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/*
* libwebsockets - small server side websockets and web server implementation
*
* Copyright (C) 2010-2018 Andy Green <andy@warmcat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation:
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*
* included from libwebsockets.h
*/
/*! \defgroup extensions Extension related functions
* ##Extension releated functions
*
* Ws defines optional extensions, lws provides the ability to implement these
* in user code if so desired.
*
* We provide one extensions permessage-deflate.
*/
///@{
/*
* NOTE: These public enums are part of the abi. If you want to add one,
* add it at where specified so existing users are unaffected.
*/
enum lws_extension_callback_reasons {
LWS_EXT_CB_CONSTRUCT = 4,
LWS_EXT_CB_CLIENT_CONSTRUCT = 5,
LWS_EXT_CB_DESTROY = 8,
LWS_EXT_CB_PACKET_TX_PRESEND = 12,
LWS_EXT_CB_PAYLOAD_TX = 21,
LWS_EXT_CB_PAYLOAD_RX = 22,
LWS_EXT_CB_OPTION_DEFAULT = 23,
LWS_EXT_CB_OPTION_SET = 24,
LWS_EXT_CB_OPTION_CONFIRM = 25,
LWS_EXT_CB_NAMED_OPTION_SET = 26,
/****** add new things just above ---^ ******/
};
/** enum lws_ext_options_types */
enum lws_ext_options_types {
EXTARG_NONE, /**< does not take an argument */
EXTARG_DEC, /**< requires a decimal argument */
EXTARG_OPT_DEC /**< may have an optional decimal argument */
/* Add new things just above here ---^
* This is part of the ABI, don't needlessly break compatibility */
};
/** struct lws_ext_options - Option arguments to the extension. These are
* used in the negotiation at ws upgrade time.
* The helper function lws_ext_parse_options()
* uses these to generate callbacks */
struct lws_ext_options {
const char *name; /**< Option name, eg, "server_no_context_takeover" */
enum lws_ext_options_types type; /**< What kind of args the option can take */
/* Add new things just above here ---^
* This is part of the ABI, don't needlessly break compatibility */
};
/** struct lws_ext_option_arg */
struct lws_ext_option_arg {
const char *option_name; /**< may be NULL, option_index used then */
int option_index; /**< argument ordinal to use if option_name missing */
const char *start; /**< value */
int len; /**< length of value */
};
/**
* typedef lws_extension_callback_function() - Hooks to allow extensions to operate
* \param context: Websockets context
* \param ext: This extension
* \param wsi: Opaque websocket instance pointer
* \param reason: The reason for the call
* \param user: Pointer to ptr to per-session user data allocated by library
* \param in: Pointer used for some callback reasons
* \param len: Length set for some callback reasons
*
* Each extension that is active on a particular connection receives
* callbacks during the connection lifetime to allow the extension to
* operate on websocket data and manage itself.
*
* Libwebsockets takes care of allocating and freeing "user" memory for
* each active extension on each connection. That is what is pointed to
* by the user parameter.
*
* LWS_EXT_CB_CONSTRUCT: called when the server has decided to
* select this extension from the list provided by the client,
* just before the server will send back the handshake accepting
* the connection with this extension active. This gives the
* extension a chance to initialize its connection context found
* in user.
*
* LWS_EXT_CB_CLIENT_CONSTRUCT: same as LWS_EXT_CB_CONSTRUCT
* but called when client is instantiating this extension. Some
* extensions will work the same on client and server side and then
* you can just merge handlers for both CONSTRUCTS.
*
* LWS_EXT_CB_DESTROY: called when the connection the extension was
* being used on is about to be closed and deallocated. It's the
* last chance for the extension to deallocate anything it has
* allocated in the user data (pointed to by user) before the
* user data is deleted. This same callback is used whether you
* are in client or server instantiation context.
*
* LWS_EXT_CB_PACKET_TX_PRESEND: this works the same way as
* LWS_EXT_CB_PACKET_RX_PREPARSE above, except it gives the
* extension a chance to change websocket data just before it will
* be sent out. Using the same lws_token pointer scheme in in,
* the extension can change the buffer and the length to be
* transmitted how it likes. Again if it wants to grow the
* buffer safely, it should copy the data into its own buffer and
* set the lws_tokens token pointer to it.
*
* LWS_EXT_CB_ARGS_VALIDATE:
*/
typedef int
lws_extension_callback_function(struct lws_context *context,
const struct lws_extension *ext, struct lws *wsi,
enum lws_extension_callback_reasons reason,
void *user, void *in, size_t len);
/** struct lws_extension - An extension we support */
struct lws_extension {
const char *name; /**< Formal extension name, eg, "permessage-deflate" */
lws_extension_callback_function *callback; /**< Service callback */
const char *client_offer; /**< String containing exts and options client offers */
/* Add new things just above here ---^
* This is part of the ABI, don't needlessly break compatibility */
};
/**
* lws_set_extension_option(): set extension option if possible
*
* \param wsi: websocket connection
* \param ext_name: name of ext, like "permessage-deflate"
* \param opt_name: name of option, like "rx_buf_size"
* \param opt_val: value to set option to
*/
LWS_VISIBLE LWS_EXTERN int
lws_set_extension_option(struct lws *wsi, const char *ext_name,
const char *opt_name, const char *opt_val);
/**
* lws_ext_parse_options() - deal with parsing negotiated extension options
*
* \param ext: related extension struct
* \param wsi: websocket connection
* \param ext_user: per-connection extension private data
* \param opts: list of supported options
* \param o: option string to parse
* \param len: length
*/
LWS_VISIBLE LWS_EXTERN int LWS_WARN_UNUSED_RESULT
lws_ext_parse_options(const struct lws_extension *ext, struct lws *wsi,
void *ext_user, const struct lws_ext_options *opts,
const char *o, int len);
/** lws_extension_callback_pm_deflate() - extension for RFC7692
*
* \param context: lws context
* \param ext: related lws_extension struct
* \param wsi: websocket connection
* \param reason: incoming callback reason
* \param user: per-connection extension private data
* \param in: pointer parameter
* \param len: length parameter
*
* Built-in callback implementing RFC7692 permessage-deflate
*/
LWS_EXTERN int
lws_extension_callback_pm_deflate(struct lws_context *context,
const struct lws_extension *ext,
struct lws *wsi,
enum lws_extension_callback_reasons reason,
void *user, void *in, size_t len);
/*
* The internal exts are part of the public abi
* If we add more extensions, publish the callback here ------v
*/
///@}
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