lws-protocols-plugins.h

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/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010 - 2019 Andy Green <andy@warmcat.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */
 
/*! \defgroup Protocols-and-Plugins Protocols and Plugins
 * \ingroup lwsapi
 *
 * ##Protocol and protocol plugin -related apis
 *
 * Protocols bind ws protocol names to a custom callback specific to that
 * protocol implementaion.
 *
 * A list of protocols can be passed in at context creation time, but it is
 * also legal to leave that NULL and add the protocols and their callback code
 * using plugins.
 *
 * Plugins are much preferable compared to cut and pasting code into an
 * application each time, since they can be used standalone.
 */
///@{
/** struct lws_protocols -      List of protocols and handlers client or server
 *                                      supports. */
 
struct lws_protocols {
        const char *name;
        /**< Protocol name that must match the one given in the client
         * Javascript new WebSocket(url, 'protocol') name. */
        lws_callback_function *callback;
        /**< The service callback used for this protocol.  It allows the
         * service action for an entire protocol to be encapsulated in
         * the protocol-specific callback */
        size_t per_session_data_size;
        /**< Each new connection using this protocol gets
         * this much memory allocated on connection establishment and
         * freed on connection takedown.  A pointer to this per-connection
         * allocation is passed into the callback in the 'user' parameter */
        size_t rx_buffer_size;
        /**< lws allocates this much space for rx data and informs callback
         * when something came.  Due to rx flow control, the callback may not
         * be able to consume it all without having to return to the event
         * loop.  That is supported in lws.
         *
         * If .tx_packet_size is 0, this also controls how much may be sent at
         * once for backwards compatibility.
         */
        unsigned int id;
        /**< ignored by lws, but useful to contain user information bound
         * to the selected protocol.  For example if this protocol was
         * called "myprotocol-v2", you might set id to 2, and the user
         * code that acts differently according to the version can do so by
         * switch (wsi->a.protocol->id), user code might use some bits as
         * capability flags based on selected protocol version, etc. */
        void *user; /**< ignored by lws, but user code can pass a pointer
                        here it can later access from the protocol callback */
        size_t tx_packet_size;
        /**< 0 indicates restrict send() size to .rx_buffer_size for backwards-
         * compatibility.
         * If greater than zero, a single send() is restricted to this amount
         * and any remainder is buffered by lws and sent afterwards also in
         * these size chunks.  Since that is expensive, it's preferable
         * to restrict one fragment you are trying to send to match this
         * size.
         */
 
        /* Add new things just above here ---^
         * This is part of the ABI, don't needlessly break compatibility */
};
 
#define LWS_PROTOCOL_LIST_TERM { NULL, NULL, 0, 0, 0, NULL, 0 }
 
/**
 * lws_vhost_name_to_protocol() - get vhost's protocol object from its name
 *
 * \param vh: vhost to search
 * \param name: protocol name
 *
 * Returns NULL or a pointer to the vhost's protocol of the requested name
 */
LWS_VISIBLE LWS_EXTERN const struct lws_protocols *
lws_vhost_name_to_protocol(struct lws_vhost *vh, const char *name);
 
/**
 * lws_get_protocol() - Returns a protocol pointer from a websocket
 *                                connection.
 * \param wsi:  pointer to struct websocket you want to know the protocol of
 *
 *
 *      Some apis can act on all live connections of a given protocol,
 *      this is how you can get a pointer to the active protocol if needed.
 */
LWS_VISIBLE LWS_EXTERN const struct lws_protocols *
lws_get_protocol(struct lws *wsi);
 
/** lws_protocol_get() -  deprecated: use lws_get_protocol */
LWS_VISIBLE LWS_EXTERN const struct lws_protocols *
lws_protocol_get(struct lws *wsi) LWS_WARN_DEPRECATED;
 
/**
 * lws_protocol_vh_priv_zalloc() - Allocate and zero down a protocol's per-vhost
 *                                 storage
 * \param vhost:        vhost the instance is related to
 * \param prot:         protocol the instance is related to
 * \param size:         bytes to allocate
 *
 * Protocols often find it useful to allocate a per-vhost struct, this is a
 * helper to be called in the per-vhost init LWS_CALLBACK_PROTOCOL_INIT
 */
LWS_VISIBLE LWS_EXTERN void *
lws_protocol_vh_priv_zalloc(struct lws_vhost *vhost,
                            const struct lws_protocols *prot, int size);
 
/**
 * lws_protocol_vh_priv_get() - retreive a protocol's per-vhost storage
 *
 * \param vhost:        vhost the instance is related to
 * \param prot:         protocol the instance is related to
 *
 * Recover a pointer to the allocated per-vhost storage for the protocol created
 * by lws_protocol_vh_priv_zalloc() earlier
 */
LWS_VISIBLE LWS_EXTERN void *
lws_protocol_vh_priv_get(struct lws_vhost *vhost,
                         const struct lws_protocols *prot);
 
/**
 * lws_vhd_find_by_pvo() - find a partner vhd
 *
 *  \param cx: the lws_context
 *  \param protname: the name of the lws_protocol the vhd belongs to
 *  \param pvo_name: the name of a pvo that must exist bound to the vhd
 *  \param pvo_value: the required value of the named pvo
 *
 * This allows architectures with multiple protocols bound together to
 * cleanly discover partner protocol instances even on completely
 * different vhosts.  For example, a proxy may consist of two protocols
 * listening on different vhosts, and there may be multiple instances
 * of the proxy in the same process.  It's desirable that each side of
 * the proxy is an independent protocol that can be freely bound to any
 * vhost, eg, allowing Unix Domain to tls / h2 proxying, or each side
 * bound to different network interfaces for localhost-only visibility
 * on one side, using existing vhost management.
 *
 * That leaves the problem that the two sides have to find each other
 * and bind at runtime.  This api allows each side to specify the
 * protocol name, and a common pvo name and pvo value that indicates
 * the two sides belong together, and search through all the instantiated
 * vhost-protocols looking for a match.  If found, the private allocation
 * (aka "vhd" of the match is returned).  NULL is returned on no match.
 *
 * Since this can only succeed when called by the last of the two
 * protocols to be instantiated, both sides should call it and handle
 * NULL gracefully, since it may mean that they were first and their
 * partner vhsot-protocol has not been instantiated yet.
 */
LWS_VISIBLE LWS_EXTERN void *
lws_vhd_find_by_pvo(struct lws_context *cx, const char *protname,
                    const char *pvo_name, const char *pvo_value);
 
 
/**
 * lws_adjust_protocol_psds - change a vhost protocol's per session data size
 *
 * \param wsi: a connection with the protocol to change
 * \param new_size: the new size of the per session data size for the protocol
 *
 * Returns user_space for the wsi, after allocating
 *
 * This should not be used except to initalize a vhost protocol's per session
 * data size one time, before any connections are accepted.
 *
 * Sometimes the protocol wraps another protocol and needs to discover and set
 * its per session data size at runtime.
 */
LWS_VISIBLE LWS_EXTERN void *
lws_adjust_protocol_psds(struct lws *wsi, size_t new_size);
 
/**
 * lws_finalize_startup() - drop initial process privileges
 *
 * \param context:      lws context
 *
 * This is called after the end of the vhost protocol initializations, but
 * you may choose to call it earlier
 */
LWS_VISIBLE LWS_EXTERN int
lws_finalize_startup(struct lws_context *context);
 
/**
 * lws_pvo_search() - helper to find a named pvo in a linked-list
 *
 * \param pvo:  the first pvo in the linked-list
 * \param name: the name of the pvo to return if found
 *
 * Returns NULL, or a pointer to the name pvo in the linked-list
 */
LWS_VISIBLE LWS_EXTERN const struct lws_protocol_vhost_options *
lws_pvo_search(const struct lws_protocol_vhost_options *pvo, const char *name);
 
/**
 * lws_pvo_get_str() - retreive a string pvo value
 *
 * \param in:   the first pvo in the linked-list
 * \param name: the name of the pvo to return if found
 * \param result: pointer to a const char * to get the result if any
 *
 * Returns 0 if found and *result set, or nonzero if not found
 */
LWS_VISIBLE LWS_EXTERN int
lws_pvo_get_str(void *in, const char *name, const char **result);
 
LWS_VISIBLE LWS_EXTERN int
lws_protocol_init(struct lws_context *context);
 
#define LWS_PLUGIN_API_MAGIC 191
 
/*
 * Abstract plugin header for any kind of plugin class, always at top of
 * actual class plugin export type.
 *
 * The export type object must be exported with the same name as the plugin
 * file, eg, libmyplugin.so must export a const one of these as the symbol
 * "myplugin".
 *
 * That is the only expected export from the plugin.
 */
 
typedef struct lws_plugin_header {
        const char *name;
        const char *_class;
        const char *lws_build_hash; /* set to LWS_BUILD_HASH */
 
        unsigned int api_magic;
        /* set to LWS_PLUGIN_API_MAGIC at plugin build time */
 
        /* plugin-class specific superclass data follows */
} lws_plugin_header_t;
 
/*
 * "lws_protocol_plugin" class export, for lws_protocol implementations done
 * as plugins
 */
typedef struct lws_plugin_protocol {
        lws_plugin_header_t hdr;
 
        const struct lws_protocols *protocols; /**< array of supported protocols provided by plugin */
        const struct lws_extension *extensions; /**< array of extensions provided by plugin */
        int count_protocols; /**< how many protocols */
        int count_extensions; /**< how many extensions */
} lws_plugin_protocol_t;
 
 
/*
 * This is the dynamic, runtime created part of the plugin instantiation.
 * These are kept in a linked-list and destroyed with the context.
 */
 
struct lws_plugin {
        struct lws_plugin *list; /**< linked list */
 
        const lws_plugin_header_t *hdr;
 
        union {
#if defined(LWS_WITH_LIBUV) && defined(UV_ERRNO_MAP)
#if (UV_VERSION_MAJOR > 0)
                uv_lib_t lib; /**< shared library pointer */
#endif
#endif
                void *l; /**<  */
        } u;
};
 
/*
 * Event lib library plugin type (when LWS_WITH_EVLIB_PLUGINS)
 * Public so new event libs can equally be supported outside lws itself
 */
 
typedef struct lws_plugin_evlib {
        lws_plugin_header_t hdr;
        const struct lws_event_loop_ops *ops;
} lws_plugin_evlib_t;
 
typedef int (*each_plugin_cb_t)(struct lws_plugin *p, void *user);
 
/**
 * lws_plugins_init() - dynamically load plugins of matching class from dirs
 *
 * \param pplugin:      pointer to linked-list for this kind of plugin
 * \param d: array of directory paths to look in
 * \param _class: class string that plugin must declare
 * \param filter: NULL, or a string that must appear after the third char of the plugin filename
 * \param each: NULL, or each_plugin_cb_t callback for each instantiated plugin
 * \param each_user: pointer passed to each callback
 *
 * Allows you to instantiate a class of plugins to a specified linked-list.
 * The each callback allows you to init each inistantiated callback and pass a
 * pointer each_user to it.
 *
 * To take down the plugins, pass a pointer to the linked-list head to
 * lws_plugins_destroy.
 *
 * This is used for lws protocol plugins but you can define your own plugin
 * class name like "mypluginclass", declare it in your plugin headers, and load
 * your own plugins to your own list using this api the same way.
 */
LWS_VISIBLE LWS_EXTERN int
lws_plugins_init(struct lws_plugin **pplugin, const char * const *d,
                 const char *_class, const char *filter,
                 each_plugin_cb_t each, void *each_user);
 
/**
 * lws_plugins_destroy() - dynamically unload list of plugins
 *
 * \param pplugin:      pointer to linked-list for this kind of plugin
 * \param each: NULL, or each_plugin_cb_t callback for each instantiated plugin
 * \param each_user: pointer passed to each callback
 *
 * Allows you to destroy a class of plugins from a specified linked-list
 * created by a call to lws_plugins_init().
 *
 * The each callback allows you to deinit each inistantiated callback and pass a
 * pointer each_user to it, just before its footprint is destroyed.
 */
LWS_VISIBLE LWS_EXTERN int
lws_plugins_destroy(struct lws_plugin **pplugin, each_plugin_cb_t each,
                    void *each_user);
 
#if defined(LWS_WITH_PLUGINS_BUILTIN)
 
/* provide exports for builtin plugin protocols */
 
extern const struct lws_protocols post_demo_protocols[1];
extern const struct lws_protocols lws_raw_proxy_protocols[1];
extern const struct lws_protocols lws_status_protocols[1];
extern const struct lws_protocols lws_mirror_protocols[1];
extern const struct lws_protocols lws_ssh_base_protocols[2];
extern const struct lws_protocols post_demo_protocols[1];
extern const struct lws_protocols dumb_increment_protocols[1];
extern const struct lws_protocols deaddrop_protocols[1];
extern const struct lws_protocols lws_raw_test_protocols[1];
extern const struct lws_protocols lws_sshd_demo_protocols[1];
extern const struct lws_protocols lws_acme_client_protocols[1];
extern const struct lws_protocols client_loopback_test_protocols[1];
extern const struct lws_protocols fulltext_demo_protocols[1];
extern const struct lws_protocols lws_openmetrics_export_protocols[
#if defined(LWS_WITH_SERVER) && defined(LWS_WITH_CLIENT) && defined(LWS_ROLE_WS)
        4
#else
#if defined(LWS_WITH_SERVER)
        3
#else
        1
#endif
#endif
        ];
 
#define LWSOMPROIDX_DIRECT_HTTP_SERVER          0
#define LWSOMPROIDX_PROX_HTTP_SERVER            1
#define LWSOMPROIDX_PROX_WS_SERVER              2
#define LWSOMPROIDX_PROX_WS_CLIENT              3
 
#endif
 
///@}