) use the scheme `wss://`, and the default TCP port number of 443. Otherwise the format is the same as for regular WebSockets. A URI may be restricted to IPv6 using the scheme `ws6://` or `wss6://`, and may be restricted to IPv4 using the scheme `ws4://` or `wss4://`. NOTE: Specifying `ws6://` or `wss6://` may not prevent IPv4 hosts from being used with IPv4-in-IPv6 addresses, particularly when using a wildcard hostname with listeners. The details of this varies across operating systems. NOTE: The `ws4://` , `ws6://`, `wss4://` and `wss6://` schemes are specific to _NNG_, and might not be understood by other implementations. TIP: We recommend using either numeric IP addresses, or names that are specific to either IPv4 or IPv6 to prevent confusion and surprises. When specifying IPv6 addresses, the address must be enclosed in square brackets (`[]`) to avoid confusion with the final colon separating the port. For example, the same path and port on the IPv6 loopback address (`::1`) would be specified as `ws://[::1]/app/pubsub`. NOTE: The value specified as the host, if any, will also be used in the `Host:` ((HTTP header)) during HTTP negotiation. To listen to all ports on the system, the host name may be elided from the URL on the listener. This will wind up listening to all interfaces on the system, with possible caveats for IPv4 and IPv6 depending on what the underlying system supports. (On most modern systems it will map to the special IPv6 address `::`, and both IPv4 and IPv6 connections will be permitted, with IPv4 addresses mapped to IPv6 addresses.) === Socket Address When using an xref:nng_sockaddr.5.adoc[`nng_sockaddr`] structure, the actual structure is either of type xref:nng_sockaddr_in.5.adoc[`nng_sockaddr_in`] (for IPv4) or xref:nng_sockaddr_in6.5.adoc[`nng_sockaddr_in6`] (for IPv6). === Server Instances This transport makes use of shared HTTP server (((HTTP, server))) instances, permitting multiple sockets or listeners to be configured with the same hostname and port. When creating a new listener, it is registered with an existing HTTP server instance if one can be found. Note that the matching algorithm is somewhat simple, using only a string based hostname or IP address and port to match. Therefore it is recommended to use only IP addresses or the empty string as the hostname in listener URLs. Likewise, when sharing a server instance, it may not be possible to alter TLS configuration if the server is already running, as there is only a single TLS configuration context for the entire server instance. All sharing of server instances is only typically possible within the same process. The server may also be used by other things (for example to serve static content), in the same process. === Transport Options The following transport options are available. Note that setting these must be done before the transport is started. NOTE: The TLS specific options (beginning with `NNG_OPT_TLS_`) are only available for `wss://` endpoints. ((`NNG_OPT_WS_REQUEST_HEADERS`)):: (string) Concatenation of multiple lines terminated by CRLF sequences, that can be used to add further headers to the HTTP request sent when connecting. This option can be set on dialers, and retrieved from pipes. ((`NNG_OPT_WS_RESPONSE_HEADERS`)):: (string) Concatenation of multiple lines terminated by CRLF sequences, that can be used to add further headers to the HTTP response sent when connecting. This option can be set on listeners, and retrieved from pipes. ((`NNG_OPT_WS_RECV_TEXT`)):: (bool) Enable receiving of TEXT frames at the WebSocket layer. This option should only be used with the low level xref:nng_stream.5.adoc[`nng_stream`] API. When set, the stream will accept in-bound TEXT frames as well as BINARY frames. NOTE: The SP protocols (such as xref:nng_req.7.adoc[REQ]) require BINARY frames as they pass binary protocol data. Hence this option should not be used with such protocols. NOTE: RFC 6455 requires that TEXT frames be discarded and the connection closed if the frame does not contain valid UTF-8 data. NNG does not perform any such validation. Applications that need to be strictly conformant should check for this themselves. ((`NNG_OPT_WS_SEND_TEXT`)):: (bool) Enable sending of TEXT frames at the WebSocket layer. This option should only be used with the low level xref:nng_stream.5.adoc[`nng_stream`] API. When set, the stream will send TEXT frames instead of BINARY frames. NOTE: NNG does not check the frame data, and will attempt to send whatever the client requests. Peers that are compliant with RFC 6455 will discard TEXT frames (and break the connection) if they do not contain valid UTF-8. ((`NNG_OPT_TLS_CONFIG`)):: (`nng_tls_config *`) The underlying TLS configuration object for `wss://` endpoints. A hold is placed on the underlying configuration object before returning it. The caller should release the object with xref:nng_tls_config_free.3tls.adoc[`nng_tls_config_free()`] when it no longer needs the TLS configuration. TIP: Use this option when advanced TLS configuration is required. ((`NNG_OPT_TLS_CA_FILE`)):: (string) Write-only option naming a file containing certificates to use for peer validation. See xref:nng_tls_config_ca_file.3tls.adoc[`nng_tls_config_ca_file()`] for more information. ((`NNG_OPT_TLS_CERT_KEY_FILE`)):: (string) Write-only option naming a file containing the local certificate and associated private key. The private key used must be unencrypted. See xref:nng_tls_config_own_cert.3tls.adoc[`nng_tls_config_own_cert()`] for more information. ((`NNG_OPT_TLS_AUTH_MODE`)):: (`int`) Write-only option used to configure the authentication mode used. See xref:nng_tls_config_auth_mode.3tls.adoc[`nng_tls_config_auth_mode()`] for more details. `NNG_OPT_TLS_VERIFIED`:: (`bool`) Whether the remote peer has been properly verified using TLS authentication. May return incorrect results if peer authentication is disabled. // We should also look at a hook mechanism for listeners. Probably this could // look like NNG_OPT_WS_LISTEN_HOOK_FUNC which would take a function pointer // along the lines of int hook(void *, char *req_headers, char **res_headers), // and NNG_OPT_LISTEN_HOOK_ARG that passes the void * passed in as first arg. // Alternatively we can uplevel the HTTP API and pass the actual HTTP objects. == SEE ALSO [.text-left] xref:nng_tls_config_alloc.3tls.adoc[nng_tls_config_alloc(3tls)], xref:nng_sockaddr.5.adoc[nng_sockaddr(5)], xref:nng_sockaddr_in.5.adoc[nng_sockaddr_in(5)], xref:nng_sockaddr_in6.5.adoc[nng_sockaddr_in6(5)], xref:nng.7.adoc[nng(7)]